Sample records for galling wear resistance

  1. Effect of Temperature on Galling Behavior of SS 316, 316 L and 416 Under Self-Mated Condition

    NASA Astrophysics Data System (ADS)

    Harsha, A. P.; Limaye, P. K.; Tyagi, Rajnesh; Gupta, Ankit

    2016-11-01

    Galling behavior of three different stainless steels (SS 316, 316 L and 416) was evaluated at room temperature and 300 °C under a self-mated condition. An indigenously fabricated galling tester was used to evaluate the galling performance of mated materials as per ASTM G196-08 standard. The variation in frictional torque was recorded online during the test to assess the onset of galling. The galling50 (G50) stress value was used to compare the galling resistance of a combination of materials, and the results indicate a significant influence of temperature on the galling resistance of the materials tested. This has been attributed to the decrease in hardness and yield strength at elevated temperature which results in softening of the steel and limits its ability to resist severe deformation. Scanning electron micrographs of the galled surface reflected a severe plastic deformation in sliding direction, and a typical adhesive wear mechanism is prevalent during the galling process.

  2. Roughness characterization of the galling of metals

    NASA Astrophysics Data System (ADS)

    Hubert, C.; Marteau, J.; Deltombe, R.; Chen, Y. M.; Bigerelle, M.

    2014-09-01

    Several kinds of tests exist to characterize the galling of metals, such as that specified in ASTM Standard G98. While the testing procedure is accurate and robust, the analysis of the specimen's surfaces (area=1.2 cm) for the determination of the critical pressure of galling remains subject to operator judgment. Based on the surface's topography analyses, we propose a methodology to express the probability of galling according to the macroscopic pressure load. After performing galling tests on 304L stainless steel, a two-step segmentation of the S q parameter (root mean square of surface amplitude) computed from local roughness maps (100 μ m× 100 μ m) enables us to distinguish two tribological processes. The first step represents the abrasive wear (erosion) and the second one the adhesive wear (galling). The total areas of both regions are highly relevant to quantify galling and erosion processes. Then, a one-parameter phenomenological model is proposed to objectively determine the evolution of non-galled relative area A e versus the pressure load P, with high accuracy ({{A}e}=100/(1+a{{P}2}) with a={{0.54}+/- 0.07}× {{10}-3} M P{{a}-2} and with {{R}2}=0.98). From this model, the critical pressure of galling is found to be equal to 43MPa. The {{S}5 V} roughness parameter (the five deepest valleys in the galled region's surface) is the most relevant roughness parameter for the quantification of damages in the ‘galling region’. The significant valleys’ depths increase from 10 μm-250 μm when the pressure increases from 11-350 MPa, according to a power law ({{S}5 V}=4.2{{P}0.75}, with {{R}2}=0.93).

  3. 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.

  4. Constraints on the evolution of resistance to gall flies in Solidago altissima: resistance sometimes costs more than it is worth.

    PubMed

    Wise, Michael J; Abrahamson, Warren G

    2017-07-01

    Plant populations frequently maintain submaximal levels of resistance to natural enemies, even in the presence of substantial genetic variation for resistance. Identifying constraints on the evolution of increased resistance has been a major goal of researchers of plant-herbivore interactions. In a glasshouse study, we measured relative costs and benefits of resistance of tall goldenrod (Solidago altissima) to the gall-inducing tephritid Eurosta solidaginis. We exposed multiple ramets of 26 goldenrod genets to nutrient or shade stress and to oviposition by E. solidaginis. The presence of a gall cost a ramet an average of 1743 seeds, but the cost differed 10-fold across environments. Plant genets varied widely for an induced 'hypersensitive' response in which meristem cells become necrotic and kill E. solidaginis hatchlings before gall induction. There was no evidence that this highly effective resistance trait carried an allocation cost. However, the response carried a risk of autotoxicity, as necrosis killed the apex of 37% of the ungalled ramets. On average, a damaged apex cost each ramet 5015 seeds. Autotoxicity may constrain the resistance of S. altissima to an intermediate level, and variation in environmental conditions may alter the relative costs and benefits of resistance and tolerance, thus maintaining genetic variation within goldenrod populations. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. Phytohormones in Japanese mugwort gall induction by a gall-inducing gall midge.

    PubMed

    Tanaka, Yuichiro; Okada, Koichi; Asami, Tadao; Suzuki, Yoshihito

    2013-01-01

    A variety of insect species induce galls on host plants. Liquid chromatographic/tandem mass spectrometric analyses showed that a gall midge (Rhopalomyia yomogicola) that induces galls on Artemisia princeps contained high levels of indole-3-acetic acid and cytokinins. The gall midge larvae also synthesized indole-3-acetic acid from tryptophan. Close observation of gall tissue sections indicated that the larval chamber was surrounded by layers of cells having secondary cell walls with extensive lignin deposition, except for the part of the gall that constituted the feeding nutritive tissue which was composed of small cells negatively stained for lignin. The differences between these two types of tissue were confirmed by an expression analysis of the genes involved in the synthesis of the secondary cell wall. Phytohormones may have functioned in maintaining the feeding part of the gall as fresh nutritive tissue. Together with the results in our previous study, those presented here suggest the importance of phytohormones in gall induction.

  13. 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.

  14. Evaluation of wild juglans species for crown gall resistance

    USDA-ARS?s Scientific Manuscript database

    A. tumefaciens is a soil-borne Gram-negative bacterium which causes crown gall on many dicotyledonous plant species including walnut. Crown gall symptoms on walnut are characterized by large tumors located near the crown of the tree but can occur near wounds caused by bleeding cuts or at the graft u...

  15. 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

  16. 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

  17. 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

    Wear is one of the major causes of artificial total knee arthroplasty (TKA) failure. Wear debris can cause adverse reactions to the surrounding tissue which can ultimately lead to loosening of the prosthesis. The wear behavior of UHMWPE tibial components have been studied extensively, but relatively little attention has been paid to the CoCrMo femoral component. The goal of the present study was to investigate the wear mechanisms of CoCrMo femoral components, to study the effect of CoCrMo alloy surface roughness on the wear of UHMWPE, and to determine the effect of heat treatments on the wear resistance of the CoCrMo implant alloys. The surface roughness of twenty-seven retrieved CoCrMo femoral components was analyzed. A multiple station wear testing machine and a wear fixture attached to an MTS 858 bionix system were built and used for in vitro wear studies of the CoCrMo/UHMWPE bearing couple. Solution and aging treatments were applied to the CoCrMo alloys. A white light interference surface profilometer (WLISP) and a scanning electron microscope (SEM) were used to measure the surface roughness and to study wear mechanisms of CoCrMo alloy. An optical microscope was used for alloy microstructure study. X-ray diffraction tests were performed to identify alloy phase transformation after aging. The micro-structure, hardness, and wear resistance of the alloys were studied. Surface roughness was used to quantify alloy wear, and the minimum number of surface roughness measurements required to obtain a reliable and repeatable characterization of surface roughness for a worn alloy surface was determined. The surfaces of the retrieved CoCrMo femoral components appeared to be damaged by metal particles embedded in the UHMWPE tibial component and metal-on-metal wear due to UHMWPE tibial component through-wear. Surface roughness of the femoral components was not correlated with patient age, weight, sex, or length of implantation. In vitro wear tests showed that when the Co

  18. 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.

  19. Resistance to galling adelgids varies among families of Engelmann spruce (Picea engelmani P.)

    Treesearch

    William J. Mattson; Alvin Yanchuk; Gyula Kiss; Bruce Birr

    1999-01-01

    Cooley gall adelgids, Adelges cooleyi, and round gall adelgids, Adelges abietis, differentially infested 110 half-sib families of Engelmann spruce, Picea engelmannii at 9 study sites in British Columbia. There was a negative genetic correlation (-0.53) between the infestations of the two gall-forming species....

  20. [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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. Gall midges (Hessian flies) as plant pathogens.

    PubMed

    Stuart, Jeff J; Chen, Ming-Shun; Shukle, Richard; Harris, Marion O

    2012-01-01

    Gall midges constitute an important group of plant-parasitic insects. The Hessian fly (HF; Mayetiola destructor), the most investigated gall midge, was the first insect hypothesized to have a gene-for-gene interaction with its host plant, wheat (Triticum spp.). Recent investigations support that hypothesis. The minute larval mandibles appear to act in a manner that is analogous to nematode stylets and the haustoria of filamentous plant pathogens. Putative effector proteins are encoded by hundreds of genes and expressed in the HF larval salivary gland. Cultivar-specific resistance (R) genes mediate a highly localized plant reaction that prevents the survival of avirulent HF larvae. Fine-scale mapping of HF avirulence (Avr) genes provides further evidence of effector-triggered immunity (ETI) against HF in wheat. Taken together, these discoveries suggest that the HF, and other gall midges, may be considered biotrophic, or hemibiotrophic, plant pathogens, and they demonstrate the potential that the wheat-HF interaction has in the study of insect-induced plant gall formation.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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.

  13. Effects of nutrient treatment and previous stem galling on biomass allocation in tall goldenrod, Solidago altissima

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

    Anderson, S.S.; Abrahamson, W.G.; McCrea, K.D.

    1987-07-01

    Ramets from six goldenrod clones of known resistance to the gallmaker (Eurosta solidaginis) were grown with and without nutrient treatment. Mated female Eurosta oviposited in ramets which were grown through flowering and harvested to determine biomass allocation. Nutrient treatment increased biomass but did not affect resistance. Gall mass was increased by nutrient treatment and was correlated with larval mass. Additional ramets from two of the susceptible clones were grown from rhizomes of ramets galled and ungalled the previous year. Galls reduced ramet growth in both years. A gall in the previous year reduced total ramet biomass as well as biomassmore » of all component organs in the current year but a gall in the current season had no effect. The detrimental effects of a gall are carried into the next growing season.« less

  14. 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.

  15. Arthropods associated with fungal galls: do large galls support more abundant and diverse inhabitants?

    NASA Astrophysics Data System (ADS)

    Funamoto, Daichi; Sugiura, Shinji

    2017-02-01

    Fungus-induced galls can attract spore-feeding arthropods as well as gall-feeding ones, resulting in diverse communities. Do large fungal galls support more abundant and diverse arthropod communities than small fungal galls? To address this question, we investigated the structure of the arthropod community associated with bud galls induced by the fungus Melanopsichium onumae on the tree species Cinnamomum yabunikkei (Lauraceae) in central Japan. Thirteen species of arthropods were associated with M. onumae galls. Dominant arthropod species were represented by the larvae of a salpingid beetle (a spore feeder), a nitidulid beetle (a spore feeder), a cosmopterigid moth (a spore feeder), an unidentified moth (a gall tissue feeder), and a drosophilid species (a gall tissue feeder). Arthropod abundance and species richness were positively correlated with gall diameter. The majority of the most abundant species were more frequently found in large galls than in small ones, indicating that large fungal galls, which have more food and/or space for arthropods, could support a more abundant and diverse arthropod community.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  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. 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.

  5. 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

  6. 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.

  7. Evaluation of wild Juglans species for crown gall resistance

    USDA-ARS?s Scientific Manuscript database

    Paradox, the most widely used rootstock in CA walnut production, is highly susceptible to the causal agent of crown gall (CG) Agrobacterium tumefaciens. The bacterial pathogen induces the formation of large tumors around the crown of the tree resulting in a reduction in both vigor and yield. If left...

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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...

  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. Nucleation time of gall bladder bile in gall stone patients: influence of bile acid treatment.

    PubMed Central

    Sahlin, S; Ahlberg, J; Angelin, B; Reihnér, E; Einarsson, K

    1991-01-01

    The time required for precipitation of cholesterol crystals (nucleation time, NT) was determined and related to the cholesterol saturation in gall bladder bile of gall stone free subjects (n = 11), patients with pigment stones (n = 3), and patients with cholesterol gall stones (n = 30) undergoing cholecystectomy. Seven of the gall stone patients had been treated with chenodeoxycholic acid (CDCA) and nine with ursodeoxycholic acid (UDCA), 15 mg/kg/day for three weeks before operation. NT was longer in gall stone free subjects (mean, 20 days), patients with pigment stones (14 days) and patients treated with CDCA (24 days) and UDCA (17 days) compared with untreated patients with cholesterol gall stones (1.5 days). In spite of low cholesterol saturation and prolonged NT, and in contrast to those treated with CDCA, four of the nine patients treated with UDCA had cholesterol crystals in their bile. These observations give further support to the concept that the mechanism for inducing gall stone dissolution may be different for CDCA and UDCA. PMID:1773966

  15. Resistance of chestnut trees to Asia chestnut gall wasp

    Treesearch

    S. Anagnostakis; S.L. Clark; H. McNab

    2011-01-01

    Asian chestnut gall wasp (Dryocosmus kuriphihus) was introduced into Georgia (USA) in 1975 and has been spreading north throughout the range of American chestnut (Castanea dentate). This pest is now present throughout most of Tennessee. In 2003, it was found near Cleveland, Ohio and has been spreading south from there. In 1995, hybrid chestnuts with C. dentate female...

  16. 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

  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. 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.

  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. 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

  2. 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

  3. Fungus-insect gall of Phlebopus portentosus.

    PubMed

    Zhang, Chun-Xia; He, Ming-Xia; Cao, Yang; Liu, Jing; Gao, Feng; Wang, Wen-Bing; Ji, Kai-Ping; Shao, Shi-Cheng; Wang, Yun

    2015-01-01

    Phlebopus portentosus is a popular edible wild mushroom found in the tropical Yunnan, China, and northern Thailand. In its natural habitats, a gall often has been found on some plant roots, around which fungal fruiting bodies are produced. The galls are different from common insect galls in that their cavity walls are not made from plant tissue but rather from the hyphae of P. portentosus. Therefore we have termed this phenomenon "fungus-insect gall". Thus far six root mealy bug species in the family Pseudococcidae that form fungus-insect galls with P. portentosus have been identified: Formicococcus polysperes, Geococcus satellitum, Planococcus minor, Pseudococcus cryptus, Paraputo banzigeri and Rastrococcus invadens. Fungus-insect galls were found on the roots of more than 21 plant species, including Delonix regia, Citrus maxima, Coffea arabica and Artocarpus heterophyllus. Greenhouse inoculation trials showed that fungus-insect galls were found on the roots of A. heterophyllus 1 mo after inoculation. The galls were subglobose to globose, fulvous when young and became dark brown at maturation. Each gall harbored one or more mealy bugs and had a chimney-like vent for ventilation and access to the gall. The cavity wall had three layers. Various shaped mealy bug wax deposits were found inside the wall. Fungal hyphae invaded the epidermis of plant roots and sometimes even the cortical cells during the late stage of gall development. The identity of the fungus inside the cavity was confirmed by molecular methods. © 2015 by The Mycological Society of America.

  4. 77 FR 73654 - Eau Galle Renewable Energy Company, Eau Galle Hydro, LLC; Notice of Transfer of Exemption

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-11

    ... Renewable Energy Company, Eau Galle Hydro, LLC; Notice of Transfer of Exemption 1. By letter filed October 12, 2012, Eau Galle Renewable Energy Company informed the Commission that its exemption from... transferred to Eau Galle Renewable Energy Company by letter.\\2\\ The project is located on the Eau Galle River...

  5. 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.

  6. Regional differences in constituents of gall stones.

    PubMed

    Ashok, M; Nageshwar Reddy, D; Jayanthi, V; Kalkura, S N; Vijayan, V; Gokulakrishnan, S; Nair, K G M

    2005-01-01

    The pathogenesis of pigment and mixed gall stone formation remains elusive. The elemental constituents of gall stones from southern states of Tamil Nadu, Kerala and Karnataka have been characterized. Our aim was to determine the elemental concentration of representative samples of pigment, mixed and cholesterol gall stones from Andhra Pradesh using proton-induced X-ray emission (PIXE) using a 3 MV horizontal pelletron accelerator. Pigment gall stones had significantly high concentrations of copper, iron and lead; chromium was absent. Except for iron all these elements were significantly low in cholesterol gall stones and intermediate levels were seen in mixed gall stones. Highest concentrations of chromium was seen in cholesterol and titanium in mixed gall stones respectively; latter similar to other southern states. Arsenic was distinctly absent in cholesterol and mixed gall stones. The study has identified differences in elemental components of the gall stones from Andhra Pradesh.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. Duplex gall bladder: bystander or culprit.

    PubMed

    Kumar, Jogender; Yadav, Arushi

    2017-08-30

    Gall bladder (GB) duplication is a rare anatomical malformation, which can be detected by preoperative imaging study. We present a case of duplex gall bladder in a 14-year-old boy who presented with abdominal pain. On ultrasound, he had right nephrolithiasis and duplex gall bladder. Duplex gall bladder was confirmed on MR cholangiopancreatography. There was a dilemma for surgical management of duplex gall bladder; however, he became asymptomatic after conservative treatment. Prophylactic surgery is not recommended for asymptomatic incidentally detected duplex gall bladder. Radiologists and paediatric surgeons should be sensitised about the exact anatomy of this entity. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. [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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. The gall wasp Leptocybe invasa (Hymenoptera: Eulophidae) stimulates different chemical and phytohormone responses in two Eucalyptus varieties that vary in susceptibility to galling.

    PubMed

    Li, X Q; Liu, Y Z; Guo, W F; Solanki, M K; Yang, Z D; Xiang, Y; Ma, Z C; Wen, Y G

    2017-09-01

    Gall-inducing insects produce various types of galls on plants, but little is known about the gall-induction mechanism of these galling insects. The gall wasp Leptocybe invasa Fisher & LaSalle (Hymenoptera: Eulophidae) forms galls of different sizes on several Eucalyptus species. To clarify the physiological responses of Eucalyptus to L. invasa infestation, we measured the dynamics of nitrogen (N), carbon (C), total phenolics, total tannins and four types of phytohormones (zeatin [Z] + zeatin riboside [ZR], gibberellins [GA], indole-3-acetic acid [IAA] and abscisic acid [ABA]) in galled and ungalled leaf tissues of two Eucalyptus horticultural varieties (DH201-2 [Eucalyptus grandis × Eucalyptus camaldulensis] and EA [Eucalyptus exserta]) with different susceptibility to galling throughout the larval developmental stages. Nitrogen, total phenolics, tannins and four kinds of phytohormones strongly accumulated in tissues galled by L. invasa (especially during early larval feeding stages). While N, Z + ZR and GA levels were higher, tannins and ABA levels were lower in the galled tissues on the highly susceptible variety. Nitrogen, total phenolics, GA, Z + ZR and IAA levels in the galled tissues gradually decreased during gall development, but ABA and tannins conversely increased in the galled tissues of the less susceptible variety. Our results suggest that the effects of gall-inducing insects on plants depend not only on the susceptibility of the plant infested but also on the developmental stage of galled tissues. Gall formation process is thus synergistically influenced by both gall-inducing insect and plant genotypes. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. Bringing the Outside In: Insects and Their Galls.

    ERIC Educational Resources Information Center

    Farenga, Stephen J.; Joyce, Beverly A.; Ness, Daniel; Wilkens, Richard

    2003-01-01

    Introduces gall-making insects and explains gall development. Explains how to bring galls into the classroom and conduct experiments. Suggests using gall systems to introduce students to the concepts of genetic control, biodiversity, plant and animal development, species interactions, biodiversity, and the flow of energy through the food web. (YDS)

  17. Phylogeny, evolution, and classification of gall wasps: the plot thickens

    USDA-ARS?s Scientific Manuscript database

    Gall wasps (Cynipidae) represent the most spectacular radiation of gall-inducing insects. In addition to true gall formers, gall wasps also include phytophagous inquilines, which live inside the galls induced by gall wasps or other insects. Here we present the first comprehensive molecular and total...

  18. Phylogenetics of Australasian gall flies (Diptera: Fergusoninidae): Evolutionary patterns of host-shifting and gall morphology.

    PubMed

    Scheffer, S J; Davies, K A; Taylor, G S; Thornhill, A H; Lewis, M L; Winkler, I S; Yeates, D K; Purcell, M F; Makinson, J; Giblin-Davis, R M

    2017-10-01

    This study investigated host-specificity and phylogenetic relationships in Australian galling flies, Fergusonina Malloch (Diptera: Fergusoninidae), in order to assess diversity and explore the evolutionary history of host plant affiliation and gall morphology. A DNA barcoding approach using COI data from 203 Fergusonina specimens from 5gall types on 56 host plant species indicated 85 presumptive fly species. These exhibited a high degree of host specificity; of the 40 species with multiple representatives, each fed only on a single host genus, 29 (72.5%) were strictly monophagous, and 11 (27.5%) were reared from multiple closely related hosts. COI variation within species was not correlated with either sample size or geographic distance. However variation was greater within oligophagous species, consistent with expectations of the initial stages of host-associated divergence during speciation. Phylogenetic analysis using both nuclear and mitochondrial genes revealed host genus-restricted clades but also clear evidence of multiple colonizations of both host plant genus and host species. With the exception of unilocular peagalls, evolution of gall type was somewhat constrained, but to a lesser degree than host plant association. Unilocular peagalls arose more often than any other gall type, were primarily located at the tips of the phylogeny, and did not form clades comprising more than a few species. For ecological reasons, species of this gall type are predicted to harbor substantially less genetic variation than others, possibly reducing evolutionary flexibility resulting in reduced diversification in unilocular gallers. Published by Elsevier Inc.

  19. 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.

  20. 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.

  1. 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.

  2. Evaluation of wild walnut Juglans spp. for resistance to crown gall disease

    USDA-ARS?s Scientific Manuscript database

    Crown gall (CG) disease of walnut is caused by the ubiquitous soil-borne bacterium, Agrobacterium tumefaciens. The most widely used rootstock Paradox, an interspecific hybrid between Juglans hindsii and Juglans regia, is typically highly susceptible to A. tumefaciens. Identification of a durable sou...

  3. Manipulation of host plant cells and tissues by gall-inducing insects and adaptive strategies used by different feeding guilds.

    PubMed

    Oliveira, D C; Isaias, R M S; Fernandes, G W; Ferreira, B G; Carneiro, R G S; Fuzaro, L

    2016-01-01

    Biologists who study insect-induced plant galls are faced with the overwhelming diversity of plant forms and insect species. A challenge is to find common themes amidst this diversity. We discuss common themes that have emerged from our cytological and histochemical studies of diverse neotropical insect-induced galls. Gall initiation begins with recognition of reactive plant tissues by gall inducers, with subsequent feeding and/or oviposition triggering a cascade of events. Besides, to induce the gall structure insects have to synchronize their life cycle with plant host phenology. We predict that reactive oxygen species (ROS) play a role in gall induction, development and histochemical gradient formation. Controlled levels of ROS mediate the accumulation of (poly)phenols, and phytohormones (such as auxin) at gall sites, which contributes to the new cell developmental pathways and biochemical alterations that lead to gall formation. The classical idea of an insect-induced gall is a chamber lined with a nutritive tissue that is occupied by an insect that directly harvests nutrients from nutritive cells via its mouthparts, which function mechanically and/or as a delivery system for salivary secretions. By studying diverse gall-inducing insects we have discovered that insects with needle-like sucking mouthparts may also induce a nutritive tissue, whose nutrients are indirectly harvested as the gall-inducing insects feeds on adjacent vascular tissues. Activity of carbohydrate-related enzymes across diverse galls corroborates this hypothesis. Our research points to the importance of cytological and histochemical studies for elucidating mechanisms of induced susceptibility and induced resistance. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. 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

  5. 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.

  6. 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...

  7. Phylogeny, Evolution and Classification of Gall Wasps: The Plot Thickens

    PubMed Central

    Ronquist, Fredrik; Nieves-Aldrey, José-Luis; Buffington, Matthew L.; Liu, Zhiwei; Liljeblad, Johan; Nylander, Johan A. A.

    2015-01-01

    Gall wasps (Cynipidae) represent the most spectacular radiation of gall-inducing insects. In addition to true gall formers, gall wasps also include phytophagous inquilines, which live inside the galls induced by gall wasps or other insects. Here we present the first comprehensive molecular and total-evidence analyses of higher-level gall wasp relationships. We studied more than 100 taxa representing a rich selection of outgroups and the majority of described cynipid genera outside the diverse oak gall wasps (Cynipini), which were more sparsely sampled. About 5 kb of nucleotide data from one mitochondrial (COI) and four nuclear (28S, LWRh, EF1alpha F1, and EF1alpha F2) markers were analyzed separately and in combination with morphological and life-history data. According to previous morphology-based studies, gall wasps evolved in the Northern Hemisphere and were initially herb gallers. Inquilines originated once from gall inducers that lost the ability to initiate galls. Our results, albeit not conclusive, suggest a different scenario. The first gall wasps were more likely associated with woody host plants, and there must have been multiple origins of gall inducers, inquilines or both. One possibility is that gall inducers arose independently from inquilines in several lineages. Except for these surprising results, our analyses are largely consistent with previous studies. They confirm that gall wasps are conservative in their host-plant preferences, and that herb-galling lineages have radiated repeatedly onto the same set of unrelated host plants. We propose a revised classification of the family into twelve tribes, which are strongly supported as monophyletic across independent datasets. Four are new: Aulacideini, Phanacidini, Diastrophini and Ceroptresini. We present a key to the tribes and discuss their morphological and biological diversity. Until the relationships among the tribes are resolved, the origin and early evolution of gall wasps will remain elusive

  8. 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.

  9. 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.

  10. 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

  11. 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.

  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. 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.

  14. 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.

  15. 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

  16. 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.

  17. Galle Crater

    NASA Image and Video Library

    2002-06-26

    This image from NASA Mars Odyssey spacecraft shows part of Galle Crater. It was taken far enough south and late enough into the southern hemisphere fall to observe water ice clouds partially obscuring the surface.

  18. 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.

  19. 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.

  20. Galls and gall makers in plants from the Pé-de-Gigante Cerrado Reserve, Santa Rita do Passa Quatro, SP, Brazil.

    PubMed

    Urso-Guimarães, M V; Scareli-Santos, C

    2006-02-01

    Thirty-six morphologically different types of galls were obtained in leaves, leaflets, veins, petioles, stems, tendrils and flower buds from twenty-five species of plants in the Pé-de-Gigante Reserve, municipality of Santa Rita do Passa Quatro, state of São Paulo, Brazil. The host plant species belong to the closely related families Anacardiaceae, Annonaceae, Asteraceae, Bignoniaceae, Caryocaraceae, Erythroxylaceae, Fabaceae, Malpighiaceae, Melastomataceae, Myrtaceae, Ochnaceae, Polygalaceae, Sapindaceae, Sapotaceae, and Smilacaceae. The most common gall makers included Cecidomyiidae (Diptera), Pteromalidae (Hymenoptera) and Diaspididae (Sternorrhyncha-Hemiptera). This is the first report of galls found in the following plant genera: Gochnatia (Asteraceae), Distictela (Bignoniaceae), Banisteriopsis (Malpighiaceae), Ouratea (Ochnaceae), and Bredemeyera (Polygalaceae). The results of this work contribute to the body of knowledge about the relationship among host plants, gall makers, and the gall morphology of Pé-de-Gigante Cerrado Reserve.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Reflections on the Gall-Peters Projection.

    ERIC Educational Resources Information Center

    Robinson, Arthur H.

    1987-01-01

    Explains the cartographic qualities of rectangular world maps and compares the merits of various projections such as the Mercator and the recently-created Gall-Peters. States that the Gall-Peters projection does not provide a reasonable base for a general world map; that no rectangular projection does. (JDH)

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Caterpillar mimicry by plant galls as a visual defense against herbivores.

    PubMed

    Yamazaki, Kazuo

    2016-09-07

    Plant galls, induced by arthropods and various other organisms have an intimate relationship with host plants, and gall-inducers have limited mobility. In addition to their own photosynthesis, galls are resource sinks rich with nutrients, with neighboring plant organs commonly serving as external photosynthate sources. Galls, if not well defended, may therefore be attractive food sources for herbivores. Galls produced by some aphids, jumping plant lice, thrips, and gall midges in Japan, Palearctic region and in the Middle East visually resemble lepidopteran caterpillars. I propose that such visual resemblance may reduce herbivory of galls and surrounding plant tissues, resulting in an increase in galler survival due to reduced gall damage and in enhanced galler growth due to improved nutrient inflow to the galls, when herbivores avoid colonizing or consuming plant parts that look as if they have been occupied by other herbivores. Potential predators and parasitoids of caterpillars may be attracted to the caterpillar-like galls and then attack real caterpillars and other invertebrate herbivores, which would also be beneficial for both gallers and their hosts. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. The biology of gall-inducing arthropods.

    Treesearch

    Gyuri Csoka; William J. Mattson; Graham N. Stone; Peter W. Price

    1998-01-01

    This proceedings explores many facets of the ever intriguing and enigmatic relationships between plants and their gall-forming herbivores. The research reported herein ranges from studies on classical biology and systematics of galling to molecular phylogeny, population genetics, and ecological and evolutionary theory. Human kind has much to learn and gain from...

  19. 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

  20. Phenotypic plasticity and similarity among gall morphotypes on a superhost, Baccharis reticularia (Asteraceae).

    PubMed

    Formiga, A T; Silveira, F A O; Fernandes, G W; Isaias, R M S

    2015-03-01

    Understanding factors that modulate plant development is still a challenging task in plant biology. Although research has highlighted the role of abiotic and biotic factors in determining final plant structure, we know little of how these factors combine to produce specific developmental patterns. Here, we studied patterns of cell and tissue organisation in galled and non-galled organs of Baccharis reticularia, a Neotropical shrub that hosts over ten species of galling insects. We employed qualitative and quantitative approaches to understand patterns of growth and differentiation in its four most abundant gall morphotypes. We compared two leaf galls induced by sap-sucking Hemiptera and stem galls induced by a Lepidopteran and a Dipteran, Cecidomyiidae. The hypotheses tested were: (i) the more complex the galls, the more distinct they are from their non-galled host; (ii) galls induced on less plastic host organs, e.g. stems, develop under more morphogenetic constraints and, therefore, should be more similar among themselves than galls induced on more plastic organs. We also evaluated the plant sex preference of gall-inducing insects for oviposition. Simple galls were qualitative and quantitatively more similar to non-galled organs than complex galls, thereby supporting the first hypothesis. Unexpectedly, stem galls had more similarities between them than to their host organ, hence only partially supporting the second hypothesis. Similarity among stem galls may be caused by the restrictive pattern of host stems. The opposite trend was observed for host leaves, which generate either similar or distinct gall morphotypes due to their higher phenotypic plasticity. The Relative Distance of Plasticity Index for non-galled stems and stem galls ranged from 0.02 to 0.42. Our results strongly suggest that both tissue plasticity and gall inducer identity interact to determine plant developmental patterns, and therefore, final gall structure. © 2014 German Botanical Society

  1. 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.

  2. 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.

  3. Distinct antimicrobial activities in aphid galls on Pistacia atlantica

    PubMed Central

    Yoram, Gerchman; Inbar, Moseh

    2011-01-01

    Gall-formers are parasitic organisms that manipulate plant traits for their own benefit. Galls have been shown to protect their inhabitants from natural enemies such as predators and parasitoids by various chemical and mechanical means. Much less attention, however, has been given to the possibility of defense against microbial pathogens in the humid and nutrient-rich gall environment. We found that the large, cauliflower-shaped, galls induced by the aphid Slavum wertheimae on buds of Pistacia atlantica trees express antibacterial and antifungal activities distinct from those found in leaves. Antibacterial activity was especially profound against Bacillus spp (a genus of many known insect pathogen) and against Pseudomonas aeruginosa (a known plant pathogen). Antifungal activity was also demonstrated against multiple filamentous fungi. Our results provide evidence for the protective antimicrobial role of galls. This remarkable antibacterial and antifungal activity in the galls of S. wertheimae may be of agricultural and pharmaceutical value. PMID:22105034

  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. Gall-induction in insects: evolutionary dead-end or speciation driver?

    PubMed Central

    2010-01-01

    Background The tree of life is significantly asymmetrical - a result of differential speciation and extinction - but general causes of such asymmetry are unclear. Differences in niche partitioning are thought to be one possible general explanation. Ecological specialization might lead to increases in diversification rate or, alternatively, specialization might limit the evolutionary potential of specialist lineages and increase their extinction risk. Here we compare the diversification rates of gall-inducing and non-galling insect lineages. Compared with other insect herbivores feeding on the same host plant, gall-inducing insects feed on plant tissue that is more nutritious and less defended, and they do so in a favorable microhabitat that may also provide some protection from natural enemies. We use sister-taxon comparisons to test whether gall-inducing lineages are more host-specific than non-galling lineages, and more or less diverse than non-gallers. We evaluate the significance of diversity bipartitions under Equal Rates Markov models, and use maximum likelihood model-fitting to test for shifts in diversification rates. Results We find that, although gall-inducing insect groups are more host-specific than their non-galling relatives, there is no general significant increase in diversification rate in gallers. However, gallers are found at both extremes - two gall-inducing lineages are exceptionally diverse (Euurina sawflies on Salicaceae and Apiomorpha scale insects on Eucalytpus), and one gall-inducing lineage is exceptionally species-poor (Maskellia armored scales on Eucalyptus). Conclusions The effect of ecological specialization on diversification rates is complex in the case of gall-inducing insects, but host range may be an important factor. When a gall-inducing lineage has a host range approximate to that of its non-galling sister, the gallers are more diverse. When the non-galler clade has a much wider host range than the galler, the non-galler is

  6. Taxonomy and biology of a new ambrosia gall midge Daphnephila urnicola sp. nov. (Diptera: Cecidomyiidae) inducing urn-shaped leaf galls on two species of Machilus (Lauraceae) in Taiwan.

