Sample records for abrasion wear resistance

  1. Wear resistance and mechanisms of composite hardfacings at abrasive impact erosion wear

    NASA Astrophysics Data System (ADS)

    Surzhenkov, A.; Viljus, M.; Simson, T.; Tarbe, R.; Saarna, M.; Casesnoves, F.

    2017-05-01

    Tungsten carbide based hardmetal containing sprayed and melted composite hardfacings are prospective for protection against abrasive wear. For selection of abrasive wear resistant hardfacings under intensive impact wear conditions, both mechanical properties (hardness, fracture toughness, etc.) and abrasive wear conditions (type of abrasive, impact velocity, etc.) should be considered. This study focuses on the wear (wear rate and mechanisms) of thick metal-matrix composite hardfacings with hardmetal (WC-Co) reinforcement produced by powder metallurgy technology. The influence of the hardmetal reinforcement type on the wear resistance at different abrasive impact erosion wear (AIEW) conditions was studied. An optimal reinforcement for various wear conditions is described. Based on wear mechanism studies, a mathematical model for wear prediction was drafted.

  2. Abrasive wear of ceramic wear protection at ambient and high temperatures

    NASA Astrophysics Data System (ADS)

    Varga, M.; Adam, K.; Tumma, M.; Alessio, K. O.

    2017-05-01

    Ceramic wear protection is often applied in abrasive conditions due to their excellent wear resistance. This is especially necessary in heavy industries conveying large amounts of raw materials, e.g. in steel industry. Some plants also require material transport at high temperatures and velocities, making the need of temperature stable and abrasion resistant wear protection necessary. Various types and wear behaviour of ceramic protection are known. Hence, the goal of this study is to identify the best suitable ceramic materials for abrasive conditions in harsh environments at temperatures up to 950°C and severe thermal gradients. Chamottes, known for their excellent thermal shock resistance are compared to high abrasion resistant ceramic wear tiles and a cost efficient cement-bounded hard compound. Testing was done under high-stress three-body abrasion regime with a modified ASTM G65 apparatus enabling for investigations up to ~950°C. Thereto heated abrasive is introduced into the wear track and also preheated ceramic samples were used and compared to ambient temperature experiments. Results indicate a significant temperature influence on chamottes and the hard compound. While the chamottes benefit from temperature increase, the cement-bounded hard compound showed its limitation at abrasive temperatures of 950°C. The high abrasion resistant wear tiles represented the materials with the best wear resistance and less temperature influence in the investigated range.

  3. Structural transformations, strengthening, and wear resistance of titanium nickelide upon abrasive and adhesive wear

    NASA Astrophysics Data System (ADS)

    Korshunov, L. G.; Pushin, V. G.; Chernenko, N. L.; Makarov, V. V.

    2010-07-01

    Wear resistance and structural transformations upon abrasive and adhesive wear of titanium nickelide Ti49.4Ni50.6 in microcrystalline (MC) and submicrocrystalline (SMC) states have been investigated. It has been shown that the abrasive wear resistance of this alloy exceeds that of the steel 12Kh18N9 by a factor of about 2, that of the steel 110G13 (Hadfield steel), by a factor of 1.3, and is close to that of the steel 95Kh18. Upon adhesive wear in a testing-temperature range from -50 to +300°C, the Ti49.4Ni50.6 alloy, as compared to the steel 12Kh18N9, is characterized by the wear rate that is tens of times smaller and by a reduced (1.5-2.0 times) friction coefficient. The enhanced wear resistance of the Ti49.4Ni50.6 alloy is due to the development of intense strain hardening in it and to a high fracture toughness, which is a consequence of effective relaxation of high contact stresses arising in the surface layer of the alloy. The SMC state produced in the alloy with the help of equal-channel angular pressing (ECAP) has no effect on the abrasive wear resistance of the alloy. The favorable effect of ECAP on the wear resistance of the Ti49.4Ni50.6 alloy takes place under conditions of its adhesive wear at temperatures from -25 to +70°C. The electron-microscopic investigation showed that under conditions of wear at negative and room temperatures in the surface layer (1-5 μm thick) of titanium nickelide there arises a mixed structure consisting of an amorphous phase and nanocrystals of supposedly austenite and martensite. Upon friction at 200-300°C, a nanocrystalline structure of the B2 phase arises near the alloy surface, which, as is the case with the amorphous-nanocrystalline structure, is characterized by significant effective strength and wear resistance.

  4. Abrasive Wear Resistance of Tool Steels Evaluated by the Pin-on-Disc Testing

    NASA Astrophysics Data System (ADS)

    Bressan, José Divo; Schopf, Roberto Alexandre

    2011-05-01

    Present work examines tool steels abrasion wear resistance and the abrasion mechanisms which are one main contributor to failure of tooling in metal forming industry. Tooling used in cutting and metal forming processes without lubrication fails due to this type of wear. In the workshop and engineering practice, it is common to relate wear resistance as function of material hardness only. However, there are others parameters which influences wear such as: fracture toughness, type of crystalline structure and the occurrence of hard precipitate in the metallic matrix and also its nature. In the present investigation, the wear mechanisms acting in tool steels were analyzed and, by normalized tests, wear resistance performance of nine different types of tool steels were evaluated by pin-on-disc testing. Conventional tool steels commonly used in tooling such as AISI H13 and AISI A2 were compared in relation to tool steels fabricated by sintering process such as Crucible CPM 3V, CPM 9V and M4 steels. Friction and wear testing were carried out in a pin-on-disc automated equipment which pin was tool steel and the counter-face was a abrasive disc of silicon carbide. Normal load of 5 N, sliding velocity of 0.45 m/s, total sliding distance of 3000 m and room temperature were employed. The wear rate was calculated by the Archard's equation and from the plotted graphs of pin cumulated volume loss versus sliding distance. Specimens were appropriately heat treated by quenching and three tempering cycles. Percentage of alloying elements, metallographic analyses of microstructure and Vickers microhardness of specimens were performed, analyzed and correlated with wear rate. The work is concluded by the presentation of a rank of tool steel wear rate, comparing the different tool steel abrasion wear resistance: the best tool steel wear resistance evaluated was the Crucible CPM 9V steel.

  5. Assessment of thermal spray coatings for wear and abrasion resistance applications

    NASA Astrophysics Data System (ADS)

    Karode, Ishaan Nitin

    Thermal spray cermet and metallic coatings are extensively used for wear, abrasion and corrosion control in a variety of industries. The first part of the thesis focuses mainly on testing of sand erosion resistance of thermal spray coatings on carbon composites used in the manufacture of helicopter rotor blades. The test set-up employed is a sand blasting machine and is an effort to duplicate the in-flight conditions especially those encountered in hot arid conditions. The technique adopted follows the Department of Defence test method standard. Carbon Composites have excellent stiffness, strength and low weight/density. The strength to weight ratio is high. Hence, these are used in aerospace applications to a large extent. However, the biggest problem encountered with carbon composites is its low abrasion resistance as its surface is very weak. Hence, thermal spray coatings are used to improve the surface properties of CFRP. Zinc bond coats and WC-Co coatings were tested. However, high amount of thermal stresses were developed between the substrate and the coating due to large differences in the CTE's of the both, leading to high mass losses within two minutes and just 130 grams of sand sprayed on to the coatings with the sand blasting machine built; and hence the coatings with CC as a substrate could not qualify for the application. The second part of the thesis focuses on the assessment of different thermal spray coatings used for manufacture of mechanical seals in pumps and analyze the best coating material for the wear resistance application through detail quantification of material loss by block-on-ring test set-up. A machine based on Block-on-ring test set-up following ASTM G77 (Measurement of Adhesive wear resistance of thermal spray coatings) standards was built to duplicate the pump conditions. Thermally sprayed coated materials were tested in different conditions (Load, time, abrasive). WC-Co had the highest wear resistance (lower volume losses) and

  6. Micro-Abrasion Wear Resistance of Borided 316L Stainless Steel and AISI 1018 Steel

    NASA Astrophysics Data System (ADS)

    Reséndiz-Calderon, C. D.; Rodríguez-Castro, G. A.; Meneses-Amador, A.; Campos-Silva, I. E.; Andraca-Adame, J.; Palomar-Pardavé, M. E.; Gallardo-Hernández, E. A.

    2017-11-01

    The 316L stainless steel has high corrosion resistance but low tribological performance. In different industrial sectors (biomedical, chemical, petrochemical, and nuclear engineering), improvement upon wear resistance of 316L stainless steel components using accessible and inexpensive methods is critical. The AISI 1018 steel is widely used in industry, but its tribological performance is not the best among steels. Therefore, in this study the behavior of the borided 316L stainless steel and 1018 steel is evaluated under micro-abrasion wear. The boriding was carried out at 1223 K over 6 h of exposure time, resulting in a biphase layer composed of FeB/Fe2B phases. In order to evaluate Fe2B phase with no influence from FeB phase, AISI 1018 steel samples were borided at 1273 K for over 20 min and then diffusion annealed at 1273 K over 2 h to obtain a Fe2B mono-phase layer. Micro-abrasion wear resistance was evaluated by a commercial micro-abrasion testing rig using a mix of F-1200 SiC particles with deionized water as abrasive slurry. The obtained wear rates for FeB and Fe2B phases and for the 316L stainless steel were compared. Wear resistance of 316L stainless steel increases after boriding. The wear mechanisms for both phases and for the stainless steel were identified. Also, transient conditions for rolling and grooving abrasion were determined for the FeB and Fe2B phases.

  7. Investigation of wear resistance of polyurethanes in abrasive soil mass

    NASA Astrophysics Data System (ADS)

    Napiórkowski, Jerzy; Ligier, Krzysztof

    2018-04-01

    This paper presents a comparative study of polyurethane wear in different abrasive soil masses. Two types of polyurethanes of various chemical compositions and untreated 38GSA steel were tested, the latter being used as a reference standard. The study was conducted in natural soil mass at a "rotating bowl" stand. Relative wear resistance was determined from measurements of mass wear for the materials under study. The condition of the surface of the materials under wear test was analysed.

  8. Interfacing superhydrophobic silica nanoparticle films with graphene and thermoplastic polyurethane for wear/abrasion resistance.

    PubMed

    Naderizadeh, Sara; Athanassiou, Athanassia; Bayer, Ilker S

    2018-06-01

    Nanoparticle films are one of the most suitable platforms for obtaining sub-micrometer and nanometer dual-scale surface texture required for liquid repellency. The assembly of superhydrophobic nanoparticles into conformal and strongly adherent films having abrasion-induced wear resistance still poses a significant challenge. Various techniques have been developed over the years to render nanoparticle films with good liquid repellent properties and transparency. However, forming abrasion resistant superhydrophobic nanoparticle films on hard surfaces is challenging. One possibility is to partially embed or weld nanoparticles in thin thermoplastic primers applied over metals. Hexamethyldisilazane-functionalized fumed silica nanoparticle films spray deposited on aluminum surfaces were rendered abrasion resistant by thermally welding them into thermoplastic polyurethane (TPU) primer applied a priori over aluminum. Different solvents, nanoparticle concentrations and annealing temperatures were studied to optimize nanoparticle film morphology and hydrophobicity. Thermal annealing at 150 °C enhanced stability and wear resistance of nanoparticle films. A thin thermal interface layer of graphene nanoplatelets (GnPs) between the primer and the nanoparticle film significantly improved superhydrophobic wear resistance after annealing. As such, superhydrophobic nanocomposite films with the GnPs thermal interface layer displayed superior abrasion-induced wear resistance under 20 kPa compared to films having no GnPs-based thermal interface. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. Behaviors of 40Cr steel treated by laser quenching on impact abrasive wear

    NASA Astrophysics Data System (ADS)

    Chen, Zhikai; Zhu, Qinghai; Wang, Jing; Yun, Xiao; He, Bing; Luo, Jingshuai

    2018-07-01

    In present work, laser quenching had been carried out to improve the impact abrasive wear resistance of 40Cr steel. The distinct microstructure between original and quenched region was demonstrated after laser quenching. Since the effect of temperature and cooling rate, the phase combinations were apparently different for quenched layer in depth. The impact abrasive wear resistance of sample was experimentally investigated and the improved level was assessed in light of the average mass loss of three repetitive tests. Worn surface was detected by means of SEM, OM and EDS, and results showed that three typical failure modes were performed during the processing of impact abrasive wear, including abrasive wear, impact effect and rolling contact fatigue. Basing on the different worn surface profile, the mainly failure mode was respectively pointed out for matrix and quenched sample, which was significantly in accordance with the result of impact abrasive wear.

  10. Effects of Load and Speed on Wear Rate of Abrasive Wear for 2014 Al Alloy

    NASA Astrophysics Data System (ADS)

    Odabas, D.

    2018-01-01

    In this paper, the effects of the normal load and sliding speed on wear rate of two-body abrasive wear for 2014 Al Alloy were investigated in detail. In order to understand the variation in wear behaviour with load and speed, wear tests were carried out at a sliding distance of 11 m, a speed of 0.36 m/s, a duration of 30 s and loads in the range 3-11 N using 220 grit abrasive paper, and at a speed range 0.09-0.90 m/s, a load of 5 N and an average sliding distance of 11 m using abrasive papers of 150 grit size under dry friction conditions. Before the wear tests, solution treatment of the 2014 Al alloy was carried out at temperatures of 505 and 520 °C for 1 h in a muffle furnace and then quenched in cold water at 15 °C. Later, the ageing treatment was carried out at 185 °C for 8 h in the furnace. Generally, wear rate due to time increased linearly and linear wear resistance decreased with increasing loads. However, the wear rate was directly proportional to the load up to a critical load of 7 N. After this load, the slope of the curves decreased because the excessive deformation of the worn surface and the instability of the abrasive grains began to increase. When the load on an abrasive grain reaches a critical value, the groove width is about 0.17 of the abrasive grain diameter, and the abrasive grains begin to fail. The wear rate due to time increased slightly as the sliding speed increased in the range 0.09-0.90 m/s. The reason for this is that changes arising from strain rate and friction heating are expected with increasing sliding speeds.

  11. A method for increase abrasive wear resistance parts by obtaining on methods casting on gasifying models

    NASA Astrophysics Data System (ADS)

    Sedukhin, V. V.; Anikeev, A. N.; Chumanov, I. V.

    2017-11-01

    Method optimizes hardening working layer parts’, working in high-abrasive conditions looks in this work: bland refractory particles WC and TiC in respect of 70/30 wt. % prepared by beforehand is applied on polystyrene model in casting’ mould. After metal poured in mould, withstand for crystallization, and then a study is carried out. Study macro- and microstructure received samples allows to say that thickness and structure received hardened layer depends on duration interactions blend harder carbides and liquid metal. Different character interactions various dispersed particles and matrix metal observed under the same conditions. Tests abrasive wear resistance received materials of method calculating residual masses was conducted in laboratory’ conditions. Results research wear resistance showed about that method obtaining harder coating of blend carbide tungsten and carbide titanium by means of drawing on surface foam polystyrene model before moulding, allows receive details with surface has wear resistance in 2.5 times higher, than details of analogy steel uncoated. Wherein energy costs necessary for transformation units mass’ substances in powder at obtained harder layer in 2.06 times higher, than materials uncoated.

  12. Abrasive wear of Hilong BoTN hardfacings

    NASA Astrophysics Data System (ADS)

    Fedorova, L.; Fedorov, S.; Sadovnikov, A.; Ivanova, Y.; Voronina, M.

    2018-02-01

    The spread of steels, which are used to produce locks of steel drill pipes, adversely affects their wear resistance, which, in combination with low hardness of HV 2400 ... 2800 MPa as well as of the thread of screw, results in low wear resistance and the need for their reconstruction at the pipe control shop. An efficient way of improving the quality of drill pipe jonts is to hard-face them by the outside diameter with wear-resistant materials (hardbanding). One of the companies engaged in the development of hardfacing materials and hardbanding is Hilong (China) with weld seams of the brand BoTn. According to the results of the studies the following conclusion can be made: hardfacing increases the durability of the hardware, contributing to an increase in wear resistance of locks of DP under the conditions of abrasive action of aggressive geological formations; the usage of DP without wear-resistant weld seams is impermissible, because their further operation, as part of the drill-stem, can lead to emergency consequences; application of the pipes with the hardfacing collars together with the collars without hardfacing, due to varying degree of wear of jonts in the drill-stem, is also impermissible.

  13. The effect of microstructure on abrasive wear of steel

    NASA Astrophysics Data System (ADS)

    Kešner, A.; Chotëborský, R.; Linda, M.

    2017-09-01

    Abrasive wear of agricultural tools is one of the biggest problems in currently being. The amount of abrasive wear, depending on the microstructure, has been investigated in this work. Steels 25CrMo4 and 51CrV4 were used in this work to determine the effect of the microstructure on the abrasive wear. These steels are commonly used for components that have to withstand abrasive wear.SEM analysis was used to detect the microstructure. The standardized ASTM G65 method was used to compare the abrasive wear of steels. The results show that the abrasive wear depends on the microstructure of steels.

  14. Abrasive wear behavior of heat-treated ABC-silicon carbide

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Xiao Feng; Lee, Gun Y.; Chen, Da

    2002-06-17

    Hot-pressed silicon carbide, containing aluminum, boron, and carbon additives (ABC-SiC), was subjected to three-body and two-body wear testing using diamond abrasives over a range of sizes. In general, the wear resistance of ABC-SiC, with suitable heat treatment, was superior to that of commercial SiC.

  15. Interaction between attrition,abrasion and erosion in tooth wear.

    PubMed

    Addy, M; Shellis, R P

    2006-01-01

    Tooth wear is the result of three processes: abrasion (wear produced by interaction between teeth and other materials), attrition (wear through tooth-tooth contact) and erosion (dissolution of hard tissue by acidic substances). A further process (abfraction) might potentiate wear by abrasion and/or erosion. Both clinical and experimental observations show that individual wear mechanisms rarely act alone but interact with each other. The most important interaction is the potentiation of abrasion by erosive damage to the dental hard tissues. This interaction seems to be the major factor in occlusal and cervical wear. The available evidence seems insufficient to establish whether abfraction is an important contributor to tooth wear in vivo. Saliva can modulate erosive/abrasive tooth wear through formation of pellicle and by remineralisation but cannot prevent it.

  16. Abrasive wear behavior of in-situ RZ5-10wt%TiC composite

    NASA Astrophysics Data System (ADS)

    Mehra, Deepak; Mahapatra, M. M.; Harsha, S. P.

    2018-05-01

    RZ5 Magnesium alloys containing zinc, rare earth and zirconium are well-known to have high specific strength, good creep resistance widely used in aerospace components. The incorporation of hard ceramic strengthens RZ5 mg alloy. The RZ5-10wt%TiC composite has been fabricated in situ using RZ5 mg alloy as matrix and TiC as reinforcement by self propagating high temperature synthesis (SHS) technique. This paper investigates the abrasive wear behavior of RZ5-10wt%TiC. Tests were performed using pin-on-disc apparatus against 600 grit abrasive paper by varying the sliding distance and applied load. The results showed improvement in the wear resistance of testing composite as compared to the unreinforced RZ5 Mg alloy. The coefficient of friction and weight loss increased linearly as applied load and sliding distance increased. The field emission scanning electron microscopic (FESEM) showed dominate wear mechanisms: abrasion, ploughing grooves.

  17. Study of Abrasive Wear Volume Map for PTFE and PTFE Composites

    NASA Astrophysics Data System (ADS)

    Unal, H.; Sen, U.; Mimaroglu, A.

    2007-11-01

    The potential of this work is based on consideration of wear volume map for the evaluation of abrasive wear performance of polytetrafluoroethylene (PTFE) and PTFE composites. The fillers used in the composite are 25% bronze, 35% graphite and 17% glass fibre glass (GFR). The influence of filler materials, abrasion surface roughness and applied load values on abrasive wear performance of PTFE and PTFE composites were studied and evaluated. Experimental abrasive wear tests were carried out at atmospheric condition on pin-on-disc wear tribometer. Tests were performed under 4, 6, 8 and 10 N load values, travelling speed of 1 m/sec and abrasion surface roughness values of 5, 20 and 45 µm. Wear volume maps were obtained and the results showed that the lowest wear volume rate for PTFE is reached using GFR filler. Furthermore, the results also showed that the higher is the applied load and the roughness of the abrasion surface, the higher is the wear rate. Finally it is also concluded that abrasive wear process mechanism include ploughing and cutting mechanisms.

  18. Effect of abrasive grit size on wear of manganese-zinc ferrite under three-body abrasion

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1987-01-01

    Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and deformed layers produced in single-crystal Mn-Zn ferrites under three-body abrasion. The abrasion mechanism of Mn-Zn ferrite changes drastically with the size of abrasive grits. With 15-micron (1000-mesh) SiC grits, abrasion of Mn-Zn ferrite is due principally to brittle fracture; while with 4- and 2-micron (4000- and 6000-mesh) SiC grits, abrasion is due to plastic deformation and fracture. Both microcracking and plastic flow produce polycrystalline states on the wear surfaces of single-crystal Mn-Zn ferrites. Coefficient of wear, total thickness of the deformed layers, and surface roughness of the wear surfaces increase markedly with an increase in abrasive grit size. The total thicknesses of the deformed layers are 3 microns for the ferrite abraded by 15-micron SiC, 0.9 microns for the ferrite abraded by 4-micron SiC, and 0.8 microns for the ferrite abraded by 1-micron SiC.

  19. The interactions between attrition, abrasion and erosion in tooth wear.

    PubMed

    Shellis, R Peter; Addy, Martin

    2014-01-01

    Tooth wear is the result of three processes: abrasion (wear produced by interaction between teeth and other materials), attrition (wear through tooth-tooth contact) and erosion (dissolution of hard tissue by acidic substances). A further process (abfraction) might potentiate wear by abrasion and/or erosion. Knowledge of these tooth wear processes and their interactions is reviewed. Both clinical and experimental observations show that individual wear mechanisms rarely act alone but interact with each other. The most important interaction is the potentiation of abrasion by erosive damage to the dental hard tissues. This interaction seems to be the major factor in occlusal and cervical wear. The available evidence is insufficient to establish whether abfraction is an important contributor to tooth wear in vivo. Saliva can modulate erosive/abrasive tooth wear, especially through formation of pellicle, but cannot prevent it. © 2014 S. Karger AG, Basel.

  20. Abrasive wear of resin composites as related to finishing and polishing procedures.

    PubMed

    Turssi, Cecilia P; Ferracane, Jack L; Serra, Mônica C

    2005-07-01

    Finishing and polishing procedures may cause topographical changes and introduce subsurface microcracks in dental composite restoratives. Since both of these effects may contribute toward the kinetics of wear, the purpose of this study was to assess and correlate the wear and surface roughness of minifilled and nanofilled composites finished and polished by different methods. Specimens (n=10) made of a minifilled and a nanofilled composite were finished and polished with one of the four sequences: (1) tungsten carbide burs plus Al(2)O(3)-impregnated brush (CbBr) or (2) tungsten carbide burs plus diamond-impregnated cup (CbCp), (3) diamond burs plus brush (DmBr) or (4) diamond burs plus cup (DmCp). As a control, abrasive papers were used. After surface roughness had been quantified, three-body abrasion was simulated using the OHSU wear machine. The wear facets were then scanned to measure wear depth and post-testing roughness. All sets of data were subjected to ANOVA and Tukey's tests (alpha=0.05). Pearson's correlation test was applied to check for the existence of a relationship between pre-testing roughness and wear. Significantly smoother surfaces were attained with the sequences CbBr and CbCp, whereas DmCp yielded the roughest surface. Regardless of the finishing/polishing technique, the nanofilled composite exhibited the lowest pre-testing roughness and wear. There was no correlation between the surface roughness achieved after finishing/polishing procedures and wear (p=0.3899). Nano-sized materials may have improved abrasive wear resistance over minifilled composites. The absence of correlation between wear and surface roughness produced by different finishing/polishing methods suggests that the latter negligibly influences material loss due to three-body abrasion.

  1. Experimental Rock-on-Rock Abrasive Wear Under Aqueous Conditions: its Role in Subglacial Abrasion

    NASA Astrophysics Data System (ADS)

    Rutter, E. H.; Lee, A. G.

    2003-12-01

    We have determined experimentally the rate of abrasive wear of rock on rock for a range of rock types as a function of normal stress and shear displacement. Unlike abrasive wear in fault zones, where wear products accumulate as a thickening gouge zone, in our experiments wear particles were removed by flowing water. The experiments are thus directly pertinent to one of the most important processes in subglacial erosion, and to some extent in river incision. Wear was produced between rotating discs machined from rock samples and measured from the progressive approach of the disc axes towards each other under various levels of normal load. Shear displacements of several km were produced. Optical and scanning electron microscopy were used to study the worn rock surfaces, and particle size distributions in wear products were characterized using a laser particle size analyzer. Rock types studied were sandstones of various porosities and cement characteristics, schists and a granite. In all cases abrasion rate decreased logarithmically with displacement by up to 2 orders of magnitude until a steady state was approached, but only after at least 1 km displacement. The more porous, less-well cemented rocks wore fastest. Amount of abrasion could be characterized quantitatively using an exponentially decaying plus a steady-state term. Wear rate increased non-linearly with normal contact stress, apparently to an asymptote defined by the unconfined compressive strength. Microstructural study showed that the well-cemented and/or lowest porosity rocks wore by progressive abrasion of grains without plucking, whereas whole grains were plucked out of weakly-cemented and/or more porous rocks. This difference in behavior was reflected in wear-product particle size distributions. Where whole-grain plucking was possible, wear products were dominated by particles of the original grain size rather than finer rock flour. Comparison of our results to glacier basal abrasive wear estimated

  2. Tribological properties of multifunctional coatings with Shape Memory Effect in abrasive wear

    NASA Astrophysics Data System (ADS)

    Blednova, Zh. M.; Dmitrenko, D. V.; Balaev, E. U. O.

    2018-01-01

    The article gives research results of the abrasive wear process on samples made of Steel 1045, U10 and with applied composite surface layer "Nickel-Multicomponent material with Shape Memory Effect (SME) based on TiNi". For the tests we have chosen TiNiZr, which is in the martensite state and TiNiHfCu, which is in the austenitic state at the test temperature. The formation of the surface layer was carried out by high-speed oxygen-fuel deposition in a protective atmosphere of argon. In the wear test, Al2O3 corundum powder was used as an abrasive. It is shown that the wear rate of samples with a composite surface layer of multicomponent materials with SME is significantly reduced in comparison with the base, which is explained by reversible phase transformations of the surface layer with SME. After carrying out the additional surface plastic deformation (SPD), the resistance of the laminated composition to abrasion wear has greatly enhanced, due to the reinforcing effect of the SPD. It is recommended for products working in conditions of abrasive wear and high temperatures to use the complex formation technology of the surface composition "steel-nickel-material with high-temperature SME", including preparation of the substrate surface and the deposited material, high-speed spraying in the protective atmosphere of argon, followed by SPD.

  3. Resistance to abrasion of extrinsic porcelain esthetic characterization techniques.

    PubMed

    Chi, Woo J; Browning, William; Looney, Stephen; Mackert, J Rodway; Windhorn, Richard J; Rueggeberg, Frederick

    2017-01-01

    A novel esthetic porcelain characterization technique involves mixing an appropriate amount of ceramic colorants with clear, low-fusing porcelain (LFP), applying the mixture on the external surfaces, and firing the combined components onto the surface of restorations in a porcelain oven. This method may provide better esthetic qualities and toothbrush abrasion resistance compared to the conventional techniques of applying color-corrective porcelain colorants alone, or applying a clear glaze layer over the colorants. However, there is no scientific literature to support this claim. This research evaluated toothbrush abrasion resistance of a novel porcelain esthetic characterization technique by subjecting specimens to various durations of simulated toothbrush abrasion. The results were compared to those obtained using the conventional characterization techniques of colorant application only or colorant followed by placement of a clear over-glaze. Four experimental groups, all of which were a leucite reinforced ceramic of E TC1 (Vita A1) shade, were prepared and fired in a porcelain oven according to the manufacturer's instructions. Group S (stain only) was characterized by application of surface colorants to provide a definitive shade of Vita A3.5. Group GS (glaze over stain) was characterized by application of a layer of glaze over the existing colorant layer as used for Group S. Group SL (stain+LFP) was characterized by application of a mixture of colorants and clear low-fusing add-on porcelain to provide a definitive shade of Vita A3.5. Group C (Control) was used as a control without any surface characterization. The 4 groups were subjected to mechanical toothbrushing using a 1:1 water-to-toothpaste solution for a simulated duration of 32 years of clinical use. The amount of wear was measured at time intervals simulating every 4 years of toothbrushing. These parameters were evaluated longitudinally for all groups as well as compared at similar time points among

  4. The microstructural dependence of wear resistance in austenite containing plate steels

    NASA Astrophysics Data System (ADS)

    Wolfram, Preston Charles

    The purpose of this project was to examine the microstructural dependence of wear resistance of various plate steels, with interests in exploring the influence of retained austenite (RA). Materials resistant to abrasive wear are desirable in the industrial areas of agriculture, earth moving, excavation, mining, mineral processing, and transportation. Abrasive wear contributes to significant financial cost associated with wear to the industry. The motivation for the current study was to determine whether it would be beneficial from a wear resistance perspective to produce plate steels with increased amounts of retained austenite. This thesis investigates this motivation through a material matrix containing AR400F, Abrasive (0.21 wt pct C, 1.26 wt pct Mn, 0.21 wt pct Si, 0.15 wt pct Ni, 0.18 wt pct Mo), Armor (0.46 wt pct C, 0.54 wt pct Mn, 0.36 wt pct Si, 1.74 wt pct Ni, 0.31 wt pct Mo), 9260, 301SS, Hadfield, and SAE 4325 steels. The Abrasive, Armor and 9260 steels were heat treated using different methods such as quench and temper, isothermal bainitic hold, and quench and partitioning (Q&P). These heat treatments yielded various microstructures and the test matrix allowed for investigation of steels with similar hardness and varying levels of RA. The wear test methods used consisted of dry sand rubber wheel (DSRW), impeller-tumbler impact-abrasion (impeller), and Bond abrasion wear testing. DSRW and impeller wear resistance was found to increase with hardness and retained austenite levels at certain hardness levels. Some Q&P samples exhibited similar or less wear than the Hadfield steels in DSRW and impeller tests. Scanning electron microscopy investigation of wear surfaces revealed different wear mechanisms for the different wear test methods ranging from micro-plowing, to micro-cutting and to fragmentation.

  5. Wear model simulating clinical abrasion on composite filling materials.

    PubMed

    Johnsen, Gaute Floer; Taxt-Lamolle, Sébastien F; Haugen, Håvard J

    2011-01-01

    The aim of this study was to establish a wear model for testing composite filling materials with abrasion properties closer to a clinical situation. In addition, the model was used to evaluate the effect of filler volume and particle size on surface roughness and wear resistance. Each incisor tooth was prepared with nine identical standardized cavities with respect to depth, diameter, and angle. Generic composite of 3 different filler volumes and 3 different particle sizes held together with the same resin were randomly filled in respective cavities. A multidirectional wet-grinder with molar cusps as antagonist wore the surface of the incisors containing the composite fillings in a bath of human saliva at a constant temperature of 37°C. The present study suggests that the most wear resistant filling materials should consist of medium filling content (75%) and that particles size is not as critical as earlier reported.

  6. Heat treated twin wire arc spray AISI 420 coatings under dry and wet abrasive wear

    NASA Astrophysics Data System (ADS)

    Rodriguez, E.; González, M. A.; Monjardín, H. R.; Jimenez, O.; Flores, M.; Ibarra, J.

    2017-11-01

    The influence of applying two different heat treatments such as: deep cryogenic and tempering on dry/wet abrasive wear resistance of twin wire arc spray martensitic AISI 420 coatings was evaluated by using a modified rubber wheel type test apparatus. A load dependency was observed on the abrasive wear rate behavior of both; dry and wet tests. Three body (rolling) and two body (sliding) wear mechanisms were identified in dry conditions, prevailing rolling at lower and higher loads. However, at higher loads, more presence of grooving and pits formation was observed. Coatings tempered at 205 °C/1 h displayed better wear resistance than cryogenic treated ones. A change in wear mechanism between dry and wet conditions was observed; two body wear mechanism predominated respect to three body. In both; dry and wet conditions the microstructure (several inter-splat oxides) as well as strain and residual stress promotes brittle material removal which was more evident in cryogenic and as-sprayed samples during dry test and at higher loads in wet conditions.

  7. Adhesive and abrasive wear mechanisms in ion implanted metals

    NASA Astrophysics Data System (ADS)

    Dearnaley, G.

    1985-03-01

    The distinction between adhesive and abrasive wear processes was introduced originally by Burwell during the nineteen-fifties, though some authors prefer to classify wear according to whether it is mild or severe. It is argued here that, on the basis of the performance of a variety of ion implanted metal surfaces, exposed to different modes of wear, the Burwell distinction is a valid one which, moreover, enables us to predict under which circumstances a given treatment will perform well. It is shown that, because wear rates under abrasive conditions are very sensitive to the ratio of the hardness of the surface to that of the abrasive particles, large increases in working life are attainable as a result of ion implantation. Under adhesive wear conditions, the wear rate appears to fall inversely as the hardness increases, and it is advantageous to implant species which will create and retain a hard surface oxide or other continuous film in order to reduce metal-metal contact. By the appropriate combination of physico-chemical changes in an implanted layer it has been possible to reduce wear rates by up to three orders of magnitude. Such rates compensate for the shallow depths achievable by ion implantation.

  8. The role of erosion, abrasion and attrition in tooth wear.

    PubMed

    Barbour, Michele E; Rees, Gareth D

    2006-01-01

    There is increasing clinical awareness of erosion of enamel and dentine by dietary acids and the consequent increased susceptibility to physical wear. Enamel erosion is characterized by acid-mediated surface softening that, if unchecked, will progress to irreversible loss of surface tissue, potentially exposing the underlying dentine. In comparison, dentine erosion is less well understood as the composition and microstructure are more heterogeneous. Factors which affect the erosive potential of a solution include pH, titratable acidity, common ion concentrations, and frequency and method of exposure. Abrasion and attrition are sources of physical wear and are commonly associated with tooth brushing and tooth-to-tooth contact, respectively. A combination of erosion and abrasion or attrition exacerbates wear; however, further research is required to understand the role of fluoride in protecting mineralized tissues from such processes. Abrasive wear may be seen in a wide range of patients, whereas attritive loss is usually seen in individuals with bruxism. Wear processes are implicated in the development of dentine hypersensitivity. Saliva confers the major protective function against wear due to its role in pellicle formation, buffering, acid clearance, and hard tissue remineralization. This review focuses on the physiochemical factors impacting tooth wear.

  9. Microstructure and abrasive wear properties of Fe-Cr-C hardfacing alloy cladding manufactured by Gas Tungsten Arc Welding (GTAW)

    NASA Astrophysics Data System (ADS)

    Chen, Jie-Hao; Hsieh, Chih-Chun; Hua, Pei-Shing; Chang, Chia-Ming; Lin, Chi-Ming; Wu, Paxon Ti-Yuan; Wu, Weite

    2013-01-01

    A series of Fe-Cr-C hardfacing alloys is deposited by gas tungsten arc welding and subjected to abrasive wear testing. Pure Fe with various amounts of CrC (Cr:C=4:1) powders are mixed as the fillers and used to deposit hardfacing alloys on low carbon steel. Depending on the various CrC additions to the alloy fillers, the claddings mainly contain hypoeutectic, near eutectic, or hypereutectic microstructures of austenite γ-Fe phase and (Cr,Fe)7C3 carbides on hardfacing alloys, respectively. When 30% CrC is added to the filler, the finest microstructure is achieved, which corresponds to the γ-Fe+(Cr,Fe)7C3 eutectic structure. With the addition of 35% and 40% CrC to the fillers, the results show that the cladding consists of the massive primary (Cr,Fe)7C3 as the reinforcing phase and interdendritic γ-Fe+(Cr,Fe)7C3 eutectics as the matrix. The (Cr,Fe)7C3 carbide-reinforced claddings have high hardness and excellent wear resistance under abrasive wear test conditions. Concerning the abrasive wear feature observable on the worn surface, the formation and fraction of massive primary (Cr,Fe)7C3 carbides predominates the wear resistance of hardfacing alloys. Abrasive particles result in continuous plastic grooves when the cladding has primary γ-Fe phase in a hypoeutectic structure.

  10. A Study on 3-Body Abrasive Wear Behaviour of Aluminium 8011 / Graphite Metal Matrix Composite

    NASA Astrophysics Data System (ADS)

    Latha Shankar, B.; Anil, K. C.; Patil, Rahul

    2016-09-01

    Metals and alloys have found their vital role in many applications like structural, corrosive, tribological, etc., in engineering environment. The alloys/composites having high strength to low weight ratio have gained attention of many researchers recently. In this work, graphite reinforced Aluminium 8011 metal matrix composite was prepared by conventional stir casting route, by varying the weight % of reinforcement. Uniform distribution of Graphite in matrix alloy was confirmed by optical micrographs. Prepared composite specimens were subjected to 3-body abrasive testing by varying applied load and time, the silica particles of 400 grit size were used as abrasive particles. It was observed that with the increase of weight% of Graphite the wear resistance of composite was also increasing and on comparison it was found that reinforced composite gives good wear resistance than base alloy.

  11. Influence of artificial saliva on abrasive wear and microhardness of dental composites filled with nanoparticles.

    PubMed

    Mayworm, Camila D; Camargo, Sérgio S; Bastian, Fernando L

    2008-09-01

    The aim of this study is to compare the wear resistance and hardness of two dental nanohybrid composites and to evaluate the influence of artificial saliva storage on those properties. Specimens were made from two commercial nanohybrid dental composites (Esthet-X-Dentsply and Filtek Supreme-3M). Abrasion tests were carried out in a ball-cratering machine (three body abrasion) and microscopic analysis of the wear surfaces was made using optical and scanning electron microscopy; hardness was quantified by Vickers hardness test. Those tests were repeated on specimens stored in artificial saliva. Results show that the wear rate of the studied materials is within 10(-7)mm(3)/Nmm range, one of the composites presenting wear rate twice as large as the other. After storage in artificial saliva, the wear resistance increases for both materials. Microhardness of the composites is around 52 and 64HV, Esthet-X presents higher hardness values than Filtek Supreme. After storage in artificial saliva, the microhardness of both materials decreases. Data were analyzed using ANOVA test, p < or = 0.05. Artificial saliva storage increases the materials' wear resistance, suggesting that in both materials bulk post-cure takes place and saliva absorption occurs only on the surface of the composites. This effect was confirmed by comparing the Vickers hardness before and after artificial saliva treatment and FTIR analyses. Surface microhardness of the composites decreases after storage in artificial saliva whereas bulk microhardness of the materials increases.

  12. Comparative abrasive wear resistance and surface analysis of dental resin-based materials

    PubMed Central

    Nayyer, Maleeha; Zahid, Shahreen; Hassan, Syed Hammad; Mian, Salman Aziz; Mehmood, Sana; Khan, Haroon Ahmed; Kaleem, Muhammad; Zafar, Muhammad Sohail; Khan, Abdul Samad

    2018-01-01

    Objective: The objective of this study was to assess the surface properties (microhardness and wear resistance) of various composites and compomer materials. In addition, the methodologies used for assessing wear resistance were compared. Materials and Methods: This study was conducted using restorative material (Filtek Z250, Filtek Z350, QuiXfil, SureFil SDR, and Dyract XP) to assess wear resistance. A custom-made toothbrush simulator was employed for wear testing. Before and after wear resistance, structural, surface, and physical properties were assessed using various techniques. Results: Structural changes and mass loss were observed after treatment, whereas no significant difference in terms of microhardness was observed. The correlation between atomic force microscopy (AFM) and profilometer and between wear resistance and filler volume was highly significant. The correlation between wear resistance and microhardness were insignificant. Conclusions: The AFM presented higher precision compared to optical profilometers at a nanoscale level, but both methods can be used in tandem for a more detailed and precise roughness analysis. PMID:29657526

  13. Attritional wear and abrasive surface alterations of composite resin materials in vitro.

    PubMed

    Göhring, T N; Besek, M J; Schmidlin, P R

    2002-01-01

    A laboratory study was performed with 232 specimens and 72 human enamel, 24 gold, 24 ceramic and 12 composite antagonists in 22 groups to test attritional and abrasive wear behavior of composite materials compared to wear behavior of human enamel. Belleglass HP, Concept Inlay/Onlay, Targis and Targis Upgrade 99 composite resin for lab-made restorations was tested as well as Tetric Ceram and FHC Merz light as resins for direct restorations. Natural human enamel specimens served as control. All specimens were subjected to long-term thermo-mechanical loading in a computer-controlled masticator, chemical degradation and toothbrush/toothpaste abrasion. Wear of specimen in occlusal contact area (OCA), contact-free occlusal area and wear of natural enamel cusps as well as antagonists made of gold, ceramic and composite in identical form was measured after 120,000, 240,000, 640,000 and 1200,000 load cycles. A qualitative SEM analysis was performed to support quantitative data. Belleglass HP and Targis Upgrade 99 restorative materials showed wear resistance comparable to human enamel when loaded with enamel cusps. Wear of Targis versus composite and gold antagonists was significantly higher (p<0.0001). Analysis of surface alterations showed hygroscopic expansion in all composite resins during the test. As a consequence of this study, necessity to further improve physical properties of composites for long lasting restorations was obvious. Beside of attritional wear in OCA, attention must be given to stable filler-matrix interfaces and prevention of water sorption.

  14. The influence of aluminum and carbon on the abrasion resistance of high manganese steels

    NASA Astrophysics Data System (ADS)

    Buckholz, Samuel August

    Abrasive wear testing of lightweight, austenitic Fe-Mn-Al-C cast steel has been performed in accordance with ASTM G65 using a dry sand, rubber wheel, abrasion testing apparatus. Testing was conducted on a series of Fe-30Mn-XAl-YC-1Si-0.5Mo chemistries containing aluminum levels from 2.9 to 9.5 wt.% and carbon levels from 0.9 to 1.83 wt.%. Solution treated materials having an austenitic microstructure produced the highest wear resistance. Wear resistance decreased with higher aluminum, lower carbon, and higher hardness after age hardening. In the solution treated condition the wear rate was a strong function of the aluminum to carbon ratio and the wear rate increased with a parabolic dependence on the Al/C ratio, which ranged from 1.8 to 10.2. Examination of the surface wear scar revealed a mechanism of plowing during abrasion testing and this method of material removal is sensitive to work hardening rate. Work hardening behavior was determined from tensile tests and also decreased with increasing Al/C ratio and after aging hardening. The loss of wear resistance is related to short range ordering of Al and C in the solution treated materials and kappa-carbide precipitation in age hardened materials and both contribute to planar slip and lower work hardening rates. A high carbon tool steel (W1) and a bainitic low alloy steel (SAE 8620) were also tested for comparison. A lightweight steel containing 6.5 wt.% Al and 1.2 wt.% C has wear resistance comparable to within 5% of the bainitic SAE 8620 steel forging currently used for the Bradley Fighting Vehicle track shoe and this cast Fe-Mn-Al-C steel, at equivalent tensile properties, would be 10% lighter.

  15. Wear resistance of metals and alloys; Proceedings of the Conference, Chicago, IL, Sept. 24-30, 1988

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kingsbury, G.R.

    1988-01-01

    Techniques for characterizing and improving the wear properties of metals and composites are discussed in reviews and reports. Topics addressed include the use of interatomic potentials to study the relationship between abrasive wear and other mechanical properties, gas-detonation powder spraying of diamond coatings, a fluidized-bed test method for erosion resistance, the wear behavior of Al and Al-Si-Cu alloys, and abrasive wear of bronze and ZA alloys with and without lubrication. Consideration is given to continuously cast vs sand-cast Zn-Al alloys for bearings, sintered 6061 Al-alloy-based particulate composites with dry lubricants, Cu-based particulate composites, high-temperature friction and wear of X-750 andmore » X-188 superalloys for low-heat-rejection engines, a new metallurgical conception of wear-resistant steels, and the effect of matrix microstructure on the abrasion resistance of high-Cr white cast irons. Extensive graphs and micrographs are provided.« less

  16. Prediction Of Abrasive And Diffusive Tool Wear Mechanisms In Machining

    NASA Astrophysics Data System (ADS)

    Rizzuti, S.; Umbrello, D.

    2011-01-01

    Tool wear prediction is regarded as very important task in order to maximize tool performance, minimize cutting costs and improve the quality of workpiece in cutting. In this research work, an experimental campaign was carried out at the varying of cutting conditions with the aim to measure both crater and flank tool wear, during machining of an AISI 1045 with an uncoated carbide tool P40. Parallel a FEM-based analysis was developed in order to study the tool wear mechanisms, taking also into account the influence of the cutting conditions and the temperature reached on the tool surfaces. The results show that, when the temperature of the tool rake surface is lower than the activation temperature of the diffusive phenomenon, the wear rate can be estimated applying an abrasive model. In contrast, in the tool area where the temperature is higher than the diffusive activation temperature, the wear rate can be evaluated applying a diffusive model. Finally, for a temperature ranges within the above cited values an adopted abrasive-diffusive wear model furnished the possibility to correctly evaluate the tool wear phenomena.

  17. The study of microstructure of wear-resistant coatings applied for protection from abrasive wear of horizontal and tilt drilling drill bits

    NASA Astrophysics Data System (ADS)

    Markova, I. Yu; Zakharova, E. S.; Maslov, A. L.; Polushin, N. I.; Laptev, A. I.; SOvchinnikova, M.

    2017-05-01

    Drill bits of the cutting type over the period of their existence have undergone significant changes - from the use of carbide cutters to diamond composite PDC elements, in which the diamond layer is applied to a hardmetal substrate. Using such elements, it was possible to significantly increase the service life of the drill bits, however, during work, there is a significant abrasive deterioration of the bit body, which does not fully realize the advantages of PDC elements. Therefore, to protect the body from wear use special wear-resistant coatings. This work is devoted to research of microstructural coatings, namely coatings brands WokaDur NiA, HR-6750, HR-6750 with sublayer Rock Dur 47 on various steel substrates which applied by the gas-thermal spraying in Ltd “Oerlikon Metko Rus”. They were examined with the use of scanning electron microscopy, X-ray phase analysis and a Vickers micro-hardness tester. It was established that the microhardness of the coating matrix is 590-660 HV, and the microhardness of tungsten carbide particles reinforcing the coating, is 2145-2455 HV.

  18. Wear resistance of ductile irons

    NASA Astrophysics Data System (ADS)

    Lerner, Y. S.

    1994-06-01

    This study was undertaken to evaluate the wear resistance of different grades of ductile iron as alterna-tives to high- tensile- strength alloyed and inoculated gray irons and bronzes for machine- tool and high-pressure hydraulic components. Special test methods were employed to simulate typical conditions of reciprocating sliding wear with and without abrasive- contaminated lubricant for machine and press guideways. Quantitative relationships were established among wear rate, microstructure and micro-hardness of structural constituents, and nodule size of ductile iron. The frictional wear resistance of duc-tile iron as a bearing material was tested with hardened steel shafts using standard test techniques under continuous rotating movement with lubricant. Lubricated sliding wear tests on specimens and compo-nents for hydraulic equipment and apparatus were carried out on a special rig with reciprocating motion, simulating the working conditions in a piston/cylinder unit in a pressure range from 5 to 32 MPa. Rig and field tests on machine- tool components and units and on hydraulic parts have confirmed the test data.

  19. Investigation into the mechanisms of closed three-body abrasive wear

    NASA Astrophysics Data System (ADS)

    Dwyer-Joyce, R. S.; Sayles, R. S.; Ioannides, E.

    1994-06-01

    Contacting components frequently fail by abrasion caused by solid contaminants in the lubricant. This process can be classified as a closed three-body abrasive wear process. The mechanisms by which trapped particles cause material removal are not fully understood. This paper describes tests using model elastohydrodynamic contacts to study these mechanisms. An optical elastohydrodynamic lubrication rig has been used to study the deformation and fracture of ductile and brittle lubricant-borne debris. A ball-on-disk machine was used to study the behavior of the particles in partially sliding contacts. Small diamond particles were used as abrasives since these were thought not to break down in the contact; wear could then be directly related to particles of a known size. The particles were found to embed in the softer surface and to scratch the harder. The mass of material worn from the ball surface was approximately proportional to the particle sliding distance and abrasive concentration. Small particles tumbled through the contact, while larger particles ploughed. Mass loss was found to increase with abrasive particle size. Individual abrasion scratches have been measured and related to the abrading particle. A simple model of the abrasive process has been developed and compared with experimental data. The discrepancies are thought to be the result of the uncertainty about the entrainment of particles into the contact.

  20. Characterization of the Micro-Abrasive Wear in Coatings of TaC-HfC/Au for Biomedical Implants

    PubMed Central

    Guzmán, Pablo; Yate, Luis; Sandoval, Mercy; Caballero, Jose

    2017-01-01

    The object of this work was the deposition of a Ta-Hf-C thin film with a gold interlayer on stainless steel, via the physical vapor deposition (PVD) technique, in order to evaluate the properties of different systems subjected to micro-abrasive wear phenomena generated by alumina particles in Ringer's solution. The surface characterization was performed using a scanning electron microscope (SEM) and atomic force microscope (AFM). The crystallographic phases exhibited for each coating were obtained by X-ray diffraction (XRD). As a consequence of modifying the composition of Ta-Hf there was evidence of an improvement in the micro-abrasive wear resistance and, for each system, the wear constants that confirm the enhancement of the surface were calculated. Likewise, these surfaces can be bioactive, generating an alternative to improve the biological fixation of the implants, therefore, the coatings of TaC-HfC/Au contribute in the development of the new generation of orthopedic implants. PMID:28773207

  1. Dental Wear: Attrition, Erosion, and Abrasion-A Palaeo-Odontological Approach.

    PubMed

    Sperber, Geoffrey H

    2017-06-17

    This paper reviews the surface ablation of early hominin teeth by attrition, abrasion, and erosive dental wear. The occurrence of these lesions is explored in a sample of South African fossil australopithecine dentitions revealing excessive wear. Interpretation of the nature of the dietary components causing such wear in the absence of carious erosion provides insight into the ecology of the Plio-pleistocene epoch (1-2 million years ago). Fossil teeth inform much of the living past by their retained evidence after death. Tooth wear is the ultimate forensic dental evidence of lives lived.

  2. Selection criteria for wear resistant powder coatings under extreme erosive wear conditions

    NASA Astrophysics Data System (ADS)

    Kulu, P.; Pihl, T.

    2002-12-01

    Wear-resistant thermal spray coatings for sliding wear are hard but brittle (such as carbide and oxide based coatings), which makes them useless under impact loading conditions and sensitive to fatigue. Under extreme conditions of erosive wear (impact loading, high hardness of abrasives, and high velocity of abradant particles), composite coatings ensure optimal properties of hardness and toughness. The article describes tungsten carbide-cobalt (WC-Co) systems and self-fluxing alloys, containing tungsten carbide based hardmetal particles [NiCrSiB-(WC-Co)] deposited by the detonation gun, continuous detonation spraying, and spray fusion processes. Different powder compositions and processes were studied, and the effect of the coating structure and wear parameters on the wear resistance of coatings are evaluated. The dependence of the wear resistance of sprayed and fused coatings on their hardness is discussed, and hardness criteria for coating selection are proposed. The so-called “double cemented” structure of WC-Co based hardmetal or metal matrix composite coatings, as compared with a simple cobalt matrix containing particles of WC, was found optimal. Structural criteria for coating selection are provided. To assist the end user in selecting an optimal deposition method and materials, coating selection diagrams of wear resistance versus hardness are given. This paper also discusses the cost-effectiveness of coatings in the application areas that are more sensitive to cost, and composite coatings based on recycled materials are offered.

  3. Study of abrasive resistance of foundries models obtained with use of additive technology

    NASA Astrophysics Data System (ADS)

    Ol'khovik, Evgeniy

    2017-10-01

    A problem of determination of resistance of the foundry models and patterns from ABS (PLA) plastic, obtained by the method of 3D printing with using FDM additive technology, to abrasive wear and resistance in the environment of foundry sand mould is considered in the present study. The description of a technique and equipment for tests of castings models and patterns for wear is provided in the article. The manufacturing techniques of models with the use of the 3D printer (additive technology) are described. The scheme with vibration load was applied to samples tests. For the most qualitative research of influence of sandy mix on plastic, models in real conditions of abrasive wear have been organized. The results also examined the application of acrylic paintwork to the plastic model and a two-component coating. The practical offers and recommendation on production of master models with the use of FDM technology allowing one to reach indicators of durability, exceeding 2000 cycles of moulding in foundry sand mix, are described.

  4. Effect of Experimental Variables of Abrasive Wear on 3D Surface Roughness and Wear Rate of Al-4.5 % Cu Alloy

    NASA Astrophysics Data System (ADS)

    Ghosh, Debashis; Mallik, Manab; Mandal, Nilrudra; Dutta, Samik; Roy, Himadri; Lohar, Aditya Kumar

    2017-04-01

    This investigation was primarily carried out to examine the abrasive wear behavior of as cast Al-4.5 % Cu alloy. Wear tests have been carried out using an abrasive wear machine with emery paper embedded with SiC particles acting as abrasive medium. The experiments were planned using central composite design, with, load, cycle and grit size as input variables, whereas wear rate and 3D roughness were considered as output variable. Analysis of variance was applied to check the adequacy of the mathematical model and their respective parameters. Microstructural investigations of the worn surfaces have been carried out to explain the observed results and to understand the wear micro-mechanisms as per the planned experiments. Desirability function optimization technique was finally employed to optimize the controlling factors. The observed results revealed that, grit size plays a significant role in the variation of wear rate and 3D roughness as compared to load and cycles. Based on the significance of interactions, the regression equations were derived and verified further with a number of confirmation runs to assess the adequacy of the model. A close agreement (±10 %) between the predicted and experimentally measured results was obtained from this investigation.

  5. Tooth wear: attrition, erosion, and abrasion.

    PubMed

    Litonjua, Luis A; Andreana, Sebastiano; Bush, Peter J; Cohen, Robert E

    2003-06-01

    Attrition, erosion, and abrasion result in alterations to the tooth and manifest as tooth wear. Each classification acts through a distinct process that is associated with unique clinical characteristics. Accurate prevalence data for each classification are not available since indices do not necessarily measure one specific etiology, or the study populations may be too diverse in age and characteristics. The treatment of teeth in each classification will depend on identifying the factors associated with each etiology. Some cases may require specific restorative procedures, while others will not require treatment. A review of the literature points to the interaction of the three entities in the initiation and progression of lesions that may act synchronously or sequentially, synergistically or additively, or in conjunction with other entities to mask the true nature of tooth wear, which appears to be multifactorial.

  6. Effect of consolidation on adhesive and abrasive wear of ultra high molecular weight polyethylene.

    PubMed

    Gul, Rizwan M; McGarry, Frederick J; Bragdon, Charles R; Muratoglu, Orhun K; Harris, William H

    2003-08-01

    Total hip replacement (THR) is widely performed to recover hip joint functions lost by trauma or disease and to relieve pain. The major cause of failure in THR is the wear of the ultra high molecular weight polyethylene (UHMWPE) component. The dominant wear mechanism in THR occurs through adhesion and abrasion. While poor consolidation of UHMWPE is known to increase the incidence of a different damage mode, delamination, which is the dominant wear mechanism in tibial inserts but uncommon in THR, the effect of consolidation on adhesive and abrasive wear of UHMWPE is not clear. In this study UHMWPE resin was subjected to hot isostatic pressing under a pressure of 138MPa at different temperatures (210 degrees C, 250 degrees C, and 300 degrees C) to achieve varying degrees of consolidation. The extent of consolidation was determined by optical microscopy using thin sections, and by scanning electron microscopy using cryofractured and solvent etched specimens. Wear behavior of the samples with varying degree of consolidation was determined using a bi-directional pin-on-disc machine simulating conditions in a hip joint. Increasing the processing temperature decreased the incidence of fusion defects and particle boundaries reflecting the powder flakes of the virgin resin, improving the consolidation. However, the bi-directional pin-on-disc wear rate did not change with the processing temperature, indicating that adhesive and abrasive wear is independent of the extent of consolidation in the range of parameters studied here.

  7. Structure and properties of corrosion and wear resistant Cr-Mn-N steels

    NASA Astrophysics Data System (ADS)

    Lenel, U. R.; Knott, B. R.

    1987-06-01

    Steels containing about 12 pct Cr, 10 pct Mn, and 0.2 pct N have been shown to have an unstable austenitic microstructure and have good ductility, extreme work hardening, high fracture strength, excellent toughness, good wear resistance, and moderate corrosion resistance. A series of alloys containing 9.5 to 12.8 pct Cr, 5.0 to 10.4 pct Mn, 0.16 to 0.32 pct N, 0.05 pct C, and residual elements typical of stainless steels was investigated by microstructural examination and mechanical, abrasion, and corrosion testing. Microstructures ranged from martensite to unstable austenite. The unstable austenitic steels transformed to α martensite on deformation and displayed very high work hardening, exceeding that of Hadfield’s manganese steels. Fracture strengths similar to high carbon martensitic stainless steels were obtained while ductility and toughness values were high, similar to austenitic stainless steels. Resistance to abrasive wear exceeded that of commercial abrasion resistant steels and other stainless steels. Corrosion resistance was similar to that of other 12 pct Cr steels. Properties were not much affected by minor compositional variations or rolled-in nitrogen porosity. In 12 pct Cr-10 pct Mn alloys, ingot porosity was avoided when nitrogen levels were below 0.19 pet, and austenitic microstructures were obtained when nitrogen levels exceeded 0.14 pct.

  8. Nanoclay-Reinforced Glass-Ionomer Cements: In Vitro Wear Evaluation and Comparison by Two Wear-Test Methods

    PubMed Central

    Fareed, Muhammad A.; Stamboulis, Artemis

    2017-01-01

    Glass ionomer cement (GIC) represents a major transformation in restorative dentistry. Wear of dental restoratives is a common phenomenon and the determination of the wear resistance of direct-restorative materials is a challenging task. The aim of this paper was to evaluate the wear resistance of novel glass ionomer cement by two wear-test methods and to compare the two wear methods.The wear resistance of a conventional glass ionomer cement (HiFi Advanced Health Care Kent, UK) and cements modified by including various percentages of nanoclays (1, 2 and 4 wt %) was measured by a reciprocating wear test (ball-on-flat) and Oregon Health and Sciences University’s (OHSU) wear simulator. The OHSU wear simulation subjected the cement specimens to three wear mechanisms, namely abrasion, three-body abrasion and attrition using a steatite antagonist. The abrasion wear resulted in material loss from GIC specimen as the steatite antagonist forced through the exposed glass particles when it travelled along the sliding path.The hardness of specimens was measured by the Vickers hardness test. The results of reciprocation wear test showed that HiFi-1 resulted in the lowest wear volume 4.90 (0.60) mm3 (p < 0.05), but there was no significant difference (p > 0.05) in the wear volume in comparison to HiFi, HiFi-2 and HiFi-4. Similarly, the results of OHSU wear simulator showed that the total wear volume of HiFi-4 1.49 (0.24) was higher than HiFi-1 and HiFi-2. However, no significant difference (p > 0.05) was found in the OHSU total wear volume in GICs after nanoclay incorporation. The Vickers hardness (HV) of the nanoclay-reinforced cements was measured between 62 and 89 HV. Nanoclay addition at a higher concentration (4%) resulted in higher wear volume and wear depth. The total wear volumes were less dependent upon abrasion volume and attrition volume. The total wear depths were strongly influenced by attrition depth and to some extent by abrasion depth. The addition of nanoclay

  9. Study on Abrasive Wear of Brake Pad in the Large-megawatt Wind Turbine Brake Based on Deform Software

    NASA Astrophysics Data System (ADS)

    Zhang, Shengfang; Hao, Qiang; Sha, Zhihua; Yin, Jian; Ma, Fujian; Liu, Yu

    2017-12-01

    For the friction and wear issues of brake pads in the large-megawatt wind turbine brake during braking, this paper established the micro finite element model of abrasive wear by using Deform-2D software. Based on abrasive wear theory and considered the variation of the velocity and load in the micro friction and wear process, the Archard wear calculation model is developed. The influence rules of relative sliding velocity and friction coefficient in the brake pad and disc is analysed. The simulation results showed that as the relative sliding velocity increases, the wear will be more serious, while the larger friction coefficient lowered the contact pressure which released the wear of the brake pad.

  10. Micro-scale abrasive wear behavior of medical implant material Ti-25Nb-3Mo-3Zr-2Sn alloy on various friction pairs.

    PubMed

    Wang, Zhenguo; Huang, Weijiu; Ma, Yanlong

    2014-09-01

    The micro-scale abrasion behaviors of surgical implant materials have often been reported in the literature. However, little work has been reported on the micro-scale abrasive wear behavior of Ti-25Nb-3Mo-3Zr-2Sn (TLM) titanium alloy in simulated body fluids, especially with respect to friction pairs. Therefore, a TE66 Micro-Scale Abrasion Tester was used to study the micro-scale abrasive wear behavior of the TLM alloy. This study covers the friction coefficient and wear loss of the TLM alloy induced by various friction pairs. Different friction pairs comprised of ZrO2, Si3N4 and Al2O3 ceramic balls with 25.4mm diameters were employed. The micro-scale abrasive wear mechanisms and synergistic effect between corrosion and micro-abrasion of the TLM alloy were investigated under various wear-corrosion conditions employing an abrasive, comprised of SiC (3.5 ± 0.5 μm), in two test solutions, Hanks' solution and distilled water. Before the test, the specimens were heat treated at 760°C/1.0/AC+550°C/6.0/AC. It was discovered that the friction coefficient values of the TLM alloy are larger than those in distilled water regardless of friction pairs used, because of the corrosive Hanks' solution. It was also found that the value of the friction coefficient was volatile at the beginning of wear testing, and it became more stable with further experiments. Because the ceramic balls have different properties, especially with respect to the Vickers hardness (Hv), the wear loss of the TLM alloy increased as the ball hardness increased. In addition, the wear loss of the TLM alloy in Hanks' solution was greater than that in distilled water, and this was due to the synergistic effect of micro-abrasion and corrosion, and this micro-abrasion played a leading role in the wear process. The micro-scale abrasive wear mechanism of the TLM alloy gradually changed from two-body to mixed abrasion and then to three-body abrasion as the Vickers hardness of the balls increased. Copyright

  11. Abrasion Resistance of Nano Silica Modified Roller Compacted Rubbercrete: Cantabro Loss Method and Response Surface Methodology Approach

    NASA Astrophysics Data System (ADS)

    Adamu, Musa; Mohammed, Bashar S.; Shafiq, Nasir

    2018-04-01

    Roller compacted concrete (RCC) when used for pavement is subjected to skidding/rubbing by wheels of moving vehicles, this causes pavement surface to wear out and abrade. Therefore, abrasion resistance is one of the most important properties of concern for RCC pavement. In this study, response surface methodology was used to design, evaluate and analyze the effect of partial replacement of fine aggregate with crumb rubber, and addition of nano silica on the abrasion resistance of roller compacted rubbercrete (RCR). RCR is the terminology used for RCC pavement where crumb rubber was used as partial replacement to fine aggregate. The Box-Behnken design method was used to develop the mixtures combinations using 10%, 20%, and 30% crumb rubber with 0%, 1%, and 2% nano silica. The Cantabro loss method was used to measure the abrasion resistance. The results showed that the abrasion resistance of RCR decreases with increase in crumb rubber content, and increases with increase in addition of nano silica. The analysis of variance shows that the model developed using response surface methodology (RSM) has a very good degree of correlation, and can be used to predict the abrasion resistance of RCR with a percentage error of 5.44%. The combination of 10.76% crumb rubber and 1.59% nano silica yielded the best combinations of RCR in terms of abrasion resistance of RCR.

  12. Wear Behavior of an Ultra-High-Strength Eutectoid Steel

    NASA Astrophysics Data System (ADS)

    Mishra, Alok; Maity, Joydeep

    2018-02-01

    Wear behavior of an ultra-high-strength AISI 1080 steel developed through incomplete austenitization-based combined cyclic heat treatment is investigated in comparison with annealed and conventional hardened and tempered conditions against an alumina disk (sliding speed = 1 m s-1) using a pin-on-disk tribometer at a load range of 7.35-14.7 N. On a gross scale, the mechanism of surface damage involves adhesive wear coupled with abrasive wear (microcutting effects in particular) at lower loads. At higher loads, mainly the abrasive wear (both microcutting and microploughing mechanisms) and evolution of adherent oxide are observed. Besides, microhardness of matrix increases with load indicating substantial strain hardening during wear test. The rate of overall wear is found to increase with load. As-received annealed steel with the lowest initial hardness suffers from severe abrasive wear, thereby exhibiting the highest wear loss. Such a severe wear loss is not observed in conventional hardened and tempered and combined cyclic heat treatment conditions. Combined cyclic heat-treated steel exhibits the greatest wear resistance (lowest wear loss) due to its initial high hardness and evolution of hard abrasion-resistant tribolayer during wear test at higher load.

  13. Abrasion of eroded and sound enamel by a dentifrice containing diamond abrasive particles

    PubMed

    Wegehaupt, Florian J.; Hoegger, Vanessa G. M.; Attin, Thomas

    2017-07-24

    Eroded enamel is more susceptible to abrasive wear than sound enamel. New toothpastes utilizing diamond particles as abrasives have been developed. The present study investigated the abrasive wear of eroded enamel by three commercially available toothpastes (one containing diamond particles) and compared it to the respective wear of sound enamel caused by these toothpastes. Seventy-two bovine enamel samples were randomly allocated to six groups (S1–S3 and E1–E3; n=12). Samples were submitted to an abrasive (S1–S3) or erosion plus abrasion (E1–E3) cycling. Per cycle, all samples were brushed (abrasion; 20 brushing stokes) with the following toothpastes: S1/E1: Signal WHITE SYSTEM, S2/E2: elmex KARIESSCHUTZ and S3-E3: Candida WHITE DIAMOND (diamond particles). Groups E1–E3 were additionally eroded with HCl (pH 3.0) for 2 min before each brushing procedure. After 30, 60 and 90 cycles enamel wear was measured by surface profilometry. Within the same toothpaste and same number of cycles, enamel wear due to erosion plus abrasion was significantly higher than due to mere abrasion. After 30, 60 and 90 cycles, no significant difference in the wear in groups S1 and S2 was observed while the wear in group E1 was significantly (p<0.05, ANOVA, Scheffecyc) lower than that in group E2. After 90 cycles, wear in group S3 was about 5 times higher than that in group S2, while wear in group E3 was about 1.3 times higher than that in group E2. As compared to the other two investigated toothpastes, the dentifrice containing diamond particles caused slightly higher abrasive wear of eroded enamel and distinctly higher wear of sound enamel compared to the conventional toothpastes under investigation.

  14. Abrasion of acrylic veneers by simulated toothbrushing.

    PubMed

    Xu, H C; Söremark, R; Wiktorsson, G; Wang, T; Liu, W Y

    1984-12-01

    The abrasion responses were tested on four acrylic veneer materials, K + B Plus, K + B 75, Isosit, and Ivocron. The studies were performed in two independent research laboratories. Two different brushing machines were used with an abrasive slurry. The results were used for comparing the degree of abrasion for the resin materials. Three analytical methods of measuring the degree of abrasive wear were used: surface profile measurement, microscopic evaluation, and measurement of loss of volume. Isosit showed the best abrasion resistance of the four materials tested.

  15. Wear Resistance of Austempered Ductile Iron with Nanosized Additives

    NASA Astrophysics Data System (ADS)

    Kaleicheva, J. K.; Mishev, V.

    2018-01-01

    The wear resistance, microstructure and mechanical properties of austempered ductile iron (ADI) with nanosized additives of cubic boron nitride cBN are investigated. Samples of ductile iron are put under austhempering at the following conditions: heating at 900°С, 1 h and isothermal retention at 280оС, 2 h and 380°С, 2 h with the aim to achieve a lower bainitic structure and an upper bainitic structure. The experimental wear testing of austempered ductile irons is performed in friction conditions of a fixed abrasive by a cinematic scheme „pin - disc” using an accelerated testing method and device. The microstructure of the ADI is investigated by metallographic and X-Ray analyses. The Vickers hardness testing and impact strength examination are carried out. The influence of the nanosized additives of cBN on the wear resistance, microstructure, impact strength and hardness of the ADI is investigated.

  16. Microstructure and abrasive wear test of different composite layers formed by laser coating

    NASA Astrophysics Data System (ADS)

    Bartos, J.

    1994-09-01

    Layers containing different particles of different sizes (TiC: 2,7 micrometers and 31 micrometers mid size; TaC: 15 micrometers mid size) were formed on the surface of 90 MnCrV8 tool steel. A CO2-gas laser equipment was used to form these layers. The grain contents of the layers were between 35% - 55%. Some of the ready TiC layers were hardened by laser in order to reduce the retained amount. We compared the wear resistance of the layers employing abrasive wheel test. For reference purposes we carried out the test of traditionally hardened, traded TICALLOY II and TICALLOY W materials as well.

  17. Effect of distribution of striated laser hardening tracks on dry sliding wear resistance of biomimetic surface

    NASA Astrophysics Data System (ADS)

    Su, Wei; Zhou, Ti; Zhang, Peng; Zhou, Hong; Li, Hui

    2018-01-01

    Some biological surfaces were proved to have excellent anti-wear performance. Being inspired, Nd:YAG pulsed laser was used to create striated biomimetic laser hardening tracks on medium carbon steel samples. Dry sliding wear tests biomimetic samples were performed to investigate specific influence of distribution of laser hardening tracks on sliding wear resistance of biomimetic samples. After comparing wear weight loss of biomimetic samples, quenched sample and untreated sample, it can be suggested that the sample covered with dense laser tracks (3.5 mm spacing) has lower wear weight loss than the one covered with sparse laser tracks (4.5 mm spacing); samples distributed with only dense laser tracks or sparse laser tracks (even distribution) were proved to have better wear resistance than samples distributed with both dense and sparse tracks (uneven distribution). Wear mechanisms indicate that laser track and exposed substrate of biomimetic sample can be regarded as hard zone and soft zone respectively. Inconsecutive striated hard regions, on the one hand, can disperse load into small branches, on the other hand, will hinder sliding abrasives during wear. Soft regions with small range are beneficial in consuming mechanical energy and storing lubricative oxides, however, soft zone with large width (>0.5 mm) will be harmful to abrasion resistance of biomimetic sample because damages and material loss are more obvious on surface of soft phase. As for the reason why samples with even distributed bionic laser tracks have better wear resistance, it can be explained by the fact that even distributed laser hardening tracks can inhibit severe worn of local regions, thus sliding process can be more stable and wear extent can be alleviated as well.

  18. Wear resistance of WC/Co HVOF-coatings and galvanic Cr coatings modified by diamond nanoparticles

    NASA Astrophysics Data System (ADS)

    Kandeva, M.; Grozdanova, T.; Karastoyanov, D.; Assenova, E.

    2017-02-01

    The efforts in the recent 20 years are related to search of ecological solutions in the tribotechnologies for the replacement of galvanic Cr coatings in the contact systems operating under extreme conditions: abrasion, erosion, cavitation, corrosion, shock and vibration loads. One of the solutions is in the composite coatings deposited by high velocity gas-flame process (HVOF). The present paper presents comparative study results for mechanical and tribological characteristics of galvanic Cr coatings without nanoparticles, galvanic Cr coatings modified by diamond nanoparticles NDDS of various concentration 0.6; 10; 15 и 20% obtained under three technological regimes, and composite WC-12Co coating. Comparative results about hardness, wear, wear resistance and friction coefficient are obtained for galvanic Cr-NDDS and WC-12Co coatings operating at equal friction conditions of dry friction on abrasive surface. The WC-12Co coating shows 5.4 to 7 times higher wear resistance compared to the galvanic Cr-NDDS coatings.

  19. Microstructure, Mechanical Properties, and Two-Body Abrasive Wear Behavior of Cold-Sprayed 20 vol.% Cubic BN-NiCrAl Nanocomposite Coating

    NASA Astrophysics Data System (ADS)

    Luo, Xiao-Tao; Yang, Er-Juan; Shang, Fu-Lin; Yang, Guan-Jun; Li, Chen-Xin; Li, Chang-Jiu

    2014-10-01

    20 vol.% cubic boron nitride (cBN) dispersoid reinforced NiCrAl matrix nanocomposite coating was prepared by cold spray using mechanically alloyed nanostructured composite powders. The as-sprayed nanocomposite coating was annealed at a temperature of 750 °C to enhance the inter-particle bonding. Microstructure of spray powders and coatings was characterized. Vickers microhardness of the coatings was measured. Two-body abrasive wear behavior of the coatings was examined on a pin-on-disk test. It was found that, in mechanically alloyed composite powders, nano-sized and submicro-sized cBN particles are uniformly distributed in nanocrystalline NiCrAl matrix. Dense coating was deposited by cold spray at a gas temperature of 650 °C with the same phases and grain size as those of the starting powder. Vickers hardness test yielded a hardness of 1063 HV for the as-sprayed 20 vol.% cBN-NiCrAl coating. After annealed at 750 °C for 5 h, unbonded inter-particle boundaries were partially healed and evident grain growth of nanocrystalline NiCrAl was avoided. Wear resistance of the as-sprayed 20 vol.% cBN-NiCrAl nanocomposite coating was comparable to the HVOF-sprayed WC-12Co coating. Annealing of the nanocomposite coating resulted in the improvement of wear resistance by a factor of ~33% owing to the enhanced inter-particle bonding. Main material removal mechanisms during the abrasive wear are also discussed.

  20. Abrasion resistant coating and method of making the same

    DOEpatents

    Sordelet, Daniel J.; Besser, Matthew F.

    2001-06-05

    An abrasion resistant coating is created by adding a ductile phase to a brittle matrix phase during spray coating where an Al--Cu--Fe quasicrystalline phase (brittle matrix) and an FeAl intermetallic (ductile phase) are combined. This composite coating produces a coating mostly of quasicrystal phase and an inter-splat layer of the FeAl phase to help reduce porosity and cracking within the coating. Coatings are prepared by plasma spraying unblended and blended quasicrystal and intermetallic powders. The blended powders contain 1, 5, 10 and 20 volume percent of the intermetallic powders. The unblended powders are either 100 volume percent quasicrystalline or 100 volume percent intermetallic; these unblended powders were studied for comparison to the others. Sufficient ductile phase should be added to the brittle matrix to transform abrasive wear mode from brittle fracture to plastic deformation, while at the same time the hardness of the composite should not be reduced below that of the original brittle phase material.

  1. Tribological tests of wear-resistant coatings used in the production of drill bits of horizontal and inclined drilling

    NASA Astrophysics Data System (ADS)

    Maslov, A. L.; Markova, I. Yu; Zakharova, E. S.; Polushin, N. I.; Laptev, A. I.

    2017-05-01

    It is known that modern drilling bit body undergoes significant abrasive wear in the contact area with the solid and the retracted cuttings. For protection of the body rationally use wear-resistant coating, which is welded directly to the body of bit. Before mass use of the developed coverings they need to be investigated by various methods that it was possible to characterize coatings and on the basis of the obtained data to perform optimization of both composition of coatings and technology. Such methods include microstructural studies tribological tests, crack resistance and others. This work is devoted to the tribological tests of imported brand of coatings WokaDur NiA and and domestic brand of coating HR-6750 (both brands manufactured by Ltd “Oerlikon Metco Rus”), used to protect the bit body from abrasive wear.

  2. Increasing the wear resistance of ultra-high molecular weight polyethylene by adding solid lubricating fillers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Panin, S. V., E-mail: svp@ispms.tsc.ru; Kornienko, L. A.; Poltaranin, M. A.

    2014-11-14

    In order to compare effectiveness of adding solid lubricating fillers for polymeric composites based on ultra-high molecular weight polyethylene (UHMWPE) with graphite, molybdenum disulfide and polytetrafluoroethylene, their tribotechnical characteristics under dry friction, boundary lubrication and abrasive wearing were investigated. The optimal weight fractions of fillers in terms of improving wear resistance have been determined. The supramolecular structure and topography of wear track surfaces of UHMWPE-based composites with different content of fillers have been studied.

  3. Abrasion and fatigue resistance of PDMS containing multiblock polyurethanes after accelerated water exposure at elevated temperature.

    PubMed

    Chaffin, Kimberly A; Wilson, Charles L; Himes, Adam K; Dawson, James W; Haddad, Tarek D; Buckalew, Adam J; Miller, Jennifer P; Untereker, Darrel F; Simha, Narendra K

    2013-11-01

    Segmented polyurethane multiblock polymers containing polydimethylsiloxane and polyether soft segments form tough and easily processed thermoplastic elastomers (PDMS-urethanes). Two commercially available examples, PurSil 35 (denoted as P35) and Elast-Eon E2A (denoted as E2A), were evaluated for abrasion and fatigue resistance after immersion in 85 °C buffered water for up to 80 weeks. We previously reported that water exposure in these experiments resulted in a molar mass reduction, where the kinetics of the hydrolysis reaction is supported by a straight forward Arrhenius analysis over a range of accelerated temperatures (37-85 °C). We also showed that the ultimate tensile properties of P35 and E2A were significantly compromised when the molar mass was reduced. Here, we show that the reduction in molar mass also correlated with a reduction in both the abrasion and fatigue resistance. The instantaneous wear rate of both P35 and E2A, when exposed to the reciprocating motion of an ethylene tetrafluoroethylene (ETFE) jacketed cable, increased with the inverse of the number averaged molar mass (1/Mn). Both materials showed a change in the wear surface when the number-averaged molar mass was reduced to ≈ 16 kg/mole, where a smooth wear surface transitioned to a 'spalling-like' pattern, leaving the wear surface with ≈ 0.3 mm cracks that propagated beyond the contact surface. The fatigue crack growth rate for P35 and E2A also increased in proportion to 1/Mn, after the molar mass was reduced below a critical value of ≈30 kg/mole. Interestingly, this critical molar mass coincided with that at which the single cycle stress-strain response changed from strain hardening to strain softening. The changes in both abrasion and fatigue resistance, key predictors for long term reliability of cardiac leads, after exposure of this class of PDMS-urethanes to water suggests that these materials are susceptible to mechanical compromise in vivo. Copyright © 2013 The Authors

  4. Plasma immersion ion implantation on 15-5PH stainless steel: influence on fatigue strength and wear resistance

    NASA Astrophysics Data System (ADS)

    Bonora, R.; Cioffi, M. O. H.; Voorwald, H. J. C.

    2017-05-01

    Surface improvement in steels is of great interest for applications in industry. The aim of this investigation is to study the effect of nitrogen ion implantation on the axial fatigue strength and wear resistance of 15-5 PH stainless steel. It is well know that electroplated coatings, which are used to improve abrasive wear and corrosion properties, affects negatively the fatigue strength. It is also important to consider requirements to reduce the use of coated materials with electroplated chromium and cadmium, that produce waste, which is harmful to health and environment. The HVOF (High velocity oxygen fuel) process provides hardness, wear strength and higher fatigue resistance in comparison to electroplated chromium. Plasma immersion ion implantation has been used to enhance the hardness, wear, fatigue and corrosion properties of metals and alloys. In the present research the fatigue life increased twice for 15-5 PH three hours PIII treated in comparison to base material. From the abrasive wear tests a lower pin mass reduction was observed, associated to the superficial treatments. The improvement of fatigue and mechanical performance is attributed to a combination of nitrides phase structure and compressive residual stresses during the PIII treatment.

  5. Tribological properties of amorphous alloys and the role of surfaces in abrasive wear of materials

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1982-01-01

    The research approach undertaken by the authors relative to the subject, and examples of results from the authors are reviewed. The studies include programs in adhesion, friction, and various wear mechanisms (adhesive and abrasive wear). The materials which have been studied include such ceramic and metallic materials as silicon carbide, ferrites, diamond, and amorphous alloys.

  6. Metallurgical/Alloy Optimization of High Strength and Wear Resistant Structural Quench and Tempered Steels

    NASA Astrophysics Data System (ADS)

    Stalheim, Douglas G.; Peimao, Fu; Linhao, Gu; Yongqing, Zhang

    Structural steels with yield strength requirements greater or equal to 690 MPa can be produced through controlled recrystallization hot rolling coupled with precipitation strengthening or purposeful heat treatment through quench and tempering (Q&T). High strength structural steel and wear/abrasion resistant requirements greater or equal to 360 Brinell hardness (BHN) are produced by the development of microstructures of tempered lower bainite and/or martensite through the Q&T process. While these Q&T microstructures can produce very high strengths and hardness levels making them ideal for 690 MPa plus yield strength or wear/abrasion resistant applications, they lack toughness/ductility and hence are very brittle and prone to cracking. While tempering the microstructures helps in improving the toughness/ductility and reducing the brittleness, strength and hardness can be sacrificed. In addition, these steels typically consist of alloy designs containing boron with carbon equivalents (CE) greater than 0.50 to achieve the desired microstructures. The higher CE has a negative influence on weldability.

  7. Fissure sealant materials: Wear resistance of flowable composite resins

    PubMed Central

    Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi

    2016-01-01

    Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm2 and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm2of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics. PMID:27651887

  8. Fissure sealant materials: Wear resistance of flowable composite resins.

    PubMed

    Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi

    2016-01-01

    Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm(2) and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm(2)of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

  9. Advanced Wear-resistant Nanocomposites for Increased Energy Efficiency

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cook, B. A.; Harringa, J. L.; Russel, A. M.

    This report summarizes the work performed by an Ames-led project team under a 4-year DOE-ITP sponsored project titled, 'Advanced Wear-resistant Nanocomposites for Increased Energy Efficiency.' The Report serves as the project deliverable for the CPS agreement number 15015. The purpose of this project was to develop and commercialize a family of lightweight, bulk composite materials that are highly resistant to degradation by erosive and abrasive wear. These materials, based on AlMgB{sub 14}, are projected to save over 30 TBtu of energy per year when fully implemented in industrial applications, with the associated environmental benefits of eliminating the burning of 1.5more » M tons/yr of coal and averting the release of 4.2 M tons/yr of CO{sub 2} into the air. This program targeted applications in the mining, drilling, machining, and dry erosion applications as key platforms for initial commercialization, which includes some of the most severe wear conditions in industry. Production-scale manufacturing of this technology has begun through a start-up company, NewTech Ceramics (NTC). This project included providing technical support to NTC in order to facilitate cost-effective mass production of the wear-resistant boride components. Resolution of issues related to processing scale-up, reduction in energy intensity during processing, and improving the quality and performance of the composites, without adding to the cost of processing were among the primary technical focus areas of this program. Compositional refinements were also investigated in order to achieve the maximum wear resistance. In addition, synthesis of large-scale, single-phase AlMgB{sub 14} powder was conducted for use as PVD sputtering targets for nanocoating applications.« less

  10. Characterization of Microstructure and Wear Resistance of PEO Coatings Containing Various Microparticles on Ti6Al4V Alloy

    NASA Astrophysics Data System (ADS)

    Li, Xinyi; Dong, Chaofang; Zhao, Qing; Pang, Yu; Cheng, Fasong; Wang, Shuaixing

    2018-02-01

    Titania-based composite coatings were prepared by plasma electrolytic oxidation (PEO) treatment of Ti6Al4V alloy in electrolyte with α-Al2O3, Cr2O3 or h-BN microparticles in suspension. The microstructure, composition of PEO composite coatings were analyzed by SEM, EDS and XRD. The wear resistance of composite ceramic coatings was studied by ball-on-disk wear test at ambient temperature and 300 °C. The results showed that the addition of microparticles accelerated the growth rate of PEO coating and changed the microstructure and composition of PEO coating. PEO coating was porous and mainly composed of rutile-TiO2, anatase-TiO2 and Al2TiO5. PEO/α-Al2O3 (Cr2O3 or h-BN) composite coating only had small micropores and appeared some α-Al2O3 (Cr2O3 or h-BN) phase. Besides, the addition of α-Al2O3 (Cr2O3 or h-BN) microparticles greatly improved the wear resistance of PEO coating. At ambient temperature, abrasive wear dominated the wear behavior of PEO coating, but abrasive wear and adhesive peel simultaneously happened at 300 °C. Whether at ambient temperature or 300 °C, PEO composite coating had better wear resistance than PEO coating. Besides, PEO/h-BN composite coating outperformed other composite coatings regardless of the temperature.

  11. Study of abrasive wear process of lining of grinding chamber of vortex-acoustic disperser

    NASA Astrophysics Data System (ADS)

    Perelygin, D. N.

    2018-03-01

    The theoretical and experimental studies of the process of gas-abrasive wear of the lining of a vortex-acoustic disperser made it possible to establish the conditions and patterns of their occurrence and also to develop proposals for its reduction.

  12. A new methodology for predictive tool wear

    NASA Astrophysics Data System (ADS)

    Kim, Won-Sik

    turned with various cutting conditions and the results were compared with the proposed analytical wear models. The crater surfaces after machining have been carefully studied to shed light on the physics behind the crater wear. In addition, the abrasive wear mechanism plays a major role in the development of crater wear. Laser shock processing (LSP) has been applied to locally relieve the deleterious tensile residual stresses on the crater surface of a coated tool, thus to improve the hardness of the coating. This thesis shows that LSP has indeed improve wear resistance of CVD coated alumina tool inserts, which has residual stress due to high processing temperature. LSP utilizes a very short laser pulse with high energy density, which induces high-pressure stress wave propagation. The residual stresses are relieved by incident shock waves on the coating surface. Residual stress levels of LSP CVD alumina-coated carbide insert were evaluated by the X-ray diffractometer. Based on these results, LSP parameters such as number of laser pulses and laser energy density can be controlled to reduce residual stress. Crater wear shows that the wear resistance increase with LSP treated tool inserts. Because the hardness data are used to predict the wear, the improvement in hardness and wear resistance shows that the mechanism of crater wear also involves abrasive wear.

  13. Improved Wear Resistance of Low Carbon Steel with Plasma Melt Injection of WC Particles

    NASA Astrophysics Data System (ADS)

    Liu, Aiguo; Guo, Mianhuan; Hu, Hailong

    2010-08-01

    Surface of a low carbon steel Q235 substrate was melted by a plasma torch, and tungsten carbide (WC) particles were injected into the melt pool. WC reinforced surface metal matrix composite (MMC) was synthesized. Dry sliding wear behavior of the surface MMC was studied and compared with the substrate. The results show that dry sliding wear resistance of low carbon steel can be greatly improved by plasma melt injection of WC particles. Hardness of the surface MMC is much higher than that of the substrate. The high hardness lowers the adhesion and abrasion of the surface MMC, and also the friction coefficient of it. The oxides formed in the sliding process also help to lower the friction coefficient. In this way, the dry sliding wear resistance of the surface MMC is greatly improved.

  14. Morphology of powders of tungsten carbide used in wear-resistant coatings and deposition on the PDC drill bits

    NASA Astrophysics Data System (ADS)

    Zakharova, E. S.; Markova, I. Yu; Maslov, A. L.; Polushin, N. I.; Laptev, A. I.

    2017-05-01

    Modern drill bits have high abrasive wear in the area of contact with the rock and removed sludge. Currently, these bits have a protective layer on the bit body, which consists of a metal matrix with inclusions of carbide particles. The research matrix of this coating and the wear-resistant particles is a prerequisite in the design and production of drill bits. In this work, complex investigation was made for various carbide powders of the grades Relit (tungsten carbide produced by Ltd “ROSNAMIS”) which are used as wear-resistant particles in the coating of the drill bit body. The morphology and phase composition of the chosen powders as well as the influence of a particle shape on prospects of their application in wear-resistance coating presented in this work.

  15. Comprehensive study of the abrasive wear and slurry erosion behavior of an expanded system of high chromium cast iron and microstructural modification for enhanced wear resistance

    NASA Astrophysics Data System (ADS)

    Chung, Reinaldo Javier

    High chromium cast irons (HCCIs) have been demonstrated to be an effective material for a wide range of applications in aggressive environments, where resistances to abrasion, erosion and erosion-corrosion are required. For instance, machinery and facilities used in mining and extraction in Alberta's oil sands suffer from erosion and erosion-corrosion caused by silica-containing slurries, which create challenges for the reliability and maintenance of slurry pumping systems as well as other processing and handling equipment. Considerable efforts have been made to determine and understand the relationship between microstructural features of the HCCIs and their wear performance, in order to guide the material selection and development for specific service conditions with optimal performance. The focus was previously put on a narrow group of compositions dictated by ASTM A532. However, with recent advances in casting technology, the HCCI compositional range can be significantly expanded, which potentially brings new alloys that can be superior to those which are currently employed. This work consists of three main aspects of study. The first one is the investigation of an expanded system of white irons with their composition ranging from 1 to 6 wt.% C and 5 to 45 wt.% Cr, covering 53 alloys. This work has generated wear and corrosion maps and established correlation between the performance and microstructural features for the alloys. The work was conducted in collaboration with the Materials Development Center of Weir Minerals in Australia, and the results have been collected in a database that is used by the company to guide materials selection for slurry pump components in Alberta oil sands and in other mining operations throughout the world. The second part consists of three case studies on effects of high chromium and high carbon, respectively, on the performance of the HCCIs. The third aspect is the development of an approach to enhance the wear resistance of

  16. Continuous Monitoring of Pin Tip Wear and Penetration into Rock Surface Using a New Cerchar Abrasivity Testing Device

    NASA Astrophysics Data System (ADS)

    Hamzaban, Mohammad-Taghi; Memarian, Hossein; Rostami, Jamal

    2014-03-01

    Evaluation of rock abrasivity is important when utilizing mechanized excavation in various mining and civil projects in hard rock. This is due to the need for proper selection of the rock cutting tools, estimation of the tool wear, machine downtime for cutter change, and costs. The Cerchar Abrasion Index (CAI) test is one of the simplest and most widely used methods for evaluating rock abrasivity. In this study, a new device for the determination of frictional forces and depth of pin penetration into the rock surface during a Cerchar test is discussed. The measured parameters were used to develop an analytical model for calculation of the size of the wear flat (and hence a continuous measure of CAI as the pin moves over the sample) and pin tip penetration into the rock during the test. Based on this model, continuous curves of CAI changes and pin tip penetration into the rock were plotted. Results of the model were used for introduction of a new parameter describing rock-pin interaction and classification of rock abrasion.

  17. Friction and abrasion of elastomeric materials

    NASA Technical Reports Server (NTRS)

    Gent, A. N.

    1975-01-01

    An abrasion apparatus is described. Experimental measurements are reported for four representative elastomeric materials, including a typical high-quality tire tread material and a possible replacement material for aircraft tire treads based on transpolypentenamer (TPPR). Measurements are carried out at different levels of frictional work input, corresponding to different severities of wear, and at both ambient temperature and at 100 C. Results indicate the marked superiority in abrasion resistance of the material based on TPPR, especially at 100 C, in comparison with the other materials examined.

  18. Abrasion-resistant concrete mix designs for precast bridge deck panels.

    DOT National Transportation Integrated Search

    2010-08-01

    The report documents laboratory investigations undertaken to develop high performance concrete (HPC) for precast and pre-stressed bridge deck components that would reduce the life-cycle cost of bridges by improving the studded tire wear (abrasion) re...

  19. Impact of dentifrice abrasivity and remineralization time on erosive tooth wear in vitro.

    PubMed

    Buedel, Sarah; Lippert, Frank; Zero, Domenick T; Eckert, George J; Hara, Anderson T

    2018-02-01

    To investigate the in vitro effects of simulated dentifrice slurry abrasivity (L-low, M-medium and H-high) and remineralization time (0, 30, 60 and 120 minutes) on erosive tooth wear. Enamel and root dentin specimens were prepared from bovine incisors (n= 8) and submitted to a cycling protocol including erosion, remineralization at the test times, and brushing with each of the tested slurries, for 5 days. Dental surface loss (SL) was determined by optical profilometry. Data was analyzed using mixed-model ANOVA and Fisher's PLSD tests (alpha= 0.05). SL generally increased along with the increase in slurry abrasive level, with significance dependent upon the specific substrate and remineralization times. H showed the highest SL on both enamel and dentin; remineralization for 30 minutes reduced SL significantly (P< 0.05), but only for enamel. M showed intermediate SL values, with remineralization benefit clearly seen only after 120 minutes of remineralization (P< 0.05). L caused the least SL for both enamel and dentin, which was further reduced after remineralization for 120 and 30 minutes, respectively (both P< 0.05). Overall, root dentin had significantly higher SL than enamel. Less abrasive dentifrice slurries were able to reduce toothbrushing abrasion on both enamel and root dentin. This protection was enhanced by remineralization for all abrasive levels on enamel, but only for L on root dentin. High-risk erosion patients should avoid highly abrasive toothpastes, as remineralization can only partially compensate for their deleterious effects on eroded dental surfaces. Lower abrasive toothpastes are recommended. Copyright©American Journal of Dentistry.

  20. High-temperature Friction and Wear Resistance of Ni-Co-SiC Composite Coatings

    NASA Astrophysics Data System (ADS)

    Guo, Fang; Sun, Wan-chang; Jia, Zong-wei; Liu, Xiao-jia; Dong, Ya-ru

    2018-05-01

    Ni-Co alloy and SiC micro-particles were co-deposited on 45 steel by electrodeposition for high temperature performance. The high temperature tribological characteristics were studied by use of a ball-on-disk method. The micrographs and phase structure of the Ni-Co-SiC composite coatings after high-temperature friction were observed by using a field emission scanning electron microscope(FESEM). The results reveal that the Ni-Co-SiC composite coating presents better wear resistance and lower friction coefficient at high temperature in comparison with that of Ni-Co coating and 45 steel substrate. The embedded SiC particles could strengthen the alloy coating by dispersion strengthening effect and changing the friction mechanism from adhesive wear to abrasive wear.

  1. Relationships Between Abrasive Wear, Hardness, and Surface Grinding Characteristics of Titanium-Based Metal Matrix Composites

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Blau, Peter Julian; Jolly, Brian C

    2009-01-01

    The objective of this work was to support the development of grinding models for titanium metal-matrix composites (MMCs) by investigating possible relationships between their indentation hardness, low-stress belt abrasion, high-stress belt abrasion, and the surface grinding characteristics. Three Ti-based particulate composites were tested and compared with the popular titanium alloy Ti-6Al-4V. The three composites were a Ti-6Al-4V-based MMC with 5% TiB{sub 2} particles, a Ti-6Al-4V MMC with 10% TiC particles, and a Ti-6Al-4V/Ti-7.5%W binary alloy matrix that contained 7.5% TiC particles. Two types of belt abrasion tests were used: (a) a modified ASTM G164 low-stress loop abrasion test, and (b)more » a higher-stress test developed to quantify the grindability of ceramics. Results were correlated with G-ratios (ratio of stock removed to abrasives consumed) obtained from an instrumented surface grinder. Brinell hardness correlated better with abrasion characteristics than microindentation or scratch hardness. Wear volumes from low-stress and high-stress abrasive belt tests were related by a second-degree polynomial. Grindability numbers correlated with hard particle content but were also matrix-dependent.« less

  2. Wear mechanisms and improvements of wear resistance in cobalt-chromium alloy femoral components in artificial total knee joints

    NASA Astrophysics Data System (ADS)

    Que, Like

    CrMo alloy surface roughness was higher than 0.022 mum Ra (surface roughness average), UHMWPE wear increased with increasing CoCrMo alloy surface roughness. Bone and poly(methyl methacrylate) (PMMA) bone cement abrasive particles created scratches on the alloy via a ploughing mechanism, and resulted in significantly rougher surfaces than controls without particles (P < 0.01). Solution treatments at 1230sp°C and 1245sp°C reduced the hardness and wear resistance of the as-cast F75 CoCrMo alloy. Aging at 700sp°C caused recrystallization of the forged F799 alloy and improved wear resistance. Thermo-mechanical treatments have the potential to increase the lifetime of artificial joints by increasing the wear resistance of CoCrMo components.

  3. The effect of fiber treatment on abrasive wear properties of palm fiber reinforced epoxy composite

    NASA Astrophysics Data System (ADS)

    Razak, Muhammad Firdaus Abdul; Bakar, Mimi Azlina Abu; Kasolang, Salmiah; Ahmad, Mohamad Ali

    2017-12-01

    Oil palm industries generate at least 30 million tons of lignocellulosic biomass annually in the form of oil palm trunks (OPT), empty fruit bunches (EFB), oil palm fronds (OPF) and palm pressed fibres (PPF). The palm fiber is one of the natural fibers used as reinforcement in composite materials in order to decrease environmental issues and promotes utilization of renewable resources. This paper presents a study on the effect of alkaline treatment on wear properties of palm fiber reinforced epoxy resin composite. Abrasive wear testing was deployed to investigate the wear profile of the composite surfaces. Testing was carried out which focused on the effect of alkaline treatment to the palm fiber under different amounts of fiber loading i.e. 1 wt%, 3 wt%, 5 wt% and 7 wt%. The palm fibers were soaked into 6 % of alkaline solution or natrium hydroxide (NaOH) for 12 hours. The fiber was treated in order to remove amorphous materials such as hemicelluloses, lignins and pectins of the fiber. The wear test samples were fabricated using hand lay-up technique and cured at room temperature for 24 hours. Surface roughness of the composite material was also measured using the surface measuring instrument. Dry sliding wear test was performed at room temperature at a constant velocity of 1.4 m/s with a constant load of 10 N by using the Abrasion Test Machine. Result shows that 5 wt% and 7 wt% treated palm fiber loadings have better specific wear rate compared to lower fiber loadings. The finding of this study contributes towards material development and utilization in promoting `waste into wealth' which is in line with national aspiration.

  4. The Wear Behavior of HVOF Sprayed Near-Nanostructured WC-17%Ni(80/20)Cr Coatings in Dry and Slurry Wear Conditions

    NASA Astrophysics Data System (ADS)

    Ben Mahmud, Tarek A.; Atieh, Anas M.; Khan, Tahir I.

    2017-07-01

    The ability to deposit nanostructured feedstock by using high-velocity oxygen-fuel (HVOF) spray offers potential improvements in coating hardness, wear resistance and toughness for applications in the oil sands industry. In this study, the wear behavior of a near-nanostructured coating was compared under dry and slurry abrasive wear test using an uncoated AISI-1018 low-carbon steel substrate as a reference. The coating microstructures were analyzed in the as-sprayed, dry and slurry test conditions using scanning electron microscopy, x-ray diffraction and microhardness measurements. Wear behavior of the steel and coating surfaces were assessed using a pin-on-plate wear test under various loads. The results showed that a coating could be successfully deposited using the HVOF spraying technique and with retention of the near-nanosized WC dispersion within the coating structure. The wear rate under dry test conditions was greater for the steel and coating compared to tests performed under slurry conditions. Examination of the wear tracks revealed that the wear mechanism was different for the two test conditions. Wear in the dry test condition resulted from 2-body abrasion, while 3-body abrasion dominated wear in slurry conditions. The latter showed lower wear rates due to a lubricating effect of the oil.

  5. Study of abrasive wear rate of silicon using n-alcohols

    NASA Technical Reports Server (NTRS)

    Danyluk, S.

    1982-01-01

    The work carried out at the University of Illinois at Chicago for the Flat-Plate Solar Array Project under contract No. 956053 is summarized. The abrasion wear rate of silicon in a number of fluid environments and the parameters that influence the surface mechanical properties of silicon were determined. Three tests were carried out in this study: circular and linear multiple-scratch test, microhardness test and a three-point bend test. The pertinent parameters such as effect of surface orientation, dopant and fluid properties were sorted. A brief review and critique of previous work is presented.

  6. Wear and microhardness of different resin composite materials.

    PubMed

    Say, Esra Can; Civelek, Arzu; Nobecourt, Alain; Ersoy, Mustafa; Guleryuz, Canan

    2003-01-01

    This study determined the three-body abrasive wear resistance of two packable composites (P-60; Solitaire 2), an ion-releasing composite (Ariston AT), a hybrid composite (Tetric Ceram) and an ormocer (Admira). The study also looked at the correlation between wear resistance and hardness of the composites. Three-body wear testing was performed using an ACTA wear machine with 15 N contact force using millet seed as the third body. Wear depth (microm) was measured by profilometry after 200,000 cycles. The hardness test was performed using a digital microhardness tester (load: 500 g; dwell time: 15 seconds). The data were analyzed by using Kruskal Wallis (p < 0.05). There were statistically significant differences among the three body abrasive wear of the composites. The ranking from least to most were as follows: Filtek P-60 < Solitaire 2 < Ariston AT < Tetric Ceram < Admira. Filtek P-60 showed the highest microhardness value. No other significant differences in hardness were observed among the different resin composites (P-60 > AristonAT = Tetric Ceram = Solitaire 2 = Admira). The results of this study indicate that there are significant differences in the wear resistance of the resin composites. The correlation between hardness and wear was significant with a correlation coefficient of r:-0.91. A significant negative correlation exists between hardness and three-body wear of resin composites.

  7. Study of Two-Body Wear Performance of Dental Materials.

    PubMed

    Hu, Xin; Zhang, Qian; Ning, Jia; Wu, Wenmeng; Li, Changyi

    2018-06-01

    The purpose of this study was to evaluate the two-body wear resistances of natural enamel and four dental materials in vitro. The testing machine was modified to form a type of pin-on-disk wear test apparatus. Four dental material specimens (Au-Pd alloy, Ag-Pd alloy, FiltekTMP60 and FiltekTMZ350 composite resins) and enamel were used as the pins, and a steatite ceramic grinding wheel was used as the abrasive counter face. The wear volume loss and the rigidity value was measured. The worn surface and the element analysis of the debris were analyzed. The wear volume loss of Au-Pd alloy and its steatite antagonists were the nearest to those of the dental enamel. SEM microphotographs showed that, the main wear mechanism of the dental materials was abrasive and adhesive wear. Au-Pd alloy had good wear resistance and was more suitable for dental applications than other three dental materials. Copyright © 2017 National Medical Association. Published by Elsevier Inc. All rights reserved.

  8. Abrasive wear response of TIG-melted TiC composite coating: Taguchi approach

    NASA Astrophysics Data System (ADS)

    Maleque, M. A.; Bello, K. A.; Adebisi, A. A.; Dube, A.

    2017-03-01

    In this study, Taguchi design of experiment approach has been applied to assess wear behaviour of TiC composite coatings deposited on AISI 4340 steel substrates by novel powder preplacement and TIG torch melting processes. To study the abrasive wear behaviour of these coatings against alumina ball at 600° C, a Taguchi’s orthogonal array is used to acquire the wear test data for determining optimal parameters that lead to the minimization of wear rate. Composite coatings are developed based on Taguchi’s L-16 orthogonal array experiment with three process parameters (welding current, welding speed, welding voltage and shielding gas flow rate) at four levels. In this technique, mean response and signal-to-noise ratio are used to evaluate the influence of the TIG process parameters on the wear rate performance of the composite coated surfaces. The results reveal that welding voltage is the most significant control parameter for minimizing wear rate while the current presents the least contribution to the wear rate reduction. The study also shows the best optimal condition has been arrived at A3 (90 A), B4 (2.5 mm/s), C3 (30 V) and D3 (20 L/min), which gives minimum wear rate in TiC embedded coatings. Finally, a confirmatory experiment has been conducted to verify the optimized result and shows that the error between the predicted values and the experimental observation at the optimal condition lies within the limit of 4.7 %. Thus, the validity of the optimum condition for the coatings is established.

  9. Influence of deep cryogenic treatment on structure and wear resistance of materials of hydraulic breaker chisels

    NASA Astrophysics Data System (ADS)

    Bolobov, V. I.; BinhLe, Thanh

    2018-03-01

    It is shown that shallow cryogenic treatment at -75°C (SCT) of the materials of hydraulic breaker chisels - P20, 1080 and D2 steels leads to a decrease (44 ÷ 82%) in the amount of retained austenite and an increase (26 ÷ 99%) in the amount of carbides in the structure of hardened steel, which is accompanied by an increase in its hardness (1.4 ÷ 2.1%) and abrasive wear resistance (10 ÷ 31%) with a simultaneous decrease in impact toughness (19 ÷ 24%). Deep cryogenic treatment at -196°C (DCT) and subsequent low-temperature tempering of D2 steel leads to a significant increase in its wear resistance (98%) and impact toughness (32%).

  10. Investigations of Novel Surface Modification Techniques for Wear Resistant Al and Mg Based Materials

    DTIC Science & Technology

    1994-01-01

    microhardness to resist the abrasive wear. Moreover it is required to form dense or fine-porous uniform layers to provide the antifriction characteristics...technological regimes for production of OCC having maximum of thickness, microhardness and uniformity is expediently to carry on using the silicate-alkali...includes at the same time both the index of the process effectiveness and the strength and geometrical characteristics of the product . In connection

  11. Wear and corrosion resistance of laser-cladded Fe-based composite coatings on AISI 4130 steel

    NASA Astrophysics Data System (ADS)

    Fan, Li; Chen, Hai-yan; Dong, Yao-hua; Dong, Li-hua; Yin, Yan-sheng

    2018-06-01

    The wear and corrosion resistance of Fe72.2Cr16.8Ni7.3Mo1.6Mn0.7C0.2Si1.2 and Fe77.3Cr15.8Ni3.9Mo1.1Mn0.5C0.2Si1.2 coatings laser-cladded on AISI 4130 steel were studied. The coatings possess excellent wear and corrosion resistance despite the absence of expensive yttrium, tungsten, and cobalt and very little molybdenum. The microstructure mainly consists of dendrites and eutectic phases, such as duplex (γ+α)-Fe and the Fe-Cr (Ni) solid solution, confirmed via energy dispersive spectrometry and X-ray diffraction. The cladded Fe-based coatings have lower coefficients of friction, and narrower and shallower wear tracks than the substrate without the cladding, and the main wear mechanism is mild abrasive wear. Electrochemical test results suggest that the soft Fe72.2Cr16.8Ni7.3Mo1.6Mn0.7C0.2Si1.2 coating with high Cr and Ni concentrations has high passivation resistance, low corrosion current, and positive corrosion potential, providing a better protective barrier layer to the AISI 4130 steel against corrosion.

  12. Effect of power toothbrushing on simulated wear of dental cement margins.

    PubMed

    Black, Marsha A; Bayne, Stephen C; Peterson, Charlotte A

    2007-01-01

    Power toothbrushes (PTBs), in combination with abrasive dentifrices, may encourage wear of dental cements at crown margins. The objective of this in vitro simulation was to control the clinical variables associated with PTB use and measure the potential side effects of PTBs with mild and abrasive dentifrices. Four PTBs ( Braun-Oral-B-Professional Care at 150 g brushing force, Sonicare-Elite at 90 g, Colgate-Actibrush at 200 g and Crest-Spinbrush-Pro at 250 g) and 2 dentifrices mixed 1:1 with tap water (Mild= Colgate-Total, Colgate-Palmolive; Abrasive= Close-up, Chesebrough-Ponds) versus tap water alone (control) were used to abrade 2 cements (Fleck's Mizzy Zinc Phosphate [ZP]; 3M-ESPE Unicem universal cement [UC]) using cement-filled slots (160 m wide) cut into wear-resistant ceramic blocks. A custom fixture controlled PTB/block alignment, PTB loads, and other testing variables. Wear was measured (3 profilometer traces/slot, 5 slots/block/group, baseline to 5-year differences) and analyzed (3-way ANOVA, p < or = 0.05, Bonferroni). Wear for ZP was much greater than UC (p<0.05) for all 4 PTBs and both dentifrices. Brushing with water showed no effects (p<0.05). Cement-PTB-dentifrice interactions did occur. Only minor differences occurred among PTBs. Pooled 5y-wear levels for ZP for both dentifrices approximately 21 microm /5y) were similar to values for current-day posterior composite materials. Combinations of PTBs with mild and abrasive dentifrices produced significant wear with ZP but not UC; thus, resin-composite cements seem to represent a better choice for wear resistance.

  13. Optical tools for high-throughput screening of abrasion resistance of combinatorial libraries of organic coatings

    NASA Astrophysics Data System (ADS)

    Potyrailo, Radislav A.; Chisholm, Bret J.; Olson, Daniel R.; Brennan, Michael J.; Molaison, Chris A.

    2002-02-01

    Design, validation, and implementation of an optical spectroscopic system for high-throughput analysis of combinatorially developed protective organic coatings are reported. Our approach replaces labor-intensive coating evaluation steps with an automated system that rapidly analyzes 8x6 arrays of coating elements that are deposited on a plastic substrate. Each coating element of the library is 10 mm in diameter and 2 to 5 micrometers thick. Performance of coatings is evaluated with respect to their resistance to wear abrasion because this parameter is one of the primary considerations in end-use applications. Upon testing, the organic coatings undergo changes that are impossible to quantitatively predict using existing knowledge. Coatings are abraded using industry-accepted abrasion test methods at single-or multiple-abrasion conditions, followed by high- throughput analysis of abrasion-induced light scatter. The developed automated system is optimized for the analysis of diffusively scattered light that corresponds to 0 to 30% haze. System precision of 0.1 to 2.5% relative standard deviation provides capability for the reliable ranking of coatings performance. While the system was implemented for high-throughput screening of combinatorially developed organic protective coatings for automotive applications, it can be applied to a variety of other applications where materials ranking can be achieved using optical spectroscopic tools.

  14. Wear Resistance Increase by Friction Stir Processing for Partial Magnesium Replacement in Aluminium Alloys

    NASA Astrophysics Data System (ADS)

    Balos, Sebastian; Labus Zlatanovic, Danka; Janjatovic, Petar; Dramicanin, Miroslav; Rajnovic, Dragan; Sidjanin, Leposava

    2018-03-01

    In this paper, the influence of friction stir processing (FSP) was evaluated as a way of increasing mechanical properties and a way of replacing the magnesium content in aluminium alloys. FSP was done on AA5754 H111 aluminium alloy, containing 3 % Mg, by using various types of tools and different welding speeds, rotational speeds and tilt angles. Wear test was done against SiC abrasive papers. SiC was used to simulate extreme abrasive wear conditions. The wear test was done on untreated AA5754 specimens, processed AA5754 specimens and untreated AA5083 H111 specimens, the latter containing 4.5 % Mg. AA5083 was chosen as an alternative to AA5754, but with a significantly higher Mg content. Base material microhardness was 60 HV1 and 80 HV1 for AA5754 and AA5083 alloys respectively. To find the effect of FSP on AA5754 alloy, microstructures were studied, mainly grain size in the stir zone. It was found, that an elevated processing and rotational speed, without tilt angle and the tool without a reservoir resulted in an increase in hardness of the AA5754 to 70 HV1, but with the occurrence of tunneling defect and the wear rate of 79.3 mg. Lower FSP parameters and a tilted tool with a reservoir resulted in microhardness of 68 HV1 and wear rate of 68.2 mg without tunneling. These wear values are lower than those obtained with unmodified Al-alloys: AA5754 97.2 mg and AA5083 86.3 mg. An increased wear resistance can be attributed to the combined effect of grain boundary strengthening mechanism and solid solution strengthening, versus only the latter in untreated alloys.

  15. Solid Lubrication Fundamentals and Applications. Chapter 5; Abrasion: Plowing and Cutting

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2001-01-01

    Chapter 5 discusses abrasion, a common wear phenomenon of great economic importance. It has been estimated that 50% of the wear encountered in industry is due to abrasion. Also, it is the mechanism involved in the finishing of many surfaces. Experiments are described to help in understanding the complex abrasion process and in predicting friction and wear behavior in plowing and/or cutting. These experimental modelings and measurements used a single spherical pin (asperity) and a single wedge pin (asperity). Other two-body and three-body abrasion studies used hard abrasive particles.

  16. Abrasion resistant heat pipe

    DOEpatents

    Ernst, D.M.

    1984-10-23

    A specially constructed heat pipe is described for use in fluidized bed combustors. Two distinct coatings are spray coated onto a heat pipe casing constructed of low thermal expansion metal, each coating serving a different purpose. The first coating forms aluminum oxide to prevent hydrogen permeation into the heat pipe casing, and the second coating contains stabilized zirconium oxide to provide abrasion resistance while not substantially affecting the heat transfer characteristics of the system.

  17. A comparison of the wear resistance and hardness of indirect composite resins.

    PubMed

    Mandikos, M N; McGivney, G P; Davis, E; Bush, P J; Carter, J M

    2001-04-01

    Various new, second-generation indirect composites have been developed with claimed advantages over existing tooth-colored restorative materials. To date, little independent research has been published on these materials, and the properties specified in the advertising materials are largely derived from in-house or contracted testing. Four second-generation indirect composites (Artglass, belleGlass, Sculpture, and Targis) were tested for wear resistance and hardness against 2 control materials with well-documented clinical application. Human enamel was also tested for comparison. Twelve specimens of each material were fabricated according to the manufacturers' directions and subjected to accelerated wear in a 3-body abrasion, toothbrushing apparatus. Vickers hardness was measured for each of the tested materials, and energy dispersive x-ray (EDX) spectroscopy was performed to determine the elemental composition of the composite fillers. The statistical tests used for wear and hardness were the Kruskal-Wallis 1-way ANOVA test with Mann-Whitney tests and 1-way ANOVA with multiple comparisons (Tukey HSD). The Pearson correlation coefficient was used to determine the existence of a relationship between the hardness of the materials and the degree to which they had worn. The level of statistical significance chosen was alpha=.05. The control material Concept was superior to the other composites in wear resistance and hardness and had the lowest surface roughness. Significant relationships were observed between depth of wear and hardness and between depth of wear and average surface roughness. Enamel specimens were harder and more wear resistant than any of the composites. EDX spectroscopy revealed that the elemental composition of the fillers of the 4 new composites was almost identical, as was the composition of the 2 control composites. The differences in wear, hardness, and average surface roughness may have been due to differences in the chemistry or method of

  18. New Rock Abrasivity Test Method for Tool Life Assessments on Hard Rock Tunnel Boring: The Rolling Indentation Abrasion Test (RIAT)

    NASA Astrophysics Data System (ADS)

    Macias, F. J.; Dahl, F.; Bruland, A.

    2016-05-01

    The tunnel boring machine (TBM) method has become widely used and is currently an important presence within the tunnelling industry. Large investments and high geological risk are involved using TBMs, and disc cutter consumption has a great influence on performance and cost, especially in hard rock conditions. Furthermore, reliable cutter life assessments facilitate the control of risk as well as avoiding delays and budget overruns. Since abrasive wear is the most common process affecting cutter consumption, good laboratory tests for rock abrasivity assessments are needed. A new abrasivity test method by rolling disc named Rolling Indentation Abrasion Test (RIAT) has been developed. The goal of the new test design and procedure is to reproduce wear behaviour on hard rock tunnel boring in a more realistic way than the traditionally used methods. Wear by rolling contact on intact rock samples is introduced and several rock types, covering a wide rock abrasiveness range, have been tested by RIAT. The RIAT procedure indicates a great ability of the testing method to assess abrasive wear on rolling discs. In addition and to evaluate the newly developed RIAT test method, a comprehensive laboratory testing programme including the most commonly used abrasivity test methods and the mineral composition were carried out. Relationships between the achieved results from conventional testing and RIAT results have been analysed.

  19. Study on biocompatibility, tribological property and wear debris characterization of ultra-low-wear polyethylene as artificial joint materials.

    PubMed

    Bian, Yan-Yan; Zhou, Lei; Zhou, Gang; Jin, Zhong-Min; Xin, Shi-Xuan; Hua, Zi-Kai; Weng, Xi-Sheng

    2018-06-01

    Ultra-low-wear polyethylene (ULWPE) is a new type polyethylene made by experts who are from China petrochemical research institute, which is easy to process and implant. Preliminary test showed it was more resistant to wear than that of Ultra-high-molecular weight polyethylene (UHMWPE). The purpose of the research is to study biocompatibility, bio-tribological properties and debris characterization of ULWPE. Cytotoxicity test, hemolysis test, acute/chronic toxicity and muscular implantation test were conducted according to national standard GB/T-16886/ISO-10993 for evaluation requirements of medical surgical implants. We obtained that this novel material had good biocompatibility and biological safety. The wear performance of ULWPE and UHMWPE was evaluated in a pin-on-disc (POD) wear tester within two million cycles and a knee wear simulator within six million cycles. We found that the ULWPE was higher abrasion resistance than the UHMWPE, the wear rate of ULWPE by POD test and knee wear simulator was 0.4 mg/10 6 cycles and (16.9 ± 1.8)mg/10 6 cycles respectively, while that of UHMWPE was 1.8 mg/10 6 cycles and (24.6 ± 2.4)mg/10 6 cycles. The morphology of wear debris is also an important factor to evaluate artificial joint materials, this study showed that the ULWPE wear debris gotten from the simulator had various different shapes, including spherical, block, tear, etc. The morphology of worn surface and wear debris analysis showed that wear mechanisms of ULWPE were adhesion wear, abrasive wear and fatigue wear and other wear forms, which were consistent with that of UHMWPE. Thus we conclude that ULWPE is expected to be a lifetime implantation of artificial joint. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. The effect of aluminum on the work hardening and wear resistance of hadfield manganese steel

    NASA Astrophysics Data System (ADS)

    Zuidema, B. K.; Subramanyam, D. K.; Leslie, W. C.

    1987-09-01

    A study has been made of the work-hardening and wear resistance of aluminum-modified Hadfield manganese steels ranging in composition from 1.00 to 1.75 Pct carbon and from 0.0 to 4.0 Pct aluminum. Aluminum additions reduced carbon activity and diffusivity in austenites of Hadfield’s composition, increasing the metastable solubility of carbon in Hadfield steel. Aluminum additions inhibited mechanical twinning and, by inference, increased the stacking fault energy of austenite. Increasing carbon in solution in austenite expanded the temperature range over which dynamic strain aging and rapid work hardening occurred. Simultaneous aluminum additions and increased carbon content increased the work-hardening rate and high-stress abrasion resistance of Hadfield steel, but there was an optimum aluminum content beyond which both declined. Maximum work-hardening rate was exhibited by an alloy containing nominally 1.75 Pct C, 13.5 Pct Mn, and 1.3 Pct Al. Improved high-stress abrasion resistance was also found in an alloy containing nominally 1.00 Pct C, 13.5 Pct Mn, and 4.0 Pct Al.

  1. Evaluation of composite wear with a new multi-mode oral wear simulator.

    PubMed

    Condon, J R; Ferracane, J L

    1996-07-01

    The goals of this study were to develop a machine which simultaneously produces wear through the two main oral wear mechanisms of abrasion and attrition by the action of an enamel antagonist and to compare the results obtained for dental composites using this machine to those obtained from clinical studies and other in vitro studies. The accuracy of this new wear tester was determined by examining 11 commercial composite filling materials and 1 amalgam. Specimens were subjected to three-body abrasion and attrition wear for 50,000 cycles. Profilometry was used to quantitate wear of the composites. Linear regression analysis was used to correlate the results to those obtained from clinical studies, as well as from other in vitro wear testers. The area of enamel wear was also determined by image analysis. The SEM was used to evaluate the wear surfaces. The lowest abrasion wear was recorded for the amalgam and for the microfill and smaller-particle composites. Attrition wear was enhanced for the microfill composites and one small-particle hybrid. There was a strong correlation between the results obtained with the new wear tester and those obtained in the clinical trials cited in the literature. Wear of the enamel antagonist was the greatest for the composites with the largest particle sizes. The wear tester showed a reasonable correlation with other wear-producing machines. A new wear tester developed to evaluate and discriminate abrasion and attrition wear provided results similar to those reported in the literature for a variety of commercial composites. The new machine is capable of characterizing the behavior of a material in multiple wear modes simultaneously with one simple, realistic test.

  2. Wear Behavior and Microstructure of Mg-Sn Alloy Processed by Equal Channel Angular Extrusion

    PubMed Central

    Chen, Jung-Hsuan; Shen, Yen-Chen; Chao, Chuen-Guang; Liu, Tzeng-Feng

    2017-01-01

    Mg-5wt.% Sn alloy is often used in portable electronic devices and automobiles. In this study, mechanical properties of Mg-5wt.% Sn alloy processed by Equal Channel Angular Extrusion (ECAE) were characterized. More precisely, its hardness and wear behavior were measured using Vickers hardness test and a pin-on-disc wear test. The microstructures of ECAE-processed Mg-Sn alloys were investigated by scanning electron microscope and X-ray diffraction. ECAE process refined the grain sizes of the Mg-Sn alloy from 117.6 μm (as-cast) to 88.0 μm (one pass), 49.5 μm (two passes) and 24.4 μm (four passes), respectively. Meanwhile, the hardness of the alloy improved significantly. The maximum wear resistance achieved in the present work was around 73.77 m/mm3, which was obtained from the Mg-Sn alloy treated with a one-pass ECAE process with a grain size of 88.0 μm. The wear resistance improvement was caused by the grain size refinement and the precipitate of the second phase, Mg2Sn against the oxidation of the processed alloy. The as-cast Mg-Sn alloy with the larger grain size, i.e., 117.6 μm, underwent wear mechanisms, mainly adhesive wear and abrasive wear. In ECAE-processed Mg-Sn alloy, high internal energy occurred due to the high dislocation density and the stress field produced by the plastic deformation, which led to an increased oxidation rate of the processed alloy during sliding. Therefore, the oxidative wear and a three-body abrasive wear in which the oxide debris acted as the three-body abrasive components became the dominant factors in the wear behavior, and as a result, reduced the wear resistance in the multi-pass ECAE-processed alloy. PMID:29144414

  3. Evaluation of abrasion resistance of pipe and pipe lining materials.

    DOT National Transportation Integrated Search

    2007-09-01

    This project summarizes an evaluation of pipe material resistance to abrasion over a 5-year period (2001-2006) at a site known to be abrasive. : The key focus of the project was to gather more information to compare against existing guidance to desig...

  4. Abrasion resistant composition

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fischer, Keith D; Barnes, Christopher A; Henderson, Stephen L

    A surface covering composition of abrasion resistant character adapted for disposition in overlying bonded relation to a metal substrate. The surface covering composition includes metal carbide particles within a metal matrix at a packing factor of not less than about 0.6. Not less than about 40 percent by weight of the metal carbide particles are characterized by an effective diameter in the range of +14-32 mesh prior to introduction to the metal matrix. Not less than about 3 percent by weight of the metal carbide particles are characterized by an effective diameter of +60 mesh prior to introduction to themore » metal matrix.« less

  5. Aliasing Signal Separation of Superimposed Abrasive Debris Based on Degenerate Unmixing Estimation Technique.

    PubMed

    Li, Tongyang; Wang, Shaoping; Zio, Enrico; Shi, Jian; Hong, Wei

    2018-03-15

    Leakage is the most important failure mode in aircraft hydraulic systems caused by wear and tear between friction pairs of components. The accurate detection of abrasive debris can reveal the wear condition and predict a system's lifespan. The radial magnetic field (RMF)-based debris detection method provides an online solution for monitoring the wear condition intuitively, which potentially enables a more accurate diagnosis and prognosis on the aviation hydraulic system's ongoing failures. To address the serious mixing of pipe abrasive debris, this paper focuses on the superimposed abrasive debris separation of an RMF abrasive sensor based on the degenerate unmixing estimation technique. Through accurately separating and calculating the morphology and amount of the abrasive debris, the RMF-based abrasive sensor can provide the system with wear trend and sizes estimation of the wear particles. A well-designed experiment was conducted and the result shows that the proposed method can effectively separate the mixed debris and give an accurate count of the debris based on RMF abrasive sensor detection.

  6. Aliasing Signal Separation of Superimposed Abrasive Debris Based on Degenerate Unmixing Estimation Technique

    PubMed Central

    Li, Tongyang; Wang, Shaoping; Zio, Enrico; Shi, Jian; Hong, Wei

    2018-01-01

    Leakage is the most important failure mode in aircraft hydraulic systems caused by wear and tear between friction pairs of components. The accurate detection of abrasive debris can reveal the wear condition and predict a system’s lifespan. The radial magnetic field (RMF)-based debris detection method provides an online solution for monitoring the wear condition intuitively, which potentially enables a more accurate diagnosis and prognosis on the aviation hydraulic system’s ongoing failures. To address the serious mixing of pipe abrasive debris, this paper focuses on the superimposed abrasive debris separation of an RMF abrasive sensor based on the degenerate unmixing estimation technique. Through accurately separating and calculating the morphology and amount of the abrasive debris, the RMF-based abrasive sensor can provide the system with wear trend and sizes estimation of the wear particles. A well-designed experiment was conducted and the result shows that the proposed method can effectively separate the mixed debris and give an accurate count of the debris based on RMF abrasive sensor detection. PMID:29543733

  7. c-axis preferential orientation of hydroxyapatite accounts for the high wear resistance of the teeth of black carp (Mylopharyngodon piceus)

    PubMed Central

    Fu, Jimin; He, Chong; Xia, Biao; Li, Yan; Feng, Qiong; Yin, Qifang; Shi, Xinghua; Feng, Xue; Wang, Hongtao; Yao, Haimin

    2016-01-01

    Biological armors such as mollusk shells have long been recognized and studied for their values in inspiring novel designs of engineering materials with higher toughness and strength. However, no material is invincible and biological armors also have their rivals. In this paper, our attention is focused on the teeth of black carp (Mylopharyngodon piceus) which is a predator of shelled mollusks like snails and mussels. Nanoscratching test on the enameloid, the outermost layer of the teeth, indicates that the natural occlusal surface (OS) has much higher wear resistance compared to the other sections. Subsequent X-ray diffraction analysis reveals that the hydroxyapatite (HAp) crystallites in the vicinity of OS possess c-axis preferential orientation. The superior wear resistance of black carp teeth is attributed to the c-axis preferential orientation of HAp near the OS since the (001) surface of HAp crystal, which is perpendicular to the c-axis, exhibits much better wear resistance compared to the other surfaces as demonstrated by the molecular dynamics simulation. Our results not only shed light on the origin of the good wear resistance exhibited by the black carp teeth but are of great value to the design of engineering materials with better abrasion resistance. PMID:27001150

  8. Quantitative image analysis for evaluating the abrasion resistance of nanoporous silica films on glass

    PubMed Central

    Nielsen, Karsten H.; Karlsson, Stefan; Limbach, Rene; Wondraczek, Lothar

    2015-01-01

    The abrasion resistance of coated glass surfaces is an important parameter for judging lifetime performance, but practical testing procedures remain overly simplistic and do often not allow for direct conclusions on real-world degradation. Here, we combine quantitative two-dimensional image analysis and mechanical abrasion into a facile tool for probing the abrasion resistance of anti-reflective (AR) coatings. We determine variations in the average coated area, during and after controlled abrasion. Through comparison with other experimental techniques, we show that this method provides a practical, rapid and versatile tool for the evaluation of the abrasion resistance of sol-gel-derived thin films on glass. The method yields informative data, which correlates with measurements of diffuse reflectance and is further supported by qualitative investigations through scanning electron microscopy. In particular, the method directly addresses degradation of coating performance, i.e., the gradual areal loss of antireflective functionality. As an exemplary subject, we studied the abrasion resistance of state-of-the-art nanoporous SiO2 thin films which were derived from 5–6 wt% aqueous solutions of potassium silicates, or from colloidal suspensions of SiO2 nanoparticles. It is shown how abrasion resistance is governed by coating density and film adhesion, defining the trade-off between optimal AR performance and acceptable mechanical performance. PMID:26656260

  9. Protective Effect of Adhesive Systems associated with Neodymium-doped Yttrium Aluminum Garnet Laser on Enamel Erosive/Abrasive Wear.

    PubMed

    Crastechini, Erica; Borges, Alessandra B; Becker, Klaus; Attin, Thomas; Torres, Carlos Rg

    2017-10-01

    This study evaluated the efficacy of self-etching adhesive systems associated or not associated with the neodymium-doped yttrium aluminum garnet (Nd:YAG) laser on the protection against enamel erosive/abrasive wear. Bovine enamel specimens were demineralized with 0.3% citric acid (5 minutes). The samples were randomly assigned to eight groups (n = 20): SB - Single Bond Universal (3M/ESPE); SB+L - Single Bond Universal + laser (80 mJ/10 Hz); FB - Futurabond U (Voco); FB+L -Futurabond U + laser; GEN - G-aenial bond (GC); GEN+L -G-aenial bond + laser; L - laser irradiation; and C - no treatment. The laser was applied before light curing. The samples were subjected to erosive/abrasive challenges (0.3% citric acid - 2 minutes and tooth brushing four times daily for 5 days). Enamel surface loss was recovered profilometrically by comparison of baseline and final profiles. The adhesive layer thickness, retention percentage of the protective layer, and microhardness of cured adhesive were measured. Data were analyzed using one-way analysis of variance and Tukey's test (5%). There were significant differences for all parameters (p = 0.0001). Mean values ± SD and results of the Tukey's test were: Surface wear: GEN - 4.88 (±1.09)a, L - 5.04 ± 0.99)a, FB - 5.32 (±0.93)ab, GEN + L - 5.46 (±1.27)abc, SB + L - 5.78 (±1.12)abc, FB + L - 6.23 (±1.25)bc, SB - 6.35 (±1.11)c, and C - 6.46 (±0.61)c; layer thickness: GEN - 15.2 (±8.63)c, FB - 5.06 (±1.96)a, GEN + L - 13.96 (±7.07)bc, SB + L - 4.24 (±2.68)a, FB + L - 9.03 (±13.02)abc, and SB - 7.49 (±2.80)ab; retention: GEN - 68.89 (±20.62)c, FB - 54.53 (±24.80)abc, GEN + L - 59.90 (±19.79)abc, SB + L - 63.37 (±19.30)bc, FB + L - 42.23 (±17.68) a, and SB - 47.78 (±18.29)ab; microhardness: GEN - 9.27 (±1.75)c; FB - 6.99 (±0.89)b; GEN + L - 6.22 (±0.87)ab; SB + L - 15.48 (±2.51)d; FB + L - 10.67 (±1.58)c; SB - 5.00 (±1.60)a. The application of Futurabond U and G-aenial bond on enamel surface, as well as the Nd

  10. Assessment of variations in wear test methodology.

    PubMed

    Gouvêa, Cresus V D; Weig, Karin; Filho, Thales R M; Barros, Renata N

    2010-01-01

    The properties of composite resin for dental fillings were improved by development, but its weakness continues to be its wear strength. Several tests have been proposed to evaluate wear in composite resin materials. The aim of this study was to verify how polishing and the type of abrasive can influence the wear rate of composite resin. The test was carried out on two groups. In one group we employed an ormocer and a hybrid composite that was polished group the composite was polished with the same abrasive paper plus a 1 microm and 0.25 microm grit diamond paste. A three-body wear test was performed using the metal sphere of the wear test machine, the composite and an abrasive. A diamond paste and aluminum oxide dispersion were used as abrasive. Analysis of the results showed that there was no difference between polishing techniques, but revealed a difference between abrasives.

  11. Abrasion-Resistant Coating for Flexible Insulation

    NASA Technical Reports Server (NTRS)

    Mui, D.; Headding, R. E.

    1986-01-01

    Ceramic coating increases durability and heat resistance of flexible high-temperature insulation. Coating compatible with quartz-fabric insulation allowing it to remain flexible during and after repeated exposures to temperatures of 1,800 degree F (982 degree C). Prevents fabric from becoming brittle while increasing resistance to aerodynamic abrasion and loading. Coating consists of penetrating precoat and topcoat. Major ingredients high-purity colloidal silica binder and ground silica filler, which ensure stability and compatibility with fabric at high temperatures. Both precoat and topcoat cured at room temperature.

  12. [Wear behavior of enamel and veneering ceramics].

    PubMed

    Gao, Qing-ping; Chao, Yong-lie; Jian, Xin-chun; Guo, Feng; Meng, Yu-kun

    2007-10-01

    To compare the wear between the enamel and two types of dental decoration porcelains for all-ceramic restorations (Vita-alpha, Vintage AL). Friction coefficients, wear scar width, element concentrations and wear surface evolution were considered relatively to the tribology of that in vivo situation. The wear scars of the samples were characterized by means of dynamic atomic force microscopy (DFM). The different element concentrations of the surface before/after the wear test were determined with energy dispersion spectrometry (EDS). The friction coefficient varied from time in each kind of material. The statistical differences between materials were observed in wear scar width and properties of materials (P<0.05). DFM results showed wear surface of natural tooth full of abrasive particles and denaturation of dental texture. Wear surface of veneering ceramics consisted mainly of abrasive particles, plough and microcracking. EDS results showed that the element concentration of Fe was obviously found on the samples after wear. The main underlying mechanisms of natural teeth wear are abrasive, and denaturation of dental texture. Abrasive wear, adhesion and fatigue of veneering ceramics characterize the wear patterns which plays different role in Vita-alpha and Vintage AL. The wear patterns of veneering ceramics can be described as mild wear.

  13. Wear resistance of a metal surface modified with minerals

    NASA Astrophysics Data System (ADS)

    Kislov, S. V.; Kislov, V. G.; Balasch, P. V.; Skazochkin, A. V.; Bondarenko, G. G.; Tikhonov, A. N.

    2016-02-01

    The article describes the advantages of the new technology of mineral coating of metal products for the friction pair of mechanical systems. It presents the research results of the wear rate of the samples made of 12X13 steel (X12Cr13) with mineral layers, in the experiments with a piston ring sliding inside a cylinder liner with grease. The wear rate of the samples with mineral layers is lower almost by two factors than that of the samples made of grey foundry iron and untreated samples. As the result of slip/rolling abrasion tests of parts with mineral layers under conditions of high contact pressure, a suggestion was made concerning probable mechanics of surface wear.

  14. Wear Characteristics of Metallic Biomaterials: A Review

    PubMed Central

    Hussein, Mohamed A.; Mohammed, Abdul Samad; Al-Aqeeli, Naser

    2015-01-01

    Metals are extensively used in a variety of applications in the medical field for internal support and biological tissue replacements, such as joint replacements, dental roots, orthopedic fixation, and stents. The metals and alloys that are primarily used in biomedical applications are stainless steels, Co alloys, and Ti alloys. The service period of a metallic biomaterial is determined by its abrasion and wear resistance. A reduction in the wear resistance of the implant results in the release of incompatible metal ions into the body that loosen the implant. In addition, several reactions may occur because of the deposition of wear debris in tissue. Therefore, developing biomaterials with high wear resistance is critical to ensuring a long life for the biomaterial. The aim of this work is to review the current state of knowledge of the wear of metallic biomaterials and how wear is affected by the material properties and conditions in terms of the type of alloys developed and fabrication processes. We also present a brief evaluation of various experimental test techniques and wear characterization techniques that are used to determine the tribological performance of metallic biomaterials.

  15. Qualitative Assessment of Wear Resistance and Surface Hardness of Different Commercially Available Dental Porcelain: An in vitro Study.

    PubMed

    Singh, Abhishek; Nagpal, Abhishek; Pawah, Salil; Pathak, Chetan; Issar, Gaurav; Sharma, Pankaj

    2016-09-01

    In an attempt to minimize wear damage to the enamel of antagonist teeth, new low and medium fusing ceramic materials have been developed. Manufacturers usually claim that these ceramics are wear-friendly because of their lower hardness, lower concentrations of crystal phase, and smaller crystal sizes. This study aimed to quantitatively analyze the wear strength of various commercially available dental porcelain with tooth enamel as well as the surface hardness of these dental porcelain. The basic model was designed as a pin on plate arrangement. The tooth specimens were mounted on the stylus which was centered on the ceramic specimen in a wear testing machine. The dental ceramic specimen was centered in the metal die. A load of 40 N was applied at a rate of 80 cycles/minute for 15 minutes. In the current study, mean wear depth (Ra) value, volumetric loss, and surface hardness were obtained by standard quantification method and were statistically evaluated. Ceramco-3 was reported to be most abrasive for enamel; however, Duceram love significantly more abraded itself than the other two, Ceramco-3 and Vita Alpha, and generated the lowest loss of enamel. Also, same abrasive type of wear was revealed for all three variants of tested ceramics. Ceramco-3 was the most abrasive for enamel, while surface roughness (mean wear depth) of Duceram love was maximum and for Ceramco-3 it was minimum. The value of surface roughness for Vita Alpha was in between Duceram love and Ceramco-3. Nonetheless, the mean surface hardness of Duceram love was found to be least and maximum for Vita Alpha. In situations of dental wear and wasting tooth disease (Attrition/Abrasion), Duceram can be applied in lieu of Ceramco-3 so as to prevent worsening of existing dentition. However, in younger patients Vita Alpha would offer maximum durability due to its greater surface hardness.

  16. Increasing in the wear resistance of injection molds made of 1.2343 steel using Ti/TiN/TiCN/nc-TiCN:a-C/nc-TiC:a-C/a-C nanocomposite coating

    NASA Astrophysics Data System (ADS)

    Rupetsov, Velko; Mishev, Georgi; Dishliev, Stefan; Kopanov, Viktor; Chitanov, Vassiliy; Kolaklieva, Lilyana; Pashinski, Chavdar

    2017-02-01

    Injection molds used in production of plastic components are subject of heavy abrasion wear. The increase of their wear resistance significantly reduces the production cost. In the current work are presented research results of the wear resistance of injection molds made of steel 1.2343, coated with Ti/TiN/TiCN/nc-TiCN: a-C/nc-TiC:a -C/a-C. The study of the wear rate was done using the volumetric method and the influence of the trace length was investigated. The coating thickness, nanohardness, elastic modulus and adhesion were also tested. The coating was applied on unhardened ground specimens, hardened ground specimens and hardened polished specimens.

  17. Clinical measurement of tooth wear: Tooth wear indices

    PubMed Central

    López-Frías, Francisco J.; Castellanos-Cosano, Lizett; Martín-González, Jenifer; Llamas-Carreras, José M.

    2012-01-01

    Attrition, erosion, and abrasion result in alterations to the tooth and manifest as tooth wear. Each classification corresponds to a different process with specific clinical features. Classifications made so far have no accurate prevalence data because the indexes do not necessarily measure a specific etiology, or because the study populations can be diverse in age and characteristics. Tooth wears (attrition, erosion and abrasion) is perceived internationally as a growing problem. However, the interpretation and comparison of clinical and epidemiological studies, it is increasingly difficult because of differences in terminology and the large number of indicators/indices that have been developed for the diagnosis, classification and monitoring of the loss of dental hard tissue. These indices have been designed to identify increasing severity and are usually numerical, none have universal acceptance, complicating the evaluation of the true increase in prevalence reported. This article considers the ideal requirements for an erosion index. A literature review is conducted with the aim of analyzing the evolution of the indices used today and discuss whether they meet the clinical needs and research in dentistry. Key words:Tooth wear, tooth wear indices, attrition, erosion, abrasion, abfraction. PMID:24558525

  18. Development of a two-body wet abrasion test method with attention to the effects of reused abradant

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Blau, Peter Julian; Dehoff, Ryan R

    2012-01-01

    Abrasive wear is among the most common and costliest causes for material wastage, and it occurs in many forms. A simple method has been developed to quantify the response of metals and alloys to two-body wet abrasion. A metallographic polishing machine was modified to create a disk-on-flat sliding test rig. Adhesive-backed SiC grinding papers were used under fixed load and speed to rank the abrasive wear of seven alloy steels, some of which are candidates for drill cones for geothermal drilling. Standardized two-body abrasion tests, like those described in ASTM G132, feed unused abrasive into the contact; however, the currentmore » work investigated whether useful rankings could still be obtained with a simpler testing configuration in which specimens repeatedly slide on the same wear path under water-lubricated conditions. Tests using abrasive grit sizes of 120 and 180 resulted in the same relative ranking of the alloys although the coarser grit produced more total wear. Wear decreased when the same abrasive disk was re-used for up to five runs, but the relative rankings of the steels remained the same. This procedure was presented to ASTM Committee G2 on Wear and Erosion as a potential standard test for wet two-body abrasive wear.« less

  19. Cerium Addition Improved the Dry Sliding Wear Resistance of Surface Welding AZ91 Alloy

    PubMed Central

    Zhao, Zhihao; Zhu, Qingfeng; Wang, Gaosong; Tao, Kai

    2018-01-01

    In this study, the effects of cerium (Ce) addition on the friction and wear properties of surface welding AZ91 magnesium alloys were evaluated by pin-on-disk dry sliding friction and wear tests at normal temperature. The results show that both the friction coefficient and wear rate of surfacing magnesium alloys decreased with the decrease in load and increase in sliding speed. The surfacing AZ91 alloy with 1.5% Ce had the lowest friction coefficient and wear rate. The alloy without Ce had the worst wear resistance, mainly because it contained a lot of irregularly shaped and coarse β-Mg17Al12 phases. During friction, the β phase readily caused stress concentration and thus formed cracks at the interface between β phase and α-Mg matrix. The addition of Ce reduced the size and amount of Mg17Al12, while generating Al4Ce phase with a higher thermal stability. The Al-Ce phase could hinder the grain-boundary sliding and migration and reduced the degree of plastic deformation of subsurface metal. Scanning electron microscopy observation showed that the surfacing AZ91 alloy with 1.5% Ce had a total of four types of wear mechanism: abrasion, oxidation, and severe plastic deformation were the primary mechanisms; delamination was the secondary mechanism. PMID:29415492

  20. Abrasion resistance of direct and indirect resins as a function of a sealant veneer.

    PubMed

    Ferraz Caneppele, Taciana Marco; Rocha, Daniel Maranha; Màximo Araujo, Maria Amelia; Valera, Màrcia Carneiro; Salazar Marocho, Susana MarIa

    2014-01-01

    Abrasive wear is one of the most common type of wear that not only affect teeth, as also dental restorations. Thus to investigate one of the etiological factors as tooth brushing procedure is clinical relevant in order to select the best material combination that may prevent damage of resin dental restoration's abrasion. This study evaluated the influence of tooth brushing on mass loss and surface roughness of direct Venus (Vs) and indirect Signum (Sg) resin composites, with and without a surface sealant, Fortify (F). Twenty-four specimens were prepared with each resin composite, using their proprietary curing units, according to manufacturer's instructions. All the specimens were polished and ultrasonically cleaned in distilled water for 5 minutes. Half of the specimens of each resin (n = 12) were covered with F (Vs F and Sg F ), except for the control (C) specimens (Vs C and Sg C ), which were not sealed. Mass loss (ML) as well as surface roughness (Ra ) was measured for all the specimens. Then, the specimens were subjected to toothbrush-dentifrice abrasion, using a testing machine for 67.000 brushing strokes, in an abrasive slurry. After brushing simulation, the specimens were removed from the holder, rinsed thoroughly and blot dried with soft absorbent paper. The abrasion of the material was quantitatively determined with final measurements of ML and surface roughness, using the method described above. ML data were analyzed by two-way analysis of variance (ANOVA) and the analysis indicated that resin composites were not statistically different; however, the specimens sealed with F showed higher ML. Ra mean values of the groups Vs F and Sg F significantly increased. Tooth brushing affects mainly the roughness of the direct and indirect resin composites veneered with a sealant.

  1. Wear of enamel and veneering ceramics after laboratory and chairside finishing procedures.

    PubMed

    Magne, P; Oh, W S; Pintado, M R; DeLong, R

    1999-12-01

    This in vitro study compared the wear of enamel against 3 types of ceramics with high esthetic potential (designed for layering techniques): feldspathic porcelain (Creation), aluminous porcelain (Vitadur alpha), and low-fusing glass (Duceram-LFC). Laboratory finishing (glazing/polishing) and chairside polishing with a Dialite kit were simulated to compare their respective effects on wear. Tooth-material specimen pairs were placed in an artificial mouth using closed-loop servohydraulics. Constant masticatory parameters (13.5 N occlusal force, 0.62 mm lateral excursion; 0.23 second cuspal contact time) were maintained for 300, 000 cycles at a rate of 4 Hz. The occlusal surface of each pair was mapped and digitally recorded before and after each masticatory test. Quantitative changes were measured in terms of depth and volume of wear. Quantitative wear characteristics were assessed by SEM. Significant differences were observed (2-factor ANOVA, P <.05). Duceram-LFC generated increased volume loss of enamel (0.197 mm(3)) compared with Creation (0.135 mm(3)) and Vitadur alpha (0.153 mm(3)). Creation exhibited the lowest ceramic wear and lowest combined volume loss (0.260 mm(3); the sum of the data for enamel and the opposing material) compared with Duceram-LFC (0.363 mm(3)) and Vitadur alpha (0.333 mm(3)). The most significant differences among materials were observed in volume loss, not in depth of wear. For all 3 ceramic systems, qualitative SEM evaluation revealed an abrasive type of wear. Wear characteristics of chairside polished specimens were similar to those of laboratory finished specimens (glazed and polished). Duceram-LFC was the most abrasive ceramic for the antagonistic tooth. Creation ceramic was the least abrasive material and most resistant to wear. Defects, brittleness, and the possibly insufficient toughness of LFC may explain its increased abrasiveness. Laboratory and chairside finishing procedures generated similar results.

  2. Low friction wear resistant graphene films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sumant, Anirudha V.; Berman, Diana; Erdemir, Ali

    A low friction wear surface with a coefficient of friction in the superlubric regime including graphene and nanoparticles on the wear surface is provided, and methods of producing the low friction wear surface are also provided. A long lifetime wear resistant surface including graphene exposed to hydrogen is provided, including methods of increasing the lifetime of graphene containing wear surfaces by providing hydrogen to the wear surface.

  3. Friction and Wear

    NASA Technical Reports Server (NTRS)

    Pomey, Jacques

    1952-01-01

    From the practical point of view, this analysis shows that each problem of friction or wear requires its particular solution. There is no universal solution; one or other of the factors predominates and defines the choice of the solution. In certain cases, copper alloys of great thermal conductivity are preferred; in others, plastics abundantly supplied with water. Sometimes, soft antifriction metals are desirable to distribute the load; at other times, hard metals with high resistance to abrasion or heat.

  4. Abrasion and deformed layer formation of manganese-zinc ferrite in sliding contact with lapping tapes

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.; Tanaka, K.

    1986-01-01

    Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and the deformed layers produced in single-crystal Mn-Zn ferrite simulated heads during contact with lapping tapes. The crystaline state of the head is changed drastically during the abrasion process. Crystalline states ranging from nearly amorphous to highly textured polycrystalline can be produced on the wear surface of a single-crystal Mn-Zn ferrite head. The total thickness of the deformed layer was approximately 0.8 microns. This thickness increased as the load and abrasive grit size increased. The anisotropic wear of the ferrite was found to be inversely proportional to the hardness of the wear surface. The wear was lower in the order 211 111 10 0110. The wear of the ferrite increased markedly with an increase in sliding velocity and abrasive grit size.

  5. Wear behavior of austenite containing plate steels

    NASA Astrophysics Data System (ADS)

    Hensley, Christina E.

    As a follow up to Wolfram's Master of Science thesis, samples from the prior work were further investigated. Samples from four steel alloys were selected for investigation, namely AR400F, 9260, Hadfield, and 301 Stainless steels. AR400F is martensitic while the Hadfield and 301 stainless steels are austenitic. The 9260 exhibited a variety of hardness levels and retained austenite contents, achieved by heat treatments, including quench and tempering (Q&T) and quench and partitioning (Q&P). Samples worn by three wear tests, namely Dry Sand/Rubber Wheel (DSRW), impeller tumbler impact abrasion, and Bond abrasion, were examined by optical profilometry. The wear behaviors observed in topography maps were compared to the same in scanning electron microscopy micrographs and both were used to characterize the wear surfaces. Optical profilometry showed that the scratching abrasion present on the wear surface transitioned to gouging abrasion as impact conditions increased (i.e. from DSRW to impeller to Bond abrasion). Optical profilometry roughness measurements were also compared to sample hardness as well as normalized volume loss (NVL) results for each of the three wear tests. The steels displayed a relationship between roughness measurements and observed wear rates for all three categories of wear testing. Nanoindentation was used to investigate local hardness changes adjacent to the wear surface. DSRW samples generally did not exhibit significant work hardening. The austenitic materials exhibited significant hardening under the high impact conditions of the Bond abrasion wear test. Hardening in the Q&P materials was less pronounced. The Q&T microstructures also demonstrated some hardening. Scratch testing was performed on samples at three different loads, as a more systematic approach to determining the scratching abrasion behavior. Wear rates and scratch hardness were calculated from scratch testing results. Certain similarities between wear behavior in scratch testing

  6. Wear and corrosion behaviour of tungsten carbide based coatings with different metallic binder

    NASA Astrophysics Data System (ADS)

    Kamdi, Z.; Apandi, M. N. M.; Ibrahim, M. D.

    2017-12-01

    Tungsten carbide based coating has been well known as wear and corrosion resistance materials. However, less study is done on comparing the coating with different binder. Thus, in this work the wear and corrosion behaviour of high velocity oxy-fuel (HVOF) coatings, namely (i) tungsten carbide cobalt and (ii) tungsten carbide nickel will be evaluated. Both coatings were characterised using X-ray Diffractometer (XRD) and Scanning Electron Microscope (SEM). The wear behaviour has been examined using the modified grinder machine by weight loss measurement. Two types of abrasive have been used that include 3 g by weight alumina and silica. While for the corrosion behaviour, it is monitored by three electrodes of electrochemical test and immersion test for 30 days in an acidic environment. The electrolyte used was 0.5 M sulphuric acids (H2SO4). It was found that the cobalt binder shows higher wear resistance compares to the nickel binder for both slurry types. The harder alumina compared to silica results in higher wear rate with removal of carbide and binder is about the same rate. For silica abrasive, due to slightly lower hardness compared to the carbide, the wear is dominated by binder removal followed by carbide detachment. For corrosion, the nickel binder shows four times higher wear resistance compared to the cobalt binder as expected due to its natural behaviour. These finding demonstrate that the selection of coating to be used in different application in this case, wear and corrosion shall be chosen carefully to maximize the usage of the coating.

  7. [Comparison of wear resistance and flexural strength of three kinds of bulk-fill composite resins].

    PubMed

    Zhang, Huan; Zhang, Meng-Long; Qiu, Li-Hong; Yu, Jing-Tao; Zhan, Fu-Liang

    2016-06-01

    To compare the abrasion resistance and flexure strength of three bulk-fill resin composites with an universal nano-hybrid composite resins. The specimens were prepared with three kinds of bulk fill composites (SDR , sonicfill, Tetric N-Ceram Bulk Fill) and an universal nano-hybrid composite resins(Herculite Precis). 10 mm in diameter × 2mm in height specimens were prepared for abrasion resistance, while 2 mm in width × 2 mm in depth×25 mm in length specimens were prepared for flexure strength. The specimens were mounted in a bal1-on-disc wear testing machine and abraded with the media artificial saliva(50 N loads, 10000 cycles).Flexural test was performed with an Universal Testing Machine at a cross-head speed of 1mm/min. One-way variance analysis was used to determine the statistical differences of volume loss and flexural strength among groups with SPSS 13.0 software package(P<0.05). The volume loss was as follows: SDR (1.2433±0.11) mm30.05). With regard to wear resistance and flexural strength, Tetric N-Ceram Bulk Fill is recommended as an alternative for posterior restorations.

  8. The worn dentition--pathognomonic patterns of abrasion and erosion.

    PubMed

    Abrahamsen, Thomas C

    2005-01-01

    Historically, the dental literature has revealed various causes of tooth wear, yet it has failed to provide a conclusive method of differentiation and diagnosis of the condition. The categories of tooth wear encountered most commonly in dental practice are abrasion and erosion. The major causes of wear from abrasion are bruxism and toothpaste abuse, and the major causes of wear from erosion are regurgitation, coke-swishing and fruit-mulling. Through in-depth clinical study of these causes, this paper provides a diagnostic system that will enable dental professionals to determine and differentiate the exact aetiology of the worn dentition simply by the recognition of the pathognomonic wear patterns on diagnostic casts, which are based upon the position and quantity of the non-carious loss of tooth structure.