    PubMed

    Pan, Liang-Yu; Chiang, Tung-Chuan; Weng, Yu-Chu; Chen, Wen-Neng; Hsiao, Shu-Chuan; Tokuda, Makoto; Tsai, Cheng-Lung; Yang, Man-Miao

    2015-05-05

    Recent field surveys show that galls induced by Daphnephila spp. (Cecidomyiidae) on Machilus spp. (Lauraceae) are common in Taiwan, yet only five species, four leaf-gall inducers and one stem-gall inducer on M. thunbergii, have been named in the past. Here we describe a new species, Daphnephila urnicola sp. nov. Chiang, Yang & Tokuda, inducing urn-shaped galls on leaves of both M. zuihoensis and M. mushaensis. Comparisons of D. urnicola populations on M. zuihoensis and on M. mushaensis, indicate that they belong to one species, a result supported by gall midge morphology, life-history traits, gall shape and structure, the developmental process of gall tissues, fungal associations, and DNA-sequencing data. Size and structure of the gall operculum was found to differ between M. zuihoensis and M. mushahaensis.

  7. 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.

  8. Fungal endophytes which invade insect galls: insect pathogens, benign saprophytes, or fungal inquilines?

    PubMed

    Wilson, Dennis

    1995-08-01

    Fungi are frequently found within insect galls. However, the origin of these fungi, whether they are acting as pathogens, saprophytes invading already dead galls, or fungal inquilines which invade the gall but kill the gall maker by indirect means, is rarely investigated. A pathogenic role for these fungi is usually inferred but never tested. I chose the following leaf-galling-insect/host-plant pairs (1) a cynipid which forms two-chambered galls on the veins of Oregon white oak, (2) a cynipid which forms single-chambered galls on California coast live oak, and (3) an aphid which forms galls on narrowleaf cottonwood leaves. All pairs were reported to have fungi associated with dead insects inside the gall. These fungi were cultured and identified. For the two cynipids, all fungi found inside the galls were also present in the leaves as fungal endophytes. The cottonwood leaves examined did not harbor fungal endophytes. For the cynipid on Oregon white oak, the fungal endophyte grows from the leaf into the gall and infects all gall tissue but does not directly kill the gall maker. The insect dies as a result of the gall tissue dying from fungal infection. Therefore, the fungus acts as an inquiline. Approximately 12.5% of these galls die as a result of invasion by the fungal endophyte.

  9. 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

  10. Pathfinder Atomic Power Plant Nozzle Galling Test, Final Report

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

    None, None

    1961-12-29

    Galling tests of 304, 17-4PH, and chrome-plated 304 stainless-steel nozzles with 304 stainless-steel sleeves were conducted at Pathflnder reactor conditions of 480 deg F, 600 psig. A horizontal force was imposed on the sleeve with the nozzle inserted; and the nozzle was moved axially to determine galling tendencies. Galling was produced on both the 304 and 17-4PH stainless-steel nozzles. The chrome-plated 304-stainless-steel nozzles were cycled numerous times without galling. On the basis of these tests, chrome-plated 304-stainless- steel is the material selected for the Pathfinder boiler fuel-element nozzle.

  11. Sugary secretions of wasp galls: a want-to-be extrafloral nectar?

    PubMed

    Aranda-Rickert, Adriana; Rothen, Carolina; Diez, Patricia; González, Ana María; Marazzi, Brigitte

    2017-11-10

    The most widespread form of protective mutualisms is represented by plants bearing extrafloral nectaries (EFNs) that attract ants and other arthropods for indirect defence. Another, but less common, form of sugary secretion for indirect defence occurs in galls induced by cynipid wasps. Until now, such galls have been reported only for cynipid wasps that infest oak trees in the northern hemisphere. This study provides the first evidence of galls that exude sugary secretions in the southern hemisphere and asks whether they can be considered as analogues of plants' EFNs. The ecology and anatomy of galls and the chemical composition of the secretion were investigated in north-western Argentina, in natural populations of the host trees Prosopis chilensis and P. flexuosa . To examine whether ants protect the galls from natural enemies, ant exclusion experiments were conducted in the field. The galls produce large amounts of sucrose-rich, nectar-like secretions. No typical nectary and sub-nectary parenchymatic tissues or secretory trichomes can be observed; instead there is a dense vascularization with phloem elements reaching the gall periphery. At least six species of ants, but also vespid wasps, Diptera and Coleoptera, consumed the gall secretions. The ant exclusion experiment showed that when ants tended galls, no differences were found in the rate of successful emergence of gall wasps or in the rate of parasitism and inquiline infestation compared with ant-excluded galls. The gall sugary secretion is not analogous to extrafloral nectar because no nectar-producing structure is associated with it, but is functionally equivalent to arthropod honeydew because it provides indirect defence to the plant parasite. As in other facultative mutualisms mediated by sugary secretions, the gall secretion triggers a complex multispecies interaction, in which the outcome of individual pair-wise interactions depends on the ecological context in which they take place. © The Author

  12. Gall volatiles defend aphids against a browsing mammal

    PubMed Central

    2013-01-01

    Background Plants have evolved an astonishing array of survival strategies. To defend against insects, for example, damaged plants emit volatile organic compounds that attract the herbivore’s natural enemies. So far, plant volatile responses have been studied extensively in conjunction with leaf chewing and sap sucking insects, yet little is known about the relationship between plant volatiles and gall-inducers, the most sophisticated herbivores. Here we describe a new role for volatiles as gall-insects were found to benefit from this plant defence. Results Chemical analyses of galls triggered by the gregarious aphid Slavum wertheimae on wild pistachio trees showed that these structures contained and emitted considerably higher quantities of plant terpenes than neighbouring leaves and fruits. Behavioural assays using goats as a generalist herbivore confirmed that the accumulated terpenes acted as olfactory signals and feeding deterrents, thus enabling the gall-inducers to escape from inadvertent predation by mammals. Conclusions Increased emission of plant volatiles in response to insect activity is commonly looked upon as a “cry for help” by the plant to attract the insect’s natural enemies. In contrast, we show that such volatiles can serve as a first line of insect defences that extends the ‘extended phenotype’ represented by galls, beyond physical boundaries. Our data support the Enemy hypothesis insofar that high levels of gall secondary metabolites confer protection against natural enemies. PMID:24020365

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. Insect galls of Restinga de Marambaia (Barra de Guaratiba, Rio de Janeiro, RJ).

    PubMed

    Maia, V C; Silva, L O

    2016-04-19

    Thirty-one morphotypes of insect galls and two flower damages were found on 16 families, 22 genera and 24 plant species in Restinga de Marambaia (Barra de Guaratiba, Rio de Janeiro, RJ). Fabaceae and Myrtaceae were the plant families with the greatest richness of insect galls (4 and 6 morphotypes, respectively), and the greatest number of galled plants (four and three species, respectively). Galls were mostly found on leaves and stems (77% and 10%, respectively). The galling insects are represented by Diptera, Lepidoptera, and Hemiptera. The majority of the galls (81%) were induced by gall midges (Cecidomyiidae: Diptera).

  2. 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.

  3. 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%).

  4. 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

  5. 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.

  6. 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.

  7. Gall midges (Diptera: Cecidomyiidae) in forest ecosystems

    Treesearch

    Marcela Skuhrav& #225; ; Marcela NO-VALUE

    1991-01-01

    The family Cecidomyiidae is one of the largest of the Diptera. Gall midges are small, inconspicuous flies, but they may be very important both in forest ecosystems and in agroecosystems. Many phytophagous gall midge species attack forest trees, and some of them can be serious pests, such as the Dasineura rozhkovii Mamaev and Nikolsky, which develops...

  8. 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

  9. 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.

  10. 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

  11. Significance of phytohormones in Siberian larch-bud gall midge interaction

    Treesearch

    Rida M. Matrenina

    1991-01-01

    Interrelations of the bud gall midge and the Siberian larch are of scientific and practical interest because of the bud gall midge's role as a plant endoparasite. We know that attack by the gall midge sets off a reaction in the entire plant. Invasion by the insect results in a certain interaction between physiological mechanisms of the insect and the plant which...

  12. Antioxidant activity of insect gall extracts of Pistacia integerrima.

    PubMed

    Eshwarappa, Ravi Shankara Birur; Lakshmikantha, Ramachandra Yarappa; Subaramaihha, Sundara Rajan; Subbaiah, Sujan Ganapathy Pasura; Surendranath, Austin Richard; Dhananjaya, Bhadrapura Lakkappa

    2015-01-01

    Pistacia integerrima (P. integerrina) insect galls are widely used in ayurveda and siddha system of medicine as karkatasringi. The use of leaf galls as a rejuvenator may be attributed to antioxidant property, however there is less scientific evidence. Therefore, the aim of this study was to evaluate the chemical composition and the antioxidant potential of leaf gall extracts (aqueous and ethanol) of P. integerrina, which is extensively used in the preparation of traditional medications. The antioxidant activities of aqueous and ethanolic leaf gall extracts were examined using diphenylpicrylhydrazyl (DPPH), hydroxyl scavenging and ferric reducing power (FRAP) methods. The presences of phenolics, tannins, phytosterols, triterpenoids, saponins, flavonoids and reducing sugars were identified in both the extracts. In comparison to the aqueous extract, the ethanolic extract had the highest total phenolic and flavonoid content at 234 ±2.4 mg of GAE/g d.w. and 95.5 ±3.2 mg of QUE/g d.w., respectively. This higher content of total phenolics and flavonoids found in the ethanolic extract was directly associated with higher antioxidant activity. This study demonstrates the poetnet antioxidant activities of P. integerrima leaf gall extracts. Further, there was a strong association between the higher antioxidant activities with that of higher total phenolic and flavonoid content in the ethanolic leaf gall extracts of P. integerrima. The results encourage the use of P. integerrima leaf gall extracts for medicinal health, functional food and nutraceuticals applications, due to their antioxidant properties. Future work will be interesting to learn the chemical composition and better understand the mechanism of action of the antioxidants present in the extract for development as a drug for therapeutic application.

  13. 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

  14. Preliminary report on the segregation of resistance in chestnuts to infestation by oriental chestnut gall wasp

    Treesearch

    S Anagnostakis; Stacy Clark; Henry Mcnab

    2009-01-01

    In 1995, hybrid chestnuts were planted in North Carolina, (southern U.S.A.),where the introduced insect Oriental Chestnut Gall Wasp (Dryocosmus kuriphilus) ispresent. Of the 93 trees planted, 53 survived 12 years and were evaluated for the

  15. 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...

  16. 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.

  17. 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.

  18. 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.

  19. Diversity of insect galls associated with coastal shrub vegetation in Rio de Janeiro, Brazil.

    PubMed

    Carvalho-Fernandes, Sheila P; Ascendino, Sharlene; Maia, Valéria C; Couri, Márcia S

    2016-09-01

    Surveys in the coastal sandy plains (restingas) of Rio de Janeiro have shown a great richness of galls. We investigated the galling insects in two preserved restingas areas of Rio de Janeiro state: Parque Estadual da Costa do Sol and Reserva Particular do Patrimônio Natural Fazenda Caruara. The collections were done each two months, from June 2011 to May 2012. We investigated 38 points during 45 minutes each per collection. The galls were taken to the laboratory for rearing the insects. A total number of 151 insect galls were found in 82 plant species distributed into 34 botanic families. Most of the galls occurred on leaves and the plant families with the highest richness of galls were Myrtaceae and Fabaceae. All the six insect orders with galling species were found in this survey, where Cecidomyiidae (Diptera) was the main galler group. Hymenoptera and Thysanoptera were found as parasitoids and inquilines in 29 galls. The richness of galls in the surveyed areas reveals the importance of restinga for the composition and diversity of gall-inducing insect fauna.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Spatial variation in pollinator gall failure within figs of the gynodioecious Ficus hirta

    NASA Astrophysics Data System (ADS)

    Yu, Hui; Compton, Stephen G.; Wu, Lanfen

    2018-07-01

    Figs, the inflorescences of Ficus species (Moraceae), contain numerous uni-ovulate flowers. Male trees of gynodioecious Ficus have figs that support development of pollinator fig wasp offspring (Agaonidae) and rarely produce seeds. Pollinator larvae develop inside galled ovules that expand rapidly after eggs are laid to fill the available space. Galls that fail to support successful larval development can be abundant and failures may influence oviposition behavior and modify realized offspring sex ratios. We examined pollinator reproductive success in figs of the Asian Ficus hirta where we had allowed entry by either one or two foundresses and prevented attack by parasitoids. At the developmental stage when adult offspring were about to emerge from their galls, we recorded where in the figs their galls were located, the distributions of sons and daughters in the galls and whether galls that developed closest to the periphery of the figs were more likely to fail. Foundress number had an effect on gall location, but not total offspring numbers. No spatial variation in the distribution of male and female adult offspring was detected. Overall, over 25% of the galled ovaries failed to support offspring development, and failure rates were independent of foundress number. More peripheral galls were more likely to fail in figs entered by two foundresses. Gall location in gynodioecious figs is determined largely by the extent to which their basal pedicels expand after galling. Competition for nutrients between galls, with those developing shorter pedicels being at a disadvantage, may explain the results. If pedicel length is related to timing of oviposition, then pollinator eggs laid later are less likely to survive.

  5. 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

  6. 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.

  7. The Goldenrod Ball Gall

    ERIC Educational Resources Information Center

    Fischer, Richard B.

    1974-01-01

    The paper presents a generalized life history of the goldenrod ball gall, a ball-shaped swelling found almost exclusively on the Canada goldenrod, Solidago canadensis, and caused by a peacock fly know as Eurosta soldiaginis. (KM)

  8. Contribution of gall microscopic structure to taxonomy of gallicolous aphids on Pistacia.

    PubMed

    Álvarez, R; Martinez, J-J I; Muñoz-Viveros, A L; Molist, P; Abad-González, J; Nieto Nafría, J M

    2016-09-01

    Aphids inducing galls on Pistacia plants belong to the tribe Fordini. According to the Heie & Wegierek classification, the genera are grouped into three subtribes. Previous microscopic studies showed that this taxonomy is not consistent with the histological characteristics of the galls. In this paper, galls induced by Aplonerura lentisci, Asiphonella cynodonti, Forda riccobonii, Slavun wertheimae and Smynthurodes betae were analyzed for the first time, as well as nine other galls previously described. Based on histological features three groups of galls can be establish: the first group comprises closed galls, induced by Baizongia pistaciae, Geoica utricularia, Rectinasus buxtoni and Slavun wertheimae; the second group includes two species of Geopemphigus (G. blackmani and G. torsus), and the third one is divided into two subgroups, the first comprises Aplonerura lentisci, Asiphonella cynodonti and Geopemphigus morral, and the second that includes Forda formicaria, F. marginata, F. riccobonii, Paracletus cimiciformis and Smynthurodes betae. An identification key of species based on microscopic features of galls is presented. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

  9. Promising Resistance to Fusiform Rust from Southeastern Slash Pines

    Treesearch

    Charles H. Walkinshaw

    1999-01-01

    Two hundred twenty-four disease-free slash pines with good growth and form were tested for rust resistance. Trees in Alabama, Florida, Louisiana, and Mississippi were selected. After artificial inoculations, a low percentage of open-pollinated progeny of 32 selected trees had galls. In progeny from six of those, the number of gall-resistant trees increased from 50 to...

  10. 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

  11. Cytological and histochemical gradients on two Copaifera langsdorffii Desf. (Fabaceae)--Cecidomyiidae gall systems.

    PubMed

    de Oliveira, Denis Coelho; Carneiro, Renê Gonçalves da Silva; Magalhães, Thiago Alves; Isaias, Rosy Mary dos Santos

    2011-10-01

    Previous ultrastructural and histochemical analysis proposed patterns in the accumulation of substances in galls of Diptera: Cecidomyiidae in some plant species of the temperate region. Similar analyses were done to verify the conservativeness of these patterns in the Neotropical region, where a great number of species of Cecidomyiidae is responsible for a wide diversity of morphotypes. Two gall morphotypes induced by Cecidomyiidae in a unique host plant, Copaifera langsdorffii, were studied. The gradients of carbohydrates and the activity of invertases and acid phosphatases were similar, but the cytological gradients and distribution of proteins evidenced that the sites of the induction as well as the amount of neoformed tissues may be peculiar to each gall system. The production of lipids just in the secretory cavities either in the non-galled or galled tissues indicated a potentiality of the host plant which could not be manipulated by the galling insects. Further, the absence of nucleus in the nutritive tissue, an exclusive feature of the horn-shaped galls, indicates cell death attributed to the feeding habit of the galling herbivore.

  12. 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.

  13. 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.

  14. Friction and wear of selected metals and alloys in sliding contact with AISI 440 C stainless steel in liquid methane and in liquid natural gas

    NASA Technical Reports Server (NTRS)

    Wisander, D. W.

    1978-01-01

    Aluminum, titanium, beryllium, nickel, iron, copper, and several copper alloys were run in sliding contact with AISI 440C in liquid methane and natural gas. All of the metals run except copper and the copper alloys of tin and tin-lead showed severely galled wear scars. Friction coefficients varied from 0.2 to 1.0, the lowest being for copper, copper-17 wt. % tin, and copper-8 wt. % tin-22 wt. % lead. The wear rate for copper was two orders of magnitude lower than that of the other metals run. An additional order of magnitude of wear reduction was achieved by the addition of tin and/or lead to copper.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. Wear Behavior of Low-Cost, Lightweight TiC/Ti-6Al-4V Composite Under Fretting: Effectiveness of Solid-Film Lubricant Counterparts

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Street, Kenneth W., Jr.; Sanders, Jeffrey H.; Hager, Carl H., Jr.; Zabinski, Jeffrey S.; VanderWal, Randall L.; Andrews, Rodney; Lerch, Bradley A.

    2007-01-01

    The wear behavior of low-cost, lightweight 10-wt% TiC-particulate-reinforced Ti-6Al-4V matrix composite (TiC/Ti- 6Al-4V) was examined under fretting at 296, 423, and 523 K in air. Bare 10-wt% TiC/Ti-6Al-4V hemispherical pins were used in contact with dispersed multiwalled carbon nanotubes (MWNTs), magnetron-sputtered diamondlike carbon/chromium (DLC/Cr), magnetron-sputtered graphite-like carbon/chromium (GLC/Cr), and magnetron-sputtered molybdenum disulphide/titanium (MoS2/Ti) deposited on Ti-6Al-4V, Ti-48Al-2Cr-2Nb, and nickel-based superalloy 718. When TiC/Ti-6Al-4V was brought into contact with bare Ti-6Al-4V, bare Ti-48Al-2Cr-2Nb, and bare nickel-based superalloy 718, strong adhesion, severe galling, and severe wear occurred. However, when TiC/Ti-6Al-4V was brought into contact with MWNT, DLC/Cr, GLC/Cr, and MoS2/Ti coatings, no galling occurred in the contact, and relatively minor wear was observed regardless of the coating. All the solid-film lubricants were effective from 296 to 523 K, but the effectiveness of the MWNT, DLC/Cr, GLC/Cr, and MoS2/Ti coatings decreased as temperature increased.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. Imaging mass spectrometry of endogenous polypeptides and secondary metabolites from galls induced by root-knot nematodes in tomato roots.

    PubMed

    Barbosa, Eder Alves; Bonfim Junior, Mauro Ferreira; Bloch, Carlos; Rocha, Thales Lima; Engler, Gilbert; de Almeida Engler, Janice

    2018-04-17

    Nematodes are devastating pests that infect most cultivated plant species and cause considerable agricultural losses worldwide. The understanding of metabolic adjustments induced during plant-nematode interaction is crucial to generate resistant plants or to select more efficient molecules to fight against this pest. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) has been used herein for in situ detection and mapping endogenous polypeptides and secondary metabolites from nematode-induced gall tissue. One of the major critical features of this technique is sample preparation, mainly the generation of intact sections of plant cells with their rigid cell walls and vacuolated cytoplasm. Our experimental settings allowed us to obtain sections without contamination of exogenous ions or diffusion of molecules and to map the differential presence of low and high molecular weight ions in uninfected roots compared to nematode-induced galls. We predict the presence of lipids in both uninfected roots and galls, which was validated by MALDI-TOF-MS/MS and high-resolution mass spectrometry analysis of lipid extracts. Based on the isotopic ion distribution profile, both esters and glycerophospholipids were predicted compounds and may be playing an important role in gall development. Our results indicate that the MALDI-MSI technology is a promising tool to identify secondary metabolites as well as peptides and proteins in complex plant tissues like galls to decipher molecular processes responsible for infection and maintenance of these feeding sites during nematode parasitism.

  6. 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.

  7. 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.

  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. Differences in Monoterpene Biosynthesis and Accumulation in Pistacia palaestina Leaves and Aphid-Induced Galls.

    PubMed

    Rand, Karin; Bar, Einat; Ari, Matan Ben; Davidovich-Rikanati, Rachel; Dudareva, Natalia; Inbar, Moshe; Lewinsohn, Efraim

    2017-02-01

    Certain insect species can induce gall formation on numerous plants species. Although the mechanism of gall development is largely unknown, it is clear that insects manipulate their hosts' anatomy, physiology, and chemistry for their own benefit. It is well known that insect-induced galls often contain vast amounts of plant defensive compounds as compared to non-colonized tissues, but it is not clear if defensive compounds can be produced in situ in the galled tissues. To answer this question, we analyzed terpene accumulation patterns and possible independent biosynthetic potential of galls induced by the aphid Baizongia pistaciae L. on the terminal buds of Pistacia palaestina Boiss. We compared monoterpene levels and monoterpene synthase enzyme activity in galls and healthy leaves from individual trees growing in a natural setting. At all developmental stages, monoterpene content and monoterpene synthase activity were consistently (up to 10 fold on a fresh weight basis) higher in galls than in intact non-colonized leaves. A remarkable tree to tree variation in the products produced in vitro from the substrate geranyl diphosphate by soluble protein extracts derived from individual trees was observed. Furthermore, galls and leaves from the same trees displayed enhanced and often distinct biosynthetic capabilities. Our results clearly indicate that galls possess independent metabolic capacities to produce and accumulate monoterpenes as compared to leaves. Our study indicates that galling aphids manipulate the enzymatic machinery of their host plant, intensifying their own defenses against natural enemies.

  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. 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.

  12. Subtropical Interactions: Comparing Galling Insect and Host Plant Diversity in Southern Brazil and Florida.

    PubMed

    D S Mendonça, M; Stiling, P

    2017-11-22

    Gall-inducing insects seem to have a diversity pattern distinct from the usual latitudinal decrease in species, with more species occurring in xeric environments instead. Many questions regarding galler diversity over geographical scales remain unanswered: for example, little is known about beta diversity, and the role super host plants play in local/regional richness. Our aim was to compare galling insect and host plant diversity in different biogeographical regions, but under similar environmental conditions. We sampled short stature coastal woodlands on sandy soils of the Atlantic coast in both USA (Florida) and Brazil (Rio Grande do Sul, RS), between 25° and 30° latitude. Little-used 200-m long trails were searched during 90 min for galls; there were four trails in USA and five in Brazil. Gall functional traits (galled plant organ, gall shape and colour) proportions were not different between Florida and RS. Local galling and host plant species richness also did not differ, and neither did regional galling diversity. The beta diversity pattern, however, was distinct: sites in Florida have more similar galling faunas than sites in RS. Common diversity patterns indicate common environmental biotic (plant diversity, vegetation structure) and abiotic (climate, soil) factors might be contributing to these similar responses. As Brazilian sites are in the Atlantic forest hotspot, a high galling insect beta diversity might be caused by a higher heterogeneity at larger scales-sample-based rarefaction curves were ascending for Brazil, but not for USA. Myrtaceans were super hosts in Brazil, but not in Florida, where oaks take up this role.

  13. Carcinoma transverse colon masquerading as carcinoma gall bladder

    PubMed Central

    Kumar, Ashwani; Singh, Harnam; Singh, Gurpreet; Singh, Bimaljot; Chauhan, Mahak

    2014-01-01

    Colorectal cancer is one of the most common cancer worldwide .Its incidence is reported to be increasing in developing countries. It commonly presents with weight loss, anaemia, lump abdomen, change of bowel habit, obstruction or fresh rectal bleeding. Beside these common modes of presentations, there are some rare manifestations which masqueraded as different disease like obstructive jaundice, empyema gall bladder or cholecystitis. A 60-year-old male presented to hospital with right sided pain abdomen. On abdominal examination mild tenderness was present in right hypochondrium. Intra operatively gall bladder was separated from the adjoining gut, peritoneum and liver bed and was removed. On further exploration, there was a large mass in the vicinity of the gall bladder related to transverse colon. Extended right hemicolectomy was done. Histopathological examination of gut mass revealed adenocarcinoma of transverse colon with free margins and gall bladder showed cholecystitis with no evidence of malignancy. We present an interesting case of colon cancer colon that caused diagnostic confusion by mimicking as cholecystitis. Colorectal cancer constitutes a major public health issue globally. Therefore, public awareness, screening of high-risk populations, early diagnosis and effective treatment and follow-up will help to reduce its occurance and further complications. PMID:24772345

  14. Carcinoma transverse colon masquerading as carcinoma gall bladder.

    PubMed

    Munghate, Anand; Kumar, Ashwani; Singh, Harnam; Singh, Gurpreet; Singh, Bimaljot; Chauhan, Mahak

    2014-04-01

    Colorectal cancer is one of the most common cancer worldwide .Its incidence is reported to be increasing in developing countries. It commonly presents with weight loss, anaemia, lump abdomen, change of bowel habit, obstruction or fresh rectal bleeding. Beside these common modes of presentations, there are some rare manifestations which masqueraded as different disease like obstructive jaundice, empyema gall bladder or cholecystitis. A 60-year-old male presented to hospital with right sided pain abdomen. On abdominal examination mild tenderness was present in right hypochondrium. Intra operatively gall bladder was separated from the adjoining gut, peritoneum and liver bed and was removed. On further exploration, there was a large mass in the vicinity of the gall bladder related to transverse colon. Extended right hemicolectomy was done. Histopathological examination of gut mass revealed adenocarcinoma of transverse colon with free margins and gall bladder showed cholecystitis with no evidence of malignancy. We present an interesting case of colon cancer colon that caused diagnostic confusion by mimicking as cholecystitis. Colorectal cancer constitutes a major public health issue globally. Therefore, public awareness, screening of high-risk populations, early diagnosis and effective treatment and follow-up will help to reduce its occurance and further complications.

  15. Galle Crater Floor

    NASA Image and Video Library

    2015-02-05

    The unusual texture seen in this image of Galle Crater is likely layered deposits that have been eroded. Small dune and windstreak features in this image from NASA 2001 Mars Odyssey spacecraft, indicate that winds are part of the erosive process. Orbit Number: 57733 Latitude: -51.7743 Longitude: 329.135 Instrument: VIS Captured: 2014-12-19 11:13 http://photojournal.jpl.nasa.gov/catalog/PIA19191

  16. 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

  17. 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.

  18. 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.

  19. Bud gall midges - potential invaders on larches in North America

    Treesearch

    Yuri N. Baranchikov

    2007-01-01

    Larch bud gall midges (Diptera: Cecidomyiidae) form a specialized group of gall insects inhabiting buds of larch (Larix) in the northern Palaearctic Region. Currently there are four described species in this group. Dasineura kellneri Henschel is found in Central Europe and infests Larix decidua; D....

  20. 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.

  1. DNA Methylation Mediated Control of Gene Expression Is Critical for Development of Crown Gall Tumors

    PubMed Central

    Kneitz, Susanne; Weber, Dana; Fuchs, Joerg; Hedrich, Rainer; Deeken, Rosalia

    2013-01-01

    Crown gall tumors develop after integration of the T-DNA of virulent Agrobacterium tumefaciens strains into the plant genome. Expression of the T-DNA–encoded oncogenes triggers proliferation and differentiation of transformed plant cells. Crown gall development is known to be accompanied by global changes in transcription, metabolite levels, and physiological processes. High levels of abscisic acid (ABA) in crown galls regulate expression of drought stress responsive genes and mediate drought stress acclimation, which is essential for wild-type-like tumor growth. An impact of epigenetic processes such as DNA methylation on crown gall development has been suggested; however, it has not yet been investigated comprehensively. In this study, the methylation pattern of Arabidopsis thaliana crown galls was analyzed on a genome-wide scale as well as at the single gene level. Bisulfite sequencing analysis revealed that the oncogenes Ipt, IaaH, and IaaM were unmethylated in crown galls. Nevertheless, the oncogenes were susceptible to siRNA–mediated methylation, which inhibited their expression and subsequently crown gall growth. Genome arrays, hybridized with methylated DNA obtained by immunoprecipitation, revealed a globally hypermethylated crown gall genome, while promoters were rather hypomethylated. Mutants with reduced non-CG methylation developed larger tumors than the wild-type controls, indicating that hypermethylation inhibits plant tumor growth. The differential methylation pattern of crown galls and the stem tissue from which they originate correlated with transcriptional changes. Genes known to be transcriptionally inhibited by ABA and methylated in crown galls became promoter methylated upon treatment of A. thaliana with ABA. This suggests that the high ABA levels in crown galls may mediate DNA methylation and regulate expression of genes involved in drought stress protection. In summary, our studies provide evidence that epigenetic processes regulate gene

  2. DNA methylation mediated control of gene expression is critical for development of crown gall tumors.

    PubMed

    Gohlke, Jochen; Scholz, Claus-Juergen; Kneitz, Susanne; Weber, Dana; Fuchs, Joerg; Hedrich, Rainer; Deeken, Rosalia

    2013-01-01

    Crown gall tumors develop after integration of the T-DNA of virulent Agrobacterium tumefaciens strains into the plant genome. Expression of the T-DNA-encoded oncogenes triggers proliferation and differentiation of transformed plant cells. Crown gall development is known to be accompanied by global changes in transcription, metabolite levels, and physiological processes. High levels of abscisic acid (ABA) in crown galls regulate expression of drought stress responsive genes and mediate drought stress acclimation, which is essential for wild-type-like tumor growth. An impact of epigenetic processes such as DNA methylation on crown gall development has been suggested; however, it has not yet been investigated comprehensively. In this study, the methylation pattern of Arabidopsis thaliana crown galls was analyzed on a genome-wide scale as well as at the single gene level. Bisulfite sequencing analysis revealed that the oncogenes Ipt, IaaH, and IaaM were unmethylated in crown galls. Nevertheless, the oncogenes were susceptible to siRNA-mediated methylation, which inhibited their expression and subsequently crown gall growth. Genome arrays, hybridized with methylated DNA obtained by immunoprecipitation, revealed a globally hypermethylated crown gall genome, while promoters were rather hypomethylated. Mutants with reduced non-CG methylation developed larger tumors than the wild-type controls, indicating that hypermethylation inhibits plant tumor growth. The differential methylation pattern of crown galls and the stem tissue from which they originate correlated with transcriptional changes. Genes known to be transcriptionally inhibited by ABA and methylated in crown galls became promoter methylated upon treatment of A. thaliana with ABA. This suggests that the high ABA levels in crown galls may mediate DNA methylation and regulate expression of genes involved in drought stress protection. In summary, our studies provide evidence that epigenetic processes regulate gene

  3. 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

  4. Host manipulation by the orange leafhopper Cicadulina bipunctata: gall induction on distant leaves by dose-dependent stimulation

    NASA Astrophysics Data System (ADS)

    Matsukura, Keiichiro; Matsumura, Masaya; Tokuda, Makoto

    2009-09-01

    The evolution of the gall-inducing ability in insects and the adaptive significance of the galling habit have been addressed by many studies. Cicadulina bipunctata, the maize orange leafhopper, is an ideal study organism for evaluating these topics because it can be mass-reared and it feeds on model plants such as rice ( Oryza sativa) and maize ( Zea mays). To reveal differences between gall inductions by C. bipunctata and other gall inducers, we conducted four experiments concerning (a) the relationship between the feeding site and gall-induction sites of C. bipunctata on maize, (b) the effects of leafhopper sex and density, (c) the effects of length of infestation on gall induction, and (d) the effects of continuous infestation. C. bipunctata did not induce galls on the leaves where it fed but induced galls on other leaves situated at more distal positions. The degree of gall induction was significantly correlated with infestation density and length. These results indicate that C. bipunctata induces galls in a dose-dependent manner on leaves distant from feeding sites, probably by injecting chemical(s) to the plant during feeding. We suggest that insect galls are induced by a chemical stimulus injected by gall inducers during feeding into the hosts.

  5. Acute gall bladder perforation--a dilemma in early diagnosis.

    PubMed Central

    Ong, C L; Wong, T H; Rauff, A

    1991-01-01

    Gall bladder perforation is a rare complication of cholecystitis. A definitive diagnosis is uncommon before surgery and the morbidity and mortality associated with this condition are high. We report six patients with gall bladder perforation to show the difficulty of making an early diagnosis. The history and the clinical findings of these patients are reviewed to highlight diagnostic pitfalls. PMID:1885081

  6. 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.

  7. Crown gall transformation of tobacco callus cells by cocultivation with Agrobacterium tumefaciens

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

    Muller, A.; Manzara, T.; Lurquin, P.F.

    1984-09-17

    Incubation of cells from squashed tobacco callus tissue with virulent Agrobacterium tumefaciens leads to the production of cells displaying a crown gall phenotype. In vitro crown gall transformation of dicotyledonous plant cells has been demonstrated after cocultivation of cell-wall regenerating mesophyll protoplasts with Agrobacterium tumefaciens cells. In addition, it has been shown that protoplasts freshly isolated from suspension cultures, when treated with A. tumefaciens spheroplasts and a fusogen, also generated cells displaying a typical crown gall phenotype, i.e., phytohormone-independent growth and opine synthesis. Subsequently, both techniques were used to transfer and express foreign genes in plant cells via A. tumefaciensmore » T-DNA integration. For practical purposes, it would be advantageous to be able to perform crown gall transformation of plant cells in tissue culture. The authors report here for the first time the production of Nicotiana tabacum crown gall cells after cocultivation of callus tissue with A. tumefaciens A136 cells. 11 references, 1 figure, 1 table.« less

  8. Winter Biology and Freeze Tolerance in the Goldenrod Gall Fly

    ERIC Educational Resources Information Center

    Sandro, Luke H.; Lee, Richard E., Jr.