  9. Study of Dominant Factors Affecting Cerchar Abrasivity Index

    NASA Astrophysics Data System (ADS)

    Rostami, Jamal; Ghasemi, Amireza; Alavi Gharahbagh, Ehsan; Dogruoz, Cihan; Dahl, Filip

    2014-09-01

    The Cerchar abrasion index is commonly used to represent rock abrasion for estimation of bit life and wear in various mining and tunneling applications. Although the test is simple and fast, there are some discrepancies in the test results related to the equipment used, condition of the rock surface, operator skills, and procedures used in conducting and measuring the wear surface. This paper focuses on the background of the test and examines the influence of various parameters on Cerchar testing including pin hardness, surface condition of specimens, petrographical and geomechanical properties, test speed, applied load, and method of measuring wear surface. Results of Cerchar tests on a set of rock specimens performed at different laboratories are presented to examine repeatability of the tests. In addition, the preliminary results of testing with a new device as a potential alternative testing system for rock abrasivity measurement are discussed.

  10. In vitro wear of new indirect resin composites.

    PubMed

    Jain, V; Platt, J A; Moore, B K; Borges, G A

    2009-01-01

    This in vitro study evaluated the toothbrush abrasion wear, three-body Alabama wear and two-body pin-on-disc wear of four commercial indirect resin composites. Enamel shades of Radica (R), Sculpture Plus (S), Belleglass-NG (B) and Gradia Indirect (G) were used. For measuring wear due to toothbrush abrasion, six specimens of each group were fabricated, then brushed in a toothbrush abrasion machine for 20,000 cycles. Material loss was determined by weighing and conversion to volume loss. Three-body wear was measured on six samples for each group using an Alabama-type wear testing machine for 400,000 cycles. Wear depth was measured with a contact profilometer. For two-body wear, five disc specimens were prepared and tested in a two-body wear-testing machine against hydroxypatite sliders for 25,000 cycles. Data were analyzed with one-way analysis of variance (ANOVA) and Tukey test (alpha=0.05). Wear was the highest in Sculpture Plus by all three methods tested and the lowest wear was observed in Belleglass-NG. No statistical difference in wear was noted from Radica.

  11. Abrasion Resistance and Mechanical Properties of Waste-Glass-Fiber-Reinforced Roller-compacted Concrete

    NASA Astrophysics Data System (ADS)

    Yildizel, S. A.; Timur, O.; Ozturk, A. U.

    2018-05-01

    The potential use of waste glass fibers in roller-compacted concrete (RCC) was investigated with the aim to improve its performance and reduce environmental effects. The research was focused on the abrasion resistance and compressive and flexural strengths of the reinforced concrete relative to those of reference mixes without fibers. The freeze-thaw resistance of RCC mixes was also examined. It was found that the use of waste glass fibers at a rate of 2 % increased the abrasion resistance of the RCC mixes considerably.

  12. Comparative study of the wear behavior of composites for posterior restorations.

    PubMed

    Turssi, Cecilia P; Faraoni-Romano, Juliana J; de Menezes, Márcio; Serra, Mônica C

    2007-01-01

    This investigation sought to compare the abrasive wear rates of resin composites designed for posterior applications. Seventy-five specimens were fabricated with conventional hybrid (Charisma and Filtek Z250) or packable composites (Filtek P60, Solitaire II and Tetric Ceram HB), according to a randomized complete block design (n = 15). Specimens were finished and polished metallographically and subjected to abrasive wear which was performed under a normal load of 13N at a frequency of 2 Hz using a pneumatic device (MSM/Elquip) in the presence of a mucin-containing artificial saliva. Wear was quantified profilometrically in five different locations of each specimen after 1,000, 5,000, 10,000, 50,000 and after every each 50,000 through 250,000 cycles. A split-plot ANOVA showed a significant difference between the wear resistance of composites (alpha = 0.05). Tukey's test ascertained that while the composites Filtek Z250 and Charisma wore significantly less than any other of the materials tested, Tetric Ceram HB experienced the greatest wear rates. Filtek P60 and Solitaire II showed intermediate rates of material removal. The wear pattern of composites proved to be biphasic with the primary phase having the faster wear rate. In conclusion, packable resin composites may not have superior wear compared to conventional hybrid composites.

  13. An in situ/ex vivo comparison of the ability of regular and light colas to induce enamel wear when erosion is combined with abrasion.

    PubMed

    Rios, Daniela; Santos, Flávia Cardoso Zaidan; Honório, Heitor Marques; Magalhães, Ana Carolina; Wang, Linda; de Andrade Moreira Machado, Maria Aparecida; Buzalaf, Marilia Afonso Rabelo

    2011-03-01

    To evaluate whether the type of cola drink (regular or diet) could influence the wear of enamel subjected to erosion followed by brushing abrasion. Ten volunteers wore intraoral devices that each had eight bovine enamel blocks divided into four groups: ER, erosion with regular cola; EAR, erosion with regular cola plus abrasion; EL, erosion with light cola; and EAL, erosion with light cola plus abrasion. Each day for 1 week, half of each device was immersed in regular cola for 5 minutes. Then, two blocks were brushed using a fluoridated toothpaste and electric toothbrush for 30 seconds four times daily. Immediately after, the other half of the device was subjected to the same procedure using a light cola. The pH, calcium, phosphorus, and fluoride concentrations of the colas were analyzed using standard procedures. Enamel alterations were measured by profilometry. Data were tested using two-way ANOVA and Bonferroni test (P<.05). Regarding chemical characteristics, light cola presented pH 3.0, 13.7 mg Ca/L, 15.5 mg P/L, and 0.31 mg F/L, while regular cola had pH 2.6, 32.1 mg Ca/L, 18.1 mg P/L, and 0.26 mg F/L. The light cola promoted less enamel loss (EL, 0.36 Μm; EAL, 0.39 Μm) than its regular counterpart (ER, 0.72 Μm; EAR, 0.95 Μm) for both conditions. There was not a significant difference (P>.05) between erosion and erosion plus abrasion for light cola. However, for regular cola, erosion plus abrasion resulted in higher enamel loss than erosion alone. The data suggest that light cola promoted less enamel wear even when erosion was followed by brushing abrasion.

  14. Wear Resistant Rubber Tank Track Pads

    DTIC Science & Technology

    1975-10-01

    began to de- crease significantly during the winter months of 1973-1974. The December 1973 issie of Rubber Age carried the statement that the ready...to tear or abrasion. Because EPDM vulcanizates are inherently ozone resistant and have excellent age resistance, even at temperatures as high as...attempts to improve the tear resistance of this blend would be worthwhile. In an article1--’ appearing in the May 1973 issue of Rubber Age , the intro

  15. Effects of sintering temperature on the microstructural evolution and wear behavior of WCp reinforced Ni-based coatings

    NASA Astrophysics Data System (ADS)

    Chen, Chuan-hui; Bai, Yang; Ye, Xu-chu

    2014-12-01

    This article focuses on the microstructural evolution and wear behavior of 50wt%WC reinforced Ni-based composites prepared onto 304 stainless steel substrates by vacuum sintering at different sintering temperatures. The microstructure and chemical composition of the coatings were investigated by X-ray diffraction (XRD), differential thermal analysis (DTA), scanning and transmission electron microscopy (SEM and TEM) equipped with energy-dispersive X-ray spectroscopy (EDS). The wear resistance of the coatings was tested by thrust washer testing. The mechanisms of the decomposition, dissolution, and precipitation of primary carbides, and their influences on the wear resistance have been discussed. The results indicate that the coating sintered at 1175°C is composed of fine WC particles, coarse M6C (M=Ni, Fe, Co, etc.) carbides, and discrete borides dispersed in solid solution. Upon increasing the sintering temperature to 1225°C, the microstructure reveals few incompletely dissolved WC particles trapped in larger M6C, Cr-rich lamellar M23C6, and M3C2 in the austenite matrix. M23C6 and M3C2 precipitates are formed in both the γ/M6C grain boundary and the matrix. These large-sized and lamellar brittle phases tend to weaken the wear resistance of the composite coatings. The wear behavior is controlled simultaneously by both abrasive wear and adhesive wear. Among them, abrasive wear plays a major role in the wear process of the coating sintered at 1175°C, while the effect of adhesive wear is predominant in the coating sintered at 1225°C.

  16. High-temperature frictional wear behavior of MCrAlY-based coatings deposited by atmosphere plasma spraying

    NASA Astrophysics Data System (ADS)

    Tao, Chong; Wang, Lei; Song, Xiu

    2017-02-01

    Al2O3-Cr2O3/NiCoCrAlYTa coatings were prepared via atmosphere plasma spraying (APS). The microstructure and phase composition of the coatings were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), laser confocal scanning microscopy (LSCM), and transmission electron microscopy (TEM). The dry frictional wear behavior of the coatings at 500°C in static air was investigated and compared with that of 0Cr25Ni20 steel. The results show that the coatings comprise the slatted layers of oxide phases, unmelted particles, and pores. The hot abrasive resistance of the coatings is enhanced compared to that of 0Cr25Ni20, and their mass loss is approximately one-fifteenth that of 0Cr25Ni20 steel. The main wear failure mechanisms of the coatings are abrasive wear, fatigue wear, and adhesive wear.

  17. Comparative wear resistance of reinforced glass ionomer restorative materials.

    PubMed

    Yap, A U; Teo, J C; Teoh, S H

    2001-01-01

    This study investigated the wear resistance of three restorative reinforced glass ionomer cements (Fuji IX GP FAST [FJ], Miracle Mix [MM] and Ketac Silver [KS]). Microfilled (Silux [SX]) and mini-filled (Z100 [ZO]) composites were used for comparison. Six specimens were made for each material. The specimens were conditioned for one week in distilled water at 37 degrees C and subjected to wear testing at 20 MPa contact stress against SS304 counterbodies using a reciprocal compression-sliding wear instrumentation. Distilled water was used as lubricant. Wear depth (microm) was measured using profilometry every 2,000 cycles up to 10,000 cycles. Results were analyzed using ANOVA/Scheffe's test (p<0.05). After 10,000 cycles of wear testing, ranking was as follows: KS>ZO>MM>FJ>SX. Wear ranged from 26.1 microm for SX to 71.5 microm for KS. The wear resistance of KS was significantly lower than FJ, MM and SX at all wear intervals. Although KS had significantly more wear than ZO at 2,000 to 6,000 cycles, no significant difference in wear was observed between these two materials at 8,000 and 10,000 cycles. Sintering of silver particles to glass ionomer cement (KS) did not appear to improve wear resistance. The simple addition of amalgam alloy to glass ionomer may improve wear resistance but results in poor aesthetics (silver-black color). FJ, which relies on improved chemistry instead of metal fillers, showed comparable wear resistance to the composites evaluated and is tooth-colored. It may serve as a potential substitute for composites in low-stress situations where fluoride release is desirable and aesthetic requirements are not high.

  18. Wear resistance of hydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Martinez, MA; Abenojar, J.; Pantoja, M.; López de Armentia, S.

    2017-05-01

    Nature has been an inspiration source to develop artificial hydrophobic surfaces. During the latest years the development of hydrophobic surfaces has been widely researched due to their numerous ranges of industrial applications. Industrially the use of hydrophobic surfaces is being highly demanded. This is why many companies develop hydrophobic products to repel water, in order to be used as coatings. Moreover, these coating should have the appropriated mechanical properties and wear resistance. In this work wear study of a hydrophobic coating on glass is carried out. Hydrophobic product used was Sika Crystal Dry by Sika S.A.U. (Alcobendas, Spain). This product is currently used on car windshield. To calculate wear resistance, pin-on-disk tests were carried out in dry and water conditions. The test parameters were rate, load and sliding distance, which were fixed to 60 rpm, 5 N and 1000 m respectively. A chamois was used as pin. It allows to simulate a real use. The friction coefficient and loss weight were compared to determinate coating resistance

  19. Method of protecting surfaces from abrasion and abrasion resistant articles of manufacture

    DOEpatents

    Hirschfeld, T.B.

    1988-06-09

    Surfaces of fabricated structures are protected from damage by impacting particulates by a coating of hard material formed as a mass of thin flexible filaments having root ends secured to the surface and free portions which can flex and overlap to form a resilient cushioning mat which resembles hair or fur. The filamentary coating covers the underlying surface with hard abrasion resistance material while also being compliant and capable of local accommodation to particle impacts. The coating can also function as thermal and/or acoustical insulation and has a friction reducing effect. 11 figs.

  20. Microstructure and wear property of Fe-Cr13-C hardfacing alloy reinforced by WC particles

    NASA Astrophysics Data System (ADS)

    Yang, Ke; Li, Jiaqi; Bao, Yefeng; Jiang, Yongfeng

    2017-07-01

    Tungsten as the most effective carbide-forming element was added in the Fe-Cr13-C hardfacing alloy to precipitate WC particles. Optical microscope (OM), scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS) were used to investigate the microstructures of the hardfacing alloy. The wear resistance was tested through a slurry rubber wheel abrasion test machine, and the wear behavior was also studied. The results indicate that the microstructures of the hardfacing alloy consist of lath martensite, residual austenite and WC particles. The wear resistance can be significantly improved through the addition of tungsten element being provided by the precipitation of WC particles. And the predominant wear mechanism was microcutting with shallow grooves and spalling.

  1. Tooth brush abrasion of paint-on resins for shade modification of crown and bridge resins.

    PubMed

    Fujii, Koichi; Ban, Seiji; McCabe, John F

    2003-09-01

    The purpose of this study was to evaluate the surface roughness and resistance to toothbrush abrasion of three experimental paint-on composite resins developed for the shade modification of crown and bridge resins. The paint-on resins had less filler volume fraction than restorative composites or the crown and bridge resins and consequently were of low viscosity. The maximum surface roughness (Rmax) and the maximum depth loss by abrasion for the paint-on resins following 40,000 cycles of brushing ranged from 2.45 to 4.07 microm and 8.63 to 13.67 microm, respectively. Rmax values were 37.7-67.5% lower than that for the crown and bridge resin subjected to the same test. Wear depth was 19.9-49.4% lower than for the crown and bridge resin. These results suggest that the paint-on resins are expected to have adequate resistance to toothbrush abrasion and may therefore be suitable for clinical use.

  2. Effect of ceramic coating by aerosol deposition on abrasion resistance of a resin composite material.

    PubMed

    Taira, Yohsuke; Hatono, Hironori; Mizukane, Masahiro; Tokita, Masahiro; Atsuta, Mitsuru

    2006-12-01

    Aerosol deposition (AD coating) is a novel technique to coat solid substances with a ceramic film. The purpose of the present study was to investigate the effect of AD coating on abrasion resistance of a resin composite material. A 5-microm-thick aluminum oxide layer was created on the polymerized resin composite. The specimen was cyclically abraded using a toothbrush abrasion simulator for 100,000 cycles. Abraded surface was then measured with a profilometer to determine the average roughness (Ra) and maximum roughness (Rmax). It was found that abrasion cycling increased the Ra value of the No-AD-coating group, but decreased the Ra and Rmax values of the AD coating group. Moreover, the AD coating group showed significantly smaller Ra and Rmax values after 100,000 abrasion cycles as compared to the No-coating control group. Microscopic observation supported these findings. In conclusion, the resistance of the resin composite against toothbrush abrasion was improved by AD coating.

  3. Wear behavior of pressable lithium disilicate glass ceramic.

    PubMed

    Peng, Zhongxiao; Izzat Abdul Rahman, Muhammad; Zhang, Yu; Yin, Ling

    2016-07-01

    This article reports effects of surface preparation and contact loads on abrasive wear properties of highly aesthetic and high-strength pressable lithium disilicate glass-ceramics (LDGC). Abrasive wear testing was performed using a pin-on-disk device in which LDGC disks prepared with different surface finishes were against alumina pins at different contact loads. Coefficients of friction and wear volumes were measured as functions of initial surface finishes and contact loads. Wear-induced surface morphology changes in both LDGC disks and alumina pins were characterized using three-dimensional laser scanning microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results show that initial surface finishes of LDGC specimens and contact loads significantly affected the friction coefficients, wear volumes and wear-induced surface roughness changes of the material. Both wear volumes and friction coefficients of LDGC increased as the load increased while surface roughness effects were complicated. For rough LDGC surfaces, three-body wear was dominant while for fine LDGC surfaces, two-body abrasive wear played a key role. Delamination, plastic deformation, and brittle fracture were observed on worn LDGC surfaces. The adhesion of LDGC matrix materials to alumina pins was also discovered. This research has advanced our understanding of the abrasive wear behavior of LDGC and will provide guidelines for better utilization and preparation of the material for long-term success in dental restorations. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 968-978, 2016. © 2015 Wiley Periodicals, Inc.

  4. Study on Composition, Microstructure and Wear Behavior of Fe-B-C Wear-Resistant Surfacing Alloys

    NASA Astrophysics Data System (ADS)

    Zhuang, Minghui; Li, Muqin; Wang, Jun; Ma, Zhen; Yuan, Shidan

    2017-12-01

    Fe-B-C alloy layers with various microstructures were welded on Q235 steel plates using welding powders/H08Mn2Si and welding wires composite surfacing technology. The relationship existing between the chemical composition, microstructure and wear resistance of the surfacing alloy layers was investigated by scanning electron microscopy, x-ray diffraction, electron backscatter diffraction and wear tests. The results demonstrated that the volume fractions and morphologies of the microstructures in the surfacing alloy layers could be controlled by adjusting the boron and carbon contents in the welding powders, which could further regulate the wear resistance of the surfacing alloy layers. The typical microstructures of the Fe-B-C surfacing alloy layers included dendritic Fe, rod-like Fe2B, fishbone-like Fe2B and daisy-like Fe3(C, B). The wear resistance of the alloy layers with various morphologies differed. The wear resistance order of the different microstructures was: rod-like Fe2B > fishbone-like Fe2B > daisy-like Fe3(C, B) > dendritic Fe. A large number of rod-like Fe2B with high microhardness could be obtained at the boron content of 5.70 5.90 wt.% and the carbon content of 0.50 0.60wt.%. The highest wear resistance of the Fe-B-C alloy layers reached the value of 24.1 g-1, which demonstrates the main microscopic cutting wear mechanism of the Fe-B-C alloy layers.

  5. Study on the potential inhibition of root dentine wear adjacent to fluoride-containing restorations.

    PubMed

    Turssi, Cecilia Pedroso; Hara, Anderson Takeo; Domiciano, Silvia Jorge; Serra, Mônica Campos

    2008-01-01

    The purpose of this in vitro study was to determine whether the vicinity of root dentine that had been restored with fluoride-releasing materials was at reduced risk for erosive/abrasive wear compared to root dentine restored with a non-fluoride-containing material. According to a randomized complete block design, standardized cavities prepared on the surface of 150 bovine root dentine slabs were restored with glass-ionomer cement, resin-modified glass ionomer, polyacid-modified resin composite, fluoride-containing or conventional composite. Specimens were coated with two layers of an acid-resistant nail varnish exposing half of the dentine surface and half of the restoration. Subsequently, specimens were either eroded in an acidic drink or left uneroded, then exposed to artificial saliva and abraded in a toothbrushing machine. Wear depth in the vicinity of restorations was quantified by a stylus profilometer, based on the nonabraded areas surrounding the erosion/abrasion region. Two-way ANOVA did not demonstrate significant interaction between restoratives and eroded-uneroded dentine (p=0.5549) nor significant difference among restorative materials (p=0.8639). Tukey's test ascertained that the wear depth was higher for eroded than for uneroded groups. Fluoride-releasing materials seemed to negligibly inhibit wear in the vicinity of restored root dentine subjected to erosive/abrasive challenges.

  6. Risk Assessment for Tooth Wear.

    PubMed

    Kontaxopoulou, Isavella; Alam, Sonia

    2015-08-01

    Tooth wear has an increasing prevalence in the UK population. The aetiology is commonly multifactorial, and the aetiopathology is through a combination of erosion, attrition, abrasion and abfraction. Erosion is associated with intrinsic or extrinsic acids, and therefore subjects with reflux disease and eating disorders are at increased risk. Fruit juice, fruits and carbonated drink consumption, frequency of consumption and specific habits are also risk factors. Attrition is more prevalent in bruxists. Other habits need to be considered when defining the risk of tooth wear. Abrasion is usually associated with toothbrushing and toothpastes, especially in an already acidic environment. Patients with extensive lesions that affect dentin may be at higher risk, as well as those presenting with unstained lesions. Monitoring of the progress of tooth wear is recommended to identify those with active tooth wear. Indices for tooth wear are a helpful aid.

  7. Neural network approximation of tip-abrasion effects in AFM imaging

    NASA Astrophysics Data System (ADS)

    Bakucz, Peter; Yacoot, Andrew; Dziomba, Thorsten; Koenders, Ludger; Krüger-Sehm, Rolf

    2008-06-01

    The abrasion (wear) of tips used in scanning force microscopy (SFM) directly influences SFM image quality and is therefore of great relevance to quantitative SFM measurements. The increasing implementation of automated SFM measurement schemes has become a strong driving force for increasing efforts towards the prediction of tip wear, as it needs to be ensured that the probe is exchanged before a level of tip wear is reached that adversely affects the measurement quality. In this paper, we describe the identification of tip abrasion in a system of SFM measurements. We attempt to model the tip-abrasion process as a concatenation of a mapping from the measured AFM data to a regression vector and a nonlinear mapping from the regressor space to the output space. The mapping is formed as a basis function expansion. Feedforward neural networks are used to approximate this mapping. The one-hidden layer network gave a good quality of fit for the training and test sets for the tip-abrasion system. We illustrate our method with AFM measurements of both fine periodic structures and randomly oriented sharp features and compare our neural network results with those obtained using other methods.

  8. Wear resistance of CuZr-based amorphous-forming alloys against bearing steel in 3.5% NaCl solution

    NASA Astrophysics Data System (ADS)

    Ji, Xiulin; Wang, Hui; Bao, Yayun; Zheng, Dingcong

    2017-11-01

    To investigate the amorphous-crystalline microstructure on the tribocorrosion of bulk metallic glasses (BMGs), 6 mm diameter rods of Cu46-xZr47Al7Agx (x = 0, 2, 4) amorphous-forming alloys with in situ crystalline and amorphous phases were fabricated by arc-melting and Cu-mould casting. Using a pin-on-disc tribometer, the tribo-pair composed by CuZr-based amorphous-forming alloys and AISI 52100 steel were studied in 3.5% NaCl solution. With the increase of Ag content from 0 to 4 at.%, the compressive fracture strength and the average hardness decrease firstly and then increase. Moreover, 4 at.% Ag addition increases the amount of amorphous phase obviously and inhibits the formation of brittle crystalline phase, resulting in the improvement of corrosion resistance and the corrosive wear resistance. The primary wear mechanism of the BMG composites is abrasive wear accompanying with corrosive wear. The tribocorrosion mass loss of Cu42Zr47Al7Ag4 composite is 1.5 mg after 816.8 m sliding distance at 0.75 m s-1 sliding velocity under 10 N load in NaCl solution. And the volume loss evaluated from the mass loss is about 20 times lower than that of AISI 304 SS. Thus, Cu42Zr47Al7Ag4 composite may be a good candidate in the tribology application under marine environment.

  9. Improvement of wear resistance of plasma-sprayed molybdenum blend coatings

    NASA Astrophysics Data System (ADS)

    Ahn, Jeehoon; Hwang, Byoungchul; Lee, Sunghak

    2005-06-01

    The wear resistance of plasma sprayed molybdenum blend coatings applicable to synchronizer rings or piston rings was investigated in this study. Four spray powders, one of which was pure molybdenum and the others blended powders of bronze and aluminum-silicon alloy powders mixed with molybdenum powders, were sprayed on a low-carbon steel substrate by atmospheric plasma spraying. Microstructural analysis of the coatings showed that the phases formed during spraying were relatively homogeneously distributed in the molybdenum matrix. The wear test results revealed that the wear rate of all the coatings increased with increasing wear load and that the blended coatings exhibited better wear resistance than the pure molybdenum coating, although the hardness was lower. In the pure molybdenum coatings, splats were readily fractured, or cracks were initiated between splats under high wear loads, thereby leading to the decrease in wear resistance. On the other hand, the molybdenum coating blended with bronze and aluminum-silicon alloy powders exhibited excellent wear resistance because hard phases such as CuAl2 and Cu9Al4 formed inside the coating.

  10. Diagnosis and management of dental wear.

    PubMed

    Harpenau, Lisa A; Noble, Warden H; Kao, Richard T

    2011-04-01

    Dental wear is loss of tooth structure resulting from erosion, attrition, abrasion, and, possibly, abfraction. Clinical/experimental data suggest no single damaging mechanism but rather simultaneous interaction of these destructive processes. The most important interaction is abrasion/attrition potentiated by dental erosion. Awareness of this pathosis is not well-appreciated by the public and dental professionals because the signs may be subtle. This article focuses on the recognition, diagnosis, and management of dental wear.

  11. Wear Characteristic of Stellite 6 Alloy Hardfacing Layer by Plasma Arc Surfacing Processes

    PubMed Central

    Zhou, Xiaowei

    2017-01-01

    The microstructure and wear resistance of Stellite 6 alloy hardfacing layer at two different temperatures (room temperature and 300°C) were investigated by plasma arc surfacing processes on Q235 Steel. Tribological test was conducted to characterize the wear property. The microstructure of Stellite 6 alloy coating mainly consists of α-Co and (Cr, Fe)7C3 phases. The friction coefficient of Stellite 6 alloys fluctuates slightly under different loads at 300°C. The oxide layer is formed on the coating surface and serves as a special lubricant during the wear test. Abrasive wear is the dominant mechanism at room temperature, and microploughing and plasticity are the key wear mechanisms at 300°C. PMID:29359005

  12. Mechanical modelling of tooth wear

    PubMed Central

    Kallonen, Aki

    2016-01-01

    Different diets wear teeth in different ways and generate distinguishable wear and microwear patterns that have long been the basis of palaeodiet reconstructions. Little experimental research has been performed to study them together. Here, we show that an artificial mechanical masticator, a chewing machine, occluding real horse teeth in continuous simulated chewing (of 100 000 chewing cycles) is capable of replicating microscopic wear features and gross wear on teeth that resemble wear in specimens collected from nature. Simulating pure attrition (chewing without food) and four plant material diets of different abrasives content (at n = 5 tooth pairs per group), we detected differences in microscopic wear features by stereomicroscopy of the chewing surface in the number and quality of pits and scratches that were not always as expected. Using computed tomography scanning in one tooth per diet, absolute wear was quantified as the mean height change after the simulated chewing. Absolute wear increased with diet abrasiveness, originating from phytoliths and grit. In combination, our findings highlight that differences in actual dental tissue loss can occur at similar microwear patterns, cautioning against a direct transformation of microwear results into predictions about diet or tooth wear rate. PMID:27411727

  13. New Oxide Ceramic Developed for Superior High-Temperature Wear Resistance

    NASA Technical Reports Server (NTRS)

    Sayir, Ali; Miyoshi, Kazuhisa; Farmer, Serene C.

    2003-01-01

    Ceramics, for the most part, do not have inherently good tribological properties. For example friction coefficients in excess of 0.7 have been reported for silicon nitride sliding on silicon nitride or on bearing steel (ref. 1). High friction is always accompanied by considerable wear. Despite their inherently poor tribological properties, the high strength and high toughness of silicon nitride (Si3N4) ceramics has led to their successful use in tribological applications (refs. 1 to 4). The upper temperature limit for the application of Si3N4 as wear-resistant material is limited by reaction with the tribological environment (ref. 3). Silicon nitride is known to produce a thin silicon dioxide film with easy shear capability that results in low friction and low wear in a moist environment (ref. 5). At elevated temperatures, the removal of the reaction product that acts as lubricant causes the friction coefficient to increase and, consequently, the wear performance to become poor. New materials are sought that will have wear resistance superior to that of Si3N4 at elevated temperatures and in harsh environments. A new class of oxide ceramic materials has been developed with potential for excellent high-temperature wear resistance. The new material consists of a multicomponent oxide with a two-phase microstructure, in which the wear resistance of the mixed oxide is significantly higher than that of the individual constituents. This is attributed to the strong constraining effects provided by the interlocking microstructures at different length scales, to the large aspect ratio of the phases, to the strong interphase bonding, and to the residual stresses. Fretting wear tests were conducted by rubbing the new ceramic material against boron carbide (B4C). The new ceramic material produced a wear track groove on B4C, suggesting significantly higher wear resistance for the oxide ceramic. The new material did not suffer from any microstructural degradation after the wear

  14. Control of brushing variables for the in vitro assessment of toothpaste abrasivity using a novel laboratory model.

    PubMed

    Parry, Jason; Harrington, Edward; Rees, Gareth D; McNab, Rod; Smith, Anthony J

    2008-02-01

    Design and construct a tooth-brushing simulator incorporating control of brushing variables including brushing force, speed and temperature, thereby facilitating greater understanding of their importance in toothpaste abrasion testing methodologies. A thermostable orbital shaker was selected as a base unit and 16- and 24-specimen brushing rigs were constructed to fit inside, consisting of: a square bath partitioned horizontally to provide brushing channels, specimen holders for 25 mm diameter mounted specimens to fit the brushing channels and individually weighted brushing arms, able to support four toothbrush holders suspended over the brushing channels. Brush head holders consisted of individually weighted blocks of Delrin, or PTFE onto which toothbrush heads were fixed. Investigating effects of key design criteria involved measuring abrasion depths of polished human enamel and dentine. The brushing simulator demonstrated good reproducibility of abrasion on enamel and dentine across consecutive brushing procedures. Varying brushing parameters had a significant impact on wear results: increased brushing force demonstrated a trend towards increased wear, with increased reproducibility for greater abrasion levels, highlighting the importance of achieving sufficient wear to optimise accuracy; increasing brushing temperature demonstrated increased enamel abrasion for silica and calcium carbonate systems, which may be related to slurry viscosities and particle suspension; varying brushing speed showed a small effect on abrasion of enamel at lower brushing speed, which may indicate the importance of maintenance of the abrasive in suspension. Adjusting key brushing variables significantly affected wear behaviour. The brushing simulator design provides a valuable model system for in vitro assessment of toothpaste abrasivity and the influence of variables in a controlled manner. Control of these variables will allow more reproducible study of in vitro tooth wear processes.

  15. The abrasive effect of commercial whitening toothpastes on eroded enamel.

    PubMed

    Mosquim, Victor; Martines Souza, Beatriz; Foratori Junior, Gerson Aparecido; Wang, Linda; Magalhães, Ana Carolina

    2017-06-01

    To evaluate the in vitro abrasive effect of commercial whitening toothpastes on eroded bovine enamel samples in respect to erosive tooth wear. 72 bovine crowns were embedded, polished and subjected to the baseline profile analysis. The samples were then protected in 2/3 of the enamel surface and were randomly assigned to six groups (n= 12/group): G1: Oral-B 3D White, G2: Close-up Diamond Attraction Power White, G3: Sorriso Xtreme White 4D, G4: Colgate Luminous White, G5: Crest (conventional toothpaste), G6:erosion only (control). All samples were submitted to an erosive pH cycling (4 x 90 seconds in 0.1% citric acid, pH 2.5, per day) and abrasive challenges (2 x 15 seconds, per day) for 7 days. After the first and the last daily cycles, the samples were subjected to abrasive challenges, using a toothbrushing machine, soft toothbrushes and slurry of the tested toothpastes (1.5 N). Between the challenges, the samples were immersed in artificial saliva. The final profile was obtained and overlaid to the baseline profile for the calculation of the erosive tooth wear (μm). The data were subjected to Kruskal-Wallis/Dunn tests (P< 0.05). G1 promoted the highest enamel wear (3.68±1.06 μm), similarly to G3 (3.17± 0.80 μm) and G4 (3.44± 1.29 μm). G3 and G4 performed similarly between them and compared with G5 (2.35± 1.44 μm). G2 (1.51± 0.95 μm) and G6 (0.85± 0.36 μm) showed the lowest enamel wear, which did not differ between them and from G5. Oral-B 3D White showed the highest abrasive potential while Close-up Diamond Attraction Power White showed the lowest abrasive potential on eroded enamel in vitro. This study showed that some commercial whitening toothpastes, especially those containing pyrophosphate associated with hydrated silica, enhanced enamel erosive wear.

  16. Abrasion resistant track shoe grouser

    DOEpatents

    Fischer, Keith D; Diekevers, Mark S; Afdahl, Curt D; Steiner, Kevin L; Barnes, Christopher A

    2013-04-23

    A track shoe for a track-type vehicle. The track shoe includes a base plate and a grouser projecting away from the base plate. A capping surface structure of substantially horseshoe shaped cross-section is disposed across a distal portion of the grouser. The capping surface structure covers portions of a distal edge surface and adjacent lateral surfaces. The capping surface structure is formed from an material characterized by enhanced wear resistance relative to portions of the grouser underlying the capping surface structure.

  17. Polishability and wear resistance of splint material for oral appliances produced with conventional, subtractive, and additive manufacturing.

    PubMed

    Huettig, Fabian; Kustermann, Achim; Kuscu, Ebru; Geis-Gerstorfer, Jürgen; Spintzyk, Sebastian

    2017-11-01

    Occlusal splints to treat bruxism are commonly made from polymethylmethacrylate (PMMA) in a manual workflow (powder-liquid technique). Today digitalization allows a machine-based manufacturing in subtractive (milling) and additive (printing) means using industrial-made PMMA or comparable resins. An in-vitro study should assess the surface finish and screen the wear resistance of conventional and industrial materials. Therefore, a total of 30 specimens made from conventionally PMMA (group C; powder-liquid, Palapress), polycarbonate ingots (group S; innoBlanc splint plus), and light-curing resin (group A; VarseoWax splint) were polished to examine the surface roughness (Ra) by profilometry and further analyzed by SEM. The specimens were loaded with a steatite ball moving 5000 times along 1cm with 5N of surface pressure under constant wetting (artificial saliva). The total height of profile (Pt) was calculated by further profilometry of the specimens. All specimen showed initially comparable Ra values ranging between 0.06 and 0.05µm (SD = 0.01) after polishing. SEM investigations revealed no visual cues for scratches or irregularities in any group. After abrasion test, the comparison of the wear depths, revealed mean Pt values of 111.4µm (SD = 18.5) in C, 85.7µm (SD = 21.5) in S, and 99.1µm (SD = 21.5) in A, whereas the mean of S was statistically different from C (p = 0.025). No signs of abrasion were found on the steatite balls. All materials showed comparable polished surfaces and a similar scale of wear. It remains questionable if the detected statistical differences are of clinical relevance, but indicates the need for tests of novel materials, especially in additive manufacturing. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. The role of the microfissuration of the rock matrix in the abrasion resistance of ornamental granitic rocks

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rey, Angel; Sanchez-Delgado, Nuria; Camino, Clara; Calleja, Lope; Ruiz de Argandoña, Vicente G.; Setien, Alexia

    2015-04-01

    The microcrack density and the abrasion resistance of five ornamental granites (Albero, Gris Alba, Mondariz, Rosa Porriño and Traspieles) from Galicia (NW Spain) have been quantified as part of a research aimed to interpret the cuttability of the rocks in relation to the petrophysical properties of the rock matrix. Large blocks from the quarries have been cut with an industrial saw and the microcrack density and the abrasion resistance have been measured in two surfaces: H, parallel to the cut surface; T, perpendicular both to the cut surface and the cutting direction. Both planes are perpendicular to the rift plane, as it is known in quarry works. The microcrack density has been quantified following an stereological procedure applied to polished sections imaged under scanning electron microscopy. The magnification of the images allowed the study of microcracks as narrow as 2 microns in aperture. The density has been quantified in terms of length of microcrack traces per surface unit so possible anisotropies of the microcrack network could be detected. The obtained values are in the typical range for this type of rocks although the Traspieles granite shows a higher value due to its weathering degree (H: 5.11, T: 5.37 mm/mm2). The values measured in the two surfaces (H and T) are quite similar in four of the rocks; only the Albero granite shows a marked anisotropy (H: 2.76 T: 3.53 mm/mm2). The abrasion resistance of the rocks has been measured following the european standard EN 14157:2004 using the capon method. The rocks can be classified in two groups according to their abrasion resistance. Rosa Porriño, Gris Alba and Mondariz granites are the more resistant to abrasion with values around 16-17 mm. Albero and Traspieles granites are less resistant with values higher than 19 mm. The results show a good correlation between the microcrack density and the abrasion resistance. As can be expected the rocks with high microcrack density show low abrasion resistance. The

  19. High Thermal Conductivity and High Wear Resistance Tool Steels for cost-effective Hot Stamping Tools

    NASA Astrophysics Data System (ADS)

    Valls, I.; Hamasaiid, A.; Padré, A.

    2017-09-01

    In hot stamping/press hardening, in addition to its shaping function, the tool controls the cycle time, the quality of the stamped components through determining the cooling rate of the stamped blank, the production costs and the feasibility frontier for stamping a given component. During the stamping, heat is extracted from the stamped blank and transported through the tool to the cooling medium in the cooling lines. Hence, the tools’ thermal properties determine the cooling rate of the blank, the heat transport mechanism, stamping times and temperature distribution. The tool’s surface resistance to adhesive and abrasive wear is also an important cost factor, as it determines the tool durability and maintenance costs. Wear is influenced by many tool material parameters, such as the microstructure, composition, hardness level and distribution of strengthening phases, as well as the tool’s working temperature. A decade ago, Rovalma developed a hot work tool steel for hot stamping that features a thermal conductivity of more than double that of any conventional hot work tool steel. Since that time, many complimentary grades have been developed in order to provide tailored material solutions as a function of the production volume, degree of blank cooling and wear resistance requirements, tool geometries, tool manufacturing method, type and thickness of the blank material, etc. Recently, Rovalma has developed a new generation of high thermal conductivity, high wear resistance tool steel grades that enable the manufacture of cost effective tools for hot stamping to increase process productivity and reduce tool manufacturing costs and lead times. Both of these novel grades feature high wear resistance and high thermal conductivity to enhance tool durability and cut cycle times in the production process of hot stamped components. Furthermore, one of these new grades reduces tool manufacturing costs through low tool material cost and hardening through readily

  20. Wear Characteristics of Ni-Based Hardfacing Alloy Deposited on Stainless Steel Substrate by Laser Cladding

    NASA Astrophysics Data System (ADS)

    Awasthi, Reena; Limaye, P. K.; Kumar, Santosh; Kushwaha, Ram P.; Viswanadham, C. S.; Srivastava, Dinesh; Soni, N. L.; Patel, R. J.; Dey, G. K.

    2015-03-01

    In this study, dry sliding wear characteristics of the Ni-based hardfacing alloy (Ni-Mo-Cr-Si) deposited on stainless steel SS316L substrate by laser cladding have been presented. Dry sliding wear behavior of the laser clad layer was evaluated against two different counter bodies, AISI 52100 chromium steel (~850 VHN) and tungsten carbide ball (~2200 VHN) to study both adhesive and abrasive wear characteristics, in comparison with the substrate SS316L using ball on plate reciprocating wear tester. The wear resistance was evaluated as a function of load and sliding speed for a constant sliding amplitude and sliding distance. The wear mechanisms were studied on the basis of wear surface morphology and microchemical analysis of the wear track using SEM-EDS. Laser clad layer of Ni-Mo-Cr-Si on SS316L exhibited much higher hardness (~700 VHN) than that of substrate SS316L (~200 VHN). The laser clad layer exhibited higher wear resistance as compared to SS316L substrate while sliding against both the counterparts. However, the improvement in the wear resistance of the clad layer as compared to the substrate was much higher while sliding against AISI 52100 chromium steel than that while sliding against WC, at the same contact stress intensity.

  1. The prevalence, aetiology and clinical appearance of tooth wear: the Nigerian experience.

    PubMed

    Oginni, O; Olusile, A O

    2002-08-01

    To establish the prevalence and severity of tooth wear among Nigerians and to compare the pattern and aetiology with findings of earlier studies in Western populations. Clinical examinations for tooth wear using the tooth wear index (TWI). The Federal Republic of Nigeria. Patients attending the Dental Hospital, Obafemi Awolowo University Teaching Hospital's Complex Ile-Ife. Attrition, abrasion and erosion. Of the 126 patients with tooth wear 81 had attrition, 20 had abrasion, 9 had erosion and 16 had attrition and abrasion combined. A total of 15,480 tooth surfaces were examined. 2,229 (14.4%) surfaces had tooth wear out of which 1,007 (6.5%) were pathologically worn down. The frequency of tooth wear increased with the age of patients. Most of the pathologically worn surfaces were just one point above maximum acceptable value. The aetiological factors associated with tooth wear are not different from those encountered in Western cultures but the pattern of wear differs. Pathological tooth wear presents as an age related phenomenon and is probably more severe in Nigerians.

  2. Elucidation of wear mechanisms by ferrographic analysis

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.

    1981-01-01

    The use of ferrographic analysis in conjunction with light and scanning electron microscopy is described for the elucidation of wear mechanisms taking place in operating equipment. Example of adhesive wear, abrasive wear, corrosive wear, rolling element fatigue, lubricant breakdown, and other wear modes are illustrated. In addition, the use of magnetic solutions to precipitate nonmagnetic debris from aqueous and nonaqueous fluids is described.

  3. Corrosion and wear properties of Zn-Ni and Zn-Ni-Al2O3 multilayer electrodeposited coatings

    NASA Astrophysics Data System (ADS)

    Shourgeshty, M.; Aliofkhazraei, M.; Karimzadeh, A.; Poursalehi, R.

    2017-09-01

    Zn-Ni and Zn-Ni-Al2O3 multilayer coatings with 32, 128, and 512 layers were electroplated on a low carbon steel substrate by pulse electrodeposition under alternative changes in the duty cycle between 20% and 90% and a constant frequency of 250 Hz. Corrosion behavior was investigated by potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) and wear behavior of the coatings was evaluated by a pin on disk test. The results showed that the corrosion resistance of coatings was improved by increasing the number of layers (the decrease in layer thickness) as well as the presence of alumina nanoparticles. The lowest corrosion current density corresponds to Zn-Ni-Al2O3 with 512 layers equal to 3.74 µA cm-2. Increasing the number of layers in the same total thickness and the presence of alumina nanoparticles within the coating also leads to the improvement in wear resistance of the samples. The coefficient of friction decreased with increasing number of layers and the lowest coefficient of friction (0.517) corresponds to Zn-Ni-Al2O3 coating with 512 layers. Wear mechanism of Zn-Ni coatings with a different number of layers is adhesive while in the Zn-Ni-Al2O3 coatings wear mechanism is a combination of adhesive and abrasive wear, where by increasing the number of the layers to 512 abrasive wear mechanism becomes dominant.

  4. Development of a wear-resistant flux cored wire of Fe-C-Si-Mn-Cr-Ni-Mo-V system for deposit welding of mining equipment parts

    NASA Astrophysics Data System (ADS)

    Osetkovsky, I. V.; Kozyrev, N. A.; Kryukov, R. E.; Usoltsev, A. A.; Gusev, A. I.

    2017-09-01

    The effect of introduction of cobalt in the charge of the flux cored wire of Fe-C-Si-Mn-Cr-Ni-Mo-V system operating under abrasive and abrasive-shock loads is studied. In the laboratory conditions samples of flux cored wires were made, deposition was performed, the effect of cobalt on the hardness and the degree of wear was evaluated, metallographic studies were carried out. The influence of cobalt introduced into the charge of the flux cored wire of Fe-C-Si-Mn-Cr-Ni-Mo-V system on the structure, nature of nonmetallic inclusions, hardness and wear resistance of the weld metal was studied. In the laboratory conditions samples flux cored wire were made using appropriate powdered materials. As a carbon-fluorine-containing material dust from gas cleaning units of aluminum production was used. In the course of the study the chemical composition of the weld metal was determined, metallographic analysis was performed, mechanical properties were determined. As a result of the metallographic analysis the size of the former austenite grain, martensite dispersion in the structure of the weld metal, the level of contamination with its nonmetallic inclusions were established.

  5. Tribological behaviour of orthodontic archwires under dry and wet sliding conditions in-vitro. II--Wear patterns.

    PubMed

    Berradja, Abdenacer; Willems, Guy; Celis, Jean-Pierre

    2006-05-01

    To evaluate the wear patterns of orthodontic archwires in dry and wet conditions in-vitro. The patterns of wear of stainless steel and NiTi orthodontic archwires were investigated with a fretting wear tribometer fitted with an alumina ball. The tribometer was operated at 23 degrees C in three different environments: ambient air with 50 per cent relative humidity (RH), 0.9 wt. per cent sodium chloride solution and deionised water. Differences in the wear characteristics of the archwires were investigated by scanning electron microscopy. Energy Dispersive X-ray Analysis and Inductively Coupled Plasma Analysis were used to investigate the surface composition of the wires, the wear debris generated during fretting and the corrosion products in the test solutions. Both archwire materials were degraded by oxidational wear in ambient air. The NiTi wires were more resistant to wear than the stainless steel wires. In the aqueous media the stainless steel wires were degraded by abrasive wear, while the NiTi wires were degraded by adhesive wear. In ambient air with 50 per cent RH, NiTi wires were more resistant to wear than stainless steel wires. Both archwire materials exhibited higher wear rates in the solutions than in air, indicating some synergism between the wear and corrosion processes. In the solutions the stainless steel archwires had a much lower corrosion-wear resistance than the NiTi archwires.

  6. Computational Fluid Dynamic Simulation of Flow in Abrasive Water Jet Machining

    NASA Astrophysics Data System (ADS)

    Venugopal, S.; Sathish, S.; Jothi Prakash, V. M.; Gopalakrishnan, T.

    2017-03-01

    Abrasive water jet cutting is one of the most recently developed non-traditional manufacturing technologies. In this machining, the abrasives are mixed with suspended liquid to form semi liquid mixture. The general nature of flow through the machining, results in fleeting wear of the nozzle which decrease the cutting performance. The inlet pressure of the abrasive water suspension has main effect on the major destruction characteristics of the inner surface of the nozzle. The aim of the project is to analyze the effect of inlet pressure on wall shear and exit kinetic energy. The analysis could be carried out by changing the taper angle of the nozzle, so as to obtain optimized process parameters for minimum nozzle wear. The two phase flow analysis would be carried by using computational fluid dynamics tool CFX. It is also used to analyze the flow characteristics of abrasive water jet machining on the inner surface of the nozzle. The availability of optimized process parameters of abrasive water jet machining (AWJM) is limited to water and experimental test can be cost prohibitive. In this case, Computational fluid dynamics analysis would provide better results.

  7. Filler features and their effects on wear and degree of conversion of particulate dental resin composites.

    PubMed

    Turssi, C P; Ferracane, J L; Vogel, K

    2005-08-01

    Based on the incomplete understanding on how filler features influence the wear resistance and monomer conversion of resin composites, this study sought to evaluate whether materials containing different shapes and combinations of size of filler particles would perform similarly in terms of three-body abrasion and degree of conversion. Twelve experimental monomodal, bimodal or trimodal composites containing either spherical or irregular shaped fillers ranging from 100 to 1500 nm were examined. Wear testings were conducted in the OHSU wear machine (n = 6) and quantified after 10(5) cycles using a profilometer. Degree of conversion (DC) was measured by FTIR spectrometry at the surface of the composites (n = 6). Data sets were analyzed using one-way Anova and Tukey's test at a significance level of 0.05. Filler size and geometry was found to have a significant effect on wear resistance and DC of composites. At specific sizes and combinations, the presence of small filler particles, either spherical or irregular, may aid in enhancing the wear resistance of composites, without compromising the percentage of reacted carbon double bonds.

  8. Etude de la degradation des refractaires aluminosiliceux par abrasion, chocs thermiques et corrosion par l'aluminium: Correlation et interaction des mecanismes

    NASA Astrophysics Data System (ADS)

    Ntakaburimvo, Nicodeme

    Aluminosilicate refractories used for melting and holding furnaces on which the present work was focused are submitted to mechanical abuse such as abrasion, mechanical impact and erosion, on one hand; and to chemical degradation by corrosion, as well as to thermal stresses, mostly due to thermal shocks; on the other hand. This thesis is focused on four main objectives. The first one is related to the designing of an experimental set-up allowing abrasion testing of refractories. The second deals with the separate study of the deterioration of aluminosilicate refractories by abrasion, thermal shock and corrosion. The third is the correlation between these three mechanisms while the fourth is related to the interaction between thermal shock and corrosion. One of the contributions of this thesis is the realisation of the above mentioned experimental set-up, which permits to carry out refractories abrasion testing, as well as at room and high temperature, in the absence or in the presence of molten metal. The fact of testing refractory resistance when it is submitted separately and simultaneously to the action of dynamic corrosion, erosion and abrasion leads to the studying of the influence of each of these three mechanisms on the other. One of the characteristics of the designed set-up is the fact that it allows to adjust the seventy testing conditions according to the mechanical resistance of the test material. The other important point is related to the fact the abrasion tests were carried out in such manner to permit degradation quantification, otherwise than by the traditional method of loss of weight measurement; particularly by measuring the wear depth and the residual material properties, such as the rupture force and the strength. A perfect correlation was observed between the wear depth and the loss of weight, both being negatively correlated with the residual rupture force. The abrasion resistance was found to be globally positively correlated with the

  9. Three-body wear of resin denture teeth with and without nanofillers.

    PubMed

    Stober, Thomas; Henninger, Moritz; Schmitter, Marc; Pritsch, Maria; Rammelsberg, Peter

    2010-02-01

    The wear behavior of newly developed denture teeth with nanofillers may be different from teeth with other chemical formulations. The purpose of this study was to examine the 3-body wear resistance of 11 different commercially available resin denture teeth. The materials tested were conventional (SR Orthotyp PE, Orthognath) and cross-linked acrylic resin teeth without inorganic fillers (Premium 8, SR Postaris DCL, Trubyte Portrait, Artiplus), composite resin teeth with inorganic fillers (SR Orthosit PE, Vitapan), and composite resin teeth (experimental materials) with inorganic nanofillers (NC Veracia Posterior, e-Ha, Mondial). Human enamel and a ceramic denture tooth (Lumin Vacuum) were used as reference materials. The 3-body wear test was performed in a wear machine developed by the Academic Center for Dentistry Amsterdam (ACTA), with millet suspension acting as an abrasive medium (n=10, test load: 15 N, slip rate: 20%, number of cycles: 100,000). Wear was determined with the aid of a profilometer. Data were analyzed with the Kruskal-Wallis test and Mann-Whitney U test using the closed testing approach (significance level for familywise error rate, alpha=.05). None of the acrylic and composite resin materials tested in this study demonstrated the 3-body wear resistance of ceramic teeth or human enamel. Teeth with inorganic fillers demonstrated significantly lower wear values than conventional or cross-linked acrylic resin teeth without fillers. Composite resin teeth with traditional fillers showed significantly lower wear than composite resin teeth with nanofillers. Denture teeth with and without inorganic fillers differed significantly with regard to the degree of wear generated in the ACTA wear simulator. The incorporation of nanofillers did not improve the wear resistance compared to teeth with traditional fillers.

  10. Detecting Inter-Cusp and Inter-Tooth Wear Patterns in Rhinocerotids

    PubMed Central

    Taylor, Lucy A.; Kaiser, Thomas M.; Schwitzer, Christoph; Müller, Dennis W. H.; Codron, Daryl; Clauss, Marcus; Schulz, Ellen

    2013-01-01

    Extant rhinos are the largest extant herbivores exhibiting dietary specialisations for both browse and grass. However, the adaptive value of the wear-induced tooth morphology in rhinos has not been widely studied, and data on individual cusp and tooth positions have rarely been published. We evaluated upper cheek dentition of browsing Diceros bicornis and Rhinoceros sondaicus, mixed-feeding R. unicornis and grazing Ceratotherium simum using an extended mesowear method adapted for rhinos. We included single cusp scoring (EM(R)-S) to investigate inter-cusp and inter-tooth wear patterns. In accordance with previous reports, general mesowear patterns in D. bicornis and R. sondaicus were attrition-dominated and C. simum abrasion-dominated, reflecting their respective diets. Mesowear patterns for R. unicornis were more attrition-dominated than anticipated by the grass-dominated diet, which may indicate a low intake of environmental abrasives. EM(R)-S increased differentiation power compared to classical mesowear, with significant inter-cusp and inter-tooth differences detected. In D. bicornis, the anterior cusp was consistently more abrasion-dominated than the posterior. Wear differences in cusp position may relate to morphological adaptations to dietary regimes. Heterogeneous occlusal surfaces may facilitate the comminution of heterogeneous browse, whereas uniform, broad grinding surfaces may enhance the comminution of physically more homogeneous grass. A negative tooth wear gradient was found in D. bicornis, R. sondaicus and R. unicornis, with wear patterns becoming less abrasion-dominated from premolars to molars. No such gradients were evident in C. simum which displayed a uniform wear pattern. In browsers, premolars may be exposed to higher relative grit loads, which may result in the development of wear gradients. The second premolar may also have a role in food cropping. In grazers, high absolute amounts of ingested abrasives may override other signals, leading to

  11. Detecting inter-cusp and inter-tooth wear patterns in rhinocerotids.

    PubMed

    Taylor, Lucy A; Kaiser, Thomas M; Schwitzer, Christoph; Müller, Dennis W H; Codron, Daryl; Clauss, Marcus; Schulz, Ellen

    2013-01-01

    Extant rhinos are the largest extant herbivores exhibiting dietary specialisations for both browse and grass. However, the adaptive value of the wear-induced tooth morphology in rhinos has not been widely studied, and data on individual cusp and tooth positions have rarely been published. We evaluated upper cheek dentition of browsing Diceros bicornis and Rhinoceros sondaicus, mixed-feeding R. unicornis and grazing Ceratotherium simum using an extended mesowear method adapted for rhinos. We included single cusp scoring (EM(R)-S) to investigate inter-cusp and inter-tooth wear patterns. In accordance with previous reports, general mesowear patterns in D. bicornis and R. sondaicus were attrition-dominated and C. simum abrasion-dominated, reflecting their respective diets. Mesowear patterns for R. unicornis were more attrition-dominated than anticipated by the grass-dominated diet, which may indicate a low intake of environmental abrasives. EM(R)-S increased differentiation power compared to classical mesowear, with significant inter-cusp and inter-tooth differences detected. In D. bicornis, the anterior cusp was consistently more abrasion-dominated than the posterior. Wear differences in cusp position may relate to morphological adaptations to dietary regimes. Heterogeneous occlusal surfaces may facilitate the comminution of heterogeneous browse, whereas uniform, broad grinding surfaces may enhance the comminution of physically more homogeneous grass. A negative tooth wear gradient was found in D. bicornis, R. sondaicus and R. unicornis, with wear patterns becoming less abrasion-dominated from premolars to molars. No such gradients were evident in C. simum which displayed a uniform wear pattern. In browsers, premolars may be exposed to higher relative grit loads, which may result in the development of wear gradients. The second premolar may also have a role in food cropping. In grazers, high absolute amounts of ingested abrasives may override other signals, leading to

  12. Plasma deposition and surface modification techniques for wear resistance

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1982-01-01

    The ion-assisted or plasma coating technology is discussed as it applies to the deposition of hard, wear resistant refractory compound films. Of the many sputtering and ion plating modes and configurations the reactive magnetron sputtering and the reactive triode ion plating techniques are the preferred ones to deposit wear resistant coatings for tribological applications. Both of these techniques incorporate additional means to enhance the ionization efficiency and chemical reaction to precision tailor desirable tribological characteristics. Interrelationships between film formation, structure, and ribological properties are strictly controlled by the deposition parameters and the substrate condition. The enhanced ionization contributes to the excellent adherence and coherence, reduced internal stresses and improved structural growth to form dense, cohesive, equiaxed grain structure for improved wear resistance and control.

  13. Dry sliding wear behavior of Al 2219/SiCp-Gr hybrid metal matrix composites

    NASA Astrophysics Data System (ADS)

    Basavarajappa, S.; Chandramohan, G.; Mukund, K.; Ashwin, M.; Prabu, M.

    2006-12-01

    The dry sliding wear behavior of Al 2219 alloy and Al 2219/SiCp/Gr hybrid composites are investigated under similar conditions. The composites are fabricated using the liquid metallurgy technique. The dry sliding wear test is carried out for sliding speeds up to 6 m/s and for normal loads up to 60 N using a pin on disc apparatus. It is found that the addition of SiCp and graphite reinforcements increases the wear resistance of the composites. The wear rate decreases with the increase in SiCp reinforcement content. As speed increases, the wear rate decreases initially and then increases. The wear rate increases with the increase in load. Scanning electron microscopy micrographs of the worn surface are used to predict the nature of the wear mechanism. Abrasion is the principle wear mechanism for the composites at low sliding speeds and loads. At higher loads, the wear mechanism changes to delamination.

  14. [Effect of surface modification using laser on wear resistance of titanium].

    PubMed

    Sato, Yohei

    2005-02-01

    Severe wear of cast commercial pure (CP) titanium teeth was observed in a clinical survey. This study evaluated the wear resistance of cast CP titanium and titanium alloy teeth after the surface was modified using laser technology. Teeth patterns were duplicated from artificial first molars (Livdent FB30, GC, Japan). All teeth specimens were cast with CP Ti grade 3 (T-Alloy H, GC) and Ti-6Al-7Nb (T-Alloy Tough, GC). After the occlusal surface was blasted with Al(2)O(3), the occlusal contact points were modified using a laser (Neo laser L, Girrbach, Germany) at the following irradiation conditions (voltage: 260 V; pulse: 7 ms; focus: 1.5 mm). These parameters were determined by preliminary study. As a control, Type IV gold alloy (PGA-3, Ishifuku, Japan) was also cast conventionally. Both maxillary and mandibular teeth were worn using an in vitro two-body wear testing apparatus that simulated chewing function (60 strokes/min; grinding distance: 2 mm under flowing water). Wear resistance was assessed as volume loss (mm(3)) at 5 kgf (grinding force) after 50,000 strokes. The results (n=5) were analyzed by ANOVA/Scheffé's test (alpha=0.05). The gold alloy showed the best wear resistance of all the metals tested. Of all the titanium specimens tested, the modified surface indicated significantly greater wear resistance than did conventional titanium teeth without surface modification (p<0.05). Wear resistance was increased by modification of the surface using a laser. If severe wear of titanium teeth was observed clinically, little wear occurred when the occlusal facets were irradiated using a laser.

  15. Abrasion Testing of Candidate Outer Layer Fabrics for Lunar EVA Space Suits

    NASA Technical Reports Server (NTRS)

    Mitchell, Kathryn

    2009-01-01

    During the Apollo program, the space suit outer layer fabrics were severely abraded after just a few Extravehicular Activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots, which penetrated the outer layer fabric into the thermal protection layers after less than eight hours of surface operations. Current plans for the Constellation Space Suit Element require the space suits to support hundreds of hours of EVA on the Lunar surface, creating a challenge for space suit designers to utilize materials advances made over the last forty years and improve upon the space suit fabrics used in the Apollo program. A test methodology has been developed by the NASA Johnson Space Center Crew and Thermal Systems Division for establishing comparative abrasion wear characteristics between various candidate space suit outer layer fabrics. The abrasion test method incorporates a large rotary drum tumbler with rocks and loose lunar simulant material to induce abrasion in fabric test cylinder elements, representative of what might occur during long term planetary surface EVAs. Preliminary materials screening activities were conducted to determine the degree of wear on representative space suit outer layer materials and the corresponding dust permeation encountered between subsequent sub-layers of thermal protective materials when exposed to a simulated worst case eight hour EVA. The test method was used to provide a preliminary evaluation of four candidate outer layer fabrics for future planetary surface space suit applications. This paper provides a review of previous abrasion studies on space suit fabrics, details the methodologies used for abrasion testing in this particular study, shares the results of the testing, and provides recommendations for future work.

  16. Abrasion Testing of Candidate Outer Layer Fabrics for Lunar EVA Space Suits

    NASA Technical Reports Server (NTRS)

    Mitchell, Kathryn C.

    2010-01-01

    During the Apollo program, the space suit outer layer fabrics were badly abraded after just a few Extravehicular Activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots, which penetrated the outer layer fabric into the thermal protection layers after less than eight hours of surface operations. Current plans for the Constellation Space Suit Element require the space suits to support hundreds of hours of EVA on the Lunar surface, creating a challenge for space suit designers to utilize materials advances made over the last forty years and improve upon the space suit fabrics used in the Apollo program. A test methodology has been developed by the NASA Johnson Space Center Crew and Thermal Systems Division for establishing comparative abrasion wear characteristics between various candidate space suit outer layer fabrics. The abrasion test method incorporates a large rotary drum tumbler with rocks and loose lunar simulant material to induce abrasion in fabric test cylinder elements, representative of what might occur during long term planetary surface EVAs. Preliminary materials screening activities were conducted to determine the degree of wear on representative space suit outer layer materials and the corresponding dust permeation encountered between subsequent sub -layers of thermal protective materials when exposed to a simulated worst case eight hour EVA. The test method was used to provide a preliminary evaluation of four candidate outer layer fabrics for future planetary surface space suit applications. This Paper provides a review of previous abrasion studies on space suit fabrics, details the methodologies used for abrasion testing in this particular study, and shares the results and conclusions of the testing.

  17. Mars Pathfinder: The Wheel Abrasion Experiment

    NASA Technical Reports Server (NTRS)

    1996-01-01

    NASA Lewis Research Center's Wheel Abrasion Experiment (WAE) will measure the amount of wear on wheel surfaces of the Mars Pathfinder rover. WAE uses thin films of Al, Ni, and Pt (ranging in thickness from 200 to 1000 angstroms) deposited on black, anodized Al strips attached to the rover wheel. As the wheel moves across the martian surface, changes in film reflectivity will be monitored by reflected sunlight. These changes, measured as output from a special photodetector mounted on the rover chassis, will be due to abrasion of the metal films by martian surface sand, dust, and clay.

  18. Abrasive Endoprosthetic Wear Particles Inhibit IFN-γ Secretion in Human Monocytes Via Upregulating TNF-α-Induced miR-29b.

    PubMed

    Bu, Yan-Min; Zheng, De-Zhi; Wang, Lei; Liu, Jun

    2017-02-01

    The adverse biological responses to prostheses wear particles commonly led to the failure of total hip arthroplasty. Among the released cytokines, interferon-γ (IFN-γ) has been found to be a critical functional factor during osteoclast differentiation. However, the molecular mechanism underlying the regulation of IFN-γ in wear particles-induced cells still needs to be determined. Four kinds of abrasive endoprosthetic wear particle were used to treat THP-1 cells, including polymethylmethacrylate (PMMA), zirconiumoxide (ZrO 2 ), commercially pure titanium (cpTi), and titanium alloy (Ti-6Al-7Nb), with a concentration of 0.01, 0.05, 0.1, or 0.2 mg/ml for 48 h. The expression of IFN-γ and miR-29b was detected by real-time RT-PCR or ELISA. Luciferase reporter assay was performed to determine the regulation of miR-29b on IFN-γ. The effect of miR-29b inhibitor on the expression of wear particle-induced IFN-γ was detected. The expression of miR-29b was examined in THP-1 cells treated with tumor necrosis factor-alpha (TNF-α). The expression of IFN-γ was downregulated and the level of miR-29b was increased in THP-1 cells pretreated with wear particles. IFN-γ was a target of miR-29b. Wear particles inhibited the expression of IFN-γ through miR-29b. The expression of miR-29b was significantly reduced in THP-1 cells treated with TNF-α neutralizing antibody and particles comparing to that in the cells treated with particles alone. Wear particles inhibit the IFN-γ secretion in human monocytes, which was associated with the upregulating TNF-α-induced miR-29b.

  19. Wear resistance of polypropylene-SiC composite

    NASA Astrophysics Data System (ADS)

    Abenojar, J.; Enciso, B.; Martínez, MA; Velasco, F.

    2017-05-01

    In this work, the wear resistance of thermoplastic composites with a high amount of ceramic is evaluated. Composites made of polypropylene (PP) and silicon carbide (SiC) powder at 50 wt% were used with the final objective of manufacturing ablative materials. This is the first part of a project studying the wear resistance and the mechanical properties of those composites, to be used in applications like habitat industry. In theory, the exposure to high temperature of ablative materials involves the elimination of thermal energy by the sacrifice of surface polymer. In our case, PP will act as a heat sink, up to the reaction temperature (melting or sublimation), where endothermic chemical decomposition into charred material and gaseous products occurs. As the surface is eroded, it is formed a SiC like-foam with improved insulation performance. Composites were produced by extrusion and hot compression. The wear characterization was performed by pin-on-disk test. Wear test was carried out under standard ASTM G99. The parameters were 120 rpm speed, 15 N load, a alumina ball with 6 mm as pin and 1000 m sliding distance. The tracks were also observed by opto-digital microscope.

  20. Wear Resistance Properties Reinforcement Using Nano-Al/Cu Composite Coating in Sliding Bearing Maintenance.

    PubMed

    Liu, Hongtao; Li, Zhixiong; Wang, Jianmei; Sheng, Chenxing; Liu, Wanli

    2018-03-01

    Sliding bearing maintenance is crucial for reducing the cost and extending the service life. An efficient and practical solution is to coat a restorative agent onto the worn/damaged bearings. Traditional pure-copper (Cu) coating results in a soft surface and poor abrasion resistance. To address this issue, this paper presents a nano-composite repairing coating method. A series of nano-Al/Cu coatings were prepared on the surface of 45 steel by composite electro-brush plating (EBP). Their micro-hardness was examined by a MHV-2000 Vickers hardness tester, and tribological properties by a UMT-2M Micro-friction tester, 3D profiler and SEM. Then, the influence of processing parameters such as nano-particle concentration and coating thickness on the micro-hardness of nano-Al/Cu coating was analyzed. The experimental analysis results demonstrate that, when the nano-Al particle concentration in electrolyte was 10 g/L, the micro-hardness of the composite coating was 1.1 times as much as that of pure-Cu coating. When the Al nano-particle concentration in electrolyte was 20 g/L, the micro-hardness of the composite coating reached its maximum value (i.e., 231.6 HV). Compared with the pure-Cu coating, the hardness and wear resistance of the nano-composite coating were increased, and the friction coefficient and wear volume were decreased, because of the grain strengthening and dispersion strengthening. The development in this work may provide a feasible and effective nano-composite EBP method for sliding bearing repair.

  1. Wear-Resistant, Self-Lubricating Surfaces of Diamond Coatings

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1995-01-01

    In humid air and dry nitrogen, as-deposited, fine-grain diamond films and polished, coarse-grain diamond films have low steady-state coefficients of friction (less than 0.1) and low wear rates (less than or equal to 10(exp -6) mm(exp 3)/N-m). In an ultrahigh vacuum (10(exp -7) Pa), however, they have high steady-state coefficients of friction (greater than 0.6) and high wear rates (greater than or equal to 10(exp -4) mm(exp 3)/N-m). Therefore, the use of as-deposited, fine-grain and polished, coarse-grain diamond films as wear-resistant, self-lubricating coatings must be limited to normal air or gaseous environments such as dry nitrogen. On the other hand, carbon-ion-implanted, fine-grain diamond films and nitrogen-ion-implanted, coarse-grain diamond films have low steady-state coefficients of friction (less than 0.1) and low wear rates (less than or equal to 10(exp -6) mm(exp 3)/N-m) in all three environments. These films can be effectively used as wear-resistant, self-lubricating coatings in an ultrahigh vacuum as well as in normal air and dry nitrogen.

  2. Computational Fluid Dynamics Analysis of Nozzle in Abrasive Water Jet Machining

    NASA Astrophysics Data System (ADS)

    Venugopal, S.; Chandresekaran, M.; Muthuraman, V.; Sathish, S.

    2017-03-01

    Abrasive water jet cutting is one of the most recently developed non-traditional manufacturing technologies. The general nature of flow through the machining, results in rapid wear of the nozzle which decrease the cutting performance. It is well known that the inlet pressure of the abrasive water suspension has main effect on the erosion characteristics of the inner surface of the nozzle. The objective of the project is to analyze the effect of inlet pressure on wall shear and exit kinetic energy. The analysis would be carried out by varying the inlet pressure of the nozzle, so as to obtain optimized process parameters for minimum nozzle wear. The two phase flow analysis would be carried by using computational fluid dynamics tool CFX. The availability of minimized process parameters such as of abrasive water jet machining (AWJM) is limited to water and experimental test can be cost prohibitive.

  3. Surface Design and Engineering Toward Wear-Resistant, Self-Lubricating Diamond Films and Coatings

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1999-01-01

    The tribological properties of chemical-vapor-deposited (CVD) diamond films vary with the environment, possessing a Jekyll-and-Hyde character. CVD diamond has low coefficient of friction and high wear resistance in air but high coefficient of friction and low wear resistance in vacuum. Improving the tribological functionality of materials (such as achieving low friction and good wear resistance) was an aim of this investigation. Three studies on the surface design, surface engineering, and tribology of CVD diamond have shown that its friction and wear are significantly reduced in ultrahigh vacuum. The main criteria for judging whether diamond films are an effective wear-resistant, self-lubricating material were coefficient of friction and wear rate, which must be less than 0.1 and on the order of 10(exp 6) cu mm/N(dot)m, respectively. In the first study the presence of a thin film (less than 1 micron thick) of amorphous, nondiamond carbon (hydrogenated carbon, also called diamondlike carbon or DLC) on CVD diamond greatly decreased the coefficient of friction and the wear rate. Therefore, a thin DLC film on CVD diamond can be an effective wear-resistant, lubricating coating in ultrahigh vacuum. In the second study the presence of an amorphous, nondiamond carbon surface layer formed on CVD diamond by ion implantation significantly reduced the coefficient of friction and the wear rate in ultrahigh vacuum. Therefore, such surface layers are acceptable for effective self-lubricating, wear-resistant applications of CVD diamond. In the third study CVD diamond in contact with cubic boron nitride exhibited low coefficient of friction in ultra high vacuum. Therefore, this materials combination can provide an effective self-lubricating, wear-resistant couple in ultrahigh vacuum.

  4. Heat sealable, flame and abrasion resistant coated fabric

    NASA Technical Reports Server (NTRS)

    Tschirch, R. P.; Sidman, K. R. (Inventor)

    1983-01-01

    Flame retardant, abrasion resistant elastomeric compositions are disclosed which are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Heat sealable coated fabrics employing such elastomeric compositions as coating film are produced by dissolving the elastomeric composition to form a solution, casting the solution onto a release paper and drying it to form an elastomeric film. The film is then bonded to a woven, knitted, or felted fabric.

  5. Understanding wear in dentistry.

    PubMed

    Mair, L H

    1999-01-01

    Tooth wear is an increasing problem in dentistry. Traditionally, it has been divided into three categories: abrasion, attrition, and erosion. However, most clinical cases of tooth wear involve more than one of these processes. It is often easier to make a diagnosis by looking for the signs of the fundamental wear processes rather than trying to categorize the individual case. Wear can be caused by direct surface-to-surface wear, an intervening slurry, or a corrosive environment. Wear occurs during mastication, but also at other times, often at night. Although it may be possible to institute a preventive regimen, this will not always help the patient if his or her prime concern is esthetics. The same processes that cause tooth wear will cause wear to restorative materials. To diagnose and prevent wear, its processes must be understood.

  6. Abrasion resistance of muscovite in aeolian and subaqueous transport experiments

    NASA Astrophysics Data System (ADS)

    Anderson, Calvin J.; Struble, Alexander; Whitmore, John H.

    2017-02-01

    Complementary aeolian and subaqueous transport experiments showed a trend in muscovite abrasion that may be useful for identifying ancient sandstones as aeolian or subaqueous in origin. We found that our experimental aeolian processes pulverized the micas quickly, while our subaqueous processes did not. In a pair of abrasion resistance experiments conducted with micaceous quartz sand, it was found that large muscovite grains were (1) reduced by aeolian processes to less than 500 μm in just 4 days, and (2) preserved by subaqueous processes to 610 ± 90 μm even after 356 days. At 20 days of aeolian transport no loose micas could be found even under the microscope, but after a year of subaqueous transport loose muscovite grains could still be seen with the naked eye. Thus, the occurrence and character of micas in a sandstone, particularly muscovite, may be helpful in determining the ancient depositional process.

  7. Corrosion and Wear Behaviors of Cr-Doped Diamond-Like Carbon Coatings

    NASA Astrophysics Data System (ADS)

    Viswanathan, S.; Mohan, L.; Bera, Parthasarathi; Kumar, V. Praveen; Barshilia, Harish C.; Anandan, C.

    2017-08-01

    A combination of plasma-enhanced chemical vapor deposition and magnetron sputtering techniques has been employed to deposit chromium-doped diamond-like carbon (DLC) coatings on stainless steel, silicon and glass substrates. The concentrations of Cr in the coatings are varied by changing the parameters of the bipolar pulsed power supply and the argon/acetylene gas composition. The coatings have been studied for composition, morphology, surface nature, nanohardness, corrosion resistance and wear resistance properties. The changes in I D / I G ratio with Cr concentrations have been obtained from Raman spectroscopy studies. Ratio decreases with an increase in Cr concentration, and it has been found to increase at higher Cr concentration, indicating the disorder in the coating. Carbide is formed in Cr-doped DLC coatings as observed from XPS studies. There is a decrease in sp 3/ sp 2 ratios with an increase in Cr concentration, and it increases again at higher Cr concentration. Nanohardness studies show no clear dependence of hardness on Cr concentration. DLC coatings with lower Cr contents have demonstrated better corrosion resistance with better passive behavior in 3.5% NaCl solution, and corrosion potential is observed to move toward nobler (more positive) values. A low coefficient of friction (0.15) at different loads is observed from reciprocating wear studies. Lower wear volume is found at all loads on the Cr-doped DLC coatings. Wear mechanism changes from abrasive wear on the substrate to adhesive wear on the coating.

  8. Study of wear mechanism of chopped fiber reinforced epoxy composite filled with graphite and bronze

    NASA Astrophysics Data System (ADS)

    Patil, Nitinchand; Prasad, Krishna

    2018-04-01

    The combined effect of graphite and sintered bronze with a short glass fiber reinforced epoxy composites was investigated in this work. A pin on disc wear test was carried out to study the wear behaviour and mechanism of the composites. The objective of this work is to develop an alternate friction resistance material for the application of sliding bearing. It was observed that the addition of sintered bronze improved mechanical and thermal stability of the composites as bronze has low contact resistance with graphite and has high thermal conductivity. It was observed from the test results that increased volume percentage of graphite and presence of bronze are play significant role in wear mechanism of the composites. It was observed from the scanning electronic microscopes (SEM) that the abrasive and adhesive wear mechanism was prominent in this study. It was also evident from the result that the frictional force remains stable irrespective of the applied normal load.

  9. Three-Body Abrasion Testing Using Lunar Dust Simulants to Evaluate Surface System Materials

    NASA Technical Reports Server (NTRS)

    Kobrick, Ryan L.; Budinski, Kenneth G.; Street, Kenneth W., Jr.; Klaus, David M.

    2010-01-01

    Numerous unexpected operational issues relating to the abrasive nature of lunar dust, such as scratched visors and spacesuit pressure seal leaks, were encountered during the Apollo missions. To avoid reoccurrence of these unexpected detrimental equipment problems on future missions to the Moon, a series of two- and three-body abrasion tests were developed and conducted in order to begin rigorously characterizing the effect of lunar dust abrasiveness on candidate surface system materials. Two-body scratch tests were initially performed to examine fundamental interactions of a single particle on a flat surface. These simple and robust tests were used to establish standardized measurement techniques for quantifying controlled volumetric wear. Subsequent efforts described in the paper involved three-body abrasion testing designed to be more representative of actual lunar interactions. For these tests, a new tribotester was developed to expose samples to a variety of industrial abrasives and lunar simulants. The work discussed in this paper describes the three-body hardware setup consisting of a rotating rubber wheel that applies a load on a specimen as a loose abrasive is fed into the system. The test methodology is based on ASTM International (ASTM) B611, except it does not mix water with the abrasive. All tests were run under identical conditions. Abraded material specimens included poly(methyl methacrylate) (PMMA), hardened 1045 steel, 6061-T6 aluminum (Al) and 1018 steel. Abrasives included lunar mare simulant JSC- 1A-F (nominal size distribution), sieved JSC-1A-F (<25 m particle diameter), lunar highland simulant NU-LHT-2M, alumina (average diameter of 50 m used per ASTM G76), and silica (50/70 mesh used per ASTM G65). The measured mass loss from each specimen was converted using standard densities to determine total wear volume in cm3. Abrasion was dominated by the alumina and the simulants were only similar to the silica (i.e., sand) on the softer materials of

  10. A comparison of the tribological behaviour of Y-TZP in tea and coffee under micro-abrasion conditions

    NASA Astrophysics Data System (ADS)

    Sharifi, S.; Stack, M. M.

    2013-10-01

    The micro-abrasion of Y-TZP, a candidate dental restorative material, was investigated in a range of caffeine-containing solutions which included tea and coffee. Additions of sugar and milk were used to test the effects of viscosity and pH on the wear rate. The results indicated a significant increase in wear rate in the various solutions, with some correlation between wear rate and increases in viscosity and this was linked to enhance particle entrainment in the more viscous solutions. The generally lower wear rate in tea compared to coffee was associated with a longer ageing period in this solution before uniform wear was observed. Micro-abrasion maps were used to characterize the differences in performance for the material in the environments studied.

  11. Process research into metallic pipe wear of hot chamber die casting machines and methods ofincreasing wear resistance

    NASA Astrophysics Data System (ADS)

    Mukhametzyanova, G. F.; Kolesnikov, MS; Mukhametzyanov, I. R.; Astatshenko, V. I.

    2017-09-01

    The kinetics and reasons for metallic pipe wear of hot chamberzinc alloy die casting machines are established.Increasing metallic pipe wear components wear resistance is being achieved by means of die steelДИ - 22 with electroslag remelting modification and electron-beamremelting modification and after the processes of nitriding and boriding besides.

  12. Degradation of experimental composite materials and in vitro wear simulation

    NASA Astrophysics Data System (ADS)

    Givan, Daniel Allen

    2001-12-01

    The material, mechanical, and clinical aspects of surface degradation of resin composite dental restorative materials by in vitro wear simulation continues to be an area of active research. To investigate wear mechanisms, a series of experimental resin composites with variable and controlled filler particle shape and loading were studied by in vitro wear simulation. The current investigation utilized a simulation that isolated the wear environment, entrapped high and low modulus debris, and evaluated the process including machine and fluid flow dynamics. The degradation was significantly affected by filler particle shape and less by particle loading. The spherical particle composites demonstrated wear loss profiles suggesting an optimized filler loading may exist. This was also demonstrated by the trends in the mechanical properties. Very little difference in magnitude was noted for the wear of irregular particle composites as a function of particulate size; and as a group they were more wear resistant than spherical particle composites. This was the result of different mechanisms of wear that were correlated with the three-dimensional particle shape. The abrasive effects of the aggregate particles and the polymeric stabilization of the irregular shape versus the destabilization and "plucking" of the spherical particles resulted in an unprotected matrix that accounted for significantly greater wear of spherical composite. A model and analysis was developed to explain the events associated with the progressive material wear loss. The initial phase was explained by fatigue-assisted microcracking and loss of material segments in a zone of high stress immediately beneath a point of high stress contact. The early phase was characterized by the development of a small facet primarily by fatigue-assisted microcracking. Although the translation effects were minimal, some three-body and initial two-body wear events were also present. In the late phases, the abrasive effects

  13. Report D : self-consolidating concrete (SCC) for infrastructure elements - creep, shrinkage and abrasion resistance.

    DOT National Transportation Integrated Search

    2012-08-01

    Concrete specimens were fabricated for shrinkage, creep, and abrasion resistance : testing. Variations of self-consolidating concrete (SCC) and conventional concrete were : all tested. The results were compared to previous similar testing programs an...

  14. Brush seal shaft wear resistant coatings

    NASA Astrophysics Data System (ADS)

    Howe, Harold

    1995-03-01

    Brush seals suffer from high wear, which reduces their effectiveness. This work sought to reduce brush seal wear by identifying and testing several industry standard coatings. One of the coatings was developed for this work. It was a co-sprayed PSZ with boron-nitride added for a high temperature dry lubricant. Other coatings tested were a PSZ, chrome carbide and a bare rotor. Testing of these coatings included thermal shocking, tensile testing and wear/coefficient of friction testing. Wear testing consisted of applying a coating to a rotor and then running a sample tuft of SiC ceramic fiber against the coating. Surface speeds at point of contact were slightly over 1000 ft/sec. Rotor wear was noted, as well as coefficient of friction data. Results from the testing indicates that the oxide ceramic coatings cannot withstand the given set of conditions. Carbide coatings will not work because of the need for a metallic binder, which oxidizes in the high heat produced by friction. All work indicated a need for a coating that has a lubricant contained within itself and the coating must be resistant to an oxidizing environment.

  15. IN VITRO WEAR RESISTANCE OF THREE TYPES OF POLYMETHYL METHACRYLATE DENTURE TEETH

    PubMed Central

    Reis, Katia Rodrigues; Bonfante, Gerson; Pegoraro, Luiz Fernando; Conti, Paulo Cesar Rodrigues; de Oliveira, Pedro Cesar Garcia; Kaizer, Osvaldo Bazzan

    2008-01-01

    The wear resistance of denture teeth is important to the longevity of removable prostheses of edentulous patients. The ability of denture teeth to maintain a stable occlusal relationship over time may be influenced by this property. The purpose of this in vitro study was to evaluate the wear resistance of polymethyl methacrylate (PMMA) denture teeth based on their chemical composition when opposed by a ceramic antagonist. The maxillary canines (n=10) of 3 PMMA denture teeth (Trubyte Biotone, cross-linked PMMA; Trilux, highly cross-linked IPN (interpenetrating polymer network)-PMMA; and Vivodent, highly cross-linked PMMA) were secured in an in vitro 2-body wear-testing apparatus that produced sliding contact of the specimens (4.5 cycles/s, sliding distance of 20 mm, under 37°C running water) against glazed or airborne particle abraded ceramic. Wear resistance was measured as height loss (mm) under 300 g (sliding force) after 100,000 cycles, using a digital measuring microscope. Mean values were analyzed by 2-way ANOVA and Tukey's test (α=0.05). The wear of Trubyte Biotone (0.93 ± 0.14 mm) was significantly higher than that of both other types of teeth tested against abraded ceramic (p<0.05). The Vivodent tooth (0.64 ± 0.17 mm) exhibited the best wear resistance among the denture teeth tested against airborne particle abraded ceramic. There were no statistically significant differences (p>0.05) in wear among the 3 denture teeth evaluated against glazed ceramic. Trilux and Vivodent teeth tested against either glazed or airborne particle abraded ceramic did not differ significantly from each other (p<0.05). All teeth showed significantly more wear against airborne particle abraded ceramic than against glazed ceramic (p<0.05). In conclusion, the three types of PMMA denture teeth presented significantly different wear resistance against the abraded ceramic. The high-strength PMMA denture teeth were more wear-resistant than the conventional PMMA denture tooth. PMID

  16. Microhardness and wear resistance of PEO-coated 5754 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Vyaliy, I. E.; Egorkin, V. S.; Sinebryukhov, S. L.; Minaev, A. N.; Gnedenkov, S. V.

    2017-09-01

    We present results of the study aimed at assessing the effect of duty cycle (D) during plasma electrolytic oxidation (PEO) on protective properties of the coatings produced on 5754 aluminum alloy. It is shown that increasing the duty cycle of a microsecond current pulses leads to increased hardness and reduced abrasive wear of the PEO-layers, improving mechanical properties. The obtained data allowed confirming, that increasing the amount of energy consumed for coating growth leads to the formation of thicker PEO-layers with improved tribological properties. The effect of duty cycle during plasma electrolytic oxidation on protective properties of the produced coatings was assessed.

  17. An analysis of the physiologic parameters of intraoral wear: a review

    NASA Astrophysics Data System (ADS)

    Lawson, Nathaniel C.; Janyavula, Sridhar; Cakir, Deniz; Burgess, John O.

    2013-10-01

    This paper reviews the conditions of in vivo mastication and describes a novel method of measuring in vitro wear. Methods: parameters of intraoral wear are reviewed in this analysis, including chewing force, tooth sliding distance, food abrasivity, saliva lubrication, and antagonist properties. Results: clinical measurement of mastication forces indicates a range of normal forces between 20 and 140 N for a single molar. During the sliding phase of mastication, horizontal movement has been measured between 0.9 and 2.86 mm. In vivo wear occurs by three-body abrasion when food particles are interposed between teeth and by two-body abrasion after food clearance. Analysis of food particles used in wear testing reveals that food particles are softer than enamel and large enough to separate enamel and restoration surfaces and act as a solid lubricant. In two-body wear, saliva acts as a boundary lubricant with a viscosity of 3 cP. Enamel is the most relevant antagonist material for wear testing. The shape of a palatal cusp has been estimated as a 0.6 mm diameter ball and the hardest region of a tooth is its enamel surface. pH values and temperatures have been shown to range between 2-7 and 5-55 °C in intraoral fluids, respectively. These intraoral parameters have been used to modify the Alabama wear testing method.

  18. Abrasive Wear of Four Direct Restorative Materials by Standard and Whitening Dentifrices

    DTIC Science & Technology

    2013-06-01

    after an acidic challenge . Enamel loss was significantly greater when erosive and abrasive effects were combined. They concluded that acid-softened...surrounding soft tissues. Another benefit of restoration is the elimination of a challenging area for the patient and hygienist to clean. These areas...abrasion challenge ; the resin cement with the smallest sized filler particles had the smallest weight loss and maintained the smoothest surface of all the

  19. Application of surface analysis to solve problems of wear

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1981-01-01

    Results are presented for the use of surface analytical tools including field ion microscopy, Auger emission spectroscopy analysis (AES), cylindrical mirror Auger analysis and X-ray photoelectron spectroscopy (XPS). Data from the field ion microscope reveal adhesive transfer (wear) at the atomic level with the formation of surface compounds not found in the bulk, and AES reveals that this transfer will occur even in the presence of surface oxides. Both AES and XPS reveal that in abrasive wear with silicon carbide and diamond contacting the transition metals, the surface and the abrasive undergo a chemical or structural change which effects wear. With silicon carbide, silicon volatilizes leaving behind a pseudo-graphitic surface and the surface of diamond is observed to graphitize.

  20. Wear resistance of machine tools' bionic linear rolling guides by laser cladding

    NASA Astrophysics Data System (ADS)

    Wang, Yiqiang; Liu, Botao; Guo, Zhengcai

    2017-06-01

    In order to improve the rolling wear resistance (RWR) of linear rolling guides (LRG) as well as prolong the life of machine tools, various shape samples with different units spaces ranged from 1 to 5 mm are designed through the observation of animals in the desert and manufactured by laser cladding. Wear resistance tests reproducing closely the real operational condition are conducted by using a homemade linear reciprocating wear test machine, and wear resistance is evaluated by means of weight loss measurement. Results indicate that the samples with bionic units have better RWR than the untreated one, of which the reticulate treated sample with unit space 3 mm present the best RWR. More specifically, among the punctuate treated samples, the mass loss increases with the increase of unit space; among the striate treated samples, the mass loss changes slightly with the increase of unit space, attaining a minimum at the unit space of 4 mm; among the reticulate treated samples, with the increase of unit space, the mass loss initially decreases, but turns to increase after reaching a minimum at the unit space of 3 mm. Additionally, the samples with striate shape perform better wear resistance than the other shape groups on the whole. From the ratio value of laser treated area to contacted area perspective, that the samples with ratio value between 0.15 and 0.3 possess better wear resistance is concluded.

  1. The in vivo wear resistance of 12 composite resins.

    PubMed

    Lang, B R; Bloem, T J; Powers, J M; Wang, R F

    1992-09-01

    The in vivo wear resistance of 12 composite resins were compared with an amalgam control using the Latin Square experimental design. Sixteen edentulous patients wearing specially designed complete dentures formed the experimental population. The Michigan Computer Graphics Measurement System was used to digitize the surface of the control and composite resin samples before and after 3-month test periods to obtain wear data. The 12 composite resins selected for this investigation based on their published composite classification types were seven fine particle composites, three blends, and two microfilled composite resins. The Latin Square experimental design was found to be valid with the factor of material being statistically different at the 5% level of significance. Wear was computed as volume loss (mm3/mm2), and all of the composites studied had more wear than the amalgam control (P = .001). After 3 months, the mean (error) of wear of the amalgam was 0.028 (0.006). Means (error) of wear for the 12 composites were ranked from most to least wear by mean wear volume loss. The absence of any relationship between mean wear volume loss and the volume percentage filler was confirmed by the correlation coefficient r = -0.158.

  2. Design and evaluation of high-volume fly ash (HVFA) concrete mixes, report D : creep, shrinkage, and abrasion resistance of HVFA concrete.

    DOT National Transportation Integrated Search

    2012-10-01

    The main objective of this study was to determine the effect on shrinkage, creep, : and abrasion resistance of high-volume fly ash (HVFA) concrete. The HVFA concrete : test program consisted of comparing the shrinkage, creep, and abrasion performance...

  3. The efficacy of a highly concentrated fluoride dentifrice on bovine enamel subjected to erosion and abrasion.

    PubMed

    Rios, Daniela; Magalhães, Ana Carolina; Polo, Renata Ocon Braga; Wiegand, Annette; Attin, Thomas; Buzalaf, Marilia Afonso Rabelo

    2008-12-01

    Researchers have proposed the use of fluoride for the prevention of enamel wear; however, only limited information is available about the impact of fluoridated dentifrices. Because tooth wear is a well-recognized dental problem, the authors conducted an in situ, ex vivo study to assess the efficacy of a highly concentrated fluoride dentifrice on bovine enamel subjected to erosion and abrasion. The authors conducted a double-blind, crossover in situ study consisting of three phases (seven days each). In each phase, the authors tested one of the dentifrices (5,000 parts per million fluoride [F]; 1,100 ppm F; no F). They performed erosive challenges with the use of cola drink (60 seconds, four times per day) and abrasive challenges via toothbrushing (30 seconds, four times per day). The authors determined the enamel loss via profilometry. The authors tested the data by using two-way analysis of variance (P < .05). For the erosion-plus-abrasion condition, the study results showed that enamel wear was significantly higher than that with erosion alone. The findings showed no significant differences between the dentifrices regarding enamel wear. Within the in situ, ex vivo conditions of this study, the authors concluded that the highly concentrated fluoride dentifrice did not have a protective effect on enamel against erosion and erosion plus toothbrushing abrasion. Patients at risk of developing enamel erosion should benefit from preventive measures other than fluoride dentifrice, because even a highly concentrated fluoride dentifrice does not appear to prevent enamel erosion.

  4. Influence of different toothpaste abrasives on the bristle end-rounding quality of toothbrushes.

    PubMed

    de Oliveira, G J P L; de Aveiro, J M; Pavone, C; Marcantonio, R A C

    2015-02-01

    To evaluate the influence of different toothpaste abrasives on the bristle wear and bristle tip morphology of toothbrushes with different degrees of hardness. Ninety samples of bovine incisor teeth were used in this study. The samples were randomly divided into three groups according to the bristle hardness of the toothbrush used: soft bristles (S); extra-soft bristles (ES); hard bristles (H). The toothbrushes of each group were randomly divided into six subgroups with five toothbrushes each, according to the abrasive of the toothpaste used in the simulation: Negative control (distilled water); toothpaste 1 (silica); toothpaste 2 (hydrated silica); toothpaste 3 (calcium carbonate, calcium bicarbonate and silica); toothpaste 4 (tetrapotassium pyrophosphate, silica and titanium dioxide); toothpaste 5 (calcium carbonate). The samples were placed in a toothbrushing simulating machine that simulating three months of brushing. The toothbrush bristles were evaluated by the bristle wear index, and the bristle tips morphology was evaluated by the bristle tip morphology index. The ES brush presented the highest bristle wear among the toothbrushes. Additionally, the S brushes showed better morphology of the bristles followed by ES and H brushes. The type of abrasive only influenced the bristle tip morphology of the ES brushes. The toothpaste 3 induced the worse bristle tip morphology than all the other toothpastes. Different abrasives have influence only on the bristle tip morphology of the ES brushes. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Comparison of Wear Resistance of Hawley and Vacuum Formed Retainers: An in-vitro Study.

    PubMed

    V, Moshkelgosha; M, Shomali; M, Momeni

    2016-06-01

    As a physical property, wear resistance of the materials used in the fabrication of orthodontic retainers play a significant role in the stability and long term use of the appliances. To evaluate the wear resistance of two commonly used materials for orthodontic retainers: Acropars OP, i.e. a polymethyl methacrylate based material, and 3A-GS060, i.e. a polyethylene based material. For each material, 30 orthodontic retainers were made according to the manufacturers' instructions and a 30×30×2 mm block was cut out from the mid- palatal area of each retainer. Each specimen underwent 1000 cycles of wear stimulation in a pin on disc machine. The depth of wear of each specimen was measured using a Nano Wizard II atomic force microscope in 3 random points of each specimen's wear trough. The average of these three measurements was calculated and considered as mean value wear depth of each specimen (µm). The mean wear depth was 6.10µm and 2.15µm for 3A-GS060 and Acropars OP groups respectively. Independent t-test showed a significant difference between the two groups ( p < 0.001). The results show Polymethyl methacrylate base (Acropars) is more wear resistance than the polyethylene based material (3A-GS060). As the higher wear resistance of the fabrication material can improve the retainers' survival time and its cost-effectiveness, VFRs should be avoided in situations that the appliance needs high wear resistance such as bite blocks opposing occlusal forces.

  6. Comparison of Wear Resistance of Hawley and Vacuum Formed Retainers: An in-vitro Study

    PubMed Central

    V, Moshkelgosha; M, Shomali; M, Momeni

    2016-01-01

    Statement of Problem: As a physical property, wear resistance of the materials used in the fabrication of orthodontic retainers play a significant role in the stability and long term use of the appliances. Objectives: To evaluate the wear resistance of two commonly used materials for orthodontic retainers: Acropars OP, i.e. a polymethyl methacrylate based material, and 3A-GS060, i.e. a polyethylene based material. Materials and Methods: For each material, 30 orthodontic retainers were made according to the manufacturers’ instructions and a 30×30×2 mm block was cut out from the mid- palatal area of each retainer. Each specimen underwent 1000 cycles of wear stimulation in a pin on disc machine. The depth of wear of each specimen was measured using a Nano Wizard II atomic force microscope in 3 random points of each specimen’s wear trough. The average of these three measurements was calculated and considered as mean value wear depth of each specimen (µm). Results: The mean wear depth was 6.10µm and 2.15µm for 3A-GS060 and Acropars OP groups respectively. Independent t-test showed a significant difference between the two groups (p < 0.001). The results show Polymethyl methacrylate base (Acropars) is more wear resistance than the polyethylene based material (3A-GS060). Conclusions: As the higher wear resistance of the fabrication material can improve the retainers’ survival time and its cost-effectiveness, VFRs should be avoided in situations that the appliance needs high wear resistance such as bite blocks opposing occlusal forces. PMID:28959750

  7. Tooth wear in captive giraffes (Giraffa camelopardalis): mesowear analysis classifies free-ranging specimens as browsers but captive ones as grazers.

    PubMed

    Clauss, Marcus; Franz-Odendaal, Tamara A; Brasch, Juliane; Castell, Johanna C; Kaiser, Thomas

    2007-09-01

    Captive giraffe (Giraffa camelopardalis) mostly do not attain the longevity possible for this species and frequently have problems associated with low energy intake and fat storage mobilization. Abnormal tooth wear has been among the causes suggested as an underlying problem. This study utilizes a tooth wear scoring method ("mesowear") primarily used in paleobiology. This scoring method was applied to museum specimens of free-ranging (n=20) and captive (n=41) giraffes. The scoring system allows for the differentiation between attrition--(typical for browsers, as browse contains little abrasive silica) and abrasion--(typical for grazers, as grass contains abrasive silica) dominated tooth wear. The dental wear pattern of the free-ranging population is dominated by attrition, resembles that previously published for free-ranging giraffe, and clusters within browsing herbivores in comparative analysis. In contrast, the wear pattern of the captive population is dominated by abrasion and clusters among grazing herbivores in comparative analyses. A potential explanation for this difference in tooth wear is likely related to the content of abrasive elements in zoo diets. Silica content (measured as acid insoluble ash) is low in browse and alfalfa. However, grass hay and the majority of pelleted compound feeds contain higher amounts of silica. It can be speculated that the abnormal wear pattern in captivity compromises tooth function in captive giraffe, with deleterious long-term consequences.

  8. Friction and wear with a single-crystal abrasive grit of silicon carbide in contact with iron base binary alloys in oil: Effects of alloying element and its content

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1979-01-01

    Sliding friction experiments were conducted with various iron-base binary alloys (alloying elements were Ti, Cr, Mn, Ni, Rh, and W) in contact with a rider of 0.025-millimeter-radius, single-crystal silicon carbide in mineral oil. Results indicate that atomic size and content of alloying element play a dominant role in controlling the abrasive-wear and -friction properties of iron-base binary alloys. The coefficient of friction and groove height (wear volume) general alloy decrease, and the contact pressure increases in solute content. There appears to be very good correlation of the solute to iron atomic radius ratio with the decreasing rate of coefficient of friction, the decreasing rate of groove height (wear volume), and the increasing rate of contact pressure with increasing solute content C. Those rates increase as the solute to iron atomic radius ratio increases from unity.

  9. [Polyethylene abrasion: cause or consequence of an endoprosthesis loosening? Investigations of firm and loosened hip implants].

    PubMed

    Busse, B; Niecke, M; Püschel, K; Delling, G; Katzer, A; Hahn, M

    2007-01-01

    Periprosthetic tissue was analysed by the combination of different investigation techniques without destruction. The localisation and geometry of polyethylene abrasion particles were determined quantitatively to differentiate between abrasion due to function and abrasion due to implant loosening. Non-polyethylene particles from implant components which contaminate the tissue were micro-analytically measured. The results will help us to understand loosening mechanisms and thus lead to implant optimisations. A non-destructive particle analysis using highly sensitive proton-induced X-ray emission (PIXE) was developed to achieve a better histological allocation. Five autopsy cases with firmly fitting hip endoprosthesis (2 x Endo-Modell Mark III, 1 x St. Georg Mark II, LINK, Germany; 2 x Spongiosa Metal II, ESKA, Germany) were prepared as ground tissue specimens. Wear investigations were accomplished with a combined application of different microscopic techniques and microanalysis. The abrasion due to implant loosening was histologically evaluated on 293 loosened cup implants (St. Georg Mark II, LINK, Germany). Wear particles are heterogeneously distributed in the soft tissue. In cases of cemented prostheses, cement particles are dominating whereas metal particles could rarely be detected. The concentration of the alloy constituent cobalt (Co) is increased in the mineralised bone tissue. The measured co-depositions depend on the localisation and/or lifetime of an implant. Functional polyethylene (PE) abrasion needs to be differentiated from PE abrasion of another genesis (loosening, impingement) morphologically and by different tissue reactions. In the past a reduction of abrasion was targeted primarily by the optimisation of the bearing surfaces and tribology. The interpretation of our findings indicates that different mechanisms of origin in terms of tissue contamination with wear debris and the alloy should be included in the improvement of implants or implantation

  10. Brushing force of manual and sonic toothbrushes affects dental hard tissue abrasion.

    PubMed

    Wiegand, Annette; Burkhard, John Patrik Matthias; Eggmann, Florin; Attin, Thomas

    2013-04-01

    This study aimed to determine the brushing forces applied during in vivo toothbrushing with manual and sonic toothbrushes and to analyse the effect of these brushing forces on abrasion of sound and eroded enamel and dentin in vitro. Brushing forces of a manual and two sonic toothbrushes (low and high frequency mode) were measured in 27 adults before and after instruction of the respective brushing technique and statistically analysed by repeated measures analysis of variance (ANOVA). In the in vitro experiment, sound and eroded enamel and dentin specimens (each subgroup n = 12) were brushed in an automatic brushing machine with the respective brushing forces using a fluoridated toothpaste slurry. Abrasion was determined by profilometry and statistically analysed by one-way ANOVA. Average brushing force of the manual toothbrush (1.6 ± 0.3 N) was significantly higher than for the sonic toothbrushes (0.9 ± 0.2 N), which were not significantly different from each other. Brushing force prior and after instruction of the brushing technique was not significantly different. The manual toothbrush caused highest abrasion of sound and eroded dentin, but lowest on sound enamel. No significant differences were detected on eroded enamel. Brushing forces of manual and sonic toothbrushes are different and affect their abrasive capacity. Patients with severe tooth wear and exposed and/or eroded dentin surfaces should use sonic toothbrushes to reduce abrasion, while patients without tooth wear or with erosive lesions confining only to enamel do not benefit from sonic toothbrushes with regard to abrasion.

  11. Process Monitoring Evaluation and Implementation for the Wood Abrasive Machining Process

    PubMed Central

    Saloni, Daniel E.; Lemaster, Richard L.; Jackson, Steven D.

    2010-01-01

    Wood processing industries have continuously developed and improved technologies and processes to transform wood to obtain better final product quality and thus increase profits. Abrasive machining is one of the most important of these processes and therefore merits special attention and study. The objective of this work was to evaluate and demonstrate a process monitoring system for use in the abrasive machining of wood and wood based products. The system developed increases the life of the belt by detecting (using process monitoring sensors) and removing (by cleaning) the abrasive loading during the machining process. This study focused on abrasive belt machining processes and included substantial background work, which provided a solid base for understanding the behavior of the abrasive, and the different ways that the abrasive machining process can be monitored. In addition, the background research showed that abrasive belts can effectively be cleaned by the appropriate cleaning technique. The process monitoring system developed included acoustic emission sensors which tended to be sensitive to belt wear, as well as platen vibration, but not loading, and optical sensors which were sensitive to abrasive loading. PMID:22163477

  12. Formation of nano-laminated structures in a dry sliding wear-induced layer under different wear mechanisms of 20CrNi2Mo steel

    NASA Astrophysics Data System (ADS)

    Yin, Cun-hong; Liang, Yi-long; Jiang, Yun; Yang, Ming; Long, Shao-lei

    2017-11-01

    The microstructures of 20CrNi2Mo steel underneath the contact surface were examined after dry sliding. Scanning Electronic Microscopy (SEM), Transmission Electron Microscopy (TEM), Electron Backscattered Diffraction (EBSD) and an ultra-micro-hardness tester were used to characterize the worn surface and dry sliding wear-induced layer. Martensite laths were ultra-refined due to cumulative strains and a large strain gradient that occurred during cyclic loading in wear near the surface. The microstructure evolution in dominant abrasive wear differs from that in adhesive wear. In dominant abrasive wear, only bent martensite laths with high-density deformation dislocations were observed. In contrast, in dominant adhesive wear, gradient structures were formed along the depth from the wear surface. Cross-sectional TEM foils were prepared in a focused ion beam (FIB) to observe the gradient structures in a dry sliding wear-induced layer at depths of approximately 1-5 μm and 5-20 μm. The gradient structures contained nano-laminated structures with an average thickness of 30-50 nm and bent martensite laths. We found that the original martensite laths coordinated with the strain energy and provided origin boundaries for the formation of gradient structures. Geometrically necessary boundaries (GNBs) and isolated dislocation boundaries (IDBs) play important roles in forming the nano-laminated structures.

  13. Research into properties of wear resistant ceramic metal plasma coatings

    NASA Astrophysics Data System (ADS)

    Ivancivsky, V. V.; Skeeba, V. Yu; Zverev, E. A.; Vakhrushev, N. V.; Parts, K. A.

    2018-03-01

    The study considers one of the promising ways to improve the quality of wear resistant plasma ceramic coatings by implementing various powder mixtures. The authors present the study results of the nickel-ceramic and cobalt-ceramic coating properties and describe the specific character of the investigated coatings composition. The paper presents the results of the coating microhardness, chemical and adhesive strength studies. The authors conducted wear resistance tests of composite coatings in comparison with the plasma coatings of initial powder components.

  14. Anti-wear Mechanism Analysis of Nano-CaCO3 Additives

    NASA Astrophysics Data System (ADS)

    Xu, Zhen; Sun, Junfeng

    2018-06-01

    In this paper, the wear test was carried on with cylinder piston by the wear test device, receiving the results of the piston ring wear and abrasive characteristics by monitoring the wear process, the thesis analysis and put forward the nano-CaCO3 lubricating oil additive anti wear mechanism by the ferrography analysis technology, and provide the technical reference for the relevant measures to reduce wear and the friction, and provide reference value for further study on the related theories of reducing wear and reducing friction.

  15. Wear and corrosion resistance of electroforming layer after WEDM for 7075 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Xu, Jinkai; Qiu, Rongxian; Lian, Zhongxu; Yu, Zhanjiang; Yu, Peng; Ren, Wanfei; Yu, Huadong

    2018-06-01

    In order to investigate the influence of the recast layer obtained by wire electrical discharge machining (WEDM) for 7075 aluminum alloy on the mechanical physical properties of the workpiece, we carried out research on the geometry parameters, microstructure, adhesion, wear resistance and corrosion resistance of the recast layer. The results show that the unit thermal power density decreases, the surface roughness Ra value increases, and the amount of the electric erosion craters and the micro/nano pits decrease with the increase of current and voltage. In the meantime, the thickness and hardness of the recast layer are increased, so the wear resistance and corrosion resistance are significantly improved. In addition, the surface hardness plays a major role in increasing wear resistance.

  16. A new methodology for hydro-abrasive erosion tests simulating penstock erosive flow

    NASA Astrophysics Data System (ADS)

    Aumelas, V.; Maj, G.; Le Calvé, P.; Smith, M.; Gambiez, B.; Mourrat, X.

    2016-11-01

    Hydro-abrasive resistance is an important property requirement for hydroelectric power plant penstock coating systems used by EDF. The selection of durable coating systems requires an experimental characterization of coating performance. This can be achieved by performing accelerated and representative laboratory tests. In case of severe erosion induced by a penstock flow, there is no suitable method or standard representative of real erosive flow conditions. The presented study aims at developing a new methodology and an associated laboratory experimental device. The objective of the laboratory apparatus is to subject coated test specimens to wear conditions similar to the ones generated at the penstock lower generatrix in actual flow conditions. Thirteen preselected coating solutions were first been tested during a 45 hours erosion test. A ranking of the thirteen coating solutions was then determined after characterisation. To complete this first evaluation and to determine the wear kinetic of the four best coating solutions, additional erosion tests were conducted with a longer duration of 216 hours. A comparison of this new method with standardized tests and with real service operating flow conditions is also discussed. To complete the final ranking based on hydro-abrasive erosion tests, some trial tests were carried out on penstock samples to check the application method of selected coating systems. The paper gives some perspectives related to erosion test methodologies for materials and coating solutions for hydraulic applications. The developed test method can also be applied in other fields.

  17. [Clinical study on the distribution of tooth wear of the adult population].

    PubMed

    Curcă, Magdalena; Dănilă, I

    2010-01-01

    Tooth wear is becoming increasingly significant in the developed societies, because the etiological factors are frequently present in the daily life. The aim of this study was to assess the distribution of the tooth wear of the adult population in a private practice of dentistry. The group of study had 614 patients, structured on the following subgroups of age: 18- 30 years, 31-40, 41-50, 51-65 and more than 65 years old. Each patient had a clinical exam and a questionnaire for the diet and the lifestyle, spotlighting the etiology of tooth wear. attrition was the most frequent (55.7%), followed by abrasion (32.7%), erosion affected 7.5% of the patients and abfractions are the least frequent (4.1%). Erosions (9.7%) and attritions (59.9%) are more frequent at the feminine gender, and abrasions (40.4%) at the masculine gender. More than half of the abfractions (56%) were found at the youth patients (18-30 years old). Erosions were found in the 31-40 years subgroup at almost 40% of the patients; in the 41-50 years subgroup, abrasion and erosion were found in equal proportions. Abrasion prevails at the 51-65 years subgroup (30.8%). 72% of the consumers of acidic fruits had dental erosions. Tooth wear is under the influence of the diet and the age factor.

  18. The production and tribology of hard facing coatings for agricultural applications

    NASA Astrophysics Data System (ADS)

    Roffey, Paul

    Abrasive wear is a significant issue in many industries but is of particular significance in agriculture. This research is being carried out due to the demand for a hard wearing, economical coating for use in the agricultural industry.A primary objective has been to review and develop an in depth understanding of the type of wear suffered by metal shares in agricultural soils. The affect of soil properties and abrasive wear environments on the amount of wear that occurs, and the way in which material properties can be used to reduce or prevent this has also been investigated. A review of the diverse range of soil properties, such as the mineral content, moisture content, soils strengths has been carried out in order to create an appropriate wear test procedure.The coatings developed for testing were modifications to an existing powder metallurgy coating. The modifications were made by the addition of selected hard phases to the powder prior to sintering. The resulting materials were characterised in terms of sinterability, hardness and abrasive wear resistance. Prior to commencing this work little or no data existed on the wear performance of the pre-existing coating. Wear resistance has been measured using a fixed ball micro-scale abrasive wear test (also known as the ball-cratering wear test) with SiC and SiO2 abrasives and also using a modified version of the ASTM G65 abrasive wear test which allowed testing in dry and wet modes. Limited field trials were performed to determine the abrasive wear resistance in real soil. Results from wear testing have determined that the optimum modification to the coating can improve performance compared to the unmodified coating.Detailed scanning electron microscopy (SEM) has been performed on the wear scars and has revealed the resultant wear mechanisms and role that the hard phase additions play in improving the wear resistance. The influence of the hard phase addition on the microstructure has also been studied.The wear

  19. 3D FEM Simulation of Flank Wear in Turning

    NASA Astrophysics Data System (ADS)

    Attanasio, Aldo; Ceretti, Elisabetta; Giardini, Claudio

    2011-05-01

    This work deals with tool wear simulation. Studying the influence of tool wear on tool life, tool substitution policy and influence on final part quality, surface integrity, cutting forces and power consumption it is important to reduce the global process costs. Adhesion, abrasion, erosion, diffusion, corrosion and fracture are some of the phenomena responsible of the tool wear depending on the selected cutting parameters: cutting velocity, feed rate, depth of cut, …. In some cases these wear mechanisms are described by analytical models as a function of process variables (temperature, pressure and sliding velocity along the cutting surface). These analytical models are suitable to be implemented in FEM codes and they can be utilized to simulate the tool wear. In the present paper a commercial 3D FEM software has been customized to simulate the tool wear during turning operations when cutting AISI 1045 carbon steel with uncoated tungsten carbide tip. The FEM software was improved by means of a suitable subroutine able to modify the tool geometry on the basis of the estimated tool wear as the simulation goes on. Since for the considered couple of tool-workpiece material the main phenomena generating wear are the abrasive and the diffusive ones, the tool wear model implemented into the subroutine was obtained as combination between the Usui's and the Takeyama and Murata's models. A comparison between experimental and simulated flank tool wear curves is reported demonstrating that it is possible to simulate the tool wear development.

  20. Wear Mechanism of Chemical Vapor Deposition (CVD) Carbide Insert in Orthogonal Cutting Ti-6Al-4V ELI at High Cutting Speed

    NASA Astrophysics Data System (ADS)

    Gusri, A. I.; Che Hassan, C. H.; Jaharah, A. G.

    2011-01-01

    The performance of Chemical Vapor Deposition (CVD) carbide insert with ISO designation of CCMT 12 04 04 LF, when turning titanium alloys was investigated. There were four layers of coating materials for this insert i.e.TiN-Al2O3-TiCN-TiN. The insert performance was evaluated based on the insert's edge resistant towards the machining parameters used at high cutting speed range of machining Ti-6Al-4V ELI. Detailed study on the wear mechanism at the cutting edge of CVD carbide tools was carried out at cutting speed of 55-95 m/min, feed rate of 0.15-0.35 mm/rev and depth of cut of 0.10-0.20 mm. Wear mechanisms such as abrasive and adhesive were observed on the flank face. Crater wear due to diffusion was also observed on the rake race. The abrasive wear occurred more at nose radius and the fracture on tool were found at the feed rate of 0.35 mm/rev and the depth of cut of 0.20 mm. The adhesion wear takes place after the removal of the coating or coating delaminating. Therefore, adhesion or welding of titanium alloy onto the flank and rake faces demonstrates a strong bond at the workpiece-tool interface.

  1. Mechanism-Based FE Simulation of Tool Wear in Diamond Drilling of SiCp/Al Composites.

    PubMed

    Xiang, Junfeng; Pang, Siqin; Xie, Lijing; Gao, Feinong; Hu, Xin; Yi, Jie; Hu, Fang

    2018-02-07

    The aim of this work is to analyze the micro mechanisms underlying the wear of macroscale tools during diamond machining of SiC p /Al6063 composites and to develop the mechanism-based diamond wear model in relation to the dominant wear behaviors. During drilling, high volume fraction SiC p /Al6063 composites containing Cu, the dominant wear mechanisms of diamond tool involve thermodynamically activated physicochemical wear due to diamond-graphite transformation catalyzed by Cu in air atmosphere and mechanically driven abrasive wear due to high-frequency scrape of hard SiC reinforcement on tool surface. An analytical diamond wear model, coupling Usui abrasive wear model and Arrhenius extended graphitization wear model was proposed and implemented through a user-defined subroutine for tool wear estimates. Tool wear estimate in diamond drilling of SiC p /Al6063 composites was achieved by incorporating the combined abrasive-chemical tool wear subroutine into the coupled thermomechanical FE model of 3D drilling. The developed drilling FE model for reproducing diamond tool wear was validated for feasibility and reliability by comparing numerically simulated tool wear morphology and experimentally observed results after drilling a hole using brazed polycrystalline diamond (PCD) and chemical vapor deposition (CVD) diamond coated tools. A fairly good agreement of experimental and simulated results in cutting forces, chip and tool wear morphologies demonstrates that the developed 3D drilling FE model, combined with a subroutine for diamond tool wear estimate can provide a more accurate analysis not only in cutting forces and chip shape but also in tool wear behavior during drilling SiC p /Al6063 composites. Once validated and calibrated, the developed diamond tool wear model in conjunction with other machining FE models can be easily extended to the investigation of tool wear evolution with various diamond tool geometries and other machining processes in cutting different

  2. Mechanism-Based FE Simulation of Tool Wear in Diamond Drilling of SiCp/Al Composites

    PubMed Central

    Xiang, Junfeng; Pang, Siqin; Xie, Lijing; Gao, Feinong; Hu, Xin; Yi, Jie; Hu, Fang

    2018-01-01

    The aim of this work is to analyze the micro mechanisms underlying the wear of macroscale tools during diamond machining of SiCp/Al6063 composites and to develop the mechanism-based diamond wear model in relation to the dominant wear behaviors. During drilling, high volume fraction SiCp/Al6063 composites containing Cu, the dominant wear mechanisms of diamond tool involve thermodynamically activated physicochemical wear due to diamond-graphite transformation catalyzed by Cu in air atmosphere and mechanically driven abrasive wear due to high-frequency scrape of hard SiC reinforcement on tool surface. An analytical diamond wear model, coupling Usui abrasive wear model and Arrhenius extended graphitization wear model was proposed and implemented through a user-defined subroutine for tool wear estimates. Tool wear estimate in diamond drilling of SiCp/Al6063 composites was achieved by incorporating the combined abrasive-chemical tool wear subroutine into the coupled thermomechanical FE model of 3D drilling. The developed drilling FE model for reproducing diamond tool wear was validated for feasibility and reliability by comparing numerically simulated tool wear morphology and experimentally observed results after drilling a hole using brazed polycrystalline diamond (PCD) and chemical vapor deposition (CVD) diamond coated tools. A fairly good agreement of experimental and simulated results in cutting forces, chip and tool wear morphologies demonstrates that the developed 3D drilling FE model, combined with a subroutine for diamond tool wear estimate can provide a more accurate analysis not only in cutting forces and chip shape but also in tool wear behavior during drilling SiCp/Al6063 composites. Once validated and calibrated, the developed diamond tool wear model in conjunction with other machining FE models can be easily extended to the investigation of tool wear evolution with various diamond tool geometries and other machining processes in cutting different workpiece

  3. Effect of bionic coupling units' forms on wear resistance of gray cast iron under dry linear reciprocating sliding condition

    NASA Astrophysics Data System (ADS)

    Pang, Zuobo; Zhou, Hong; Xie, Guofeng; Cong, Dalong; Meng, Chao; Ren, Luquan

    2015-07-01

    In order to get close to the wear form of guide rails, the homemade linear reciprocating wear testing machine was used for the wear test. In order to improve the wear-resistance of gray cast iron guide rail, bionic coupling units of different forms were manufactured by a laser. Wear behavior of gray-cast-iron with bionic-coupling units has been studied under dry sliding condition at room temperature using the wear testing machine. The wear resistance was evaluated by means of weight loss measurement and wear morphology. The results indicated that bionic coupling unit could improve the wear resistance of gray cast iron. The wear resistance of gray cast iron with reticulation bionic coupling unit is the best. When the load and speed changed, reticulation bionic coupling unit still has excellent performance in improving the wear resistance of gray cast iron.

  4. Microstructure and dry-sliding wear properties of DC plasma nitrided 17-4 PH stainless steel

    NASA Astrophysics Data System (ADS)

    Li, Gui-jiang; Wang, Jun; Li, Cong; Peng, Qian; Gao, Jian; Shen, Bao-luo

    2008-05-01

    An attempt that the precipitation hardening steel 17-4PH was conducted by DC plasma nitriding (DCPN) is made to develop a kind of candidate material for nuclear reactor. Nitriding process performed at temperature ⩽ 400 °C takes effect on creation of the layers composed of S-phase (expanded austenite) and αN‧ (expanded martensite). Up to the temperature of 420 °C, the S-phase peaks disappear due to the transformation occurrence (S-phase → αN‧ + CrN). For the samples nitrided at temperature ⩾ 450 °C, no evidence of αN‧ is found owing to a precipitation (αN‧ → α +CrN) taking place. For the 480 °C/4 h treated sample, it is the surface microhardness that plays the lead role in the wear rate reduction but the surface roughness; while for the 400 °C/4 h treated sample, it is both of the surface roughness and the S-phase formation. Dry sliding wear of the untreated 17-4PH is mainly characterized by strong adhesion, abrasion and oxidation mechanism. Samples nitrided at 400 °C which is dominated by slight abrasion and plastic deformation exhibit the best dry sliding wear resistance compared to the samples nitrided at other temperatures.

  5. Effects of toothbrush hardness on in vitro wear and roughness of composite resins.

    PubMed

    Kyoizumi, Hideaki; Yamada, Junji; Suzuki, Toshimitsu; Kanehira, Masafumi; Finger, Werner J; Sasaki, Keiichi

    2013-11-01

    To investigate and compare the effects of toothbrushes with different hardness on abrasion and surface roughness of composite resins. Toothbrushes (DENT. EX Slimhead II 33, Lion Dental Products Co. Ltd., Tokyo, Japan) marked as soft, medium and hard, were used to brush 10 beam-shaped specimens of each of three composites resins (Venus [VEN], Venus Diamond [VED] and Venus Pearl [VEP]; HeraeusKulzer) with standardized calcium carbonate slurry in a multistation testing machine (2N load, 60 Hz). After each of five cycles with 10k brushing strokes the wear depth and surface roughness of the specimens were determined. After completion of 50k strokes representative samples were inspected by SEM. Data were treated with ANOVA and regression analyses (p < 0.05). Abrasion of the composite resins increased linearly with increasing number of brushing cycles (r² > 0.9). Highest wear was recorded for VEN, lowest for VED. Hard brushes produced significantly higher wear on VEN and VEP, whereas no difference in wear by toothbrush type was detected for VED. Significantly highest surface roughness was found on VED specimens (Ra > 1.5 µm), the lowest one on VEN (Ra < 0.3 µm). VEN specimens showed increased numbers of pinhole defects when brushed with hard toothbrushes, surfaces of VEP were uniformly abraded without level differences between the prepolymerized fillers and the glass filler-loaded matrix, VED showed large glass fillers protruding over the main filler-loaded matrix portion under each condition. Abrasion and surface roughness of composite resins produced by toothbrushing with dentifrice depend mainly on the type of restorative resin. Hardness grades of toothbrushes have minor effects only on abrasion and surface roughness of composite resins. No relationship was found between abrasion and surface roughness. The grade of the toothbrush used has minor effect on wear, texture and roughness of the composite resin.

  6. Tribological evaluation of high-speed steels with a regulated carbide phase

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Richter, Janusz

    2003-06-15

    Wear resistance of a commercial steel and titanium-niobium high-speed steels with a regulated carbide phase was evaluated by employing a micro-scale abrasive wear test with alumina particles. The worn volumes and corresponding wear coefficients were the lowest for the new non-ledeburitic grades containing titanium, then the two niobium grades, the conventional (both wrought and by powder metallurgy) steels exhibited the worse wear resistance. Fractography SEM observations together with energy-dispersive X-ray (EDX) chemical analysis revealed the decisive role of the steels' MC particles in the wear process. These carbides influenced the abrasion by stoppage of the wear scars and/or changing theirmore » trajectories. Directional and nondirectional abrasion modes in the steels tested using alumina and carborundum abrasives were found and are discussed.« less

  7. Tribological Properties of CrAlN and TiN Coatings Tested in Nano- and Micro-scale Laboratory Wear Tests

    NASA Astrophysics Data System (ADS)

    Hong, Ling; Bian, Guangdong; Hu, Shugen; Wang, Linlin; Dacosta, Herbert

    2015-07-01

    We investigated the tribological properties of CrAlN and TiN coatings produced by electron beam plasma-assisted physical vapor deposition by nano- and micro-scale wear tests. For comparison, we also conducted nano-indentation, nano-scanning wear tests, and pin-on-disk tribotests on uncoated M2 steel. The results indicate that, after nano-scale sliding tests against diamond indenter and pin-on-disk tests against ceramic alumina counterface pins, the CrAlN coating presents superior abrasive wear resistance compared to the TiN-coated and uncoated M2 steel samples. Against aluminum counterface, aluminum is more prone to attach on the CrAlN coating surface compared to TiN coating, but no apparent adhesive wear was observed, which has occurred on the TiN coating.

  8. Enhancement of wear and corrosion resistance of low modulus β-type Zr-20Nb-xTi (x=0, 3) dental alloys through thermal oxidation treatment.

    PubMed

    Zhang, Jianfeng; Gan, Xiaxia; Tang, Hongqun; Zhan, Yongzhong

    2017-07-01

    In order to obtain material with low elastic modulus, good abrasion resistance and high corrosion stability as screw for dental implant, the biomedical Zr-20Nb and Zr-20Nb-3Ti alloy with low elastic modulus were thermal oxidized respectively at 700°C for 1h and 600°C for 1.25h to obtain the compact oxidized layer to improve its wear resistance and corrosion resistance. The results show that smooth compact oxidized layer (composed of monoclinic ZrO 2 , tetragonal ZrO 2 and 6ZrO 2 -Nb 2 O 5 ) with 22.6μm-43.5μm thickness and 1252-1306HV hardness can be in-situ formed on the surface of the Zr-20Nb-xTi (x=0, 3). The adhesion of oxidized layers to the substrates is determined to be 58.35-66.25N. The oxidized Zr-20Nb-xTi alloys reveal great improvement of the pitting corrosion resistance in comparison with the un-oxidized alloys. In addition, the oxidized Zr-20Nb-3Ti exhibits sharply reduction of the corrosion rates and the oxidized Zr-20Nb shows higher corrosion rates than un-oxidized alloys, which is relevant with the content of the t-ZrO 2 . Wear test in artificial saliva demonstrates that the wear losses of the oxidized Zr-20Nb-xTi (x=0, 3) are superior to pure Ti. All of the un-oxidized Zr-20Nb-xTi (x=0, 3) alloys suffer from serious adhesive wear due to its high plasticity. Because of the protection from compact oxide layer with high adhesion and high hardness, the coefficients of friction and wear losses of the oxidized Zr-20Nb-xTi (x=0, 3) alloys decrease 50% and 95%, respectively. The defects on the oxidized Zr-20Nb have a negative effect on the friction and wear properties. In addition, after the thermal oxidation, compression test show that elastic modulus and strength of Zr-20Nb-xTi (x=0, 3) increase slightly with plastic deformation after 40% of transformation. Furthermore, stripping of the oxidized layer from the alloy matrix did not occur during the whole experiments. As the surface oxidized Zr-20Nb-3Ti alloy has a combination of excellent performance

  9. Applicability of Macroscopic Wear and Friction Laws on the Atomic Length Scale.

    PubMed

    Eder, S J; Feldbauer, G; Bianchi, D; Cihak-Bayr, U; Betz, G; Vernes, A

    2015-07-10

    Using molecular dynamics, we simulate the abrasion process of an atomically rough Fe surface with multiple hard abrasive particles. By quantifying the nanoscopic wear depth in a time-resolved fashion, we show that Barwell's macroscopic wear law can be applied at the atomic scale. We find that in this multiasperity contact system, the Bowden-Tabor term, which describes the friction force as a function of the real nanoscopic contact area, can predict the kinetic friction even when wear is involved. From this the Derjaguin-Amontons-Coulomb friction law can be recovered, since we observe a linear dependence of the contact area on the applied load in accordance with Greenwood-Williamson contact mechanics.

  10. Applications of Laser Cladded WC-Based Wear Resistant Coatings

    NASA Astrophysics Data System (ADS)

    Verwimp, Jo; Rombouts, Marleen; Geerinckx, Eric; Motmans, Filip

    Laser cladding is an additive process wherein a laser source is used to melt metal-based powder or wire on to a metal substrate. The technique is frequently used to produce wear resistant coatings consisting of a metal matrix and a ceramic strengthening phase. In this study mixtures of nickel based powders and various amounts of tungsten carbides have been used as feedstock for laser cladding on a range of steel substrates and for different applications. Crack-free low porosity coatings with a thickness of about 1 mm and carbide concentrations up to 50 vol% have been produced. The evaluation of the wear resistance of the different coatings is performed on lab scale or in the application itself.

  11. Structure characterization and wear performance of NiTi thermal sprayed coatings

    NASA Astrophysics Data System (ADS)

    Cinca, N.; Isalgué, A.; Fernández, J.; Guilemany, J. M.

    2010-08-01

    NiTi shape memory alloy (SMA) has been studied for many years for its shape memory and pseudoelastic properties, as well as its biocompatibility, which make it suitable for many biomedical applications. However, SMA NiTi is also interesting for relevant wear resistance near the transition temperature which, along with its high oxidation and corrosion resistance, suggests its use as a coating to increase the lifetime of some components. Also, whereas bulk material properties have been characterized in respect of the nominal composition, manufacturing methods and thermo-mechanical treatments, NiTi overlays have been investigated much less. Most existent works in this field specifically deal with magnetron sputtering technology for thin films and its use in micro-devices (micro-electro-mechanical systems, MEMS), just some works refer to vacuum plasma spraying (VPS) for thicker coatings. The present paper explores and compares the microstructure and wear-related properties of coatings obtained from atomized NiTi powders, by VPS as well as by atmospheric plasma spraying (APS) and high velocity oxygen fuel (HVOF) techniques. In the present case, the wear behaviour of the NiTi deposits has been studied by rubber-wheel equipment and ball-on-disk tests. The results obtained at room temperature show that the APS-quenched coatings exhibit a preferential dry sliding wear mechanism, while the VPS and HVOF coatings show an abrasive mechanism.

  12. Influence of the antagonist material on the wear of different composites using two different wear simulation methods.

    PubMed

    Heintze, S D; Zellweger, G; Cavalleri, A; Ferracane, J

    2006-02-01

    The aim of the study was to evaluate two ceramic materials as possible substitutes for enamel using two wear simulation methods, and to compare both methods with regard to the wear results for different materials. Flat specimens (OHSU n=6, Ivoclar n=8) of one compomer and three composite materials (Dyract AP, Tetric Ceram, Z250, experimental composite) were fabricated and subjected to wear using two different wear testing methods and two pressable ceramic materials as stylus (Empress, experimental ceramic). For the OHSU method, enamel styli of the same dimensions as the ceramic stylus were fabricated additionally. Both wear testing methods differ with regard to loading force, lateral movement of stylus, stylus dimension, number of cycles, thermocycling and abrasive medium. In the OHSU method, the wear facets (mean vertical loss) were measured using a contact profilometer, while in the Ivoclar method (maximal vertical loss) a laser scanner was used for this purpose. Additionally, the vertical loss of the ceramic stylus was quantified for the Ivoclar method. The results obtained from each method were compared by ANOVA and Tukey's test (p<0.05). To compare both wear methods, the log-transformed data were used to establish relative ranks between material/stylus combinations and assessed by applying the Pearson correlation coefficient. The experimental ceramic material generated significantly less wear in Tetric Ceram and Z250 specimens compared to the Empress stylus in the Ivoclar method, whereas with the OHSU method, no difference between the two ceramic antagonists was found with regard to abrasion or attrition. The wear generated by the enamel stylus was not statistically different from that generated by the other two ceramic materials in the OHSU method. With the Ivoclar method, wear of the ceramic stylus was only statistically different when in contact with Tetric Ceram. There was a close correlation between the attrition wear of the OHSU and the wear of the

  13. Damage tolerant functionally graded materials for advanced wear and friction applications

    NASA Astrophysics Data System (ADS)

    Prchlik, Lubos

    The research work presented in this dissertation focused on processing effects, microstructure development, characterization and performance evaluation of composite and graded coatings used for friction and wear control. The following issues were addressed. (1) Definition of prerequisites for a successful composite and graded coating formation by means of thermal spraying. (2) Improvement of characterization methods available for homogenous thermally sprayed coating and their extension to composite and graded materials. (3) Development of novel characterization methods specifically for FGMs, with a focus on through thickness property measurement by indentation and in-situ curvature techniques. (4) Design of composite materials with improved properties compared to homogenous coatings. (5) Fabrication and performance assessment of FGM with improved wear and impact damage properties. Materials. The materials studied included several material systems relevant to low friction and contact damage tolerant applications: MO-Mo2C, WC-Co cermets as materials commonly used sliding components of industrial machinery and NiCrAlY/8%-Yttria Partially Stabilized Zirconia composites as a potential solution for abradable sections of gas turbines and aircraft engines. In addition, uniform coatings such as molybdenum and Ni5%Al alloy were evaluated as model system to assess the influence of microstructure variation onto the mechanical property and wear response. Methods. The contact response of the materials was investigated through several techniques. These included methods evaluating the relevant intrinsic coating properties such as elastic modulus, residual stress, fracture toughness, scratch resistance and tests measuring the abrasion and friction-sliding behavior. Dry-sand and wet two-body abrasion testing was performed in addition to traditional ball on disc sliding tests. Among all characterization techniques the spherical indentation deserved most attention and enabled to

  14. High temperature resistant cermet and ceramic compositions. [for thermal resistant insulators and refractory coatings

    NASA Technical Reports Server (NTRS)

    Phillips, W. M. (Inventor)

    1978-01-01

    High temperature oxidation resistance, high hardness and high abrasion and wear resistance are properties of cermet compositions particularly to provide high temperature resistant refractory coatings on metal substrates, for use as electrical insulation seals for thermionic converters. The compositions comprise a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride are also described.

  15. Wear Resistant Coatings for Titanium.

    DTIC Science & Technology

    1980-10-01

    A-AllI 716 PRATT AND WHITNEY AIRCRAFT GROUP WEST PALM BEACH FL O-ETC P/f 11/6 WEAR RESISTANT COATINGS FOR TITANI WI.(U) OCT GO P L MCDANIEL, R E...treat cycle should be com- patible with previous heat-treat history and selected in accordance with MIL-H-81200. 11. (Option) - Vapor blast surfaces. 27...heat-treat history of the base metal and selected in accordance with MIL-H-81200 unless otherwise specified (see 6.2). Titanium alloys not covered by

  16. Fractographic and three body abrasion behaviour of Al-Garnet-C hybrid chill cast composites

    NASA Astrophysics Data System (ADS)

    Bandekar, Nityanand; Prasad, M. G. Anantha

    2017-08-01

    Fractographic and tribological behaviour of hybrid composite of aluminum alloy LM13 matrix with garnet and carbon was investigated. Conventional stir casting technique was used to fabricate the composites with chill cast technique. Various chill materials like Copper, Steel, Iron and Silicon carbide were used to improve the directional solidification. The garnet being added ranges from 3 to 12 wt-% in steps of 3wt-% and constant 3wt-% of carbon. The experiment evaluates the mechanical, fractographic and three body abrasion behaviour of the hybrid composites for various parameters of load, garnet and chills. Microstructural characterization of the composite samples revealed a uniform distribution of reinforcements with minimum clustering. SEM was used for examine worn surfaces. The addition of garnet and carbon reinforcement decreases the wear rate of hybrid composites. Fracture behaviour showed the changes from ductile mode to brittle mode of failure. Further, directional chilling with copper chill improves the wear resistance of the composites.

  17. Features of Wear-Resistant Cast Iron Coating Formation During Plasma-Powder Surfacing

    NASA Astrophysics Data System (ADS)

    Vdovin, K. N.; Emelyushin, A. N.; Nefed'ev, S. P.

    2017-09-01

    The structure of coatings deposited on steel 45 by plasma-powder surfacing of white wear-resistant cast iron is studied. The effects of surfacing regime and additional production effects on the welding bath during surfacing produced by current modulation, accelerated cooling of the deposited beads by blowing with air, and accelerated cooling of the substrate with running water on the structure, are determined. A new composition is suggested for powder material for depositing wear-resistant and corrosion-resistant coatings on a carbon steel by the plasma-powder process.

  18. The lexicon of polyethylene wear in artificial joints.

    PubMed

    McKellop, Harry A

    2007-12-01

    The analysis of wear on polyethylene components that have been retrieved after use in patients has provided invaluable understanding of how wear occurs in vivo, and how it may be minimized through improved materials and implant design. The great number of such studies that have been published over the past three decades has lead to an extensive vocabulary to describe the tribology of prosthetic joints. However, these also have led to some confusion, due to the occasional misuse of terms from classical tribology, along with the use of multiple terms to describe the same wear phenomenon, and vice versa. The author has proposed that our understanding of wear in artificial joints may be enhanced by recognizing that there are four general subject areas: Modes, Mechanisms, Damage and Debris. Wear Mode 1 occurs when the two bearing surfaces are articulating against each other in the manner intended by the implant designer. Mode 2 occurs when a bearing surface articulates against a non-bearing surface. Mode 3 occurs when third-body abrasive particles have become entrapped between the two bearing surfaces, and Mode 4 occurs when two non-bearing surfaces are wearing against each other. The least wear occurs in Mode 1, whereas severe wear typically occurs in Modes 2, 3 and 4. The classical wear mechanisms that apply to prosthetic joints include adhesion, abrasion and fatigue. These can occur in varying amounts in either of the four wear modes. As used in the literature for the past three decades, wear "damage" can best be defined as the change surface texture or morphology that is caused by the action of the wear mechanisms. Although a wide variety of terms have been used, an overview of the literature indicates that about eight terms have been sufficient to describe the types of damage that occur on retrieved polyethylene components, i.e., burnishing, abrasion, scratches, plastic deformation, cracks, pits, delamination, and embedded third bodies. The author suggests that, as

  19. The effect of boriding on wear resistance of cold work tool steel

    NASA Astrophysics Data System (ADS)

    Anzawa, Y.; Koyama, S.; Shohji, I.

    2017-05-01

    Recently, boriding has attracted extensive attention as surface stiffening processing of plain steel. In this research, the influence of processing time on the formation layer of cold work tool steel (KD11MAX) by Al added fused salt bath was examined. In addition, in order to improve the abrasion resistance of KD11MAX, the effect of the treatment of boronization on the formation layer has been investigated. Boriding were performed in molten borax which contained about 10 mass% Al at processing time of 1.8 ~ 7.2 ks (processing temperature of 1303 K). As a result of the examination, the hardness of the boriding layer becomes about 1900 HV when the processing time of 3.6 ks. Also the abrasion resistance has improved remarkably. Furthermore, it was revealed that the formation layer was boronized iron from the Vickers hardness and analysis of the X-ray diffraction measurement.

  20. Friction and wear behavior of aluminum and composite airplane skins

    NASA Technical Reports Server (NTRS)

    Jackson, K. E.

    1984-01-01

    Friction and wear behavior was determined for small skin specimens under abrasive loading conditions typical of those occurring on the underside of a transport airplane during emergency belly landing. A test apparatus consisting of a standard belt sander provided the sliding surface. Small test specimens constructed of aluminum, standard graphite-epoxy composite, aramid-epoxy composite, and toughened-resin composites were tested undar a range of pressures, belt velocities, and belt-surface textures. The effects of these test variables on the wear rate and the coefficient of friction are discussed and comparisons are made between the composite materials and aluminum. The effect of fiber orientation in the composite materials on wear rate was also investigated. In addition, tests were performed in which thermocouples were imbedded into the various test specimens to obtain temperature-time histories during abrasion.

  1. Investigation of wear land and rate of locally made HSS cutting tool

    NASA Astrophysics Data System (ADS)

    Afolalu, S. A.; Abioye, A. A.; Dirisu, J. O.; Okokpujie, I. P.; Ajayi, O. O.; Adetunji, O. R.

    2018-04-01

    Production technology and machining are inseparable with cutting operation playing important roles. Investigation of wear land and rate of cutting tool developed locally (C=0.56%) with an HSS cutting tool (C=0.65%) as a control was carried out. Wear rate test was carried out using Rotopol -V and Impact tester. The samples (12) of locally made cutting tools and one (1) sample of a control HSS cutting tool were weighed to get the initial weight and grit was fixed at a point for the sample to revolve at a specific time of 10 mins interval. Approach of macro transfer particles that involved mechanism of abrasion and adhesion which was termed as mechanical wear to handle abrasion adhesion processes was used in developing equation for growth wear at flank. It was observed from the wear test that best minimum wear rate of 1.09 × 10-8 and 2.053 × 10-8 for the tools developed and control were measured. MATLAB was used to simulate the wear land and rate under different conditions. Validated results of both the experimental and modeling showed that cutting speed has effect on wear rate while cutting time has predicted measure on wear land. Both experimental and modeling result showed best performances of tools developed over the control.

  2. [Tooth wear, a proposal for an evaluation system].

    PubMed

    Wetselaar, P; van der Zaag, J; Lobbezoo, F

    2011-06-01

    The present-day terminology and definitions of tooth wear are not unambiguous. For diagnosing tooth wear, however, it is essential that they are unambiguous. In this article a proposal is presented for a tooth wear evaluation system with simplified definitions. This system consists ofa number of modules and can be used for various aspects of the diagnostic procedure. It can be used for the quantification of tooth wear, both for periodic screening and for the monitoring of tooth wear in individual patients. The scoring of occlusal/incisal tooth wear as well as of non-occlusal/non-incisal tooth wear is possible. The evaluative system is also suitable for determining which type of tooth wear, such as attrition, abrasion and erosion, is most likely to have caused any observed loss of hard tooth tissue.

  3. Preparation of Polyurethane/Graphite Composite Films with Stable Mechanical Property and Wear Resistance Underwater.

    PubMed

    Wang, Miaomiao; Wang, Zubin; Chen, Qirong; Meng, Xiangfu; Heng, Liping

    2018-06-01

    The wear resistance and stable mechanical properties affect the service life of the underwater functional materials to a certain extent. Unfortunately, the current study of underwater functional materials is rarely related to these aspects. Herein, we successfully designed and prepared polyurethane/graphite nanosheet (PU/GN) composite materials, which exhibited excellent wear resistance and stable mechanical properties underwater. The PU/GN composite films were prepared by evaporating a mixed solution of PU and GN on concave hexagonal honeycomb silicon templates. The mechanical properties of the composite films were determined by tensile test, and the wear resistance was evaluated by comparing the surface morphology before and after grind. By adjusting the content of graphite in the composite films, we found that the composite films containing 23 wt% GN had higher tensile strength and superior wear resistance. Moreover, this composite film showed an outstanding stability when expose to water. The impressive results along with simple preparation process made PU/GN composite films had potential applications in robust underwater functional materials.

  4. Competing mechanisms in the wear resistance behavior of biomineralized rod-like microstructures

    NASA Astrophysics Data System (ADS)

    Escobar de Obaldia, Enrique; Herrera, Steven; Grunenfelder, Lessa Kay; Kisailus, David; Zavattieri, Pablo

    2016-11-01

    The remarkable mechanical properties observed in biological composite materials relative to those of their individual constituents distinguish them from common engineering materials. Some naturally occurring high-performance ceramics, like the external veneer of the Chiton (Cryptochiton stelleri) tooth, have been shown to have superior hardness and impressive abrasion resistance properties. The mechanical performance of the chiton tooth has been attributed to a hierarchical arrangement of nanostructured magnetite rods surrounded with organic material. While nanoindentation tests provide useful information about the overall performance of this biological composite, understanding the key microstructural features and energy dissipation mechanisms at small scales remains a challenging task. We present a combined experimental/numerical approach to elucidate the role of material deformation in the rods, debonding at the rod interfaces and the influence of energy dissipation mechanisms on the ability of the microstructure to distribute damage under extreme loading conditions. We employ a 3D finite element-based micromechanical model to simulate the nanoindentation tests performed in geological magnetite and cross-sections of the chiton tooth. This proposed model is capable of capturing the inelastic deformation of the rods and the failure of their interfaces, while damage, fracture and fragmentation of the mineralized rods is assessed using a probabilistic function. Our results show that these natural materials achieve their abrasion resistant properties by controlling the interface strength between rods, alleviating the tensile stress on the rods near the indentation tip and therefore decreasing the probability of catastrophic failure without significantly sacrificing resistance to penetration. The understanding of these competing energy dissipating mechanisms provides a path to the prediction of new combination of materials. In turns, these results suggest certain

  5. Investigation on the Tribological Behavior and Wear Mechanism of Five Different Veneering Porcelains

    PubMed Central

    Min, Jie; Zhang, Qianqian; Qiu, Xiaoli; Zhu, Minhao; Yu, Haiyang; Gao, Shanshan

    2015-01-01

    Objectives The primary aim of this research was to investigate the wear behavior and wear mechanism of five different veneering porcelains. Methods Five kinds of veneering porcelains were selected in this research. The surface microhardness of all the samples was measured with a microhardness tester. Wear tests were performed on a ball-on-flat PLINT fretting wear machine, with lubrication of artificial saliva at 37°C. The friction coefficients were recorded by the testing system. The microstructure features, wear volume, and damage morphologies were recorded and analyzed with a confocal laser scanning microscope and a scanning electron microscope. The wear mechanism was then elucidated. Results The friction coefficients of the five veneering porcelains differ significantly. No significant correlation between hardness and wear volume was found for these veneering porcelains. Under lubrication of artificial saliva, the porcelain with higher leucite crystal content exhibited greater wear resistance. Additionally, leucite crystal size and distribution in glass matrix influenced wear behavior. The wear mechanisms for these porcelains were similar: abrasive wear dominates the early stage, whereas delamination was the main damage mode at the later stage. Furthermore, delamination was more prominent for porcelains with larger crystal sizes. Significance Wear compatibility between porcelain and natural teeth is important for dental restorative materials. Investigation on crystal content, size, and distribution in glass matrix can provide insight for the selection of dental porcelains in clinical settings. PMID:26368532

  6. Aligned composite structures for mitigation of impact damage and resistance to wear in dynamic environments

    DOEpatents

    Mulligan, Anthony C.; Rigali, Mark J.; Sutaria, Manish P.; Popovich, Dragan; Halloran, Joseph P.; Fulcher, Michael L.; Cook, Randy C.

    2005-12-13

    Fibrous monolith composites having architectures that provide increased flaw insensitivity, improved hardness, wear resistance and damage tolerance and methods of manufacture thereof are provided for use in dynamic environments to mitigate impact damage and increase wear resistance.

  7. Aligned composite structures for mitigation of impact damage and resistance to wear in dynamic environments

    DOEpatents

    Mulligan, Anthony C.; Rigali, Mark J.; Sutaria, Manish P.; Popovich, Dragan; Halloran, Joseph P.; Fulcher, Michael L.; Cook, Randy C.

    2009-04-14

    Fibrous monolith composites having architectures that provide increased flaw insensitivity, improved hardness, wear resistance and damage tolerance and methods of manufacture thereof are provided for use in dynamic environments to mitigate impact damage and increase wear resistance.

  8. Aligned composite structures for mitigation of impact damage and resistance to wear in dynamic environments

    DOEpatents

    Rigali, Mark J.; Sutaria, Manish P.; Mulligan, Anthony C.; Popovich, Dragan

    2004-03-23

    Fibrous monolith composites having architectures that provide increased flaw insensitivity, improved hardness, wear resistance and damage tolerance and methods of manufacture thereof are provided for use in dynamic environments to mitigate impact damage and increase wear resistance.

  9. Study on torsional fretting wear behavior of a ball-on-socket contact configuration simulating an artificial cervical disk.

    PubMed

    Wang, Song; Wang, Fei; Liao, Zhenhua; Wang, Qingliang; Liu, Yuhong; Liu, Weiqiang

    2015-10-01

    A ball-on-socket contact configuration was designed to simulate an artificial cervical disk in structure. UHMWPE (ultra high molecular weight polyethylene) hot pressed by powders and Ti6Al4V alloy were selected as the material combination of ball and socket. The socket surface was coated by a ~500 nm C-DLC (carbon ion implantation-diamond like carbon) mixed layer to improve its surface nano hardness and wear resistance. The torsional fretting wear behavior of the ball-on-socket model was tested at different angular displacements under 25% bovine serum lubrication with an axial force of 100 N to obtain more realistic results with that in vivo. The fretting running regimes and wear damage characteristics as well as wear mechanisms for both ball and socket were studied based on 2D (two dimension) optical microscope, SEM (scanning electron microscope) and 3D (three dimension) profiles. With the increase of angular displacement amplitude from 1° to 7°, three types of T-θ (Torsional torque-angular displacement amplitude) curves (i.e., linear, elliptical and parallelogram loops) corresponding to running regimes of PSR (partial slip regime), MR (mixed regime) and SR (slip regime) were observed and analyzed. Both the central region and the edge zone of the ball and socket were damaged. The worn surfaces were characterized by wear scratches and wear debris. In addition, more severe wear damage and more wear debris appeared on the central region of the socket at higher angular displacement amplitude. The dominant damage mechanism was a mix of surface scratch, adhesive wear and abrasive wear for the UHMWPE ball while that for the coated socket was abrasive wear by PE particles and some polishing and rolling process on the raised overgrown DLC grains. The frictional kinetic behavior, wear type, damage region and damage mechanism for the ball-on-socket model revealed significant differences with those of a ball-on-flat contact while showing better consistency with that of in

  10. Ceramic roadway aggregates with improved polish- and wear-resistance

    DOT National Transportation Integrated Search

    1981-08-01

    Through a cooperative program between the Bureau of Mines, Tuscaloosa Research Center and the Federal Highway Administration, synthetic ceramic aggregates having high wear- and polish-resistance were developed. Three hundred aggregate compositions, i...

  11. Dentifrice fluoride and abrasivity interplay on artificial caries lesions.

    PubMed

    Nassar, Hani M; Lippert, Frank; Eckert, George J; Hara, Anderson T

    2014-01-01

    Incipient caries lesions on smooth surfaces may be subjected to toothbrushing, potentially leading to remineralization and/or abrasive wear. The interplay of dentifrice abrasivity and fluoride on this process is largely unknown and was investigated on three artificially created lesions with different mineral content/distribution. 120 bovine enamel specimens were randomly allocated to 12 groups (n = 10), resulting from the association of (1) lesion type [methylcellulose acid gel (MeC); carboxymethylcellulose solution (CMC); hydroxyethylcellulose gel (HEC)], (2) slurry abrasive level [low (REA 4/ RDA 69); high (REA 7/RDA 208)], and (3) fluoride concentration [0/275 ppm (14.5 mM) F as NaF]. After lesion creation, specimens were brushed in an automated brushing machine with the test slurries (50 strokes 2×/day). Specimens were kept in artificial saliva in between brushings and overnight. Enamel surface loss (SL) was determined by optical profilometry after lesion creation, 1, 3 and 5 days. Two enamel sections (from baseline and post-brushing areas) were obtained and analyzed microradiographically. Data were analyzed by analysis of variance and Tukey's tests (α = 5%). Brushing with high-abrasive slurry caused more SL than brushing with low-abrasive slurry. For MeC and CMC lesions, fluoride had a protective effect on SL from day 3 on. Furthermore, for MeC and CMC, there was a significant mineral gain in the remaining lesions except when brushed with high-abrasive slurries and 0 ppm F. For HEC, a significant mineral gain took place when low-abrasive slurry was used with fluoride. The tested lesions responded differently to the toothbrushing procedures. Both slurry fluoride content and abrasivity directly impacted SL and mineral gain of enamel caries lesions.

  12. Toothbrush abrasion, simulated tongue friction and attrition of eroded bovine enamel in vitro.

    PubMed

    Vieira, A; Overweg, E; Ruben, J L; Huysmans, M C D N J M

    2006-05-01

    Enamel erosion results in the formation of a softened layer that is susceptible to disruption by mechanical factors such as brushing abrasion, tongue friction and attrition. The aim of this study was to investigate the individual contribution of those mechanical insults to the enamel loss caused by dental erosion. Forty two bovine enamel samples were randomly divided into seven groups (n=6 per group) that were submitted to 3cycles of one of the following regimes: erosion and remineralization (er/remin); toothbrush abrasion and remineralization (abr/remin); erosion, toothbrush abrasion and remineralization (er/abr/remin); attrition and remineralization (at/remin); erosion, attrition and remineralization (er/at/remin); simulated tongue friction and remineralization (tg/remin); erosion, simulated tongue friction and remineralization (er/tg/remin). Erosion took place in a demineralization solution (50mM citric acid, pH 3) for 10min under agitation. Brushing abrasion, tongue friction and attrition were simulated for 1min using a home-made wear device. Remineralization was carried out in artificial saliva for 2h. Enamel loss was quantified using optical profilometry. One-way ANOVA indicated a significant difference between the amounts of enamel lost due to the different wear regimes (pwear depths found for the er/at/remin (p

  13. Wear characteristics of current aesthetic dental restorative CAD/CAM materials: two-body wear, gloss retention, roughness and Martens hardness.

    PubMed

    Mörmann, Werner H; Stawarczyk, Bogna; Ender, Andreas; Sener, Beatrice; Attin, Thomas; Mehl, Albert

    2013-04-01

    This study determined the two-body wear and toothbrushing wear parameters, including gloss and roughness measurements and additionally Martens hardness, of nine aesthetic CAD/CAM materials, one direct resin-based nanocomposite plus that of human enamel as a control group. Two-body wear was investigated in a computer-controlled chewing simulator (1.2 million loadings, 49N at 1.7Hz; 3000 thermocycles 5/50°C). Each of the 11 groups consisted of 12 specimens and 12 enamel antagonists. Quantitative analysis of wear was carried out with a 3D-surface analyser. Gloss and roughness measurements were evaluated using a glossmeter and an inductive surface profilometer before and after abrasive toothbrushing of machine-polished specimens. Additionally Martens hardness was measured. Statistically significant differences were calculated with one-way ANOVA (analysis of variance). Statistically significant differences were found for two-body wear, gloss, surface roughness and hardness. Zirconium dioxide ceramics showed no material wear and low wear of the enamel antagonist. Two-body wear of CAD/CAM-silicate and -lithium disilicate ceramics, -hybrid ceramics and -nanocomposite as well as direct nanocomposite did not differ significantly from that of human enamel. Temporary polymers showed significantly higher material wear than permanent materials. Abrasive toothbrushing significantly reduced gloss and increased roughness of all materials except zirconium dioxide ceramics. Gloss retention was highest with zirconium dioxide ceramics, silicate ceramics, hybrid ceramics and nanocomposites. Temporary polymers showed least gloss retention. Martens hardness differed significantly among ceramics, between ceramics and composites, and between resin composites and acrylic block materials as well. All permanent aesthetic CAD/CAM block materials tested behave similarly or better with respect to two-body wear and toothbrushing wear than human enamel, which is not true for temporary polymer CAD

  14. Effect of dried sunflower seeds on incisal edge abrasion: A rare case report.

    PubMed

    Rath, Avita; Ramamurthy, Priyadarshini H; Fernandes, Bennete Aloysius; Sidhu, Preena

    2017-01-01

    Tooth surface loss (TSL) is a complex phenomenon characterized by the loss of hard tooth structure at various locations of the teeth, usually due to more than one factor. TSL due to abrasion can be significant in patients consuming coarse, abrasive diet. The present case reports an interesting incisal edge abrasion in a female patient, attributed to a particular dietary behavior of long-term consumption of sunflower seeds. All her family members and most of the people from her native place were also reported to have similar lesions by the patient. Larger epidemiological studies to assess the prevalence and severity of such abrasive lesions in geographic areas with this particular dietary habit need to be carried out so that people may be made aware and educated about alternative ways of eating sunflower seeds that will not cause any form of tooth wear.