    2006-01-01

    This article describes a variety of opportunities for educational activities that can be found in the complex, yet easy-to-manipulate, trophic relationships between goldenrod plants, insects that induce gall formation, and the natural enemies of these gallmakers. Gall collection, measurement, and observation (exit holes, larval response,…

  9. 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.

  10. 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.

  11. Antioxidant activity of Syzygium cumini leaf gall extracts

    PubMed Central

    Eshwarappa, Ravi Shankara Birur; Iyer, Raman Shanthi; Subbaramaiah, Sundara Rajan; Richard, S Austin; Dhananjaya, Bhadrapura Lakkappa

    2014-01-01

    Introduction: Free radicals are implicated in several metabolic diseases and the medicinal properties of plants have been explored for their potent antioxidant activities to counteract metabolic disorders. This research highlights the chemical composition and antioxidant potential of leaf gall extracts (aqueous and methanol) of Syzygium cumini (S. cumini), which have been extensively used in traditional medications to treat various metabolic diseases. Methods: The antioxidant activities of leaf gall extracts were examined using diphenylpicrylhydrazyl (DPPH), nitric oxide scavenging, hydroxyl scavenging and ferric reducing power (FRAP) methods. Results: In all the methods, the methanolic extract showed higher antioxidant potential than the standard ascorbic acid. The presence of phenolics, flavonoids, phytosterols, terpenoids, and reducing sugars was identified in both the extracts. When compared, the methanol extract had the highest total phenolic and flavonoid contents at 474±2.2 mg of GAE/g d.w and 668±1.4 mg of QUE/g d.w, respectively. The significant high antioxidant activity can be positively correlated to the high content of total polyphenols/flavonoids of the methanol extract. Conclusion: The present study confirms the folklore use of S. cumini leaves gall extracts as a natural antioxidant and justifies its ethnobotanical use. Further, the result of antioxidant properties encourages the use of S. cumini leaf gall extracts for medicinal health, functional food and nutraceuticals applications. PMID:25035854

  12. Mapping fusiform rust resistance genes within a complex mating design of loblolly pine

    Treesearch

    Tania Quesada; Marcio F.R. Resende Jr.; Patricio Munoz; Jill L. Wegrzyn; David B. Neale; Matias Kirst; Gary F. Peter; Salvador A. Gezan; C.Dana Nelson; John M. Davis

    2014-01-01

    Fusiform rust resistance can involve gene-for-gene interactions where resistance (Fr) genes in the host interact with corresponding avirulence genes in the pathogen, Cronartium quercuum f.sp. fusiforme (Cqf). Here, we identify trees with Fr genes in a loblolly pine population derived from a complex mating design challenged with two Cqf inocula (one gall and 10 gall...

  13. Galle Cr. Dunes

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03637 Galle Cr. Dunes

    These dunes are located on the floor of Galle Crater.

    Image information: VIS instrument. Latitude 51.5S, Longitude 329.0E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  14. Extreme resistance to desiccation and microclimate-related differences in cold-hardiness of gall wasps (Hymenoptera: Cynipidae) overwintering on roses in southern Canada.

    PubMed

    Williams, Jason B; Shorthouse, Joseph D; Lee, Richard E

    2002-07-01

    Four species of cynipid wasp of the genus Diplolepis that induce galls on roses (Rosa species) in southern Canada and two species of inquiline cynipid associated with these galls were studied for their cold-hardiness and resistance to water loss and for possible links between these adaptations. Mid-winter-acclimated supranivean D. spinosa and Periclistus pirata had lower supercooling points (-38 to -40 degrees C) and higher hemolymph osmolalities (1760-1849 mosmol kg(-1)) than subnivean D. polita, D. gracilis, D. radicum and Periclistus sp. (-31 to -32 degrees C and 977-1464 mosmol kg(-1), respectively). During a simulated transition from summer/fall to mid-winter conditions, the glycerol concentration of D. spinosa more than tripled, reaching a final value of 0.98 moll(-1), while its supercooling point decreased by 13 degrees C from the initial value of -27.4 degrees C; however, glycerol concentration and supercooling point did not change for the subnivean species. The permeability of the cuticle of all species was extremely low (0.33-1.00 microg h(-1) cm(-2) mmHg(-1) at 5 degrees C and 0 % relative humidity; 1 mmHg=0.133 kPa), even compared with that of desert species; however, there was no difference in cuticular permeability between supranivean and subnivean prepupae. Transition temperatures ranged between 32.3 and 34.6 degrees C; below 30 degrees C, temperature had little effect on rates of water loss for all species (Q(10)=1.13-1.87).

  15. Could the Extended Phenotype Extend to the Cellular and Subcellular Levels in Insect-Induced Galls?

    PubMed Central

    Carneiro, Renê Gonçalves da Silva; Pacheco, Priscilla; Isaias, Rosy Mary dos Santos

    2015-01-01

    Neo-ontogenesis of plant galls involves redifferentiation of host plant tissues to express new phenotypes, when new cell properties are established via structural-functional remodeling. Herein, Psidium cattleianum leaves and Nothotrioza cattleiani galls are analyzed by developmental anatomy, cytometry and immunocytochemistry of cell walls. We address hypothesis-driven questions concerning the organogenesis of globoid galls in the association of P. cattleianum - N. cattleianum, and P. myrtoides - N. myrtoidis. These double co-generic systems represent good models for comparing final gall shapes and cell lineages functionalities under the perspective of convergent plant-dependent or divergent insect-induced characteristics. Gall induction, and growth and development are similar in both galls, but homologous cell lineages exhibit divergent degrees of cell hypertrophy and directions of elongation. Median cortical cells in P. cattleianum galls hypertrophy the most, while in P. myrtoides galls there is a centrifugal gradient of cell hypertrophy. Cortical cells in P. cattleianum galls tend to anisotropy, while P. myrtoidis galls have isotropically hypertrophied cells. Immunocytochemistry evidences the chemical identity and functional traits of cell lineages: epidermal cells walls have homogalacturonans (HGAs) and galactans, which confer rigidity to sites of enhanced cell division; oil gland cell walls have arabinogalactan proteins (AGPs) that help avoiding cell death; and parenchyma cell walls have HGAs, galactans and arabinans, which confer porosity. Variations in such chemical identities are related to specific sites of hypertrophy. Even though the double co-generic models have the same macroscopic phenotype, the globoid morphotype, current analyses indicate that the extended phenotype of N. cattleiani is substantiated by cellular and subcellular specificities. PMID:26053863

  16. Galling Insects of the Brazilian Páramos: Species Richness and Composition Along High-Altitude Grasslands.

    PubMed

    Coelho, Marcel S; Carneiro, Marco Antônio Alves; Branco, Cristina A; Borges, Rafael Augusto Xavier; Fernandes, G Wilson

    2017-12-08

    In this work, we investigated the factors that determine the distribution of galling insects in high-altitude grasslands, locally called 'campos de altitude' of Mantiqueira Range and tested whether 1) richness of galling insects decreases with altitude, 2) galling insect richness increases with plant richness, 3) variation in galling insect diversity is predominantly a consequence of its β component, and 4) turnover is the main mechanism driving the beta diversity of both galling insects and plants. Galling insect richness did not exhibit a negative relationship with altitude, but it did increase with plant richness. The additive partition of regional richness (γ) into its local and beta components showed that local diversity (α) of galling insects and plants was relatively low in relation to regional diversity; the β component incorporated most of the regional diversity. This pattern was also found in the multiscale analysis of the additive partition for galling insects and plants. The beta diversity of galling insects and plants was driven predominantly by the process of turnover and minimally by nesting. The results reported here point out that the spatial distribution of galling insects is best explained by historical factors, such as the distribution of genera and species of key host plants, as well as their relation to habitat, than ecological effects such as hygrothermal stress - here represented by altitude. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. Gradients of metabolite accumulation and redifferentiation of nutritive cells associated with vascular tissues in galls induced by sucking insects

    PubMed Central

    Carneiro, Renê Gonçalves da Silva; Isaias, Rosy Mary dos Santos

    2015-01-01

    Plant cells respond to abiotic and biotic stimuli, which generate adaptive phenotypes in plant organs. In the case of plant galls, cell phenotypes are adaptive for the gall inducer and assume characteristics mainly linked to its protection and nutrition. Herein, the cytological development and histochemical profile of Nothotrioza cattleiani galls, a sucking insect, on the leaves of Psidium cattleianum are compared with those of other galls, especially N. myrtoidis galls, searching for conserved and divergent alterations in cell fates and cycles. Leaf cell fates are completely changed within galls, except for epidermal cells, but the comparison between Nothotrioza spp. galls shows conserved fates. Nevertheless, cytological development of N. cattleiani galls is different from the standby-redifferentiation of N. myrtoidis galls. Starch and lignins, and reducing sugars form centrifugal and centripetal gradients of accumulation, respectively. Proteins, total phenolics, terpenoids, proanthocyanidins and reactive oxygen species are detected in bidirectional gradients, i.e. weak or undetectable reaction in the median cortical cells that is gradually more intense in the cell layers towards the inner and outer surfaces of the gall. True nutritive cells associated with vascular tissues, together with the bidirectional gradients of metabolite accumulation, are herein reported for the first time in insect galls. The globoid galls of N. cattleiani, though macro-morphologically similar to the galls of N. myrtoidis, are distinct and unique among insect galls, as far as the cellular, subcellular and histochemical traits are concerned. Thus, the traits of the galls on P. cattleianum studied herein represent the extended phenotypes of their inducers. PMID:26209687

  10. 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

  11. 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.

  12. Spatial distribution of galls caused by Aculus tetanothrix (Acari: Eriophyoidea) on arctic willows.

    PubMed

    Kuczyński, Lechosław; Skoracka, Anna

    2005-01-01

    The distribution of galls caused by Aculus tetanothrix (Acari: Eriophyoidea) on three Salix species was studied. The factors influencing this distribution were analysed, i.e. willow species, study area and shoot length. Spatial pattern of gall distribution within the shoot was also examined. The study was conducted in Russia, Kola Peninsula. Densities of galls caused by A. tetanothrix differed significantly among willow species. Considerably higher gall density was recorded in the White Sea coast than in the Khibiny Mountains. This may be explained by the influence of a milder maritime climate that favors mite occurrence compared to a harsh and variable mountain climate that limits mite abundance. There was no relationship between the gall density and the shoot length. The highest density of galls was recorded on the inner offshoots; within the offshoot, there was a maximum density on the fifth leaf. This pattern was repeatable for all shoots studied, independent of the study area, willow species and length of shoots, suggesting the optimal conditions for A. tetanothrix exist on leaves in the middle part of a shoot. This distribution pattern may be an effect of the trade-off between the costs and benefits resulting from leaf quality and mite movement along the shoot. This hypothesis, however, needs to be tested experimentally.

  13. Reacquisition of New Meristematic Sites Determines the Development of a New Organ, the Cecidomyiidae Gall on Copaifera langsdorffii Desf. (Fabaceae).

    PubMed

    Carneiro, Renê G S; Isaias, Rosy M S; Moreira, Ana S F P; Oliveira, Denis C

    2017-01-01

    The development of gall shapes has been attributed to the feeding behavior of the galling insects and how the host tissues react to galling stimuli, which ultimately culminate in a variable set of structural responses. A superhost of galling herbivores, Copaifera langsdorffii , hosts a bizarre "horn-shaped" leaflet gall morphotype induced by an unidentified species of Diptera: Cecidomyiidae. By studying the development of this gall morphotype under the anatomical and physiological perspectives, we demonstrate the symptoms of the Cecidomyiidae manipulation over plant tissues, toward the cell redifferentiation and tissue neoformation. The most prominent feature of this gall is the shifting in shape from growth and development phase toward maturation, which imply in metabolites accumulation detected by histochemical tests in meristem-like group of cells within gall structure. We hypothesize that the development of complex galls, such as the horn-shaped demands the reacquisition of cell meristematic competence. Also, as mature galls are green, their photosynthetic activity should be sufficient for their oxygenation, thus compensating the low gas diffusion through the compacted gall parenchyma. We currently conclude that the galling Cecidomyiidae triggers the establishment of new sites of meristematic tissues, which are ultimately responsible for shifting from the young conical to the mature horn-shaped gall morphotype. Accordingly, the conservative photosynthesis activity in gall site maintains tissue homeostasis by avoiding hypoxia and hipercarbia in the highly compacted gall tissues.

  14. Feltiella acarisuga (predatory gall midge)

    USDA-ARS?s Scientific Manuscript database

    The predatory gall midge, Feltiella acarisuga is one of the most effective and widespread natural enemies of spider mites. Because of their flying and prey detecting capabilities, and high feeding potential, it is considered an important natural enemy of the two-spotted spider mite in a number of cr...

  15. 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.

  16. [Correlation of infection with the physical and chemical characteristics of gall bladder contents].

    PubMed

    Sulaberidze, G T; Rachvelishvili, B Kh; Gelbakhiani, G P; Barbakadze, G G; Kapanadze, A G

    2005-06-01

    The aim of the study was to investigate pH and viscosity (h) of gall bladder contents during cholelithiasis and establishment of their correlation with bacterial and HBV infections. Seventy-eight patients undergone the planned cholecystectomy were investigated. 5 healthy persons (control group) were also involved into the study. In all cases the markers of HBV (Anti-HB core IgG, Anti-HB core IgM, HBsAg) in blood were detected, also bacteriological analysis of gall bladder tissue was performed. In 78 cases (I group) pH of gall bladder contents was measured, in 29 cases (II group), also viscosity of gall was studied. In the control group pH and viscosity were detected. Statistical analysis was performed using ANOVA method. Bacteriological study revealed presence of bacterial infection in gall bladder tissue in 34 cases (43,6%), in 30 patients Anti-HB core antibodies were found in the blood, in 13 cases (16,7%) coincidence of bacterial and HBV infection was documented. Mean indexes of pH and viscosity appeared to be significantly higher in the operated group (pH--7,30, h 2,1 mm(2)/sec), then in the control group (pH--6,74, h--1,34 mm(2)/sec); this indexes were highest in the infected patients. Thus, according to results of the study, changes of pH and viscosity of gall bladder contents could be considered as the useful indexes of initial stage of cholelithiasis and their values depend on the presence of bacterial or HBV infection of gall bladder.

  17. 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.

  18. Galling by Rhopalomyia solidaginis alters Solidago altissima architecture and litter nutrient dynamics in an old-field ecosystem

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

    Crutsinger, Greg; Habenicht, Melissa N; Classen, Aimee T

    2008-01-01

    Plant-insect interactions can alter ecosystem processes, especially if the insects modify plant architecture, quality, or the quantity of leaf litter inputs. In this study, we investigated the interactions between the gall midge Rhopalomyia solidaginis and tall goldenrod, Solidago altissima, to quantify the degree to which the midge alters plant architecture and how the galls affect rates of litter decomposition and nutrient release in an old-field ecosystem. R. solidaginis commonly leads to the formation of a distinct apical rosette gall on S. altissima and approximately 15% of the ramets in a S. altissima patch were galled (range: 3-34%). Aboveground biomass ofmore » galled ramets was 60% higher and the leaf area density was four times greater on galled leaf tissue relative to the portions of the plant that were not affected by the gall. Overall decomposition rate constants did not differ between galled and ungalled leaf litter. However, leaf-litter mass loss was lower in galled litter relative to ungalled litter, which was likely driven by modest differences in initial litter chemistry; this effect diminished after 12 weeks of decomposition in the field. The proportion of N remaining was always higher in galled litter than in ungalled litter at each collection date indicating differential release of nitrogen in galled leaf litter. Several studies have shown that plant-insect interactions on woody species can alter ecosystem processes by affecting the quality or quantity of litter inputs. Our results illustrate how plant-insect interactions in an herbaceous species can affect ecosystem processes by altering the quality and quantity of litter inputs. Given that S. altissima dominates fields and roadsides and that R. solidaginis galls are highly abundant throughout eastern North America, these interactions are likely to be important for both the structure and function of old-field ecosystems.« less

  19. 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

  20. Metatranscriptome Analysis of Fig Flowers Provides Insights into Potential Mechanisms for Mutualism Stability and Gall Induction.

    PubMed

    Martinson, Ellen O; Hackett, Jeremiah D; Machado, Carlos A; Arnold, A Elizabeth

    2015-01-01

    A striking property of the mutualism between figs and their pollinating wasps is that wasps consistently oviposit in the inner flowers of the fig syconium, which develop into galls that house developing larvae. Wasps typically do not use the outer ring of flowers, which develop into seeds. To better understand differences between gall and seed flowers, we used a metatranscriptomic approach to analyze eukaryotic gene expression within fig flowers at the time of oviposition choice and early gall development. Consistent with the unbeatable seed hypothesis, we found significant differences in gene expression between gall- and seed flowers in receptive syconia prior to oviposition. In particular, transcripts assigned to flavonoids and carbohydrate metabolism were significantly up-regulated in gall flowers relative to seed flowers. In response to oviposition, gall flowers significantly up-regulated the expression of chalcone synthase, which previously has been connected to gall formation in other plants. We propose several genes encoding proteins with signal peptides or associations with venom of other Hymenoptera as candidate genes for gall initiation or growth. This study simultaneously evaluates the gene expression profile of both mutualistic partners in a plant-insect mutualism and provides insight into a possible stability mechanism in the ancient fig-fig wasp association.

  1. Metatranscriptome Analysis of Fig Flowers Provides Insights into Potential Mechanisms for Mutualism Stability and Gall Induction

    PubMed Central

    Martinson, Ellen O.; Hackett, Jeremiah D.; Machado, Carlos A.; Arnold, A. Elizabeth

    2015-01-01

    A striking property of the mutualism between figs and their pollinating wasps is that wasps consistently oviposit in the inner flowers of the fig syconium, which develop into galls that house developing larvae. Wasps typically do not use the outer ring of flowers, which develop into seeds. To better understand differences between gall and seed flowers, we used a metatranscriptomic approach to analyze eukaryotic gene expression within fig flowers at the time of oviposition choice and early gall development. Consistent with the unbeatable seed hypothesis, we found significant differences in gene expression between gall- and seed flowers in receptive syconia prior to oviposition. In particular, transcripts assigned to flavonoids and carbohydrate metabolism were significantly up-regulated in gall flowers relative to seed flowers. In response to oviposition, gall flowers significantly up-regulated the expression of chalcone synthase, which previously has been connected to gall formation in other plants. We propose several genes encoding proteins with signal peptides or associations with venom of other Hymenoptera as candidate genes for gall initiation or growth. This study simultaneously evaluates the gene expression profile of both mutualistic partners in a plant-insect mutualism and provides insight into a possible stability mechanism in the ancient fig-fig wasp association. PMID:26090817

  2. Developmental pathway from leaves to galls induced by a sap-feeding insect on Schinus polygamus (Cav.) Cabrera (Anacardiaceae).

    PubMed

    Dias, Graciela G; Ferreira, Bruno G; Moreira, Gilson R P; Isaias, Rosy M S

    2013-03-01

    Galling sap-feeding insects are presumed to cause only minor changes in host plant tissues, because they usually do not require development of nutritive tissues for their own use. This premise was examined through comparison of the histometry, cytometry and anatomical development of non-galled leaves and galls of Calophya duvauae (Scott) (Hemiptera: Calophyidae) on Schinus polygamus (Cav.) Cabrera (Anacardiaceae). Cell fates changed from non-galled leaves to galls during the course of tissue differentiation. C. duvauae caused changes in dermal, ground, and vascular systems of the leaves of S. polygamus. Its feeding activity induced the homogenization of the parenchyma, and the neoformation of vascular bundles and trichomes. The histometric and cytometric data revealed compensatory effects of hyperplasia and cell hypertrophy in the epidermis, with hyperplasia predominating in the adaxial epidermis. There was a balance between these processes in the other tissues. Thus, we found major differences between the developmental pathways of non-galled leaves and galls. These changes were associated with phenotypic alterations related to shelter and appropriate microenvironmental conditions for the gall inducer. The nondifferentiation of a typical nutritive tissue in this case was compared to other non-phylogenetically related arthropod gall systems, and is suggested to result from convergence associated with the piercing feeding apparatus of the corresponding gall-inducer.

  3. Nematodes from galls on Myrtaceae. IV. Fergusobia from flat leaf galls on Eucalyptus and Corymbia, with descriptions of two new species.

    PubMed

    Davies, Kerrie A; Giblin-Davis, Robin M; Ye, Weimin; Taylor, Gary S; Thomas, W Kelley

    2013-11-26

    Two new species of Fergusobia are described. Both were collected from flat leaf galls from South Australia, one on Eucalyptus microcarpa and the other on E. porosa. Fergusobia microcarpae n. sp. Davies is characterised by the combination of a C-shaped parthenogenetic female with a short, broadly rounded conoid tail, an arcuate to open C-shaped infective female with an hemispherical tail tip, and arcuate to J-shaped males with angular spicules and short peloderan bursa. Fergusobia porosae n. sp. Davies is similar in having an arcuate to C-shaped parthenogenetic female with a small conoid tail, an almost straight to arcuate infective female with an hemispherical tail tip, and males that are almost straight to barely J-shaped with angular spicules and short peloderan bursa. They differ in that the bodies of parthenogenetic and infective females of F. microcarpae n. sp. are more curved than in F. porosae n. sp. Other known similar forms of Fergusobia/Fergusonina galls are outlined and the larval shield morphologies of their associated mutualistic Fergusonina fly species are discussed where known. An inventory of all known Fergusobia/Fergusonina associations from flat leaf galls from Corymbia spp. and Eucalyptus spp. is presented. Relationships of Fergusobia nematodes were inferred from analysis of sequences of 28S rDNA D2/D3 domains and a portion of mitochondrial DNA cytochrome oxidase subunit I (mtCOI). Nematodes from flat leaf galls appeared in two clades. 

  4. Mechanical properties of low-nickel stainless steel

    NASA Technical Reports Server (NTRS)

    Montano, J. W.

    1978-01-01

    Demand for improved corrosion-resistant steels, coupled with increased emphasis on conserving strategic metals, has led to development of family of stainless steels in which manganese and nitrogen are substituted for portion of usual nickel content. Advantages are approximately-doubled yield strength in annealed condition, better resistance to stress-corrosion cracking, retention of low magnetic permeability even after severe cold working, excellent strength and ductility at cryogenic temperatures, superior resistance to wear and galling, and excellent high-temperature properties.

  5. 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

  6. 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.

  7. Using stamping punch force variation for the identification of changes in lubrication and wear mechanism

    NASA Astrophysics Data System (ADS)

    Voss, B. M.; Pereira, M. P.; Rolfe, B. F.; Doolan, M. C.

    2017-09-01

    The growth in use of Advanced High Strength Steels in the automotive industry for light-weighting and safety has increased the rates of tool wear in sheet metal stamping. This is an issue that adds significant costs to production in terms of manual inspection and part refinishing. To reduce these costs, a tool condition monitoring system is required and a firm understanding of process signal variation must form the foundation for any such monitoring system. Punch force is a stamping process signal that is widely collected by industrial presses and has been linked closely to part quality and tool condition, making it an ideal candidate as a tool condition monitoring signal. In this preliminary investigation, the variation of punch force due to different lubrication conditions and progressive wear are examined. Linking specific punch force signature changes to developing lubrication and wear events is valuable for die wear and stamping condition monitoring. A series of semi-industrial channel forming trials were conducted under different lubrication regimes and progressive die wear. Punch force signatures were captured for each part and Principal Component Analysis (PCA) was applied to determine the key Principal Components of the signature data sets. These Principal Components were linked to the evolution of friction conditions over the course of the stroke for the different lubrication regimes and mechanism of galling wear. As a result, variation in punch force signatures were correlated to the current mechanism of wear dominant on the formed part; either abrasion or adhesion, and to changes in lubrication mechanism. The outcomes of this study provide important insights into punch force signature variation, that will provide a foundation for future work into the development of die wear and lubrication monitoring systems for sheet metal stamping.

  8. Assemblage of filamentous fungi associated with aculeate hymenopteran brood in reed galls.

    PubMed

    Heneberg, Petr; Bizos, Jiří; Čmoková, Adéla; Kolařík, Miroslav; Astapenková, Alena; Bogusch, Petr

    2016-01-01

    Monotypic stands of common reed and the reed-gall-associated insect assemblages are distributed worldwide. However, fungi associated with these assemblages have not been characterized in detail. Here we examined 5200 individuals (12 species) of immature aculeate hymenopterans or their parasitoids collected at 34 sampling sites in Central Europe. We noticed fungal outgrowth on exoskeletons of 83 (1.60%) larvae and pupae. The most common host was eudominant Pemphredon fabricii. However, the less abundant aculeate hymenopteran reed gall inquilines were infected at higher prevalence, these included Trypoxylon deceptorium, Trypoxylon minus, Hoplitis leucomelana and Hylaeus moricei (all considered new host records). We identified three fungal species, Penicillium buchwaldii (72% of cases), Aspergillus pseudoglaucus (22%) and Penicillium quebecense (6%). When multibrooded nests were affected, only a part of individuals was infected in 62% of cases. The sampling site-specific infection rate reached up to 13%, thus fungal infections should be considered an important variable driving the abundance of gall inquilines. Infections of generalist host species were more frequent than those of reed gall specialists, suggesting that suboptimal conditions decreased the immunocompetence of non-specialized species, which only occasionally nest in reed galls and feed in reed beds. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Unexpected High Diversity of Galling Insects in the Amazonian Upper Canopy: The Savanna Out There

    PubMed Central

    Julião, Genimar R.; Venticinque, Eduardo M.; Fernandes, G. Wilson; Price, Peter W.

    2014-01-01

    A relatively large number of studies reassert the strong relationship between galling insect diversity and extreme hydric and thermal status in some habitats, and an overall pattern of a greater number of galling species in the understory of scleromorphic vegetation. We compared galling insect diversity in the forest canopy and its relationship with tree richness among upland terra firme, várzea, and igapó floodplains in Amazonia, Brazil. The soils of these forest types have highly different hydric and nutritional status. Overall, we examined the upper layer of 1,091 tree crowns. Galling species richness and abundance were higher in terra firme forests compared to várzea and igapó forests. GLM-ANCOVA models revealed that the number of tree species sampled in each forest type was determinant in the gall-forming insect diversity. The ratio between galling insect richness and number of tree species sampled (GIR/TSS ratio) was higher in the terra firme forest and in seasonally flooded igapó, while the várzea presented the lowest GIR/TSS ratio. In this study, we recorded unprecedented values of galling species diversity and abundance per sampling point. The GIR/TSS ratio from várzea was approximately 2.5 times higher than the highest value of this ratio ever reported in the literature. Based on this fact, we ascertained that várzea and igapó floodplain forests (with lower GIA and GIR), together with the speciose terra firme galling community emerge as the gall diversity apex landscape among all biogeographic regions already investigated. Contrary to expectation, our results also support the “harsh environment hypothesis”, and unveil the Amazonian upper canopy as similar to Mediterranean vegetation habitats, hygrothermically stressed environments with leaf temperature at lethal limits and high levels of leaf sclerophylly. PMID:25551769

  10. Unexpected high diversity of galling insects in the Amazonian upper canopy: the savanna out there.

    PubMed

    Julião, Genimar R; Venticinque, Eduardo M; Fernandes, G Wilson; Price, Peter W

    2014-01-01

    A relatively large number of studies reassert the strong relationship between galling insect diversity and extreme hydric and thermal status in some habitats, and an overall pattern of a greater number of galling species in the understory of scleromorphic vegetation. We compared galling insect diversity in the forest canopy and its relationship with tree richness among upland terra firme, várzea, and igapó floodplains in Amazonia, Brazil. The soils of these forest types have highly different hydric and nutritional status. Overall, we examined the upper layer of 1,091 tree crowns. Galling species richness and abundance were higher in terra firme forests compared to várzea and igapó forests. GLM-ANCOVA models revealed that the number of tree species sampled in each forest type was determinant in the gall-forming insect diversity. The ratio between galling insect richness and number of tree species sampled (GIR/TSS ratio) was higher in the terra firme forest and in seasonally flooded igapó, while the várzea presented the lowest GIR/TSS ratio. In this study, we recorded unprecedented values of galling species diversity and abundance per sampling point. The GIR/TSS ratio from várzea was approximately 2.5 times higher than the highest value of this ratio ever reported in the literature. Based on this fact, we ascertained that várzea and igapó floodplain forests (with lower GIA and GIR), together with the speciose terra firme galling community emerge as the gall diversity apex landscape among all biogeographic regions already investigated. Contrary to expectation, our results also support the "harsh environment hypothesis", and unveil the Amazonian upper canopy as similar to Mediterranean vegetation habitats, hygrothermically stressed environments with leaf temperature at lethal limits and high levels of leaf sclerophylly.

  11. Taxonomic identity of a galling adelgid (Hemiptera: Adelgidae) from three spruce species in central Japan

    Treesearch

    Masakazu Sano; Nathan P. Havill; Kenichi Ozaki

    2011-01-01

    Gall-forming insects are commonly highly host-specific, and galling species once thought to be oligo- or polyphagous are often found to represent a complex of host-specific races or cryptic species. A recent DNA barcoding study documented that an unidentified species of the genus Adelges is a gall-former associated with four spruce species (...

  12. Two Birch Species Demonstrate Opposite Latitudinal Patterns in Infestation by Gall-Making Mites in Northern Europe

    PubMed Central

    Skoracka, Anna; Zverev, Vitali; Lewandowski, Mariusz; Zvereva, Elena L.

    2016-01-01

    Latitudinal patterns in herbivory, i.e. variations in plant losses to animals with latitude, are generally explained by temperature gradients. However, earlier studies suggest that geographical variation in abundance and diversity of gall-makers may be driven by precipitation rather than by temperature. To test the above hypothesis, we examined communities of eriophyoid mites (Acari: Eriophyoidea) on leaves of Betula pendula and B. pubescens in boreal forests in Northern Europe. We sampled ten sites for each of five latitudinal gradients from 2008–2011, counted galls of six morphological types and identified mites extracted from these galls. DNA analysis revealed cryptic species within two of six morphologically defined mite species, and these cryptic species induced different types of galls. When data from all types of galls and from two birch species were pooled, the percentage of galled leaves did not change with latitude. However, we discovered pronounced variation in latitudinal changes between birch species. Infestation by eriophyoid mites increased towards the north in B. pendula and decreased in B. pubescens, while diversity of galls decreased towards the north in B. pendula and did not change in B. pubescens. The percentage of galled leaves did not differ among geographical gradients and study years, but was 20% lower in late summer relative to early summer, indicating premature abscission of infested leaves. Our data suggest that precipitation has little effect on abundance and diversity of eriophyoid mites, and that climate warming may impose opposite effects on infestation of two birch species by galling mites, favouring B. pendula near the northern tree limit. PMID:27835702

  13. Host Genetics and Environment Drive Divergent Responses of Two Resource Sharing Gall-Formers on Norway Spruce: A Common Garden Analysis.

    PubMed

    Axelsson, E Petter; Iason, Glenn R; Julkunen-Tiitto, Riitta; Whitham, Thomas G

    2015-01-01

    A central issue in the field of community genetics is the expectation that trait variation among genotypes play a defining role in structuring associated species and in forming community phenotypes. Quantifying the existence of such community phenotypes in two common garden environments also has important consequences for our understanding of gene-by-environment interactions at the community level. The existence of community phenotypes has not been evaluated in the crowns of boreal forest trees. In this study we address the influence of tree genetics on needle chemistry and genetic x environment interactions on two gall-inducing adelgid aphids (Adelges spp. and Sacchiphantes spp.) that share the same elongating bud/shoot niche. We examine the hypothesis that the canopies of different genotypes of Norway spruce (Picea abies L.) support different community phenotypes. Three patterns emerged. First, the two gallers show clear differences in their response to host genetics and environment. Whereas genetics significantly affected the abundance of Adelges spp. galls, Sacchiphantes spp. was predominately affected by the environment suggesting that the genetic influence is stronger in Adelges spp. Second, the among family variation in genetically controlled resistance was large, i.e. fullsib families differed as much as 10 fold in susceptibility towards Adelges spp. (0.57 to 6.2 galls/branch). Also, the distribution of chemical profiles was continuous, showing both overlap as well as examples of significant differences among fullsib families. Third, despite the predicted effects of host chemistry on galls, principal component analyses using 31 different phenolic substances showed only limited association with galls and a similarity test showed that trees with similar phenolic chemical characteristics, did not host more similar communities of gallers. Nonetheless, the large genetic variation in trait expression and clear differences in how community members respond to host

  14. Gall bladder rupture associated with cholecystitis in a domestic ferret (Mustela putorius).

    PubMed

    Huynh, M; Guillaumot, P; Hernandez, J; Ragetly, G

    2014-09-01

    A six-year-old neutered female albino ferret was presented with an acute episode of lethargy and anorexia. Clinical examination revealed marked cranial abdominal pain. A severe neutrophilic leukocytosis was present. Abdominal ultrasound was consistent with a diffuse peritonitis and severe bile duct inflammation. Cytology of the abdominal effusion revealed bile peritonitis. An exploratory laparotomy was performed and the gall bladder appeared inflamed with multiple perforations. A cholecystectomy was performed. The ferret recovered without complication. Bacteriological culture of the bile and gall bladder yielded a pure growth of Pseudomonas aeruginosa. Histopathological analysis of the gall bladder and liver was consistent with a marked cholecystitis and cholangiohepatitis. On the basis of sensitivity testing, the ferret was treated with marbofloxacin for one month. No complications or reoccurrence were seen up to 1 year after the diagnosis. To the author's knowledge, this is the first report of bile peritonitis secondary to gall bladder rupture in a ferret. © 2014 British Small Animal Veterinary Association.

  15. Evolution of a complex behavior: the origin and initial diversification of foliar galling by Permian insects

    NASA Astrophysics Data System (ADS)

    Schachat, Sandra R.; Labandeira, Conrad C.