  15. Abrasion of Candidate Spacesuit Fabrics by Simulated Lunar Dust

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Meador, Mary Ann; Rogers, Kerry J.; Sheehy, Brennan H.

    2009-01-01

    A protocol has been developed that produced the type of lunar soil abrasion damage observed on Apollo spacesuits. This protocol was then applied to four materials (Kevlar (DuPont), Vectran (Kuraray Co., Ltd.), Orthofabric, and Tyvek (DuPont)) that are candidates for advanced spacesuits. Three of the four new candidate fabrics (all but Vectran) were effective at keeping the dust from penetrating to layers beneath. In the cases of Kevlar and Orthofabric this was accomplished by the addition of a silicone layer. In the case of Tyvek, the paper structure was dense enough to block dust transport. The least abrasive damage was suffered by the Tyvek. This was thought to be due in large part to its non-woven paper structure. The woven structures were all abraded where the top of the weave was struck by the abrasive. Of these, the Orthofabric suffered the least wear, with both Vectran and Kevlar suffering considerably more extensive filament breakage.

  16. Baking soda as an abrasive in toothpastes: Mechanism of action and safety and effectiveness considerations.

    PubMed

    Hara, Anderson T; Turssi, Cecilia P

    2017-11-01

    Toothpastes can be formulated with different abrasive systems, depending on their intended clinical application. This formulation potentially affects their effectiveness and safety and, therefore, requires proper understanding. In this article, the authors focused on abrasive aspects of toothpastes containing sodium bicarbonate (baking soda), which have gained considerable attention because of their low abrasivity and good compatibility, while providing clinical effectiveness (further detailed in the other articles of this special issue). The authors first appraised the role of toothpaste abrasivity on tooth wear, exploring some underlying processes and the existing methods to determine toothpaste abrasivity. The authors reviewed the available data on the abrasivity of toothpastes containing baking soda and reported a summary of findings highlighting the clinical implications. On the basis of the collected evidence, baking soda has an intrinsic low-abrasive nature because of its comparatively lower hardness in relation to enamel and dentin. Baking soda toothpastes also may contain other ingredients, which can increase their stain removal effectiveness and, consequently, abrasivity. Even those formulations have abrasivity well within the safety limit regulatory agencies have established and, therefore, can be considered safe. Copyright © 2017 American Dental Association. Published by Elsevier Inc. All rights reserved.

  17. Development of wear resistant ceramic coatings for diesel engine components

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Haselkorn, M.H.

    1992-04-01

    Improved fuel economy and a reduction of emissions can be achieved by insulation of the combustion chamber components to reduce heat rejection. However, insulating the combustion chamber components will also increase the operating temperature of the piston ring/cylinder liner interface from approximately 150{degree}C to over 300{degree}C. Existing ring/liner materials can not withstand these higher operating temperatures and for this reason, new materials need to be developed for this critical tribological interface. The overall goal of this program is the development of piston ring/cylinder liner material pairs which would be able to provide the required friction and wear properties at thesemore » more severe operating conditions. More specifically, this program first selected, and then evaluated, potential d/wear resistant coatings which could be applied to either piston rings an or cylinder liners and provide, at 350{degree}C under lubricated conditions, coefficients of friction below 0.1 and wear rates of less than 25 {times} lO{sup {minus}6} mm/hour. The processes selected for applying the candidate wear resistant coatings to piston rings and/or cylinder liners were plasma spraying, chemical vapor, physical vapor and low temperature arc vapor deposition techniques as well as enameling techniques.« less

  18. Wear resistance of four types of vacuum-formed retainer materials: a laboratory study.

    PubMed

    Raja, Taiyub A; Littlewood, Simon J; Munyombwe, Theresa; Bubb, Nigel L

    2014-07-01

    To investigate the resistance to wear of four different vacuum-formed retainer (VFR) materials: Essix C+, Essix ACE, Duran, and Tru-Tain. Essix C+ is a polypropylene polymer; the other materials are polyethylene co-polymers. The study was undertaken at the Leeds Dental Institute, Leeds, UK, with 26 samples in each group. The specimens were vacuum-formed according to the manufacturers' guidelines, and a custom-made wear-simulation machine was used to conduct the test. Each specimen was subjected to 1000 cycles of the wear simulation, with steatite balls as the antagonist material. The resistance to wear of the VFR materials was evaluated by measuring the maximum wear depth using noncontact, three-dimensional surface profilometry. The wear depth was given in micrometers. The median wear depth was 63.20 µm for the Essix C+ group, 7.88 µm for the Essix ACE group, 9.75 µm for the Duran group, and 12.08 µm for the Tru-Tain group. The Kruskal-Wallis test to compare the four VFR materials detected a statistically significant difference between the groups (P < .001). Comparisons of the groups using the Mann-Whitney U-test demonstrated that the Essix C+ group had significantly greater wear than the other three groups (P < .001). There was no statistically significant difference in median wear depth between the two groups with the least amount of wear-the Essix ACE and Duran groups. Under the standardized conditions of this laboratory study, the three polyethylene co-polymer materials-Essix ACE, Duran, and Tru-Tain-exhibited significantly less wear than the polypropylene material, Essix C+.

  19. Multi technical analysis of wear mechanisms in axial piston pumps

    NASA Astrophysics Data System (ADS)

    Schuhler, G.; Jourani, A.; Bouvier, S.; Perrochat, J.-M.

    2017-05-01

    Axial piston pumps convert a motor rotation motion into hydraulic or pneumatic power. Their compactness and efficiency of approximately 0.9 make them suitable for actuation applications especially in aeronautics. However, they suffer a limited life due to the wear of their components. In the literature, studies of axial piston pumps deal with contact between its different elements under lubrication conditions. Nevertheless, they are more focused on analytic or numerical approaches. This study consists in an experimental analysis of worn pump components to highlight and understand wear mechanisms. Piston shoes are central components in the axial piston pump since they are involved in three tribological contacts. These three contacts are thereby studied: piston shoes/swashplate, piston shoes/pistons and piston shoes/shoes hold down plate (SHDP). To perform this analysis, helicopter hydraulic pumps after different operating times have been studied. The wear damage mechanisms and wear debris are analysed using SEM observations. 3D surface roughness measurements are then used to characterize worn surfaces. The observations reveal that in the contact between shoes and swashplate, the main wear mechanism is three-body abrasive wear due to coarse carbides removal. Between shoes and pistons, wear occurs in a less severe way and is mainly due to the debris generated in the first contact and conveyed by the lubricating fluid. In the third contact, the debris are also the prime cause of the abrasive wear and the generation of deep craters in the piston shoes.

  20. Effect of Isothermal Bainitic Quenching on Rail Steel Impact Strength and Wear Resistance

    NASA Astrophysics Data System (ADS)

    Çakir, Fatih Hayati; Çelik, Osman Nuri

    2017-09-01

    The effect of heat treatment regimes on hardness, impact strength, and wear resistance of rail steel for high-speed tracks (rail quality category R350HT) is studied. Analysis of steel properties with a different structure is compared: pearlitic, and upper and lower bainite. It is shown that the steel with bainitic structure has the best impact strength, but wear resistance is better for steel with a lower bainite structure.

  1. Influences of die channel angles on microstructures and wear behaviors of AZ61 wrought magnesium alloy fabricated by extrusion-shear process

    NASA Astrophysics Data System (ADS)

    Hu, Hong-J.; Sun, Z.; Ou, Z.-W.

    2016-12-01

    Extrusion-shear (ES) process for magnesium alloy is a newly developed plastic deformation process, and ES process combines direct extrusion and two steps of ECAE (equal channel angular extrusion). To investigate the effects of the die channel angles on the microstructures and wear behaviors of AZ61 wrought magnesium alloy, the samples used in this study were fabricated by ES process with different die channel angles (120° and 135°). The microstructures of the samples were characterized by optical microscopy (OM), X-ray diffraction (XRD) and (SEM). The cumulative strains in the ES process were predicted by approaches of numerical simulation and theoretical calculation. To characterize the wear resistance of the samples, pin-on-disk tests under dry sliding conditions with various normal loads and reciprocating frequencies were conducted. To define the wear mechanisms of AZ61 magnesium alloy, the worn surfaces after wear tests were analyzed by SEM and energy-dispersive X-ray spectrometer (EDS). Based on the results obtained, die channel angles have significant influences on the grain refinements and wear behaviors of the samples. Decreasing channel angles of the ES die will not only refine the microstructures of magnesium alloys effectively and improve their harnesses, but also improve their wear resistance as decreasing channel angles results in higher friction coefficients and wear rates. With the increase in applied loads and frequencies, wear mechanisms change from mild wear (adhesion, abrasion and oxidation) to severe wear (delamination, plastic deformation and melting). In summary, the wear resistance of ES-processed AZ61 magnesium alloy could be improved by decreasing channel angles of ES dies.

  2. Fretting Wear Damage Mechanism of Uranium under Various Atmosphere and Vacuum Conditions

    PubMed Central

    Li, Zhengyang; Wu, Yanping; Meng, Xiandong; Zhang, Dongxu

    2018-01-01

    A fretting wear experiment with uranium has been performed on a linear reciprocating tribometer with ball-on-disk contact. This study focused on the fretting behavior of the uranium under different atmospheres (Ar, Air (21% O2 + 78% N2), and O2) and vacuum conditions (1.05 and 1 × 10−4 Pa). Evolution of friction was assessed by coefficient of friction (COF) and friction-dissipated energy. The oxide of the wear surface was evaluated by Raman spectroscopy. The result shows that fretting wear behavior presents strong atmosphere and vacuum condition dependence. With increasing oxygen content, the COF decreases due to abrasive wear and formation of oxide film. The COF in the oxygen condition is at least 0.335, and it has a maximum wear volume of about 1.48 × 107 μm3. However, the COF in a high vacuum condition is maximum about 1.104, and the wear volume is 1.64 × 106 μm3. The COF in the low vacuum condition is very different: it firstly increased and then decreased rapidly to a steady value. It is caused by slight abrasive wear and the formation of tribofilm after thousands of cycles. PMID:29659484

  3. Wear-resistant ball bearings for space applications

    NASA Technical Reports Server (NTRS)

    Boving, H.; Hintermann, H. E.; Hanni, W.; Bondivenne, E.; Boeto, M.; Conde, E.

    1977-01-01

    Ball bearings consisting of steel parts of which the rings are coated with hard, wear resistant, chemical vapor deposited TiC are described. Experiments conducted in ultrahigh vacuum, using cages of various materials with self-lubricating properties, show that such bearings are suitable for space applications. The results of laboratory tests on the ESA Meteosat Radiometer Focalizing mechanism, which contains six coated bearings, are summarized.

  4. Heat sealable, flame and abrasion resistant coated fabric. [clothing and containers for space exploration

    NASA Technical Reports Server (NTRS)

    Tschirch, R. P.; Sidman, K. R. (Inventor)

    1981-01-01

    Flame retardant, abrasion resistant elastomeric compositions are comprised of thermoplastic polyurethane polymer and flame retarding amounts of a filler selected from decabromodiphenyloxide and antimony oxide in a 3:1 weight ratio, and decabromodiphenyloxide, antimony oxide, and ammonium polyphosphate in a 3:1:3 weight ratio respectively. Coated fabrics employing such elastomeric compositions as coating film are flexible, lightweight, and air impermeable and can be made using heat or dielectric sealing procedures.

  5. Sustainable and long-time 'rejuvenation' of biomimetic water-repellent silica coating on polyester fabrics induced by rough mechanical abrasion.

    PubMed

    Rosu, Cornelia; Lin, Haisheng; Jiang, Lu; Breedveld, Victor; Hess, Dennis W

    2018-04-15

    The economical use of water-repellent coatings on polymeric materials in commercial and industrial applications is limited by their mechanical wear robustness and long-term durability. In this study, we demonstrate that polyethylene terephthalate (PET) fabric modified with inorganic, methyltrimethoxysilane (MTMS)-based coatings shows excellent resistance against various types of wear damage, thereby mimicking superhydrophobic biological materials. These features were facilitated by the rational design of coating processing that also enabled tunable hierarchical surface structure. A series of custom and standard testing protocols revealed that coating-to-substrate adhesion was remarkably high, as was the resistance to various mechanical abradents. The most intriguing characteristic observed during aging and abrasion cycles was the enhancement in non-wettability or 'rejuvenation' reflected by water droplet roll-off behavior, a characteristic of self-cleaning materials. Water-repellent properties of coated polyester were also enhanced by prolonged thermal annealing and were maintained after custom laundry. The developed technology offers opportunities to design low cost, durable and functional textiles for both indoor and outdoor applications. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. Inspection of wear particles in oils by using a fuzzy classifier

    NASA Astrophysics Data System (ADS)

    Hamalainen, Jari J.; Enwald, Petri

    1994-11-01

    The reliability of stand-alone machines and larger production units can be improved by automated condition monitoring. Analysis of wear particles in lubricating or hydraulic oils helps diagnosing the wear states of machine parts. This paper presents a computer vision system for automated classification of wear particles. Digitized images from experiments with a bearing test bench, a hydraulic system with an industrial company, and oil samples from different industrial sources were used for algorithm development and testing. The wear particles were divided into four classes indicating different wear mechanisms: cutting wear, fatigue wear, adhesive wear, and abrasive wear. The results showed that the fuzzy K-nearest neighbor classifier utilized gave the same distribution of wear particles as the classification by a human expert.

  7. Toughness of Wear-Resistant Cu-Zr-Based Bulk Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Andersen, Laura M.

    Bulk metallic glasses (BMGs) have the potential to exhibit exceptional wear-resistance due to their high hardness and strength. Combined with their other unique properties, this makes them ideal candidates for a wide range of technological applications (e.g. gears, bearings, biomaterials). In the course of this dissertation, high-glass-forming bulk metallic glasses are prepared and characterized in order to identify wear-resistant compositions and optimize their toughness. First, a comprehensive study identifies a class of Cu-Zr-based BMGs that exhibit more exceptional wear performance than other BMGs. The results demonstrate that when BMGs are designed properly, they exhibit wear properties that compete with, and can surpass, state-of-the-art engineering materials. It is identified that, in order to optimize the wear performance of Cu-Zr-based BMG gears, toughness should be maximized. Second, the notch toughness of wear-resistant Cu43Zr 43Al7Be7 BMGs with in-situ crystallization is investigated. In order to identify in-situ crystallization using X-ray diffraction (XRD) with Cu K? radiation, extremely long dwell times and high X-ray fluxes are required. This demonstrates the importance of reporting operating parameters when trying to evaluate the amorphous nature of BMGs. XRD, energy-dispersive X-ray spectroscopy (EDS) and electron backscatter diffraction (EBSD) are used to identify the metastable crystalline phase. The notch toughness is found to correlate closely with the amount of crystallization and the composition of the remaining amorphous matrix. Finally, the effect of substituting standard-grade zirconium lump (99.8% excluding up to 4% hafnium) for high-purity zirconium crystal bar (99.5%) in Cu43Zr43Al7Be7 is investigated. Introducing low-purity zirconium significantly decreases the glass-forming-ability and reduces the notch toughness of the BMG. Furthermore, Weibull statistics provide an analysis of the variability in toughness for high-purity ingots

  8. Dental wear, wear rate, and dental disease in the African apes.

    PubMed

    Elgart, Alison A

    2010-06-01

    The African apes possess thinner enamel than do other hominoids, and a certain amount of dentin exposure may be advantageous in the processing of tough diets eaten by Gorilla. Dental wear (attrition plus abrasion) that erodes the enamel exposes the underlying dentin and creates additional cutting edges at the dentin-enamel junction. Hypothetically, efficiency of food processing increases with junction formation until an optimal amount is reached, but excessive wear hinders efficient food processing and may lead to sickness, reduced fecundity, and death. Occlusal surfaces of molars and incisors in three populations each of Gorilla and Pan were videotaped and digitized. The quantity of incisal and molar occlusal dental wear and the lengths of dentin-enamel junctions were measured in 220 adult and 31 juvenile gorilla and chimpanzee skulls. Rates of dental wear were calculated in juveniles by scoring the degree of wear between adjacent molars M1 and M2. Differences were compared by principal (major) axis analysis. ANOVAs compared means of wear amounts. Pearson correlation coefficients were calculated to compare the relationship between molar wear and incidence of dental disease. Results indicate that quantities of wear are significantly greater in permanent incisors and molars and juvenile molars of gorillas compared to chimpanzees. The lengths of dentin-enamel junctions were predominantly suboptimal. Western lowland gorillas have the highest quantities of wear and the most molars with suboptimal wear. The highest rates of wear are seen in Pan paniscus and Pan t. troglodytes, and the lowest rates are found in P.t. schweinfurthii and G. g. graueri. Among gorillas, G. b. beringei have the highest rates but low amounts of wear. Coefficients between wear and dental disease were low, but significant when all teeth were combined. Gorilla teeth are durable, and wear does not lead to mechanical senescence in this sample.

  9. Tungsten coating for improved wear resistance and reliability of microelectromechanical devices

    DOEpatents

    Fleming, James G.; Mani, Seethambal S.; Sniegowski, Jeffry J.; Blewer, Robert S.

    2001-01-01

    A process is disclosed whereby a 5-50-nanometer-thick conformal tungsten coating can be formed over exposed semiconductor surfaces (e.g. silicon, germanium or silicon carbide) within a microelectromechanical (MEM) device for improved wear resistance and reliability. The tungsten coating is formed after cleaning the semiconductor surfaces to remove any organic material and oxide film from the surface. A final in situ cleaning step is performed by heating a substrate containing the MEM device to a temperature in the range of 200-600 .degree. C. in the presence of gaseous nitrogen trifluoride (NF.sub.3). The tungsten coating can then be formed by a chemical reaction between the semiconductor surfaces and tungsten hexafluoride (WF.sub.6) at an elevated temperature, preferably about 450.degree. C. The tungsten deposition process is self-limiting and covers all exposed semiconductor surfaces including surfaces in close contact. The present invention can be applied to many different types of MEM devices including microrelays, micromirrors and microengines. Additionally, the tungsten wear-resistant coating of the present invention can be used to enhance the hardness, wear resistance, electrical conductivity, optical reflectivity and chemical inertness of one or more semiconductor surfaces within a MEM device.

  10. Investigations of the effects of particle properties on the wear resistance of the particle reinforced composites using a novel wear model

    NASA Astrophysics Data System (ADS)

    Prabhu, T. Ram

    2016-08-01

    A wear model is developed based on the discrete lattice spring-mass approach to study the effects of particle volume fraction, size, and stiffness on the wear resistance of particle reinforced composites. To study these effects, we have considered three volume fractions (10%, 20% and 30%), two sizes (10 × 10 and 4 × 4 sites), and two different stiffness of particles embedded in the matrix in a regular pattern. In this model, we have discretized the composite system (400 × 100 sites) into the lumped masses connected with interaction spring elements in two dimensions. The interaction elements are assumed as linear elastic and ideal plastic under applied forces. Each mass is connected to its first and second nearest neighbors by springs. The matrix and particles sites are differentiated by choosing the different stiffness values. The counter surface is simulated as a rigid body that moves on the composite material at a constant sliding speed along the horizontal direction. The governing equations are formed by equating the spring force between the pair of sites given by Hooke’s law plus external contact forces and the force due to the motion of the site given by the equation of motion. The equations are solved for the plastic strain accumulated in the springs using an explicit time stepping procedure based on a finite difference form of the above equations. If the total strain accumulated in the spring elements connected to a lump mass site exceeds the failure strain, the springs are considered to be broken, and the mass site is removed or worn away from the lattice and accounts as a wear loss. The model predicts that (i) increasing volume fraction, reducing particle size and increasing particle stiffness enhance the wear resistance of the particle reinforced composites, (ii) the particle stiffness is the most significant factor affecting the wear resistance of the composites, and (iii) the wear resistance reduced above the critical volume fraction (Vc), and Vc

  11. High temperature resistant cermet and ceramic compositions

    NASA Technical Reports Server (NTRS)

    Phillips, W. M. (Inventor)

    1978-01-01

    Cermet compositions having high temperature oxidation resistance, high hardness and high abrasion and wear resistance, and particularly adapted for production of high temperature resistant cermet insulator bodies are presented. The compositions are comprised of a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Also disclosed are novel ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride.

  12. Optically transparent and durable Al2O3 coatings for harsh environments by ultra short pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Korhonen, Hannu; Syväluoto, Aki; Leskinen, Jari T. T.; Lappalainen, Reijo

    2018-01-01

    Nowadays, an environmental protection is needed for a number of optical applications in conditions quickly impairing the clarity of optical surfaces. Abrasion resistant optical coatings applied onto plastics are usually based on alumina or polysiloxane technology. In many applications transparent glasses and ceramics need a combination of abrasive and chemically resistant shielding or other protective solutions like coatings. In this study, we intended to test our hypothesis that clear and pore free alumina coating can be uniformly distributed on glass prisms by ultra short pulsed laser deposition (USPLD) technique to protect the sensitive surfaces against abrasives. Abrasive wear tests were carried out by the use of SiC emery paper using specified standard procedures. After the wear tests the measured transparencies of coated prisms turned out to be close those of the prisms before coating. The coating on sensitive surfaces consistently displayed enhanced wear resistance exhibiting still high quality, even after severe wear testing. Furthermore, the coating modified the surface properties towards hydrophobic nature in contrast to untreated prisms, which became very hydrophilic especially due to wear.

  13. Process for producing a well-adhered durable optical coating on an optical plastic substrate. [abrasion resistant polymethyl methacrylate lenses

    NASA Technical Reports Server (NTRS)

    Kubacki, R. M. (Inventor)

    1978-01-01

    A low temperature plasma polymerization process is described for applying an optical plastic substrate, such as a polymethyl methacrylate lens, with a single layer abrasive resistant coating to improve the durability of the plastic.

  14. Friction and wear properties of novel HDPE--HAp--Al2O3 biocomposites against alumina counterface.

    PubMed

    Bodhak, Subhadip; Nath, Shekhar; Basu, Bikramjit

    2009-03-01

    In an effort to enhance physical properties of biopolymers (high-density polyethylene, HDPE) in terms of elastic modulus and hardness, various ceramic fillers, like alumina (Al2O3) and hydroxyapatite (HAp) are added, and therefore it is essential to assess the friction and wear resistance properties of HDPE biocomposites. In this perspective, HDPE composites with varying ceramic filler content (upto 40 vol%) were fabricated under the optimal compression molding conditions and their friction and wear properties were evaluated against Al2O3 at fretting contacts. All the experiments were conducted at a load of 10 N for duration of 100,000 cycles in both dry as well as simulated body fluid (SBF). Such planned set of experiments has been designed to address three important issues: (a) whether the improvement in physical properties (hardness, E-modulus) will lead to corresponding improvement in friction and wear properties; (b) whether the fretting in SBF will provide sufficient lubrication in order to considerably enhance the tribological properties, as compared to that in ambient conditions; and (c) whether the generation of wear debris particles be reduced for various compositionally modified polymer composites, in comparison to unreinforced HDPE. The experimental results indicate the possibility of achieving extremely low coefficient of friction (COF approximately 0.047) as well as higher wear resistance (wear rate in the order of approximately 10(-7) mm3 N(-1) m(-1)) with the newly developed composites in SBF. A low wear depth of 3.5-4 microm is recorded, irrespective of fretting environment. Much effort has been put forward to correlate the friction and wear mechanisms with abrasion, adhesion, and wear debris formation.

  15. Wear resistance of a pressable low-fusing ceramic opposed by dental alloys.

    PubMed

    Faria, Adriana Cláudia Lapria; de Oliveira, André Almeida; Alves Gomes, Érica; Silveira Rodrigues, Renata Cristina; Faria Ribeiro, Ricardo

    2014-04-01

    Dental alloys have increasingly replaced by dental ceramics in dentistry because of aesthetics. As both dental alloys and ceramics can be present in the oral cavity, the evaluation of the wear resistance of ceramics opposed by dental alloys is important. The aim of the present study was to evaluate wear resistance of a pressable low-fusing ceramic opposed by dental alloys as well as the microhardness of the alloys and the possible correlation of wear and antagonist microhardness. Fifteen stylus tips samples of pressable low-fusing ceramic were obtained, polished and glazed. Samples were divided into three groups according to the disk of alloy/metal to be used as antagonist: Nickel-Chromium (Ni-Cr), Cobalt-Chromium (Co-Cr) and commercially pure titanium (cp Ti). Vickers microhardness of antagonist disks was evaluated before wear tests. Then, antagonist disks were sandblasted until surface roughness was adjusted to 0.75μm. Wear tests were performed at a speed of 60 cycles/min and distance of 10mm, in a total of 300,000 cycles. Before and after wear tests, samples were weighted and had their profile designed in an optical comparator to evaluate weight and height loss, respectively. Ni-Cr and cp Ti caused greater wear than Co-Cr, presenting greater weight (p=.009) and height (p=.002) loss. Cp Ti microhardness was lower than Ni-Cr and Co-Cr (p<.05). There is a positive correlation between weight and height loss (p<.05), but weight (p=.204) and height (p=.05) loss are not correlated to microhardness. The results suggest that pressable low-fusing ceramic presents different wear according to the dental alloy used as antagonist and the wear is not affected by antagonist microhardness. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. A fundamental review of the friction and wear behavior of ceramics

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1972-01-01

    The basic concepts associated with the friction and wear of materials are discussed as they relate to ceramics. Properties of ceramics such as crystal structure, crystallographic orientation, mechanical deformation, and surface chemistry are reviewed as they influence friction and wear. Both adhesive and abrasive wear of ceramics are discussed. The friction and wear of ceramics are examined in contact with themselves and when in contact with metals. The influences of environmental constituents such as water and hydrocarbons on friction and wear are reviewed. Materials discussed, by way of example, include aluminum oxide, rutile, calcium fluoride, and lithium fluoride.

  17. [Influence of multiple sintering on wear behavior of Cercon veneering ceramic].

    PubMed

    Gao, Qing-ping; Chao, Yong-lie; Jian, Xin-chun; Guo, Feng

    2010-04-01

    To investigate the influence of multiple sintering on wear behavior of Cercon veneering ceramic. Samples were fabricated according to the manufacture's requirement for different sintering times (1, 3, 5, 7 times). The wear test was operated with a modified MM-200 friction and wear machine in vitro. The wear scars were characterized by scanning electron microscope (SEM) and atomic force microscopy (AFM). With the sintering times increasing, the wear scar width became larger. The correlation was significant at the 0.01 level. Significant difference was observed in wear scar width among different samples (P < 0.05). SEM and AFM results showed that veneering ceramic wear facets demonstrated grooves characteristic of abrasive wear. Multiple sintering can decrease the wear ability of Cercon veneer, and the wear pattern has the tendency to severe wear.

  18. Microstructure and corrosive wear resistance of plasma sprayed Ni-based coatings after TIG remelting

    NASA Astrophysics Data System (ADS)

    Tianshun, Dong; Xiukai, Zhou; Guolu, Li; Li, Liu; Ran, Wang

    2018-02-01

    Ni based coatings were prepared on steel substrate by means of plasma spraying, and were remelted by TIG (tungsten inert gas arc) method subsequently. The microstructure, microhardness, electrochemical corrosion and corrosive wear resistance under PH = 4, PH = 7 and PH = 10 conditions of the coatings before and after remelting were investigated. The results showed that the TIG remelting obviously reduced the defects and dramatically decreased the coating’s porosity from 7.2% to 0.4%. Metallurgical bonding between the remelted coating and substrate was achieved. Meanwhile, the phase compositions of as-sprayed coating were γ-Ni, Mn5Si2 and Cr2B, while the phase compositions of the remelting coating were Fe3Ni, Cr23C6, Cr2B and Mn5Si2. The microhardness of the coating decreased from 724 HV to 608 HV, but the fracture toughness enhanced from 2.80 MPa m1/2 to 197.3 MPa m1/2 after remelting. After corrosive wear test, the average wear weight loss and 3D morphology of wear scar of two coatings indicated that the wear resistance of the remelted coating was remarkably higher than that of as-sprayed coating. Therefore, TIG remelting treatment was a feasible method to improve the coating’s microstructure and enhance its corrosive wear resistance.

  19. Strength and wear resistance of a dental glass-ionomer cement with a novel nanofilled resin coating.

    PubMed

    Lohbauer, Ulrich; Krämer, Norbert; Siedschlag, Gustavo; Schubert, Edward W; Lauerer, Brigitte; Müller, Frank A; Petschelt, Anselm; Ebert, Johannes

    2011-04-01

    To evaluate the influence of different resin coating protocols on the fracture strength and wear resistance of a commercial glass-ionomer cement (GIC). A new restorative concept [Equia (GC Europe)] has been introduced as a system application consisting of a condensable GIC (Fuji IX GP Extra) and a novel nanofilled resin coating material (G-Coat Plus). Four-point fracture strength (FS, 2 x 2 x 25 mm, 14-day storage, distilled water, 37 degrees C) were produced and measured from three experimental protocols: no coating GIC (Group 1), GIC coating before water contamination (Group 2), GIC coating after water contamination (Group 3). The strength data were analyzed using Weibull statistics. Three-body wear resistance (Group 1 vs. Group 2) was measured after each 10,000 wear cycles up to a total of 200,000 cycles using the ACTA method. GIC microstructure and interfaces between GIC and coating materials were investigated under SEM and CLSM. The highest FS of 26.1 MPa and the most homogenous behavior (m = 7.7) has been observed in Group 2. The coated and uncoated GIC showed similar wear resistance until 90,000 cycles. After 200,000 wear cycles, the coated version showed significantly higher wear rate (ANOVA, P< 0.05). The coating protocol has been shown to determine the GIC fracture strength. Coating after water contamination and air drying is leading to surface crack formation thus significantly reducing the FS. The resin coating showed a proper sealing of GIC surface porosities and cracks. In terms of wear, the coating did not improve the wear resistance of the underlying cement as similar or higher wear rates have been measured for Group 1 versus Group 2.

  20. Prepolishing on a CNC platform with bound abrasive contour tools

    NASA Astrophysics Data System (ADS)

    Schoeffler, Adrienne E.; Gregg, Leslie L.; Schoen, John M.; Fess, Edward M.; Hakiel, Michael; Jacobs, Stephen D.

    2003-05-01

    Deterministic microgrinding (DMG) of optical glasses and ceramics is the commercial manufacturing process of choice to shape glass surfaces prior to final finishing. This process employs rigid bound matrix diamond tooling resulting in surface roughness values of 3-5μm peak to valley and 100-400nm rms, as well as mid-spatial frequency tool marks that require subsequent removal in secondary finishing steps. The ability to pre-polish optical surfaces within the grinding platform would reduce final finishing process times. Bound abrasive contour wheels containing cerium oxide, alumina or zirconia abrasives were constructed with an epoxy matrix. The effects of abrasive type, composition, and erosion promoters were examined for tool hardness (Shore D), and tested with commercial optical glasses in an Optipro CNC grinding platform. Metrology protocols were developed to examine tool wear and subsequent surface roughness. Work is directed to demonstrating effective material removal, improved surface roughness and cutter mark removal.

  1. Dental Wear: Attrition, Erosion, and Abrasion—A Palaeo-Odontological Approach

    PubMed Central

    Sperber, Geoffrey H.

    2017-01-01

    This paper reviews the surface ablation of early hominin teeth by attrition, abrasion, and erosive dental wear. The occurrence of these lesions is explored in a sample of South African fossil australopithecine dentitions revealing excessive wear. Interpretation of the nature of the dietary components causing such wear in the absence of carious erosion provides insight into the ecology of the Plio-pleistocene epoch (1–2 million years ago). Fossil teeth inform much of the living past by their retained evidence after death. Tooth wear is the ultimate forensic dental evidence of lives lived. PMID:29563425

  2. In Vitro Wear Resistance of Nano-Hybrid Composite Denture Teeth.

    PubMed

    Munshi, Nabeel; Rosenblum, Marc; Jiang, Shuying; Flinton, Robert

    2017-04-01

    To evaluate the wear resistance of nano-hybrid composite denture teeth as compared to two commonly used denture teeth: interpenetrating polymer network (IPN) and double crosslinking polymethylmethacrylate (PMMA) denture teeth. 18 styli and 18 disk specimens were prepared from the three denture tooth materials: nano-hybrid composite, IPN, and double crosslinking PMMA. The specimens were mounted in a two-body wear testing machine to simulate chewing in the complete denture. The amount of wear from the styli specimens were measured before and after using a digital micrometer, and the depth of the wear track from the disk specimens was measured using a noncontact 3D optical profilometer. The total wear from each denture tooth group was compared using one-way ANOVA with a 0.05 significance level. A Tukey post hoc test was used to determine differences between the three groups. The mean total wear in the nano-hybrid composite teeth group was 1.16 mm, SD = 0.5 mm, statistically significantly higher (p ≤ 0.0001) than the IPN (mean = 0.13 mm, SD = 0.05) and double crosslinking PMMA tooth groups (mean = 0.31 mm, SD = 0.19). There was no statistically significant difference between IPN denture teeth and double crosslinking PMMA denture teeth in the amount of wear. Nano-hybrid composite denture teeth exhibited statistically significantly more wear than the IPN and double crosslinking PMMA denture teeth. © 2015 by the American College of Prosthodontists.

  3. Design of Wear-Resistant Austenitic Steels for Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Lemke, J. N.; Casati, R.; Lecis, N.; Andrianopoli, C.; Varone, A.; Montanari, R.; Vedani, M.

    2018-03-01

    Type 316L stainless steel feedstock powder was modified by alloying with powders containing carbide/boride-forming elements to create improved wear-resistant austenitic alloys that can be readily processed by Selective Laser Melting. Fe-based alloys with high C, B, V, and Nb contents were thus produced, resulting in a microstructure that consisted of austenitic grains and a significant amount of hard carbides and borides. Heat treatments were performed to modify the carbide distribution and morphology. Optimal hard-phase spheroidization was achieved by annealing the proposed alloys at 1150 °C for 1 hour followed by water quenching. The total increase in hardness of samples containing 20 pct of C/B-rich alloy powder was of 82.7 pct while the wear resistance could be increased by a factor of 6.

  4. Comparison of mechanical and tribotechnical properties of UHMWPE reinforced with basalt fibers and particles

    NASA Astrophysics Data System (ADS)

    Panin, S. V.; Kornienko, L. A.; Alexenko, V. O.; Qitao, Huang; Ivanova, L. R.

    2016-11-01

    Mechanical and tribotechnical properties of UHMWPE composites reinforced with basalt fibers and particles under dry sliding friction and abrasion were investigated. It is shown that adding of the basalt particles provides higher wear resistance under the dry sliding friction while at abrasion filling by the basalt fibers is more efficient since the wear resistance of the reinforced UHMWPE composites is by 3.7 times higher in contrast with the neat polymer. Wear mechanisms of the polymeric UHMWPE composites under various types of wear are discussed.

  5. Corrosion Damage and Wear Mechanisms in Long-Term Retrieved CoCr Femoral Components for Total Knee Arthroplasty.

    PubMed

    Arnholt, Christina M; MacDonald, Daniel W; Malkani, Arthur L; Klein, Gregg R; Rimnac, Clare M; Kurtz, Steven M; Kocagoz, Sevi B; Gilbert, Jeremy L

    2016-12-01

    Metal debris and ion release has raised concerns in joint arthroplasty. The purpose of this study was to characterize the sources of metallic ions and particulate debris released from long-term (in vivo >15 years) total knee arthroplasty femoral components. A total of 52 CoCr femoral condyles were identified as having been implanted for more than 15 years. The femoral components were examined for incidence of 5 types of damage (metal-on-metal wear due to historical polyethylene insert failure, mechanically assisted crevice corrosion at taper interfaces, cement interface corrosion, third-body abrasive wear, and inflammatory cell-induced corrosion [ICIC]). Third-body abrasive wear was evaluated using the Hood method for polyethylene components and a similar method quantifying surface damage of the femoral condyle was used. The total area damaged by ICIC was quantified using digital photogrammetry. Surface damage associated with corrosion and/or CoCr debris release was identified in 51 (98%) CoCr femoral components. Five types of damage were identified: 98% of femoral components exhibited third-body abrasive wear (mostly observed as scratching, n = 51/52), 29% of femoral components exhibited ICIC damage (n = 15/52), 41% exhibited cement interface damage (n = 11/27), 17% exhibited metal-on-metal wear after wear-through of the polyethylene insert (n = 9/52), and 50% of the modular femoral components exhibited mechanically assisted crevice corrosion taper damage (n = 2/4). The total ICIC-damaged area was an average of 0.11 ± 0.12 mm 2 (range: 0.01-0.46 mm 2 ). Although implant damage in total knee arthroplasty is typically reported with regard to the polyethylene insert, the results of this study demonstrate that abrasive and corrosive damage occurs on the CoCr femoral condyle in vivo. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Mobile-bearing knees reduce rotational asymmetric wear.

    PubMed

    Ho, Fang-Yuan; Ma, Hon-Ming; Liau, Jiann-Jong; Yeh, Chuan-Ren; Huang, Chun-Hsiung

    2007-09-01

    Polyethylene wear of bearing components is the most common long-term complication in total knee arthroplasty. One would anticipate differing kinematics would generate different wear patterns (including wear type, degree, and symmetry) on the articulating surface of mobile-bearing and fixed-bearing inserts. Because mobile-bearing designs facilitate movement of the insert relative to the tray when the knee rotates, we hypothesized mobile-bearing designs would reduce the incidence of rotational asymmetric wear. We examined 51 worn tibial inserts, including 15 from mobile-bearing rotating-platform posterior-cruciate-sacrificing dished prostheses and 36 from fixed-bearing posterior-cruciate-retaining flat prostheses, which were retrieved at revision surgery with an average implantation time of 115 months. We divided wear types into low-grade wear (burnishing, abrasion, and cold flow) and high-grade wear (scratching, pitting, metal embedding, and delamination) to assess wear degree of polyethylene. To assess symmetry of wear, the insert surface was divided into medial and lateral sides and each side was further divided into three equal zones along the anteroposterior direction. Low-grade wear was more common in mobile-bearing knees, whereas high-grade wear was more common in fixed-bearing knees. We identified no internal/external rotational asymmetric wear or anteroposterior asymmetric wear in mobile-bearing knees.

  7. Gear Tooth Wear Detection Algorithm

    NASA Technical Reports Server (NTRS)

    Delgado, Irebert R.

    2015-01-01

    Vibration-based condition indicators continue to be developed for Health Usage Monitoring of rotorcraft gearboxes. Testing performed at NASA Glenn Research Center have shown correlations between specific condition indicators and specific types of gear wear. To speed up the detection and analysis of gear teeth, an image detection program based on the Viola-Jones algorithm was trained to automatically detect spiral bevel gear wear pitting. The detector was tested using a training set of gear wear pictures and a blind set of gear wear pictures. The detector accuracy for the training set was 75 percent while the accuracy for the blind set was 15 percent. Further improvements on the accuracy of the detector are required but preliminary results have shown its ability to automatically detect gear tooth wear. The trained detector would be used to quickly evaluate a set of gear or pinion pictures for pits, spalls, or abrasive wear. The results could then be used to correlate with vibration or oil debris data. In general, the program could be retrained to detect features of interest from pictures of a component taken over a period of time.

  8. Development of Abrasion-Resistant Coating for Solar Reflective Films. Cooperative Research and Development Final Report, CRADA Number CRD-07-247

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gray, Matthew

    The purpose of this CRADA is to develop an abrasion-resistant coating, suitable for use on polymeric-based reflective films (e.g., the ReflecTech reflective film), that allows for improved scratch resistance and enables the use of aggressive cleaning techniques (e.g., direct contact methods like brushing) without damaging the specular reflectance properties of the reflective film.

  9. Influence of Surface Features for Increased Heat Dissipation on Tool Wear

    PubMed Central

    Beno, Tomas; Hoier, Philipp; Wretland, Anders

    2018-01-01

    The critical problems faced during the machining process of heat resistant superalloys, (HRSA), is the concentration of heat in the cutting zone and the difficulty in dissipating it. The concentrated heat in the cutting zone has a negative influence on the tool life and surface quality of the machined surface, which in turn, contributes to higher manufacturing costs. This paper investigates improved heat dissipation from the cutting zone on the tool wear through surface features on the cutting tools. Firstly, the objective was to increase the available surface area in high temperature regions of the cutting tool. Secondly, multiple surface features were fabricated for the purpose of acting as channels in the rake face to create better access for the coolant to the proximity of the cutting edge. The purpose was thereby to improve the cooling of the cutting edge itself, which exhibits the highest temperature during machining. These modified inserts were experimentally investigated in face turning of Alloy 718 with high-pressure coolant. Overall results exhibited that surface featured inserts decreased flank wear, abrasion of the flank face, cutting edge deterioration and crater wear probably due to better heat dissipation from the cutting zone. PMID:29693579

  10. [An in vitro investigation of wear resistance and hardness of three kinds of new composite resins].

    PubMed

    Wang, Li-kai; Shi, Lian-shui; Zhu, Hong-shui

    2008-02-01

    To evaluate wear resistance and hardness of three kinds of new composite resins. Three kinds of new composite resins, Solidex, Spectrum, Filtek Z350, were tested. Enamel as control group. A refited MG-200 wear machine was used in this study. Scanning electron microscope (SEM) was used to observe the friction surface of each tested material. Hardness of each tested material was determined by Vickers indentation technique. The data of wear and hardness were analyzed by Mann-Whitney test and 1-way ANOVA. The relationship between the hardness of the composites and the amount of wear of them was determined by a regression analysis method. Filtek Z350 showed the lowest volumetric wear and highest Vickers hardness in the composites (P < 0.05). No significant differences in wear and hardness were observed between Solidex and Spectrum (P > 0.05). Significant relationships were observed between the hardness of the composites and the amount of wear of them (r = 0.968 6) (P < 0.05). Different wear characters of the friction surface of the tested materials were observed by SEM. Nanofilled composite was superior to the hybrid composite in wear resistance and hardness.

  11. Enhancing wear resistance of working bodies of grinder through lining crushed material

    NASA Astrophysics Data System (ADS)

    Romanovich, A. A.; Annenko, D. M.; Romanovich, M. A.; Apukhtina, I. V.

    2018-03-01

    The article presents the analysis of directions of increasing wear resistance of working surfaces of rolls. A technical solution developed at the level of the invention is proposed, which is simple to implement in production conditions and which makes it possible to protect the roll surface from heavy wear due to surfacing of wear-resistant mesh material, cells of which are filling with grinding material in the process of work. Retaining them enables one to protect the roll surface from wear. The paper dwells on conditions of pressing materials in cells of eccentric rolls on the working surface with a grid of rectangular shape. The paper presents an equation for calculation of the cell dimension that provides the lining of the working surface by a mill material with respect to its properties. The article presents results of comparative studies on the grinding process of a press roller grinder (PRG) between rolls with and without a fusion-bonded mesh. It is clarified that the lining of rolls working surface slightly reduces the quality of the grinding, since the material thickness in the cell is small and has a finely divided and compacted structure with high strength.

  12. Wear rate quantifying in real-time using the charged particle surface activation

    NASA Astrophysics Data System (ADS)

    Alexandreanu, B.; Popa-Simil, L.; Voiculescu, D.; Racolta, P. M.

    1997-02-01

    Surface activation, commonly known as Thin Layer Activation (TLA), is currently employed in over 30 accelerator laboratories around the world for wear and/or corrosion monitoring in industrial plants [1-6]. TLA was primarily designed and developed to meet requirements of potential industrial partners, in order to transfer this technique from research to industry. The method consists of accelerated ion bombardment of a surface of interest, e.g., a machine part subjected to wear. Loss of material owing to wear, erosive corrosion or abrasion is characterized by monitoring the resultant changes in radioactivity. In principle, depending upon the case at hand, one may choose to measure either the remnant activity of the component of interest or to monitor the activity of the debris. For applications of the second type, especially when a lubricating agent is involved, dedicated installations have been constructed and adapted to an engine or a tribological testing stand in order to assure oil circulation around an externally placed detection gauge. This way, the wear particles suspended in the lubricant can be detected and the material loss rates quantified in real time. Moreover, in specific cases, such as the one presented in this paper, remnant activity measurements prove to be useful tools for complementary results. This paper provides a detailed presentation of such a case: in situ resistance-to-wear testing of two types of piston rings.

  13. Improved wear resistance by phase transformation of surface nanocrystalline 1090 steel prepared by sandblasting technique

    NASA Astrophysics Data System (ADS)

    Peng, Rong; Fu, Licai; Zhou, Lingping

    2016-12-01

    A surface nanocrystalline 1090 steel has been fabricated by using sandblasting technique. The surface average grain size was about 78 nm. The high strain rate and strain in sandblasting were main reasons for surface nanocrystallization. The wear resistance of 1090 steel was considerably enhanced as grain size decreased. The microstructure and hardness of contact zones before and after wear tests have been examined by XRD, SEM and TEM. Except the higher hardness, the results demonstrated that parts of ferrite transferred to cementite and martensite. It was additional beneficial for improving the wear resistance of 1090 steel as the grain size decreased.

  14. An in vitro investigation of wear resistance and hardness of composite resins.

    PubMed

    Cao, Liqun; Zhao, Xinyi; Gong, Xu; Zhao, Shouliang

    2013-01-01

    The aim of the present study was to investigate the wear resistance and hardness of five kinds of composite resins. Sixty-five specimens were fabricated with one nano-hybrid (Charisma Diamond), two micro-hybrid (3MZ250, Clearfil AP-X) and two packable (3MP60, Surefil) composite resins, according to a randomized complete block design (n=13, 8 for wear test; 5 for hardness test). The composites were filled in a rectangular mold, and light polymerization. After storage in 37°C deionized water for 24h, all specimens were tested with a custom-made toothbrush machine with a stainless-steel ball as antagonist (3N loads, 1Hz, 6×10(5) cycles) immersed in calcium fluoride slurry. Wear volume, hardness and surface structure of each tested material was examined by a three-dimensional non-contact optical profilometer, Vickers indentation technique and scanning electron microscope. The volume loss ranked from least to most as follows: Charisma Diamond, P60, Z250, Clearfil AP-X and Surefil. Regarding hardness, the rank from highest to lowest as follows: Clearfil AP-X, P60, Surefil, Z250, Charisma Diamond. The interactions between wear resistance and microhardness were not significant. The custom-made machine is considered suitable to simulate sliding of an antagonist cusp on an opposing occlusal composite restoration. Nanofilled composite may have superior wear compared to other composite resins.

  15. Wear Behaviour of Al-6061/SiC Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Mishra, Ashok Kumar; Srivastava, Rajesh Kumar

    2017-04-01

    Aluminium Al-6061 base composites, reinforced with SiC particles having mesh size of 150 and 600, which is fabricated by stir casting method and their wear resistance and coefficient of friction has been investigated in the present study as a function of applied load and weight fraction of SiC varying from 5, 10, 15, 20, 25, 30, 35 and 40 %. The dry sliding wear properties of composites were investigated by using Pin-on-disk testing machine at sliding velocity of 2 m/s and sliding distance of 2000 m over a various loads of 10, 20 and 30 N. The result shows that the reinforcement of the metal matrix with SiC particulates up to weight percentage of 35 % reduces the wear rate. The result also show that the wear of the test specimens increases with the increasing load and sliding distance. The coefficient of friction slightly decreases with increasing weight percentage of reinforcements. The wear surfaces are examined by optical microscopy which shows that the large grooved regions and cavities with ceramic particles are found on the worn surface of the composite alloy. This indicates an abrasive wear mechanism, which is essentially a result of hard ceramic particles exposed on the worn surfaces. Further, it was found from the experimentation that the wear rate decreases linearly with increasing weight fraction of SiC and average coefficient of friction decreases linearly with increasing applied load, weight fraction of SiC and mesh size of SiC. The best result has been obtained at 35 % weight fraction and 600 mesh size of SiC.

  16. Wear of dental tissues and materials.

    PubMed

    Craig, R G; Powers, J M

    1976-06-01

    Wear may result from physiological or pathological conditions and may be desirable, as in the reduction of an overcontoured restoration, or undesirable as in the production of cervical abrasion cavities. A variety of methods, including clinical testing, the use of wear machines and the measurement of related properties such as hardness or coefficient of friction have been used to investigate wear of tooth tissue and of dental materials. Because these methods may not reveal the nature of the wear process recent work has been directed to the study of surface failure resulting from a single sliding contact. Many clinical studies have been conducted but they are time consuming and difficult to quantify, nor do they allow of evaluation of different parameters contributing to the wear. Laboratory simulation of wear has been shown to be valuable in comparing materials of the same group but between-group comparisons may give anomalous results. The most rewarding studies have been those using a single or small number of passes of a suitable abrading point over the material since these permit determination of the actual process by which wear is produced.

  17. Deposition of Coatings for Raising the Wear Resistance of Friction Surfaces of Spherical Sliding Bearings

    NASA Astrophysics Data System (ADS)

    Gorlenko, A. O.; Davydov, S. V.

    2018-01-01

    The process of finishing plasma hardening with deposition of a multilayer amorphous coating of the Si - O - C - N system is considered as applied to hardening of the friction surfaces of spherical sliding bearings. The microrelief, the submicrorelief, and the tribological characteristics of the deposited wear-resistant antifriction amorphous coating, which are responsible for the elevated wear resistance of spherical sliding bearings, are investigated.

  18. Pre-polishing on a CNC platform with bound abrasive contour tools

    NASA Astrophysics Data System (ADS)

    Schoeffer, Adrienne E.

    2003-05-01

    Deterministic micorgrinding (DMG) of optical glasses and ceramics is the commercial manufacturing process of choice to shape glass surfaces prior to final finishing. This process employs rigid bound matrix diamond tooling resulting in surface roughness values of 3-51.tm peak to valley and 100-400nm rms, as well as mid-spatial frequency tool marks that require subsequent removal in secondary finishing steps. The ability to pre-polish optical surfaces within the grinding platform would reduce final finishing process times. Bound abrasive contour wheels containing cerium oxide, alumina or zirconia abrasives were constructed with an epoxy matrix. The effects of abrasive type, composition, and erosion promoters were examined for tool hardness (Shore D), and tested with commercial optical glasses in an OptiproTM CNC grinding platform. Metrology protocols were developed to examine tool wear and subsequent surface roughness. Work is directed to demonstrating effective material removal, improved surface roughness and cutter mark removal.

  19. NASA Glenn/AADC-Rolls Royce Collaborated to Measure Erosion Resistance on Coated Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Sutter, James K.; Mondry, Richard; Ma, Kong; Horan, Dick; Naik, Subhash; Cupp, Randall

    2003-01-01

    Polymer matrix composites (PMCs) are increasingly used in aerospace and automotive applications because of their light weight and high strength-to-weight ratio relative to metals. However, a major drawback of PMCs is poor abrasion resistance, which restricts their use, especially at high temperatures. Simply applying a hard coating on PMCs to improve abrasion and erosion resistance is not effective since coating durability is short lived (ref. 1). Generally, PMCs have higher coefficients of thermal expansion than metallic or ceramic coatings have, and coating adhesion suffers because of poor interfacial adhesion strength. One technique commonly used to improve coating adhesion or durability is the use of bond coats that are interleaved between a coating and a substrate with vastly different coefficients of thermal expansion. An example of this remedy is the use of bondcoats for ceramic thermal barrier coatings on metallic turbine components (ref. 2). Prior collaborative research between the NASA Glenn Research Center and the Allison Advanced Development Company (AADC) demonstrated that bond coats sandwiched between PMCs and high-quality plasma-sprayed, erosion-resistant coatings substantially improved the erosion resistance of PMCs (ref. 3). One unresolved problem in this earlier collaboration was that there was no easy, accurate way to measure the coating erosion wear scar. Coating wear was determined by both profilometry and optical microscopy. Both techniques are time consuming. Wear measurement by optical microscopy requires sample destruction and does not provide a comprehensive measure of the entire wear volume. An even more subtle, yet critical, problem is that these erosion coatings contain two or more materials with different densities. Therefore, simply measuring specimen mass loss before and after erosion will not provide an accurate gauge for coating and/or substrate volume loss. By using a noncontact technique called scanning optical interferometry

  20. Microstructure and wear behaviors of laser clad NiCr/Cr3C2-WS2 high temperature self-lubricating wear-resistant composite coating

    NASA Astrophysics Data System (ADS)

    Yang, Mao-Sheng; Liu, Xiu-Bo; Fan, Ji-Wei; He, Xiang-Ming; Shi, Shi-Hong; Fu, Ge-Yan; Wang, Ming-Di; Chen, Shu-Fa

    2012-02-01

    The high temperature self-lubricating wear-resistant NiCr/Cr3C2-30%WS2 coating and wear-resistant NiCr/Cr3C2 coating were fabricated on 0Cr18Ni9 austenitic stainless steel by laser cladding. Phase constitutions and microstructures were investigated, and the tribological properties were evaluated using a ball-on-disc wear tester under dry sliding condition at room-temperature (17 °C), 300 °C and 600 °C, respectively. Results indicated that the laser clad NiCr/Cr3C2 coating consisted of Cr7C3 primary phase and γ-(Fe,Ni)/Cr7C3 eutectic colony, while the coating added with WS2 was mainly composed of Cr7C3 and (Cr,W)C carbides, with the lubricating WS2 and CrS sulfides as the minor phases. The wear tests showed that the friction coefficients of two coatings both decrease with the increasing temperature, while the both wear rates increase. The friction coefficient of laser clad NiCr/Cr3C2-30%WS2 is lower than the coating without WS2 whatever at room-temperature, 300 °C, 600 °C, but its wear rate is only lower at 300 °C. It is considered that the laser clad NiCr/Cr3C2-30%WS2 composite coating has good combination of anti-wear and friction-reducing capabilities at room-temperature up to 300 °C.

  1. Wear simulation of resin composites and the relationship to clinical wear.

    PubMed

    Barkmeier, Wayne W; Latta, Mark A; Erickson, Robert L; Wilwerding, Terry M

    2008-01-01

    This study used a new generalized wear model to examine the relationship between wear simulation and the clinical wear of two resin composites. Ten specimens each of P50 and Z100, were subjected to 100,000, 400,000 and 800,000 cycles in a spring-loaded piston-type wear simulator. Wear was generated using flat, cylindrically-shaped stainless steel antagonists on the resin composites, which were placed in custom stainless steel fixtures. A slurry of polymethyl methacrylate beads was used as the abrasive media. Wear was determined using profilometry, and the parameters examined included volume loss (mm3), maximum depth (microm), mean maximum depth (microm) and mean depth (microm). Statistical analysis of the laboratory wear data using ANOVA and Tukey's post hoc test showed a significant difference (p<0.05) for wear between the two materials and the number of cycles. Mean maximum wear (microm) values (100K--P50--11.5 +/- 1.8; Z100--4.9 +/- 1.0; 400K--P50--17.2 +/- 2.7; Z100--6.0 +/- 1.7; 800K--P50--20.5 +/- 4.6; Z100--9.6 +/- 2.5) were used for comparisons with clinical data. Previous clinical studies of P50 and Z100 were used to examine the relationship between laboratory and clinical wear. Linear regression analysis was used to predict laboratory and clinical wear rates. The laboratory wear rate for P50 was 1.3 microm/100K cycles and the rate for Z100 was 0.7 microm/100K cycles. The clinical wear rates for P50 and Z100 were 8.3 microm/year and 4.0 microm/year, respectively. The ratio of wear rates of P50 to Z100 for wear simulation was 1.9 and the ratio of P50 to Z100 for clinical rates was 2.1. These ratios showed good agreement between the relative wear rates of laboratory and clinical wear. For the two composite materials examined, this new simulation model appears to be effective for evaluating the relative wear of resin composites.

  2. EVALUATION AND RECOMMENDATION OF SALTSTONE MIXER AUGER/PADDLES MATERIALS OF CONSTRUCTION FOR IMPROVED WEAR RESISTANCE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mickalonis, J.; Torres, R.

    2012-08-15

    Wear and corrosion testing were conducted to evaluate alternate materials of construction for the Saltstone mixer auger and paddles. These components have been degraded by wear from the slurry processed in the mixer. Material test options included PVD coatings (TiN, TiCN, and ZrN), weld overlays (Stellite 12 and Ultimet) and higher hardness steels and carbides (D2 and tungsten carbide). The corrosion testing demonstrated that the slurry is not detrimental to the current materials of construction or the new candidates. The ASTM G75 Miller wear test showed that the high hardness materials and the Stellite 12 weld overlay provide superior wearmore » relative to the Astralloy and CF8M stainless steel, which are the current materials of construction, as well as the PVD coatings and Ultimet. The following recommendations are made for selecting new material options and improving the overall wear resistance of the Saltstone mixer components: A Stellite 12 weld overlay or higher hardness steel (with toughness equivalent to Astralloy) be used to improve the wear resistance of the Saltstone mixer paddles; other manufacturing specifications for the mixer need to be considered in this selection. The current use of the Stellite 12 weld overlay be evaluated so that coverage of the 316 auger can be optimized for improved wear resistance of the auger. The wear surfaces of the Saltstone mixer auger and paddles be evaluated so that laboratory data can be better correlated to actual service. The 2-inch Saltstone mixer prototype be used to verify material performance.« less

  3. Plasma spray processing of TiC-based coatings for sliding wear resistance

    NASA Astrophysics Data System (ADS)

    Mohanty, Mahesh

    Titanium carbide-reinforced metallic coatings, produced by plasma spraying, can be used for sliding wear resistant applications. The sliding wear properties of such coatings are governed to a large extent by the strength, structure and stability of the bond interface between the carbide and the metallic phases. In the present investigation, the microstructure and sliding wear properties of plasma sprayed metal-bonded TiC coatings containing up to 90 v/o carbide have been studied. It was shown that alloying of the metallic phase improved carbide retention in TiC cermets due to better interface bonding, and increased wear resistance and lowered sliding coefficient of friction. TiC-based coatings were produced from both physically blended and synthesized feed powders. It was observed that the precursor TiC-based powder morphology and structure greatly affected the plasma sprayed coating microstructures and the resultant physical and mechanical characteristics. Physical blending of powders induced segregation during spraying, leading to somewhat lower deposit efficiencies and coating uniformity, while synthesized and alloyed titanium carbide/metal composite powders reduced problems of segregation and reactions associated with plasma spraying of physically blended powders where the TiC was in direct contact with the plasma jet. To understand oxidation effects of the environment, Ti and TiC-based coatings were produced under low pressure (VPS), air plasma (APS) and shrouded plasma sprayed conditions. APS Ti and TiC-based powders with reactive matrices suffered severe oxidation decomposition during flight, leading to poor deposition efficiencies and oxidized microstructures. High particle temperatures and cold air plasma spraying. Coating oxidation due to reactions of the particles with the surrounding air during spraying reduced coating hardness and wear resistance. TiC-with Ti or Ti-alloy matrix coatings with the highest hardness, density and wear resistance was

  4. Nanostructured wear resistant coating for reversible cultivator shovels: An experimental investigation

    NASA Astrophysics Data System (ADS)

    Dave, V.; Rao, G. P.; Tiwari, G. S.; Sanger, A.; Kumar, A.; Chandra, R.

    2016-04-01

    Cultivator, one of the agriculture farm tool, extensively suffers from the wear problem. In this paper, we report nanostructured chromium nitrite (CrN) coating for the cultivator shovels to mitigate wear problem. The (CrN) coating was developed using DC magnetron sputtering technique at 200 °C. The structural, morphological, hydrophobic and wear properties were investigated using X-ray diffractometer, scanning electron microscope, contact angle goniometer and custom designed soil bin assembly. The XRD reveals that the deposited coating was polycrystalline in nature with cubic structure. Also, The deposited coating was found to be anti wear resistant as well as hydrophobic in nature. The gravimetric wear for the coating developed at 200 °C coated was found out to be 8.15 gm and for non coated it was 14.48 gm tested for 100 hrs. The roughness of the coating plays an important role in determining the hydrophobicity of the coated film. Roughness and contact angle measured for 200 °C coated shovel was found out to be 11.17 nm and 105 ° respectively.

  5. Effect of Al2O3sf addition on the friction and wear properties of (SiCp+Al2O3sf)/Al2024 composites fabricated by pressure infiltration

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Zhang, Gong-zhen; Cui, Wei; Ren, Shu-bin; Wang, Qian-jin; Qu, Xuan-hui

    2018-03-01

    Aluminum (Al) 2024 matrix composites reinforced with alumina short fibers (Al2O3sf) and silicon carbide particles (SiCp) as wear-resistant materials were prepared by pressure infiltration in this study. Further, the effect of Al2O3sf on the friction and wear properties of the as-synthesized composites was systematically investigated, and the relationship between volume fraction and wear mechanism was discussed. The results showed that the addition of Al2O3sf, characterized by the ratio of Al2O3sf to SiCp, significantly affected the properties of the composites and resulted in changes in wear mechanisms. When the volume ratio of Al2O3sf to SiCp was increased from 0 to 1, the rate of wear mass loss ( K m) and coefficients of friction (COFs) of the composites decreased, and the wear mechanisms were abrasive wear and furrow wear. When the volume ratio was increased from 1 to 3, the COF decreased continuously; however, the K m increased rapidly and the wear mechanism became adhesive wear.

  6. A review of the use of wear-resistant coatings in the cutting-tool industry

    NASA Technical Reports Server (NTRS)

    Salik, J.

    1983-01-01

    The main mechanisms involved in the wear of cutting tools are reviewed. Evaluation of the different coating properties required for the reduction of the different kinds of wear was also reviewed. The types of coatings and their ranges of applicability are presented and discussed in view of their properties. Various coating processes as well as their advantages and shortcomings are described. Potential future developments in the field of wear-resistant coatings are discussed.

  7. The High performance of nanocrystalline CVD diamond coated hip joints in wear simulator test.

    PubMed

    Maru, M M; Amaral, M; Rodrigues, S P; Santos, R; Gouvea, C P; Archanjo, B S; Trommer, R M; Oliveira, F J; Silva, R F; Achete, C A

    2015-09-01

    The superior biotribological performance of nanocrystalline diamond (NCD) coatings grown by a chemical vapor deposition (CVD) method was already shown to demonstrate high wear resistance in ball on plate experiments under physiological liquid lubrication. However, tests with a close-to-real approach were missing and this constitutes the aim of the present work. Hip joint wear simulator tests were performed with cups and heads made of silicon nitride coated with NCD of ~10 μm in thickness. Five million testing cycles (Mc) were run, which represent nearly five years of hip joint implant activity in a patient. For the wear analysis, gravimetry, profilometry, scanning electron microscopy and Raman spectroscopy techniques were used. After 0.5 Mc of wear test, truncation of the protruded regions of the NCD film happened as a result of a fine-scale abrasive wear mechanism, evolving to extensive plateau regions and highly polished surface condition (Ra<10nm). Such surface modification took place without any catastrophic features as cracking, grain pullouts or delamination of the coatings. A steady state volumetric wear rate of 0.02 mm(3)/Mc, equivalent to a linear wear of 0.27 μm/Mc favorably compares with the best performance reported in the literature for the fourth generation alumina ceramic (0.05 mm(3)/Mc). Also, squeaking, quite common phenomenon in hard-on-hard systems, was absent in the present all-NCD system. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. The in vitro wear behavior of experimental resin-based composites derived from a commercial formulation.

    PubMed

    Finlay, Nessa; Hahnel, Sebastian; Dowling, Adam H; Fleming, Garry J P

    2013-04-01

    To investigate the short- and long-term in vitro wear resistance of experimental resin-based composites (RBCs) derived from a commercial formulation. Six experimental RBCs were manufactured by manipulating the monomeric resin composition and the filler characteristics of Grandio (Voco GmbH, Cuxhaven, Germany). The Oregon Health Sciences University (OHSU) oral wear simulator was used in the presence of a food-like slurry to simulate three-body abrasion and attrition wear for 50,000, 150,000 and 300,000 cycles. A three-dimensional image of each wear facet was created and the total volumetric wear (mm(3)) and maximum wear depth (μm) were quantified for the RBC and antagonist. Statistical analyses of the total volumetric wear and maximum wear depth data (two- and one-way analyses of variance (ANOVA), with Tukey's post hoc tests where required) and regression analyses, were conducted at p=0.05. Two-way ANOVAs identified a significant effect of RBC material×wear cycles, RBC material and wear cycles (all p<0.0001). Regression analyses showed significant increases in the total volumetric wear (p≤0.001) and maximum wear depth data (p≤0.004) for all RBCs with increasing wear cycles. Differences between all RBC materials were evident after ≥150,000 wear cycles and antagonist wear provided valuable information to support the experimental findings. Wear simulating machines can provide an indication of the clinical performance but clinical performance is multi-factorial and wear is only a single facet. Employing experimental RBCs provided by a dental manufacturer rather than using self-manufactured RBCs or dental products provides increased experimental control by limiting the variables involved. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  9. An in vitro investigation of wear resistance and hardness of composite resins

    PubMed Central

    Cao, Liqun; Zhao, Xinyi; Gong, Xu; Zhao, Shouliang

    2013-01-01

    Purpose: The aim of the present study was to investigate the wear resistance and hardness of five kinds of composite resins. Materials and Methods: Sixty-five specimens were fabricated with one nano-hybrid (Charisma Diamond), two micro-hybrid (3MZ250, Clearfil AP-X) and two packable (3MP60, Surefil) composite resins, according to a randomized complete block design (n=13, 8 for wear test; 5 for hardness test). The composites were filled in a rectangular mold, and light polymerization. After storage in 37°C deionized water for 24h, all specimens were tested with a custom-made toothbrush machine with a stainless-steel ball as antagonist (3N loads, 1Hz, 6×105 cycles) immersed in calcium fluoride slurry. Wear volume, hardness and surface structure of each tested material was examined by a three-dimensional non-contact optical profilometer, Vickers indentation technique and scanning electron microscope. Results: The volume loss ranked from least to most as follows: Charisma Diamond, P60, Z250, Clearfil AP-X and Surefil. Regarding hardness, the rank from highest to lowest as follows: Clearfil AP-X, P60, Surefil, Z250, Charisma Diamond. The interactions between wear resistance and microhardness were not significant. Conclusions: The custom-made machine is considered suitable to simulate sliding of an antagonist cusp on an opposing occlusal composite restoration. Nanofilled composite may have superior wear compared to other composite resins. PMID:23844265

  10. Comparison between different interdental stripping methods and evaluation of abrasive strips: SEM analysis.

    PubMed

    Grippaudo, Cristina; Cancellieri, Daniela; Grecolini, Maria E; Deli, Roberto

    2010-01-01

    The aim of this study was to evaluate the morphological effects and the surface irregularities produced by different methods of mechanical stripping (abrasive strips and burs) and chemical stripping (37% orthophosphoric acid) and the surface changes following the finishing procedures (polishing strips) or the subsequent application of sealants, in order to establish the right stripping method that can guarantee the smoothest surface. We have also analysed the level of wear on the different abrasive strips employed, according to their structure. 160 proximal surfaces of 80 sound molar teeth extracted for orthodontic and periodontal reasons, were divided into: 1 control group with non-treated enamel proximal surfaces and 5 different groups according to the stripping method used, were observed with scanning electron microscopy (SEM). Each one of the 5 treated groups was also divided into 3 different subgroups according to the finishing procedures or the subsequent application of sealants. The finishing stage following the manual reduction proves to be fundamental in reducing the number and depth of grooves created by the stripping. After the air rotor stripping method, the use of sealants is advised in order to obtain a smoother surface. The analysis of the combinations of mechanical and chemical stripping showed unsatisfactory results. Concerning the wear of the strips, we have highlighted a different abrasion degree for the different types of strips analysed with SEM. The enamel damages are limited only if the finishing procedure is applied, independently of the type of abrasive strip employed. It would be advisable, though clinically seldom possible, the use of sealants after the air rotor stripping technique. Copyright © 2010 Società Italiana di Ortodonzia SIDO. Published by Elsevier Srl. All rights reserved.

  11. Effect of microstructure of superalloy guide plate on its surface wear resistance

    NASA Astrophysics Data System (ADS)

    Zhou, Jianbo; Zhang, Xizhen

    2018-03-01

    The microstructure had been observed for guide plate, the guide plate be made of casting for groove controlling of hot rolled seamless tube, be produced for the production of 1600 seamless steel pipe,which cause obvious surface deformation and can not be normally produced. The alloy elements in matrix and precipitate phase of the guide plate were analyzed with the help of EDS. The results show that the wear resistance of the guide plate is directly affected by the fact that the guide plate is unable to form typical carbides, it shows that the formation of typical carbide strengthening plays an important role in improving the surface wear resistance of the guide plate.

  12. Provision of wear resistance and fatigue strength of surfaces during electroerosive processing

    NASA Astrophysics Data System (ADS)

    Fedonin, O. N.; Syanov, S. Yu; Papikyan, A. M.

    2018-03-01

    This article is a generalization of the results of theoretical studies of the effect of erosion control regimes on the operational properties of mold-forming parts of molds. The main problem is the provision of wear resistance and fatigue strength in the electroerosion processing of these types of products. The analysis showed that the fatigue strength is affected by the processing regimes and the coefficient after the erosion treatment. The index of wear resistance is determined both by the treatment modes and by the physical-mechanical properties of the billet materials. To ensure the operational performance of products, it is necessary to establish the physical picture of the processing of complex profile parts by finding the optimum eroding regime.

  13. Development of wear resistant ceramic coatings for diesel engine components. Final report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Haselkorn, M.H.

    1992-04-01

    Improved fuel economy and a reduction of emissions can be achieved by insulation of the combustion chamber components to reduce heat rejection. However, insulating the combustion chamber components will also increase the operating temperature of the piston ring/cylinder liner interface from approximately 150{degree}C to over 300{degree}C. Existing ring/liner materials can not withstand these higher operating temperatures and for this reason, new materials need to be developed for this critical tribological interface. The overall goal of this program is the development of piston ring/cylinder liner material pairs which would be able to provide the required friction and wear properties at thesemore » more severe operating conditions. More specifically, this program first selected, and then evaluated, potential d/wear resistant coatings which could be applied to either piston rings an or cylinder liners and provide, at 350{degree}C under lubricated conditions, coefficients of friction below 0.1 and wear rates of less than 25 {times} lO{sup {minus}6} mm/hour. The processes selected for applying the candidate wear resistant coatings to piston rings and/or cylinder liners were plasma spraying, chemical vapor, physical vapor and low temperature arc vapor deposition techniques as well as enameling techniques.« less

  14. Effect of NaF, SnF(2), and TiF(4) Toothpastes on Bovine Enamel and Dentin Erosion-Abrasion In Vitro.

    PubMed

    Comar, Lívia Picchi; Gomes, Marina Franciscon; Ito, Naiana; Salomão, Priscila Aranda; Grizzo, Larissa Tercília; Magalhães, Ana Carolina

    2012-01-01

    The aim of this study was to compare the effect of toothpastes containing TiF(4), NaF, and SnF(2) on tooth erosion-abrasion. Bovine enamel and dentin specimens were distributed into 10 groups (n = 12): experimental placebo toothpaste (no F); NaF (1450 ppm F); TiF(4) (1450 ppm F); SnF(2) (1450 ppm F); SnF(2) (1100 ppm F) + NaF (350 ppm F); TiF(4) (1100 ppm F) + NaF (350 ppm F); commercial toothpaste Pro-Health (SnF(2)-1100 ppm F + NaF-350 ppm F, Oral B); commercial toothpaste Crest (NaF-1.500 ppm F, Procter & Gamble); abrasion without toothpaste and only erosion. The erosion was performed 4 × 90 s/day (Sprite Zero). The toothpastes' slurries were applied and the specimens abraded using an electric toothbrush 2 × 15 s/day. Between the erosive and abrasive challenges, the specimens remained in artificial saliva. After 7 days, the tooth wear was evaluated using contact profilometry (μm). The experimental toothpastes with NaF, TiF(4), SnF(2), and Pro-Health showed a significant reduction in enamel wear (between 42% and 54%). Pro-Health also significantly reduced the dentin wear. The toothpastes with SnF(2)/NaF and TiF(4)/NaF showed the best results in the reduction of enamel wear (62-70%) as well as TiF(4), SnF(2), SnF(2)/NaF, and TiF(4)/NaF for dentin wear (64-79%) (P < 0.05). Therefore, the experimental toothpastes containing both conventional and metal fluoride seem to be promising in reducing tooth wear.

  15. Effect of different concentrations of fluoride in dentifrices on dentin erosion subjected or not to abrasion in situ/ex vivo.

    PubMed

    Magalhães, A C; Rios, D; Moino, A L; Wiegand, A; Attin, T; Buzalaf, M A R

    2008-01-01

    This in situ/ex vivo study assessed the effect of different concentrations of fluoride in dentifrices on dentin subjected to erosion or to erosion plus abrasion. Ten volunteers took part in this crossover and double-blind study performed in 3 phases (7 days). They wore acrylic palatal appliances containing 4 bovine dentin blocks divided in two rows: erosion and erosion plus abrasion. The blocks were subjected to erosion by immersion ex vivo in a cola drink (60 s, pH 2.6) 4 times daily. During this step, the volunteers brushed their teeth with one of three dentifrices D (5,000 ppm F, NaF, silica); C (1,100 ppm F, NaF, silica) and placebo (22 ppm F, silica). Then, the respective dentifrice slurry (1:3) was dripped on dentin surfaces. While no further treatment was performed in one row, the other row was brushed using an electric toothbrush for 30 s ex vivo. The appliances were replaced in the mouth and the volunteers rinsed with water. Dentin loss was determined by profilometry and analyzed by 2-way ANOVA/Bonferroni test (a = 0.05). Dentin loss after erosive-abrasive wear was significantly greater than after erosion alone. Wear was significantly higher for the placebo than for the D and C dentifrices, which were not significantly different from each other. It can be concluded that the presence of fluoride concentrations around 1,100 ppm in dentifrices is important to reduce dentin wear by erosion and erosion + abrasion, but the protective effect does not increase with fluoride concentration. (c) 2008 S. Karger AG, Basel

  16. Surface Design and Engineering Toward Wear-Resistant, Self-Lubricant Diamond Films and Coatings. Chapter 10

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1999-01-01

    This chapter describes three studies on the surface design, surface engineering, and tribology of chemical-vapor-deposited (CVD) diamond films and coatings toward wear-resistant, self-lubricating diamond films and coatings. Friction mechanisms and solid lubrication mechanisms of CVD diamond are stated. Effects of an amorphous hydrogenated carbon on CVD diamond, an amorphous, nondiamond carbon surface layer formed on CVD diamond by carbon and nitrogen ion implantation, and a materials combination of cubic boron nitride and CVD diamond on the adhesion, friction, and wear behaviors of CVD diamond in ultrahigh vacuum are described. How surface modification and the selected materials couple improved the tribological functionality of coatings, giving low coefficient of friction and good wear resistance, is explained.

  17. Dry Sliding Wear Behavior and Subsurface Microstructure Evolution of Mg97Zn1Y2 Alloy in a Wide Sliding Speed Range

    NASA Astrophysics Data System (ADS)

    An, J.; Xuan, X. H.; Zhao, J.; Sun, W.; Liang, C.

    2016-12-01

    The wear properties of Mg97Zn1Y2 alloy were investigated using the pin-on-disk wear machine within a load range of 20-380 N and a sliding speed range of 0.2-4.0 m/s. Analysis of worn surfaces using scanning electron microscope and energy-dispersive x-ray spectrometer revealed that wear mechanisms including abrasion + oxidation, delamination accompanied by heavy surface oxidation and delamination operated in mild wear regime, while wear mechanisms such as severe plastic deformation, severe plastic deformation accompanied by spallation of oxidation layer and surface melting prevailed in severe wear regime. The microstructural evolution and hardness change in subsurfaces were examined by optical microscopy and hardness tester. The transformation of surface material from the deformed into dynamic recrystallization (DRX) microstructure was observed before and after mild-to-severe transition. The reason for mild-to-severe wear transition was identified as the transformation of strain hardening to DRX softening in subsurface. Mg97Zn1Y2 alloy has a superior mild-to-severe wear transition resistance to AZ alloys because of its higher recrystallization temperature. A novel model for evaluating the critical surface temperature of mild-to-severe wear transition was established using DRX kinetics.

  18. Wear Resistance of 3D Printing Resin Material Opposing Zirconia and Metal Antagonists.

    PubMed

    Park, Ji-Man; Ahn, Jin-Soo; Cha, Hyun-Suk; Lee, Joo-Hee

    2018-06-20

    3D printing offers many advantages in dental prosthesis manufacturing. This study evaluated the wear resistance of 3D printing resin material compared with milling and conventional resin materials. Sixty substrate specimens were prepared with three types of resin materials: 3D printed resin, milled resin, and self-cured resin. The 3D printed specimens were printed at a build angle of 0° and 100 μm layer thickness by digital light processing 3D printing. Two kinds of abraders were made of zirconia and CoCr alloy. The specimens were loaded at 5 kg for 30,000 chewing cycles with vertical and horizontal movements under thermocycling condition. The 3D printed resin did not show significant difference in the maximal depth loss or the volume loss of wear compared to the milled and the self-cured resins. No significant difference was revealed depending on the abraders in the maximal depth loss or the volume loss of wear. In SEM views, the 3D printed resin showed cracks and separation of inter-layer bonds when opposing the metal abrader. The results suggest that the 3D printing using resin materials provides adequate wear resistance for dental use.

  19. Effect of Laser Remelting on Friction-Wear Behaviors of Cold Sprayed Al Coatings in 3.5% NaCl Solution.

    PubMed

    Jing, Zhang; Dejun, Kong

    2018-02-11

    of 1.5 N is abrasive wear and fatigue wear; while that after LR is abrasive wear and fatigue wear, with no corrosion wear, showing that LR improves its corrosion and wear resistance.

  20. Wear-reducing Surface Functionalization of Implant Materials Using Ultrashort Laser Pulses

    NASA Astrophysics Data System (ADS)

    Oldorf, P.; Peters, R.; Reichel, S.; Schulz, A.-P.; Wendlandt, R.

    The aim of the project called "EndoLas" is the development of a reproducible and reliable method for a functionalization of articulating surfaces on hip joint endoprostheses due to a reduction of abrasion and wear by the generation of micro structures using ultrashort laser pulses. On the one hand, the microstructures shall ensure the capture of abraded particles, which cause third-body wear and thereby increase aseptic loosening. On the other hand, the structures shall improve or maintain the tribologically important lubricating film. Thereby, the cavities serve as a reservoir for the body's own synovial fluid. The dry friction, which promotes abrasion and is a part of the mixed friction in the joint, shall therefore be reduced. In experimental setups it was shown, that the abrasive wear can be reduced significantly due to micro-structuring the articulating implant surfaces. To shape the fine and deterministic cavities on the surfaces, an ultra-short pulsed laser, which is integrated in a high-precision, 5-axes micro-machining system, was used. The laser system, based on an Yb:YAG thin-disk regenerative amplifier, has an average output power of 50 W at the fundamental wavelength of 1030 nm, a maximum repetition rate of 400 kHz and a pulse duration of 6 ps. Due to this, a maximum pulse energy of 125 μJ is achievable. Furthermore external second and third harmonic generation enables the usage of wavelengths in the green and violet spectral range.

  1. Wear resistance and compression strength of ceramics tested in fluoride environments.

    PubMed

    Theodoro, Guilherme Teixeira; Fiorin, Lívia; Moris, Izabela Cristina Maurício; Rodrigues, Renata Cristina Silveira; Ribeiro, Ricardo Faria; Faria, Adriana Cláudia Lapria

    2017-01-01

    Dental ceramics have been widely used because of aesthetic, but wear is still questioned. There are relates that ceramic surface is prone to degradation by acidulated fluoride, that can increase wear rates. The aim of this study was to evaluate the effect of neutral and acidulated fluoride gel, used as preventive agents for professional use, at wear and compression strength of dental ceramics IPS e.max ZirPress (ZIR), IPS Empress Esthetic (EMP) e IPS Inline POM (POM). For this, 30 crowns and 30 disks were obtained by heat-pressing. Crowns and disks were submitted to two-body wear test at machine of mechanical loading, simulating occlusion, lateral movement and disocclusion. It was performed 300,000 cycles at 1Hz frequency under 20N load, to simulate 1 year of mastication. Samples were totally immersed during the test and were divided into three groups according to the gel used for immersion (n=10): control, neutral (sodium fluoride 2%) and acidulated (acidulated phosphate fluoride 1.23%). Samples (crowns and disks) were analyzed for vertical height loss after the test using, respectively, profile projector and stereomicroscope. Roughness of worn surface of crowns and disks was evaluated by laser confocal microscopy. Data of height loss and roughness were evaluated by two-way ANOVA and Bonferroni's test. A crown/disk of each group was analyzed by scanning electronic microscopy. After wear resistance tests, crowns were cemented to their abutments and submitted to compressive load at 30° angulation and 1mm/min speed. Type of failures was compared by qui-square test. Ceramic EMP worn less while ZIR worn more. Control gel worn more at crowns while acidulated gel worn more at disks. Surface roughness of samples tested at acidulated gel was significantly lower. Type of failures found at compression resistance tests was affected by ceramic type, but not by gel used. The results suggest that ceramic and fluoride gel affect wear and roughness of worn surface while type of

  2. Technology for improving the wear resistance of aggregates by materials impregnation

    DOT National Transportation Integrated Search

    1981-08-01

    The use of impregnation as a means of improving the wear resistance of natural aggregates was investigated. A series of tests were conducted using four aggregates of varying quality, selected from a sampling of 40 different aggregates. Tests performe...

  3. An investigation on dry sliding wear behaviour of AA6061-AlNp composite

    NASA Astrophysics Data System (ADS)

    Mahesh Naidu, K.; Mohan Reddy, Chandra

    2018-03-01

    This paper studies the effect of load, sliding distance, reinforcement percentage and temperature on dry sliding wear behaviour of Al-AlNp composites by using pin on disc machine. The wear test was conducted at different loads (1,2,3 & 4 Kg), temperatures (30°C, 100°C, 170°C & 240°C) and sliding distances (500m,1000m,1500m and 2000m). Increase in wear rate has been observed by increasing the load and sliding distance, at the same time it has been decreased by increasing the reinforcement percentage and temperature. At the higher loads, temperatures and sliding distances adhesive wear, abrasive wear and oxidation wear are observed to be dominant modes of wear mechanisms in the composite.

  4. The inter-relationship between dietary and environmental properties and tooth wear: comparisons of mesowear, molar wear rate, and hypsodonty index of extant Sika deer populations.

    PubMed

    Kubo, Mugino Ozaki; Yamada, Eisuke

    2014-01-01

    In reference to the evolutionary trend of increasing cheek tooth height in herbivorous ungulates, the causes of dental abrasion have long been debated. Interspecific comparisons of extant ungulates have revealed that both phytoliths in grass and external abrasive matter may play important roles. Using analysis of extant sika deer living in various environments and showing continuous latitudinal variation in food habits from northern grazing to southern browsing, we quantitatively evaluated the influence of dietary and environmental properties on three dental variables: mesowear score (MS), molar wear rate, and M3 hypsodonty index. We used 547 skulls and 740 mandibles from 16 populations of sika deer to obtain the dental measurements. We found that only graminoid proportion in diet correlated with MS and the molar wear rate, implying that phytoliths in grass abrade dental tissues. In contrast, annual precipitation in habitat was not correlated with any of the dental variables. We also found a significant correlation between the molar wear rate (selective pressure for high-crowned molars) and the M3 hypsodonty index of extant sika deer, implying an evolutionary increment in molar height corresponding to the molar wear rate. Our intraspecific comparative analyses provide further support for use of mesowear analysis as a paleodiet estimation method; it not only reveals staple food types (graminoids or dicots) but also implies regional or seasonal variation in the diet of the species.

  5. The Inter-Relationship between Dietary and Environmental Properties and Tooth Wear: Comparisons of Mesowear, Molar Wear Rate, and Hypsodonty Index of Extant Sika Deer Populations

    PubMed Central

    Kubo, Mugino Ozaki; Yamada, Eisuke

    2014-01-01

    In reference to the evolutionary trend of increasing cheek tooth height in herbivorous ungulates, the causes of dental abrasion have long been debated. Interspecific comparisons of extant ungulates have revealed that both phytoliths in grass and external abrasive matter may play important roles. Using analysis of extant sika deer living in various environments and showing continuous latitudinal variation in food habits from northern grazing to southern browsing, we quantitatively evaluated the influence of dietary and environmental properties on three dental variables: mesowear score (MS), molar wear rate, and M3 hypsodonty index. We used 547 skulls and 740 mandibles from 16 populations of sika deer to obtain the dental measurements. We found that only graminoid proportion in diet correlated with MS and the molar wear rate, implying that phytoliths in grass abrade dental tissues. In contrast, annual precipitation in habitat was not correlated with any of the dental variables. We also found a significant correlation between the molar wear rate (selective pressure for high-crowned molars) and the M3 hypsodonty index of extant sika deer, implying an evolutionary increment in molar height corresponding to the molar wear rate. Our intraspecific comparative analyses provide further support for use of mesowear analysis as a paleodiet estimation method; it not only reveals staple food types (graminoids or dicots) but also implies regional or seasonal variation in the diet of the species. PMID:24603896

  6. Microstructures and Dry Sliding Wear Resistance of the Laser Ceramics Composite Coating on Pure Ti

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Zhang, Yuanbin; Luo, Hui; Huo, Yushuang

    2012-06-01

    In this study, Al-Ti-Co was used to improve the surface performance of pure Ti. Laser cladding is an important surface modification technique, which can be used to improve the surface performance of pure Ti. Laser cladding of the Al-Ti-Co + TiB2 pre-placed powders on pure Ti can form ceramics reinforced the composite coating, which improved the wear resistance of the substrate. Characteristics of the composite coating were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness and wear tests. And the laser-cladded coating can also have major dilution from the substrate. Due to the action of the fine grain strengthening and the phase constituent, the wear resistance and microhardness of pure Ti surface were greatly improved.

  7. Floor tile glass-ceramic glaze for improvement of the resistance to surface abrasion

    NASA Astrophysics Data System (ADS)

    Gajek, M.; Lis, J.; Partyka, J.; Wójczyk, M.

    2011-10-01

    The results of research aimed at the study on frits and glass-ceramic glazes for floor tiles, based on compositions located in the primary field of cordierite crystallization within the system MgO-Al2O3-SiO2, have been presented. The results comprise investigations on the frits crystallization abilities, stability of the crystallizing phase under conditions of single-stage a fast firing cycle (time below 60 minutes) depending on their chemical composition and the influence of the nucleation agents. The influence of the nucleating agents namely TiO2, ZrO2, V2O5 on phase composition of obtained crystalline glazes, mechanical parameters and microstructure, has been examined. The strength tests proved increased mechanical resistance of crystalline glazes. Obtained glazes are characterized by high microhardness in range 6~8 GPa, as well as the increased wear resistance measured by the loss of weight below 100 mg / 55 cm2 (PN-EN ISO 10545-7). Significant increase of these parameters as compared with non-crystalline glazes, where micro-hardness values range between 5~6 GPa and the wear resistance values range from 120 to 200 mg, has been proved. Starting glasses (frits) and glazes of the ternary system MgO-SiO2-Al2O3, were examined with use of DTA, XRD and SEM methods.

  8. High Strength and Wear Resistant Aluminum Alloy for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    In this paper, a new high strength and wear resistant aluminum cast alloy invented by NASA-MSFC for high temperature applications will be presented. Developed to meet U.S. automotive legislation requiring low-exhaust emission, the novel NASA 398 aluminum-silicon alloy offers dramatic improvement in tensile and fatigue strengths at elevated temperatures (500 F-800 F), enabling new pistons to utilize less material, which can lead to reducing part weight and cost as well as improving performance. NASA 398 alloy also offers greater wear resistance, surface hardness, dimensional stability, and lower thermal expansion compared to conventional aluminum alloys for several commercial and automotive applications. The new alloy can be produced economically using permanent steel molds from conventional gravity casting or sand casting. The technology was developed to stimulate the development of commercial aluminum casting products from NASA-developed technology by offering companies the opportunity to license this technology.

  9. Dental Wear: A Scanning Electron Microscope Study

    PubMed Central

    Levrini, Luca; Di Benedetto, Giulia

    2014-01-01

    Dental wear can be differentiated into different types on the basis of morphological and etiological factors. The present research was carried out on twelve extracted human teeth with dental wear (three teeth showing each type of wear: erosion, attrition, abrasion, and abfraction) studied by scanning electron microscopy (SEM). The study aimed, through analysis of the macro- and micromorphological features of the lesions (considering the enamel, dentin, enamel prisms, dentinal tubules, and pulp), to clarify the different clinical and diagnostic presentations of dental wear and their possible significance. Our results, which confirm current knowledge, provide a complete overview of the distinctive morphology of each lesion type. It is important to identify the type of dental wear lesion in order to recognize the contributing etiological factors and, consequently, identify other more complex, nondental disorders (such as gastroesophageal reflux, eating disorders). It is clear that each type of lesion has a specific morphology and mechanism, and further clinical studies are needed to clarify the etiological processes, particularly those underlying the onset of abfraction. PMID:25548769

  10. Impact Capacity Reduction in Railway Prestressed Concrete Sleepers with Surface Abrasions

    NASA Astrophysics Data System (ADS)

    Ngamkhanong, Chayut; Li, Dan; Kaewunruen, Sakdirat

    2017-10-01

    Railway sleepers (also called ‘railroad tie’ in North America) embedded in ballasted railway tracks are a main part of railway track structures. Its important role is to transfer the loads evenly from the rails to a wider area of ballast bed and to secure rail gauge and enable safe passages of rolling stocks. By nature, railway infrastructure is nonlinear, evidenced by its behaviours, geometry and alignment, wheel-rail contact and operational parameters such as tractive efforts. Based on our critical review, the dynamic behaviour of railway sleepers has not been fully investigated, especially when the sleepers are deteriorated by excessive wears. In fact, the ballast angularity causes differential abrasions on the soffit or bottom surface of sleepers (especially at railseat zone). Furthermore, in sharp curves and rapid gradient change, longitudinal and lateral dynamics of rails increase the likelihood of railseat abrasions in concrete sleepers due to the unbalanced loading conditions. This paper presents a structural capacity of concrete sleepers under dynamic transient loading. The modified compression field theory for ultimate strength design of concrete sleepers under impact loading will be highlighted in this study. The influences of surface abrasions, including surface abrasion and soffit abrasion, on the dynamic behaviour of prestressed concrete sleepers, are firstly highlighted. The outcome of this study will improve the rail maintenance and inspection criteria in order to establish appropriate and sensible remote track condition monitoring network in practice. Moreover, this study will also improve the understanding of the fundamental dynamic behaviour of prestressed concrete sleepers with surface abrasions. The insight into these behaviours will not only improve safety and reliability of railway infrastructure but will enhance the structural safety of other concrete structures.

  11. Wear resistance of a modified polymethyl methacrylate artificial tooth compared to five commercially available artificial tooth materials.

    PubMed

    Kamonwanon, Pranithida; Yodmongkol, Sirasa; Chantarachindawong, Rojcharin; Thaweeboon, Sroisiri; Thaweeboon, Boonyanit; Srikhirin, Toemsak

    2015-08-01

    Wear resistance is a limitation of artificial denture teeth. Improving the wear resistance of conventional artificial denture teeth is of value to prosthodontic patients. The purpose of this in vitro study was to evaluate the wear resistance and hardness of modified polymethyl methacrylate artificial denture teeth compared to 5 commercially available artificial tooth materials. This study evaluated 180 artificial denture teeth (6 groups) that included 3 groups of conventional artificial teeth (MajorDent, Cosmo HXL, and Gnathostar), 2 groups of composite resin artificial teeth (Endura and SR Orthosit PE), and 1 group of modified surface artificial teeth. The flattened buccal surface of each tooth (n=15) was prepared for investigation with the Vickers hardness test and the elucidate wear test (n=15) by using a brushing machine. Each group was loaded for 18,000 cycles, at 2 N, and 150 rpm. The wear value was identified with a profilometer. The data were statistically analyzed by using 1-way ANOVA and post hoc Turkey honestly significant difference tests (α=.001). The tribologies were observed under a scanning electron microscope, and the cytotoxicities were evaluated by MTT assay. The Vickers hardnesses ranged from 28.48 to 39.36. The wear depths and worn surface area values ranged from 1.12 to 10.79 μm and from 6.74 to 161.95 μm(2). The data revealed that the modified artificial denture teeth were significantly harder and exhibited significantly higher wear resistance than did the conventional artificial teeth (P<.001). The scanning electron microscopic images revealed cross sections of the conventional artificial denture teeth with intensively worn surface areas after brushing. The cytotoxicity test revealed 97.85% cell viability, which indicates the nontoxicity of the modified surface of this material. Within the limitations of this study, the polymethyl methacrylate modified surface artificial denture teeth was not significantly different from that of the

  12. Tantalum-based thin film coatings for wear resistant arthroprostheses.

    PubMed

    Balagna, C; Faga, M G; Spriano, S

    2011-10-01

    Cobalt-chromium-molybdenum alloys with high carbon content (HC-CoCrMo) are widely used as materials for arthroprosthesis, in particular in metal-on-metal (MoM) hip joints. In spite of their good wear and corrosion resistance, production of metallic wear particles and metal ion release will occur on a large time-scale. An enhancement of the metal ion level in the patient's blood and urine is often reported in clinical data. Hypersensitivity, inflammatory response and cell necrosis can occur as consequence. So implants on young patients and women on childbearing age are not so widespread. The aim of this research is the realization of a thin film coating in order to improve the biocompatibility of Co-based alloys and to reduce debris production, ion release and citotoxicity. The innovative process consists of a thermal treatment in molten salts, in order to obtain a tantalum enriched thin film coating. Tantalum is chosen because it is considered a biocompatible metal with high corrosion resistance and low ion release. Three HC-CoCrMo alloys, produced by different manufacturing processes, are tested as substrates. The coating is a thin film of TaC or it can be composed by a multilayer of two tantalum carbides and metallic tantalum, depending on the temperature of the treatment and on the carbon content of the substrate. The thin films as well the substrates are characterized from the structural, chemical and morphological point of view. Moreover mechanical behaviour of treated and untreated materials is analyzed by means of nanohardness, scratch and ball-on-disc wear tests. The coating increases the mechanical and tribological properties of HC-CoCrMo.

  13. Wear, strength, modulus and hardness of CAD/CAM restorative materials.

    PubMed

    Lawson, Nathaniel C; Bansal, Ritika; Burgess, John O

    2016-11-01

    To measure the mechanical properties of several CAD/CAM materials, including lithium disilicate (e.max CAD), lithium silicate/zirconia (Celtra Duo), 3 resin composites (Cerasmart, Lava Ultimate, Paradigm MZ100), and a polymer infiltrated ceramic (Enamic). CAD/CAM blocks were sectioned into 2.5mm×2.5mm×16mm bars for flexural strength and elastic modulus testing and 4mm thick blocks for hardness and wear testing. E.max CAD and half the Celtra Duo specimens were treated in a furnace. Flexural strength specimens (n=10) were tested in a three-point bending fixture. Vickers microhardness (n=2, 5 readings per specimen) was measured with a 1kg load and 15s dwell time. The CAD/CAM materials as well as labial surfaces of human incisors were mounted in the UAB wear device. Cusps of human premolars were mounted as antagonists. Specimens were tested for 400,000 cycles at 20N force, 2mm sliding distance, 1Hz frequency, 24°C, and 33% glycerin lubrication. Volumetric wear and opposing enamel wear were measured with non-contact profilometry. Data were analyzed with 1-way ANOVA and Tukey post-hoc analysis (alpha=0.05). Specimens were observed with SEM. Properties were different for each material (p<0.01). E.max CAD and Celtra Duo were generally stronger, stiffer, and harder than the other materials. E.max CAD, Celtra Duo, Enamic, and enamel demonstrated signs of abrasive wear, whereas Cerasmart, Lava Ultimate, Paradigm MZ100 demonstrated signs of fatigue. Resin composite and resin infiltrated ceramic materials have demonstrated adequate wear resistance for load bearing restorations, however, they will require at least similar material thickness as lithium disilicate restorations due to their strength. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. Adhesive Wear Performance of CFRP Multilayered Polyester Composites Under Dry/wet Contact Conditions

    NASA Astrophysics Data System (ADS)

    Danaelan, D.; Yousif, B. F.

    The tribo-performance of a new engineering composite material based on coconut fibers was investigated. In this work, coconut fibers reinforced polyester (CFRP) composites were developed. The tribo-experiments were conducted by using pin-on-disc machine under dry and wet sliding contact condition against smooth stainless steel counterface. Worn surfaces were observed using optical microscope. Friction coefficient and specific wear rate were presented as a function of sliding distance (0-0.6 km) at different sliding velocities (0.1-0.28 m/s). The effect of applied load and sliding velocity was evaluated. The results showed that all test parameters have significant influence on friction and wear characteristics of the composites. Moreover, friction coefficient increased as the normal load and speed increased, the values were about 0.7-0.9 under dry contact condition. Meanwhile, under wet contact condition, there was a great reduction in the friction coefficient, i.e. the values were about 0.1-0.2. Furthermore, the specific wear rates were found to be around 2-4 (10-3) mm3/Nm under dry contact condition and highly reduced under wet condition. In other words, the presence of water as cleaner and polisher assisted to enhance the adhesive wear performance of CFRP by about 10%. The images from optical microscope showed evidence of adhesive wear mode with transition to abrasive wear mode at higher sliding velocities due to third body abrasion. On the other hand, optical images for wet condition showed less adhesive wear and smooth surfaces.

  15. Microstructure Characterization and Wear-Resistant Properties Evaluation of an Intermetallic Composite in Ni-Mo-Si System.

    PubMed

    Huang, Boyuan; Song, Chunyan; Liu, Yang; Gui, Yongliang

    2017-02-04

    Intermetallic compounds have been studied for their potential application as structural wear materials or coatings on engineering steels. In the present work, a newly designed intermetallic composite in a Ni-Mo-Si system was fabricated by arc-melting process with commercially pure metal powders as starting materials. The chemical composition of this intermetallic composite is 45Ni-40Mo-15Si (at %), selected according to the ternary alloy diagram. The microstructure was characterized using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS), and the wear-resistant properties at room temperature were evaluated under different wear test conditions. Microstructure characterization showed that the composite has a dense and uniform microstructure. XRD results showed that the intermetallic composite is constituted by a binary intermetallic compound NiMo and a ternary Mo₂Ni₃Si metal silicide phase. Wear test results indicated that the intermetallic composite has an excellent wear-resistance at room-temperature, which is attributed to the high hardness and strong atomic bonding of constituent phases NiMo and Mo₂Ni₃Si.

  16. Establishment of Wear Resistant HVOF Coatings for 50CrMo4 Chromium Molybdenum Alloy Steel as an Alternative for Hard Chrome Plating

    NASA Astrophysics Data System (ADS)

    Karuppasamy, S.; Sivan, V.; Natarajan, S.; Kumaresh Babu, S. P.; Duraiselvam, M.; Dhanuskodi, R.

    2018-05-01

    High cost imported components of seamless steel tube manufacturing plants wear frequently and need replacement to ensure the quality of the product. Hard chrome plating, which is time consuming and hazardous, is conventionally used to restore the original dimension of the worn-out surface of the machine components. High Velocity Oxy-Fuel (HVOF) thermal spray coatings with NiCrBSi super alloy powder and Cr3C2 NiCr75/25 alloy powder applied on a 50CrMo4 (DIN-1.7228) chromium molybdenum alloy steel, the material of the wear prone machine component, were evaluated for use as an alternative for hard chrome plating in this present work. The coating characteristics are evaluated using abrasive wear test, sliding wear test and microscopic analysis, hardness test, etc. The study results revealed that the HVOF based NiCrBSi and Cr3C2NiCr75/25 coatings have hardness in the range of 800-900 HV0.3, sliding wear rate in the range of 50-60 µm and surface finish around 5 microns. Cr3C2 NiCr75/25 coating is observed to be a better option out of the two coatings evaluated for the selected application.

  17. Tooth wear and wear investigations in dentistry.

    PubMed

    Lee, A; He, L H; Lyons, K; Swain, M V

    2012-03-01

    Tooth wear has been recognised as a major problem in dentistry. Epidemiological studies have reported an increasing prevalence of tooth wear and general dental practitioners see a greater number of patients seeking treatment with worn dentition. Although the dental literature contains numerous publications related to management and rehabilitation of tooth wear of varying aetiologies, our understanding of the aetiology and pathogenesis of tooth wear is still limited. The wear behaviour of dental biomaterials has also been extensively researched to improve our understanding of the underlying mechanisms and for the development of restorative materials with good wear resistance. The complex nature of tooth wear indicates challenges for conducting in vitro and in vivo wear investigations and a clear correlation between in vitro and in vivo data has not been established. The objective was to critically review the peer reviewed English-language literature pertaining to prevalence and aetiology of tooth wear and wear investigations in dentistry identified through a Medline search engine combined with hand-searching of the relevant literature, covering the period between 1960 and 2011. © 2011 Blackwell Publishing Ltd.

  18. A nanometric cushion for enhancing scratch and wear resistance of hard films

    PubMed Central

    Gotlib-Vainshtein, Katya; Girshevitz, Olga; Barlam, David

    2014-01-01

    Summary Scratch resistance and friction are core properties which define the tribological characteristics of materials. Attempts to optimize these quantities at solid surfaces are the subject of intense technological interest. The capability to modulate these surface properties while preserving both the bulk properties of the materials and a well-defined, constant chemical composition of the surface is particularly attractive. We report herein the use of a soft, flexible underlayer to control the scratch resistance of oxide surfaces. Titania films of several nm thickness are coated onto substrates of silicon, kapton, polycarbonate, and polydimethylsiloxane (PDMS). The scratch resistance measured by scanning force microscopy is found to be substrate dependent, diminishing in the order PDMS, kapton/polycarbonate, Si/SiO2. Furthermore, when PDMS is applied as an intermediate layer between a harder substrate and titania, marked improvement in the scratch resistance is achieved. This is shown by quantitative wear tests for silicon or kapton, by coating these substrates with PDMS which is subsequently capped by a titania layer, resulting in enhanced scratch/wear resistance. The physical basis of this effect is explored by means of Finite Element Analysis, and we suggest a model for friction reduction based on the "cushioning effect” of a soft intermediate layer. PMID:25161836

  19. Scanning electron microscopy of dentition: methodology and ultrastructural morphology of tooth wear.

    PubMed

    Shkurkin, G V; Almquist, A J; Pfeihofer, A A; Stoddard, E L

    1975-01-01

    Scanning electron micrographs were taken of sets of human molars-those of paleo-Indians used in mastication of, ostensibly, a highly abrasive diet, and those of contemporary Americans. Different ultrastructural patterns of enamel wear were observed between the groups.

  20. Effects of Synchronous Rolling on Microstructure, Hardness, and Wear Resistance of Laser Multilayer Cladding

    NASA Astrophysics Data System (ADS)

    Zhao, W.; Zha, G. C.; Xi, M. Z.; Gao, S. Y.

    2018-03-01

    A synchronous rolling method was proposed to assist laser multilayer cladding, and the effects of this method on microstructure, microhardness, and wear resistance were studied. Results show that the microstructure and mechanical properties of the traditional cladding layer exhibit periodic inhomogeneity. Synchronous rolling breaks the columnar dendrite crystals to improve the uniformity of the organization, and the residual plastic energy promotes the precipitation of strengthening phases, as CrB, M7C3, etc. The hardness and wear resistance of the extruded cladding layer increase significantly because of the grain refinement, formation of dislocations, and dispersion strengthening. These positive significances of synchronous rolling provide a new direction for laser cladding technology.

  1. Grading technologies for the manufacture of innovative cutting blades

    NASA Astrophysics Data System (ADS)

    Rostek, Tim; Homberg, Werner

    2018-05-01

    Cutting blades for harvesting applications are used in a variety of agricultural machines. These parts are in contact with highly abrasive lawn clippings and often wear out within hours which results in high expensive re-sharpening maintenance. This paper relates to manufacturing techniques enhancing the durability of cutting blades based on a structural analysis of the prevailing wear mechanisms containing chipping and abrasive wear. Each mechanism results in specific demands on the cutting edge's mechanical characteristics. The design of evaluation methods respectively is one issue of the paper. This is basis for approaches to improve the cutting edge performance on purpose. On option to improve abrasive wear resistance and, thus, service life is the application of locally graded steel materials as semi-finished products for self-sharpening cutting blades. These materials comprise a layered structure consisting of a hard, wear resistant layer and a relatively softer layer which is lesser wear resistant. As the cutting blade is subjected to wear conditions, the less wear resistant layer wears faster than the relatively more wear resistant harder layer revealing a durable cross section of the cutting edge and, thus, cutting performance. Anyways, chipping is another key issue on the cutting edge's lifetime. Here, the cutting edges cross section by means of geometry and grind respectively as well as its mechanical properties matter. FEM analysis reveal innovative options to optimize the cross section of the blade as well as thermomechanical strengthening add further strength to reduce chipping. This paper contains a comprehensive strategy to improve cutting blades with use of innovative manufacturing technologies which apply application-specific graded mechanical characteristics and, thus, significantly improved performance characteristics.

  2. Backside wear in modern total knee designs.

    PubMed

    Jayabalan, Prakash; Furman, Bridgette D; Cottrell, Jocelyn M; Wright, Timothy M

    2007-02-01

    Although modularity affords various options to the orthopedic surgeon, these benefits come at a price. The unintended bearing surface between the back surface of the tibial insert and the metallic tray results in micromotion leading to polyethylene wear debris. The objective of this study was to examine the backside wear of tibial inserts from three modern total knee designs with very different locking mechanisms: Insall-Burstein II (IB II), Optetrak, and Advance. A random sample of 71 inserts were obtained from our institution's retrieval collection and examined to assess the extent of wear, depth of wear, and wear damage modes. Patient records were also obtained to determine patient age, body mass index, length of implantation, and reason for revision. Modes of wear damage (abrasion, burnishing, scratching, delamination, third body debris, surface deformation, and pitting) were then scored in each zone from 0 to 3 (0 = 0%, 1 = 0-10%, 2 = 10-50%, and 3 = >50%). The depth of wear was subjectively identified as removal of manufacturing identification markings stamped onto the inferior surface of the polyethylene. Both Advance and IB II polyethylene inserts showed significantly higher scores for backside wear than the Optetrak inserts. All IB II and Advance implants showed evidence of backside wear, whereas 17% (5 out of 30) of the retrieved Optetrak implants had no observable wear. There were no significant differences when comparing the depth of wear score between designs. The locking mechanism greatly affects the propensity for wear and should be considered when choosing a knee implant system.

  3. Effect of Laser Remelting on Friction-Wear Behaviors of Cold Sprayed Al Coatings in 3.5% NaCl Solution

    PubMed Central

    Jing, Zhang; Dejun, Kong

    2018-01-01

    of 1.5 N is abrasive wear and fatigue wear; while that after LR is abrasive wear and fatigue wear, with no corrosion wear, showing that LR improves its corrosion and wear resistance. PMID:29439485

  4. Development of wear resistant NFSS-HA novel biocomposites and study of their tribological properties for orthopaedic applications.

    PubMed

    Younesi, M; Bahrololoom, M E; Fooladfar, H

    2010-02-01

    Implants made of nickel free austenitic stainless steel can reduce the toxic effect of released nickel ion and compounds from the conventional stainless steels. On the other hand, hydroxyapatite is a ceramic which has been used in orthopaedic applications due to its good osteoconductivity, biocompatibility and bioactivity. However, there is no evidence in the literature up to now on producing composites based on nickel free stainless steel and hydroxyapatite and study of their tribology. The aim of this work was to produce novel biocomposites made up of nickel free stainless steel with hydroxyapatite (prepared by heat treating bone ash) and studying their tribology under various loads in air and in Ringer's physiological solution. Different amounts of hydroxyapatite powder (10, 20, 30 and 40% Vol.) were added to this nickel free stainless steel powder to get the biocomposites. Variation of their density, hardness, wear resistance and friction with the ceramic (hydroxyapatite) content and wear load were investigated in air and in Ringer's solution. The density of the composites was decreased by increasing the volume percentage of the hydroxyapatite, while wear resistance of the composites was increased. The wear mechanism of these composites was changed by increasing the wear load and consequently the volume loss was enhanced dramatically. Furthermore, by increasing the sliding distance, the rate of volume loss was decreased slightly. The friction coefficient of the composites was also decreased by increasing the weight percentage of hydroxyapatite. Effect of the physiological Ringer's solution on wear resistance and friction coefficient of the composites was nearly negligible. The wear mechanisms of the samples were identified by studying the SEM images of the worn surfaces of the tested samples in different wear loads and HA contents. Copyright 2009 Elsevier Ltd. All rights reserved.

  5. Fabrication and Tribological Behavior of Stir Cast Mg/B4C Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Singh, Amandeep; Bala, Niraj

    2017-10-01

    Magnesium-based metal matrix composites (MMMCs) have emerged as good alternative material to conventional materials due to their promising advanced properties. In the present work, magnesium-based metal matrix composites (MMMCs) reinforced with B4C particles were successfully fabricated by cost-effective conventional stir casting technique. MMMCs with an average particle size of 63 µm and different weight percent (wt pct) of B4C between 3 and 12 were fabricated. Wear tests were carried out using a pin-on-disk against a steel disk under dry sliding condition at loads that varied between 1 and 5 kg at fixed sliding velocity of 1 m/s. The wear data clearly showed that wear resistance of cast composites is better than that of unreinforced magnesium, which is attributed to dispersion hardening caused by carbide particles. An increase in wt pct of B4C showed the wear resistance and hardness to increase significantly. The wear rate and coefficient of friction increased with an increase in applied load. The SEM and EDS analysis of the worn surfaces delineated the dominant wear mechanisms to be abrasion, adhesion, and oxidation under the different sliding conditions. At lower loads, the wear mechanism transformed from severe abrasive wear in pure magnesium (Mg) to mild abrasion, slight delamination, and oxidation in the Mg/12 wt pct B4C fabricated composite. At higher loads, severe abrasion, adhesion, delamination, and oxidation were found to be the major wear mechanisms in pure Mg, whereas in the Mg/12 wt pct B4C fabricated composites the corresponding mechanisms were mild abrasion, mild adhesion, slight delamination, and oxidation.

  6. Microstructure and Wear Resistance of Composite Coating by Laser Cladding Al/TiN on the Ti-6Al-4V Substrate

    NASA Astrophysics Data System (ADS)

    Zhang, H. X.; Yu, H. J.; Chen, C. Z.

    2015-05-01

    The composite coatings were fabricated by laser cladding Al/TiN pre-placed powders on Ti-6Al-4V substrate for enhancing wear resistance and hardness of the substrate. The composite coatings were analyzed by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The sliding wear tests were performed by MM200 wear test machine. The hardness of the coatings was tested by HV-1000 hardness tester. After laser cladding, it was found that there was a good metallurgical bond between the coating and the substrate. The composite coatings were mainly composed of the matrix of β-Ti (Al) and the reinforcements of titanium nitride (TiN), Ti3Al, TiAl and Al3Ti. The hardness and wear resistance of the coatings on four samples were greatly improved, among which sample 4 exhibited the highest hardness and best wear resistance. The hardness of the coating on sample 4 was approximately 2.5 times of the Ti-6Al-4V substrate. And the wear resistance of sample 4 was four times of the substrate.

  7. Friction and wear behavior of aluminum and composite I-beam stiffened airplane skins

    NASA Technical Reports Server (NTRS)

    Jackson, K. E.

    1985-01-01

    Friction and wear behavior was determined for I-beam stiffened skins constructed of aluminum, graphite-epoxy composite, and glass hybrid composite under abrasive loading conditions typical of those occurring on the underside of a transport airplane during an emergency belly landing. A test apparatus was developed to abrade the test specimens on actual runway surface under a range of pressures (2-5 psi) and velocities (16-50 mph). These parameters were chosen to fall within the range of conditions typical of an airframe sliding on a runway surface. The effects of the test variables on the wear rate and the coefficient of friction are discussed and comparisons are made between the composite materials and aluminum. In addition, the test apparatus was equipped to monitor the temperature variations on the backside of the skins during abrasion and these results are presented.

  8. Detailed study of oxidation/wear mechanism in lox turbopump bearings

    NASA Technical Reports Server (NTRS)

    Chase, T. J.; Mccarty, J. P.

    1993-01-01

    Wear of 440C angular contact ball bearings of the phase 2 high pressure oxygen turbopump (HPOTP) of the space shuttle main engine (SSME) has been studied by means of various advanced nondestructive techniques (NDT) and modeled with reference to all known material, design, and operation variables. Three modes dominating the wear scenario were found to be the adhesive/sheer peeling (ASP), oxidation, and abrasion. Bearing wear was modeled in terms of the three modes. Lacking a comprehensive theory of rolling contact wear to date, each mode is modeled after well-established theories of sliding wear, while sliding velocity and distance are related to microsliding in ball-to-ring contacts. Microsliding, stress, temperature, and other contact variables are evaluated with analytical software packages of SHABERTH(TM)/SINDA(TM) and ADORE(TM). Empirical constants for the models are derived from NIST experiments by applying the models to the NIST wear data. The bearing wear model so established precisely predicts quite well the average ball wear rate for the HPOTP bearings. The wear rate has been statistically determined for the entire population of flight and development bearings based on Rocketdyne records to date. Numerous illustrations are given.

  9. Three-body-wear resistance of the experimental composites containing filler treated with hydrophobic silane coupling agents.

    PubMed

    Nihei, Tomotaro; Dabanoglu, Alp; Teranaka, Toshio; Kurata, Shigeaki; Ohashi, Katsura; Kondo, Yukishige; Yoshino, Norio; Hickel, Reinhard; Kunzelmann, Karl-Heinz

    2008-06-01

    This paper evaluated the wear resistance of resin composite materials with fillers which were modified with a novel hydrophobic silane coupling agent. The novel silane coupling agent containing hydrophobic phenyl group 3-(3-methoxy-4-methacryloyloxyphenyl)propyltrimethoxysilane (p-MBS) was synthesized. The experimental light-cure hybrid composites containing 85wt% of filler modified with this silane were formulated. Twelve specimens were prepared for the three-body-wear test with the ACTA machine and the collected data were analyzed statistically using a one-way ANOVA and Tukey's multiple comparison test as the post hoc test. The wear of the composites containing fillers treated with p-MBS was significantly lower compared with the composite materials containing fillers pretreated with 3-methacryloyloxypropyltrimethoxysilane or the commercially composites (AP-X and ELS extra low shrinkage) after a wear test for 200,000 cycles (p<0.05). It is suggested that the resin composites containing fillers modified with the novel hydrophobic silane has high wear resistant, because of the coupling layers treated with this silane had an excellent affinity with the base resin and formed a highly hydrophobic layer on the filler surface.

  10. Porosity and wear resistance of flame sprayed tungsten carbide coatings

    NASA Astrophysics Data System (ADS)

    Winarto, Winarto; Sofyan, Nofrijon; Rooscote, Didi

    2017-06-01

    Thermal-sprayed coatings offer practical and economical solutions for corrosion and wear protection of components or tools. To improve the coating properties, heat treatment such as preheat is applied. The selection of coating and substrate materials is a key factor in improving the quality of the coating morphology after the heat treatment. This paper presents the experimental results regarding the effect of preheat temperatures, i.e. 200°C, 300°C and 400°C, on porosity and wear resistance of tungsten carbide (WC) coating sprayed by flame thermal coating. The powders and coatings morphology were analyzed by a Field Emission Scanning Electron Microscope equipped with Energy Dispersive Spectrometry (FE-SEM/EDS), whereas the phase identification was performed by X-Ray diffraction technique (XRD). In order to evaluate the quality of the flame spray obtained coatings, the porosity, micro-hardness and wear rate of the specimens was determined. The results showed that WC coating gives a higher surface hardness from 1391 HVN up to 1541 HVN compared to that of the non-coating. Moreover, the wear rate increased from 0.072 mm3/min. to 0.082 mm3/min. when preheat temperature was increased. Preheat on H13 steel substrate can reduce the percentage of porosity level from 10.24 % to 3.94% on the thermal spray coatings.

  11. Transparent, wear-resistant, superhydrophobic and superoleophobic poly(dimethylsiloxane) (PDMS) surfaces.

    PubMed

    Martin, Samuel; Bhushan, Bharat

    2017-02-15

    Superoleophobic surfaces that exhibit self-cleaning, antifouling, low-drag, and anti-smudge properties with high transparency are of interest in industrial applications including optical devices, solar panels, and self-cleaning windows. In many superoleophobic surfaces created to date, the lack of mechanical durability has been an issue. In this work, for the first time, transparent, wear-resistant, superhydrophobic and superoleophobic surfaces were developed for polydimethylsiloxane (PDMS) using a simple and scalable fabrication technique. PDMS is of importance in biomedical applications as it is biocompatible, chemically stable, and transparent. PDMS was made superhydrophobic either through micropatterning or an applied coating of hydrophobic SiO 2 nanoparticles with a binder of methylphenyl silicone resin. Through the addition of fluorination via fluorosilane, the nanoparticle/binder coating was made superoleophobic. Intermediate steps using ultraviolet-ozone treatment were required for improved deposition and adhesion of the coatings. The effects of surface treatments were examined through contact angle and tilt angle measurements. The coating was found to have re-entrant geometries desirable for superoleophobicity and to exhibit mechanical wear resistance and transparent properties. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Toothbrushing abrasion susceptibility of enamel and dentin bleached with calcium-supplemented hydrogen peroxide gel.

    PubMed

    Borges, A B; Santos, L F T F; Augusto, M G; Bonfiette, D; Hara, A T; Torres, C R G

    2016-06-01

    The objective of this study was to evaluate enamel and dentin susceptibility to toothbrushing abrasion, after bleaching with 7.5% hydrogen peroxide (HP) gel supplemented or not with 0.5% calcium gluconate (Ca). Toothbrushing was performed immediately and 1h after bleaching, with two suspensions (high and low abrasivity). Bovine enamel and dentin specimens were divided into 12 groups (n=10) according to the bleaching gel (with and without Ca), slurry abrasivity (high or low) and elapsed time after bleaching (immediately and after 1h). As control, a group was not bleached, but abraded. The treatment cycle (7 d) consisted of bleaching (1h) and toothbrushing (135 strokes/day) immediatelly or after 1h of artificial saliva exposure. Surface roughness and surface loss (μm) were measured by profilometry and analysed by three-way ANOVA (5%). Surface roughness means were significantly influenced by slurry abrasivity (p<0.0001). For enamel loss, significant triple interaction was observed (p<0.0001). HP-bleached groups and immediately brushed with high-abrasive slurry exhibited increased loss (1.41±0.14) compared to other groups (μm). Control and HP+Ca-bleached groups brushed after 1h with low abrasive slurry presented the lowest loss (0.21±0.03/0.27±0.02). For dentin loss, significant interaction was observed for bleaching and interval factors (p<0.001). 7.5%HP-bleached groups and immediately brushed showed significantly higher loss (8.71±2.45) than the other groups. It was concluded that surface roughness increased when high abrasive was used, independently of bleaching. 7.5%HP increased enamel and dentin loss, mainly with high abrasive slurries. Calcium supplementation of bleaching gel reduced surface loss. Additionally, in order to minimize tooth wear susceptibility, it is recommended to delay brushing after bleaching. After bleaching gel application, postponing toothbrushing is recommended, as well as brushing with low abrasive dentifrices. Additionally

  13. Microstructure and Dry Sliding Wear Resistance of Laser Cladding Ti-Al-Si Composite Coating

    NASA Astrophysics Data System (ADS)

    Zhang, H. X.; Yu, H. J.; Chen, C. Z.; Dai, J. J.

    In order to improve the wear resistance of Ti alloys, different mass ratios of Ti-Si-Al powders were designed to fabricate hard phases reinforced intermetallic matrix composite coatings on the Ti-6Al-4V substrate by laser cladding. The corresponding coatings were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and high resolution transmission microscopy (HRTEM). The HV-1000 hardness tester and MM200 wear test machine were employed to test the hardness and the wear resistance of the composite coatings, respectively. The composite coatings mainly consisted of the reinforcements of Ti5Si3, Ti3AlC2 and Ti7Al5Si12 and the matrix of Ti3Al, TiAl, TiAl3 and α-Ti. The micro-hardness of the Ti-35Al-15Si coating was from 956 HV0.2 to 1130 HV0.2, which was approximately 3-4 times of the substrate and the highest in the three samples. The wear rate of the Ti-35Al-15Si coating was 0.023cm3ṡmin-1, which was about 1/4 of the Ti-6Al-4V substrate. It was the lowest in the three samples.

  14. Laser surface modification of Ti--6Al--4V: wear and corrosion characterization in simulated biofluid.

    PubMed

    Singh, Raghuvir; Kurella, A; Dahotre, Narendra B

    2006-07-01

    Laser surface melting (LSM) of Ti-6Al-4V is performed in argon to improve its properties, such as microstructure, corrosion, and wear for biomedical applications. Corrosion behavior is investigated by conducting electrochemical polarization experiments in simulated body fluid (Ringer's solution) at 37 C. Wear properties are evaluated in Ringer's solution using pin-on-disc apparatus at a slow speed. Untreated Ti-6Al-4V contains alpha+beta phase. After laser surface melting, it transforms to acicular alpha embedded in the prior beta matrix. Grain growth in the range of 65-89 microm with increase in laser power from 800 to 1500 W due to increase in associated temperature is observed. The hardness of as-laserprocessed Ti-6Al-4V alloy is more (275-297 HV) than that of the untreated alloy (254 HV). Passivation currents are significantly reduced to < 4.3 microA/cm2 after laser treatment compared to untreated Ti-6Al-4V (approximately 12 microA/cm2). The wear resistance of laser-treated Ti-6Al-4V in simulated body fluid is enhanced compared to that of the untreated one. It is the highest for the one that is processed at a laser power of 800 W. Typical micro-cutting features of abrasive wear is the prominent mechanism of wear in both untreated and as-laser-treated Ti-6Al-4V. Fragmentation of wear debris assisted by microcracking was responsible for mass loss during the wear of untreated Ti-6Al-4V in Ringer's solution.

  15. Microstructures and Mechanical Properties of a Wear-Resistant Alloyed Ductile Iron Austempered at Various Temperatures

    NASA Astrophysics Data System (ADS)

    Cui, Junjun; Chen, Liqing

    2015-08-01

    To further improve the mechanical performance of a new type of alloyed bainitic wear-resistant ductile iron, the effects of the various austempering temperatures have been investigated on microstructure and mechanical behaviors of alloyed ductile iron Fe-3.50C-1.95Si-3.58Ni-0.71Cu-0.92Mo-0.65Cr-0.36Mn (in weight percent). This alloyed ductile iron were firstly austenitized at 1123 K (850 °C) for 1 hour and then austempered in a salt bath at 548 K, 573 K, and 598 K (275 °C, 300 °C, and 325 °C) for 2 hours according to time-temperature-transformation diagram calculated by JMatPro software. The microstructures of austempered wear-resistant ductile irons consist of matrix of dark needle-like ferrite plus bright etching austenite and some amount of martensite and some dispersed graphite nodules. With increasing the austempering temperature, the amount of ferrite decreases in austempered ductile iron, while the amount of austenite and carbon content of austenite increases. There is a gradual decrease in hardness and increase in compressive strength with increasing austempering temperature. The increased austenite content and coarsened austenite and ferrite can lead to a hardness decrease as austempering temperature is increased. The increased compressive strength can be attributed to a decreased amount of martensitic transformation. The alloyed ductile iron behaves rather well wear resistance when the austempering is carried out at 598 K (325 °C) for 2 hours. Under the condition of wear test by dry sand/rubber wheel, the wear mechanisms of austempered ductile irons are both micro-cutting and plastic deformation.

  16. Improvements in Microstructure and Wear Resistance of Plasma-Sprayed Fe-Based Amorphous Coating by Laser-Remelting

    NASA Astrophysics Data System (ADS)

    Jiang, Chaoping; Chen, Hong; Wang, Gui; Chen, Yongnan; Xing, Yazhe; Zhang, Chunhua; Dargusch, Matthew

    2017-04-01

    Amorphous coating technology is an attractive way of taking advantage of the superior properties of amorphous alloys for structural applications. However, the limited bonds between splats within the plasma-sprayed coatings result in a typically lamellar and porous coating structure. To overcome these limitations, the as-sprayed coating was treated by a laser-remelting process. The microstructure and phase composition of two coatings were analyzed using scanning electron microscopy with energy-dispersive spectroscopy, transmission electron microscopy, and x-ray diffraction. The wear resistance of the plasma-sprayed coating and laser-remelted coating was studied comparatively using a pin-on-disc wear test under dry friction conditions. It was revealed that the laser-remelted coating exhibited better wear resistance because of its defect-free and amorphous-nanocrystalline composited structure.

  17. Wear Behavior and Mechanism of a Cr-Mo-V Cast Hot-Working Die Steel

    NASA Astrophysics Data System (ADS)

    Wei, M. X.; Wang, S. Q.; Zhao, Y. T.; Chen, K. M.; Cui, X. H.

    2011-06-01

    The wear behavior and mechanisms of a Cr-Mo-V cast hot-working die steel with three microstructures (tempered martensite, troostite, and sorbite) were studied systematically through the dry-sliding wear tests within a normal load range of 50 to 300 N and an ambient temperature range of 298 K to 673 K (25 °C to 400 °C) by a pin-on-disk high-temperature wear machine. Five different mechanisms were observed in the experiments, namely adhesive, abrasive, mild oxidative, oxidative, and extrusive wear; one or more of those mechanisms would be dominant within particular ranges of load and temperature. The transition of wear mechanisms depended on the formation of tribo-oxides, which was related closely to load and temperature, and their delamination, which was mainly influenced by the matrix. By increasing the load and ambient temperature, the protective effect of tribo-oxides first strengthened, then decreased, and in some cases disappeared. Under a load ranging 50 to 300 N at 298 K (25 °C) and a load of 50 N at 473 K (200 °C), adhesive wear was the dominant wear mechanism, and abrasive wear appeared simultaneously. The wear was of mild oxidative type under a load ranging 100 to 300 N at 473 K (200 °C) and a load ranging 50 to 150 N at 673 K (400 °C) for tempered martensite and tempered troostite as well as under a load of 100 N at 473 K (200 °C) and a load ranging 50 to 100 N at 673 K (400 °C) for tempered sorbite. At the load of 200 N or greater, or the temperatures above 673 K (400 °C), oxidative wear (beyond mild oxidative wear) prevailed. When the highest load of 300 N at 673 K (400 °C) was applied, extrusive wear started to dominate for the tempered sorbite.

  18. The fabrication of flip-covered plasmonic nanostructure surfaces with enhanced wear resistance

    NASA Astrophysics Data System (ADS)

    Jung, Joo-Yun; Sung, Sang-Keun; Kim, Kwang-Seop; Cheon, So-Hui; Lee, Jihye; Choi, Jun-Hyuk; Lee, Eungsug

    2017-01-01

    Exposed nanostructure surfaces often suffer from external dynamic wear, particularly when used in human interaction, resulting in surface defects and the degradation of plasmonic resonance properties particularly in terms of transmittance extinction rate and peak-to-valley slope. In this work, a method for the fabrication of flip-covered silver nanostructure-arrayed surfaces is shown to enhance wear resistance. Selectively transferred silver dot and silver webbed-trench exposed reference samples were fabricated by metal nanoimprint, and flip-covered samples were created by flipping and bonding reference samples onto a PET film coated with an adhesive layer. The samples' spectral transmittance was measured before and after a dynamic wear test. Some spectral shift was observed due to the change in refractive index of the surrounding media, but this was not as significant as the effects of the other chosen geometry factors. It was found that dynamic wear had a greater effect on the plasmonic resonance behavior of the exposed samples than in those that had been flip-covered. This suggests that flip-covering may be an effective strategy for the protection of plasmonic resonators against dynamic wear. It is expected that the slight variations in spectral transmittance could be compensated through proper tuning of the sample geometry.

  19. Wear resistance of thick diamond like carbon coatings against polymeric materials used in single screw plasticizing technology

    NASA Astrophysics Data System (ADS)

    Zitzenbacher, G.; Liu, K.; Forsich, C.; Heim, D.

    2015-05-01

    Wear on the screw and barrel surface accompany polymer single screw plasticizing technology from the beginning. In general, wear on screws can be reduced by using nitrided steel surfaces, fused armour alloys on the screw flights and coatings. However, DLC-coatings (Diamond Like Carbon) comprise a number of interesting properties such as a high hardness, a low coefficient of friction and an excellent corrosion resistance due to their amorphous structure. The wear resistance of about 50 µm thick DLC-coatings against polyamide 6.6, polybutylene terephthalate and polypropylene is investigated in this paper. The tribology in the solids conveying zone of a single screw extruder until the beginning of melting is evaluated using a pin on disc tribometer and a so called screw tribometer. The polymeric pins are pressed against coated metal samples using the pin on disc tribometer and the tests are carried out at a defined normal force and sliding velocity. The screw tribometer is used to perform tribological experiments between polymer pellets and rotating coated metal shafts simulating the extruder screw. Long term experiments were performed to evaluate the wear resistance of the DLC-coating. A reduction of the coefficient of friction can be observed after a frictional distance of about 20 kilometers using glass fibre reinforced polymeric materials. This reduction is independent on the polymer and accompanied by a black layer on the wear surface of the polymeric pins. The DLC-coated metal samples show an up to 16 µm deep wear track after the 100 kilometer test period against the glass fiber filled materials only.

  20. Numerical modelling of tool wear in turning with cemented carbide cutting tools

    NASA Astrophysics Data System (ADS)

    Franco, P.; Estrems, M.; Faura, F.

    2007-04-01

    A numerical model is proposed for analysing the flank and crater wear resulting from the loss of material on cutting tool surface in turning processes due to wear mechanisms of adhesion, abrasion and fracture. By means of this model, the material loss along cutting tool surface can be analysed, and the worn surface shape during the workpiece machining can be determined. The proposed model analyses the gradual degradation of cutting tool during turning operation, and tool wear can be estimated as a function of cutting time. Wear-land width (VB) and crater depth (KT) can be obtained for description of material loss on cutting tool surface, and the effects of the distinct wear mechanisms on surface shape can be studied. The parameters required for the tool wear model are obtained from bibliography and experimental observation for AISI 4340 steel turning with WC-Co cutting tools.

  1. Research on microstructure and wear resistance of coatings obtained by adding nanoparticles of refractory compounds in laser cladding

    NASA Astrophysics Data System (ADS)

    Murzakov, M. A.; Chirikov, S. N.; Markushov, Y. V.

    2016-09-01

    The paper is aimed at research of coatings, which are achieved by means of laser cladding with additives of nanoparticles of high-melting compounds in form of tungsten carbide and tantalum (WC and TaC). In the course of experiment, various ceramic powder concentrations were tested. Main technological characteristics were determined. Power density amounted to 0.68-0.98 MW/cm2. During the coating wear resistance measurement, it was discovered that increase in nanopowder concentration extended wear resistance of coating 2-6 times. Wear resistance measurement and wear coefficient calculation were performed using Brinell-Howarth method. The load was 15 N, load time was 10 minutes. Optical metallographic microscope Neophot-30 was used to study microstructure of the deposited coatings. To reveal microstructure of the deposited coatings, the samples were exposed to chemical etching. Elemental composition of the samples was determined by the methods of X- ray microanalysis in testing solution using electron microscope EVO-50 under acceleration voltage 10-20 kV (probe current 5-50 nA) using energy- and wavelength-dispersive spectrometers.

  2. Scratching technique for the study and analysis of soil surface abrasion mechanism

    NASA Astrophysics Data System (ADS)

    Ta, Wanquan

    2007-11-01

    Aeolian abrasion is the most fundamental and active surface process that takes place in arid and semi-arid environments. Its nature is a wear process for wind blown grains impinging on a soil or sediment surface, which causes particles and aggregates to fracture from the soil surface through a series of plastic and brittle cracking deformation such as cutting, ploughing and brittle fracturing. Using a Universal Micro-Tribometer (UMT), a scratching test was carried out on six soil surfaces (sandy soil, sand loam, silt loam, loam, silt clay loam, and silt clay). The results indicate that traces of normal and tangential force vs. time show a jagged curve, which can reflect the plastic deformation and brittle fracturing of aggregates and particles of various sizes fractured from the soil surfaces. The jagged curve peaks, and the area enclosed underneath, may represent the bonding forces and bonding energies of some aggregates and grains on the soil surface, respectively. Connecting the scratching test with an impact abrasion experiment furthermore demonstrates that soil surface abrasion rates are proportional to the square of speeds of impacting particles and to the 2.6 power of mean soil grain size, and inversely proportional to the 1.5 power of specific surface abrasive energy or to the 1.7 power of specific surface hardness.

  3. Optimization of Profile and Material of Abrasive Water Jet Nozzle

    NASA Astrophysics Data System (ADS)

    Anand Bala Selwin, K. P.; Ramachandran, S.

    2017-05-01

    The objective of this work is to study the behaviour of the abrasive water jet nozzle with different profiles and materials. Taguchi-Grey relational analysis optimization technique is used to optimize the value with different material and different profiles. Initially the 3D models of the nozzle are modelled with different profiles by changing the tapered inlet angle of the nozzle. The different profile models are analysed with different materials and the results are optimized. The optimized results would give the better result taking wear and machining behaviour of the nozzle.

  4. Wear Properties of ECAP-Processed AM80 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Gopi, K. R.; Shivananda Nayaka, H.; Sahu, Sandeep

    2017-07-01

    AM80 magnesium alloy was subjected to equal-channel angular pressing (ECAP), and microstructural evolution was studied using scanning electron microscope (SEM). Grain size was found to decrease up to 3 µm after four passes. An increase in number of ECAP passes led to a corresponding increase in hardness of the processed samples. Unprocessed and ECAP-processed samples were subjected to wear test using pin-on-disk wear test machine to study the wear behavior. Effects of varying loads (30 and 40 N) with sliding distances (2500 and 5000 m) were studied. The results showed reduction in wear mass loss for the ECAP-processed samples in comparison with unprocessed condition. Coefficient of friction (COF) was studied for different loads, and improvement in COF values was observed for ECAP-processed samples compared to unprocessed condition. Worn surfaces were studied using SEM and energy-dispersive x-ray spectrometer, and they exhibited plastic deformation, delamination, plowing, wear debris and oxidation in the sliding direction. X-ray diffraction analysis was conducted on the worn surfaces to identify the phases. It revealed the presence of magnesium oxide and magnesium aluminum oxide which led to oxidation wear in the sliding direction. Wear mechanism was found to be abrasive and oxidation wear.

  5. Transparent, superhydrophobic, and wear-resistant surfaces using deep reactive ion etching on PDMS substrates.

    PubMed

    Ebert, Daniel; Bhushan, Bharat

    2016-11-01

    Surfaces that simultaneously exhibit superhydrophobicity, low contact angle hysteresis, and high transmission of visible light are of interest for many applications, such as optical devices, solar panels, and self-cleaning windows. Superhydrophobicity could also find use in medical devices where antifouling characteristics are desirable. These applications also typically require mechanical wear resistance. The fabrication of such surfaces is challenging due to the competing goals of superhydrophobicity and transmittance in terms of the required degree of surface roughness. In this study, deep reactive ion etching (DRIE) was used to create rough surfaces on PDMS substrates using a O2/CF4 plasma. Surfaces then underwent an additional treatment with either octafluorocyclobutane (C4F8) plasma or vapor deposition of perfluorooctyltrichlorosilane (PFOTCS) following surface activation with O2 plasma. The effects of surface roughness and the additional surface modifications were examined with respect to the contact angle, contact angle hysteresis, and optical transmittance. To examine wear resistance, a sliding wear experiment was performed using an atomic force microscope (AFM). Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Wear-resistant ball bearings for space applications. [coated with titanium carbide

    NASA Technical Reports Server (NTRS)

    Boving, H.; Hintermann, H. E.; Haenni, W.; Bondivenne, E.; Boeto, M.; Conde, M.

    1977-01-01

    Ball bearings for hostile environments were developed. They consist of normal ball bearing steel parts of which the rings are coated with hard, wear-resistant, chemical vapor deposited (C.V.D) TiC. Experiments in ultrahigh vacuum, using cages of various materials with self-lubricating properties, have shown that such bearings are suitable for space applications.

  7. A WEAR MODEL FOR DIESEL ENGINE EXHAUST VALVES

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Blau, Peter Julian

    2009-11-01

    seats run for hundreds of hours in heavy-duty diesels provided insights into the kinds of complexity that the contact conditions in engines can produce, and suggested the physical basis for the current approach to modeling. The model presented here involves four terms, two representing the valve response and two for its mating seat material. The model's structure assumes that wear that takes place under a complex combination of plastic deformation, tangential shear, and oxidation. Tribolayers form, are removed, and may reform. Layer formation affects the friction forces in the interface, and in turn, the energy available to do work on the materials to cause wear. To provide friction data for the model at various temperatures, sliding contact experiments were conducted from 22 to 850 C in a pin-on-disk apparatus at ORNL. In order to account for the behavior of different materials and engine designs, parameters in all four terms of the model can be adjusted to account for wear-in and incubation periods before the dominant wear processes evolve to their steady-state rates. For example, the deformation rate is assumed to be maximum during the early stages of operation, and then, due to material work-hardening and the increase in nominal contact area (which reduces the load per unit area), decreases to a lower rate at long times. Conversely, the rate of abrasion increases with time or number of cycles due to the build-up of oxides and tribo-layers between contact surfaces. The competition between deformation and abrasion results in complex, non-linear behavior of material loss per cycle of operation. Furthermore, these factors are affected by valve design features, such as the angle of incline of the valve seat. Several modeling scenarios are presented to demonstrate how the wear profile versus number of cycles changes in response to: (a) different relative abrasion rates of the seat and valve materials, (b) the friction coefficient as a function of temperature, (c) the

  8. Titanium aluminide intermetallic alloys with improved wear resistance

    DOEpatents

    Qu, Jun; Lin, Hua-Tay; Blau, Peter J.; Sikka, Vinod K.

    2014-07-08

    The invention is directed to a method for producing a titanium aluminide intermetallic alloy composition having an improved wear resistance, the method comprising heating a titanium aluminide intermetallic alloy material in an oxygen-containing environment at a temperature and for a time sufficient to produce a top oxide layer and underlying oxygen-diffused layer, followed by removal of the top oxide layer such that the oxygen-diffused layer is exposed. The invention is also directed to the resulting oxygen-diffused titanium aluminide intermetallic alloy, as well as mechanical components or devices containing the improved alloy composition.

  9. Morphology and Performance of 5Cr5MoV Casting Die Steel in the Process of Surfacing

    NASA Astrophysics Data System (ADS)

    Song, Yulai; Kong, Xiangrui; Yang, Pengcong; Fu, Hongde; Wang, Xuezhu

    2017-12-01

    To investigate the microstructures and mechanical properties of the deposited metal on surface of die steel, two layer of weld-seam were prepared on the surface of 5Cr5MoV die steel by arc surfacing. The surface microstructures and microhardness were characterized by scanning electron microscopy, energy dispersive spectrometer and Vickers microhardness tester, respectively. The effect of load on the abrasion resistance and wear mechanism of the base metal and surfacing metal was studied by pin-on-disk tribometer. The results showed that martensite and retained austenite exist in weld-seam, both of them grow up in the form of dendrites and equiaxed grains and microhardness reach 774.2HV. The microstructures of the quenching zone mainly consist of martensite and retained austenite, while tempered martensite is the dominant phase in partial quenching zone. The abrasion resistance of the surfacing metal is superior to the base metal based on the results of wear test. The wear rates of surfacing metal and base metal raise with the increase of load. The wear rates of base metal raise extremely when the load reach 210N. Both of two kinds of materials have the similar wear mechanism, namely, abrasive wear at low load, oxidative wear and adhesive wear at high load.

  10. Simplified Abrasion Test Methodology for Candidate EVA Glove Lay-Ups

    NASA Technical Reports Server (NTRS)

    Rabel, Emily; Aitchison, Lindsay

    2015-01-01

    During the Apollo Program, space suit outer-layer fabrics were badly abraded after performing just a few extravehicular activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots that penetrated the outer-layer fabric into the thermal protection layers after less than 8 hrs of surface operations. Current plans for the exploration planetary space suits require the space suits to support hundreds of hours of EVA on a lunar or Martian surface, creating a challenge for space suit designers to utilize materials advances made over the last 40 years and improve on the space suit fabrics used in the Apollo Program. Over the past 25 years the NASA Johnson Space Center Crew and Thermal Systems Division has focused on tumble testing as means of simulating wear on the outer layer of the space suit fabric. Most recently, in 2009, testing was performed on 4 different candidate outer layers to gather baseline data for future use in design of planetary space suit outer layers. In support of the High Performance EVA Glove Element of the Next Generation Life Support Project, testing a new configuration was recently attempted in which require 10% of the fabric per replicate of that need in 2009. The smaller fabric samples allowed for reduced per sample cost and flexibility to test small samples from manufacturers without the overhead to have a production run completed. Data collected from this iteration was compared to that taken in 2009 to validate the new test method. In addition the method also evaluated the fabrics and fabric layups used in a prototype thermal micrometeoroid garment (TMG) developed for EVA gloves under the NASA High Performance EVA Glove Project. This paper provides a review of previous abrasion studies on space suit fabrics, details methodologies used for abrasion testing in this particular study, results of the validation study, and results of the TMG testing.

  11. An evaluation of wear when enamel is opposed by various ceramic materials and gold.

    PubMed

    Elmaria, Asmaa; Goldstein, Gary; Vijayaraghavan, Therizhandur; Legeros, Raquel Z; Hittelman, Eugene L

    2006-11-01

    Ceramic restorations have been known to cause wear of opposing enamel. The purpose of this study was to evaluate enamel wear caused by 3 ceramic substrates in the glazed and polished conditions. Sixty ceramic discs (10 x 2 mm)-20 each of Finesse, All-Ceram, and IPS-Empress-were prepared and glazed. Each group of 20 was divided into 2 groups of 10. The surfaces of one group were ground and polished using a porcelain polishing kit (Dialite). The remaining 10 were left as glazed. Ten specimens of a type III gold alloy were cast into rectangular shapes of 10 x 12 x 2 mm and polished. Seventy human cusps were prepared from sound, caries-free, extracted teeth and abraded against the substrates in a wear machine for a total of 10,000 cycles. The cusp height loss was traced before and after the wear test using a profile projector. Mean surface roughness (R(a)) values for the substrates were also recorded with a profilometer before testing. Differences in R(a) were evaluated using 1- and 2-way ANOVA and the Scheffe post hoc test (alpha = .05). One-way ANOVA indicated that enamel height loss was significantly different by material (P < .001) and surface condition (glazed and polished or glazed; P < .05). Gold, polished Finesse, and polished All-Ceram were the least abrasive, whereas glazed IPS-Empress was the most abrasive. There was no significant interaction effect between substrate type and surface condition. Significant differences were found when R(a) of the substrate condition was compared with enamel wear (P < .01). Gold, polished Finesse, and polished All-Ceram caused the least enamel wear, whereas IPS-Empress caused the most wear. Cast gold was significantly different than glazed IPS-Empress (P < .05), whereas other groups overlapped. There was significant correlation between R(a) and enamel wear (P < .01).

  12. Friction and wear behaviors of MoS2/Zr coated HSS in sliding wear and in drilling processes

    NASA Astrophysics Data System (ADS)

    Deng, Jianxin; Yan, Pei; Wu, Ze

    2012-11-01

    MoS2 metal composite coatings have been successful used in dry turning, but its suitability for dry drilling has not been yet established. Therefore, it is necessary to study the friction and wear behaviors of MoS2/Zr coated HSS in sliding wear and in drilling processes. In the present study, MoS2/Zr composite coatings are deposited on the surface of W6Mo5Cr4V2 high speed steel(HSS). Microstructural and fundamental properties of these coatings are examined. Ball-on-disc sliding wear tests on the coated discs are carried out, and the drilling performance of the coated drills is tested. Test results show that the MoS2/Zr composite coatings exhibit decreases friction coefficient to that of the uncoated HSS in sliding wear tests. Energy dispersive X-ray(EDX) analysis on the wear surface indicates that there is a transfer layer formed on the counterpart ball during sliding wear processes, which contributes to the decreasing of the friction coefficient between the sliding couple. Drilling tests indicate that the MoS2/Zr coated drills show better cutting performance compared to the uncoated HSS drills, coating delamination and abrasive are found to be the main flank and rake wear mode of the coated drills. The proposed research founds the base of the application of MoS2 metal composite coatings on dry drilling.

  13. Self-healing Characteristics of Collagen Coatings with Respect to Surface Abrasion

    PubMed Central

    Kim, Chang-Lae; Kim, Dae-Eun

    2016-01-01

    A coating based on collagen with self-healing properties was developed for applications in mechanical components that are prone to abrasion due to contact with a counter surface. The inherent swelling behavior of collagen in water was exploited as the fundamental mechanism behind self-healing of a wear scar formed on the surface. The effects of freeze-drying process and water treatment of the collagen coatings on their mechanical and self-healing properties were analyzed. Water was also used as the medium to trigger the self-healing effect of the collagen coatings after the wear test. It was found that collagen coatings without freeze-drying did not demonstrate any self-healing effect whereas the coatings treated by freeze-drying process showed remarkable self-healing effect. Overall, collagen coatings that were freeze-dried and water treated showed the best friction and self-healing properties. Repeated self-healing ability of these coatings with respect to wear scar was also demonstrated. It was also confirmed that the self-healing property of the collagen coating was effective over a relatively wide range of temperature. PMID:27010967

  14. Self-healing Characteristics of Collagen Coatings with Respect to Surface Abrasion

    NASA Astrophysics Data System (ADS)

    Kim, Chang-Lae; Kim, Dae-Eun

    2016-03-01

    A coating based on collagen with self-healing properties was developed for applications in mechanical components that are prone to abrasion due to contact with a counter surface. The inherent swelling behavior of collagen in water was exploited as the fundamental mechanism behind self-healing of a wear scar formed on the surface. The effects of freeze-drying process and water treatment of the collagen coatings on their mechanical and self-healing properties were analyzed. Water was also used as the medium to trigger the self-healing effect of the collagen coatings after the wear test. It was found that collagen coatings without freeze-drying did not demonstrate any self-healing effect whereas the coatings treated by freeze-drying process showed remarkable self-healing effect. Overall, collagen coatings that were freeze-dried and water treated showed the best friction and self-healing properties. Repeated self-healing ability of these coatings with respect to wear scar was also demonstrated. It was also confirmed that the self-healing property of the collagen coating was effective over a relatively wide range of temperature.

  15. Carbon-Based Wear Coatings: Properties and Applications

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    2003-01-01

    The technical function of numerous engineering systems - such as vehicles, machines, and instruments - depends on the processes of motion and on the surface systems. Many processes in nature and technology depend on the motion and dynamic behavior of solids, liquids, and gases. Smart surface systems are essential because of the recent technological push toward higher speeds, loads, and operating temperatures; longer life; lighter weight and smaller size (including nanotechnology); and harsh environments in mechanical, mechatronic, and biomechanical systems. If proper attention is not given to surface systems, then vehicles, machines, instruments, and other technical systems could have short lives, consume excessive energy, experience breakdowns, result in liabilities, and fail to accomplish their missions. Surface systems strongly affect our national economy and our lifestyles. At the NASA Glenn Research Center, we believe that proper attention to surface systems, especially in education, research, and application, could lead to economic savings of between 1.3 and 1.6 percent of the gross domestic product. Wear coatings and surface systems continue to experience rapid growth as new coating and surface engineering technologies are discovered, more cost-effective coating and surface engineering solutions are developed, and marketers aggressively pursue, uncover, and exploit new applications for engineered surface systems in cutting tools and wear components. Wear coatings and smart surface systems have been used widely in industrial, consumer, automotive, aerospace, and biomedical applications. This presentation expresses the author's views of and insights into smart surface systems in wear coatings. A revolution is taking place in carbon science and technology. Diamond, an allotrope of carbon, joins graphite, fullerenes, and nanotubes as its major pure carbon structures. It has a unique combination of extreme properties: hardness and abrasion resistance; adhesion

  16. Fretting Wear of Ti-48Al-2Cr-2Nb

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Lerch, Bradley A.; Draper, Susan L.

    2001-01-01

    An investigation was conducted to examine the wear behavior of gamma titanium aluminide (Ti-48Al-2Cr-2Nb in atomic percent) in contact with a typical nickel-base superalloy under repeated microscopic vibratory motion in air at temperatures from 296-823 K. The surface damage observed on the interacting surfaces of both Ti-48Al-2Cr-2Nb and superalloy consisted of fracture pits, oxides, metallic debris, scratches, craters, plastic deformation, and cracks. The Ti-48Al-2Cr-2Nb transferred to the superalloy at all fretting conditions and caused scuffing or galling. The increasing rate of oxidation at elevated temperatures led to a drop in Ti-48Al-2Cr-2Nb wear at 473 K. Mild oxidative wear was observed at 473 K. However, fretting wear increased as the temperature was increased from 473-823 K. At 723 and 823 K, oxide disruption generated cracks, loose wear debris, and pits on the Ti-48Al-2Cr-2Nb wear surface. Ti-48Al-2Cr-2Nb wear generally decreased with increasing fretting frequency. Both increasing slip amplitude and increasing load tended to produce more metallic wear debris, causing severe abrasive wear in the contacting metals. Keywords

  17. Selected fretting-wear-resistant coatings for titanium - 6-percent-aluminum - 4-percent-vanadium alloy

    NASA Technical Reports Server (NTRS)

    Bill, R. C.

    1976-01-01

    A titanium - 6-percent-aluminum - 4-percent-vanadium alloy (Ti-6Al-4V) was subjected to fretting-wear exposures against uncoated Ti-6Al-4V as a baseline and against various coatings and surface treatments applied to Ti-6Al-4V. The coatings evaluated included plasma-sprayed tungsten carbide with 12 percent cobalt, aluminum oxide with 13 percent titanium oxide, chromium oxide, and aluminum bronze with 10 percent aromatic polyester; polymer-bonded polyimide, polyimide with graphite fluoride, polyimide with molybdenum disulfide (MoS2), and methyl phenyl silicone bonded MoS2, preoxidation surface treatment, a nitride surface treatment, and a sputtered MoS2 coating. Results of wear measurements on both the coated and uncoated surfaces after 300,000 fretting cycles indicated that the polyimide coating was the most wear resistant and caused the least wear to the uncoated mating surface.