    2015-04-01

    A central notion of the early evolution of insect galling is that this unique behavior was uncommon to rare before the diversification of angiosperms 135 to 125 m.yr. ago. However, evidence accumulated during recent years shows that foliar galls were diverse and locally abundant as early as the Permian Period, 299 to 252 m.yr. ago. In particular, a diversity of leaf galling during the Early Permian has recently been documented by the plant-damage record of foliar galls and, now, our interpretation of the body-fossil record of culprit insect gallers. Small size is a prerequisite for gallers. Wing-length measurements of Permian insects indicate that several small-bodied hemipteroid lineages originated early during the Permian, some descendant lineages of which gall the leaves of seed plants to the present day. The earliest foliar gallers likely were Protopsyllidiidae (Hemiptera) and Lophioneuridae (Thripida). Much of the Early Permian was a xeric interval, and modern galls are most common in dry, extra-tropical habitats such as scrubland and deserts. Plant-damage, insect body fossils, and the paleoclimate record collectively support the ecological expansion of foliar galling during the Early Permian and its continued expansion through the Late Permian.

  16. A material based approach to creating wear resistant surfaces for hot forging

    NASA Astrophysics Data System (ADS)

    Babu, Sailesh

    Tools and dies used in metal forming are characterized by extremely high temperatures at the interface, high local pressures and large metal to metal sliding. These harsh conditions result in accelerated wear of tooling. Lubrication of tools, done to improve metal flow drastically quenches the surface layers of the tools and compounds the tool failure problem. This phenomenon becomes a serious issue when parts forged at complex and are expected to meet tight tolerances. Unpredictable and hence uncontrolled wear and degradation of tooling result in poor part quality and premature tool failure that result in high scrap, shop downtime, poor efficiency and high cost. The objective of this dissertation is to develop a computer-based methodology for analyzing the requirements hot forging tooling to resist wear and plastic deformation and wear and predicting life cycle of forge tooling. Development of such is a system is complicated by the fact that wear and degradation of tooling is influenced by not only the die material used but also numerous process controls like lubricant, dilution ratio, forging temperature, equipment used, tool geometries among others. Phenomenological models available u1 the literature give us a good thumb rule to selecting materials but do not provide a way to evaluate pits performance in field. Once a material is chosen, there are no proven approaches to create surfaces out of these materials. Coating approaches like PVD and CVD cannot generate thick coatings necessary to withstand the conditions under hot forging. Welding cannot generate complex surfaces without several secondary operations like heat treating and machining. If careful procedures are not followed, welds crack and seldom survive forging loads. There is a strong need for an approach to selectively, reliably and precisely deposit material of choice reliably on an existing surface which exhibit not only good tribological properties but also good adhesion to the substrate

  17. Wear properties of dental ceramics and porcelains compared with human enamel.

    PubMed

    D'Arcangelo, Camillo; Vanini, Lorenzo; Rondoni, Giuseppe D; De Angelis, Francesco

    2016-03-01

    Contemporary pressable and computer-aided design/manufacturing (CAD/CAM) ceramics exhibit good mechanical and esthetic properties. Their wear resistance compared with human enamel and traditional gold based alloys needs to be better investigated. The purpose of this in vitro study was to compare the 2-body wear resistance of human enamel, gold alloy, and 5 different dental ceramics, including a recently introduced zirconia-reinforced lithium silicate ceramic (Celtra Duo). Cylindrical specimens were fabricated from a Type III gold alloy (Aurocast8), 2 hot pressed ceramics (Imagine PressX, IPS e.max Press), 2 CAD/CAM ceramics (IPS e.max CAD, Celtra Duo), and a CAD/CAM feldspathic porcelain (Vitablocs Mark II) (n=10). Celtra Duo was tested both soon after grinding and after a subsequent glaze firing cycle. Ten flat human enamel specimens were used as the control group. All specimens were subjected to a 2-body wear test in a dual axis mastication simulator for 120000 loading cycles against yttria stabilized tetragonal zirconia polycrystal cusps. The wear resistance was analyzed by measuring the vertical substance loss (mm) and the volume loss (mm(3)). Antagonist wear (mm) was also recorded. Data were statistically analyzed with 1-way ANOVA tests (α=.05). The wear depth (0.223 mm) of gold alloy was the closest to that of human enamel (0.217 mm), with no significant difference (P>.05). The greatest wear was recorded on the milled Celtra Duo (wear depth=0.320 mm), which appeared significantly less wear resistant than gold alloy or human enamel (P<.05). The milled and not glazed Celtra Duo showed a small but significantly increased wear depth compared with Aurocast8 and human enamel. Wear depth and volumetric loss for the glaze-fired Celtra Duo and for the other tested ceramics did not statistically differ in comparison with the human enamel. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  18. The Effect of Coatings on the Wear Behavior of Ti6Al4V Alloy Used in Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Danışman, Ş.; Odabas, D.; Teber, M.

    2018-01-01

    The properties expected from implant materials are biocompatibility, long service life and wear resistance. The wear resistance of the implant materials varies according to the type of implant, usage area and the movement. The ability of implant material to be more compatible with biological tissues and to increase the useful life depends on the surface properties. Today many different kind of surface modification techniques are applying on medical and dental implant surfaces to improve surface specifications and wear resistance. In this study TiN, TiAlN, TiCN coatings were applied on Ti6Al4V alloy used as implant material by reactive magnetron sputtering method. The wear resistances of uncoated Ti6Al4V alloy and TiN, TiAlN, TiCN coatings were investigated at room temperature under dry conditions. The wear resistance at different load and different sliding rates were compared using an wear tester. The wear losses, wear track widths and friction coefficients of coated and uncoated Ti6Al4V alloys are taken into account for comparison. The results show that a significant improvement in wear resistance of the alloy with the coating is achieved and TiN-coated Ti6Al4V alloy has the highest wear resistance.

  19. 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.

  20. Restoration of the wear-resistant coatings on a GTE compressor airfoil shroud platform

    NASA Astrophysics Data System (ADS)

    Abraimov, N. V.; Geikin, V. A.; Chekalova, E. A.; Lukina, V. V.

    2017-06-01

    The deposition of a VT20 alloy onto the airfoil shroud platform of a compressor in an argon atmosphere and the composition, the structure, and the properties of a restored wear-resistant VK-25M coating are studied. The coating deposited onto the built-up material is found to contain (%) 3-4 C, 72-74 W, and 23-24 Co. This coating does not undergo cracking when a diamond pyramid is indented at a load of 50 kg or a diamond cone is indented at a load of 100 kg at a layer thickness of 0.15, 0.25, and 0.38 mm.

  1. Evolution of a complex behavior: the origin and initial diversification of foliar galling by Permian insects.

    PubMed

    Schachat, Sandra R; Labandeira, Conrad C

    2015-04-01

    A central notion of the early evolution of insect galling is that this unique behavior was uncommon to rare before the diversification of angiosperms 135 to 125 m.yr. ago. However, evidence accumulated during recent years shows that foliar galls were diverse and locally abundant as early as the Permian Period, 299 to 252 m.yr. ago. In particular, a diversity of leaf galling during the Early Permian has recently been documented by the plant-damage record of foliar galls and, now, our interpretation of the body-fossil record of culprit insect gallers. Small size is a prerequisite for gallers. Wing-length measurements of Permian insects indicate that several small-bodied hemipteroid lineages originated early during the Permian, some descendant lineages of which gall the leaves of seed plants to the present day. The earliest foliar gallers likely were Protopsyllidiidae (Hemiptera) and Lophioneuridae (Thripida). Much of the Early Permian was a xeric interval, and modern galls are most common in dry, extra-tropical habitats such as scrubland and deserts. Plant-damage, insect body fossils, and the paleoclimate record collectively support the ecological expansion of foliar galling during the Early Permian and its continued expansion through the Late Permian.

  2. Looking for gall bladder disease in the patient's iris.

    PubMed Central

    Knipschild, P.

    1988-01-01

    In alternative health care iridology is used as a diagnostic aid. The diagnosis of gall bladder disease was used to study its validity and interperformer consistency. The presence of an inflamed gall bladder containing gall stones is said to be easily recognised by certain signs in the lower lateral part of the iris of the right eye. Stereo colour slides were made of the right eye. Stereo colour slides were made of the right eye of 39 patients with this disease and 39 control subjects of the same sex and age. The slides were presented in a random order to five leading iridologists without supplementary information. The prevalence of the disease was estimated at 56%. The median validity was 51% with 54% sensitivity and 52% specificity. These results were close to chance validity (iota = 0.03). None of the iridologists reached a high validity. The median interperformer consistency was 60%. This was only slightly higher than chance consistency (kappa = 0.18). This study showed that iridology is not a useful diagnostic aid. PMID:3147081

  3. Looking for gall bladder disease in the patient's iris.

    PubMed

    Knipschild, P

    1988-12-17

    In alternative health care iridology is used as a diagnostic aid. The diagnosis of gall bladder disease was used to study its validity and interperformer consistency. The presence of an inflamed gall bladder containing gall stones is said to be easily recognised by certain signs in the lower lateral part of the iris of the right eye. Stereo colour slides were made of the right eye. Stereo colour slides were made of the right eye of 39 patients with this disease and 39 control subjects of the same sex and age. The slides were presented in a random order to five leading iridologists without supplementary information. The prevalence of the disease was estimated at 56%. The median validity was 51% with 54% sensitivity and 52% specificity. These results were close to chance validity (iota = 0.03). None of the iridologists reached a high validity. The median interperformer consistency was 60%. This was only slightly higher than chance consistency (kappa = 0.18). This study showed that iridology is not a useful diagnostic aid.

  4. 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

  5. Species turnover drives β-diversity patterns across multiple spatial scales of plant-galling interactions in mountaintop grasslands.

    PubMed

    Coelho, Marcel Serra; Carneiro, Marco Antônio Alves; Branco, Cristina Alves; Borges, Rafael Augusto Xavier; Fernandes, Geraldo Wilson

    2018-01-01

    This study describes differences in species richness and composition of the assemblages of galling insects and their host plants at different spatial scales. Sampling was conducted along altitudinal gradients composed of campos rupestres and campos de altitude of two mountain complexes in southeastern Brazil: Espinhaço Range and Mantiqueira Range. The following hypotheses were tested: i) local and regional richness of host plants and galling insects are positively correlated; ii) beta diversity is the most important component of regional diversity of host plants and galling insects; and iii) Turnover is the main mechanism driving beta diversity of both host plants and galling insects. Local richness of galling insects and host plants increased with increasing regional richness of species, suggesting a pattern of unsaturated communities. The additive partition of regional richness (γ) into local and beta components shows that local richnesses (α) of species of galling insects and host plants are low relative to regional richness; the beta (β) component incorporates most of the regional richness. The multi-scale analysis of additive partitioning showed similar patterns for galling insects and host plants with the local component (α) incorporated a small part of regional richness. Beta diversity of galling insects and host plants were mainly the result of turnover, with little contribution from nesting. Although the species composition of galling insects and host plant species varied among sample sites, mountains and even mountain ranges, local richness remained relatively low. In this way, the addition of local habitats with different landscapes substantially affects regional richness. Each mountain contributes fundamentally to the composition of regional diversity of galling insects and host plants, and so the design of future conservation strategies should incorporate multiple scales.

  6. Skeletotopy of the gall bladder in American mink (Mustela vision (Brisson, 1756)).

    PubMed

    Gościcka, D; Flisiński, P

    1994-01-01

    Using anatomical and radiological methods, the projection of the gall bladder was studied in relation to the vertebral column in fifty adult minks of both sexes. The gall bladder was found to be in three positions when in relation to: 1) the longitudinal axis of the vertebral column, 2) the numerical order of the vertebrae.

  7. Wear behavior of AISI 1090 steel modified by pulse plasma technique

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

    Ayday, Aysun; Durman, Mehmet

    2012-09-06

    AISI 1090 steel was pulse plasma treated (PPT) using a Molybdenum electrode. Two different pulse numbers were chosen to obtain modified layers of 20{+-}5 {mu}m thickness. The dry sliding wear studies performed on this steel with and without PPT against an alumina ball counterpart showed that the PPT improved the wear resistance. The pulse number of the PPT modified layer was found to be highly influential in imparting the wear resistance to this steel, due to enhancement of surface hardness depending on treatment time.

  8. Effect of inspiratory resistance to prolonged exercise in a hot environment wearing protective clothing

    NASA Astrophysics Data System (ADS)

    Jetté, Maurice; Quenneville, Josée; Thoden, James; Livingstone, Sydney

    1992-09-01

    The effects of inspiratory resistance on prolonged work in a hot environment wearing a nuclear, bacteriological and chemical warfare (NBCW) mask and overgarment were assessed in 10 males. Subjects walked on a treadmill at 5 km/hr, 2% gradient, until their core temperature reached 39° C or for a duration of 90 min. Rectal temperature, heart rate, ventilation, oxygen consumption and rate of perceived breathing were measured. There were no differences between break-point time without the canister (62.2 ± 21 min) and with the canister (58.9 ± 17 min). Regression analysis indicated that the mean core temperature increased by 0.02° C for every minute of work performed and heart rate by 6 beats/min for every increase of 0.2° C in core temperature. Reduction in heat transfer brought about by wearing the protective overgarment and mask with or without the canister will significantly increase core temperature and limit the performance of moderate work to approximately 1 h in a moderately fit individual.

  9. The North American gall midges (Diptera: Cecidomyiidae) of hackberries (Cannabaceae: Celtis spp.).

    Treesearch

    Raymond J. Gagne; John Moser

    2013-01-01

    Twenty-three species of gall midges occur exclusively on hackberries in North America north of Mexico. Twenty-one of them belong to the genus Celticecis and form complex, dehiscent galls on leaves and the current year's twigs. Celticecis species are definitely known only from the typical subgenus of Celtis, distributed through much of the Holarctic Region....

  10. Wear Analysis of Thermal Spray Coatings on 3D Surfaces

    NASA Astrophysics Data System (ADS)

    Tillmann, W.; Luo, W.; Selvadurai, U.

    2014-01-01

    Even though the application of thermal spray coatings on complex geometries gained a greater interest in the last decade, the effect of different geometrical features on the wear behavior is still ill-defined. In this study, the wear resistance of FTC-FeCSiMn coated 3D surfaces was investigated. The wear test was carried out by means of two innovative testing procedures. The first test is a Pin-on-Tubes test where the rotating motion is realized by a lathe chuck. The specimens in the second test were fixed on the table and a robot arm operated the pin. This wear test was applied on specimens with concave or convex surfaces. The residual stresses, which were determined by means of an incremental hole-drilling method, show a dependency on the substrate geometry. The obtained stresses were put in relation to the different radii. After the wear test, a 3D-profilometer determined the wear volume and the sections of the coatings were characterized by a scanning electron microscope. The results indicate that the wear resistance is strongly influenced by the geometry of the substrate.

  11. Sweet Tetra-Trophic Interactions: Multiple Evolution of Nectar Secretion, a Defensive Extended Phenotype in Cynipid Gall Wasps.

    PubMed

    Nicholls, James A; Melika, George; Stone, Graham N

    2017-01-01

    Many herbivores employ reward-based mutualisms with ants to gain protection from natural enemies. We examine the evolutionary dynamics of a tetra-trophic interaction in which gall wasp herbivores induce their host oaks to produce nectar-secreting galls, which attract ants that provide protection from parasitoids. We show that, consistent with other gall defensive traits, nectar secretion has evolved repeatedly across the oak gall wasp tribe and also within a single genus (Disholcaspis) that includes many nectar-inducing species. Once evolved, nectar secretion is never lost in Disholcaspis, consistent with high defensive value of this trait. We also show that evolution of nectar secretion is correlated with a transition from solitary to aggregated oviposition, resulting in clustered nectar-secreting galls, which produce a resource that ants can more easily monopolize. Such clustering is commonly seen in ant guard mutualisms. We suggest that correlated evolution between maternal oviposition and larval nectar induction traits has enhanced the effectiveness of this gall defense strategy.

  12. Patterns of cell elongation in the determination of the final shape in galls of Baccharopelma dracunculifoliae (Psyllidae) on Baccharis dracunculifolia DC (Asteraceae).

    PubMed

    Magalhães, Thiago Alves; de Oliveira, Denis Coelho; Suzuki, Aline Yasko Marinho; Isaias, Rosy Mary dos Santos

    2014-07-01

    Cell redifferentiation, division, and elongation are recurrent processes, which occur during gall development, and are dependent on the cellulose microfibrils reorientation. We hypothesized that changes in the microfibrils orientation from non-galled tissues to galled ones occur and determine the final gall shape. This determination is caused by a new tissue zonation, its hyperplasia, and relative cell hypertrophy. The impact of the insect's activity on these patterns of cell development was herein tested in Baccharopelma dracunculifoliae-Baccharis dracunculifolia system. In this system, the microfibrils are oriented perpendicularly to the longest cell axis in elongated cells and randomly in isodiametric ones, either in non-galled or in galled tissues. The isodiametric cells of the abaxial epidermis in non-galled tissues divided and elongated periclinally, forming the outer gall epidermis. The anticlinally elongated cells of the abaxial palisade layer and the isodiametric cells of the spongy parenchyma originated the gall outer cortex with hypertrophied and periclinally elongated cells. The anticlinally elongated cells of the adaxial palisade layer originated the inner cortex with hypertrophied and periclinally elongated cells in young and mature galls and isodiametric cells in senescent galls. The isodiametric cells of the adaxial epidermis elongated periclinally in the inner gall epidermis. The current investigation demonstrates the role of cellulose microfibril reorientation for gall development. Once many factors other than this reorientation act on gall development, it should be interesting to check the possible relationship of the new cell elongation patterns with the pectic composition of the cell walls.

  13. Wear Enhancement of Wheel-Rail Interaction by Ultrasonic Nanocrystalline Surface Modification Technique.

    PubMed

    Chang, Seky; Pyun, Young-Sik; Amanov, Auezhan

    2017-02-16

    In this study, an ultrasonic nanocrystalline surface modification (UNSM) technique was applied to normal and heat-treated rails made of 60 kgK steel to enhance the wear resistance of the wheel-rail interaction. The hardness and compressive residual stress values of the untreated and UNSM-treated rails were measured by the Brinell hardness tester and X-ray diffraction technique, respectively. It was found, according to the measurement results, that the hardness was increased by about 20% and 8%, whereas the compressive residual stress was induced by about 52% and 62% for the UNSM-treated normal and heat-treated rails, respectively. The UNSM-treated normal rail showed a slightly higher hardness than the heat-treated rail. The wear resistance of rails with respect to rotating speed and rolling time was assessed using a rolling contact wear (RCW) tester under dry conditions. The RCW test results revealed that the wear of the UNSM-treated rails was enhanced in comparison with those of the untreated rails. Also, the wear amount of the rails was increased with increasing the rotation speed. The UNSM-treated normal rail exhibited the highest wear resistance with respect to the rotation speed. The wear mechanisms of the rails are also discussed based on microscopic images of the worn out surfaces.

  14. Wear Enhancement of Wheel-Rail Interaction by Ultrasonic Nanocrystalline Surface Modification Technique

    PubMed Central

    Chang, Seky; Pyun, Young-Sik; Amanov, Auezhan

    2017-01-01

    In this study, an ultrasonic nanocrystalline surface modification (UNSM) technique was applied to normal and heat-treated rails made of 60 kgK steel to enhance the wear resistance of the wheel-rail interaction. The hardness and compressive residual stress values of the untreated and UNSM-treated rails were measured by the Brinell hardness tester and X-ray diffraction technique, respectively. It was found, according to the measurement results, that the hardness was increased by about 20% and 8%, whereas the compressive residual stress was induced by about 52% and 62% for the UNSM-treated normal and heat-treated rails, respectively. The UNSM-treated normal rail showed a slightly higher hardness than the heat-treated rail. The wear resistance of rails with respect to rotating speed and rolling time was assessed using a rolling contact wear (RCW) tester under dry conditions. The RCW test results revealed that the wear of the UNSM-treated rails was enhanced in comparison with those of the untreated rails. Also, the wear amount of the rails was increased with increasing the rotation speed. The UNSM-treated normal rail exhibited the highest wear resistance with respect to the rotation speed. The wear mechanisms of the rails are also discussed based on microscopic images of the worn out surfaces. PMID:28772549

  15. Induction of Crown Gall on Carrot Slices.

    ERIC Educational Resources Information Center

    Babich, H.; Fox, K. D.

    1998-01-01

    Argues that the transfer of plasmid from a bacterium to a plant cell has received little attention. Presents an experiment for studying this type of genetic transformation using the causative agent of crown gall, a malignant plant tumor. (DDR)

  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. Enhanced wear performance of ultra high molecular weight polyethylene crosslinked by organosilane.

    PubMed

    Tang, C Y; Xie, X L; Wu, X C; Li, R K Y; Mai, Y W

    2002-11-01

    Ultra high molecular weight polyethylene (UHMWPE) crosslinked by organosilane was thermal compression molded. The organosilane used was the tri-ethyloxyl vinyl silane. Its gelation, melting behavior, crystallinity, mechanical and wear-resisting properties were systematically investigated. The results showed that the gel ratio of UHMWPE increases with the incorporation of organosilane. At a low content of organosilane, the melting point and crystallinity of the crosslinked UHMWPE increase, and hence the mechanical and wear-resisting properties are improved. However, at a high content of organosilane, these performances of the crosslinked UHMWPE become worse. At 0.4 phr silane, the wear resistance of crosslinked UHMWPE reaches its optimum value.

  18. Franz Joseph Gall and music: the faculty and the bump.

    PubMed

    Eling, Paul; Finger, Stanley; Whitaker, Harry

    2015-01-01

    The traditional story maintains that Franz Joseph Gall's (1758-1828) scientific program began with his observations of schoolmates with bulging eyes and good verbal memories. But his search to understand human nature, in particular individual differences in capacities, passions, and tendencies, can also be traced to other important observations, one being of a young girl with an exceptional talent for music. Rejecting contemporary notions of cognition, Gall concluded that behavior results from the interaction of a limited set of basic faculties, each with its own processes for perception and memory, each with its own territory in both cerebral or cerebellar cortices. Gall identified 27 faculties, one being the sense of tone relations or music. The description of the latter is identical in both his Anatomie et Physiologie and Sur les Fonctions du Cerveau et sur Celles de Chacune de ses Parties, where he provided positive and negative evidences and discussed findings from humans and lower animals, for the faculty. The localization of the cortical faculty for talented musicians, he explained, is demonstrated by a "bump" on each side of the skull just above the angle of the eye; hence, the lower forehead of musicians is broader or squarer than in other individuals. Additionally, differences between singing and nonsinging birds also correlate with cranial features. Gall even brought age, racial, and national differences into the picture. What he wrote about music reveals much about his science and creative thinking. © 2015 Elsevier B.V. All rights reserved.

  19. Checklist of host plants of insect galls in the state of Goiás in the Midwest Region of Brazil.

    PubMed

    de Araújo, Walter Santos; Porfírio Júnior, Eder Dasdoriano; Ribeiro, Bárbara Araújo; Silva, Taiza Moura; Silva, Elienai Cândida E; Guilherme, Frederico Augusto Guimarães; Scareli-Santos, Claudia; Dos Santos, Benedito Baptista

    2015-01-01

    Surveys of host plants of insect galls have been performed in different regions of Brazil. The knowledge of species of host plants of insect galls is fundamental to further studies of plant-galling insect interactions. However, a list of host plant species of gall-inducing insects has not yet been compiled for the flora of the Midwest Region of Brazil. We provide a compilation of the plant species reported to host insect galls in the Cerrado of the state of Goiás in the Midwest Region of Brazil. Altogether we found records for 181 species of 47 families of host plants, which hosted 365 distinct gall morphotypes.

  20. Galle Crater

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 19 June 2002) The Science This image is of part of Galle Crater, located at 51.9S, 29.5W. This image was taken far enough south and late enough into the southern hemisphere fall to catch observe water ice clouds partially obscuring the surface. The most striking aspect of the surface is the dissected layered unit to the left in the image. Other areas also appear to have layering, but they are either more obscured by clouds or are less well defined on the surface. The layers appear to be mostly flat lying and layer boundaries appear as topographic lines would on a map, but there are a few areas where it appears that these layers have been deformed to some level. Other areas of the image contain rugged, mountainous terrain as well as a separate pitted terrain where the surface appears to be a separate unit from the mountains and the layered terrain. The Story Galle Crater is officially named after a German astronomer who, in 1846, was the first to observe the planet Neptune. It is better known, however, as the 'Happy Face Crater.' The image above focuses on too small an area of the crater to see its beguiling grin, but you can catch the rocky line of a 'half-smile' in the context image to the right (to the left of the red box). While water ice clouds make some of the surface harder to see, nothing detracts from the fabulous layering at the center left-hand edge of the image. If you click on the above image, the scalloped layers almost look as if a giant knife has swirled through a landscape of cake frosting. These layers, the rugged, mountains near them, and pits on the surface (upper to middle section of the image on the right-hand side) all create varying textures on the crater floor. With such different features in the same place, geologists have a lot to study to figure out what has happened in the crater since it formed.

  1. Gall bladder mucoceles and their association with endocrinopathies in dogs: a retrospective case-control study.

    PubMed

    Mesich, M L L; Mayhew, P D; Paek, M; Holt, D E; Brown, D C

    2009-12-01

    To investigate the relationship between endocrinopathies and diagnosis of gall bladder mucocele in dogs via a retrospective case-control study. Records of 78 dogs with a surgical or ultrasonographic diagnosis of gall bladder mucocele were examined for the presence or absence of hyperadrenocorticism, hypothyroidism and diabetes mellitus. Two age- and breed-matched controls for each gall bladder mucocele dog (156 total control dogs) were examined for the same concurrent diseases. A matched case-control analysis was performed using conditional logistic regression. The odds of mucocele in dogs with hyperadrenocorticism were 29 times that of dogs without hyperadrenocorticism (P=0.001; 95 per cent CI 3.8, 219.9). No difference was found between dogs with and without diabetes mellitus. Although a significant association was found between gall bladder mucocele and hypothyroidism, potential observation bias was also identifi ed. Hyperadrenocorticoid dogs that were presented for acute illness with laboratory evidence of hepatobiliary disease should undergo evaluation for the presence of a biliary mucocele. Dogs diagnosed with a gall bladder mucocele should be screened for concurrent hyperadrenocorticism if clinical suspicion exists.

  2. Improved Dental Implant Drill Durability and Performance Using Heat and Wear Resistant Protective Coatings.

    PubMed

    Er, Nilay; Alkan, Alper; Ilday, Serim; Bengu, Erman

    2018-06-01

    The dental implant drilling procedure is an essential step for implant surgery, and frictional heat in bone during drilling is a key factor affecting the success of an implant. The aim of this study was to increase the dental implant drill lifetime and performance by using heat- and wear-resistant protective coatings to decrease the alveolar bone temperature caused by the dental implant drilling procedure. Commercially obtained stainless steel drills were coated with titanium aluminum nitride, diamond-like carbon, titanium boron nitride, and boron nitride coatings via magnetron-sputter deposition. Drilling was performed on bovine femoral cortical bone under the conditions mimicking clinical practice. Tests were performed under water-assisted cooling and under the conditions when no cooling was applied. Coated drill performances and durabilities were compared with those of three commonly used commercial drills with surfaces made from zirconia, black diamond. and stainless steel. Protective coatings with boron nitride, titanium boron nitride, and diamond-like carbon have significantly improved drill performance and durability. In particular, boron nitride-coated drills have performed within safe bone temperature limits for 50 drillings even when no cooling is applied. Titanium aluminium nitride coated drills did not show any improvement over commercially obtained stainless steel drills. Surface modification using heat- and wear-resistant coatings is an easy and highly effective way to improve implant drill performance and durability, which can improve the surgical procedure and the postsurgical healing period. The noteworthy success of different types of coatings is novel and likely to be applicable to various other medical systems.

  3. 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.

  4. 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.

  5. Checklist of host plants of insect galls in the state of Goiás in the Midwest Region of Brazil

    PubMed Central

    Porfírio Júnior, Eder Dasdoriano; Ribeiro, Bárbara Araújo; Silva, Taiza Moura; Silva, Elienai Cândida e; Guilherme, Frederico Augusto Guimarães; Scareli-Santos, Claudia; dos Santos, Benedito Baptista

    2015-01-01

    Abstract Background Surveys of host plants of insect galls have been performed in different regions of Brazil. The knowledge of species of host plants of insect galls is fundamental to further studies of plant-galling insect interactions. However, a list of host plant species of gall-inducing insects has not yet been compiled for the flora of the Midwest Region of Brazil. New information We provide a compilation of the plant species reported to host insect galls in the Cerrado of the state of Goiás in the Midwest Region of Brazil. Altogether we found records for 181 species of 47 families of host plants, which hosted 365 distinct gall morphotypes. PMID:26696767

  6. Xanthogranulomatous cholecystitis: differentiation from associated gall bladder carcinoma.

    PubMed

    Rao, R V Raghavendra; Kumar, Ashok; Sikora, Sadiq S; Saxena, Rajan; Kapoor, Vinay K

    2005-01-01

    Xanthogranulomatous cholecystitis (XGC) is a destructive form of chronic cholecystitis. In some patients it coexists with gall bladder carcinoma (GBC) and is often difficult to differentiate between the two. Present study was performed with an aim to identify differentiating features of XGC and those of XGC with associated Gall bladder carcinoma (XGC ass. GBC). A retrospective analysis of prospectively maintained data of 4800 cholecystectomies performed from January 1988 to December 2003 was carried out. On histopathology 453 cholecystectomy specimens revealed XGC. These patients were divided into two groups, those with associated GBC (n=26) and those without GBC (n=427). Clinical, radiological and operative findings were compared in these two groups. P value of < 0.05 was considered statistically significant. The incidence of associated GBC in present series was 6%. XGC patients with associated GBC, at presentation were older than those with XGC alone and there was male preponderance. XGC patients with associated GBC were more likely to present with anorexia, weight loss, palpable lump and jaundice. Gall stones were present in majority of patients in both the groups. GB wall thickening, GB mass, enlarged abdominal lymph nodes may be found on imaging in both the groups but more so in patients with associated GBC. Both preoperative FNAC and peroperative FNAC/imprint cytology failed to reveal the associated GBC with XGC in some patients.

  7. Sensitivity of Dielectric Properties to Wear Process on Carbon Nanofiber/High-Density Polyethylene Composites.

    PubMed

    Liu, Tian; Wood, Weston; Zhong, Wei-Hong

    2011-12-01

    We examined the correlation of wear effects with dielectric properties of carbon nanofibers (CNFs; untreated and organosilane-treated)-reinforced high-density polyethylene (HDPE) composites. Wear testing for the nanocomposites over up to 120 h was carried out, and then, dielectric permittivity and dielectric loss factor of the polymer composites with the increased wear time were studied. Scanning electron microscope and optical microscope observations were made to analyze the microstructure features of the nanocomposites. The results reveal that there exist approximate linear relationships of permittivity with wear coefficient for the nanocomposites. Composites containing silanized CNFs with the sufficiently thick coating exhibited high wear resistance. The change in permittivity was more sensitive to the increased wear coefficient for the nanocomposites with lower wear resistance. This work provides potential for further research on the application of dielectric signals to detect the effects of wear process on lifetime of polymeric materials.

  8. Evaluation of Wear Resistance of Friction Materials Prepared by Granulation.

    PubMed

    Ma, Yunhai; Liu, Yucheng; Menon, Carlo; Tong, Jin

    2015-10-21

    The tribological properties of friction materials prepared by hot-pressing pellets of different sizes were experimentally investigated. Friction and wear tests of the specimens were performed and morphological analysis was carried out by investigating images acquired with both scanning electron and confocal laser microscopes. The highest friction coefficient of friction materials was obtained with pellets having 1-5 mm size. The lowest wear rate was obtained with pellets having 8-10 mm size. Specimens processed by mixing pellets of different sizes had the highest density and the lowest roughness and were the least expensive to fabricate. The results show that granulation generally enabled increasing the friction coefficient, decreasing the wear rate, and reducing the number of defects on the surface of friction materials.

  9. 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.

  10. Wear behaviour of wear-resistant adaptive nano-multilayered Ti-Al-Mo-N coatings

    NASA Astrophysics Data System (ADS)

    Sergevnin, V. S.; Blinkov, I. V.; Volkhonskii, A. O.; Belov, D. S.; Kuznetsov, D. V.; Gorshenkov, M. V.; Skryleva, E. A.

    2016-12-01

    Coating samples in the Ti-Al-Mo-N system were obtained by arc-PVD method at variable bias voltage Ub applied to the substrate, and the partial pressure of nitrogen P(N2) used as a reaction gas. The deposited coatings were characterized by a nanocrystalline structure with an average grain size of 30-40 nm and multilayered architecture with alternating layers of (Ti,Al)N nitride and Mo-containing phases with a thickness comparable to the grain size. Coatings of (Ti,Al)N-Mo-Mo2N and (Ti,Al)N-Mo2N compositions were obtained by changing deposition parameters. The obtained coatings had hardness of 40 GPa and the relative plastic deformation under microindentation up to 60%. (Ti,Al)N-Mo2N coatings demonstrated better physicomechanical characteristics, showing high resistance to crack formation and destruction through the plastic deformation mechanism without brittle fracturing, unlike (Ti,Al)N-Mo-Mo2N. The friction coefficient of the study coatings (against Al2O3 balls under dry condition using a pin-on-disc method) reached the values of 0.35 and 0.5 at 20 °C and 500 °C respectively, without noticeable wear within this temperature range. These tribological properties were achieved by forming MoO3 acting as a solid lubricant. At higher temperatures the deterioration in the tribological properties is due to the high rate of MoO3 sublimation from friction surfaces.

  11. [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.

  12. Microstructure and wear resistance of one-step in-situ synthesized TiN/Al composite coatings on Ti6Al4V alloy by a laser nitriding process

    NASA Astrophysics Data System (ADS)

    Fu, Yao; Zhang, Xian-Cheng; Sui, Jian-Feng; Tu, Shan-Tung; Xuan, Fu-Zhen; Wang, Zheng-Dong

    2015-04-01

    The aim of this paper was to develop a one-step in situ method to synthesize the TiN reinforced Al metallic matrix composite coatings on Ti6Al4V alloy. In this method, the Al powder and nitrogen gas were simultaneously fed into feeding nozzle during a laser nitriding process. The microstructure, microhardness and sliding wear resistance of TiN/Al coatings synthesized at different laser powers in laser nitriding were investigated. Results showed that the crack- and pore-free coatings can be made through the proposed method. However, the morphologies and distribution of TiN dendrites and wear resistance of coatings were strongly dependent on laser power used in nitriding. With increasing the laser power, the amount and density of massive TiN dendritic structure in the coating decreased and the elongated and narrow dendrites increased, leading to the increment of wear resistance of coating. When the laser power is high, the convectional flow pattern of the melt pool can be seen near the bottom of pool.

  13. Optimization of the laser remelting process for HVOF-sprayed Stellite 6 wear resistant coatings

    NASA Astrophysics Data System (ADS)

    Ciubotariu, Costel-Relu; Frunzăverde, Doina; Mărginean, Gabriela; Șerban, Viorel-Aurel; Bîrdeanu, Aurel-Valentin

    2016-03-01

    Cobalt base alloys are used in all industrial areas due to their excellent wear resistance. Several studies have shown that Stellite 6 coatings are suitable not only for protection against sliding wear, but also in case of exposure to impact loading. In this respect, a possible application is the protection of hydropower plant components affected by cavitation. The main problem in connection with Stellite 6 is the deposition procedure of the protective layers, both welding and thermal spraying techniques requesting special measures in order to prevent the brittleness of the coating. In this study, Stellite 6 layers were HVOF thermally sprayed on a martensitic 13-4 stainless steel substrate, as usually used for hydraulic machinery components. In order to improve the microstructure of the HVOF-sprayed coatings and their adhesion to the substrate, laser remelting was applied, using a TRUMPF Laser type HL 124P LCU and different working parameters. The microstructure of the coatings, obtained for various remelting conditions, was evaluated by light microscopy, showing the optimal value of the pulse power, which provided a homogenous Stellite 6 layer with good adhesion to the substrate.

  14. 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.

  15. Wear Resistance of Steels with Surface Nanocrystalline Structure Generated by Mechanical-Pulse Treatment.

    PubMed

    Nykyforchyn, Hryhoriy; Kyryliv, Volodymyr; Maksymiv, Olha

    2017-12-01

    The influence of the surface mechanical-pulse treatment based on high-speed friction with a rapid cooling by the technological environment on the wear resistance of medium- and high-carbon steels was considered. The treatment due to a severe plastic deformation enabled obtaining the nanocrystalline structure with a grain size of 14-40 nm. A high positive effect of this treatment was obtained not only because of metal nanocrystallization but also thanks to other factors, namely, structural-phase transformations, carbon saturation of the surface due to decomposition of the coolant and the friction coefficient decrease. Higher carbon content leads to better strengthening of the surface, and its microhardness can reach 12 GPa.

  16. Divergent host-plant use promotes reproductive isolation among cynipid gall wasp populations

    PubMed Central

    Egan, Scott P.; Hood, Glen R.; Feder, Jeff L.; Ott, James R.

    2012-01-01

    Ecological speciation occurs when reproductive isolation evolves as a consequence of divergent natural selection among environments. A direct prediction of this process is that ecologically divergent pairs of populations will exhibit greater reproductive isolation than ecologically similar pairs of populations. By comparing allopatric populations of the cynipid gall wasp Belonocnema treatae infesting Quercus virginiana and Quercus geminata, we tested the role that divergent host use plays in generating ecological divergence and sexual isolation. We found differences in body size and gall structure associated with divergent host use, but no difference in neutral genetic divergence between populations on the same or different host plant. We observed significant assortative mating between populations from alternative host plants but not between allopatric populations on the same host plant. Thus, we provide evidence that divergent host use promotes speciation among gall wasp populations. PMID:22337505

  17. Characteristics of highly cross-linked polyethylene wear debris in vivo

    PubMed Central

    Baxter, Ryan M.; MacDonald, Daniel W.; Kurtz, Steven M.; Steinbeck, Marla J.

    2014-01-01

    Despite the widespread implementation of highly cross-linked polyethylene (HXLPE) liners to reduce the clinical incidence of osteolysis, it is not known if the improved wear resistance will outweigh the inflammatory potential of HXLPE wear debris generated in vivo. Thus, we asked: What are the differences in size, shape, number, and biological activity of polyethylene wear particles obtained from primary total hip arthroplasty revision surgery of conventional polyethylene (CPE) versus remelted or annealed HXLPE liners? Pseudocapsular tissue samples were collected from revision surgery of CPE and HXLPE (annealed and remelted) liners, and digested using nitric acid. The isolated polyethylene wear particles were evaluated using scanning electron microscopy. Tissues from both HXLPE cohorts contained an increased percentage of submicron particles compared to the CPE cohort. However, the total number of particles was lower for both HXLPE cohorts, as a result there was no significant difference in the volume fraction distribution and specific biological activity (SBA; the relative biological activity per unit volume) between cohorts. In contrast, based on the decreased size and number of HXLPE wear debris there was a significant decrease in total particle volume (mm3/g of tissue). Accordingly, when the SBA was normalized by total particle volume (mm3/gm tissue) or by component wear volume rate (mm3/year), functional biological activity of the HXLPE wear debris was significantly decreased compared to the CPE cohort. Indications for this study are that the osteolytic potential of wear debris generated by HXLPE liners in vivo is significantly reduced by improvements in polyethylene wear resistance. PMID:23436587

  18. Clinical pulmonary function and industrial respirator wear

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

    Raven, P.B.; Moss, R.F.; Page, K.

    1981-12-01

    This investigation was the initial step in determining a clinical pulmonary test which could be used to evaluate workers as to their suitability to industrial respirator wear. Sixty subjects, 12 superior, 37 normal, and 11 moderately impaired with respect to lung function tests were evaluated with a battery of clinical pulmonary tests while wearing an industrial respirator. The respirator was a full-face mask (MSA-Ultravue) demand breathing type equipped with an inspiratory resistance of 85mm H/sub 2/O at 85 L/min air flow and an expiratory resistance of 25mm H/sub 2/O at 85 L/min air flow. Comparisons of these tests were mademore » between the three groups of subjects both with and without a respirator. It appears that those lung tests which measure the flow characteristics of the lung especially those that are effort dependant are more susceptible to change as a result of respirator wear. Hence, the respirator affects the person with superior lung function to a greater degree than the moderately impaired person. It was suggested that the clinical test of 15 second maximum voluntary ventilations (MVV./sub 25/) may be the test of choice for determining worker capability in wearing an industrial respirator.« less

  19. 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.

  20. Microstructures and Hardness/Wear Performance of High-Carbon Stellite Alloys Containing Molybdenum

    NASA Astrophysics Data System (ADS)

    Liu, Rong; Yao, J. H.; Zhang, Q. L.; Yao, M. X.; Collier, Rachel

    2015-12-01

    Conventional high-carbon Stellite alloys contain a certain amount of tungsten which mainly serves to provide strengthening to the solid solution matrix. These alloys are designed for combating severe wear. High-carbon molybdenum-containing Stellite alloys are newly developed 700 series of Stellite family, with molybdenum replacing tungsten, which are particularly employed in severe wear condition with corrosion also involved. Three high-carbon Stellite alloys, designated as Stellite 706, Stellite 712, and Stellite 720, with different carbon and molybdenum contents, are studied experimentally in this research, focusing on microstructure and phases, hardness, and wear resistance, using SEM/EDX/XRD techniques, a Rockwell hardness tester, and a pin-on-disk tribometer. It is found that both carbon and molybdenum contents influence the microstructures of these alloys significantly. The former determines the volume fraction of carbides in the alloys, and the latter governs the amount of molybdenum-rich carbides precipitated in the alloys. The hardness and wear resistance of these alloys are increased with the carbide volume fraction. However, with the same or similar carbon content, high-carbon CoCrMo Stellite alloys exhibit worse wear resistance than high-carbon CoCrW Stellite alloys.

  1. 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.

  2. 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.

  3. Influence of Carbon interstitials to Ti1-xMexN (Me = Zr, Al, Cr) coatings by pulsed laser ablation on wear resistance

    NASA Astrophysics Data System (ADS)

    Jeon, Seol; Hong, Eunpyo; Kwon, Se-Hun; Lee, Heesoo

    2018-06-01

    The wear resistance of Ti1-xMexN (Me = Zr, Al, Cr) coatings by the laser carburization process was investigated in terms of local atomic structural changes. The repeated pulsed laser ablation was performed to the Ti1-xMexN coating surfaces after Graphite paste was covered. The friction coefficients of the coating specimens were decreased from ∼0.7 to 0.2, and the formation of cracks and debris was suppressed by implementing the laser ablation process. ToF-SIMS depth profiles showed that the laser carburization helps Carbon penetrate into the coating layer as deep as ∼20 nm below its surface. XPS and XAFS analyses revealed that the improvement of the wear resistance of the coatings was achieved not by formation of TiC or ZrC lattices on the coatings surfaces but by Carbon interstitials to the Ti1-xMexN lattices.

  4. A massive expansion of effector genes underlies gall-formation in the wheat pest Mayetiola destructor

    USDA-ARS?s Scientific Manuscript database

    The mechanisms arthropods use to induce plant gall formation are poorly understood. However, there is growing evidence that effector proteins are involved. To examine this hypothesis, we sequenced the genome of the Hessian fly (Mayetiola destructor, M. des), an obligate plant parasitic gall midge an...

  5. 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.

  6. A NEW SPECIES OF INVASIVE GALL WASP (HYMENOPTERA: EULOPHIDAE: TETRASTICHINAE) ON BLUE GUM (EUCALYPTUS GLOBULUS) IN CALIFORNIA

    USDA-ARS?s Scientific Manuscript database

    The blue gum gall wasp, Selitrichodes globulus La Salle & Gates (Hymenoptera: Eulophidae: Tetrastichinae), is described as an invasive gall inducer on blue gum, Eucalyptus globulus (Myrtaceae), in California....

  7. Influence of Heat Treatment on Fracture Toughness and Wear Resistance of Nicral-Zro2 Multilayered Thermal Barrier Coating

    NASA Astrophysics Data System (ADS)

    Ye, Zibo; Wang, Guanghong

    2018-04-01

    The chemical composition and fracture toughness of thermal barrier coatings (TBCs) before and after heat treatment were characterized, and the cracks around the interface between the coating and the substrate could be successfully eliminated and meanwhile the porosity of the coatings tended to reduce. The XRD analysis revealed the coatings were composed of non-transformable tetragonal t' phase of ZrO2 and γ -(Ni, Cr) with minor Ni3Al (γ') precipitates. Additionally, the relationship between the heat treatment and wear resistance was systematically studied. The results indicated that both the hardness and fracture toughness increased after quenching process. The oxidation wear became more prominent after heat treatment, which probably resulted from the better bonding strength of coatings. Dense and homogeneous microstructure introduced by vacuum oil-quenching improved stabilization of the weight gain during thermal cycle test.

  8. Screening Pinus sylvestris grown for the production of Christmas trees for resistance to western gall rust Peridermium harknessii using different sources of aeciospores

    Treesearch

    Todd A. Burnes; Jennifer Juzwik; Robert A. Blanchette

    1999-01-01

    Results showed a moderate to high susceptibility of Pinus sylvestris to western gall rust Peridermium barknessii, from Pinna sylvestris in Michigan and Pinna banksiana in Minnesota. In general, Pinus sylvestris seed sources were more susceptible to aeciospores collected from...

  9. Systemically Applied Insecticides for Treatment of Erythrina Gall Wasp, Quadrastichus erythrinae Kim (Hymenoptera: Eulophidae)

    Treesearch

    Joseph J. Doccola; Sheri L. Smith; Brian L. Strom; Arthur C. Medeiros; Erica von Allmen

    2009-01-01

    The erythrina gall wasp (EGW), believed native to Africa, is a recently described species and now serious invasive pest of Erythrina (coral trees) in tropical and subtropical locales. Erythrina are favored ornamental and landscape trees, as well as native members of threatened ecosystems. The EGW is a tiny, highly mobile, highly invasive wasp that deforms (galls) host...

  10. Microstructure and properties of laser-clad high-temperature wear-resistant alloys

    NASA Astrophysics Data System (ADS)

    Yang, Yongqiang

    1999-02-01

    A 2-kW CO 2 laser with a powder feeder was used to produce alloy coatings with high temperature-wear resistance on the surface of steel substrates. To analyze the microstructure and microchemical composition of the laser-clad layers, a scanning electron microscope (SEM) equipped with an energy dispersive X-ray microanalysis system was employed. X-ray diffraction techniques were applied to characterize the phases formed during the cladding process. The results show that the microstructure of the cladding alloy consists mainly of many dispersed particles (W 2C, (W,Ti)C 1- x, WC), a lamellar eutectic carbide M 12C, and an (f.c.c) matrix. Hardness tested at room and high temperature showed that the laser-clad zone has a moderate room temperature hardness and relatively higher elevated temperature hardness. The application of the laser-clad layer to a hot tool was very successful, and its operational life span was prolonged 1 to 4 times.

  11. 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.

  12. Sliding wear and friction behaviour of zircaloy-4 in water

    NASA Astrophysics Data System (ADS)

    Sharma, Garima; Limaye, P. K.; Jadhav, D. T.

    2009-11-01

    In water cooled nuclear reactors, the sliding of fuel bundles in fuel channel handling system can lead to severe wear and it is an important topic to study. In the present study, sliding wear behaviour of zircaloy-4 was investigated in water (pH ˜ 10.5) using ball-on-plate sliding wear tester. Sliding wear resistance zircaloy-4 against SS 316 was examined at room temperature. Sliding wear tests were carried out at different load and sliding frequencies. The coefficient of friction of zircaloy-4 was also measured during each tests and it was found to decrease slightly with the increase in applied load. The micro-mechanisms responsible for wear in zircaloy-4 were identified to be microcutting, micropitting and microcracking of deformed subsurface zones in water.

  13. Antioxidant activities of ficus glomerata (moraceae) leaf gall extracts

    PubMed Central

    Eshwarappa, Ravi Shankara Birur; Iyer, Shanthi; Subaramaihha, Sundara Rajan; Richard, S Austin; Dhananjaya, Bhadrapura Lakkappa

    2015-01-01

    An excess production or decreased scavenging of reactive oxygen species (ROS) has been implicated in the pathogenesis of diverse metabolic disorders such as diabetes, cancer, atherosclerosis and neurodegeneration. Hence the antioxidant therapy has gained an utmost importance in the treatment of such diseases linked to free radicals. The medicinal properties of plants have been investigated and explored for their potent antioxidant activities to counteract metabolic disorders. This research highlights the chemical composition and antioxidant potential of leaf gall extracts (aqueous and methanol) of Ficus glomerata (F. glomerata), which is extensively used in the preparation of traditional medications to treat various metabolic diseases. The presences of phenolics, flavonoids, phytosterols, terpenoids and reducing sugars were identified in both the extracts. In comparison to the aqueous extract, the methanol extract had the highest total phenolic and flavonoid content at 370 ± 3.2 mg of gallic acid equivalent per gram of dry weight (mg GAE/g dw) and 155 ± 3.2 mg of quercetin equivalent per gram of dry weight (mg QUE/g dw), respectively. The antioxidant activities of leaf gall extracts were examined using diphenylpicrylhydrazyl (DPPH), Nitric oxide scavenging, hydroxyl scavenging and ferric reducing power (FRAP) methods. In all the methods, the methanolic extract showed higher antioxidant potential than the aqueous extract. A higher content of both total phenolics and flavonoids were found in the methanolic extract and the significantly high antioxidant activity can be positively correlated to the high content of total polyphenols/flavonoids of the methanol extract. The results of this study confirm the folklore use of F. glomerata leaf gall extracts as a natural antioxidant and justify its ethnobotanical use. Further, the results of antioxidant properties encourage the use of F. glomerata leaf gall extracts for medicinal health, functional food and nutraceuticals

  14. 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

  15. Toward Zero Micro/Macro-Scale Wear Using Periodic Nano-Layered Coatings.

    PubMed

    Penkov, Oleksiy V; Devizenko, Alexander Yu; Khadem, Mahdi; Zubarev, Evgeniy N; Kondratenko, Valeriy V; Kim, Dae-Eun

    2015-08-19

    Wear is an important phenomenon that affects the efficiency and life of all moving machines. In this regard, extensive efforts have been devoted to achieve the lowest possible wear in sliding systems. With the advent of novel materials in recent years, technology is moving toward realization of zero wear. Here, we report on the development of new functional coatings comprising periodically stacked nanolayers of amorphous carbon and cobalt that are extremely wear resistant at the micro and macro scale. Because of their unique structure, these coatings simultaneously provide high elasticity and ultrahigh shear strength. As a result, almost zero wear was observed even after one million sliding cycles without any lubrication. The wear rate was reduced by 8-10-fold compared with the best previously reported data on extremely low wear materials.

  16. Friction and fretting wear characteristics of different diamond-like carbon coatings against alumina in water-lubricated fretting conditions.

    PubMed

    Watabe, Tsukasa; Amanov, Auezhan; Tsuboi, Ryo; Sasaki, Shinya

    2013-12-01

    Diamond-like carbon (DLC) coatings typically show low friction and high wear resistance. In this study, the friction and fretting wear characteristics of PVD, CVD and CVD-Si DLC coatings were investigated against an alumina (Al2O3) ball under water-lubricated fretting conditions. The objective of this study is to investigate and compare the friction and fretting wear characteristics of those DLC coatings at various fretting frequencies. The test results showed that the PVD DLC coating led to a lower friction coefficient and a higher resistance to fretting wear compared to those of the CVD and CVD-Si DLC coatings. However, the CVD DLC coating showed that the fretting wear resistance decreases with increasing frequency, while no significant difference in fretting wear resistances of the PVD and CVD-Si DLC coatings was observed. Quantitative surface analyses of the specimens were performed using an energy dispersive spectroscopy (EDS), a laser scanning microscope (LSM), a scanning electron microscope (SEM), an atomic force microscope (AFM) and the Raman spectroscopy.

  17. Effects of bionic units on the fatigue wear of gray cast iron surface with different shapes and distributions

    NASA Astrophysics Data System (ADS)

    Chen, Zhi-kai; Lu, Shu-chao; Song, Xi-bin; Zhang, Haifeng; Yang, Wan-shi; Zhou, Hong

    2015-03-01

    To improve the fatigue wear resistance of gray cast iron (GCI), GCI samples were modified by a laser to imitate the unique structure of some soil animals alternating between soft and hard phases; the hard phase resists the deformation and the soft phase releases the deformation. Using the self-controlled fatigue wear test method, the fatigue wear behaviors of treated and untreated samples were investigated and compared experimentally. The results show that the bionic non-smooth surface obtains a beneficial effect on improving the fatigue wear resistance of a sample, and the fatigue wear resistance of the bionic sample assembled with reticulate units (60°+0°), whose mass loss was reduced by 62%, was superior to the others. Meanwhile, a finite element (FE) was used to simulate the compression and the distributions of strain and stress on the non-smooth surface was inferred. From these results, we understood that the functions of the bionic unit such as reducing strain and stress, and also obstructing the closure and propagation of cracks were the main reasons for improving the fatigue wear property of GCI.

  18. Wear resistance and friction reduction in acrylo nitrile butadiene rubber through hybrid combination of graphite flakes and nano tungsten disulphide

    NASA Astrophysics Data System (ADS)

    Agrawal, Neha; Pandey, Akanksha; Parihar, A. S.; Mishra, A. K.; Gandhi, M. N.; Bhattacharyya, A. R.; Mukhopadhyay, K.; Prasad, N. E.

    2016-05-01

    Friction and wear have considerable role in the life span of two interacting parts. Incorporation of nanofillers in polymers/elastomers matrix causes commendable changes in its tribologicalproperties. The main purpose of this work is to reduce the coefficient of friction and wear rate of Acrylo Nitrile Butadiene rubber (NBR). To achieve such objective traditionally well knownlubricants graphite(G), tungsten disulphide (WS2) and there hybrid combination was incorporated in NBR matrix. Effect of applied load (force) and concentration of fillers on tribological properties of NBR had been studied. The filler incorporation enhanced the hardnessby 8%, showed resistance to hydraulic oil and aging effect also got improved significantly. A particular optimized concentration of NBR with hybrid combination of 2% WS2 and 4% Graphite showed minimum coefficient of friction as well as wear rate. A hypothesis could be attributed that similar lamellar structure of WS2 and Graphite along with formation of a stable nanoscale disulfide tribofilmcould result in lowering of friction. These substantially improved properties of nanoreinforced rubber materials would definitely pave promising path for plethora of potential technological applications.

  19. Fretting wear study of surface modified Ni-Ti shape memory alloy.

    PubMed

    Tan, L; Crone, W C; Sridharan, K

    2002-05-01

    A combination of shape memory characteristics, pseudoelasticity, and good damping properties make near-equiatomic nickel-titanium (Ni-Ti) alloy a desirable candidate material for certain biomedical device applications. The alloy has moderately good wear resistance, however, further improvements in this regard would be beneficial from the perspective of reducing wear debris generation, improving biocompatibility, and preventing failure during service. Fretting wear tests of Ni-Ti in both austenitic and martensitic microstructural conditions were performed with the goal of simulating wear which medical devices such as stents may experience during surgical implantation or service. The tests were performed using a stainless steel stylus counter-wearing surface under dry conditions and also with artificial plasma containing 80 g/L albumen protein as lubricant. Additionally, the research explores the feasibility of surface modification by sequential ion implantation with argon and oxygen to enhance the wear characteristics of the Ni-Ti alloy. Each of these implantations was performed to a dose of 3 x 10(17) atom/cm(2) and an energy of 50 kV, using the plasma source ion implantation process. Improvements in wear resistance were observed for the austenitic samples implanted with argon and oxygen. Ion implantation with argon also reduced the surface Ni content with respect to Ti due to differential sputtering rates of the two elements, an effect that points toward improved biocompatibility.

  20. 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.

  1. 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

  2. Incidental gall bladder carcinoma in laparoscopic cholecystectomy: a report of 6 cases and a review of the literature.

    PubMed

    Sujata, Jetley; S, Rana; Sabina, Khan; Mj, Hassan; Jairajpuri, Zeeba Shamim

    2013-01-01

    Gall bladder carcinoma accounts for 98% of all the gall bladder malignancies and it is the sixth most common malignancy of the gastrointestinal tract worldwide. The incidence of incidental gall bladder carcinoma which is diagnosed during or after a laparoscopic cholecystectomy is reported to be around 0.19-3.3% in the literature. This study was aimed at detecting the incidence of gall bladder carcinomas which were diagnosed incidentally during or after laparoscopic cholecystectomies which were done for gall stone disease and cholecystitis. We analyzed the medical records of patients with symptomatic gallstone disease and acute or chronic cholecystitis, who underwent laparoscopic cholecystectomies at the Hakeem Abdul Hameed Centenary Hospital during the period from January 2007 to June 2012. A total of 622 laparoscopic cholecystectomies were performed at our institute during the study period of five and a half years. In 6 (0.96%) cases, incidental carcinomas of the gallbladder were discovered. A laparoscopic cholecystectomy which is performed for benign gall bladder disease rarely results in a diagnosis of unexpected gallbladder cancer. The microscopic examination of the specimens, with special attention to the depth of invasion, range of the mucosal spread and the lymphovascular involvement, is critical in diagnosing the incidental malignancies as well as for the subsequent management of the cases.

  3. Microstructural studies of wear mechanisms in cast aluminum alloys

    NASA Astrophysics Data System (ADS)

    Elmadagli, Mustafa

    2005-07-01

    The microstructural basis of wear and surface degradation mechanisms in Al-Si alloys has been investigated in order to improve the current understanding of the requirements for wear resistant aluminum alloy design. The wear behaviour of three commercial alloys namely: a sand cast A390 (Al-18.4%Si), a spray formed Al-25%Si, and a die cast 383 (Al-9.5%Si) have been investigated. Dry sliding wear tests were performed using a block on ring type tribometer under controlled environments. The experiments were performed in a load range between 0.2 N and 300 N at a constant speed of 1 m/s. The testing environments were a dry air (5% RH), a humid air (95% RH), and an argon atmosphere. In dry air (5% RH), two main wear regimes namely, mild wear (MW), and severe wear (SW) were identified. The (MW) regime consisted of two sub-regimes: first and second regimes of mild wear, (MW-1) and (MW-2). The mild wear was controlled by the formation and destruction (spallation) of hardened tribolayers composed of Fe, Al, Si, and O which gave rise to steady state wear rates in both sub-regimes. The transition to second sub-regime was attributed to the destabilization and partial removal of the tribolayers on the contact surfaces. Severe wear occurred at loads exceeding 150 N irrespective of the alloy when the contact surface temperature reached a critical value (210-240°C). The wear rates (W) in each sub-regime of the MW obeyed the relation, W=CLn, where C and n were the wear coefficient and the wear exponent, respectively. The wear exponents, n, were similar in each of the sub-regimes for all three alloys, indicating that the same mechanisms controlled the wear rates. However, the wear coefficients, C, and the transition loads to the second sub-regime were considerably different for each alloy. A method of analyzing the wear coefficients and the transition loads of the alloys, based on pair-wise comparison between them, was developed. This method demonstrated that small equiaxed silicon

  4. Effect of thermal treatments on the wear behaviour of duplex stainless steels

    NASA Astrophysics Data System (ADS)

    Fargas, G.; Mestra, A.; Anglada, M.; Mateo, A.

    2009-09-01

    Duplex stainless steel (DSS) is a family of steels characterized by two-phase microstructure with similar percentages of ferrite (α) and austenite (γ).Their attractive combination of mechanical properties and corrosion resistance has increased its use in last decades in the marine and petrochemical industries. Nevertheless, an inappropriate heat treatment can induce the precipitation of secondary phases which affect directly their mechanical properties and corrosion resistance. There are few works dealing with the influence of heat treatments on wear behaviour of these steels in the literature. For instances, this paper aims to determine wear kinetic and sliding wear volume developed as a function of heat treatment conditions. Therefore, the samples were heat treated from 850 °C to 975 °C before sliding wear tests. These wear tests were carried out using ball on disk technique at constant sliding velocity and different sliding distances. Two methodologies were used to calculate the wear volume: weight loss and area measurement using a simplified contact model. Microstructural observations showed the presence of sigma phase for all studied conditions. The formation kinetics of this phase is faster at 875 °C and decrease at higher temperatures. Results related to wear showed that the hardness introduced due to the presence of sigma phase plays an important role on wear behaviour for this steel. It was observed also that wear rates decreased when increasing the percentage of sigma phase on the microstructure.

  5. Infection, Reproduction Potential, and Root Galling by Root-knot Nematode Species and Concomitant Populations on Peanut and Tobacco

    PubMed Central

    Hirunsalee, Anan; Barker, K. R.; Beute, M. K.

    1995-01-01

    Single populations of Meloidogyne arenaria races 1 (MA1) and 2 (MA2) and M. hapla (MH), and mixed populations of MA1 + MA2 and MA1 + MH with four inoculum levels of eggs were tested on peanut cv. 'Florigiant' and M. incognita-resistant tobacco cv. 'McNair 373' in a greenhouse experiment. Root infection, female development, and reproduction of MA2 on peanut and MA1 on resistant tobacco were limited at 2 and 6 weeks. MA1, MH, and MA1 + MH on peanut had similar root infection (total parasitic forms per root unit) at both 2 and 6 weeks, and similar female development and reproduction potentials at 6 weeks. MA2 tended to depress root infection, female development, and reproduction of MA1 on peanut. MH had little effect on MA1 on this crop. On tobacco, MA2 population had greater incidence of root infection than did MH at 2 weeks. The two nematode species had similar development in roots at 6 weeks. All of these processes were restricted when either MA2 or MH was present together with MA1. As initial inoculum level of parasitically fit populations increased, relative infection ratio on both peanut and tobacco, and reproduction factor on peanut decreased. Populations that had high infection incidence and reproduction rates induced greater root galling than did other populations. Root galling was suppressed in the presence of antagonistic response between nematode populations. PMID:19277277

  6. Nano- and Macro-wear of Bio-carbo-nitrided AISI 8620 Steel Surfaces

    NASA Astrophysics Data System (ADS)

    Arthur, Emmanuel Kwesi; Ampaw, Edward; Zebaze Kana, M. G.; Adetunji, A. R.; Olusunle, S. O. O.; Adewoye, O. O.; Soboyejo, W. O.

    2015-12-01

    This paper presents the results of an experimental study of nano- and macro-scale wear in a carbo-nitrided AISI 8620 steel. Carbo-nitriding is carried out using a novel method that involves the use of dried, cyanide-containing cassava leaves, as sources of carbon and nitrogen. These are used in a pack cementation that is used to diffuse carbon and nitrogen into case layers at intermediate temperatures [673.15 K, 723.15 K, 773.15 K, and 823.15 K (400 °C, 450 °C, 500 °C, and 550 °C)]. Nano- and macro-scale wear properties are studied in the case-hardened surfaces, using a combination of nano-scratch and pin-on-disk experiments. The measured wear volumes (at both nano- and macro-length scales) are shown to increase with decreasing pack cyaniding temperature. The nano- and macro-wear resistances are also shown to be enhanced by the in situ diffusion of carbon and nitrogen from cyanide-containing bio-processed waste. The underlying wear mechanisms are also elucidated via atomic force microscopy and scanning electron microscopy observations of the wear tracks. The implications of the results are discussed for the design of hardened carbo-nitrided steel surfaces with improved wear resistance.

  7. 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.

  8. Quantitative differences detected in the histology of galls induced by the same aphid species in different varieties of the same host.

    PubMed

    Martinez, J-J I; Moreno-González, V; Jonas-Levi, A; Álvarez, R

    2018-05-01

    Plant galls are abnormal growths caused by an inducer that determines their morphology and anatomy. We qualitatively and quantitatively compared the histological anatomy of five aphid species (Paracletus cimiciformis, Forda marginata, Forda formicaria, Baizongia pistaciae and Geoica wertheimae) that induce galls in Pistacia terebinthus shrubs growing in Israel. We also quantitatively compared these galls to those that the aphids create on the same host in Spain. Histological study was conducted following methods described previously by the authors. Quantitative differences among the galls were found in five of 12 common anatomical traits: gall thickness, stomatal number in the epidermis-air, size of vascular bundles, distance of phloem ducts from the lumen and number of intraphloematic schizogenous ducts. Other structures were particular to one or some species: number of cracks in the epidermis-lumen, a sclereid layer, trichomes and microcrystal inclusions. Fisher's tests of combined probabilities showed that the galls induced in Israel were statistically different from those in Spain. In particular, the number of intraphloematic schizogenous ducts was higher in the galls induced in P. terebinthus in Israel. Such differences were also found in other traits related to defence of the gall inhabitant. In conclusion, while the gall shape and size are determined mainly by the cecidogenic insect, it seems that the host plant also plays an important role in determining the number/size of quantitative traits, in this case mainly protective structures. © 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

  9. Effect of mechanical vibrations on the wear behavior of AZ91 Mg alloy

    NASA Astrophysics Data System (ADS)

    Chaturvedi, V.; Pandel, U.; Sharma, A.

    2018-02-01

    AZ91 Mg alloy is the most promising alloy used for structural applications. The vibration induced methods are effective and economic viable in term of mechanical properties. Sliding wear tests were performed on AZ91 Mg alloy using a pin-on- disc configuration. Wear rates were measured at 5 N and 10N at a sliding velocity of 1m/s for varied frequency within the range of 5- 25Hz and a constant amplitude of 2mm. Microstructures of worn surfaces and wear debris were characterized by field emission scanning electron microscopy (FESEM). It is observed that wear resistance of vibrated AZ91 alloy at 15Hz frequency ad 2mm amplitude was superior than cast AZ91 Mg alloy. Finer grain size and equiaxed grain shape both are important parameters for better wear resistance in vibrated AZ91 Mg alloys. FESEM analysis revealed that wear is considerably affected due to frictional heat generated by the relative motion between AZ91 Mg alloy and EN31 steel surface. No single mechanism was responsible for material loss.

  10. In vitro wear rates of materials under different loads and varying pH.

    PubMed

    Shabanian, Mitra; Richards, Lindsay C

    2002-06-01

    Despite the need for information about the wear characteristics of restorative materials, there have been few systemic studies of the factors that influence the rate of material wear. This study compared the wear rates of enamel and 3 tooth-colored restorative materials under different loads (0, 3.2, 6.7, and 9.95 kg) and pH levels (1.2, 3.3, and 7.0). An electromechanical tooth wear machine was used so that standard restorations representing 3 materials could be worn by opposing enamel under controlled conditions. The wear rates of enamel, composite (Z100), a conventional glass ionomer cement (Fuji IX), and a resin-modified glass ionomer cement (Fuji II LC) were compared at a range of loads (0 to 9.95 kg) and pH levels (1.2 to 7.0) and also at different sites across each restoration. Ten specimens were randomly assigned to each experimental group. Wear assessment was performed with a modified light microscope to quantify the height changes at defined points across wear facets. Four-way analysis of variance was used to compare wear rates among materials, pH levels, loads, and sites. Post-hoc t tests identified significant differences between specific pairs of experimental conditions (P<.05). The wear rates of enamel and the other test materials varied significantly with pH (P<.0001), load (P<.0001), and type of material (P<.0001). Enamel wear was influenced most by varied pH, whereas the composite was least affected by acid. The conventional glass ionomer cement was more susceptible than the composite to the effects of varied pH; the acid susceptibility of the resin-modified glass ionomer cement was generally between that of the composite and conventional glass ionomer cement. Enamel and the conventional glass ionomer cement were affected similarly by load. The composite was more resistant than the conventional glass ionomer cement to wear at higher loads; the resin-modified glass ionomer cement exhibited intermediate load resistance. Within the limitations of this

  11. Two-body and three-body wear of glass ionomer cements.

    PubMed

    Kunzelmann, K H; Bürkle, V; Bauer, C

    2003-11-01

    Glass ionomer cements (GIC) have been modified in an attempt to improve their mechanical properties. The objective of the present paper was to compare the two-body and three-body wear of four modified GIC. The tested materials were Fuji IX (GC Corporation), Hi-Fi (Shofu) and Ketac Molar Aplicap (3M/ESPE). The cermet cement Ketac Silver Maxicap (3M/ESPE) was used as reference material. Two-body wear tests were carried out in the computer controlled 'artificial mouth' of the Munich Dental School, three-body wear was tested with the ACTA wear machine. The resulting average two-body wear rates (in microm) were: Fuji IX 327 (SD +/- 82) < Ketac Molar 379 (SD +/- 94) < Hi-Fi 376 (SD +/- 90) < Ketac silver 449 (SD +/- 127). The differences between the materials were significant (P < 0.05, ANOVA, modified LSD-test) with the exception of Ketac Molar and Hi-Fi. The average three-body wear rates (in microm) were: Hi-Fi 30 (SD +/- 10) < Ketac Molar +/- 42 (SD +/- 12) < Fuji IX 49 (SD +/- 14) < Ketac silver 73 (SD +/- 23). The difference between Ketac silver and the three other materials was significant (P < 0.05, ANOVA, modified LSD-test). No significant difference was calculated between Hi-Fi, Ketac Molar and Fuji IX. As Ketac Molar, Hi-Fi and Fuji IX show better wear resistance compared to Ketac silver both in occlusal-contact and contact-free areas, it may be assumed that the wear resistance of a glass ionomer cement may be improved more by changing the powder: liquid ratio than by incorporating silver particles into the glass powder.