  18. Toothbrushing after an erosive attack: will waiting avoid tooth wear?

    PubMed

    Lussi, Adrian; Lussi, Jonas; Carvalho, Thiago S; Cvikl, Barbara

    2014-10-01

    The purpose of this study was to determine if storage for up to 4 h in human saliva results in a decrease of erosive tooth wear (ETW) and in an increase of surface microhardness (SMH) of enamel samples after an erosive attack with subsequent abrasion. Furthermore, we determined the impact of individual salivary parameters on ETW and SMH. Enamel samples were distributed into five groups: group 1 had neither erosion nor saliva treatment; groups 2-5 were treated with erosion, then group 2 was placed in a humid chamber and groups 3-5 were incubated in saliva for 30 min, 2 h, and 4 h, respectively. After erosion and saliva treatments, all groups were treated with abrasion. Surface microhardness and ETW were measured before and after erosion, incubation in saliva, and abrasion. Surface microhardness and ETW showed significant changes throughout the experiment: SMH decreased and ETW increased in groups 2-5, regardless of the length of incubation in saliva. The results of groups 3-5 (exposed to saliva) were not significantly different from those of group 2 (not exposed to saliva). Exposure of eroded enamel to saliva for up to 4 h was not able to increase SMH or reduce ETW. However, additional experiments with artificial saliva without proteins showed protection from erosive tooth wear. The recommendation to postpone toothbrushing of enamel after an erosive attack should be reconsidered. © 2014 Eur J Oral Sci.

  19. In Vitro Assessment of the Abrasion Resistance of Two Types of Artificial Teeth Submitted to Brushing.

    PubMed

    Policastro, Vivian Barnabé; Giro, Gabriela; Leite, Andressa Rosa Perin; Mendoza-Marin, Danny Omar; Paleari, André Gustavo; Compagnoni, Marco Antonio; Pero, Ana Carolina

    2016-08-01

    To assess the effect of brushing with different solutions on the abrasion resistance of two types of acrylic resin teeth. Maxillary premolars from two types of acrylic teeth (Biotone and Biotone IPN) were divided into six groups (n = 12), according to the solution used during brushing: distilled water (control), coconut soap, or dentifrice. A mechanical brushing machine was used to simulate approximately 1 year of brushing (11,000 strokes). The weight loss (WL) of teeth was obtained from the difference between the initial (IW) and final weight (FW) of each specimen, and the mean of percentage of weight loss (PWL) was calculated for each group. Data were analyzed using the Kruskal-Wallis test, followed by Bonferroni's post-test comparison (α = 0.05). A statistically significant difference was found for the factor solution (p < 0.001). Brushing using dentifrice caused the highest values of weight loss (-0.50%), in comparison with the groups brushed with coconut soap (0.00%) or distilled water (0.00%). For both types of artificial teeth, brushing with dentifrice produced higher abrasion than brushing with coconut soap or water. © 2016 by the American College of Prosthodontists.

  20. Erosion and abrasion-inhibiting in situ effect of the Euclea natalensis plant of African regions.

    PubMed

    Sales-Peres, Silvia Helena de Carvalho; Xavier, Cheila Nilza Hamina; Mapengo, Marta Artemisa Abel; Forim, Moacir Rossi; Silva, Maria de Fatima; Sales-Peres, Arsenio

    2016-06-14

    This study evaluated the effect of Euclea natalensis gel on the reduction of erosive wear with or without abrasion, in enamel and dentin. During two five-day experimental crossover phases, volunteers (n = 10) wore palatal devices containing human enamel and dentin blocks (E = 8 and D = 8). The gel was applied in a thin layer in the experimental group, and was not applied in the control group. In the intraoral phase, volunteers used the palatal appliance for 12 h before the gel treatment, and were instructed to start the erosive challenges 6 h after the gel application. Erosion was performed with Coca-Cola® (for 5 min) 4 times/day. The appliance was then put back into the mouth and was brushed after 30 minutes. After intraoral exposure, the appliances were removed and the specimens were analyzed using profilometry (mean ± SD, μm). The Euclea natalensis gel caused less wear in enamel in the experimental group (EROS = 12.86 ± 1.75 µm; EROS + ABRAS = 12.13 ± 2.12 µm) than in the control group (EROS = 14.12 ± 7.66 µm; EROS + ABRAS = 16.29 ± 10.72 µm); however, the groups did not differ from each other significantly. A statistically significant value was found for erosion and eros + abrasion in dentin (p = 0.001). Euclea natalensis may play a role in the prevention of dentin loss under mild erosive and abrasive conditions. A clinical trial is required to confirm these promising results in a clinical situation.

  1. Modeling of Micro Deval abrasion loss based on some rock properties

    NASA Astrophysics Data System (ADS)

    Capik, Mehmet; Yilmaz, Ali Osman

    2017-10-01

    Aggregate is one of the most widely used construction material. The quality of the aggregate is determined using some testing methods. Among these methods, the Micro Deval Abrasion Loss (MDAL) test is commonly used for the determination of the quality and the abrasion resistance of aggregate. The main objective of this study is to develop models for the prediction of MDAL from rock properties, including uniaxial compressive strength, Brazilian tensile strength, point load index, Schmidt rebound hardness, apparent porosity, void ratio Cerchar abrasivity index and Bohme abrasion test are examined. Additionally, the MDAL is modeled using simple regression analysis and multiple linear regression analysis based on the rock properties. The study shows that the MDAL decreases with the increase of uniaxial compressive strength, Brazilian tensile strength, point load index, Schmidt rebound hardness and Cerchar abrasivity index. It is also concluded that the MDAL increases with the increase of apparent porosity, void ratio and Bohme abrasion test. The modeling results show that the models based on Bohme abrasion test and L type Schmidt rebound hardness give the better forecasting performances for the MDAL. More models, including the uniaxial compressive strength, the apparent porosity and Cerchar abrasivity index, are developed for the rapid estimation of the MDAL of the rocks. The developed models were verified by statistical tests. Additionally, it can be stated that the proposed models can be used as a forecasting for aggregate quality.

  2. Al2O3-TiC Composite Prepared by Spark Plasma Sintering Process: Evaluation of Mechanical and Tribological Properties

    NASA Astrophysics Data System (ADS)

    Kumar, Rohit; Chaubey, A. K.; Bathula, Sivaiah; Prashanth, K. G.; Dhar, Ajay

    2018-03-01

    Al2O3-10TiC composites were synthesized by spark plasma sintering (SPS) process. Microstructural and mechanical properties of the composite reveal homogeneous distribution of the fine TiC particles in the matrix. The samples were produced with different sintering temperature, and it shows that the hardness and density gradually increases with increasing sintering temperature. Abrasion wear test result reveals that the composite sintered at 1500 °C shows high abrasion resistance (wt. loss 0.016 g) and the lowest abrasion resistance was observed for the composite sample sintered at 1100 °C (wt. loss 1.459 g). The profilometry surface roughness study shows that sample sintered at 1100 °C shows maximum roughness ( R a = 6.53 µm) compared to the sample sintered at 1500 °C ( R a = 0.66 µm) corroborating the abrasion wear test results.

  3. Physico-mechanical and wear properties of novel sustainable sour-weed fiber reinforced polyester composites

    NASA Astrophysics Data System (ADS)

    Patel, Vinay Kumar; Chauhan, Shivani; Katiyar, Jitendra Kumar

    2018-04-01

    In this study, a novel natural fiber i.e. Sour-weed botanically known as ‘Rumex acetosella’ has been first time introduced as natural reinforcements to polyester matrix. The natural fiber based polyester composites were fabricated by hand lay-up technique using different sizes and different weight percentages. In Sour-weed/Polyester composites, physical (density, water absorption and hardness), mechanical properties (tensile and impact properties) and wear properties (sand abrasion and sliding wear) were investigated for different sizes of sour weed of 0.6 mm, 5 mm, 10 mm, 15 mm and 20 mm at 3, 6 and 9 weight percent loading, respectively in polyester matrix. Furthermore, on average value of results, the multi-criteria optimization technique i.e. TOPSIS was employed to decide the ranking of the composites. From the optimized results, it was observed that Sour-weed composite reinforced with fiber’s size of 15 mm at 6 wt% loading demonstrated the best ranked composite exhibiting best overall properties as average tensile strength of 34.33 MPa, average impact strength of 10 Joule, average hardness of 12 Hv, average specific sand abrasion wear rate of 0.0607 mm3 N‑1m‑1, average specific sliding wear rate of 0.002 90 mm3 N‑1m‑1, average percentage of water absorption of 3.446% and average density of 1.013 among all fabricated composites.

  4. Tooth wear: the view of the anthropologist

    PubMed Central

    2007-01-01

    Anthropologists have for many years considered human tooth wear a normal physiological phenomenon where teeth, although worn, remain functional throughout life. Wear was considered pathological only if pulpal exposure or premature tooth loss occurred. In addition, adaptive changes to the stomatognathic system in response to wear have been reported including continual eruption, the widening of the masticatory cycle, remodelling of the temporomandibular joint and the shortening of the dental arches from tooth migration. Comparative studies of many different species have also documented these physiological processes supporting the idea of perpetual change over time. In particular, differential wear between enamel and dentine was considered a physiological process relating to the evolution of the form and function of teeth. Although evidence of attrition and abrasion has been known to exist among hunter-gatherer populations for many thousands of years, the prevalence of erosion in such early populations seems insignificant. In particular, non-carious cervical lesions to date have not been observed within these populations and therefore should be viewed as ‘modern-day’ pathology. Extrapolating this anthropological perspective to the clinical setting has merits, particularly in the prevention of pre-mature unnecessary treatment. PMID:17938977

  5. Tooth wear: the view of the anthropologist.

    PubMed

    Kaidonis, John A

    2008-03-01

    Anthropologists have for many years considered human tooth wear a normal physiological phenomenon where teeth, although worn, remain functional throughout life. Wear was considered pathological only if pulpal exposure or premature tooth loss occurred. In addition, adaptive changes to the stomatognathic system in response to wear have been reported including continual eruption, the widening of the masticatory cycle, remodelling of the temporomandibular joint and the shortening of the dental arches from tooth migration. Comparative studies of many different species have also documented these physiological processes supporting the idea of perpetual change over time. In particular, differential wear between enamel and dentine was considered a physiological process relating to the evolution of the form and function of teeth. Although evidence of attrition and abrasion has been known to exist among hunter-gatherer populations for many thousands of years, the prevalence of erosion in such early populations seems insignificant. In particular, non-carious cervical lesions to date have not been observed within these populations and therefore should be viewed as 'modern-day' pathology. Extrapolating this anthropological perspective to the clinical setting has merits, particularly in the prevention of pre-mature unnecessary treatment.

  6. The optimization study on the tool wear of carbide cutting tool during milling Carbon Fibre Reinforced (CFRP) using Response Surface Methodology (RSM)

    NASA Astrophysics Data System (ADS)

    Nor Khairusshima, M. K.; Hafiz Zakwan, B. Muhammad; Suhaily, M.; Sharifah, I. S. S.; Shaffiar, N. M.; Rashid, M. A. N.

    2018-01-01

    Carbon Fibre Reinforced Plastic (CFRP) composite has become one of famous materials in industry, such as automotive, aeronautics, aerospace and aircraft. CFRP is attractive due to its properties, which promising better strength and high specification of mechanical properties other than its high resistance to corrosion. Other than being abrasive material due to the carbon nature, CFRP is an anisotropic material, which the knowledge of machining metal and steel cannot be applied during machining CFRP. The improper technique and parameters used to machine CFRP may result in high tool wear. This paper is to study the tool wear of 8 mm diameter carbide cutting tool during milling CFRP. To predict the suitable cutting parameters within range of 3500-6220 (rev/min), 200-245 (mm/min), and 0.4-1.8 (mm) for cutting speed, speed, feed rate and depth of cut respectively, which produce optimized result (less tool wear), Response Surface Methodology (RSM) has been used. Based on the developed mathematical model, feed rate was identified as the primary significant item that influenced tool wear. The optimized cutting parameters are cutting speed, feed and depth of cut of 3500 rev/min, 200 mm/min and 0.5 mm, respectively, with tool wear of 0.0267 mm. It is also can be observed that as the cutting speed and feed rate increased the tool wear is increasing.

  7. Experience with wear-resistant materials at the Homer City Coal Cleaning Plant

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Williams, W.R.

    1984-10-01

    The Homer City preparation plant is a multi-stream, dual-circuit facility with a capacity of 1200 ton/hour raw feed. It serves 3 units of a neighbouring power station. Experience with a number of wear and corrosion resistant materials is described. It is emphasised that the successes and failures reported may be site-specific.

  8. Electron Microscopy Abrasion Analysis of Candidate Fabrics for Planetary Space Suit Protective Overgarment Application

    NASA Technical Reports Server (NTRS)

    Hennessy, Mary J.

    1992-01-01

    The Electron Microscopy Abrasion Analysis of Candidate Fabrics for Planetary Space Suit Protective Overgarment Application is in support of the Abrasion Resistance Materials Screening Test. The fundamental assumption made for the SEM abrasion analysis was that woven fabrics to be used as the outermost layer of the protective overgarment in the design of the future, planetary space suits perform best when new. It is the goal of this study to determine which of the candidate fabrics was abraded the least in the tumble test. The sample that was abraded the least will be identified at the end of the report as the primary candidate fabric for further investigation. In addition, this analysis will determine if the abrasion seen by the laboratory tumbled samples is representative of actual EVA Apollo abrasion.

  9. On the influence of Ti-Al intermetallic coating architecture on mechanical properties and wear resistance of end mills

    NASA Astrophysics Data System (ADS)

    Vardanyan, E. L.; Budilov, V. V.; Ramazanov, K. N.; Ataullin, Z. R.

    2017-07-01

    Thin-film wear-resistant coatings are widely used to increase life and efficiency of metal cutting tools. This paper shows the results of a study on the influence of architecture (number, sequence and thickness of layers) of wear-resistant coatings on physical, mechanical and operational properties of end mills. Coatings consisting of alternating Ti-Al/Ti-Al-N layers of equal thickness demonstrated the best physical and mechanical properties. Durability of coated tools when processing materials from chromium-vanadium steel increased twice as compared to uncoated tools.

  10. Wear and friction behavior of Al-TiB2-nano-Gr hybrid composites fabricated through ultrasonic cavitation assisted stir casting

    NASA Astrophysics Data System (ADS)

    Poria, Suswagata; Sutradhar, Goutam; Sahoo, Prasanta

    2018-05-01

    The present study reports the role of nano-graphite particles in determining wear and friction behavior of Al-TiB2-nano-Gr hybrid composites. Ultrasonic cavitation assisted stir casting method has been used for fabrication of composites. Al-Si5Cu3 alloy is used as base alloy along with micro sized TiB2 hard ceramic particles (2.5 and 5.5 wt%) as reinforcement and nano-Gr particles (2 and 4 wt%) as solid lubricant additives. SEM micrographs, EDAX spectrum and optical images are considered to observe uniform dispersion of reinforcing phases. Micro-hardness is evaluated using Vicker’s microhardness tester. Hardness is seen to increase with incorporation of TiB2 while the same decreases with incorporation of graphite. Wear and friction of composites are tested for varying load (10 to 40 N) and sliding speed (0.2 to 0.4 m s‑1) using a pin-on-disk tribometer. Worn surfaces are characterized using SEM and EDAX analysis. Wear resistance of composites increases with incorporation of reinforcing phases together. Nano-Gr particles are easily sheared out from the sub-surface and provide a layer over the tribo-surface of composite that enhances friction and wear behavior. Wear mechanism in composites is predominantly adhesion while abrasion and ploughing is prominent in base alloy.

  11. A high-strength silicide phase in a stainless steel alloy designed for wear-resistant applications.

    PubMed

    Bowden, D; Krysiak, Y; Palatinus, L; Tsivoulas, D; Plana-Ruiz, S; Sarakinou, E; Kolb, U; Stewart, D; Preuss, M

    2018-04-10

    Hardfacing alloys provide strong, wear-resistant and corrosion-resistant coatings for extreme environments such as those within nuclear reactors. Here, we report an ultra-high-strength Fe-Cr-Ni silicide phase, named π-ferrosilicide, within a hardfacing Fe-based alloy. Electron diffraction tomography has allowed the determination of the atomic structure of this phase. Nanohardness testing indicates that the π-ferrosilicide phase is up to 2.5 times harder than the surrounding austenite and ferrite phases. The compressive strength of the π-ferrosilicide phase is exceptionally high and does not yield despite loading in excess of 1.6 GPa. Such a high-strength silicide phase could not only provide a new type of strong, wear-resistant and corrosion-resistant Fe-based coating, replacing more costly and hazardous Co-based alloys for nuclear applications, but also lead to the development of a new class of high-performance silicide-strengthened stainless steels, no longer reliant on carbon for strengthening.

  12. Optimizing Wear Resistance and Impact Toughness in High Chromium Iron Mo-Ni Alloy

    NASA Astrophysics Data System (ADS)

    Singh, K. K.; Verma, R. S.; Murty, G. M. D.

    2009-06-01

    An alloy with carbon and chromium in the range of 2.0 to 2.5% and 20 to 25%, respectively, with the addition of Mo and Ni in the range of 1.0 to 1.5% each when heat-treated at a quenching temperature of 1010 °C and tempering temperature of 550 °C produces a hardness in the range of 54 to 56 HRC and a microstructure that consists of discontinuous bands of high volume (35-40%) of wear resistant primary (eutectic) carbides in a tempered martensitic matrix with uniformly dispersed secondary precipitates. This alloy has been found to possess adequate impact toughness (5-6 J/cm2) with a wear resistance of the order of 3-4 times superior to Mn steel and 1.25 times superior to martensitic stainless steel with a reduction in cost-to-life ratio by a factor of 1.25 in both the cases.

  13. Blast Coating of Superelastic NiTi Wire with PTFE to Enhance Wear Properties

    NASA Astrophysics Data System (ADS)

    Dunne, Conor F.; Roche, Kevin; Twomey, Barry; Hodgson, Darel; Stanton, Kenneth T.

    2015-03-01

    This work investigates the deposition of polytetrafluoroethylene (PTFE) onto a superelastic NiTi wire using an ambient temperature-coating technique known as CoBlast. The process utilises a stream of abrasive (Al2O3) and a coating medium (PTFE) sprayed simultaneously at the surface of the substrate. Superelastic NiTi wire is used in guidewire applications, and PTFE coatings are commonly applied to reduce damage to vessel walls during insertion and removal, and to aid in accurate positioning by minimising the force required to advance, retract or rotate the wire. The CoBlast coated wires were compared to wire treated with PTFE only. The coated samples were examined using variety of techniques: X-ray diffraction (XRD), microscopy, surface roughness, wear testing and flexural tests. The CoBlast coated samples had an adherent coating with a significant resistance to wear compared to the samples coated with PTFE only. The XRD revealed that the process gave rise to a stress-induced martensite phase in the NiTi which may enhance mechanical properties. The study indicates that the CoBlast process can be used to deposit thin adherent coatings of PTFE onto the surface of superelastic NiTi.

  14. Diamond and diamondlike carbon as wear-resistant, self-lubricating coatings for silicon nitride

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1995-01-01

    Recent work on the friction and wear properties of as-deposited fine-grain diamond, polished coarse-grain diamond, and as-deposited diamondlike carbon (DLC) films in humid air at a relative humidity of approximately 40 percent and in dry nitrogen is reviewed. Two types of chemical vapor deposition (CVD) processes are used to deposit diamond films on silicon nitride (Si3N4) substrates: microwave-plasma and hot-filament. Ion beams are used to deposit DLC films of Si3N4 substrates. The diamond and DLC films in sliding contact with hemispherical bare Si3N4 pins have low steady-state coefficients of friction (less than 0.2) and low wear rates (less than 10(exp -7) mm(exp 2)/N-m), and thus, can be used effectively as wear-resistant, self-lubricating coatings for Si3N4 in the aforementioned two environments.

  15. Skew And Twist Resistant Hydrodynamic Rotary Shaft Seal

    DOEpatents

    Dietle, Lannie; Kalsi, Manmohan Singh

    2000-03-14

    A hydrodynamically lubricated squeeze packing type rotary shaft seal suitable for lubricant retention and environmental exclusion which incorporates one or more resilient protuberances which and cooperate with the gland walls to hold the seal straight in its installation groove in unpressurized and low pressure lubricant retention applications thereby preventing skew-induced wear caused by impingement of abrasive contaminants present in the environment, and which also serve as radial bearings to prevent tipping of the seal within its installation gland. Compared to prior art, this invention provides a dramatic reduction of seal and shaft wear in abrasive environments and provides a significant increase in seal life.

  16. Alternate paddle configuration for improved wear resistance in the saltstone mixer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Reigel, M.; Fowley, M.

    The Saltstone Production Facility has a 10-inch Readco-Kurimoto continuous mixer that mixes the premix dry feeds and low-level waste salt solution to make fresh (uncured) saltstone. Inspection of the mixer in January 2013 showed significant wear on the third, fourth and fifth paddle pairs after the conveying augers. A 2-inch Readco-Kurimoto continuous mixer was used to test alternate paddle configurations for use in the 10-inch mixer to decrease the wear rate on the paddles. Two wear tests were conducted to investigate a method of reducing wear on the mixer paddles. The first test (wear test 2a) had a paddle configurationmore » similar to the currently installed 10-inch mixer in the SPF. This test established baseline wear. The second test (wear test 2b) had a reconfigured paddle arrangement that replaced the flat paddles with helical paddles for paddle pairs 2 - 6 and aligned paddle pair 1 with the augers. The intent of the reconfiguration was to more effectively convey the partially wetted dry feeds through the transition region and into the liquid feed where paddle wear is reduced due to dry feeds and salt solution being mixed at the intended water to premix ratio. The design of the helical paddles provides conveyance through the transition region to the liquid feed inlet. The alignment with the auger is aimed to provide a smoother transition (minimizing the discontinuity between the auger and paddle pair 1) into the downstream paddles. A soft metal with low wear resistance (6000 series aluminum) was used for the wear testing paddles to determine wear patterns while minimizing run time and maximizing wear rate. For the two paddle configurations tested using the scaled 2-inch Readco-Kurimoto continuous mixer, with the first six paddles after the augers replaced by the wear paddles and the remaining paddles were stainless steel. Since the 10-inch SPF mixer is designed with the liquid inlet centered over paddle pairs 5 and 6, the scaled 2-inch mixer was

  17. Wear Characteristics and Volume Loss of CAD/CAM Ceramic Materials.

    PubMed

    Zurek, Alec D; Alfaro, Maria F; Wee, Alvin G; Yuan, Judy Chia-Chun; Barao, Valentim A; Mathew, Mathew T; Sukotjo, Cortino

    2018-03-06

    higher volume loss than ZR (p < 0.001). For both glazed and polished finished, LD-G and LD-GP had significantly higher volume loss than ZR-G (p = 0.028), and ZR-GP (p < 0.001), respectively. SEM analysis indicated particle build-up and a grooving mechanism of wear for the LD-GP specimens. This suggested a three-body wear phenomenon occurring for LD-GP specimens, which was not visible in SEM imaging for other specimen types. This study demonstrated the resistance to wear and low abrasiveness of ZR when compared to LD in a simulated masticatory environment. This can be best explained by the increased strength of ZR, and the introduction of three-body wear to LD specimens from the accumulation of embedded wear debris onto its surface. Wear data and comparison of SEM images following wear simulation confirmed this interpretation. © 2018 by the American College of Prosthodontists.

  18. Wear resistance of Polymethyl Methacrylate (PMMA) with the Addition of Bone Ash, Hydroxylapatite and Keratin

    NASA Astrophysics Data System (ADS)

    Emre, G.; Akkus, A.; Karamış, M. B.

    2018-01-01

    In this study mechanichal and tribological properties of keratin, bone ash and hydroxylapatite by adding to PMMA ( known as the main prosthesis material) were investigated. Hydroxylapatite, bone ash, and keratin materials were added as PMMA in to the content of PMMA, in the proportions of %1, %3 and %5, respectively. The resulting mixtures were put into the molds and solidified in order to obtain samples to be used in the wear experiments. Each experiment was conducted by preparing three experimental samples. The wear data were compared according to the average values of the experimental samples. In the wear test, the results were also evaluated according to the average values obtained from each group and the results of the control group. It was observed that, the wear resistance of the PMMA including 3%, 5% bone ash and PMMA including 5% keratin flour were higher than the values of the control group.

  19. Recent advances in the mechanical durability of superhydrophobic materials.

    PubMed

    Milionis, Athanasios; Loth, Eric; Bayer, Ilker S

    2016-03-01

    Large majority of superhydrophobic surfaces have very limited mechanical wear robustness and long-term durability. This problem has restricted their utilization in commercial or industrial applications and resulted in extensive research efforts on improving resistance against various types of wear damage. In this review, advances and developments since 2011 in this field will be covered. As such, we summarize progress on fabrication, design and understanding of mechanically durable superhydrophobic surfaces. This includes an overview of recently published diagnostic techniques for probing and demonstrating tribo-mechanical durability against wear and abrasion as well as other effects such as solid/liquid spray or jet impact and underwater resistance. The review is organized in terms of various types of mechanical wear ranging from substrate adhesion, tangential surface abrasion, and dynamic impact to ultrasonic processing underwater. In each of these categories, we highlight the most successful approaches to produce robust surfaces that can maintain their non-wetting state after the wear or abrasive action. Finally, various recommendations for improvement of mechanical wear durability and its quantitative evaluation are discussed along with potential future directions towards more systematic testing methods which will also be acceptable for industry. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Effect of CeO₂ on Microstructure and Wear Resistance of TiC Bioinert Coatings on Ti6Al4V Alloy by Laser Cladding.

    PubMed

    Chen, Tao; Liu, Defu; Wu, Fan; Wang, Haojun

    2017-12-31

    To solve the lack of wear resistance of titanium alloys for use in biological applications, various prepared coatings on titanium alloys are often used as wear-resistant materials. In this paper, TiC bioinert coatings were fabricated on Ti6Al4V by laser cladding using mixed TiC and ZrO₂ powders as the basic pre-placed materials. A certain amount of CeO₂ powder was also added to the pre-placed powders to further improve the properties of the TiC coatings. The effects of CeO₂ additive on the phase constituents, microstructures and wear resistance of the TiC coatings were researched in detail. Although the effect of CeO₂ on the phase constituents of the coatings was slight, it had a significant effect on the microstructure and wear resistance of the coatings. The crystalline grains in the TiC coatings, observed by a scanning electron microscope (SEM), were refined due to the effect of the CeO₂. With the increase of CeO₂ additive content in the pre-placed powders, finer and more compact dendrites led to improvement of the micro-hardness and wear resistance of the TiC coatings. Also, 5 wt % content of CeO₂ additive in the pre-placed powders was the best choice for improving the wear properties of the TiC coatings.

  1. Corrosion-wear of β-Ti alloy TMZF (Ti-12Mo-6Zr-2Fe) in simulated body fluid.

    PubMed

    Yang, Xueyuan; Hutchinson, Christopher R

    2016-09-15

    Titanium alloys are popular metallic implant materials for use in total hip replacements. Although, α+β titanium alloys such as Ti-6Al-4V have been the most commonly used alloys, the high Young's modulus (∼110GPa) leads to an undesirable stress shielding effect. An alternative is to use β titanium alloys that exhibit a significantly lower Young's modulus (∼70GPa). Femoral stems made of a β titanium alloy known as TMZF (Ti-12Mo-6Zr-2Fe (wt.%)) have been used as part of modular hip replacements since the early 2000's but these were recalled in 2011 by the US Food & Drug Administration (FDA) due to unacceptable levels of 'wear debris'. The wear was caused by small relative movement of the stem and neck at the junction where they fit together in the modular hip replacement design. In this study, the corrosion and wear properties of the TMZF alloy were investigated in simulated body fluid to identify the reason for the wear debris generation. Ti64 was used as a control for comparison. It is shown that the interaction between the surfaces of Ti64 and TMZF with simulated body fluid is very similar, both from the point of view of the products formed and the kinetics of the reaction. The dry wear behaviour of TMZF is also close to that of Ti64 and consistent with expectations based on Archard's law for abrasive wear. However, wear of Ti64 and TMZF in simulated body fluid show contrasting behaviours. A type of time-dependent wear test is used to examine the synergy between corrosion and wear of TMZF and Ti64. It is shown that the wear of TMZF accelerated rapidly in SBF whereas that of Ti64 is reduced. The critical role of the strain hardening capacity of the two materials and its role in helping the surface resist abrasion by hydroxyapatite particles formed as a result of the reaction with the SBF is discussed and recommendations are made for modifications that could be made to the TMZF alloy to improve the corrosion-wear response. TMZF is a low modulus β-Ti alloy

  2. Mechanical and tribological properties of thermally sprayed tungsten carbide-cobalt coatings

    NASA Astrophysics Data System (ADS)

    Qiao, Yunfei

    Since previous work in our laboratory has shown that very fine microstructures increase the hardness and the resistance to sliding and abrasive wear of bulk, sintered, WC/Co composites, it was decided to explore whether similar benefits can be obtained in coatings of this material deposited by the Thermal Spray Method. The research was a collaborative effort in which a number of companies and universities prepared feedstock powders by a number of methods and deposited coatings by Plasma Spray and High Velocity Oxy Fuel spray techniques. Our role was to study the resistance of these coatings to abrasion and to wear in unlubricated sliding, to relate our findings to the microstructure of the coatings and to the properties of the powder and the parameters of deposition. The results were then used by our partners in the program to modify their processes in order to obtain the best possible performance. The thesis consists of four parts. In the first, we review the literature on WC/Co coatings and present the results of our survey of 45 coatings. This shows that the details of the thermal spray technique determine the tribological performance of the coatings much more than the size of the WC grains in the starting powder. It also shows that abrasive and sliding wear respond differently to the material properties. The remainder of the thesis describes a systematic variation of powders and deposition techniques, based on our earlier findings. In the second part, we describe the microstructures, hardness and toughness of nine coatings deposited by A. Dent at SUNY Stony Brook, with three different powders and three different flame chemistries. We find that the hardness is determined mainly by the flame temperature; hardness is decreased by porosity on the 50-nm size range, and this porosity is produced by insufficient melting of the Co binder. High temperatures and certain powder morphologies cause extensive decarburization, and the latter reduces the adhesion between the

  3. Enhancement of the wear resistance and microhardness of aluminum alloy by Nd:YaG laser treatment.

    PubMed

    Hussein, Haitham T; Kadhim, Abdulhadi; Al-Amiery, Ahmed A; Kadhum, Abdul Amir H; Mohamad, Abu Bakar

    2014-01-01

    Influence of laser treatment on mechanical properties, wear resistance, and Vickers hardness of aluminum alloy was studied. The specimens were treated by using Nd:YaG laser of energy 780 mj, wavelength 512 nm, and duration time 8 ns. The wear behavior of the specimens was studied for all specimens before and after treatment by Nd:YaG laser and the dry wear experiments were carried out by sing pinon-disc technique. The specimens were machined as a disk with diameter of 25 mm and circular groove in depth of 3 mm. All specimens were conducted by scanning electron microscopy (SEM), energy-dispersive X-ray fluorescence analysis (EDS), optical microscopy, and Vickers hardness. The results showed that the dry wear rate was decreased after laser hardening and increased Vickers hardness values by ratio of 2.4:1. The results showed that the values of wear rate for samples having circular grooves are less than samples without grooves after laser treatment.

  4. Wear Resistant Coatings for Titanium.

    DTIC Science & Technology

    1980-07-01

    FISHTER NOOO1978-C-0889 UNCLASSIFIED PWA-FR-12303 NLlmhhhEEEEI, 111w .06 11112 1.1 4 Q MICROCOP AESOLUPON TEST CHART NATIONAL. BUREAU Of STANDARDS 1963... Compound ," ~ 113 g/22.7 kg (4 oz/50 Ib) Corrosion Inhibitor" ~ 4 mI/I (15 mI/gal) I. Fill tank to about of operating level with water 2. Add abrasive...slowly while circulating pump is on :. Add antisolidifying compound 4. Add corrosion inhibitor 5. F~ill to operating level. Etch Solution Hydrofluoric

  5. Wheel Abrasion Experiment Metals Selection for Mars Pathfinder Mission

    NASA Technical Reports Server (NTRS)

    Hepp, Aloysius F.; Fatemi, Navid S.; Wilt, David M.; Ferguson, Dale C.; Hoffman, Richard; Hill, Maria M.; Kaloyeros, Alain E.

    1996-01-01

    A series of metals was examined for suitability for the Wheel Abrasion Experiment, one of ten microrover experiments of the Mars Pathfinder Mission. The seven candidate metals were: Ag, Al, Au, Cu, Ni, Pt, and W. Thin films of candidate metals from 0.1 to 1.0 micrometer thick were deposited on black anodized aluminum coupons by e-beam and resistive evaporation and chemical vapor deposition. Optical, corrosion, abrasion, and adhesion criteria were used to select Al, Ni, and Pt. A description is given of the deposition and testing of thin films, followed by a presentation of experimental data and a brief discussion of follow-on testing and flight qualification.

  6. High temperature wear performance of HVOF-sprayed Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr hardmetal coatings

    NASA Astrophysics Data System (ADS)

    Zhou, Wuxi; Zhou, Kesong; Li, Yuxi; Deng, Chunming; Zeng, Keli

    2017-09-01

    A novel Cr3C2-WC-NiCoCrMo and commercial Cr3C2-NiCr thermal spray-grade powders with particle size of -45 + 15 μm were prepared by an agglomeration and sintering process. Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr coatings were deposited by high velocity oxygen fuel (HVOF) spraying. The fundamental properties of both coatings were evaluated and friction wear test against Al2O3 counterbodies of both coatings at high temperatures (450 °C, 550 °C, 650 °C) were carried out ball-on-disk high temperature tribometer. All specimens were characterized by optical microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) and 3D non-contact surface mapping profiler. The results have shown that the Cr3C2-WC-NiCoCrMo coating exhibited lower porosity, higher micro-hardness compared to the Cr3C2-NiCr coating. The Cr3C2-WC-NiCoCrMo coating also exhibited better wear resistance and higher friction coefficient compared to the Cr3C2-NiCr coating when sliding against the Al2O3 counterpart. Wear rates of both coatings increased with raising temperature. Both coatings experienced abrasive wear; hard phase particles (WC and Cr3C2) with different sizes, distributed in the matrix phase, will effectively improve the resistance against wear at high temperatures.

  7. The protective effect of SnF2 containing toothpastes and solution on enamel surfaces subjected to erosion and abrasion in situ.

    PubMed

    Hove, L H; Stenhagen, K R; Holme, B; Tveit, A B

    2014-08-01

    Stannous fluoride solutions have shown promising protective effect against erosion/abrasion, but the effect of SnF2 toothpastes is uncertain. The aim of the study was to test the inhibiting effect of two SnF2 toothpastes and a SnF2 solution against erosive/abrasive wear in a single-blind, randomised in situ study, using a white light interferometer. Sixteen human molars were each divided into four specimens, mounted on mouth appliances and worn by 8 volunteers for 9 days. Specimens were brushed with toothpaste twice each day for 30 s either with fluoride-free toothpaste or toothpastes including SnF2. Toothpaste was left on the surface for 90 additional seconds. Group 1, fluoride-free toothpaste; Group 2, toothpaste A (0.4% SnF2, Solidox); Group 3, toothpaste B (0.454 % SnF2, Oral-B(®)); Group 4, brushed with fluoride-free toothpaste (30 s) and treated for 2 min with a 0.4 % SnF2 solution (1,000 ppm F). To mimic gastric reflux/vomit, specimens were etched for 2 min twice a day (0.01 M HCl). Procedures were performed extra-orally. The mean enamel wear (in μm) for the control specimens was: -29.2 ± SD 10.5; for group 2 -14.5 SD ± 9.3; for group 3 -33.3 SD ± 7.4, and for group 4 +0.4 SD ± 1.3. The specimens treated with SnF2 solution and toothpaste A showed significantly lower enamel wear than the control group. Toothpaste B gave no significant reduction in enamel wear. The SnF2 solution fully protected the enamel surface against erosive and abrasive challenges. The SnF2 toothpaste A (Solidox) showed less, but significant protection of the enamel, while no statistically significant protection was demonstrated by SnF2 toothpaste B (Oral-B(®) Pro-Expert).

  8. Wear Mechanism of Chemical Vapor Deposition (CVD) Carbide Insert in Orthogonal Cutting Ti-6Al-4V ELI at High Cutting Speed

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gusri, A. I.; Che Hassan, C. H.; Jaharah, A. G.

    2011-01-17

    The performance of Chemical Vapor Deposition (CVD) carbide insert with ISO designation of CCMT 12 04 04 LF, when turning titanium alloys was investigated. There were four layers of coating materials for this insert i.e.TiN-Al2O3-TiCN-TiN. The insert performance was evaluated based on the insert's edge resistant towards the machining parameters used at high cutting speed range of machining Ti-6Al-4V ELI. Detailed study on the wear mechanism at the cutting edge of CVD carbide tools was carried out at cutting speed of 55-95 m/min, feed rate of 0.15-0.35 mm/rev and depth of cut of 0.10-0.20 mm. Wear mechanisms such as abrasivemore » and adhesive were observed on the flank face. Crater wear due to diffusion was also observed on the rake race. The abrasive wear occurred more at nose radius and the fracture on tool were found at the feed rate of 0.35 mm/rev and the depth of cut of 0.20 mm. The adhesion wear takes place after the removal of the coating or coating delaminating. Therefore, adhesion or welding of titanium alloy onto the flank and rake faces demonstrates a strong bond at the workpiece-tool interface.« less

  9. Conjoint corrosion and wear in titanium alloys.

    PubMed

    Khan, M A; Williams, R L; Williams, D F

    1999-04-01

    When considering titanium alloys for orthopaedic applications it is important to examine the conjoint action of corrosion and wear. In this study we investigate the corrosion and wear behaviour of Ti-6Al-4V, Ti-6Al-7Nb and Ti-13Nb-13Zr in phosphate buffered saline (PBS), bovine albumin solutions in PBS and 10% foetal calf serum solutions in PBS. The tests were performed under four different conditions to evaluate the influence of wear on the corrosion and corrosion on the wear behaviour as follows: corrosion without wear, wear-accelerated corrosion, wear in a non-corrosive environment and wear in a corrosive environment. The corrosion behaviour was investigated using cyclic polarisation studies to measure the ability of the surface to repassivate following breakdown of the passive layer. The properties of the repassivated layer were evaluated by measuring changes in the surface hardness of the alloys. The amount of wear that had occurred was assessed from weight changes and measurement of the depth of the wear scar. It was found that in the presence of wear without corrosion the wear behaviour of Ti-13Nb-13Zr was greater than that of Ti-6Al-7Nb or Ti-6Al-4V and that in the presence of proteins the wear of all three alloys is reduced. In the presence of corrosion without wear Ti-13Nb-13Zr was more corrosion resistant than Ti-6Al-7Nb which was more corrosion resistant than Ti-6Al-4V without proteins whereas in the presence of protein the corrosion resistance of Ti-13Nb-13Zr and Ti-6Al-7Nb was reduced and that of Ti-6Al-4V increased. In the presence of corrosion and wear the corrosion resistance of Ti-13Nb-13Zr is higher than that of Ti-6Al-7Nb or Ti-6Al-4V in PBS but in the presence of proteins the corrosion resistance of Ti-13Nb-13Zr and Ti-6Al-7Nb are very similar but higher than that of Ti-6Al-4V. The wear of Ti-13Nb-13Zr is lower than that of Ti-6Al-7Nb and Ti-6Al-4V with or without the presence of proteins in a corrosive environment. Therefore the overall

  10. NASA interdisciplinary collaboration in tribology. A review of oxidational wear

    NASA Technical Reports Server (NTRS)

    Quinn, T. F. J.

    1983-01-01

    An in-depth review of oxidational wear of metals is presented. Special emphasis is given to a description of the concept of oxidational wear and the formulation of an Oxidational Wear Theory. The parallelism between the formation of an oxide film for dry contact conditions and the formation of other surface films for a lubricated contact is discussed. The description of oxidational wear is prefaced with a unification of wear modes into two major classes of mild and severe wear including both lubricated and dry contacts. Oxidational wear of metals is a class of mild wear where protective oxide films are formed at real areas of contact and during the time of contact at temperataure T sub c. When the oxide reaches a critical thickness, frequently in the range of 1 to 3 microns, the oxide breaks up and eventually appears as a wear particle. These oxides are preferentially formed on plateaux which alternately carry the load as they reach their critical thickness and are removed. If the system is operated at elevated temperatures, thick oxides can form both out of contact and between the plateaux. Temperature is important in determining the structure of the oxide film present. Spinel oxide (Fe3O4) which forms above 300 C is more protective than the lower temperature rhomobohedral (alpha-Fe2O3) oxide which is abrasive. An Oxidational Wear Theory is derived using a modified Archard wear law expressed in terms of activation energy (Qp) and Arrhenius constant (Ap).

  11. Effect of CeO2 on Microstructure and Wear Resistance of TiC Bioinert Coatings on Ti6Al4V Alloy by Laser Cladding

    PubMed Central

    Wang, Haojun

    2017-01-01

    To solve the lack of wear resistance of titanium alloys for use in biological applications, various prepared coatings on titanium alloys are often used as wear-resistant materials. In this paper, TiC bioinert coatings were fabricated on Ti6Al4V by laser cladding using mixed TiC and ZrO2 powders as the basic pre-placed materials. A certain amount of CeO2 powder was also added to the pre-placed powders to further improve the properties of the TiC coatings. The effects of CeO2 additive on the phase constituents, microstructures and wear resistance of the TiC coatings were researched in detail. Although the effect of CeO2 on the phase constituents of the coatings was slight, it had a significant effect on the microstructure and wear resistance of the coatings. The crystalline grains in the TiC coatings, observed by a scanning electron microscope (SEM), were refined due to the effect of the CeO2. With the increase of CeO2 additive content in the pre-placed powders, finer and more compact dendrites led to improvement of the micro-hardness and wear resistance of the TiC coatings. Also, 5 wt % content of CeO2 additive in the pre-placed powders was the best choice for improving the wear properties of the TiC coatings. PMID:29301218

  12. Concrete surface with nano-particle additives for improved wearing resistance to increasing truck traffic.

    DOT National Transportation Integrated Search

    2012-07-01

    This study focused on the use of nanotechnology in concrete to improve the wearing resistance of concrete. The nano : materials used were polymer cross-linked aerogels, carbon nanotubes, and nano-SiO2, nano-CaCO3, and nano-Al2O3 : particles. As an in...

  13. Simulation of tibial counterface wear in mobile bearing knees with uncoated and ADLC coated surfaces.

    PubMed

    Jones, V C; Barton, D C; Auger, D D; Hardaker, C; Stone, M H; Fisher, J

    2001-01-01

    A multidirectional pin-on-plate reciprocating machine was used to compare the wear performance of UHMWPE sliding against cast cobalt chrome (CoCr) plates that were either untreated or coated with Amorphous Diamond Like Carbon (ADLC). The test conditions were based on a 1/5 scale model representative of in vivo motion at the tibial counterfaces of unconstrained mobile bearing knees. The average +/- STERR wear rates were 13.78+/-1.06 mm3/Mcycles for the ADLC counterfaces and 0.504+/-0.12 mm3/Mcycles for the control CoCr counterfaces. All of the pins run on the ADLC counterfaces exhibited the same patterns of blistering along the central axis, and severe abrasion elsewhere to the extent that all of the original machining marks were removed after just one week of testing. The average value of friction coefficient was 0.24 for the ADLC counterfaces and 0.073 for the control CoCr counterfaces. The factor of 3.5 increase was statistically significant at p < 0.05. In the tribological evaluation of ADLC coatings for tibial trays in mobile bearing knees, this study shows that this specific Physical Vapour Deposition (PVD) ADLC showed significantly poorer frictional and wear performance than uncoated surfaces which was sufficient to negate any potential benefits of improved resistance to third body damage.

  14. Wear and Corrosion Resistance of Thick Ti-6Al-4V Coating Deposited on Ti-6Al-4V Substrate via High-Pressure Cold Spray

    NASA Astrophysics Data System (ADS)

    Khun, N. W.; Tan, A. W. Y.; Sun, W.; Liu, E.

    2017-08-01

    Ti-6Al-4V (Ti64) coating with a thickness of about 9 mm was deposited on commercial Ti64 substrate via a high-pressure cold spray process. The microstructure, hardness, and wear and corrosion resistance of the Ti64 coating were systematically investigated. The hardness of the Ti64 coating was higher than that of the Ti64 substrate due to the cold-worked microstructure of the coating. The tribological results showed that there was no significant difference in the surface wear rates of the Ti64 coating measured on its different layers while the surface wear resistance of the Ti64 coating was lower than its cross-sectional wear resistance. The corrosion results showed that the Ti64 coating did not effectively prevent its underlying Ti64 substrate from corrosion due to the occurrence of pores in the coating microstructure. It could be concluded that the hardness and wear resistance of the Ti64 coating were comparable to those of the commercial Ti64 substrate.

  15. Investigation on the relationship between NbC and wear-resistance of Fe matrix composite coatings with different C contents

    NASA Astrophysics Data System (ADS)

    Zhao, Changchun; Zhou, Yefei; Xing, Xiaolei; Liu, Sha; Ren, Xuejun; Yang, Qingxiang

    2018-05-01

    The wear resistance of Fe-based composite coating is significantly related with the character of carbides and matrix, which could be strongly affected by C content in it. In this work, the Fe-based composite coatings with different C contents were prepared. The microstructure and phase structure of the coatings were analyzed by scanning electron microscope (SEM) equipped with an energy-dispersive spectroscopy (EDS) and X-ray diffractometer (XRD). The hardness and wear resistance of the coatings were determined. Then the hardness and brittleness of carbon poor niobium carbides were calculated by first principles calculation. The results show that, the phase structures of the coatings are mainly composed of NbC, γ phase (retained austenite) and α phase (martensite). With the increase of C content, the retained austenite appears and C content of martensite is increased. The hardness of the coatings are increased from HRC 22 to HRC 59. The distribution and morphology of NbC are changed with the increase of C content. The NbC precipitated in reticular grain boundary can be observed when C content is 0.4 wt.% C (C-1). NbC turn into granular and small rod morphology when C content increases to 0.8 wt.% C (C-2). The cracks and defects cannot been found on the surface of the coating when C content is 1.2 wt.% C(C-3), whose hardness is HRC 58 and wear loss is 0.27 g/N cm2 in 8 h. The flaky M7C3 carbide precipitates on the coating when C content is 1.4 wt.% C(C-4), which weaken the wear resistance of the matrix. Compared with the hardfacing coatings with different C contents, the C-3 coating processes higher hardness and wear resistance.

  16. Wear Characteristics and Mechanisms of H13 Steel with Various Tempered Structures

    NASA Astrophysics Data System (ADS)

    Cui, X. H.; Wang, S. Q.; Wei, M. X.; Yang, Z. R.

    2011-08-01

    Wear tests of H13 steel with various tempering microstructures were performed under atmospheric conditions at room temperature (RT), 200 °C, and 400 °C. The wear characteristics and wear mechanisms of various tempered microstructures of the steel were focused by investigating the structure, morphology, and composition of the worn surfaces. Under atmospheric conditions at RT, 200 °C, and 400 °C, adhesive wear, mild oxidation wear, and oxidation wear prevailed, respectively. The wear rate at 200 °C was substantially lower than those at RT and 400 °C due to the protection of tribo-oxides. In mild oxidation wear, the tempered microstructures of the steel presented almost no obvious influence on the wear resistance. However, in adhesive wear and oxidation wear, the wear resistance strongly depended on the tempered microstructures of the steel. The steel tempered at 600-650 °C presented pronouncedly lower wear rates than the one tempered at 200-550 or 700 °C. It can be suggested that the wear resistance of the steel was closely related with its fracture resistance.

  17. Structural-phase states and wear resistance of surface formed on steel by surfacing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kapralov, Evgenie V.; Raykov, Sergey V.; Vaschuk, Ekaterina S.

    2014-11-14

    Investigations of elementary and phase structure, state of defect structure and tribological characteristics of a surfacing, formed on a low carbon low-alloy steel by a welding method were carried out. It was revealed that a surfacing, formed on a steel surface is accompanied by the multilayer formation, and increases the wear resistance of the layer surfacing as determined.

  18. Enhancement of wear and corrosion resistance of beta titanium alloy by laser gas alloying with nitrogen

    NASA Astrophysics Data System (ADS)

    Chan, Chi-Wai; Lee, Seunghwan; Smith, Graham; Sarri, Gianluca; Ng, Chi-Ho; Sharba, Ahmed; Man, Hau-Chung

    2016-03-01

    The relatively high elastic modulus coupled with the presence of toxic vanadium (V) in Ti6Al4V alloy has long been a concern in orthopaedic applications. To solve the problem, a variety of non-toxic and low modulus beta-titanium (beta-Ti) alloys have been developed. Among the beta-Ti alloy family, the quaternary Ti-Nb-Zr-Ta (TNZT) alloys have received the highest attention as a promising replacement for Ti6Al4V due to their lower elastic modulus and outstanding long term stability against corrosion in biological environments. However, the inferior wear resistance of TNZT is still a problem that must be resolved before commercialising in the orthopaedic market. In this work, a newly developed laser surface treatment technique was employed to improve the surface properties of Ti-35.3Nb-7.3Zr-5.7Ta alloy. The surface structure and composition of the laser-treated TNZT surface were examined by grazing incidence X-ray diffraction (GI-XRD) and X-ray photoelectron spectroscopy (XPS). The wear and corrosion resistance were evaluated by pin-on-plate sliding test and anodic polarisation test in Hanks' solution. The experimental results were compared with the untreated (or base) TNZT material. The research findings showed that the laser surface treatment technique reported in this work can effectively improve the wear and corrosion resistance of TNZT.

  19. Enhancement of the Wear Resistance and Microhardness of Aluminum Alloy by Nd:YaG Laser Treatment

    PubMed Central

    Hussein, Haitham T.; Kadhim, Abdulhadi; Al-Amiery, Ahmed A.; Kadhum, Abdul Amir H.; Mohamad, Abu Bakar

    2014-01-01

    Influence of laser treatment on mechanical properties, wear resistance, and Vickers hardness of aluminum alloy was studied. The specimens were treated by using Nd:YaG laser of energy 780 mj, wavelength 512 nm, and duration time 8 ns. The wear behavior of the specimens was studied for all specimens before and after treatment by Nd:YaG laser and the dry wear experiments were carried out by sing pinon-disc technique. The specimens were machined as a disk with diameter of 25 mm and circular groove in depth of 3 mm. All specimens were conducted by scanning electron microscopy (SEM), energy-dispersive X-ray florescence analysis (EDS), optical microscopy, and Vickers hardness. The results showed that the dry wear rate was decreased after laser hardening and increased Vickers hardness values by ratio of 2.4 : 1. The results showed that the values of wear rate for samples having circular grooves are less than samples without grooves after laser treatment. PMID:25136694

  20. Effects of Deep Cryogenic Treatment on the Wear Resistance and Mechanical Properties of AISI H13 Hot-Work Tool Steel

    NASA Astrophysics Data System (ADS)

    Çiçek, Adem; Kara, Fuat; Kıvak, Turgay; Ekici, Ergün; Uygur, İlyas

    2015-11-01

    In this study, a number of wear and tensile tests were performed to elucidate the effects of deep cryogenic treatment on the wear behavior and mechanical properties (hardness and tensile strength) of AISI H13 tool steel. In accordance with this purpose, three different heat treatments (conventional heat treatment (CHT), deep cryogenic treatment (DCT), and deep cryogenic treatment and tempering (DCTT)) were applied to tool steel samples. DCT and DCTT samples were held in nitrogen gas at -145 °C for 24 h. Wear tests were conducted on a dry pin-on-disk device using two loads of 60 and 80 N, two sliding velocities of 0.8 and 1 m/s, and a wear distance of 1000 m. All test results showed that DCT improved the adhesive wear resistance and mechanical properties of AISI H13 steel. The formation of small-sized and uniformly distributed carbide particles and the transformation of retained austenite to martensite played an important role in the improvements in the wear resistance and mechanical properties. After cleavage fracture, the surfaces of all samples were characterized by the cracking of primary carbides, while the DCT and DCTT samples displayed microvoid formation by decohesion of the fine carbides precipitated during the cryo-tempering process.

  1. A Profilometry-Based Dentifrice Abrasion Method for V8 Brushing Machines Part II: Comparison of RDA-PE and Radiotracer RDA Measures.

    PubMed

    Schneiderman, Eva; Colón, Ellen; White, Donald J; St John, Samuel

    2015-01-01

    The purpose of this study was to compare the abrasivity of commercial dentifrices by two techniques: the conventional gold standard radiotracer-based Radioactive Dentin Abrasivity (RDA) method; and a newly validated technique based on V8 brushing that included a profilometry-based evaluation of dentin wear. This profilometry-based method is referred to as RDA-Profilometry Equivalent, or RDA-PE. A total of 36 dentifrices were sourced from four global dentifrice markets (Asia Pacific [including China], Europe, Latin America, and North America) and tested blindly using both the standard radiotracer (RDA) method and the new profilometry method (RDA-PE), taking care to follow specific details related to specimen preparation and treatment. Commercial dentifrices tested exhibited a wide range of abrasivity, with virtually all falling well under the industry accepted upper limit of 250; that is, 2.5 times the level of abrasion measured using an ISO 11609 abrasivity reference calcium pyrophosphate as the reference control. RDA and RDA-PE comparisons were linear across the entire range of abrasivity (r2 = 0.7102) and both measures exhibited similar reproducibility with replicate assessments. RDA-PE assessments were not just linearly correlated, but were also proportional to conventional RDA measures. The linearity and proportionality of the results of the current study support that both methods (RDA or RDA-PE) provide similar results and justify a rationale for making the upper abrasivity limit of 250 apply to both RDA and RDA-PE.

  2. Modeling and Tool Wear in Routing of CFRP

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Iliescu, D.; Fernandez, A.; Gutierrez-Orrantia, M. E.

    2011-01-17

    This paper presents the prediction and evaluation of feed force in routing of carbon composite material. In order to extend tool life and improve quality of the machined surface, a better understanding of uncoated and coated tool behaviors is required. This work describes (1) the optimization of the geometry of multiple teeth tools minimizing the tool wear and the feed force, (2) the optimization of tool coating and (3) the development of a phenomenological model between the feed force, the routing parameters and the tool wear. The experimental results indicate that the feed rate, the cutting speed and the toolmore » wear are the most significant factors affecting the feed force. In the case of multiple teeth tools, a particular geometry with 14 teeth right helix right cut and 11 teeth left helix right cut gives the best results. A thick AlTiN coating or a diamond coating can dramatically improve the tool life while minimizing the axial force, roughness and delamination. A wear model has then been developed based on an abrasive behavior of the tool. The model links the feed rate to the tool geometry parameters (tool diameter), to the process parameters (feed rate, cutting speed and depth of cut) and to the wear. The model presented has been verified by experimental tests.« less

  3. Research on operation mode of abrasive grain during grinding

    NASA Astrophysics Data System (ADS)

    Ivanova, T. N.; Dement’ev, V. B.; Nikitina, O. V.

    2018-03-01

    The processing of materials by cutting with an abrasive tool is carried out by means of thousands of grains bonded together as a single whole. The quality of the abrasive tool is defined by cutting properties of abrasive grains and depends on features of spreading the temperature field in time and in the abrasive grain volume. Grains are exposed to heating and cooling during work. It leads to undesired effects such as a decrease of durability of grain retention in the binder, hardness, intensification of diffusion and oxidation processes between the binder and the grain, the occurrence of considerable temperature stresses in the grain itself. The obtained equation which allows calculation of temperature field of grain for one rotation of grinding wheel shows that the temperature of the wheel depends on grinding modes and thermophysical properties of abrasive material. Thus, as the time of contact of grain with processed material increases, the temperature in the cutting area rises. As thermophysical properties increase, the temperature in cutting area decreases. Thermal working conditions are determined to be different from each other depending on contact time of the grain and the material. For example, in case of creep-feed grinding, the peak value of temperature is higher than during multistep grinding; the depth of expansion is greater. While the speed of the thermal process in creep-feed grinding is 2-3 times lower than in multistep grinding, the gradient reduces 3-4 times. The analysis of machining methods shows that creep-feed grinding ensures greater depth of grain heating, a smaller heating rate and a reduced velocity gradient. It causes a decrease of probable allotropic modifications and prevents from occurring of heat strokes - cracking of grains due to high temperature falls. Consequently, it is necessary to employ creep-feed grinding to increase the efficiency of abrasive tool employing. Three operation modes of grinding wheel including blunting, full

  4. Improvement of Scratch and Wear Resistance of Polymers by Fillers Including Nanofillers

    PubMed Central

    Brostow, Witold; Lobland, Haley E. Hagg; Hnatchuk, Nathalie; Perez, Jose M.

    2017-01-01

    Polymers have lower resistance to scratching and wear than metals. Liquid lubricants work well for metals but not for polymers nor for polymer-based composites (PBCs). We review approaches for improvement of tribological properties of polymers based on inclusion of fillers. The fillers can be metallic or ceramic—with obvious consequences for electrical resistivity of the composites. Distinctions between effectiveness of micro- versus nano-particles are analyzed. For example, aluminum nanoparticles as filler are more effective for property improvement than microparticles at the same overall volumetric concentration. Prevention of local agglomeration of filler particles is discussed along with a technique to verify the prevention. PMID:28336900

  5. Modeling and Investigation of the Wear Resistance of Salt Bath Nitrided Aisi 4140 via ANN

    NASA Astrophysics Data System (ADS)

    Ekinci, Şerafettin; Akdemir, Ahmet; Kahramanli, Humar

    2013-05-01

    Nitriding is usually used to improve the surface properties of steel materials. In this way, the wear resistance of steels is improved. We conducted a series of studies in order to investigate the microstructural, mechanical and tribological properties of salt bath nitrided AISI 4140 steel. The present study has two parts. For the first phase, the tribological behavior of the AISI 4140 steel which was nitrided in sulfinuz salt bath (SBN) was compared to the behavior of the same steel which was untreated. After surface characterization using metallography, microhardness and sliding wear tests were performed on a block-on-cylinder machine in which carbonized AISI 52100 steel discs were used as the counter face. For the examined AISI 4140 steel samples with and without surface treatment, the evolution of both the friction coefficient and of the wear behavior were determined under various loads, at different sliding velocities and a total sliding distance of 1000 m. The test results showed that wear resistance increased with the nitriding process, friction coefficient decreased due to the sulfur in salt bath and friction coefficient depended systematically on surface hardness. For the second part of this study, four artificial neural network (ANN) models were designed to predict the weight loss and friction coefficient of the nitrided and unnitrided AISI 4140 steel. Load, velocity and sliding distance were used as input. Back-propagation algorithm was chosen for training the ANN. Statistical measurements of R2, MAE and RMSE were employed to evaluate the success of the systems. The results showed that all the systems produced successful results.

  6. Microstructure and wear resistance of laser cladded Ni-Cr-Co-Ti-V high-entropy alloy coating after laser remelting processing

    NASA Astrophysics Data System (ADS)

    Cai, Zhaobing; Cui, Xiufang; Liu, Zhe; Li, Yang; Dong, Meiling; Jin, Guo

    2018-02-01

    An attempt, combined with the technologies of laser cladding and laser remelting, has been made to develop a Ni-Cr-Co-Ti-V high entropy alloy coating. The phase composition, microstructure, micro-hardness and wear resistance (rolling friction) were studied in detail. The results show that after laser remelting, the phase composition remains unchanged, that is, as-cladded coating and as-remelted coatings are all composed of (Ni, Co)Ti2 intermetallic compound, Ti-rich phase and BCC solid solution phase. However, after laser remelting, the volume fraction of Ti-rich phase increases significantly. Moreover, the micro-hardness is increased, up to ∼900 HV at the laser remelting parameters: laser power of 1 kW, laser spot diameter of 3 mm, and laser speed of 10 mm/s. Compared to the as-cladded high-entropy alloy coating, the as-remelted high-entropy alloy coatings have high friction coefficient and low wear mass loss, indicating that the wear resistance of as-remelted coatings is improved and suggesting practical applications, like coatings on brake pads for wear protection. The worn surface morphologies show that the worn mechanism of as-cladded and as-remelted high-entropy alloy coatings are adhesive wear.

  7. Microstructural changes and strain hardening effects in abrasive contacts at different relative velocities and temperatures

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rojacz, H., E-mail: rojacz@ac2t.at

    2016-08-15

    Strain hardening is commonly used to reach the full potential of materials and can be beneficial in tribological contacts. 2-body abrasive wear was simulated in a scratch test, aimed at strain hardening effects in various steels. Different working conditions were examined at various temperatures and velocities. Strain hardening effects and microstructural changes were analysed with high resolution scanning electron microscopy (HRSEM), electron backscatter diffraction (EBSD), micro hardness measurements and nanoindentation. Statistical analysing was performed quantifying the influence of different parameters on microstructures. Results show a crucial influence of temperature and velocity on the strain hardening in tribological contacts. Increased velocitymore » leads to higher deformed microstructures and higher increased surface hardness at a lower depth of the deformed zones at all materials investigated. An optimised surface hardness can be achieved knowing the influence of velocity (strain rate) and temperature for a “tailor-made” surface hardening in tribological systems aimed at increased wear resistance. - Highlights: •Hardening mechanisms and their intensity in tribological contacts are dependent on relative velocity and temperature. •Beneficial surface hardened zones are formed at certain running-in conditions; the scientific background is presented here. •Ferritic-pearlitic steels strain hardens via grain size reduction and decreasing interlamellar distances in pearlite. •Austenitic steels show excellent surface hardening (120% hardness increase) by twinning and martensitic transformation. •Ferritic steels with hard phases harden in the ferrite phase as per Hall-Petch equation and degree of deformation.« less

  8. Dental abrasion as a cutting process.

    PubMed

    Lucas, Peter W; Wagner, Mark; Al-Fadhalah, Khaled; Almusallam, Abdulwahab S; Michael, Shaji; Thai, Lidia A; Strait, David S; Swain, Michael V; van Casteren, Adam; Renno, Waleed M; Shekeban, Ali; Philip, Swapna M; Saji, Sreeja; Atkins, Anthony G

    2016-06-06

    A mammalian tooth is abraded when a sliding contact between a particle and the tooth surface leads to an immediate loss of tooth tissue. Over time, these contacts can lead to wear serious enough to impair the oral processing of food. Both anatomical and physiological mechanisms have evolved in mammals to try to prevent wear, indicating its evolutionary importance, but it is still an established survival threat. Here we consider that many wear marks result from a cutting action whereby the contacting tip(s) of such wear particles acts akin to a tool tip. Recent theoretical developments show that it is possible to estimate the toughness of abraded materials via cutting tests. Here, we report experiments intended to establish the wear resistance of enamel in terms of its toughness and how friction varies. Imaging via atomic force microscopy (AFM) was used to assess the damage involved. Damage ranged from pure plastic deformation to fracture with and without lateral microcracks. Grooves cut with a Berkovich diamond were the most consistent, suggesting that the toughness of enamel in cutting is 244 J m(-2), which is very high. Friction was higher in the presence of a polyphenolic compound, indicating that this could increase wear potential.

  9. Wear-resistance investigation of electro-screen coatings obtained using electroerosive powders of micro and nanofractions

    NASA Astrophysics Data System (ADS)

    Ageev, E. V.; Altukhov, A. Yu; Malneva, Yu V.; Novikov, A. N.

    2018-03-01

    The results of the wear resistance investigation of electro sparking coatings, applied using electrode material from electroerosive powders of hard alloy VK-8 (90%) with the addition of powder of high-speed steel of grade R6M5 (10%), are presented. Electro spark coatings were formed on samples of 30KhGSA steel using these electrodes and installation UR-121. The coefficient of friction and the wear rate of the surface of the sample and counterbody were measured on an automated friction machine “Tribometer” (CSM Instruments, Switzerland), controlled by a computer, according to the standard “ball-disk” test scheme.

  10. Sliding Wear and Fretting Wear of DLC-Based, Functionally Graded Nanocomposite Coatings

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Pohlchuck, B.; Street, Kenneth W.; Zabinski, J. S.; Sanders, J. H.; Voevodin, A. a.; Wu, R. L. C.

    1999-01-01

    Improving the tribological functionality of diamondlike carbon (DLC) films--developing, good wear resistance, low friction, and high load-carrying capacity-was the aim of this investigation. Nanocomposite coatings consisting of an amorphous DLC (a-DLC) top layer and a functionally graded titanium-titanium carbon-diamondlike carbon (Ti-Ti(sub x) C(sub y)-DLC) underlayer were produced on AISI 440C stainless steel substrates by the hybrid technique of magnetron sputtering and pulsed-laser deposition. The resultant DLC films were characterized by Raman spectroscopy, scanning electron microscopy, and surface profilometry. Two types of wear experiment were conducted in this investioation: sliding friction experiments and fretting wear experiments. Unidirectional ball-on-disk sliding friction experiments were conducted to examine the wear behavior of an a-DLC/Ti-Ti(sub x) C(sub y)-DLC-coated AISI 440C stainless steel disk in sliding contact with a 6-mm-diameter AISI 440C stainless steel ball in ultrahigh vacuum, dry nitrogen, and humid air. Although the wear rates for both the coating and ball were low in all three environments, the humid air and dry nitrogen caused mild wear with burnishing, in the a-DLC top layer, and the ultrahigh vacuum caused relatively severe wear with brittle fracture in both the a-DLC top layer and the Ti-Ti(sub x) C(sub y)-DLC underlayer. For reference, amorphous hydrogenated carbon (H-DLC) films produced on a-DLC/Ti-Ti(sub x) C(sub y)-DLC nanocomposite coatings by using an ion beam were also examined in the same manner. The H-DLC films markedly reduced friction even in ultrahigh vacuum without sacrificing wear resistance. The H-DLC films behaved much like the a-DLC/Ti-Ti(sub x) C(sub y)-DLC nanocomposite coating in dry nitrogen and humid air, presenting low friction and low wear. Fretting wear experiments were conducted in humid air (approximately 50% relative humidity) at a frequency of 80 Hz and an amplitude of 75 micron on an a

  11. Optimization of pulsed DC PACVD parameters: Toward reducing wear rate of the DLC films

    NASA Astrophysics Data System (ADS)

    Ebrahimi, Mansoureh; Mahboubi, Farzad; Naimi-Jamal, M. Reza

    2016-12-01

    The effect of pulsed direct current (DC) plasma-assisted chemical vapor deposition (PACVD) parameters such as temperature, duty cycle, hydrogen flow, and argon/CH4 flow ratio on the wear behavior and wear durability of the diamond-like carbon (DLC) films was studied by using response surface methodology (RSM). DLC films were deposited on nitrocarburized AISI 4140 steel. Wear rate and wear durability of the DLC films were examined with the pin-on-disk method. Field emission scanning electron microscopy, Raman spectroscopy, and nanoindentation techniques were used for studying wear mechanisms, chemical structure, and hardness of the DLC films. RSM results show that duty cycle is one of the important parameters that affect the wear rate of the DLC samples. The wear rate of the samples deposited with a duty cycle of >75% decreases with an increase in the argon/CH4 ratio. In contrast, for a duty cycle of <65%, the wear rate increases with an increase in the argon/CH4 ratio. The wear durability of the DLC samples increases with an increase in the duty cycle, hydrogen flow, and argon/CH4 flow ratio at the deposition temperature between 85 °C and 110 °C. Oxidation, fatigue, abrasive wear, and graphitization are the wear mechanisms observed on the wear scar of the DLC samples deposited with the optimum deposition conditions.

  12. Imposed Thermal Fatigue and Post-Thermal-Cycle Wear Resistance of Biomimetic Gray Cast Iron by Laser Treatment

    NASA Astrophysics Data System (ADS)

    Sui, Qi; Zhou, Hong; Zhang, Deping; Chen, Zhikai; Zhang, Peng

    2017-08-01

    The present study aims to create coupling biomimetic units on gray cast iron substrate by laser surface treatment (LST). LSTs for single-step (LST1) and two-step (LST2) processes, were carried out on gray cast iron in different media (air and water). Their effects on microstructure, thermal fatigue, and post-thermal-cycle wear (PTW) resistance on the specimens were studied. The tests were carried out to examine the influence of crack-resistance behavior as well as the biomimetic surface on its post-thermal-cycle wear behavior and different units, with different laser treatments for comparison. Results showed that LST2 enhanced the PTW behaviors of gray cast iron, which then led to an increase in its crack resistance. Among the treated cast irons, the one treated by LST2 in air showed the lowest residual stress, due to the positive effect of the lower steepness of the thermal gradient. Moreover, the same specimen showed the best PTW performance, due to its superior crack resistance and higher hardness as a result of it.

  13. Wear resistance of packable resin composites after simulated toothbrushing test.

    PubMed

    Wang, Linda; Garcia, Fernanda Cristina Pimentel; Amarante de Araújo, Paulo; Franco, Eduardo Batista; Mondelli, Rafael Francisco Lia

    2004-01-01

    The purpose of this study was to determine the wear resistance of five different packable composites versus two different composite controls using a laboratory toothbrushing simulation test. Twelve samples measuring 5 mm in diameter and 3 mm thick were prepared from the following resin composites: Packable resin composites SureFil (Dentsply Ind. Com. Ltda, Petrópolis, Rio de Janeiro, Brazil), Alert (Jeneric Pentron Incorporated, Wallingford, CT, USA), Filtek P60 (3M ESPE Dental Products, St. Paul, MN, USA), Prodigy Condensable (sds Kerr, Orange CA, USA), Solitaire (Heraeus Kulzer GmbH, Wehrheim, Germany), and control resin composites Z100 Restorative (3M ESPE) and Silux Plus (3M ESPE). Finishing and polishing were conducted with Sof-Lex disks (3M ESPE), and baseline weight (grams) and surface roughness (measured with Hommel Tester T 1000, Hommelwerke, GmbH, Alte Tuttinger Strebe 20. D-7730 VS-Schwenningen, Germany) were recorded. Specimens were aged for 2 weeks until they reached a weight that remained constant for 5 consecutive days, and then were subjected to 100,000 cycles of brushing (representative of 4.2 yr) using a toothbrushing testing machine. Toothbrush heads with soft bristle tips (Colgate Classic, Colgate-Palmolive Co., Osasco, São Paulo, Brazil) with dentifrice suspension (Colgate MFP, Colgate-Palmolive Co.) in deionized water were used under a 200 g load. Changes in weight and surface roughness were determined after toothbrushing cycles. Significant differences of weight loss and surface roughness were found (paired t-test, p < .05). Weight loss percentage (mean [SD]) ranged from 0.38 to 1.69% (analysis of variance and Tukey's least significant difference, p < .05); the weight loss of the materials ranked from least to most as follows: SureFil (0.38 [0.56]), Alert (0.52 [0.18]), Z100 (1.16 [0.27]), Filtek P60 (1.31 [0.17]), Solitaire (1.51 [0.45]), Prodigy Condensable (1.55 [0.471), and Silux Plus (1.69 [0.66]). Regarding surface roughness, Prodigy

  14. Wear behaviors of pure aluminum and extruded aluminum alloy (AA2024-T4) under variable vertical loads and linear speeds

    NASA Astrophysics Data System (ADS)

    Jung, Jeki; Oak, Jeong-Jung; Kim, Yong-Hwan; Cho, Yi Je; Park, Yong Ho

    2017-11-01

    The aim of this study was to investigate the transition of wear behavior for pure aluminum and extruded aluminum alloy 2024-T4 (AA2024-T4). The wear test was carried using a ball-on-disc wear testing machine at various vertical loads and linear speeds. The transition of wear behaviors was analyzed based on the microstructure, wear tracks, wear cross-section, and wear debris. The critical wear rates for each material are occurred at lower linear speed for each vertical load. The transition of wear behavior was observed in which abrasion wears with the generation of an oxide layer, fracture of oxide layer, adhesion wear, severe adhesion wear, and the generation of seizure occurred in sequence. In case of the pure aluminum, the change of wear debris occurred in the order of blocky, flake, and needle-like debris. Cutting chip, flake-like, and coarse flake-like debris was occurred in sequence for the extruded AA2024-T4. The transition in the wear behavior of extruded AA2024-T4 occurred slower than in pure aluminum.

  15. Final Technical Report: Development of an Abrasion-Resistant Antisoiling Coating for Front-Surface Reflectors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gee, Randy C.

    A high-performance reflective film has been successfully developed for Concentrating Solar Power (CSP) solar concentrators. Anti-soiling properties and abrasion resistance have been incorporated into the reflector to reduce reflector cleaning costs and to enhance durability. This approach has also resulted in higher reflectance and improved specularity. From the outset of this project we focused on the use of established high-volume roll-to-roll manufacturing techniques to achieve low manufacturing costs on a per ubit area basis. Roll-to-roll manufacturng equipment has a high capital cost so there is an entire industry devoted to roll-to-roll “toll” manufacturing, where the equipment is operated “around themore » clock” to produce a multitude of products for a large variety of uses. Using this approach, the reflective film can be manufactured by toll coaters/converters on an as-needed basis.« less

  16. A personal perspective and update on erosive tooth wear - 10 years on: Part 2 - Restorative management.

    PubMed

    Bartlett, D

    2016-08-26

    The management challenge with erosive tooth wear is that the condition involves erosion and contributions from attrition and abrasion, both of which impact on the longevity of restorations. Severe erosive tooth wear results in visibly shorter teeth, exposure of dentine and adaptive changes which complicate restorative management. There is increasing evidence to suggest if the risk factors, such as reducing the frequency of acidic foods and drinks, are reduced the progression of tooth wear slows and follows a normal pattern of wear. But once teeth become shorter patients often seek advice from dentists on restorative intervention. Composite restorations are successful in some patients but they often involve regular maintenance with repairs and rebuilds, which for some patients is unacceptable. Full coverage crowns, although destructive of tooth tissue, remain an option for restorations.

  17. An in situ investigation into the abrasion of eroded dental hard tissues by a whitening dentifrice.

    PubMed

    Turssi, C P; Faraoni, J J; Rodrigues, A L; Serra, M C

    2004-01-01

    This crossover study aimed to investigate abrasion of previously eroded hard dental tissues by a whitening dentifrice compared to a regular dentifrice. After a 3-day lead-in period, 14 volunteers were randomly assigned to use one of the toothpastes while wearing a removable appliance, containing 3 enamel and 3 root dentine slabs on each side. On the first day salivary pellicle was allowed to form. Twice daily for the following 3 days, one side of each appliance was immersed in an acidic carbonated drink ex vivo while the other side remained unexposed. Specimens were then brushed with the allocated dentifrice. After a 3-day washout period, new sets of enamel and dentine slabs were mounted in the appliances and the participants commenced period 2 using the alternative toothpaste. Acid-treated specimens always showed more wear than untreated specimens. The whitening dentifrice did not significantly increase the wear of softened enamel compared with the regular dentifrice. Brushing with the whitening toothpaste led to significantly greater wear of sound enamel and of both eroded and sound dentine than the regular dentifrice. The results suggest that whitening dentifrices may not increase the wear of acid-softened enamel but may have a more deleterious effect on dentine than regular toothpastes.

  18. The influence of dental alloys on three-body wear of human enamel and dentin in an inlay-like situation.

    PubMed

    Graf, K; Johnson, G H; Mehl, A; Rammelsberg, P

    2002-01-01

    This in vitro study evaluated the effect of metal alloys on three-body wear resistance of enamel and dentin, and vice versa. Three-body wear of human enamel, dentin, a soft gold alloy (BiOcclus Inlay), a CoCr alloy (Remanium 2000), a resin cement (Variolink II) and a zinc oxide phosphate cement (Harvard) was investigated using the ACTA-machine. Sample chambers of eight sample wheels were prepared with pure materials or combinations of human tooth substance, alloys and cement, simulating an inlay-like situation. After 100,000 and 200,000 cycles in a millet suspension with a spring force of 20 N, the amount of abraded material was profilometrically measured and evaluated by 3D surface data analysis. After 200,000 cycles, the materials demonstrated a mean loss of 0.41 microm for CoCr, 51 microm for gold, 57 microm for enamel, 164 microm for dentin, 79 microm for Variolink and 369 microm for Harvard. Using ANOVA and the Games-Howell-test, resin cement, enamel and gold were a subset not shown to differ, as was zinc phosphate cement and dentin. CoCr demonstrated the least wear and differed significantly from all materials. Enamel wear was significantly reduced in mixed chambers with CoCr, and gold after 200,000 cycles compared to enamel in pure chambers. In summary, a soft gold alloy can be recommended for inlays when considering three-body abrasion since the wear rate of the "soft" gold alloy corresponded to that of human enamel.