  12. The interrelationships of three gall makers and their natural enemies, on hackberry (Celtis Occidentalis L.)

    Treesearch

    John C. Moser

    1965-01-01

    This bulletin describes three hackberry galls, the insects which make them, and 19 of their natural enemies in the Cayuga Valley near Ithaca, N.Y. Two galls were caused by psyllids and the third by a cecidomyiid. The taxonomy, biology, morphology, and distribution of the species are discussed. Fourteen natural enemies attacked the psyllid...

  13. Applicability of out-of-pile fretting wear tests to in-reactor fretting wear-induced failure time prediction

    NASA Astrophysics Data System (ADS)

    Kim, Kyu-Tae

    2013-02-01

    In order to investigate whether or not the grid-to-rod fretting wear-induced fuel failure will occur for newly developed spacer grid spring designs for the fuel lifetime, out-of-pile fretting wear tests with one or two fuel assemblies are to be performed. In this study, the out-of-pile fretting wear tests were performed in order to compare the potential for wear-induced fuel failure in two newly-developed, Korean PWR spacer grid designs. Lasting 20 days, the tests simulated maximum grid-to-rod gap conditions and the worst flow induced vibration effects that might take place over the fuel life time. The fuel rod perforation times calculated from the out-of-pile tests are greater than 1933 days for 2 μm oxidized fuel rods with a 100 μm grid-to-rod gap, whereas those estimated from in-reactor fretting wear failure database may be about in the range of between 60 and 100 days. This large discrepancy in fuel rod perforation may occur due to irradiation-induced cladding oxide microstructure changes on the one hand and a temperature gradient-induced hydrogen content profile across the cladding metal region on the other hand, which may accelerate brittleness in the grid-contacting cladding oxide and metal regions during the reactor operation. A three-phase grid-to-rod fretting wear model is proposed to simulate in-reactor fretting wear progress into the cladding, considering the microstructure changes of the cladding oxide and the hydrogen content profile across the cladding metal region combined with the temperature gradient. The out-of-pile tests cannot be directly applicable to the prediction of in-reactor fretting wear-induced cladding perforations but they can be used only for evaluating a relative wear resistance of one grid design against the other grid design.

  14. The ecology and evolution of gall-forming insects.

    Treesearch

    Peter W. Price; William J. Mattson; Yuri N. Baranchikov

    1994-01-01

    This international proceedings focuses on the biology, ecology, and evolution of gall-forming insects and their uniquely specialized relationships with their host plants. The individual contributions range in scope from detailed descriptive to profoundly theoretical, synthetic studies. One underlying theme of the proceedings is the important contribution of knowledge...

  15. Science Galls Me: What Is a Niche Anyway?

    ERIC Educational Resources Information Center

    Halverson, Kristy Lynn; Lankford, Deanna Marie

    2009-01-01

    The authors have developed a lesson to investigate basic principles of ecology, more specifically niche partitioning, while using a jigsaw activity that explores galling insects' interactions with goldenrods. Not only does this lesson capture secondary students' interest and keeps them engaged in hands-on activities, the content addresses two…

  16. Incidental Gall Bladder Carcinoma in Laparoscopic Cholecystectomy: A Report of 6 Cases and a Review of the Literature

    PubMed Central

    Sujata, Jetley; S, Rana; Sabina, Khan; MJ, Hassan; Jairajpuri, Zeeba Shamim

    2013-01-01

    Background: Gall bladder carcinoma accounts for 98% of all the gall bladder malignancies and it is the sixth most common malignancy of the gastrointestinal tract worldwide. The incidence of incidental gall bladder carcinoma which is diagnosed during or after a laparoscopic cholecystectomy is reported to be around 0.19-3.3% in the literature. Aim: This study was aimed at detecting the incidence of gall bladder carcinomas which were diagnosed incidentally during or after laparoscopic cholecystectomies which were done for gall stone disease and cholecystitis. Materials and Methods: We analyzed the medical records of patients with symptomatic gallstone disease and acute or chronic cholecystitis, who underwent laparoscopic cholecystectomies at the Hakeem Abdul Hameed Centenary Hospital during the period from January 2007 to June 2012. Results: A total of 622 laparoscopic cholecystectomies were performed at our institute during the study period of five and a half years. In 6 (0.96%) cases, incidental carcinomas of the gallbladder were discovered. Conclusion: A laparoscopic cholecystectomy which is performed for benign gall bladder disease rarely results in a diagnosis of unexpected gallbladder cancer. The microscopic examination of the specimens, with special attention to the depth of invasion, range of the mucosal spread and the lymphovascular involvement, is critical in diagnosing the incidental malignancies as well as for the subsequent management of the cases. PMID:23449518

  17. Coatings for wear and lubrication

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1978-01-01

    Recent advances in the tribological uses of rf-sputtered and ion plated films of solid film lubricants (laminar solids, soft metals, organic polymers) and wear resistant refractory compounds (carbides, nitrides, silicides) are reviewed. The sputtering and ion plating potentials and the corresponding coatings formed were evaluated relative to the friction coefficient, wear endurance life and mechanical properties. The tribological and mechanical properties for each kind of film are discussed in terms of film adherence, coherence, density, grain size, morphology, internal stresses, thickness, and substrate conditions such as temperature, topography, chemistry and dc-biasing. The ion plated metallic films in addition to improved tribological properties also have better mechanical properties such as tensile strength and fatigue life.

  18. Genipin crosslinking decreases the mechanical wear and biochemical degradation of impacted cartilage in vitro.

    PubMed

    Bonitsky, Craig M; McGann, Megan E; Selep, Michael J; Ovaert, Timothy C; Trippel, Stephen B; Wagner, Diane R

    2017-03-01

    High energy trauma to cartilage causes surface fissures and microstructural damage, but the degree to which this damage renders the tissue more susceptible to wear and contributes to the progression of post-traumatic osteoarthritis (PTOA) is unknown. Additionally, no treatments are currently available to strengthen cartilage after joint trauma and to protect the tissue from subsequent degradation and wear. The purposes of this study were to investigate the role of mechanical damage in the degradation and wear of cartilage, to evaluate the effects of impact and subsequent genipin crosslinking on the changes in the viscoelastic parameters of articular cartilage, and to test the hypothesis that genipin crosslinking is an effective treatment to enhance the resistance to biochemical degradation and mechanical wear. Results demonstrate that cartilage stiffness decreases after impact loading, likely due to the formation of fissures and microarchitectural damage, and is partially or fully restored by crosslinking. The wear resistance of impacted articular cartilage was diminished compared to undamaged cartilage, suggesting that mechanical damage that is directly induced by the impact may contribute to the progression of PTOA. However, the decrease in wear resistance was completely reversed by the crosslinking treatments. Additionally, the crosslinking treatments improved the resistance to collagenase digestion at the impact-damaged articular surface. These results highlight the potential therapeutic value of collagen crosslinking via genipin in the prevention of cartilage degeneration after traumatic injury. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:558-565, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  19. 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.

  20. Corrosive sliding wear behavior of laser clad Mo 2Ni 3Si/NiSi intermetallic coating

    NASA Astrophysics Data System (ADS)

    Lu, X. D.; Wang, H. M.

    2005-05-01

    Many ternary metal silicides such as W 2Ni 3Si, Ti 2Ni 3Si and Mo 2Ni 3Si with the topologically closed-packed (TCP) hP12 MgZn 2 type Laves phase crystal structure are expected to have outstanding wear and corrosion resistance due to their inherent high hardness and sluggish temperature dependence and strong atomic bonds. In this paper, Mo 2Ni 3Si/NiSi intermetallic coating was fabricated on substrate of an austenitic stainless steel AISI321 by laser cladding using Ni-Mo-Si elemental alloy powders. Microstructure of the coating was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS). Wear resistance of the coating is evaluated under corrosive sliding wear test condition. Influence of corrosion solutions on the wear resistance of the coating was studied and the wear mechanism was discussed based on observations of worn surface morphology. Results showed that the laser clad Mo 2Ni 3Si/NiSi composite coating have a fine microstructure of Mo 2Ni 3Si primary dendrites and the interdendritic Mo 2Ni 3Si/NiSi eutectics. The coating has excellent corrosive wear resistance compared with austenitic stainless steel AISI321 under acid, alkaline and saline corrosive environments.

  1. 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.

  2. Wear evaluation of flank in burins of high speed steel modified with titanium ions

    NASA Astrophysics Data System (ADS)

    E Caballero, J.; V-Niño, E. D.

    2017-12-01

    This report shows the results obtained researching the flank wearing resistance performed by the high-speed steel (HSS) burins without any surface treatment (reference substrate) and others with surface treatment based on Titanium ions. The flank wearing was carried out by means of an industrial process by chip removal with repetitive tests of dry finished turning of AISI/SAE 1045 steel bars. The useful service life of the burins was evaluated according to ISO 3685:1993, and it was found that the burins treated with Titanium ions showed an increase in the flank wearing resistance with respect to the ones used as reference.

  3. Cytological cycles and fates in Psidium myrtoides are altered towards new cell metabolism and functionalities by the galling activity of Nothotrioza myrtoidis.

    PubMed

    Carneiro, R G S; Isaias, R M S

    2015-03-01

    The morphogenesis of galls occurs by the redifferentiation of cells that assume new functions in the modified host plant organs. The redifferentiated cells in the galls of Nothotrioza myrtoidis on Psidium myrtoides have low complexity metabolism and are photosynthesis-deficient. These galls were studied in search for evidences of the establishment of new cell cycles and fates and cytological gradients that corroborate their metabolic profile. Young and mature leaves of P. myrtoides and leaf galls induced by N. myrtoidis at different developmental stages were collected along 24 months and analyzed under light and transmission electron microscopy. The leaves of P. myrtoides are long-lasting and did not senesce within the analyzed period, while the galls have a shorter cycle, and senesce within 1 year. A homogenous parenchyma is established by a "standby-redifferentiation" of the chlorophyllous tissues, and sclerenchyma cells redifferentiate from parenchyma cells in the outer cortex of the mature galls. The lack of organelles, the underdeveloped lamellation of chloroplasts, and the occurrence of few plastoglobules are related to the photosynthetic deficiency of the galls. No cytological gradients were observed, but the organelle-rich cells of the vascular and perivascular parenchymas are similar to those of the nutritive tissues of galls induced by other insect taxa. These cells nearest to the feeding sites of N. myrtoidis present higher metabolism and well-developed apparatus for the prevention of oxidative stress. The features herein described corroborate the low metabolic profile of the galls as the cell cycles and fates of P. myrtoides are manipulated for completely new functionalities.

  4. Wear versus Thickness and Other Features of 5-Mrad Crosslinked UHMWPE Acetabular Liners

    PubMed Central

    Shen, Fu-Wen; Lu, Zhen

    2010-01-01

    Background The low wear rates of crosslinked polyethylenes provide the potential to use larger diameters to resist dislocation. However, this requires the use of thinner liners in the acetabular component, with concern that higher contact stresses will increase wear, offsetting the benefits of the crosslinking. Questions/purposes We asked the following questions: Is the wear of conventional and crosslinked polyethylene liners affected by ball diameter, rigidity of backing, and liner thickness? Are the stresses in the liner affected by thickness? Methods Wear rates were measured in a hip simulator and stresses were calculated using finite element modeling. Results Without crosslinking, the wear rate was 4% to 10% greater with a 36-mm diameter than a 28-mm diameter. With crosslinking, wear was 9% lower with a 36-mm diameter without metal backing and 4% greater with metal backing. Reducing the thickness from 6 mm to 3 mm increased the contact stress by 46%, but the wear rate decreased by 19%. Conclusions The reduction in wear with 5 Mrad of crosslinking was not offset by increasing the diameter from 28 mm to 36 mm or by using a liner as thin as 3 mm. Clinical Relevance The results indicate, for a properly positioned 5-Mrad crosslinked acetabular component and within the range of dimensions evaluated, neither wear nor stresses in the polyethylene are limiting factors in the use of larger-diameter, thinner cups to resist dislocation. PMID:20848244

  5. Mechanical properties and three-body wear of dental restoratives and their comparative flowable materials.

    PubMed

    Schultz, Sabine; Rosentritt, Martin; Behr, Michael; Handel, Gerhard

    2010-01-01

    To compare wear performance and resistance to crack propagation (K1C) of commercial restorative materials and their flowable variations. A potential correlation between three-body wear and fracture toughness, modulus of elasticity, fracture work, Vickers hardness, and filler content was investigated. Seven restoratives (five composites, one ormocer, and one compomer) and their corresponding flowable materials were used to determine and compare the three-body wear with a bolus of millet-seed shells and rice food (Willytec). The wear characteristics were measured by profilometry after 50,000, 100,000, 150,000, and 200,000 loading cycles. The fracture toughness value, K1C (MPam1/2), for each single-edged notched specimen was measured in a three-point bending test (universal testing machine 1446, Zwick). Fracture work and modulus of elasticity were calculated from the load curves. Vickers hardness was measured (HV hardness tester, Zwick) according to DIN 50133. The veneering composite Sinfony (3M ESPE) was used as a reference material. Heavily filled composites experienced less wear than their flowable variations. The nanofiller composites revealed better wear results than hybrid composites, compomers, and ormocers. After 200,000 load cycles, the lowest wear rates were detected for Grandio (14 microm; Voco), and the highest mean values were found for Dyract AP (104 microm; Dentsply DeTrey). The values for fracture toughness (K1C) ranged from 0.82 to 3.64 MPam1/2. Highest K1C data was exhibited by the nanocomposite Nanopaq (Schutz Dental). All tested restorative materials exhibited higher fracture toughness than their low-viscosity variations. The wear resistance of the newer generation composites with incorporated nanofiller or microfiller particles increased to a high extent. Flowables show less resistance against wear and crack propagation because of their lower filler content. The reduced mechanical properties limit their use as a restorative to small noncontact

  6. Wear and Friction Behavior of Metal Impregnated Microporous Carbon Composites

    NASA Technical Reports Server (NTRS)

    Goller, Gultekin; Koty, D. P.; Tewari, S. N.; Singh, M.; Tekin, A.

    1996-01-01

    Metal-matrix composites have been prepared by pressure-infiltration casting of copper-base alloy melts into microporous carbon preforms. The carbon preforms contained varying proportions of amorphous carbon and graphite. Load dependence of the wear and friction behavior of the composite pins has been examined under ambient conditions against cast-iron plates, using a pin-on-plate reciprocating wear tester. The wear resistance of the composite is significantly improved, as compared with the base alloy. Contrary to the normally expected behavior, the addition of graphite to the amorphous carbon does not reduce the friction coefficient, especially at high loads. The wear and friction behavior of the composites is very sensitive to the size and distribution of the microstructural constituents.

  7. Skid resistance performance of asphalt wearing courses with electric arc furnace slag aggregates.

    PubMed

    Kehagia, Fotini

    2009-05-01

    Metallurgical slags are by-products of the iron and steel industry and are subdivided into blast furnace slag and steel slag according to the different steel-producing processes. In Greece, slags are mostly produced from steelmaking using the electric arc furnace process, and subsequently are either disposed in a random way or utilized by the cement industry. Steel slag has been recently used, worldwide, as hard aggregates in wearing courses in order to improve the skidding resistance of asphalt pavements. At the Highway Laboratory, Department of Civil Engineering of Aristotle University of Thessaloniki research has been carried out in the field of steel slags, and especially in electric arc furnace (EAF) slag, to evaluate their possible use in highway engineering. In this paper, the recent results of anti-skidding performance of steel slag aggregates in highway pavements are presented.

  8. Wear resistance and friction reduction in acrylo nitrile butadiene rubber through hybrid combination of graphite flakes and nano tungsten disulphide

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

    Agrawal, Neha, E-mail: neha87bhu@gmail.com; Indian Institute of Technology Bombay, Powai, Mumbai 400076, Maharashtra; Pandey, Akanksha

    Friction and wear have considerable role in the life span of two interacting parts. Incorporation of nanofillers in polymers/elastomers matrix causes commendable changes in its tribologicalproperties. The main purpose of this work is to reduce the coefficient of friction and wear rate of Acrylo Nitrile Butadiene rubber (NBR). To achieve such objective traditionally well knownlubricants graphite(G), tungsten disulphide (WS{sub 2}) and there hybrid combination was incorporated in NBR matrix. Effect of applied load (force) and concentration of fillers on tribological properties of NBR had been studied. The filler incorporation enhanced the hardnessby 8%, showed resistance to hydraulic oil and agingmore » effect also got improved significantly. A particular optimized concentration of NBR with hybrid combination of 2% WS{sub 2} and 4% Graphite showed minimum coefficient of friction as well as wear rate. A hypothesis could be attributed that similar lamellar structure of WS{sub 2} and Graphite along with formation of a stable nanoscale disulfide tribofilmcould result in lowering of friction. These substantially improved properties of nanoreinforced rubber materials would definitely pave promising path for plethora of potential technological applications.« less

  9. Phylogeny of Rhus gall aphids (Hemiptera:Pemphigidae) based on combined molecular analysis of nuclear EF1α and mitochondrial COII genes

    Treesearch

    Zi-xiang Yang; Xiao-ming Chen; Nathan P. Havill; Ying Feng; Hang Chen

    2010-01-01

    Rhus gall aphids (Fordinae : Melaphidini) have a disjunct distribution in East Asia and North America and have specific host plant relationships. Some of them are of economic importance and all species form sealed galls which show great variation in shape, size, structure, and galling-site. We present a phylogeny incorporating ten species and four...

  10. Microstructure and wear resistance of Al2O3-M7C3/Fe composite coatings produced by laser controlled reactive synthesis

    NASA Astrophysics Data System (ADS)

    Tan, Hui; Luo, Zhen; Li, Yang; Yan, Fuyu; Duan, Rui

    2015-05-01

    Based on the principle of thermite reaction of Al and Fe2O3 powders, the Al2O3 ceramic reinforced Fe-based composite coatings were fabricated on a steel substrate by laser controlled reactive synthesis and cladding. The effects of different additions of thermite reactants on the phase transition, microstructure evolution, microhardness and wear resistance of the composite coatings were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Vickers microhardness and block-on-ring wear test, respectively. The results show that Al2O3 ceramic and M7C3 carbide are in situ synthesized via the laser controlled reactive synthesis. The Al2O3 ceramic and M7C3 carbides prefer to distribute along the γ-Fe phase boundary continuously, which separates the γ-Fe matrix and is beneficial to the grain refinement. With the increase of thermite reactants, the amount of Al2O3 ceramic and M7C3 carbide in the composite coatings increases gradually. Moreover the cladding layer changes from dendritic structure to columnar structure and martensite structure in the heat affected zone becomes coarse. The increased thermite reactants improve the microhardness and wear resistance of the in situ composite coatings obviously and enhance the hardness of the heat affected zone, which should be ascribed to the grain refinement, ceramic and carbide precipitation and solid solution strengthening.

  11. Wear resistance of poly(2-methacryloyloxyethyl phosphorylcholine)-grafted carbon fiber reinforced poly(ether ether ketone) liners against metal and ceramic femoral heads.

    PubMed

    Yamane, Shihori; Kyomoto, Masayuki; Moro, Toru; Hashimoto, Masami; Takatori, Yoshio; Tanaka, Sakae; Ishihara, Kazuhiko

    2018-04-01

    Younger, active patients who undergo total hip arthroplasty (THA) have increasing needs for wider range of motion and improved stability of the joint. Therefore, bearing materials having not only higher wear resistance but also mechanical strength are required. Carbon fiber-reinforced poly(ether ether ketone) (CFR-PEEK) is known as a super engineering plastic that has great mechanical strength. In this study, we focused on poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC)-grafted CFR-PEEK and investigated the effects of PMPC grafting and the femoral heads materials on the wear properties of CFR-PEEK liners. Compared with untreated CFR-PEEK, the PMPC-grafted CFR-PEEK surface revealed higher wettability and lower friction properties under aqueous circumstances. In the hip simulator wear test, wear particles generated from the PMPC-grafted CFR-PEEK liners were fewer than those of the untreated CFR-PEEK liners. There were no significant differences in the size and the morphology of the wear particles between the differences of PMPC-grafting and the counter femoral heads. Zirconia-toughened alumina (ZTA) femoral heads had significantly smoother surfaces compared to cobalt-chromium-molybdenum alloy femoral heads after the hip simulator test. Thus, we conclude that the bearing combination of the PMPC-grafted CFR-PEEK liner and ZTA head is expected to be a lifelong bearing interface in THA. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1028-1037, 2018. © 2017 Wiley Periodicals, Inc.

  12. Comparative study of anti-drift nozzles' wear.

    PubMed

    Bolly, G; Huyghebaert, B; Mostade, O; Oger, R

    2002-01-01

    When spraying, the drift is a restricting factor which reduces the efficiency of pesticides treatments and increases their impact on the environment. The use of anti-drift nozzles is the most common technique to reduce the drift effect. The basic principle of all anti-drift nozzles is to produce bigger droplets (Imag DLO, 1999) being less sensitive to the wind. The increase of the droplets' size is possible whether by reducing the spraying pressure (anti-drift fan nozzle) or by injecting air in the nozzle (air injection nozzles). This study aims at comparing the performances of the main anti-drift nozzles available on the Belgian market (Teejet DG and AI, Albuz ADI and AVI, Hardi ISO LD et AI). The study made it possible to compare thirteen different nozzles' sets according to their trademark, type and material. The study is based on the analysis of macroscopic parameters (flowrate, transversal distribution and individual distribution) as well as on the analysis of microscopic parameters (spraying deposit on artificial target). The evolution of these parameters is analysed according to the nozzle's wear. The wear is carried out artificially according to the "ISO 5682-1" standard (ISO 5682-1, 1996). The results confirmed the major influence of the manufacturing material on the nozzles' wear, ceramic being the most resistant material. Macroscopic as well as microscopic parameters variated according to the utilization time without any direct correlation. Indeed, most parameters variate in an uncertain way. It was however possible to establish a correlation between the wear time and the recovering rate and flowrate parameters. The utilization length is different depending on the type of nozzle, air injection nozzles being more resistant. At last, the analysis of microscopic parameters (spraying deposit) (Degré A., 1999), shows that the number of impacts is stable depending on the wear, while the size of impacts and the recovering rate increase.

  13. Absorption of Bile Pigments by the Gall Bladder*

    PubMed Central

    Ostrow, J. Donald

    1967-01-01

    A technique is described for preparation in the guinea pig of an in situ, isolated, vascularized gall bladder that exhibits normal absorptive functions. Absorption of labeled bile pigments from the gall bladder was determined by the subsequent excretion of radioactivity in hepatic bile. Over a wide range of concentrations, unconjugated bilirubin-14C was well absorbed, whereas transfer of conjugated bilirubin proceeded slowly. Mesobilirubinogen-3H was absorbed poorly from whole bile, but was absorbed as rapidly as unconjugated bilirubin from a solution of pure conjugated bile salt. Bilirubin absorption was not impaired by iodoacetamide, 1.5 mM, or dinitrophenol, 1.0 mM, even though water transport was affected. This indicated that absorption of bilirubin was not dependent upon water transport, nor upon energy-dependent processes. The linear relationship between absorption and concentration of pigment at low concentrations in bile salt solutions suggested that pigment was transferred by passive diffusion. At higher pigment concentrations or in whole bile, this simple relationship was modified by interactions of pigment with bile salts and other constituents of bile. These interactions did not necessarily involve binding of bilirubin in micelles. The slow absorption of the more polar conjugates and photo-oxidative derivatives of bilirubin suggested that bilirubin was absorbed principally by nonionic, and partially, by ionic diffusion. Concentrations of pure conjugated bile salts above 3.5 mM were found to be injurious to the gall bladder mucosa. This mucosal injury did not affect the kinetics of bilirubin absorption. During in vitro incubation of bile at 37°C, decay of bilirubin and hydrolysis of the conjugate proceeded as first-order reactions. The effects of these processes on the kinetics of bilirubin absorption, and their possible role in the formation of “white bile” and in the demonstrated appearance of unconjugated bilirubin in hepatic bile, are discussed

  14. Potential countersample materials for in vitro simulation wear testing.

    PubMed

    Shortall, Adrian C; Hu, Xiao Q; Marquis, Peter M

    2002-05-01

    Any laboratory investigation of the wear resistance of dental materials needs to consider oral conditions so that in vitro wear results can be correlated with in vivo findings. The choice of the countersample is a critical factor in establishing the pattern of tribological wear and in achieving an efficient in vitro wear testing system. This research investigated the wear behavior and surface characteristics associated with three candidate countersample materials used for in vitro wear testing in order to identify a possible suitable substitute for human dental enamel. Three candidate materials, stainless steel, steatite and dental porcelain were evaluated and compared to human enamel. A variety of factors including hardness, wear surface evolution and frictional coefficients were considered, relative to the tribology of the in vivo situation. The results suggested that the dental porcelain investigated bore the closest similarity to human enamel of the materials investigated. Assessment of potential countersample materials should be based on the essential tribological simulation supported by investigations of mechanical, chemical and structural properties. The selected dental porcelain had the best simulating ability among the three selected countersample materials and this class of material may be considered as a possible countersample material for in vitro wear test purposes. Further studies are required, employing a wider range of dental ceramics, in order to optimise the choice of countersample material for standardized in vitro wear testing.

  15. FARMACOGNOSTICAL STUDIES ON THE SOUTH INDIAN MARKET SAMPLE OF KARKATASRINGI (KADUKKAIPOO) – TERMINALIA CHEBUL (GAERTN. LEAF GALL)

    PubMed Central

    Santha, T. R.; Shetty, J. K. P.; Yoganarasimhan, S. N.; Sudha, R.

    1991-01-01

    Pharmacognostical studies on the South Indian market sample of Karkatasringi (Terminalia chebula leaf galls) were carried out along with comparative studies on Pistacia integerima which is the accepted source of Karkatasringi. The galls of T. chebula are also known as Kadukkai Poo in Siddha system. PMID:22556552

  16. Influence of heat treatment on structural, mechanical and wear properties of crosslinked UHMWPE.

    PubMed

    Chiesa, R; Moscatelli, M; Giordano, C; Siccardi, F; Cigada, A

    2004-01-01

    New crosslinked ultra high molecular weight polyethylenes (UHMWPEs) have recently been developed, characterized and introduced in clinical applications. UHMWPE cross-linking treatments are very promising for reducing osteolysis induced by wear debris. The irradiation type, gamma or beta, the dosage and the thermal treatment performed during or following the irradiation process are all factors affecting polyethylene wear resistance. Thermal stabilization treatments performed after or during the irradiation process at a temperature above melting point (i.e. >130 degrees C) have been proven to effectively remove the free radicals generated during irradiation from UHMWPE, but their effect on the mechanical properties of UHMWPE are not completely clear. In addition to wear rate reduction, maintaining good mechanical properties is fundamental aspect in designing the new generation of crosslinked UHMWPE for artificial load bearing materials, especially considering the application in total knee replacements. In this study, we investigated the influence of different stabilization treatments, performed after gamma irradiation, on structural, wear and mechanical properties of UHMWPE. We performed four different stabilization treatments, with different temperatures and cooling rates, on 100 kGy gamma irradiated UHMWPE. Structural properties of UHMWPE were assessed by differential scanning calorimetry (DSC). To assess the mechanical performance of the materials, uni-axial tensile tests were performed according to the ASTM D638 standard, bi-axial tension performance was evaluated by small punch tests (ASTM F2183-02), toughness resistance was evaluated by the Izod method (ASTM F648), and cold flow resistance was analysed by a dynamic compressive test. Evaluation of wear resistance was by a multidirectional pin-on-disk screening machine. Materials considered were in "aged" and "non-aged" conditions. Results confirmed that cross-linking greatly enhances UHMWPE wear resistance, but

  17. Host-driven diversification of gall-inducing Acacia thrips and the aridification of Australia

    PubMed Central

    McLeish, Michael J; Chapman, Thomas W; Schwarz, Michael P

    2007-01-01

    Background Insects that feed on plants contribute greatly to the generation of biodiversity. Hypotheses explaining rate increases in phytophagous insect diversification and mechanisms driving speciation in such specialists remain vexing despite considerable attention. The proliferation of plant-feeding insects and their hosts are expected to broadly parallel one another where climate change over geological timescales imposes consequences for the diversification of flora and fauna via habitat modification. This work uses a phylogenetic approach to investigate the premise that the aridification of Australia, and subsequent expansion and modification of arid-adapted host flora, has implications for the diversification of insects that specialise on them. Results Likelihood ratio tests indicated the possibility of hard molecular polytomies within two co-radiating gall-inducing species complexes specialising on the same set of host species. Significant tree asymmetry is indicated at a branch adjacent to an inferred transition to a Plurinerves ancestral host species. Lineage by time diversification plots indicate gall-thrips that specialise on Plurinerves hosts differentially experienced an explosive period of speciation contemporaneous with climatic cycling during the Quaternary period. Chronological analyses indicated that the approximate age of origin of gall-inducing thrips on Acacia might be as recent as 10 million years ago during the Miocene, as truly arid landscapes first developed in Australia. Conclusion Host-plant diversification and spatial heterogeneity of hosts have increased the potential for specialisation, resource partitioning, and unoccupied ecological niche availability for gall-thrips on Australian Acacia. PMID:17257412

  18. 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.

  19. Characterization of the bile and gall bladder microbiota of healthy pigs.

    PubMed

    Jiménez, Esther; Sánchez, Borja; Farina, Annarita; Margolles, Abelardo; Rodríguez, Juan M

    2014-12-01

    Bile is a biological fluid synthesized in the liver, stored and concentrated in the gall bladder (interdigestive), and released into the duodenum after food intake. The microbial populations of different parts of mammal's gastrointestinal tract (stomach, small and large intestine) have been extensively studied; however, the characterization of bile microbiota had not been tackled until now. We have studied, by culture-dependent techniques and a 16S rRNA gene-based analysis, the microbiota present in the bile, gall bladder mucus, and biopsies of healthy sows. Also, we have identified the most abundant bacterial proteins in the bile samples. Our data show that the gall bladder ecosystem is mainly populated by members of the phyla Proteobacteria, Firmicutes, and Bacteroidetes. Furthermore, fluorescent in situ hybridization (FISH) and transmission electron microscopy (TEM) allowed us to visualize the presence of individual bacteria of different morphological types, in close association with either the epithelium or the erythrocytes, or inside the epithelial cells. Our work has generated new knowledge of bile microbial profiles and functions and might provide the basis for future studies on the relationship between bile microbiota, gut microbiota, and health. © 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  20. Wear rates of artificial denture teeth opposed by natural dentition.

    PubMed

    Douglas, W H; Delong, R; Pintado, M R; Latta, M A

    1993-01-01

    The wear rate of polymeric or composite-based artificial denture teeth on fixed, removable and implant prostheses is important in the maintenance of cuspal form, masticatory efficiency and occlusal stability. A servo-hydraulic based artificial mouth in which an occlusion was established between artificial denture teeth, and the palatal cusp of a human maxillary third molar was established and used to assess the wear resistance of 5 artificial denture tooth materials. Volumetric wear was determined for Dentsply Trublend SLM, Dentsply IPN, Vita Vitapan, Ivoclar Orthotyp and Ivoclar Orthosit denture teeth. Scanning electron microscopy was also done to assess the textural character of the wear facets of each denture tooth sample. The lowest volume loss was observed for Trublend SLM followed by IPN, Orthotyp, Vitapan and Orthosit. Textural assessment of the materials was consistent with the objective wear data.

  1. The Wear Behavior of Textured Steel Sliding against Polymers

    PubMed Central

    Wang, Meiling; Zhang, Changtao; Wang, Xiaolei

    2017-01-01

    Artificially fabricated surface textures can significantly improve the friction and wear resistance of a tribological contact. Recently, this surface texturing technique has been applied to polymer materials to improve their tribological performance. However, the wear behavior of textured tribo-pairs made of steel and polymer materials has been less thoroughly investigated and is not well understood; thus, it needs further research. The aim of this study is to investigate the wear properties of tribological contacts made of textured stainless steel against polymer surfaces. Three polymer materials were selected in this study, namely, ultrahigh molecular weight polyethylene (UHMWPE), polyoxymethylene (POM) and (polyetheretherketone) PEEK. Wear tests were operated through a ring-on-plane mode. The results revealed that the texture features and material properties affected the wear rates and friction coefficients of the textured tribo-pairs. In general, PEEK/textured steel achieved the lowest wear rate among the three types of tribo-pairs investigated. Energy dispersive x-ray spectroscopy (EDX) analysis revealed that the elements of C and O on the contacting counterfaces varied with texture features and indicated different wear behavior. Experimental and simulated results showed differences in the stress distribution around the dimple edge, which may influence wear performance. Wear debris with different surface morphologies were found for tribo-pairs with varying texture features. This study has increased the understanding of the wear behavior of tribo-pairs between textured stainless steel and polymer materials. PMID:28772688

  2. 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.

  3. [Franz Joseph Gall and his "talking skulls" established the basis of modern brain sciences].

    PubMed

    Wolfgang, Regal; Michael, Nanut

    2008-01-01

    The anatomist and brain scientist Franz Joseph Gall (1758-1828) developed the "phrenology" in the early 19(th) century. At this time, his new teachings were more seen as a temporary fashion than science and were discredited. No more than hundred years ago, it was realised that the phrenology established the basis of modern brain sciences. By all means Gall was the first one to combine defined regions of the cerebral cortex with distinct cognitive functions.

  4. 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.

  5. Galled by the Gallbladder?: Your Tiny, Hard-Working Digestive Organ

    MedlinePlus

    ... Galled by the Gallbladder? Your Tiny, Hard-Working Digestive Organ En español Send us your comments Most ... among the most common and costly of all digestive system diseases. By some estimates, up to 20 ...

  6. Corrosion and wear behaviors of boronized AISI 316L stainless steel

    NASA Astrophysics Data System (ADS)

    Kayali, Yusuf; Büyüksaǧiş, Aysel; Yalçin, Yılmaz

    2013-09-01

    In this study, the effects of a boronizing treatment on the corrosion and wear behaviors of AISI 316L austenitic stainless steel (AISI 316L) were examined. The corrosion behavior of the boronized samples was studied via electrochemical methods in a simulation body fluid (SBF) and the wear behavior was examined using the ball-on-disk wear method. It was observed that the boride layer that formed on the AISI 316L surface had a flat and smooth morphology. Furthermore, X-ray diffraction analyses show that the boride layer contained FeB, Fe2B, CrB, Cr2B, NiB, and Ni2B phases. Boride layer thickness increased with an increasing boronizing temperature and time. The boronizing treatment also increased the surface hardness of the AISI 316L. Although there was no positive effect of the coating on the corrosion resistance in the SBF medium. Furthermore, a decrease in the friction coefficient was recorded for the boronized AISI 316L. As the boronizing temperature increased, the wear rate decreased in both dry and wet mediums. As a result, the boronizing treatment contributed positively to the wear resistance by increasing the surface hardness and by decreasing the friction coefficient of the AISI 316L.

  7. Microstructure and wear resistance of Ti-Cu-N composite coating prepared via laser cladding/laser nitriding technology on Ti-6Al-4V alloy

    NASA Astrophysics Data System (ADS)

    Yang, Yuling; Cao, Shiyin; Zhang, Shuai; Xu, Chuan; Qin, Gaowu

    2017-07-01

    Ti-Cu-N coatings with three different Cu contents on Ti-6Al-4V alloy (TC4) were obtained via laser cladding together with laser nitriding (LC/LN) technology. Phase constituents, microstructure, microhardness, and wear resistance of the coatings were investigated. The evolution of the coefficients of friction for the three coatings was measured under dry sliding conditions as a function of the revolutions until the coating failure. The results show that the coatings are mainly composed of TiN, CuTi3 and some TiO6 phases dispersed in the matrix. A good metallurgical bonding between the coating and substrate has been successfully obtained. The prepared Ti-Cu-N composite coatings almost doubly enhance the microhardness of the TC4 alloy and reduce the friction down to 1/4-1/2 of the TC4 alloy, and thus significantly improve the wear resistance. The coefficient of friction depends on the Cu content in the coating.

  8. Non-destructive study of iron gall inks in manuscripts

    NASA Astrophysics Data System (ADS)

    Duh, Jelena; Krstić, Dragica; Desnica, Vladan; Fazinić, Stjepko

    2018-02-01

    The aim of this research is to establish an effective procedure of iron gall ink characterization using complementary non-destructive methods. By this, it is possible to better understand correlation of chemical composition of the inks and the state of preservation of iron gall ink manuscripts, as well as the effects of conservation treatment performed upon them. This study was undertaken on a bound 16th century manuscript comprised of different types of paper and ink from the National and University Library in Zagreb. Analytical methods used included Particle Induced X-ray Emission (PIXE) and X-ray Fluorescence (XRF). Paper fibers were identified by optical microscopy and the degradation state, as well as ink differentiation, transit metal migrations and detection of stains, with ultraviolet (UV) and infrared (IR) photography. The techniques applied on original writing materials gave important information about paper and ink composition, its preservation state and efficiency of conservation treatment performed upon them.

  9. Wear behavior of carbide tool coated with Yttria-stabilized zirconia nano particles.

    NASA Astrophysics Data System (ADS)

    Jadhav, Pavandatta M.; Reddy, Narala Suresh Kumar

    2018-04-01

    Wear mechanism takes predominant role in reducing the tool life during machining of Titanium alloy. Challenges of wear mechanisms such as variation in chip, high pressure loads and spring back are responsible for tool wear. In addition, many tool materials are inapt for machining due to low thermal conductivity and volume specific heat of these materials results in high cutting temperature during machining. To confront this issue Electrostatic Spray Coating (ESC) coating technique is utilized to enhance the tool life to an acceptable level. The Yttria Stabilized Zirconia (YSZ) acts as a thermal barrier coating having high thermal expansion coefficient and thermal shock resistance. This investigation focuses on the influence of YSZ nanocoating on the tungsten carbide tool material and improve the machinability of Ti-6Al-4V alloy. YSZ nano powder was coated on the tungsten carbide pin by using ESC technique. The coatings have been tested for wear and friction behavior by using a pin-on-disc tribological tester. The dry sliding wear test was performed on Titanium alloy (Ti-6Al-4V) disc and YSZ coated tungsten carbide (pin) at ambient atmosphere. The performance parameters like wear rate and temperature rise were considered upon performing the dry sliding test on Ti-6Al-4V alloy disc. The performance parameters were calculated by using coefficient of friction and frictional force values which were obtained from the pin on disc test. Substantial resistance to wear was achieved by the coating.

  10. Developmental anatomy and immunocytochemistry reveal the neo-ontogenesis of the leaf tissues of Psidium myrtoides (Myrtaceae) towards the globoid galls of Nothotrioza myrtoidis (Triozidae).

    PubMed

    Carneiro, Renê G S; Oliveira, Denis C; Isaias, Rosy M S

    2014-12-01

    The temporal balance between hyperplasia and hypertrophy, and the new functions of different cell lineages led to cell transformations in a centrifugal gradient that determines the gall globoid shape. Plant galls develop by the redifferentiation of new cell types originated from those of the host plants, with new functional and structural designs related to the composition of cell walls and cell contents. Variations in cell wall composition have just started to be explored with the perspective of gall development, and are herein related to the histochemical gradients previously detected on Psidium myrtoides galls. Young and mature leaves of P. myrtoides and galls of Nothotrioza myrtoidis at different developmental stages were analysed using anatomical, cytometrical and immunocytochemical approaches. The gall parenchyma presents transformations in the size and shape of the cells in distinct tissue layers, and variations of pectin and protein domains in cell walls. The temporal balance between tissue hyperplasia and cell hypertrophy, and the new functions of different cell lineages led to cell transformations in a centrifugal gradient, which determines the globoid shape of the gall. The distribution of cell wall epitopes affected cell wall flexibility and rigidity, towards gall maturation. By senescence, it provided functional stability for the outer cortical parenchyma. The detection of the demethylesterified homogalacturonans (HGAs) denoted the activity of the pectin methylesterases (PMEs) during the senescent phase, and was a novel time-based detection linked to the increased rigidity of the cell walls, and to the gall opening. Current investigation firstly reports the influence of immunocytochemistry of plant cell walls over the development of leaf tissues, determining their neo-ontogenesis towards a new phenotype, i.e., the globoid gall morphotype.

  11. 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.

  12. Biochemical Changes in Terminal Root Galls Caused by an Ectoparasitic Nematode, Longidorus africanus: Amino Acids.

    PubMed

    Epstein, E; Cohn, E

    1971-10-01

    The amino acids of terminal root galls caused by Longidorus africanus on bur marigold (Bidens tripartita L.) and grapevine (Vitis vinifera L.) were studied. The galled roots of bur marigold contained 73% more cell-wall protein and 184% more free amino acids. The main changes among the free amino acids of the galled tissue were a large increase (1900%) in proline and a decrease in aspartic acid (56%) compared with the respective check tissue. Hydroxyproline decreased in the wall protein fraction from 5.6% in the healthy tissue to 3.6% in the infected tissue.Percent of hydroxyproline in total amino acids of the wall protein fraction of grapevine roots decreased from 0.7% in the healthy tissue to 0.3% in the galled tissue, and total proteins of this fraction decreased from 9.5 mg to 4.5 rag, respectively. Total protein in the protoplasmic fraction also decreased from 3.0 mg in healthy to 1.0 mg in infected roots. No change was noticed in total proteins in the free amino acids fraction but free proline decreased 40% in the infected roots.The relationship of these differences to the specific reactions of the hosts to nematode feeding is discussed.

  13. Microstructure, mechanical and fretting wear properties of TiC-stainless steel composites

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

    Akhtar, F.; Department of Metallurgical and Materials Engineering, University of Engineering and Technology, Lahore; Guo, S.J.

    2008-01-15

    This study deals with the processing, microstructure, and wear behavior of TiC-reinforced stainless steel matrix composites, containing 50 to 70 wt.% TiC. Powder technology was used to successfully fabricate the composites. The microstructure of the composite was characterized by scanning electron microscopy. The microstructural study revealed that the TiC particles were distributed uniformly in the steel matrix phase. Interface debonding and microcracks were not observed in the composite. The composite hardness increased with TiC content. The fretting wear resistance of the composites was studied against high speed steel. The wear mechanisms are discussed by means of microscopical observations on themore » worn surfaces. The wear was severe at higher wear loads and lower TiC content. Microplowing of the stainless steel matrix was found to be the dominant wear mechanism. Heavy microplowing and rapid removal of material from the wear surface was observed at high wear load. The variation of wear loss with volume fraction and mean free path of the binder phase is also reported.« less

  14. Cecidonius pampeanus, gen. et sp. n.: an overlooked and rare, new gall-inducing micromoth associated with Schinus in southern Brazil (Lepidoptera, Cecidosidae).

    PubMed

    Moreira, Gilson R P; Eltz, Rodrigo P; Pase, Ramoim B; Silva, Gabriela T; Bordignon, Sérgio A L; Mey, Wolfram; Gonçalves, Gislene L

    2017-01-01

    Galls induced by the larval stage of cecidosids (Lepidoptera: Cecidosidae) are complex, multi-trophic systems, still poorly studied. They may be associated with other insect feeding guilds, including inquilines, kleptoparasites, cecidophages, parasitoids, and predators. By causing death of the gall inducer early in life and altering the gall phenotype, inquilines may lead to misidentification of the true gall inducers. Here, we describe through light and scanning electron microscopy Cecidonius pampeanus , a new genus and species of cecidosid moth, from the Pampa biome, south Brazil. It induces unnoticed, small galls under swollen stems of Schinus weinmannifolius Mart. ex Engl. (Anacardiaceae). Such galls are severely attacked early in ontogeny either by unidentified parasitoids belonging to Lyrcus Walker (Pteromalidae) that feed upon the inducer, or by inquiline wasps of the genus Allorhogas Gahan (Braconidae). The inquilines modify the galls into large ones that last longer and promptly call attention. Free-living galls are rare and dehiscent, pupation of C. pampeanus occurring on the ground. Due to these reasons the true inducer has been overlooked in this case for more than a century. Additionally we inferred a phylogeny for Cecidosidae using sequences from mitochondrial and nuclear loci, and characterized genetic variation and gene flow across ten populations. Despite its natural history similarities with the African genus Scyrotis , Cecidonius is a much younger lineage, more closely related to the Neotropical cecidosids. C. pampeanus populations, which are now confined to a few mountain areas within its distribution range due to habitat destruction, are also genetically isolated, requiring conservation measures.

  15. Cecidonius pampeanus, gen. et sp. n.: an overlooked and rare, new gall-inducing micromoth associated with Schinus in southern Brazil (Lepidoptera, Cecidosidae)

    PubMed Central

    Moreira, Gilson R.P.; Eltz, Rodrigo P.; Pase, Ramoim B.; Silva, Gabriela T.; Bordignon, Sérgio A.L.; Mey, Wolfram; Gonçalves, Gislene L.

    2017-01-01

    Abstract Galls induced by the larval stage of cecidosids (Lepidoptera: Cecidosidae) are complex, multi-trophic systems, still poorly studied. They may be associated with other insect feeding guilds, including inquilines, kleptoparasites, cecidophages, parasitoids, and predators. By causing death of the gall inducer early in life and altering the gall phenotype, inquilines may lead to misidentification of the true gall inducers. Here, we describe through light and scanning electron microscopy Cecidonius pampeanus, a new genus and species of cecidosid moth, from the Pampa biome, south Brazil. It induces unnoticed, small galls under swollen stems of Schinus weinmannifolius Mart. ex Engl. (Anacardiaceae). Such galls are severely attacked early in ontogeny either by unidentified parasitoids belonging to Lyrcus Walker (Pteromalidae) that feed upon the inducer, or by inquiline wasps of the genus Allorhogas Gahan (Braconidae). The inquilines modify the galls into large ones that last longer and promptly call attention. Free-living galls are rare and dehiscent, pupation of C. pampeanus occurring on the ground. Due to these reasons the true inducer has been overlooked in this case for more than a century. Additionally we inferred a phylogeny for Cecidosidae using sequences from mitochondrial and nuclear loci, and characterized genetic variation and gene flow across ten populations. Despite its natural history similarities with the African genus Scyrotis, Cecidonius is a much younger lineage, more closely related to the Neotropical cecidosids. C. pampeanus populations, which are now confined to a few mountain areas within its distribution range due to habitat destruction, are also genetically isolated, requiring conservation measures. PMID:29134006

  16. An Investigation on the Wear Resistance and Fatigue Behaviour of Ti-6Al-4V Notched Members Coated with Hydroxyapatite Coatings

    PubMed Central

    Oskouei, Reza H; Fallahnezhad, Khosro; Kuppusami, Sushmitha

    2016-01-01

    In this study, surface properties of Ti-6Al-4V alloy coated with hydroxyapatite coatings were investigated. Wear resistance and fatigue behaviour of samples with coating thicknesses of 10 and 50 µm as well as uncoated samples were examined. Wear experiments demonstrated that the friction factor of the uncoated titanium decreased from 0.31 to 0.06, through a fluctuating trend, after 50 cycles of wear tests. However, the friction factor of both the coated samples (10 and 50 µm) gradually decreased from 0.20 to 0.12 after 50 cycles. At the end of the 50th cycle, the penetration depth of the 10 and 50 µm coated samples were 7.69 and 6.06 µm, respectively. Fatigue tests showed that hydroxyapatite coatings could improve fatigue life of a notched Ti-6Al-4V member in both low and high cycle fatigue zones. It was understood, from fractography of the fracture surfaces, that the fatigue zone of the uncoated specimens was generally smaller in comparison with that of the coated specimens. No significant difference was observed between the fatigue life of coated specimens with 10 and 50 µm thicknesses. PMID:28787911

  17. Nuclear power plant Generic Aging Lessons Learned (GALL). Main report and appendix A

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

    Kaza, K.E.; Diercks, D.R.; Holland, J.W.

    The purpose of this generic aging lessons learned (GALL) review is to provide a systematic review of plant aging information in order to assess materials and component aging issues related to continued operation and license renewal of operating reactors. Literature on mechanical, structural, and thermal-hydraulic components and systems reviewed consisted of 97 Nuclear Plant Aging Research (NPAR) reports, 23 NRC Generic Letters, 154 Information Notices, 29 Licensee Event Reports (LERs), 4 Bulletins, and 9 Nuclear Management and Resources Council Industry Reports (NUMARC IRs) and literature on electrical components and systems reviewed consisted of 66 NPAR reports, 8 NRC Generic Letters,more » 111 Information Notices, 53 LERs, 1 Bulletin, and 1 NUMARC IR. More than 550 documents were reviewed. The results of these reviews were systematized using a standardized GALL tabular format and standardized definitions of aging-related degradation mechanisms and effects. The tables are included in volume s 1 and 2 of this report. A computerized data base has also been developed for all review tables and can be used to expedite the search for desired information on structures, components, and relevant aging effects. A survey of the GALL tables reveals that all ongoing significant component aging issues are currently being addressed by the regulatory process. However, the aging of what are termed passive components has been highlighted for continued scrutiny. This document is Volume 1, consisting of the executive summary, summary and observations, and an appendix listing the GALL literature review tables.« less

  18. Self-Lubricating, Wear-Resistant Diamond Films Developed for Use in Vacuum Environment

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Diamond's outstanding properties--extreme hardness, chemical and thermal inertness, and high strength and rigidity--make it an ideal material for many tribological applications, such as the bearings, valves, and engine parts in the harsh environment found in internal-combustion engines, jet engines, and space propulsion systems. It has been demonstrated that chemical-vapor-deposited diamond films have low coefficients of friction (on the order of 0.01) and low wear rates (less than 10(sup -7) mm (sup 3/N-m)) both in humid air and dry nitrogen but that they have both high coefficients of friction (greater than 0.4) and high wear rates (on the order of 1(sup -4) mm sup 3/N-m)) in vacuum. It is clear that surface modifications that provide acceptable levels of friction and wear properties will be necessary before diamond films can be used for tribological applications in a space-like, vacuum environment. Previously, it was found that coatings of amorphous, non-diamond carbon can provide low friction in vacuum. Therefore, to reduce the friction and wear of diamond film in vacuum, carbon ions were implanted in an attempt to form a surface layer of amorphous carbon phases on the diamond films.

  19. Characterization of wear debris generated in accelerated rolling-element fatigue tests

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Parker, R. J.

    1978-01-01

    A ferrographic analysis was used to determine the types and quantities of wear debris generated during accelerated rolling contact fatigue tests. The five-ball rolling contact fatigue tester was used. Ball specimens were made of a corrosion resistant, high-temperature bearing steel. The lubricant was a superrefined naphthenic mineral oil. Conditions included a maximum Hertz stress of 5.52 10 to the 9th power Pa and a shaft speed of 10,000 rpm. Four types of wear debris were observed: (1) normal rubbing wear particles, (2) fatigue microspall particles, (3) spheres, and (4) friction polymer deposits. The characterization of wear debris as a function of time was of limited use in predicting fatigue failures in these accelerated tests.

  20. Genetic and QTL analysis of resistance to Xiphinema index in a grapevine cross.

    PubMed

    Xu, K; Riaz, S; Roncoroni, N C; Jin, Y; Hu, R; Zhou, R; Walker, M A

    2008-01-01

    Resistance to the dagger nematode Xiphinema index has been an important objective in grape rootstock breeding programs. This nematode not only causes severe feeding damage to the root system, but it also vectors grapevine fanleaf virus (GFLV), the causal agent of fanleaf degeneration and one of the most severe viral diseases of grape. The established screening procedures for dagger nematode resistance are time consuming and can produce inconsistent results. A fast and reliable greenhouse-based system for screening resistance to X. index that is suitable for genetic studies and capable of evaluating breeding populations is needed. In this report, the dynamics of nematode numbers, gall formation, and root weight loss were investigated using a variety of soil mixes and pot sizes over a 52-week period. Results indicated that the number of galls formed was correlated with the size of the nematode population and with the degree of root weight loss. After inoculation with 100 nematodes, gall formation could be reliably evaluated in 4-8 weeks in most plant growth conditions and results were obtained 6 months more rapidly than past evaluation methods. This modified X. index resistance screening method was successfully applied to 185 of the 188 F(1) progeny from a cross of D8909-15 x F8909-17 (the 9621 population), which segregates for a form of X. index resistance originally derived from Vitis arizonica. Quantitative trait loci (QTL) analysis was carried out on both parental genetic maps of 255 markers using MapQTL 4.0. Results revealed that X. index resistance is controlled by a major QTL, designated Xiphinema index Resistance 1 (XiR1), near marker VMC5a10 on chromosome 19. The XiR1 QTL was supported by a LOD score of 36.9 and explained 59.9% of the resistance variance in the mapping population.

  1. Anatomical and phenological implications of the relationship between Schinus polygama (Cav.) (Cabrera) and the galling insect Calophya rubra (Blanchard).

    PubMed

    Guedes, L M; Aguilera, N; Ferreira, B G; Becerra, J; Hernández, V; Isaias, R M S

    2018-05-01

    The success of galling insects could be determined by synchronisation with host plant phenology and climate conditions, ensuring suitable oviposition sites for gall induction and food resources for their survival. The anatomical, histochemical and phenological synchronisation strategies between Calophya rubra (Blanchard) (Hemiptera: Psylloidea) and its host, the evergreen plant Schinus polygama (Cav.) (Cabrera) (Anacardiaceae), in the Mediterranean climate of southern Chile was evaluated and compared to that of the congeneric C. cf. duvauae (Scott) from Brazil and closely related host plant S. engleri in a subtropical climate. Anatomical, histometric, histochemical and vegetative phenology studies of the stem and galls were conducted from June 2015 to December 2016. Based on the anatomical, histometric and histochemical analysis, the conical stem gall traits imply gains over the non-galled stem toward the galling insect survival, but the maintenance of phellem, secretory ducts and pith indicate conservative developmental traits that cannot be manipulated by C. rubra. Our results indicate that the conditions of the Mediterranean climate zone limit C. rubra immature activity during unfavourable periods, probably determining a diapause period and a univoltine life cycle, which are peculiarities of the S. polygama- C. rubra system. The synchronisation between development and seasonality confers peculiarities to the S. polygama- C. rubra system in the Mediterranean climate zone. © 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

  2. Diverse Filters to Sense: Great Variability of Antennal Morphology and Sensillar Equipment in Gall-Wasps (Hymenoptera: Cynipidae)

    PubMed Central

    Polidori, Carlo; Nieves-Aldrey, José L.

    2014-01-01

    Comparative studies on antennal sensillar equipment in insects are largely lacking, despite their potential to provide insights into both ecological and phylogenetic relationships. Here we present the first comparative study on antennal morphology and sensillar equipment in female Cynipoidea (Hymenoptera), a large and diverse group of wasps, with special reference to the so-called gall-wasps (Cynipidae). A SEM analysis was conducted on 51 species from all extant cynipoid families and all cynipid tribes, and spanning all known life-histories in the superfamily (gall-inducers, gall-inquilines, and non-gall associated parasitoids). The generally filiform, rarely clavate, antennal flagellum of Cynipoidea harbours overall 12 types of sensilla: s. placoidea (SP), two types of s. coeloconica (SCo-A, SCo-B), s. campaniformia (SCa), s. basiconica (SB), five types of s. trichoidea (ST-A, B, C, D, E), large disc sensilla (LDS) and large volcano sensilla (LVS). We found a great variability in sensillar equipment both among and within lineages. However, few traits seem to be unique to specific cynipid tribes. Paraulacini are, for example, distinctive in having apical LVS; Pediaspidini are unique in having ≥3 rows of SP, each including 6–8 sensilla per flagellomere, and up to 7 SCo-A in a single flagellomere; Eschatocerini have by far the largest SCo-A. Overall, our data preliminarily suggest a tendency to decreased numbers of SP rows per flagellomere and increased relative size of SCo-A during cynipoid evolution. Furthermore, SCo-A size seems to be higher in species inducing galls in trees than in those inducing galls in herbs. On the other hand, ST seem to be more abundant on the antennae of herb-gallers than wood-gallers. The antennal morphology and sensillar equipment in Cynipoidea are the complex results of different interacting pressures that need further investigations to be clarified. PMID:25003514

  3. Ferrographic analysis of wear debris generated in accelerated rolling element fatigue tests

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Parker, R. J.

    1977-01-01

    The types and quantities of wear particles generated during accelerated ball rolling contact fatigue tests were determined. Ball specimens were made of AMS 5749, a corrosion resistant, high-temperature bearing steel. The lubricant was a super-refined naphthenic mineral oil. Conditions included a maximum Hertz stress of 5.215 times 10 to the 9th power Pa and a shaft speed of 10,000 rpm. Four types of wear particles were observed; normal rubbing wear particles, fatigue spall particles, spheres, and friction polymer.

  4. Insect-induced effects on plants and possible effectors used by galling and leaf-mining insects to manipulate their host-plant.

    PubMed

    Giron, David; Huguet, Elisabeth; Stone, Graham N; Body, Mélanie

    2016-01-01

    Gall-inducing insects are iconic examples in the manipulation and reprogramming of plant development, inducing spectacular morphological and physiological changes of host-plant tissues within which the insect feeds and grows. Despite decades of research, effectors involved in gall induction and basic mechanisms of gall formation remain unknown. Recent research suggests that some aspects of the plant manipulation shown by gall-inducers may be shared with other insect herbivorous life histories. Here, we illustrate similarities and contrasts by reviewing current knowledge of metabolic and morphological effects induced on plants by gall-inducing and leaf-mining insects, and ask whether leaf-miners can also be considered to be plant reprogrammers. We review key plant functions targeted by various plant reprogrammers, including plant-manipulating insects and nematodes, and functionally characterize insect herbivore-derived effectors to provide a broader understanding of possible mechanisms used in host-plant manipulation. Consequences of plant reprogramming in terms of ecology, coevolution and diversification of plant-manipulating insects are also discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Sliding wear and corrosion behaviour of alloyed austempered ductile iron subjected to novel two step austempering treatment

    NASA Astrophysics Data System (ADS)

    Sethuram, D.; Srisailam, Shravani; Rao Ponangi, Babu

    2018-04-01

    Austempered Ductile Iron(ADI) is an exciting alloy of iron which offers the design engineers the best combination high strength-to-weight ratio, low cost design flexibility, good toughness, wear resistance along with fatigue strength. The two step austempering procedure helps in simultaneously improving the tensile strength as-well as the ductility to more than that of the conventional austempering process. Extensive literature survey reveals that it’s mechanical and wear behaviour are dependent on heat treatment and alloy additions. Current work focuses on characterizing the two-step ADI samples (TSADI) developed by novel heat treatment process for resistance to corrosion and wear. The samples of Ductile Iron were austempered by the two-Step Austempering process at temperatures 300°C to 450°C in the steps of 50°C.Temperaturesare gradually increased at the rate of 14°C/Hour. In acidic medium (H2SO4), the austempered samples showed better corrosive resistance compared to conventional ductile iron. It has been observed from the wear studies that TSADI sample at 350°C is showing better wear resistance compared to ductile iron. The results are discussed in terms of fractographs, process variables and microstructural features of TSADI samples.

  6. Terminal-instar larval systematics and biology of west European species of Ormyridae associated with insect galls (Hymenoptera, Chalcidoidea)

    PubMed Central

    Gómez, Jose F.; Nieves, María Hernández; Gayubo, Severiano F.; Nieves-Aldrey, Jose Luis

    2017-01-01

    Abstract A systematic study of the genus Ormyrus (Chalcidoidea, Ormyridae) was conducted based on the morphology and biology of the terminal-instar larvae of ten west European species that are parasitoids of gall wasps and gallflies of the families Cynipidae, Eurytomidae and Tephritidae. The first detailed descriptions are provided of the terminal-instar larvae of these ten species using SEM images to illustrate diagnostic characters with systematic values. A key is provided for the identification of ormyrid larvae associated with galls in Europe, which is based particularly on characters of the head, mouthparts and mandibles. Although only limited informative variation in body shape was found, the setation of the head provided several characters of potential taxonomic value. The larval biology of the ten ormyrid species inhabiting different galls is also summarised. Although Ormyrus larvae are usually solitary idiobiont ectoparasitoids of the host larva of various gall-inhabiting insects, evidence of secondary phytophagy was observed in some species. PMID:28144185

  7. Degradation of titanium drillpipe from corrosion and wear

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

    Ferg, T.E.; Aldrich, C.S.; Craig, B.D.

    1993-06-01

    Drilling deeper than 35,000 ft is limited by the extreme hook loads of steel drillpipe and temperature constraints of aluminum drillpipe. Titanium Alloys Ti-6Al-4V and Beta C have been proposed for use in drillpipe for wells deeper than 35,000 ft because of their high strength/weight ratios, superior high-temperature corrosion resistance, and thermal stability. Their suitability in drilling environments, however, has not been evaluated. To determine the corrosion and wear characteristics of two types of titanium-alloy drillpipe under dogleg conditions, a test cell was constructed to test titanium drillpipe joints in contact with API Spec. 5CT Grade P-110 casing in differentmore » drilling muds. Titanium-alloy pipe and Grade P-110 casing wear rates were measured, and tests showed that both titanium-alloy pipes exhibited much greater wear than did steel drillpipe in water-based mud under the same conditions. Test data showed that the total wear rate of Alloys Ti-6Al-4V and Beta C in a drilling environment is a combination of mechanical wear and corrosion.« less

  8. The mono - and sesquiterpene content of aphid-induced galls on Pistacia palaestina is not a simple reflection of their composition in intact leaves.

    PubMed

    Rand, Karin; Bar, Einat; Ben-Ari, Matan; Lewinsohn, Efraim; Inbar, Moshe

    2014-06-01

    Pistacia palaestina Boiss. (Anacardiaceae), a sibling species of P. terebinthus also known as turpentine tree or terebinth tree, is common in the Levant region. The aphid Baizongia pistaciae L. manipulates the leaves of the plant to form large galls, which provide both food and protection for its developing offspring. We analyzed the levels and composition of mono-and sesquiterpenes in both leaves and galls of ten naturally growing trees. Our results show that monoterpene hydrocarbons are the main constituents of P. palaestina leaves and galls, but terpene levels and composition vary among trees. Despite this inter-tree variation, terpene levels and compositions in galls from different trees resemble each other more than the patterns displayed by leaves from the same trees. Generally, galls contain 10 to 60 fold higher total terpene amounts than leaves, especially of the monoterpenes α-pinene and limonene. Conversely, the leaves generally accumulate more sesquiterpenes, in particular E-caryophyllene, germacrene D and δ-cadinene, in comparison to galls. Our results clearly show that the terpene pattern in the galls is not a simple reflection of that of the leaves and suggest that aphids have a strong impact on the metabolism of their host plant, possibly for their own defense.

  9. Effects of crystal refining on wear behaviors and mechanical properties of lithium disilicate glass-ceramics.

    PubMed

    Zhang, Zhenzhen; Guo, Jiawen; Sun, Yali; Tian, Beimin; Zheng, Xiaojuan; Zhou, Ming; He, Lin; Zhang, Shaofeng

    2018-05-01

    The purpose of this study is to improve wear resistance and mechanical properties of lithium disilicate glass-ceramics by refining their crystal sizes. After lithium disilicate glass-ceramics (LD) were melted to form precursory glass blocks, bar (N = 40, n = 10) and plate (N = 32, n = 8) specimens were prepared. According to the differential scanning calorimetry (DSC) of precursory glass, specimens G1-G4 were designed to form lithium disilicate glass-ceramics with different crystal sizes using a two-step thermal treatment. In the meantime, heat-pressed lithium disilicate glass-ceramics (GC-P) and original ingots (GC-O) were used as control groups. Glass-ceramics were characterized using X-ray diffraction (XRD) and were tested using flexural strength test, nanoindentation test and toughness measurements. The plate specimens were dynamically loaded in a chewing simulator with 350 N up to 2.4 × 10 6 loading cycles. The wear analysis of glass-ceramics was performed using a 3D profilometer after every 300,000 wear cycles. Wear morphologies and microstructures were analyzed by scanning electron microscopy (SEM). One-way analysis of variance (ANOVA) was used to analyze the data. Multiple pairwise comparisons of means were performed by Tukey's post-hoc test. Materials with different crystal sizes (p < 0.05) exhibited different properties. Specifically, G3 with medium-sized crystals presented the highest flexural strength, hardness, elastic modulus and fracture toughness. G1 and G2 with small-sized crystals showed lower flexural strength, whereas G4, GC-P, and GC-O with large-sized crystals exhibited lower hardness and elastic modulus. The wear behaviors of all six groups showed running-in wear stage and steady wear stage. G3 showed the best wear resistance while GC-P and GC-O exhibited the highest wear volume loss. After crystal refining, lithium disilicate glass-ceramic with medium-sized crystals showed the highest wear resistance and mechanical

  10. Three-body wear of a hand-consolidated silver alternative to amalgam.

    PubMed

    Xu, H H; Eichmiller, F C; Giuseppetti, A A; Ives, L K; Parry, E E; Schumacher, G E

    1999-09-01

    Recent studies have investigated a mercury-free silver alternative to amalgam, but the silver powders required a relatively high compaction pressure to consolidate. The aim of the present study was to consolidate a precipitated silver powder into a cohesive solid using an air-driven pneumatic condenser fitted with an amalgam plugger at a clinically realistic load, and to study the mechanisms and rates of three-body wear of the consolidated silver in comparison with that of an amalgam. The silver powder was annealed, rinsed with a dilute acid, and consolidated either in a prepared tooth cavity or in a specimen mold at a load of 15 N. A four-station wear machine was used where each specimen was immersed in a slurry containing polymethyl methacrylate beads, then a steel pin was loaded and rotated against the specimen at a maximum load of 76 N. The flexural strength in MPa (mean +/- SD; n = 10) was 86 +/- 20 for amalgam, 181 +/- 45 for silver with a polished surface, and 202 +/- 21 for silver with a burnished surface. After 4 x 10(5) wear cycles, the wear scar depth in microm was 134 +/- 54 for amalgam, 143 +/- 8 for polished silver, and 131 +/- 9 for burnished silver, which were not significantly different (Tukey's multiple comparison test; family confidence coefficient = 0.95). SEM examination revealed cracks and fracture pits in the worn surface of amalgam, in contrast to a smooth surface in silver. Wear and material removal in amalgam occurred by microfracture and dislodgement of cracked segments, while wear in the silver occurred by ductile deformation and flow of materials. To conclude, the consolidated silver possesses a three-body wear resistance similar to that of amalgam, and a higher resistance to wear-induced damage and cracking than amalgam. The mechanism of wear in amalgam is microfracture and material dislodgement, while that in consolidated silver is ductile deformation and flow of material.