  19. Experience with wear-resistant materials at the Homer City Coal Cleaning Plant

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Williams, W.R.

    1984-10-01

    The Homer City Coal Cleaning Plant is a multistream, dual-circuit facility with a total capacity of 1.22 x 10/sup 6/ Kg/hr (1200 TPH) raw feed and serves the three generating units of the Pennsylvania Electric Company's Homer City Generating Station. The complicated multi-cleaning circuit design requires considerably more power and piping (10.6 km/35,000 ft of plus 5 cm/2 in. process piping) than a more conventional plant of the same capacity. Coupled with the maintenance intensive aspects of the plant is the requirement to have a high availability due to the mine mouth-to-cleaning plant-to-generating station philosophy under which it operates. Thesemore » factors required a dedicated effort to improve equipment wear characteristics. Experiences in the use of a variety of wear and corrosion resistant materials at the Homer City Coal Cleaning Plant are described.« less

  20. Do Abrasives Play a Role in Toothpaste Efficacy against Erosion/Abrasion?

    PubMed

    Ganss, Carolina; Möllers, Maike; Schlueter, Nadine

    2017-01-01

    Abrasives may counteract the efficacy of anti-erosion toothpastes either due to physical effects or due to interaction with active agents. This study aimed to investigate whether the amount of abrasives is a determinant for the efficacy of Sn2+-containing toothpastes with or without chitosan additive. Enamel samples were eroded (0.50 wt% citric acid, pH 2.5; 6 × 2 min/day) on a shaking desk - 30/min in experiment 1 (E1) and 35/min in experiments 2 (E2) and 3 (E3) - and immersed in toothpaste slurries (2 × 2 min). Half of the samples were additionally brushed (15 s, load 200 g) within the immersion time. The toothpastes contained 0, 5, 10, 15, and 20% silica. In E1 and E2 the active ingredients were F- (700 ppm as amine fluoride, 700 ppm as NaF) and Sn2+ (3,500 ppm as SnCl2); in E3 chitosan (0.5%) was additionally added. The placebo contained 20% silica. Tissue loss was determined profilometrically. In E1, slurries completely inhibited tissue loss; distinct surface deposits occurred. With brushing, tissue loss significantly increased up to an abrasive content of 10%, but decreased significantly with higher amounts; 20% silica revealed similar values as the abrasive-free formulation. In E2, all slurries inhibited tissue loss distinctly irrespective of the amounts of abrasives. With brushing, a similar trend as in E1 was observed but with much less efficacy. The chitosan-containing formulations in E3 were much more effective; similar results as in E1 were found. In conclusion, the amount of abrasives had no effect when toothpastes were applied as slurries, but played an important role with brushing. © 2016 S. Karger AG, Basel.

  1. Low Temperature Processing of Boron Carbide Cement Composite for Tough, Wear Resistant Structures

    DTIC Science & Technology

    1997-12-15

    TITLE AND SUBTITLE Low Temperature Processing of Boron Carbide Cement Composite for Tough, Wear Resistant Structures 6. AUTHOR(S) Kristen J. Law...project has developed a low temperature polymer ceramic composite consisting of boron carbide layers bonded by cement, laminated with polymer...composite have been shown to compare favorably to those of partially sintered boron carbide. Applications for this material have been identified in

  2. Development and Application of High Performance Quenched and Tempered Wear Resistant Steels in Material Handling and Construction Machinery

    NASA Astrophysics Data System (ADS)

    Su, Fenwei; Sidiras, Evangelos

    The demand for more sustainable development promotes the need for components and steel structures with a longer useful life and better performance. Upgrade of wear steel plate used in key industry segments such as mining, recycling and road building results in the stable growth of global market with high quality grade Q&T wear plates (Hardness HBW≥400, and Yield strength ≥690 Mpa). SSAB has now expanded its wear steel product range by both thicker and thinner Q&T plate to meet the needs of the market, and can offer wear plates from 0.7 mm to 160 mm. The continuous research and development is being done to offer even thicker plates. This article introduces the performance and advantages of high quality grade Q&T wear resistant steel products (plate, strip, tube and round bars) produced in SSAB, and also describes typical applications in some industrial segments such as material handling and construction machinery.

  3. Friction, Wear, and Surface Damage of Metals as Affected by Solid Surface Films

    NASA Technical Reports Server (NTRS)

    Bisson, Edmond E; Johnson, Robert L; Swikert, Max A; Godfrey, Douglas

    1956-01-01

    As predicted by friction theory, experiments showed that friction and surface damage of metals can be reduced by solid surface films. The ability of materials to form surface films that prevent welding was a very important factor in wear of dry and boundary lubricated surfaces. Films of graphitic carbon on cast irons, nio on nickel alloys, and feo and fe sub 3 o sub 4 on ferrous materials were found to be beneficial. Abrasive films such as fe sub 2 o sub 3 or moo sub 3 were definitely detrimental. It appears that the importance of oxide films to friction and wear processes has not been fully appreciated.

  4. Experimental research on microhardness and wear resistances of pure Cu subjected to surface dynamic plastic deformation by ultrasonic impact

    NASA Astrophysics Data System (ADS)

    Chen, Zhaoxia; He, Yangming

    2018-04-01

    Dynamic plastic deformation (DPD) has been induced in the surface of pure Cu by ultrasonic impact treating (UIT) with the varied impact current and coverage percentage. The microstructures of the treated surface were analyzed by a scanning electron microscope (SEM). And the wear resistance of pure Cu was experimentally researched both with the treated and untreated specimens. The effect of DPD on the hardness was also investigated using microhardness tester. The results show that the grains on the top surfaces of pure Cu are highly refined. The maximum depth of the plastic deformation layer is approximately 1400 µm. The larger the current and coverage percentage, the greater of the microhardness and wear resistance the treated surface layer of pure Cu will be. When the impact current is 2 A and coverage percentage is 300%, the microhardness and wear resistance of the treated sample is about 276.1% and 68.8% higher than that of the untreated specimen, respectively. But the properties of the treated sample deteriorate when the UIT current is 3 A and the coverage percentage is 300% because of the formation of a new phase forms in the treated surface.

  5. Surface Modifications for Improved Wear Performance in Artificial Joints: A Review

    NASA Astrophysics Data System (ADS)

    Sullivan, Stacey J. L.; Topoleski, L. D. Timmie

    2015-11-01

    Artificial joint replacement is one of the most successful treatments for arthritis. Excellent wear and corrosion resistance, together with high strength and fracture toughness, are fundamental requirements for implant materials. Wear and/or corrosion of the materials used in artificial joints may lead to implant failure. Therefore, hard and wear-resistant materials, like cobalt-chromium-molybdenum and ceramic, are currently used as bearing surfaces. However, even using such hard materials, wear and/or corrosion related failure of artificial joints remains a central concern. One primary goal in orthopedic biomaterials research is to create more wear-resistant surfaces. Different technologies have been used to create new surfaces, or to modify existing surfaces, to prevent wear. It is the intent of this overview first to provide a summary of materials currently used as bearing surfaces in artificial joints, their functions, and their contributions to device longevity. Then, we will discuss advancements in modifying those bearing surfaces to produce more wear-resistant artificial joints.

  6. Tribology in mineral extraction: War on wear

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Not Available

    1984-01-01

    Mineral extraction, whether coal or ores, and the machinery employed are subjected to very hostile conditions of operation. These conditions cause great damage to interacting surfaces in relative motion. Much valuable time is lost because of abrasion and wear and further, often unnecessary, costs are incurred through avoidable maintenance and repair. Yet tribological solution to this pointless waste of resources, energy and production are often already well known in universities, research laboratories and in pockets within the industry. The papers presented at the IMechE conference identify the problems and demonstrate solutions. This book compiles the papers presented in this conference.more » The contents of this book include: Some practical examples of reducing the effect of tribological phenomena produced in transporting solids; wear of digger teeth; factors influencing the choice of lubricants for draglines; filtration of oils; tribology and slipper pad braking of rail mounted vehicles in coal mines; and failure analysis aided by fracture mechanics.« less

  7. Nanostructured and Conventional Cr2O3, TiO2, and TiO2-Cr2O3 Thermal-Sprayed Coatings for Metal-Seated Ball Valve Applications in Hydrometallurgy

    NASA Astrophysics Data System (ADS)

    Vernhes, Luc; Bekins, Craig; Lourdel, Nicolas; Poirier, Dominique; Lima, Rogerio S.; Li, Duanjie; Klemberg-Sapieha, Jolanta E.

    2016-06-01

    A detailed characterization project was undertaken by Velan, an international industrial valve designer and manufacturer, in collaboration with the National Research Council of Canada, Boucherville, and Polytechnique Montréal. The purpose was to assess the mechanical and tribological resistances of promising ceramic coatings for hydrometallurgy applications, including a novel n-TiO2-Cr2O3 blend. Hardness and shear strength were determined using microhardness indentation testers and universal tensile testing equipment. Wear resistance of the coatings under sliding wear, abrasion, and galling conditions were measured by standard pin-on-disk tests, abrasion tests, and custom-designed galling tests. The main result is that the synergy between Cr2O3 and n-TiO2 produced abrasion performance exceeding that of these materials alone. Also, an optimized balance between the hard and brittle Cr2O3 phases and the soft and ductile n-TiO2 phases resulted in higher abrasion, sliding, and galling resistance. The novel n-TiO2-Cr2O3 blend is therefore considered as a promising evolution of the current TiO2-Cr2O3 blend.

  8. Effect of Friction-Induced Deformation on the Structure, Microhardness, and Wear Resistance of Austenitic Chromium—Nickel Stainless Steel Subjected to Subsequent Oxidation

    NASA Astrophysics Data System (ADS)

    Korshunov, L. G.; Chernenko, N. L.

    2016-03-01

    The effect of plastic deformation that occurs in the zone of the sliding friction contact on structural transformations in the 12Kh18N9T austenitic steel subjected to subsequent 1-h oxidation in air at temperatures of 300-800°C, as well as on its wear resistance, has been studied. It has been shown that severe deformation induced by dry sliding friction produces the two-phase nanocrystalline γ + α structure in the surface layer of the steel ~10 μm thick. This structure has the microhardness of 5.2 GPa. Subsequent oxidation of steel at temperatures of 300-500°C leads to an additional increase in the microhardness of its deformed surface layer to the value of 7.0 GPa. This is due to the active saturation of the austenite and the strain-assisted martensite (α') with the oxygen atoms, which diffuse deep into the metal over the boundaries of the γ and α' nanocrystals with an increased rate. The concentration of oxygen in the surface layer of the steel and in wear products reaches 8 wt %. The atoms of the dissolved oxygen efficiently pin dislocations in the γ and α' phases, which enhances the strength and wear resistance of the surface of the 12Kh18N9T steel. The oxidation of steel at temperatures of 550-800°C under a light normal load (98 N) results in the formation of a large number of Fe3O4 (magnetite) nanoparticles, which increase the resistance of the steel to thermal softening and its wear resistance during dry sliding friction in a pair with 40Kh13 steel. Under a heavy normal load (196 N), the toughness of 12Kh18N9T steel and, therefore, the wear resistance of its surface layer decrease due to the presence of the brittle oxide phase.

  9. Friction and Wear Behavior of Plasma-Sprayed Al2O3-13 wt.%TiO2 Coatings Under the Lubrication of Liquid Paraffin

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaoqin; An, Yulong; Hou, Guoliang; Zhou, Huidi; Chen, Jianmin

    2014-04-01

    Two types of ceramic composite coatings (denoted as N-AT13 coating and M-AT13 coating) were fabricated on 1Cr18Ni9Ti stainless steel substrate from ultra-fine and coarse Al2O3-13%TiO2 feedstocks by air plasma spraying. The friction and wear behavior of as-prepared coatings sliding against Al2O3 and stainless steel balls under the lubrication of liquid paraffin was evaluated with an SRV friction and wear tester (Optimol, Germany). The fractured and worn surfaces of the coatings were observed using a scanning electron microscope and a field-emission scanning electron microscope; and the wear mechanisms of the coatings were discussed based on scanning electron microscopic analysis and energy dispersive spectrometric analysis. Results show that N-AT13 coating possesses a unique microstructure and strong inter-splat bonding, thereby showing increased microhardness and bonding strength as well as much better friction-reduction and wear resistance than M-AT13 coating. Moreover, there exist differences in the wear mechanisms of N-AT13 and M-AT13 coatings which slide against ceramic and stainless steel balls under the lubrication of liquid paraffin. Namely, with the increase of normal load, the burnishing of N-AT13 coating coupled with Al2O3 ball is gradually transformed to grain-abrasion and deformation, while M-AT13 coating is dominated by grain-pullout and brittle fracture in the whole range of tested normal load.

  10. Effect of in-situ TiC particulate on the wear resistance of spray-deposited 7075 Al matrix composite

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang Feng; Liu Huimin; Yang Bin

    2005-05-15

    TiC reinforced 7075 Al matrix composites have been fabricated by a melt in-situ reaction spray deposition. The microstructures of spray-deposited alloys were studied using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The dry sliding wear behavior of the alloys was investigated using a pin-on-disc machine under four loads, namely 8.9, 17.8, 26.7 and 35.6 N. It has been found that the wear behavior of the alloys was dependent on the TiC content in the microstructure and the applied load. At a lower load (8.9 N), with increasing TiC content, the wear rate of the alloy was decreased. At amore » higher loads (26.7, 35.6 N), a spray-deposited 7075 Al alloy exhibited superior wear resistance to the 7075/TiC composites.« less

  11. Evaluation of titanium carbide metal matrix composites deposited via laser cladding

    NASA Astrophysics Data System (ADS)

    Cavanaugh, Daniel Thomas

    Metal matrix composites have been widely studied in terms of abrasion resistance, but a particular material system may behave differently as particle size, morphology, composition, and distribution of the hardening phase varies. The purpose of this thesis was to understand the mechanical and microstructural effects of combining titanium carbide with 431 series stainless steel to create a unique composite via laser cladding, particularly regarding wear properties. The most predominant effect in increasing abrasion resistance, measured via ASTM G65, was confirmed to be volume fraction of titanium carbide addition. Macrohardness was directly proportional to the amount of carbide, though there was an overall reduction in individual particle microhardness after cladding. The reduction in particle hardness was obscured by the effect of volume fraction carbide and did not substantially contribute to the wear resistance changes. A model evaluating effective mean free path of the titanium carbide particles was created and correlated to the measured data. The model proved successful in linking theoretical mean free path to overall abrasion resistance. The effects of the titanium carbide particle distributions were limited, while differences in particle size were noticeable. The mean free path model did not correlate well with the particle size, but it was shown that the fine carbides were completely removed by the coarse abrasive particles in the ASTM G65 test. The particle morphology showed indications of influencing the wear mode, but no statistical reduction was observed in the volume loss figures. Future studies may more specifically focus on particle morphology or compositional effects of the carbide particles.

  12. Preparation and Wear Resistance of Aluminum Composites Reinforced with In Situ Formed TiO/Al2O3

    NASA Astrophysics Data System (ADS)

    Qin, Q. D.; Huang, B. W.; Li, W.; Zeng, Z. Y.

    2016-05-01

    An in situ TiO/Al2O3-reinforced Al composite is successfully prepared using a powder metallurgy route by the reaction of Ti2CO and Al powder. The Ti2CO powder is produced by carrying out a carbothermic reduction of titanium dioxide at 1000 °C. XRD results show that the final product is composed of Al, TiO, Al2O3, and Al3Ti. Morphology examination of the composite reveals the presence of bigger blocks of TiO and fine particles of Al2O3 and the volume fraction of reinforcement is found to range between 18 and 55%. As the volume fraction of the reinforced materials approaches 50%, the particles start to agglomerate. Dry sliding wear tests conducted using a conventional pin-on-disk testing machine show that the wear resistance of the composite is higher than that of the pure aluminum ingot. The wear rate of the composite increases almost linearly with the increase in the wear distance. The sliding wear test shows that as the volume fraction of the reinforced phase increases, the coefficient of friction decreases. The wear mechanism is also discussed.

  13. Wear studies on plasma-sprayed Al2O3 and 8mole% of Yttrium-stabilized ZrO2 composite coating on biomedical Ti-6Al-4V alloy for orthopedic joint application

    PubMed Central

    Ganapathy, Perumal; Manivasagam, Geetha; Rajamanickam, Asokamani; Natarajan, Alagumurthi

    2015-01-01

    This paper presents the wear characteristics of the composite ceramic coating made with Al2O3-40wt%8YSZ on the biomedical grade Ti-6Al-4V alloy (grade 5) used for total joint prosthetic components, with the aim of improving their tribological behavior. The coatings were deposited using a plasma spraying technique, and optimization of plasma parameters was performed using response surface methodology to obtain dense coating. The tribological behaviors of the coated and uncoated substrates were evaluated using a ball-on-plate sliding wear tester at 37°C in simulated body-fluid conditions. The microstructure of both the titanium alloy and coated specimen were examined using an optical microscope and scanning electron microscope. The hardness of the plasma-sprayed alumina–zirconia composite coatings was 2.5 times higher than that of the Ti-6Al-4V alloy, while the wear rate of Ti-6Al-4V alloy was 253 times higher than that of the composite-coated Ti-6Al-4V alloy. The superior wear resistance of the alumina–zirconia coated alloy is attributed to its enhanced hardness and intersplat bonding strength. Wear-track examination showed that the predominant wear mechanism of Ti-6Al-4V alloy was abrasive and adhesive wear, whereas, in the case of alumina–zirconia composite coated alloy, the wear was dominated by microchipping and microcracking. PMID:26491323

  14. Tribo-Mechanical Properties of HVOF Deposited Fe3Al Coatings Reinforced with TiB2 Particles for Wear-Resistant Applications

    PubMed Central

    Amiriyan, Mahdi; Blais, Carl; Savoie, Sylvio; Schulz, Robert; Gariépy, Mario; Alamdari, Houshang

    2016-01-01

    This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF) technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load. This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2

  15. Experimental analysis of pressure controlled atomization process (PCAP) coatings for replacement of hard chromium plating

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tierney, J.C.; Glovan, R.J.; Witt, S.J.

    1995-12-31

    A four-phase experimental design was utilized to evaluate the abrasive wear and corrosion protection characteristics of VERSAlloy 50 coatings applied to AISI 4130 steel sheet. The coatings were applied with the Pressure Controlled Atomization Process (PCAP), a new thermal spray process being developed for the United States Air Force to replace hard chromium plating. Phase 1 of the design consisted of an evaluation of deposit profiles that were sprayed at five different standoff distances. Profile measurements yielded standard deviations ({sigma}) of the plume at each of the spray distances. Phase 2 consisted of a completely randomized series of eight spraymore » tests in which the track gap or distance between consecutive spray passes was varied by amounts of 0.5{sigma}, 1{sigma}, 2{sigma}, and 3{sigma}. The sprayed test coupons were then evaluated for corrosion protection, abrasive wear resistance, microhardness, and porosity. Results from Phase 2 were used to determine the best track gap or overlap for Phase 3 and Phase 4 testing. Phase 3 consisted of 22-run central composite design. The test coupons were evaluated the same as in Phase 2. Statistical analysis of Phase 3 data revealed that the optimal system operating parameters produced coatings that would either provide superior corrosion protection or resistance to abrasive wear. Phase 4 consisted of four spray tests to validate the results obtained in Phase 3. Phase 4 test coupons were again evaluated with the same analysis as in Phases 2 and 3. The validation tests indicated that PCAP system operating parameters could be controlled to produce VERSAlloy 50 coatings with superior corrosion protection or resistance to abrasive wear.« less

  16. RETRACTED: Chemical densification of plasma sprayed yttria stabilized zirconia (YSZ) coatings for high temperature wear and corrosion resistance

    NASA Astrophysics Data System (ADS)

    Ye, Yaping; Fehr, Karl Thomas; Faulstich, Martin; Wolf, Gerhard

    2012-12-01

    Plasma-sprayed yttria stabilized zirconia (YSZ) ceramic coatings have been widely used as wear- and corrosion-resistant coatings in high temperature applications and an aggressive environment due to their high hardness, wear resistance, heat and chemical resistance, and low thermal conductivity. The highly porous structure of plasma-sprayed ceramic coatings and their poor adhesion to the substrate usually lead to the coating degradation and failure. In this study, a two-layer system consisting of atmospheric plasma-sprayed 8 wt.% yttria-stabilized zirconia (8YSZ) and Ni-based alloy coatings was post-treated by means of a novel chemical sealing process at moderate temperatures of 600-800 °C. Microstructure characteristics of the YSZ coatings were studied using an electron probe micro-analyzer (EPMA). Results revealed that the ceramic top coat was densified by the precipitated zirconia in the open pores. Therefore, the sealed YSZ coatings exhibit reduced porosity, higher hardness and a better adhesion onto the bond coat. The mechanisms for the sealing process were also proposed.

  17. Evolution and diagnostic utility of aeolian rat-tails: A new type of abrasion feature on Earth and Mars

    NASA Astrophysics Data System (ADS)

    Favaro, Elena A.; Hugenholtz, Christopher H.; Barchyn, Thomas E.

    2017-10-01

    Aeolian rat-tails (ARTs) are a previously undocumented, regionally-ubiquitous aeolian abrasion feature observed on matrix-supported ignimbrite surfaces in the Puna Plateau of Northwest Argentina. ARTs consist of an abrasion-resistant lithic clast projecting above the surface with a lee tail or 'keel' in the more erodible matrix. Size is controlled by the dimensions of the windward lithic clast, ranging from centimetre to meter scale; spatial density varies with clast content, which may reflect variations in ignimbrite facies. Field observations suggest ARTs follow a definable evolutionary sequence. First, an abrasion-resistant lithic clast contained within the ignimbrite is exposed to abrasion at the surface. Impacts from abrading particles erode the softer ignimbrite matrix adjacent to the clast. The clast shelters the leeward surface under a unimodal abrasion direction, creating a tail that tapers downwind and elongates as the clast emerges. Clasts become dislodged from the matrix as the surrounding surface erodes, ultimately destroying the feature if the clast is small enough to be mobilized directly by wind or impacting particles. This evolutionary sequence explains the morphology of ARTs and the presence of loose clasts on the ignimbrite surface, which contributes to the development of other landforms in the region, such as periodic bedrock ridges, yardangs, and megaripples. Satellite and rover images suggest similar features also exist on Mars. Because the formation and preservation of ARTs is contingent on unimodal abrasion direction, their orientation can be used as an indicator of long-term aeolian sediment transport direction.

  18. Tribological Behavior of Al-Cr Coating Obtained by Dgpsm and IIP Composite Technology

    NASA Astrophysics Data System (ADS)

    Luo, Xixi; Yao, Zhengjun; Zhang, Pingze; Zhou, Keyin; Chen, Yu; Tao, Xuewei

    An Al-Cr composite alloyed layer composed of an Al enriched layer, a Cr enriched layer and a transition layer from the surface to the bulk along the cross-section was deposited on a 45# steel substrate by composite technology, where Cr was deposited using double glow plasma surface metallurgy (DGPSM), and Al was then implanted by ion implantation (IIP) to achieve higher micro-hardness and excellent abrasive resistance. The composite alloyed layer is approximately 5μm, and as metallurgical adherence to the substrate. The phases are Al8Cr5, Fe2AlCr, Cr23C6, Cr (Al) and Fe (Cr, Al) solid solution. The wear resistance tests were performed under various rotational speed (i.e. 280, 560 and 840r/min) with silicon nitride balls as the counterface material at ambient temperature. The Al-Cr composite alloyed layer exhibits excellent wear resistance when the speed is 280r/min with a friction coefficient as low as 0.3, which is attributed to Al8Cr5 in the Al implanted layer that withstands abrasive wear. Better wear resistance (friction coefficient: 0.254) at 560r/min is resulted from the formation of a high micro-hardness zone, and an oxidation layer with lubrication capacity. In addition, the composite alloyed layer suffers severe oxidative wear and adhesive wear at 840r/min due to the increment of the frictional heating. When compared to the 45# steel substrate, the enhanced wear resistance of the Al-Cr composite alloyed layer demonstrates the viable method developed in this work.

  19. Physics of loose abrasive microgrinding.

    PubMed

    Golini, D; Jacobs, S D

    1991-07-01

    This study examined the physics of loose abrasive microgrinding (grinding with micron and submicron sized abrasives). More specifically, it focused on the transition from brittle to ductile mode grinding which occurs in this region of abrasive sizes. Process dependency on slurry chemistry was the primary area of emphasis and was studied for diamond abrasives varying in size from 3.0 to 0.75 microm on both ULE and Zerodur, with emphasis on ULE. Ductile mode grinding was achieved with smaller abrasives, as expected, however two significant discoveries were made. The first observation was that by simply changing slurry chemistry, it was possible to induce the transition from brittle fracture to ductile mode grinding in ULE. This transition point could be intentionally moved about for diamonds 3.0-0.75 microm in diameter. For any given abrasive size within these limits, either brittle fracture or ductile removal may be achieved, depending on the slurry used to suspend the diamonds. Several slurries were studied, including water, a series of homologous n-alcohols, and other solvents chosen for properties varying from molecular size to dielectric constant and zeta potential. The study revealed that this slurry dependency is primarily a Rebinder effect. The second finding was that a tremendous amount of surface stress is introduced in loose abrasive ductile mode grinding. This stress was observed when the Twyman Effect in ULE plates increased by a factor of 4 in the transition from the brittle to the ductile mode. An assessment of the cause of this stress is discussed.

  20. High wear resistance of femoral components coated with titanium nitride: a retrieval analysis.

    PubMed

    Fabry, Christian; Zietz, Carmen; Baumann, Axel; Ehall, Reinhard; Bader, Rainer

    2017-05-20

    The objective of this study was to evaluate the in vivo wear resistance of cobalt-chromium femoral components coated with titanium nitride (TiN). Our null hypothesis was that the surface damage and the thickness of the TiN coating do not correlate with the time in vivo. Twenty-five TiN-coated bicondylar femoral retrievals with a mean implantation period of 30.7 ± 11.7 months were subjected to an objective surface damage analysis with a semi-quantitative assessment method. A visual examination of scratches, indentations, notches and coating breakthroughs of the surfaces was performed. The roughness and the coating thickness of the TiN coating were evaluated in the main articulation regions. Narrow scratches and indentations in the range of low flexion angles on the retrieval surfaces were the most common modes of damage. There was no evidence of delamination on the articulation surface but rather at the bottom of isolated severe indentations or notches. An analysis of three retrievals revealed a coating breakthrough in the patellofemoral joint region, resulting from patella maltracking and a dislocation. The arithmetical mean roughness of the TiN surface slightly increased with the implantation period. In contrast, the maximum peak height of the roughness profile was reduced at the condyles of the retrieved components in comparison with new, unused surfaces. No significant association between the coating thickness and implantation period was determined. Moreover, the measured values were retained in the range of the initial coating thickness even after several years of in vivo service. As was demonstrated by the results of this study, the surface damage to the TiN coating did not deteriorate with the implantation period. The calculated damage scores and the measured coating thickness in particular both confirmed that the TiN coating provides low wear rates. Our findings support the use of wear-resistant TiN-coated components in total knee arthroplasty with the

  1. Preventive Effect of CPP-ACPF Paste and Fluoride Toothpastes Against Erosion and Erosion Plus Abrasion 
In Vitro - A 3D Profilometric Analysis.

    PubMed

    Soares, Genaina Guimarães; Magalhães, Pâmela Amorim; Fonseca, Ana Beatriz Monteiro; Tostes, Monica Almeida; Silva, Eduardo Moreira da; Coutinho, Thereza Christina Lopes

    To evaluate the effect of CPP-ACPF paste and fluoride toothpastes on enamel subjected to erosion and erosion plus abrasion in vitro. A total of 220 human enamel blocks were divided into eleven groups (n = 20): CPP-ACPF paste (MPP), potassium nitrate/sodium fluoride toothpaste (PE), sodium fluoride toothpaste (FD), fluoride-free toothpaste (SO) and control (erosion only with no paste or toothpastes; CO) according to the experimental design: erosion or erosion plus abrasion immediately after erosion (ERO+I-ABR) or 30 min after erosion (ERO+30min-ABR). For 5 days, the specimens were subjected to: (1) erosive challenge (EC) (cola drink, 4 x 5 min/day), topical application of the undiluted paste or diluted toothpastes (1:2 w/w) (4 x 1 min/ day) plus 1 h in artificial saliva (AS) between cycles and overnight; or (2) EC plus abrasion (4 x /60 s/day) performed with the diluted toothpastes (no MMP) plus 1 h in AS between cycles and overnight. Erosion depth was quantified through a 3D profilometer. Data were analysed using Kruskal-Wallis, Mann-Whitney and Wilcoxon tests (p = 0.05). CPP-ACPF paste and NaF toothpaste showed lowest enamel wear among groups and reduced tissue loss by 89% in erosion challenge. Abrasion led to higher enamel wear than erosion only (p = 0.030). ERO+30min-ABR had no protective effect when compared to ERO+I-ABR (p > 0.05). A high frequency of CPP-ACPF paste application (4x daily) is effective in reducing the effects of erosion. A waiting period before performing toothbrushing does not protect enamel against erosion regardless the composition of the toothpastes.

  2. In vitro wear of various orthotic device materials.

    PubMed

    Casey, Jeffery; Dunn, William J; Wright, Edward

    2003-11-01

    Orthotic devices are advocated to decrease occlusal attrition caused by bruxism but tend to wear with time. This study investigated the wear rate of various materials used to fabricate orthotic devices. Five experimental groups (n=8) were studied: Splint Biocryl autopolymerized (SBA), Splint Biocryl autopolymerized plus additional heat and pressure (SBHP), Forestacryl autopolymerized (FA), Forestacryl autopolymerized plus additional heat and pressure (FHP), and Quick Splint 15-minute (QS), light-polymerized composite. Specimens were mounted to the base of a universal testing machine. A wear device using steatite balls and a load of 9.1 kg was positioned against the specimens, submerged in a 37 degrees C water bath and subjected to 2500 reciprocal cycles. Wear, in micrometers, was calculated as the maximum peak to valley measurement (Ry) using profilometry. Data were subjected to analysis of variance (ANOVA) and Tukey's HSD (alpha=.05). Mean acrylic wear in micrometers was as follows: FA 6.8 +/-3.0; FHP 7.1 +/- 1.8; SBA 20.4 +/- 5.6; SBHP 23.7 +/- 7.8; and QS 23.8 +/- 6.9. One-way ANOVA detected significant differences between groups (P<.001); the Tukey honestly significant difference test determined that FA and FHP specimens were significantly more resistant to wear than all other specimens (P=.007). Differences in in vitro wear resistance among various orthotic device materials exist. The in vitro wear resistance among other autopolymerizing materials appears to be related to proprietary differences.

  3. Friction and wear behaviour of plasma sprayed Cr2O3-TiO2 coating

    NASA Astrophysics Data System (ADS)

    Bagde, Pranay; Sapate, S. G.; Khatirkar, R. K.; Vashishtha, Nitesh; Tailor, Satish

    2018-02-01

    Cr2O3-25TiO2 coating was deposited by atmospheric plasma spray (APS) coating technique. Effect of load (5-30 N) and sliding velocity (0.25, 0.75 m s-1) on friction coefficient and abrasive wear behaviour of the Cr2O3-25TiO2 coating was studied. Mechanical and microstructural characterization of the Cr2O3-25TiO2 coating was carried out. With an increase in sliding velocity, abrasive wear rate and friction coefficient (COF) decreased while wear rate and friction coefficient showed an increasing trend with the load. The worn out surfaces were analyzed by SEM, EDS and XRD. At lower sliding velocity, XRD analysis revealed peaks of Ti2O3, Ti3O5, CrO2 and CrO3. In addition, peak of Ti4O7 was also detected at higher sliding velocity and at 30 N load. At higher sliding velocity medium to severe tribo oxidation was observed. XPS analysis of worn surfaces at both the sliding velocities, showed surface film of oxides of titanium and chromium along with Cr(OH)3. Magneli phase titanium oxides with sub stoichiometric composition, along with surface films of chromium oxides and hydroxides altered the friction and wear behaviour of the coating. The decrease in friction coefficient with an increase in sliding velocity was attributed to tribo oxides and tribochemical reaction films having lower shear strength with good lubricating properties. The mechanism of material removal involved plastic deformation at lower load whereas inter-granular and trans-granular fracture, delamination cracking and splat fracture was observed with an increase load from 10 N to 30 N.

  4. An epidemiologic approach to toothbrushing and dental abrasion.

    PubMed

    Bergström, J; Lavstedt, S

    1979-02-01

    Abrasion lesions were recorded in 818 individuals representing the adult population of 430,000 residents of the Stockholm region, Sweden. The subjects were asked about toothbrushing habits, toothbrush quality and dentifrice usage; these factors were related to abrasion criteria. Abrasion was prevalent in 30% and wedge-like or deep depressions were observed in 12%. The relationship between abrasion and toothbrushing was evident, the prevalence and severity of abrasion being correlated to toothbrushing consumption. The importance of the toothbrushing technique for the development of abrasion lesions was elucidated. Horizontal brushing technique was strongly correlated to abrasion. It was demonstrated by treating the data with the statistical AID analysis that toothbrushing factors related to the individual (brushing frequency and brushing technique) exert a greater influence than material-oriented toothbrushing factor such as dentifrice abrasivity and bristle stiffness.

  5. The effects of ultrasonic nanocrystal surface modification temperature on the mechanical properties and fretting wear resistance of Inconel 690 alloy

    NASA Astrophysics Data System (ADS)

    Amanov, A.; Umarov, R.

    2018-05-01

    In this study, a combination of local heat treatment (LHT) with (w/) and without (w/o) ultrasonic nanocrystal surface modification (UNSM) technique was applied to Inconel 690 alloy at room and high temperatures (RT and HT). The main purpose of this study is to investigate the influence of LHT w/ and w/o UNSM processing on the mechanical and fretting wear mitigation of Inconel 690 alloy. The surface roughness of the specimens was increased with increasing the LHT temperature w/ and w/o UNSM from RT to HT at 700 °C, while the surface hardness of the RT and HT at 300 °C specimens was increased and softening occurred at HT at 700 °C. The mechanical properties of the specimens were investigated using a tensile stress test. It was found that the stress-strain curve of the UNSM-treated at RT exhibited better mechanical characteristics in comparison with the as-received one. Moreover, the specimens treated at HT at 300 and 700 °C exhibited better results in terms of strain, but there was no significant difference in stress. The UNSM treated specimens at HT of 300 °C had better results in comparison with other specimens. In addition, the fretting wear resistance of those specimens was assessed using a ball-on-disk fretting wear tester at temperatures of 25 and 80 °C. The fretting wear resistance of Inconel 690 alloy was also increased by the combination of LHT + UNSM processing, which may be attributed to the increase in mechanical properties, increase in surface roughness, induced compressive residual stress and the presence of a nanostructured surface layer. Hence, Inconel 690 alloy with the increased mechanical properties and fretting wear resistance by the combination of LHT + UNSM processing could be beneficial for nuclear applications.

  6. Influence of load and sliding velocity on wear resistance of solid-lubricant composites of ultra-high molecular weight polyethylene

    NASA Astrophysics Data System (ADS)

    Panin, S. V.; Kornienko, L. A.; Buslovich, D. G.; Alexenko, V. O.; Ivanova, L. R.

    2017-12-01

    To determine the limits of the operation loading intervals appropriate for the use of solid lubricant UHMWPE composites in tribounits for mechanical engineering and medicine, the tribotechnical properties of UHMWPE blends with the optimum solid lubricant filler content (polytetrafluoroethylene, calcium stearate, molybdenum disulfide, colloidal graphite, boron nitride) are studied under dry sliding friction at different velocities (V = 0.3 and 0.5 m/s) and loads (P = 60 and 140 N). It is shown that the wear resistance of solid lubricant UHMWPE composites at moderate sliding velocities (V = 0.3 m/s) and loads (P = 60 N) increases 2-3 times in comparison with pure UHMWPE, while at high load P = 140 N wear resistance of both neat UHMWPE and its composites is reduced almost twice. At high sliding velocities and loads (up to P = 140 N), multiple increasing of the wear of pure UHMWPE and its composites takes place (by the factor of 5 to 10). The operational conditions of UHMWPE composites in tribounits in engineering and medicine are discussed.

  7. Comparative analysis of coarse surfacing aggregate using Micro-Deval, L.A. Abrasion and Sodium Sulfate Soundness Tests.

    DOT National Transportation Integrated Search

    2007-01-01

    "Aggregates used in the construction of roads must be durable, abrasion resistant, and freeze-thaw resistant in : order to perform well in pavement or as base course. The objective of this study was to investigate whether the : Micro-Deval test will ...

  8. Effect of Cu content on wear resistance and mechanical behavior of Ti-Cu binary alloys

    NASA Astrophysics Data System (ADS)

    Yu, Feifei; Wang, Hefeng; Yuan, Guozheng; Shu, Xuefeng

    2017-04-01

    Arc melting with nonconsumable tungsten electrode and water-cooled copper crucible was used to fabricate Ti-Cu binary alloys with different Cu contents in an argon atmosphere. The compositions and phase structures of the fabricated alloys were investigated by glow discharge optical emission spectroscopy (GDOES) and X-ray diffraction (XRD). Nanoindentation tests through continuous stiffness measurement were then performed at room temperature to analyze the mechanical behaviors of the alloys. Results indicated that the composition of each Ti-Cu binary alloy was Ti(100- x) Cu x ( x = 43, 60, 69, and 74 at.%). The XRD analysis results showed that the alloys were composed of different phases, indicating that different Cu contents led to the variations in alloy hardness. The wear tests results revealed that elemental Cu positively affects the wear resistance properties of the Ti-Cu alloys. Nanoindentation testing results showed that the moduli of the Ti-Cu alloys were minimally changed at increasing Cu content, whereas their hardness evidently increased according to the wear test results.

  9. Laser Tailoring the Surface Chemistry and Morphology for Wear, Scale and Corrosion Resistant Superhydrophobic Coatings.

    PubMed

    Boinovich, Ludmila B; Emelyanenko, Kirill A; Domantovsky, Alexander G; Emelyanenko, Alexandre M

    2018-06-04

    A strategy, combining laser chemical modification with laser texturing, followed by chemisorption of the fluorinated hydrophobic agent was used to fabricate the series of superhydrophobic coatings on an aluminum alloy with varied chemical compositions and parameters of texture. It was shown that high content of aluminum oxynitride and aluminum oxide formed in the surface layer upon laser treatment allows solving the problem of enhancement of superhydrophobic coating resistance to abrasive loads. Besides, the multimodal structure of highly porous surface layer leads to self-healing ability of fabricated coatings. Long-term behavior of designed coatings in "hard" hot water with an essential content of calcium carbonate demonstrated high antiscaling resistance with self-cleaning potential against solid deposits onto the superhydrophobic surfaces. Study of corrosion protection properties and the behavior of coatings at long-term contact with 0.5 M NaCl solution indicated extremely high chemical stability and remarkable anticorrosion properties.

  10. Microstructure and wear resistance of laser cladded composite coatings prepared from pre-alloyed WC-NiCrMo powder with different laser spots

    NASA Astrophysics Data System (ADS)

    Yao, Jianhua; Zhang, Jie; Wu, Guolong; Wang, Liang; Zhang, Qunli; Liu, Rong

    2018-05-01

    The distribution of WC particles in laser cladded composite coatings can significantly affect the wear resistance of the coatings under aggressive environments. In this study, pre-alloyed WC-NiCrMo powder is deposited on SS316L via laser cladding with circular spot and wide-band spot, respectively. The microstructure and WC distribution of the coatings are investigated with optical microscope (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). The wear behavior of the coatings is investigated under dry sliding-wear test. The experimental results show that the partially dissolved WC particles are uniformly distributed in both coatings produced with circular spot and wide-band spot, respectively, and the microstructures consist of WC and M23C6 carbides and γ-(Ni, Fe) solid solution matrix. However, due to Fe dilution, the two coatings have different microstructural characteristics, resulting in different hardness and wear resistance. The wide-band spot laser prepared coating shows better performance than the circular spot laser prepared coating.

  11. Improved wear resistance of functional diamond like carbon coated Ti-6Al-4V alloys in an edge loading conditions.

    PubMed

    Choudhury, Dipankar; Lackner, Jürgen M; Major, Lukasz; Morita, Takehiro; Sawae, Yoshinori; Bin Mamat, Azuddin; Stavness, Ian; Roy, Chanchal K; Krupka, Ivan

    2016-06-01

    This study investigates the durability of functional diamond-like carbon (DLC) coated titanium alloy (Ti-6Al-4V) under edge loading conditions for application in artificial hip joints. The multilayered (ML) functional DLC coatings consist of three key layers, each of these layers were designed for specific functions such as increasing fracture strength, adapting stress generation and enhancing wear resistance. A 'ball-on-disk' multi-directional wear tester was used in the durability test. Prior to the wear testing, surface hardness, modulus elasticity and Raman intensity were measured. The results revealed a significant wear reduction to the DLC coated Ti-6Al-4V disks compared to that of non-coated Ti-6Al-4V disks. Remarkably, the counterpart Silicon Nitride (Si3N4) balls also yielded lowered specific wear rate while rubbed against the coated disks. Hence, the pairing of a functional multilayered DLC and Si3N4 could be a potential candidate to orthopedics implants, which would perform a longer life-cycle against wear caused by edge loading. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Wear Resistance Enhancement of Ti-6Al-4 V Alloy by Applying Zr-Modified Silicide Coatings

    NASA Astrophysics Data System (ADS)

    Li, Xuan; Hu, Guangzhong; Tian, Jin; Tian, Wei; Xie, Wenling; Li, Xiulan

    2018-03-01

    Zr-modified silicide coatings were prepared on Ti-6Al-4 V alloy by pack cementation process to enhance its wear resistance. The microstructure and wear properties of the substrate and the coatings were comparatively investigated using GCr15 and Al2O3 as the counterparts under different sliding loads. The obtained Zr-modified silicide coating had a multilayer structure, consisting of a thick (Ti, X)Si2 (X represents Al, Zr and V elements) outer layer, a TiSi middle layer and a Ti5Si4 + Ti5Si3 inner layer. The micro-hardness of the coating was much higher than the substrate and displayed a decrease tendency from the coating surface to the interior. Sliding against either GCr15 or Al2O3 balls, the coatings showed superior anti-friction property to the Ti-6Al-4 V alloy, as confirmed by its much lower wear rate under each employed sliding condition.

  13. An abrasion-resistant and broadband antireflective silica coating by block copolymer assisted sol-gel method.

    PubMed

    Zou, Liping; Li, Xiaoguang; Zhang, Qinghua; Shen, Jun

    2014-09-02

    A double-layer broadband antireflective (AR) coating was prepared on glass substrate via sol-gel process using two kinds of acid-catalyzed TEOS-derived silica sols. The relative dense layer with a porosity of ∼10% was obtained from an as-prepared sol, while the porous layer with a porosity of ∼55% was from a modified one with block copolymer (BCP) Pluronic F127 as template which results in abundant ordered mesopores. The two layers give rise to a reasonable refractive index gradient from air to the substrate and thus high transmittance in a wide wavelength range, and both of them have the same tough skeleton despite different porosity, for which each single-layer and the double-layer coatings all behaved well in the mechanical property tests. The high transmittance and the strong ability of resisting abrasion make this coating promising for applications in some harsh conditions. In addition, the preparation is simple, low-cost, time-saving, and flexible for realizing the optical property.

  14. Laser-Assisted Cold-Sprayed Corrosion- and Wear-Resistant Coatings: A Review

    NASA Astrophysics Data System (ADS)

    Olakanmi, E. O.; Doyoyo, M.

    2014-06-01

    Laser-assisted cold spray (LACS) process will be increasingly employed for depositing coatings because of its unique advantages: solid-state deposition of dense, homogeneous, and pore-free coatings onto a range of substrates; and high build rate at reduced operating costs without the use of expensive heating and process inert gases. Depositing coatings with excellent performance indicators via LACS demands an accurate knowledge and control of processing and materials' variables. By varying the LACS process parameters and their interactions, the functional properties of coatings can be manipulated. Moreover, thermal effect due to laser irradiation and microstructural evolution complicate the interpretation of LACS mechanical deformation mechanism which is essential for elucidating its physical phenomena. In order to provide a basis for follow-on-research that leads to the development of high-productivity LACS processing of coatings, this review focuses on the latest developments in depositing corrosion- and wear-resistant coatings with the emphasis on the composition, structure, and mechanical and functional properties. Historical developments and fundamentals of LACS are addressed in an attempt to describe the physics behind the process. Typical technological applications of LACS coatings are also identified. The investigations of all process sequences, from laser irradiation of the powder-laden gas stream and the substrate, to the impingement of thermally softened particles on the deposition site, and subsequent further processes, are described. Existing gaps in the literature relating to LACS-dependent microstructural evolution, mechanical deformation mechanisms, correlation between functional properties and process parameters, processing challenges, and industrial applications have been identified in order to provide insights for further investigations and innovation in LACS deposition of wear- and corrosion-resistant coatings.

  15. Rapid Analyses of Polyetheretherketone Wear Characteristics by Accelerated Wear Testing with Microfabricated Surfaces for Artificial Joint Systems

    PubMed Central

    Kuo, Chien-Wei

    2017-01-01

    Wear particle-induced biological responses are the major factors resulting in the loosening and then failure of total joint arthroplasties. It is feasible to improve the lubrication and reduce the wear of artificial joint system. Polyetheretherketone (PEEK) is considered as a potential bearing material due to its mechanical characteristics of resistance to fatigue strain. The PEEK wear particles have been indicated to be involved in biological responses in vitro, and further studies regarding the wear phenomena and wear particle generation are needed. In this study, we have established an accelerated wear testing system with microfabricated surfaces. Various contact pressures and lubricants have been utilized in the accelerated wear tests. Our results showed that increasing contact pressure resulted in an increase of wear particle sizes and wear rate, and the size of PEEK wear particles can be controlled by the feature size of microfabricated surfaces. These results provided the information rapidly about factors that affect the morphology and amount of PEEK wear particles and can be applied in the future for application of PEEK on the biological articulation system. PMID:29230411

  16. Rapid Analyses of Polyetheretherketone Wear Characteristics by Accelerated Wear Testing with Microfabricated Surfaces for Artificial Joint Systems.

    PubMed

    Su, Chen-Ying; Kuo, Chien-Wei; Fang, Hsu-Wei

    2017-01-01

    Wear particle-induced biological responses are the major factors resulting in the loosening and then failure of total joint arthroplasties. It is feasible to improve the lubrication and reduce the wear of artificial joint system. Polyetheretherketone (PEEK) is considered as a potential bearing material due to its mechanical characteristics of resistance to fatigue strain. The PEEK wear particles have been indicated to be involved in biological responses in vitro, and further studies regarding the wear phenomena and wear particle generation are needed. In this study, we have established an accelerated wear testing system with microfabricated surfaces. Various contact pressures and lubricants have been utilized in the accelerated wear tests. Our results showed that increasing contact pressure resulted in an increase of wear particle sizes and wear rate, and the size of PEEK wear particles can be controlled by the feature size of microfabricated surfaces. These results provided the information rapidly about factors that affect the morphology and amount of PEEK wear particles and can be applied in the future for application of PEEK on the biological articulation system.

  17. Effect of Microstructural Evolution and Hardening in Subsurface on Wear Behavior of Mg-3Al-1Zn Alloy

    NASA Astrophysics Data System (ADS)

    Liang, C.; Li, C.; An, J.; Yu, M.; Hu, Y. C.; Lin, W. H.; Liu, F.; Ding, Y. H.

    2013-12-01

    Dry sliding tests were performed on as-cast AZ31 alloy using a pin-on-disc configuration. Coefficient of friction and wear rate were measured within a load range of 5-360 N at a sliding velocity of 0.785 m/s. Worn surface morphologies were examined using scanning electron microscopy. Five wear mechanisms, namely abrasion, oxidation, delamination, thermal softening, and melting, have been observed. Surface hardness, subsurface plastic strain, worn surface temperature, and cross-sectional optical microscopy were used to characterize hardness change, plastic deformation, and the microstructure evolution in subsurface. The results illustrate the correlation between the wear behavior and evolution of microstructure and hardness in subsurface, and reveal that in the load range of 5-120 N, surface oxidation and hardening originating from large plastic deformation play an important role in maintaining the mild wear, and softening originating from dynamic recrystallization in subsurface and surface melting are responsible for the severe wear in the load range of 120-360 N.

  18. CR TKA UHMWPE wear tested after artificial aging of the vitamin E treated gliding component by simulating daily patient activities.

    PubMed

    Schwiesau, Jens; Fritz, Bernhard; Kutzner, Ines; Bergmann, Georg; Grupp, Thomas M

    2014-01-01

    The wear behaviour of total knee arthroplasty (TKA) is dominated by two wear mechanisms: the abrasive wear and the delamination of the gliding components, where the second is strongly linked to aging processes and stress concentration in the material. The addition of vitamin E to the bulk material is a potential way to reduce the aging processes. This study evaluates the wear behaviour and delamination susceptibility of the gliding components of a vitamin E blended, ultra-high molecular weight polyethylene (UHMWPE) cruciate retaining (CR) total knee arthroplasty. Daily activities such as level walking, ascending and descending stairs, bending of the knee, and sitting and rising from a chair were simulated with a data set received from an instrumented knee prosthesis. After 5 million test cycles no structural failure of the gliding components was observed. The wear rate was with 5.62 ± 0.53 mg/million cycles falling within the limit of previous reports for established wear test methods.

  19. CR TKA UHMWPE Wear Tested after Artificial Aging of the Vitamin E Treated Gliding Component by Simulating Daily Patient Activities

    PubMed Central

    Schwiesau, Jens; Fritz, Bernhard; Kutzner, Ines; Bergmann, Georg; Grupp, Thomas M.

    2014-01-01

    The wear behaviour of total knee arthroplasty (TKA) is dominated by two wear mechanisms: the abrasive wear and the delamination of the gliding components, where the second is strongly linked to aging processes and stress concentration in the material. The addition of vitamin E to the bulk material is a potential way to reduce the aging processes. This study evaluates the wear behaviour and delamination susceptibility of the gliding components of a vitamin E blended, ultra-high molecular weight polyethylene (UHMWPE) cruciate retaining (CR) total knee arthroplasty. Daily activities such as level walking, ascending and descending stairs, bending of the knee, and sitting and rising from a chair were simulated with a data set received from an instrumented knee prosthesis. After 5 million test cycles no structural failure of the gliding components was observed. The wear rate was with 5.62 ± 0.53 mg/million cycles falling within the limit of previous reports for established wear test methods. PMID:25506594

  20. Toothbrush abrasion of paint-on resins for shade modification and crown resins: effect of water absorption.

    PubMed

    Fujii, Koichi; Arikawa, Hiroyuki; Kanie, Takahito; Ban, Seiji

    2004-06-01

    In order to investigate the clinical application of paint-on resins, the effect of water absorption on toothbrush abrasion and light transmittance of ten crown resins including three paint-on resins was examined. Water absorption into each material ranged from 0.29 to 0.89 mg/cm2 after storage in distilled-water for 6 weeks and their hardnesses decreased by 3.5-22.3%. Maximum surface roughness (Rmax) of the materials stored in distilled water for 6 weeks increased with an increasing number of toothbrush abrasion cycles and ranged from 1.9 to 10.5 microm after 100,000 cycles. Also, Maximum depth and weight loss as an indicator of the amount of each material lost by abrasion showed similar behaviors similar to Rmax. These results indicated that the abrasion resistance of paint-on resins was located in the middle among all materials examined.

  1. Comparison of the Effect of Addition of Cyanoacrylate, Epoxy Resin, and Gum Arabic on Surface Hardness of Die Stone.

    PubMed

    Tripathi, Arvind; Gupta, Ashutosh; Bagchi, Soumyojeet; Mishra, Lallan; Gautam, Abhina; Madhok, Riti

    2016-04-01

    To observe the effects of incorporating cyanoacrylate, epoxy resins, and gum arabic on the abrasion resistance of type IV gypsum die materials. Forty specimens were prepared and divided into four groups (10 specimens in each group), namely group A (control), group B (die stone mixed with cyanoacrylate), group C (die stone mixed with epoxy resin), group D (die stone mixed with gum arabic). All the specimens were subjected to abrasion testing, wear volume analysis, Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM) analysis. Abrasion testing showed maximum wear in the control group and minimum wear in the gum arabic group. Intergroup differences were statistically significant (p < 0.001). The largest mean difference was between control and gum arabic. The lowest was between cyanoacrylate and the control group. The mean wear volume was lowest in the gum arabic group (4.23 mm(3) ) and highest in the control group (6.78 mm(3) ). The FT-IR graphs of the gum arabic models showed the presence of CH2 , which is responsible for its binding activity. SEM revealed that the irregular particles of gum arabic display an interlocking arrangement. This jigsaw puzzle pattern results in stronger physical bond formation. Observations from this study showed that the addition of gum arabic increases resistance to abrasion in type IV gypsum. Cyanoacrylates are good adhesives as well, but a major drawback is that they have very low resistance to chemical action with water and physical actions such as sunlight. Epoxy resins are powerful adhesives, but they attain their full efficiency when cured with heat. Cyanoacrylate and epoxy resin displayed poor physical bonding, primarily because of inhomogeneity. © 2015 by the American College of Prosthodontists.

  2. Multidirectional wear and impact-to-wear tests of phospholipid-polymer-grafted and vitamin E-blended crosslinked polyethylene: a pilot study.

    PubMed

    Kyomoto, Masayuki; Moro, Toru; Takatori, Yoshio; Tanaka, Sakae; Ishihara, Kazuhiko

    2015-03-01

    Modifying the surface and substrate of a crosslinked polyethylene (CLPE) liner may be beneficial for high wear resistance as well as high oxidative stability and excellent mechanical properties, which would be useful in contributing to the long-term performance of orthopaedic bearings. A grafted poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer on a vitamin E-blended crosslinked PE (HD-CLPE[VE]) surface may provide hydrophilicity and lubricity without compromising the oxidative stability or mechanical properties. (1) Will the modifications (PMPC grafting and vitamin E blending) affect the lubrication characteristics of the CLPE surface? (2) Will the modifications affect wear resistance? (3) Will the modifications affect fatigue resistance? We investigated the effects of surface and substrate modifications (PMPC grafting and vitamin E blending) on the wear and fatigue fracture of thin CLPE samples. For each of the untreated and PMPC-grafted CLPE surfaces with and without vitamin E blended (four groups), wettability and lubricity surface analyses were conducted as well as multidirectional wear and impact-to-wear tests using a pin-on-disk testing machine. The water wettability and lubricity (CLPE [mean ± 95% confidence interval]: 23.2° ± 1.8°, 0.005 ± 0.001; HD-CLPE[VE]: 26.0° ± 2.3°, 0.009 ± 0.003) of the PMPC-grafted surfaces were greater (p < 0.001) than that (CLPE: 90.3° ± 1.2°, 0.067 ± 0.015; HD-CLPE[VE]: 90.8° ± 2.0°, 0.063 ± 0.008) of the untreated surface regardless of vitamin E additives. It was observed that the PMPC grafting (CLPE: 0.23 ± 0.06 mg; HD-CLPE[VE]: 0.05 ± 0.10 mg) was associated with reduced gravimetric wear (CLPE: 0.53 ± 0.08 mg, p = 0.004 HD-CLPE[VE]: 0.23 ± 0.07 mg, p = 0.038) in the multidirectional wear test. The PMPC-grafted surface characteristics did not appear to affect the impact fatigue resistance regardless of vitamin E blending. PMPC grafting improved the surface hydrophilicity and lubricity, and it

  3. TiN-Coating Effects on Stainless Steel Tribological Behavior Under Dry and Lubricated Conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Liqiang; Yang, Huisheng; Pang, Xiaolu; Gao, Kewei; Tran, Hai T.; Volinsky, Alex A.

    2014-04-01

    The tribological properties of magnetron sputtered titanium nitride coating on 316L steel, sliding against Si3N4 ceramic ball under dry friction and synthetic perspiration lubrication, were investigated. The morphology of the worn surface and the elemental composition of the wear debris were examined by scanning electron microscopy and energy dispersive spectroscopy. TiN coatings and 316L stainless steel had better tribological properties under synthetic perspiration lubrication than under dry friction. Among the three tested materials (316L, 1.6 and 2.4 μm TiN coatings), 2.4 μm TiN coating exhibits the best wear resistance. The difference in wear damage of the three materials is essentially due to the wear mechanisms. For the TiN coating, the damage is attributed to abrasive wear under synthetic perspiration lubrication and the complex interactive mechanisms, including abrasive and adhesive wear, along with plastic deformation, under dry friction.

  4. Tribology Study of High-Technological Composite Coatings Applied Using High Velocity Oxy-Fuel

    NASA Astrophysics Data System (ADS)

    Kandeva, M.; Grozdanova, T.; Karastoyanov, D.; Ivanov, Pl; Kalichin, Zh

    2018-01-01

    In the work are studied the differential parameters of wear and wear resistance of high-tech composite coatings of powder superalloys with nickel matrix, WC-12Co and mixed compositions. Coatings were created and applied to a substrate of steel with a different flame velocity - 700 m/s and 1000 m/s without preheating the substrate and with preheating the substrate to 650° C. The wear is carried out with a "thumb-disk" tribotester under dry surface friction with fixed black corundum abrasive particles. Comparative results were obtained for the microstructure and texture of the pre- and post- friction coating, the porosity, roughness, hardness, the dependence of mass wear, the speed and wear intensity and the wear resistance of the coatings on the number of friction cycles. Influence of the flame rate and substrate temperature on wear resistance and differential wear parameters has been determined.

  5. Dry sliding wear of heat treated hybrid metal matrix composites

    NASA Astrophysics Data System (ADS)

    Naveed, Mohammed; Khan, A. R. Anwar

    2016-09-01

    In recent years, there has been an ever-increasing demand for enhancing mechanical properties of Aluminum Matrix Composites (AMCs), which are finding wide applications in the field of aerospace, automobile, defence etc,. Among all available aluminium alloys, Al6061 is extensively used owing to its excellent wear resistance and ease of processing. Newer techniques of improving the hardness and wear resistance of Al6061 by dispersing an appropriate mixture of hard ceramic powder and whiskers in the aluminium alloy are gaining popularity. The conventional aluminium based composites possess only one type of reinforcements. Addition of hard reinforcements such as silicon carbide, alumina, titanium carbide, improves hardness, strength and wear resistance of the composites. However, these composites possessing hard reinforcement do posses several problems during their machining operation. AMCs reinforced with particles of Gr have been reported to be possessing better wear characteristics owing to the reduced wear because of formation of a thin layer of Gr particles, which prevents metal to metal contact of the sliding surfaces. Further, heat treatment has a profound influence on mechanical properties of heat treatable aluminium alloys and its composites. For a solutionising temperature of 5500C, solutionising duration of 1hr, ageing temperature of 1750C, quenching media and ageing duration significantly alters mechanical properties of both aluminium alloy and its composites. In the light of the above, the present paper aims at developing aluminium based hybrid metal matrix composites containing both silicon carbide and graphite and characterize their mechanical properties by subjecting it to heat treatment. Results indicate that increase of graphite content increases wear resistance of hybrid composites reinforced with constant SiC reinforcement. Further heat treatment has a profound influence on the wear resistance of the matrix alloy as well as its hybrid composites

  6. Investigation on wear resistance and corrosion resistance of electron beam cladding co-alloy coating on Inconel617

    NASA Astrophysics Data System (ADS)

    Liu, Hailang; Zhang, Guopei; Huang, Yiping; Qi, Zhengwei; Wang, Bo; Yu, Zhibiao; Wang, Dezhi

    2018-04-01

    To improve surface properties of Inconel 617 alloy (referred to as 617 alloy), co-alloy coating metallurgically bonded to substrate was prepared on the surface of 617 alloy by electron beam cladding. The microstructure, phase composition, microhardness, tribological properties and corrosion resistance of the coatings were investigated. The XRD results of the coatings reinforced by co-alloy (Co800) revealed the presence of γ-Co, CoCx and Cr23C6 phase as matrix and new metastable phases of Cr2Ni3 and Co3Mo2Si. These hypoeutectic structures contain primary dendrites and interdendritic eutectics. The metallurgical bonding forms well between the cladding layer and the matrix of 617 alloy. In most studied conditions, the co-alloy coating displays a better hardness, tribological performance, i.e., lower coefficient of frictions and wear rates, corrosion resistance in 1 mol L‑1 HCl solution, than the 617 alloy.

  7. Study on design of light-weight super-abrasive wheel

    NASA Astrophysics Data System (ADS)

    Nohara, K.; Yanagihara, K.; Ogawa, M.

    2018-01-01

    Fixed-abrasive tool, also called a grinding wheel, is produced by furnacing abrasive compound which contains abrasive grains and binding powder such as vitrified materials or resins. Fixed-abrasive tool is installed on spindle of grinding machine. And it is given 1,800-2,000 min-1 of spindle rotation for the usage. The centrifugal fracture of the compound of fixed- abrasive tool is one of the careful respects in designing. In recent years, however, super-abrasive wheel as a fixed-abrasive tool has been developed and applied widely. One of the most characteristic respects is that metal is applied for the body of grinding-wheel. The strength to hold abrasive grain and the rigidity of wheel become stronger than those of general grinding wheel, also the lifespan of fixed-abrasive tool becomes longer. The weight of fixed-abrasive tool, however, becomes heavier. Therefore, when the super-abrasive wheel is used, the power consumption of spindle motor becomes larger. It also becomes difficult for the grinding-wheel to respond to sudden acceleration or deceleration. Thus, in order to reduce power consumption in grinding and to obtain quicker frequency response of super-abrasive wheel, the new wheel design is proposed. The design accomplishes 46% weight reduction. Acceleration that is one second quicker than that of conventional grinding wheel is obtained.

  8. Abrasion behavior of aluminum and composite skin coupons, stiffened skins and stiffened panels representative of transport airplane structures

    NASA Technical Reports Server (NTRS)

    Jackson, K. E.

    1985-01-01

    A three-phase investigation was conducted to compare the friction and wear response of aluminum and graphite-epoxy composite materials when subjected to loading conditions similar to those experienced by the skin panels on the underside of a transport airplane during an emergency belly landing on a runway surface. The first phase involved a laboratory test which used a standard belt sander to provide the sliding abrasive surface. Small skin-coupon test specimens were abraded over a range of pressures and velocities to determine the effects of these variables on the coefficient of friction and wear rate. The second phase involved abrading I-beam stiffened skins on actual runway surface over the same range of pressures and velocities used in the first phase. In the third phase, large stiffened panels which most closely resembled transport fuelage skin construction were abraded on a runway surface. This report presents results from each phase of the investigation and shows comparisons between the friction and wear behavior of the aluminum and graphite-epoxy composite materials.

  9. Mechanical properties and bio-tribological behaviors of novel beta-Zr-type Zr-Al-Fe-Nb alloys for biomedical applications.

    PubMed

    Hua, Nengbin; Chen, Wenzhe; Zhang, Lei; Li, Guanghui; Liao, Zhenlong; Lin, Yan

    2017-07-01

    The present study prepares novel Zr 70+x Al 5 Fe 15-x Nb 10 (x=0, 5) alloys by arc-melting for potential biomedical application. The mechanical properties and bio-tribological behaviors of the Zr-based alloys are evaluated and compared with biomedical pure Zr. The as-prepared alloys exhibit a microstructure containing a micrometer-sized dendritic beta-Zr phase dispersed in a Zr 2 Fe-typed matrix. It is found that increasing the content of Zr is favorable for the mechanical compatibility with a combination of low Young's modulus, large plasticity, and high compressive strength. The wear resistance of the Zr-Al-Fe-Nb alloys in air and phosphate buffer saline (PBS) solution is superior to that of pure Zr. The wear mechanism of Zr-based alloys sliding in air is controlled by oxidation and abrasive wear whereas that sliding in PBS is controlled by synergistic effects of the abrasive and corrosive wear. Electrochemical measurements demonstrate that the Zr-based alloys are corrosion resistant in PBS. Their bio-corrosion resistance is improved with the increase in Zr content, which is attributed to the enrichment in Zr and decrease in Al concentration in the surface passive film of alloys. The Zr 75 Al 5 Fe 10 Nb 10 exhibits the best corrosion resistance in PBS, which contributes to its superior wear resistance in a simulated body environment. The combination of good mechanical properties, corrosion resistance, and biotribological behaviors of the Zr-Al-Fe-Nb alloys offers them potential advantages in biomedical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. High Strength and Wear Resistant Aluminum Alloy for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.; Chen, Po Shou

    2003-01-01

    Originally developed by NASA as high performance piston alloys to meet U.S. automotive legislation requiring low exhaust emission, the novel NASA alloys now offer dramatic increase in tensile strength for many other applications at elevated temperatures from 450 F (232 C) to about 750 F (400 C). It is an ideal low cost material for cast automotive components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. It can be very economically produced from conventional permanent mold, sand casting or investment casting, with silicon content ranging from 6% to 18%. At high silicon levels, the alloy exhibits excellent thermal growth stability, surface hardness and wear resistant properties.

  11. Investigation of Selective Laser Melting Surface Alloyed Aluminium Metal Matrix Dispersive Reinforced Layers

    NASA Astrophysics Data System (ADS)

    Kamburov, V. V.; Dimitrova, R. B.; Kandeva, M. K.; Sofronov, Y. P.

    2018-01-01

    The aim of the paper is to investigate the improvement of mechanical properties and in particular wear resistance of laser surface alloyed dispersive reinforced thin layers produced by selective laser melting (SLM) technology. The wear resistance investigation of aluminium matrix composite layers in the conditions of dry friction surface with abrasive particles and nanoindentation tests were carried out. The process parameters (as scan speed) and their impact on the wear resistant layers have been evaluated. The alloyed layers containing metalized SiC particles were studied by Optical and Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray microanalysis (EDX). The obtained experimental results of the laser alloyed thin layers show significant development of their wear resistance and nanohardness due to the incorporated reinforced phase of electroless nickel coated SiC particles.

  12. Enhancing Corrosion and Wear Resistance of AA6061 by Friction Stir Processing with Fe78Si9B13 Glass Particles

    PubMed Central

    Guo, Lingyu; Liu, Yan; Shen, Kechang; Song, Chaoqun; Yang, Min; Kim, Kibuem; Wang, Weimin

    2015-01-01

    The AA6061-T6 aluminum alloy samples including annealed Fe78Si9B13 particles were prepared by friction stir processing (FSP) and investigated by various techniques. The Fe78Si9B13-reinforced particles are uniformly dispersed in the aluminum alloy matrix. The XRD results indicated that the lattice parameter of α-Al increases and the preferred orientation factors F of (200) plane of α-Al reduces after friction stir processing. The coefficient of thermal expansion (CTE) for FSP samples increases at first with the temperature but then decreases as the temperature further increased, which can be explained by the dissolving of Mg and Si from β phase and Fe78Si9B13 particles. The corrosion and wear resistance of FSP samples have been improved compared with that of base metal, which can be attributed to the reduction of grain size and the CTE mismatch between the base metal and reinforced particles by FSP, and the lubrication effect of Fe78Si9B13 particles also plays a role in improving wear resistance. In particular, the FSP sample with reinforced particles in amorphous state exhibited superior corrosion and wear resistance due to the unique metastable structure. PMID:28793492

  13. Time series analysis of tool wear in sheet metal stamping using acoustic emission

    NASA Astrophysics Data System (ADS)

    Vignesh Shanbhag, V.; Pereira, P. Michael; Rolfe, F. Bernard; Arunachalam, N.

    2017-09-01

    Galling is an adhesive wear mode that often affects the lifespan of stamping tools. Since stamping tools represent significant economic cost, even a slight improvement in maintenance cost is of high importance for the stamping industry. In other manufacturing industries, online tool condition monitoring has been used to prevent tool wear-related failure. However, monitoring the acoustic emission signal from a stamping process is a non-trivial task since the acoustic emission signal is non-stationary and non-transient. There have been numerous studies examining acoustic emissions in sheet metal stamping. However, very few have focused in detail on how the signals change as wear on the tool surface progresses prior to failure. In this study, time domain analysis was applied to the acoustic emission signals to extract features related to tool wear. To understand the wear progression, accelerated stamping tests were performed using a semi-industrial stamping setup which can perform clamping, piercing, stamping in a single cycle. The time domain features related to stamping were computed for the acoustic emissions signal of each part. The sidewalls of the stamped parts were scanned using an optical profilometer to obtain profiles of the worn part, and they were qualitatively correlated to that of the acoustic emissions signal. Based on the wear behaviour, the wear data can be divided into three stages: - In the first stage, no wear is observed, in the second stage, adhesive wear is likely to occur, and in the third stage severe abrasive plus adhesive wear is likely to occur. Scanning electron microscopy showed the formation of lumps on the stamping tool, which represents galling behavior. Correlation between the time domain features of the acoustic emissions signal and the wear progression identified in this study lays the basis for tool diagnostics in stamping industry.

  14. Corneal Abrasions

    MedlinePlus

    ... the doctor looks at the eye under a light that is filtered cobalt blue. The fluorescein causes the abrasion to glow bright green under the light. The doctor also might do a standard ophthalmic ...

  15. Laboratory testing of airborne brake wear particle emissions using a dynamometer system under urban city driving cycles

    NASA Astrophysics Data System (ADS)

    Hagino, Hiroyuki; Oyama, Motoaki; Sasaki, Sousuke

    2016-04-01

    To measure driving-distance-based mass emission factors for airborne brake wear particulate matter (PM; i.e., brake wear particles) related to the non-asbestos organic friction of brake assembly materials (pads and lining), and to characterize the components of brake wear particles, a brake wear dynamometer with a constant-volume sampling system was developed. Only a limited number of studies have investigated brake emissions under urban city driving cycles that correspond to the tailpipe emission test (i.e., JC08 or JE05 mode of Japanese tailpipe emission test cycles). The tests were performed using two passenger cars and one middle-class truck. The observed airborne brake wear particle emissions ranged from 0.04 to 1.4 mg/km/vehicle for PM10 (particles up to 10 μm (in size), and from 0.04 to 1.2 mg/km/vehicle for PM2.5. The proportion of brake wear debris emitted as airborne brake wear particles was 2-21% of the mass of wear. Oxygenated carbonaceous components were included in the airborne PM but not in the original friction material, which indicates that changes in carbon composition occurred during the abrasion process. Furthermore, this study identified the key tracers of brake wear particles (e.g., Fe, Cu, Ba, and Sb) at emission levels comparable to traffic-related atmospheric environments.

  16. [Destructive and protective factors in the development of tooth-wear].

    PubMed

    Jász, Máté; Varga, Gábor; Tóth, Zsuzsanna

    2006-12-01

    The experience of the past decade proves that tooth wear occurs in an increasing number of cases in general dental practice. Tooth wear may have physical (abrasion and attrition) and/or chemical (erosion) origin. The primary physical causes are inadequate dental hygienic activities, bad oral habits or occupational harm. As for dental erosion, it is accelerated by the highly erosive foods and drinks produced and sold in the past decades, and the number of cases is also boosted by the fact that bulimia, anorexia nervosa and gastro-oesophageal reflux disease prevalence have become more common. The most important defensive factor against tooth wear is saliva, which protects teeth from the effect of acids. Tertiary dentin formation plays an important role in the protection of the pulp. Ideally, destructive and protective factors are in balance. Both an increase in the destructive forces, and the insufficiency of defense factors result in the disturbance of the equilibrium. This results in tooth-wear, which means an irreversible loss of dental hard tissue. The rehabilitation of the lost tooth material is often very difficult, irrespectively of whether it is needed because of functional or esthetic causes. For that reason, the dentist should carry out primary and secondary dental care and prevention more often, i.e. dental recall is indispensable every 4-6 months.

  17. Wear behavior of electroless Ni-P-W coating under lubricated condition - a Taguchi based approach

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Arkadeb; Duari, Santanu; Barman, Tapan Kumar; Sahoo, Prasanta

    2016-09-01

    The present study aims to investigate the tribological behavior of electroless Ni-P-W coating under engine oil lubricated condition to ascertain its suitability in automotive applications. Coating is deposited onto mild steel specimens by the electroless method. The experiments are carried out on a pin - on - disc type tribo tester under lubrication. Three tribotesting parameters namely the applied normal load, sliding speed and sliding duration are varied at their three levels and their effects on the wear depth of the deposits are studied. The experiments are carried out based on the combinations available in Taguchi's L27 orthogonal array (OA). Optimization of the tribo-testing parameters is carried out using Taguchi's S/N ratio method to minimize the wear depth. Analysis of variance carried out at a confidence level of 99% indicates that the sliding speed is the most significant parameter in controlling the wear behavior of the deposits. Coating characterization is done using scanning electron microscope, energy dispersive X-ray analysis and X-ray diffraction techniques. It is seen that the wear mechanism under lubricated condition is abrasive in nature.

  18. Ceramic-bonded abrasive grinding tools

    DOEpatents

    Holcombe, C.E. Jr.; Gorin, A.H.; Seals, R.D.

    1994-11-22

    Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

  19. Ceramic-bonded abrasive grinding tools

    DOEpatents

    Holcombe, Jr., Cressie E.; Gorin, Andrew H.; Seals, Roland D.

    1994-01-01

    Abrasive grains such as boron carbide, silicon carbide, alumina, diamond, cubic boron nitride, and mullite are combined with a cement primarily comprised of zinc oxide and a reactive liquid setting agent and solidified into abrasive grinding tools. Such grinding tools are particularly suitable for grinding and polishing stone, such as marble and granite.

  20. Mesenchymal stem cell interaction with ultra smooth nanostructured diamond for wear resistant orthopaedic implants

    PubMed Central

    Clem, William C.; Chowdhury, Shafiul; Catledge, Shane A.; Weimer, Jeffrey J.; Shaikh, Faheem M.; Hennessy, Kristin M.; Konovalov, Valery V.; Hill, Michael R.; Waterfeld, Alfred; Bellis, Susan L.; Vohra, Yogesh K.

    2008-01-01

    Ultra smooth nanostructured diamond (USND) can be applied to greatly increase the wear resistance of orthopaedic implants over conventional designs. Herein we describe surface modification techniques and cytocompatibility studies performed on this new material. We report that hydrogen (H) -terminated USND surfaces supported robust mesenchymal stem cell (MSC) adhesion and survival, while oxygen (O) and fluorine (F) -terminated surfaces resisted cell adhesion, indicating that USND can be modified to either promote or prevent cell/biomaterial interactions. Given the favorable cell response to H-terminated USND, this material was further compared with two commonly-used biocompatible metals, titanium alloy (Ti-6Al-4V) and cobalt chrome (CoCrMo). MSC adhesion and proliferation were significantly improved on USND compared with CoCrMo, although cell adhesion was greatest on Ti-6Al-4V. Comparable amounts of the proadhesive protein, fibronectin, were deposited from serum on the three substrates. Finally, MSCs were induced to undergo osteoblastic differentiation on the three materials, and deposition of a mineralized matrix was quantified. Similar amounts of mineral were deposited onto USND and CoCrMo, whereas mineral deposition was slightly higher on Ti-6Al-4V. When coupled with recently published wear studies, these in vitro results suggest that USND has the potential to reduce debris particle release from orthopaedic implants without compromising osseointegration. PMID:18490051