  11. Serine Proteases-Like Genes in the Asian Rice Gall Midge Show Differential Expression in Compatible and Incompatible Interactions with Rice

    PubMed Central

    Sinha, Deepak Kumar; Lakshmi, Mulagondla; Anuradha, Ghanta; Rahman, Shaik J.; Siddiq, Ebrahimali A.; Bentur, Jagadish S.; Nair, Suresh

    2011-01-01

    The Asian rice gall midge, Orseolia oryzae (Wood-Mason), is a serious pest of rice. Investigations into the gall midge-rice interaction will unveil the underlying molecular mechanisms which, in turn, can be used as a tool to assist in developing suitable integrated pest management strategies. The insect gut is known to be involved in various physiological and biological processes including digestion, detoxification and interaction with the host. We have cloned and identified two genes, OoprotI and OoprotII, homologous to serine proteases with the conserved His87, Asp136 and Ser241 residues. OoProtI shared 52.26% identity with mosquito-type trypsin from Hessian fly whereas OoProtII showed 52.49% identity to complement component activated C1s from the Hessian fly. Quantitative real time PCR analysis revealed that both the genes were significantly upregulated in larvae feeding on resistant cultivar than in those feeding on susceptible cultivar. These results provide an opportunity to understand the gut physiology of the insect under compatible or incompatible interactions with the host. Phylogenetic analysis grouped these genes in the clade containing proteases of phytophagous insects away from hematophagous insects. PMID:21686154

  12. 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

  13. Ultralow nanoscale wear through atom-by-atom attrition in silicon-containing diamond-like carbon

    NASA Astrophysics Data System (ADS)

    Bhaskaran, Harish; Gotsmann, Bernd; Sebastian, Abu; Drechsler, Ute; Lantz, Mark A.; Despont, Michel; Jaroenapibal, Papot; Carpick, Robert W.; Chen, Yun; Sridharan, Kumar

    2010-03-01

    Understanding friction and wear at the nanoscale is important for many applications that involve nanoscale components sliding on a surface, such as nanolithography, nanometrology and nanomanufacturing. Defects, cracks and other phenomena that influence material strength and wear at macroscopic scales are less important at the nanoscale, which is why nanowires can, for example, show higher strengths than bulk samples. The contact area between the materials must also be described differently at the nanoscale. Diamond-like carbon is routinely used as a surface coating in applications that require low friction and wear because it is resistant to wear at the macroscale, but there has been considerable debate about the wear mechanisms of diamond-like carbon at the nanoscale because it is difficult to fabricate diamond-like carbon structures with nanoscale fidelity. Here, we demonstrate the batch fabrication of ultrasharp diamond-like carbon tips that contain significant amounts of silicon on silicon microcantilevers for use in atomic force microscopy. This material is known to possess low friction in humid conditions, and we find that, at the nanoscale, it is three orders of magnitude more wear-resistant than silicon under ambient conditions. A wear rate of one atom per micrometre of sliding on SiO2 is demonstrated. We find that the classical wear law of Archard does not hold at the nanoscale; instead, atom-by-atom attrition dominates the wear mechanisms at these length scales. We estimate that the effective energy barrier for the removal of a single atom is ~1 eV, with an effective activation volume of ~1 × 10-28 m.

  14. Investigation of the mechanical properties of FeNiCrMnSi high entropy alloy wear resistant

    NASA Astrophysics Data System (ADS)

    Buluc, G.; Florea, I.; Chelariu, R.; Popescu, G.; Carcea, I.

    2016-06-01

    In this paper we investigated microstructure, hardness and wear resistance for FeNiCrMnAl, high entropy alloy. The FeNiCrMnSi, high entropy alloy was elaborated in a medium induction furnace, by choosing the silicon, as an alliance element within the equi- atomic high entropy alloy, we managed to obtain a dendritic structure, the formation of intermetallic compounds or separated silicon. The medium hardness value of the investigated alloy was 948.33 HV and the medium value of the friction coefficient was 0.6655 in the first 20 seconds and 0.5425 for 1667 seconds. The volume loss of the high entropy alloy FeNiCrMnSi was 0.0557 mm3.

  15. 77 FR 46127 - Interim Staff Guidance on Changes to the Generic Aging Lessons Learned (GALL) Report Revision 2...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-02

    ... Aging Lessons Learned (GALL) Report Revision 2 AMP XI.M41, ``Buried and Underground Piping and Tanks... AMPs in NUREG-1801, Revision 2, ``Generic Aging Lessons Learned (GALL) Report,'' and the NRC staff's... issues LR-ISG to communicate insights and lessons learned and to address emergent issues not covered in...

  16. 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.

  17. Leaf-Mining and Gall-Forming Insects: Tools for Teaching Population Ecology.

    ERIC Educational Resources Information Center

    Brown, Valerie K.

    1984-01-01

    Discusses the use of leaf mines (formed by larvae of small moths or flies) and galls (wasps' larvae) in various insect population studies. Also considers the advantages of using these structures for instructional purposes. (DH)

  18. Fretting wear behaviors of a dual-cooled nuclear fuel rod under a simulated rod vibration

    NASA Astrophysics Data System (ADS)

    Lee, Young-Ho; Kim, Hyung-Kyu; Kang, Heung-Seok; Yoon, Kyung-Ho; Kim, Jae-Yong; Lee, Kang-Hee

    2012-06-01

    Recently, a dual-cooled fuel (i.e., annular fuel) that is compatible with current operating PWR plants has been proposed in order to realize both a considerable amount of power uprating and an increase of safety margins. As the design concept should be compatible with current operating PWR plants, however, it shows a narrow gap between the fuel rods when compared with current solid nuclear fuel arrays and needs to modify the spacer grid shapes and their positions. In this study, fretting wear tests have been performed to evaluate the wear resistance of a dual-cooled fuel by using a proposed spring and dimple of spacer grids that have a cantilever type and hemispherical shape, respectively. As a result, the wear volume of the spring specimen gradually increases as the contact condition is changed from a certain gap, just contact to positive force. However, in the dimple specimen, just contact condition shows a large wear volume. In addition, a circular rod motion at upper region of contact surface is gradually increased and its diametric size depends on the wear depth increase. Based on the test results, the fretting wear resistance of the proposed spring and dimple is analyzed by comparing the wear measurement results and rod motion in detail.

  19. Mechanisms Driving Galling Success in a Fragmented Landscape: Synergy of Habitat and Top-Down Factors along Temperate Forest Edges

    PubMed Central

    Kelch, Nina-S.; Neves, Frederico S.; Fernandes, G. Wilson

    2016-01-01

    Edge effects play key roles in the anthropogenic transformation of forested ecosystems and their biota, and are therefore a prime field of contemporary fragmentation research. We present the first empirical study to address edge effects on the population level of a widespread galling herbivore in a temperate deciduous forest. By analyzing edge effects on abundance and trophic interactions of beech gall midge (Mikiola fagi Htg.), we found 30% higher gall abundance in the edge habitat as well as lower mortality rates due to decreased top-down control, especially by parasitoids. Two GLM models with similar explanatory power (58%) identified habitat specific traits (such as canopy closure and altitude) and parasitism as the best predictors of gall abundance. Further analyses revealed a crucial influence of light exposure (46%) on top-down control by the parasitoid complex. Guided by a conceptual framework synthesizing the key factors driving gall density, we conclude that forest edge proliferation of M. fagi is due to a complex interplay of abiotic changes and trophic control mechanisms. Most prominently, it is caused by the microclimatic regime in forest edges, acting alone or in synergistic concert with top-down pressure by parasitoids. Contrary to the prevailing notion that specialists are edge-sensitive, this turns M. fagi into a winner species in fragmented temperate beech forests. In view of the increasing proportion of edge habitats and the documented benefits from edge microclimate, we call for investigations exploring the pest status of this galling insect and the modulators of its biological control. PMID:27310599

  20. Improving the corrosion wear resistance of AISI 316L stainless steel by particulate reinforced Ni matrix composite alloying layer

    NASA Astrophysics Data System (ADS)

    Xu, Jiang; Zhuo, Chengzhi; Tao, Jie; Jiang, Shuyun; Liu, Linlin

    2009-01-01

    In order to overcome the problem of corrosion wear of AISI 316L stainless steel (SS), two kinds of composite alloying layers were prepared by a duplex treatment, consisting of Ni/nano-SiC and Ni/nano-SiO2 predeposited by brush plating, respectively, and subsequent surface alloying with Ni-Cr-Mo-Cu by a double glow process. The microstructure of the two kinds of nanoparticle reinforced Ni-based composite alloying layers was investigated by means of SEM and TEM. The electrochemical corrosion behaviour of composite alloying layers compared with the Ni-based alloying layer and 316L SS under different conditions was characterized by potentiodynamic polarization test and electrochemical impedance spectroscopy. Results showed that under alloying temperature (1000 °C) conditions, amorphous nano-SiO2 particles still retained the amorphous structure, whereas nano-SiC particles were decomposed and Ni, Cr reacted with SiC to form Cr6.5Ni2.5Si and Cr23C6. In static acidic solution, the corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiO2 particles interlayer is lower than that of the Ni-based alloying layer. However, the corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiO2 particles interlayer is prominently superior to that of the Ni-based alloying layer under acidic flow medium condition and acidic slurry flow condition. The corrosion resistance of the composite alloying layer with the brush plating Ni/nano-SiC particles interlayer is evidently lower than that of the Ni-based alloying layer, but higher than that of 316L SS under all test conditions. The results show that the highly dispersive nano-SiO2 particles are helpful in improving the corrosion wear resistance of the Ni-based alloying layer, whereas carbides and silicide phase are deleterious to that of the Ni-based alloying layer due to the fact that the preferential removal of the matrix around the precipitated phase takes place by the chemical

  1. Effects of environmental parameters on the chestnut gall wasp and its complex of indigenous parasitoids

    NASA Astrophysics Data System (ADS)

    Bonsignore, Carmelo Peter; Bernardo, Umberto

    2018-04-01

    The chestnut gall wasp (CGW), Dryocosmus kuriphilus, an invasive pest native to China, has caused severe yield and economic losses to chestnut production in Europe since its arrival in 2002. In Southern Italy, the complex of indigenous parasitoids colonizing CGW was monitored between 2013 and 2015, with the aim of estimating the composition of the indigenous parasitoid complex, its ability to control CGW populations, and the interactions of both factors with several measured environmental parameters. We compared results among three differently managed field types. Results showed an increase in the rate of parasitism both when the host population density was lower and in unmanaged chestnut stands with more natural conditions. The percentage of parasitism in galls was related to morphological traits of the galls and to higher seasonal temperatures, which reduced the parasitism intensity because CGW develops earlier under such conditions. The host-parasitoid mortality inside galls varied among sites and was associated mostly with rot fungi during wet spring and summer months. Parasitoid species richness was similar among the study sites, but the proportion of parasitoid species differed between orchards and unmanaged coppice stands. The timing of attack by parasitoids followed a species-specific successional sequence throughout the larva-to-adult life cycle of the CGW. These interactions should be considered in future research on trophic relationships and when modeling invasive scenarios for new pest species.

  2. Starch characteristics influencing resistant starch content of cooked buckwheat groats

    USDA-ARS?s Scientific Manuscript database

    Enzyme resistant starch (RS), owing to its health benefits such as colon cancer inhibition, reduced glycemic response, reduced cholesterol level, prevention of gall stone formation and obesity, has received an increasing attention from consumers and food manufacturers, whereas intrinsic and extrinsi...

  3. 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.

  4. Fabrication of wear-resistant silicon microprobe tips for high-speed surface roughness scanning devices

    NASA Astrophysics Data System (ADS)

    Wasisto, Hutomo Suryo; Yu, Feng; Doering, Lutz; Völlmeke, Stefan; Brand, Uwe; Bakin, Andrey; Waag, Andreas; Peiner, Erwin

    2015-05-01

    Silicon microprobe tips are fabricated and integrated with piezoresistive cantilever sensors for high-speed surface roughness scanning systems. The fabrication steps of the high-aspect-ratio silicon microprobe tips were started with photolithography and wet etching of potassium hydroxide (KOH) resulting in crystal-dependent micropyramids. Subsequently, thin conformal wear-resistant layer coating of aluminum oxide (Al2O3) was demonstrated on the backside of the piezoresistive cantilever free end using atomic layer deposition (ALD) method in a binary reaction sequence with a low thermal process and precursors of trimethyl aluminum and water. The deposited Al2O3 layer had a thickness of 14 nm. The captured atomic force microscopy (AFM) image exhibits a root mean square deviation of 0.65 nm confirming the deposited Al2O3 surface quality. Furthermore, vacuum-evaporated 30-nm/200-nm-thick Au/Cr layers were patterned by lift-off and served as an etch mask for Al2O3 wet etching and in ICP cryogenic dry etching. By using SF6/O2 plasma during inductively coupled plasma (ICP) cryogenic dry etching, micropillar tips were obtained. From the preliminary friction and wear data, the developed silicon cantilever sensor has been successfully used in 100 fast measurements of 5- mm-long standard artifact surface with a speed of 15 mm/s and forces of 60-100 μN. Moreover, the results yielded by the fabricated silicon cantilever sensor are in very good agreement with those of calibrated profilometer. These tactile sensors are targeted for use in high-aspect-ratio microform metrology.

  5. A novel method for isolation and recovery of ceramic nanoparticles and metal wear debris from serum lubricants at ultra-low wear rates.

    PubMed

    Lal, S; Hall, R M; Tipper, J L

    2016-09-15

    Ceramics have been used to deliver significant improvements in the wear properties of orthopaedic bearing materials, which has made it challenging to isolate wear debris from simulator lubricants. Ceramics such as silicon nitride, as well as ceramic-like surface coatings on metal substrates have been explored as potential alternatives to conventional implant materials. Current isolation methods were designed for isolating conventional metal, UHMWPE and ceramic wear debris. In this paper, we describe a methodology for isolation and recovery of ceramic or ceramic-like coating particles and metal wear particles from serum lubricants under ultra-low and low wear performance. Enzymatic digestion was used to digest the serum proteins and sodium polytungstate was used as a novel density gradient medium to isolate particles from proteins and other contaminants by ultracentrifugation. This method demonstrated over 80% recovery of particles and did not alter the size or morphology of ceramic and metal particles during the isolation process. Improvements in resistance to wear and mechanical damage of the articulating surfaces have a large influence on longevity and reliability of joint replacement devices. Modern ceramics have demonstrated ultra-low wear rates for hard-on-hard total hip replacements. Generation of very low concentrations of wear debris in simulator lubricants has made it challenging to isolate the particles for characterisation and further analysis. We have introduced a novel method to isolate ceramic and metal particles from serum-based lubricants using enzymatic digestion and novel sodium polytungstate gradients. This is the first study to demonstrate the recovery of ceramic and metal particles from serum lubricants at lowest detectable in vitro wear rates reported in literature. Copyright © 2016. Published by Elsevier Ltd.

  6. Ferrographic analysis of wear debris generated in accelerated rolling element fatigue tests

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Parker, R. J.

    1977-01-01

    Ferrographic analysis was used to determine the types and quantities of wear particles generated during accelerated rolling contact fatigue tests. The NASA five-ball rolling contact fatigue tester was used. Ball specimens were made of AMS 5749, a corrosion-resistant high-temperature bearing steel. The lubricant was a super-refined naphthenic mineral oil. Conditions included a maximum Hertz stress of 5.52 billion Pa and a shaft speed of 10,000 rpm. Four types of wear particles were observed: normal rubbing wear particles, fatigue spall particles, spheres, and friction polymer.

  7. Insects galls of Pantanal areas in the State of Mato Grosso do Sul, Brazil: characterization and occurrence.

    PubMed

    Ascendino, Sharlene; Maia, Valéria C

    2018-01-01

    Two Pantanal areas were investigated in Corumbá, Mato Grosso do Sul. The field works were carried out in five trails, in August and December/2011 and April/2012. Seventy-six gall morphotypes were found in 52 host plants, 22 of them were identified at species level and 30 at genus. Fabaceae, Myrtaceae and Sapindaceae were the plant families with the greatest richness of gall. Leaves were the plant organ with the greatest gall richness. Six gall shapes were found - globoid, lenticular, fusiform, cylindrical, conical, and marginal roll. The three first were the most common. Five colors were observed - green, brown, red, yellow, and black. Green and brown predominated. Most were glabrous and one-chambered. These features have been indicated in several Brazilian biomes. Diptera (Cecidomyiidae) were the most frequent gallers. The associated fauna comprised parasitoids (Eulophidae, Braconidae, Eupelmidae, Eurytomidae, Platygastridae, and Pteromalidae), inquilines (Cecidomyiidae: Trotteria Kieffer, 1902, Hymenoptera: Tanaostigmoides Ashmead, 1896, Hemiptera, Lepidoptera and Thysanoptera) and predators (Pseudoscorpionida: Olpiolum medium Beier, 1931, Cecidomyiidae: Lestodiplosini and Hymenoptera: Formicidae). Parasitoids were the most frequent. Multiparatism was observed. Our data represent the first contribution to the knowledge of the associated fauna in the Pantanal.

  8. A tri-layer thin film containing graphene oxide to protect zinc substrates from wear

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Gu, Zhengpeng; Yuan, Ningyi; Chu, Fuqiang; Cheng, Guanggui; Ding, Jianning

    2018-06-01

    Due to its excellent properties, Zn alloy is widely used in daily life. However, the poor wear-resisting properties of Zn alloys limits their application. In this paper, a tri-layer thin film consisting of 3-aminopropyltriethoxysilane (APS), graphene oxide (GO) and perfluoropolyethers (PFPE) were successfully prepared on the surface of Zn alloy to improve the wear-resisting properties. The as-prepared tri-layer thin films were characterized by atomic force microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy and contact angle measurement. In addition, the tribological properties of the as-prepared tri-layer thin films were studied on a ball-on-plate tribometer and the morphologies of worn surfaces were observed using 3D noncontact interferometric microscope. Compared with the control samples, the tri-layer thin films showed excellent friction-reducing and wear-resisting properties, which was attributed to the synergistic effect of the GO as the load-carrying layer and the PFPE as the lubricating layer.

  9. Life inside a gall: closeness does not favour horizontal transmission of Rickettsia between a gall wasp and its parasitoid.

    PubMed

    Gualtieri, Liberata; Nugnes, Francesco; Nappo, Anna G; Gebiola, Marco; Bernardo, Umberto

    2017-07-01

    The incidence of horizontal transmission as a route for spreading symbiont infections is still being debated, but a common view is that horizontal transfers require intimate between-species relationships. Here we study a system that meets ideal requirements for horizontal transmission: the gall wasp Leptocybe invasa and its parasitoid Quadrastichus mendeli (Hymenoptera: Eulophidae). These wasps belong to the same subfamily, spend most of their lives inside the same minute gall and are both infected by Rickettsia, a maternally inherited endosymbiotic bacteria that infects several arthropods, sometimes manipulating their reproduction, like inducing thelytokous parthenogenesis in L. invasa. Despite intimate contact, close phylogenetic relationship and the parasitoid's host specificity, we show that host and parasitoid do not share the same Rickettsia. We provide indirect evidence that Rickettsia infecting Q. mendeli may be inducing thelytokous parthenogenesis, as the symbiont is densely present in the reproductive apparatus and is vertically transmitted. Phylogenetic analyses based on 16S and gltA placed this symbiont in the leech group. The confirmed and presumed parthenogenesis-inducing Rickettsia discovered so far only infect eulophid wasps, and belong to three different groups, suggesting multiple independent evolution of the parthenogenesis inducing phenotype. We also show some degree of cospeciation between Rickettsia and their eulophid hosts. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  10. 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

  11. 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.

  12. Protection of 310l Stainless Steel from Wear at Elevated Temperatures using Conicraly Thermal Spray Coatings with and without Sic Addition

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Zhang, Tao; Li, Kaiyang; Li, Dongyang

    2017-10-01

    Due to its high oxidation resistance, 310L stainless steel is often used for thermal facilities working at high-temperatures. However, the steel may fail prematurely at elevated temperatures when encounter surface mechanical attacks such as wear. Thermal spray coatings have been demonstrated to be effective in protecting the steel from wear at elevated temperatures. In this study, we investigated the effectiveness of high velocity oxy-fuel(HVOF) spraying CoNiCrAlY/SiC coatings in resisting wear of 310L stainless steel at elevated temperature using a pin-on-disc wear tester. In order to further improve the performance of the coating, 5%SiC was added to the coating. It was demonstrated that the CoNiCrAlY/SiC coating after heat treatment markedly suppressed wear. However, the added SiC particles did not show benefits to the wear resistance of the coating. Microstructures of CoNiCrAlY coatings with and without the SiC addition were characterized in order to understand the mechanism responsible for the observed phenomena.

  13. Solenoid valve design minimizes vibration and sliding wear problem

    NASA Technical Reports Server (NTRS)

    Gillon, W. A., Jr.

    1968-01-01

    Two-way cryogenic solenoid valve resists damage from vibration and metallic interfacial sliding. The new system features a flat-faced armature guided by a flexure disk which eliminates sliding surfaces and is less subject to contamination and wear.

  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. 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.

  16. Type of motion and lubricant in wear simulation of polyethylene acetabular cup.

    PubMed

    Saikko, V; Ahlroos, T

    1999-01-01

    The wear of ultra-high molecular weight polyethylene, the most commonly used bearing material in prosthetic joints, is often substantial, posing a significant clinical problem. For a long time, there has been a need for simple but still realistic wear test devices for prosthetic joint materials. The wear factors produced by earlier reciprocating and unidirectionally rotating wear test devices for polyethylene are typically two orders of magnitude too low, both in water and in serum lubrication. Wear is negligible even under multidirectional motion in water. A twelve-station, circularly translating pin-on-disc (CTPOD) device and a modification of the established biaxial rocking motion hip joint simulator were built. With these simple and inexpensive devices, and with the established three-axis hip joint simulator, realistic wear simulation was achieved. This was due to serum lubrication and to the fact that the direction of sliding constantly changed relative to the polyethylene specimen. The type and magnitude of load was found to be less important. The CTPOD tests showed that the subsurface brittle region, which results from gamma irradiation sterilization of polyethylene in air, has poor wear resistance. Phospholipid and soy protein lubrication resulted in unrealistic wear. The introduction of devices like CTPOD may boost wear studies, rendering them feasible without heavy investment.

  17. Wear Distribution Detection of Knee Joint Prostheses by Means of 3D Optical Scanners

    PubMed Central

    Affatato, Saverio; Valigi, Maria Cristina; Logozzo, Silvia

    2017-01-01

    The objective of this study was to examine total knee polyethylene inserts from in vitro simulation to evaluate and display—using a 3D optical scanner—wear patterns and wear rates of inserts exposed to wear by means of simulators. Various sets of tibial inserts have been reconstructed by using optical scanners. With this in mind, the wear behavior of fixed and mobile bearing polyethylene knee configurations was investigated using a knee wear joint simulator. After the completion of the wear test, the polyethylene menisci were analyzed by an innovative 3D optical scanners in order to evaluate the 3D wear distribution on the prosthesis surface. This study implemented a new procedure for evaluating polyethylene bearings of joint prostheses obtained after in vitro wear tests and the proposed new approach allowed quantification of the contact zone on the geometry of total knee prostheses. The results of the present study showed that mobile TKPs (total knee prosthesis) have lower wear resistance with respect to fixed TKPs. PMID:28772725

  18. 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.

  19. Anodized porous titanium coated with Ni-CeO2 deposits for enhancing surface toughness and wear resistance

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaowei; Ouyang, Chun

    2017-05-01

    In order to make large improvements of surface toughness and wear resistance for pure titanium (Ti) substrate, anodic titanium oxide (ATO) surface with nanoporous structure was coated with the Ni-CeO2 nanocomposite coatings. Regarding TiO2 barrier layer on Ti surface to inhibit its electrochemical activity, pre-treatments were successively processed with anodizing, sensitizing, activating, and then followed by electroless Ni-P film to be acted as an activated layer for electroplating Ni-CeO2 deposits. The existing Pd atoms around ATO nanopores were expected as the heterogeneous nucleation sites for supporting the growing locations of electroless Ni-P film. The innovative of interface design using porous structure was introduced for bonding pinholes to achieve a metallurgical adhesion interface between Ti substrate and surface coatings. Besides the objectives of this work were to elucidate how effects by the adding CeO2 nanoparticles on modifying microstructures and wear mechanisms of Ni-CeO2 nanocomposite coatings. Many efforts of XRD, FE-SEM, TEM and Nanoindentation tests were devoted to comparing different wear behaviors of Ni-CeO2 coatings relative to pure nickel. Results indicated that uniform-distributed Ti nanopores with an average diameter size of ∼200 nm was achieved using the Phosphate-type anodizing solution at DC 150 V. A worn surface without fatigue cracks was observed for TAO surface coated with Ni-CeO2 deposits, showing the existing Ce-rich worn products to be acted as a solid lubricant phase for making a self-healing effect on de-lamination failures. More important, this finding will be the guidelines for Ce-rich precipitations to be expected as the strengthening phase in anodized porous of Ti, Al and Mg alloys for intensifying their surface properties.

  20. 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.

  1. Microstructure, Wear Resistance and Oxidation Behavior of Ni-Ti-Si Coatings Fabricated on Ti6Al4V by Laser Cladding.

    PubMed

    Zhuang, Qiaoqiao; Zhang, Peilei; Li, Mingchuan; Yan, Hua; Yu, Zhishui; Lu, Qinghua

    2017-10-30

    The Ni-Ti-Si composite coatings were successfully fabricated on Ti6Al4V by laser cladding. The microstructure were studied by SEM (scanning electron microscopy) and EDS (energy dispersive spectrometer). It has been found that Ti₂Ni and Ti₅Si₃ phases exist in all coatings, and some samples have TiSi₂ phases. Moreover, due to the existence of these phases, coatings presented relatively higher microhardness than that of the substrate (826 HV (Vickers hardness)) and the microhardness value of coating 3 is about twice larger than that of the substrate. During the dry sliding friction and wear test, due to the distribution of the relatively ductile phase of Ti₂Ni and reinforcement phases of Ti₅Si₃ and TiSi₂, the coatings performed good wear resistance. The oxidation process contains two stages: the rapid oxidation and slow oxidation by high temperature oxidation test at 800 °C for 50 h. Meanwhile, the value of the oxidation weight gain of the substrate is approximately three times larger than that of the coating 4. During the oxidation process, the oxidation film formed on the coating is mainly consisted of TiO₂, Al₂O₃ and SiO₂. Phases Ti₂Ni, Ti₅Si₃, TiSi₂ and TiSi were still found and it could be responsible for the improvement in oxidation resistance of the coatings by laser cladding.

  2. Wear-screening and joint simulation studies vs. materials selection and prosthesis design.

    PubMed

    Clarke, I C

    1982-01-01

    Satisfactory friction and wear performance of orthomedic biomaterials is an essential criterion for both hemiarthroplasty and total joint replacements. This report will chart the clinical historical experience of candidate biomaterials with their wear resistance and compare/contrast these data to experimental test predictions. The latter review will encompass publications dealing with both joint simulators and the more basic friction and wear screening devices. Special consideration will be given to the adequacy of the test protocol, the design of the experimental machines, and the accuracy of the measurement techniques. The discussion will then center on clinical reality vs. experimental adequacy and summarize current developments.

  3. Enhancing Fracture and Wear Resistance of Dentures/Overdentures Utilizing Digital Technology: A Case Series Report.

    PubMed

    Afify, Ahmed; Haney, Stephan

    2016-08-01

    Since it was first introduced into the dental world, computer-aided design/computer-aided manufacturing (CAD/CAM) technology has improved dramatically in regards to both data acquisition and fabrication abilities. CAD/CAM is capable of providing well-fitting intra- and extraoral prostheses when sound guidelines are followed. As CAD/CAM technology encompasses both surgical and prosthetic dental applications as well as fixed and removable aspects, it could improve the average quality of dental prostheses compared with the results obtained by conventional manufacturing methods. The purpose of this article is to provide an introduction into the methods in which this technology may be used to enhance the wear and fracture resistance of dentures and overdentures. This article will also showcase two clinical reports in which CAD/CAM technology has been implemented. © 2016 by the American College of Prosthodontists.

  4. 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.

  5. Comparison of dry sliding wear and friction behavior of Al6061/SiC PMMC with Al6061 alloy

    NASA Astrophysics Data System (ADS)

    Murthy, A. G. Shankara; Mehta, N. K.; Kumar, Pradeep

    2018-04-01

    Dry sliding wear and friction behavior tests were conducted on Al6061 alloy and Al6061/SiC particle reinforced metal matrix composites (PMMCs) reinforced with fine particles of 5, 10 and 15 µm size having 5,7.5 and 10% weight content fabricated by stir-casting route. Cylindrical sample pins produced as per ASTM standard were tested for various parameters like SiC size, weight content, load and sliding distance affecting the wear rate or resistance and friction. Results indicated that Al6061/SiCp composites exhibited good wear resistance compared to Al6061 alloy for the tested parameters.

  6. 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.

  7. 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.

  8. Testing Optimal Foraging Theory Using Bird Predation on Goldenrod Galls

    ERIC Educational Resources Information Center

    Yahnke, Christopher J.

    2006-01-01

    All animals must make choices regarding what foods to eat, where to eat, and how much time to spend feeding. Optimal foraging theory explains these behaviors in terms of costs and benefits. This laboratory exercise focuses on optimal foraging theory by investigating the winter feeding behavior of birds on the goldenrod gall fly by comparing…

  9. In vitro wear of Ionofil Molar AC quick glass-ionomer cement.

    PubMed

    Abesi, Farida; Safarcherati, Hengameh; Sadati, Javad; Kheirollahi, Hossein

    2011-01-01

    The aim of this study was to evaluate the three-body wear-resistance of one type of restorative glass-ionomer cement (GIC). Specimen including conventional GIC (Ionofil Molar AC Quick: IMACQ), hybrid ionomer (Fuji II LC), and composite resin (Heliomolar) were tested in a wearing machine. In this machine, a 6 kg load was applied via pressable chromium-cobalt bar at 5,000, 10,000, 20,000, 40,000, 80,000, 120,000 cycles. Specimen weight was measured by an electronical weight balance before and after each cycle. Data were analyzed using one-way analysis of variance (ANOVA) followed by a t-test, and a paired t-test at P≤0.05. The highest weight loss has been found in Fuji II LC, then in GIC IMACQ and the least wear rate has been reported in heliomolar composite in all cycles except 120,000 cycles. In 120,000 cycles, the highest weight loss was seen in GIC IMACQ, then Fuji II LC, and finally heliomolar composite. There was a statistically significant difference in weight loss between GIC IMACQ and heliomolar composite (P=0/001). The wear rate of GIC IMACQ was between those of heliomolar composite and Fuji II LC glass ionomer in all cycles except 120,000 cycles. The most important advantage of this new-generation glass ionomer is its good manipulability and also high wear-resistance compared to the hybrid ionomer. Therefore, it is suggested that it can be used as restorative material in class I restorations in primary teeth.

  10. Wear of seal materials used in aircraft propulsion systems

    NASA Technical Reports Server (NTRS)

    Bill, R. C.; Ludwig, L. P.

    1978-01-01

    The various types of seal locations in a gas turbine engine are described, and the significance of wear to each type is reviewed. Starting with positive contact shaft seals, existing material selection guidelines are reviewed, and the existing PV (contact pressure X sliding velocity) criteria for selecting seal materials are discussed, along with the theoretical background for these criteria. Examples of wear mechanisms observed to operate in positive contact seals are shown. Design features that can extend the operating capabilities of positive contact seals, including pressure balancing and incorporation of hydrodynamic lift are briefly discussed. It is concluded that, despite the benefits arising from these design features, improved positive contact seal materials from the standpoint of wear, erosion and oxidation resistance will be necessary for further improvements in seal performance and durability, and to meet stringent future challenges.

  11. 77 FR 14446 - Changes to the Generic Aging Lessons Learned (GALL) Report Revision 2 AMP XI.M41, “Buried and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-09

    ... NUCLEAR REGULATORY COMMISSION [NRC-2012-0055] Changes to the Generic Aging Lessons Learned (GALL... Aging Lessons Learned (GALL) Report,'' and the NRC staff's aging management review procedure and... into ADAMS. II. Background The NRC issues LR-ISGs to communicate insights and lessons learned and to...

  12. 77 FR 21813 - Changes to the Generic Aging Lessons Learned (GALL) Report Revision 2 AMP XI.M41, “Buried and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-11

    ... NUCLEAR REGULATORY COMMISSION [NRC-2012-0055] Changes to the Generic Aging Lessons Learned (GALL) Report Revision 2 AMP XI.M41, ``Buried and Underground Piping and Tanks'' AGENCY: Nuclear Regulatory... NUREG-1801, Revision 2, ``Generic Aging Lessons Learned (GALL) Report,'' and the NRC staff's aging...

  13. 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.

  14. 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

  15. Influence of filler loading on the two-body wear of a dental composite.

    PubMed

    Hu, X; Marquis, P M; Shortall, A C

    2003-07-01

    The purpose of the study was to explore the fundamental wear behaviour of a dental composite with different filler loadings under two-body wear conditions. The parent resin and filler components were mixed according to different weight ratios to produce experimental composites with filler loadings ranging from 20 to 87.5% by weight. A two-body wear test was conducted on the experimental composites using a wear-testing machine. The machine was designed to simulate the impact of the direct cyclic masticatory loading that occurs in the occlusal contact area in vivo. The results showed that there was little increase in the rate of wear with filler loadings below 60 wt%, but a sharp increase between 80 and 87.5 wt% in filler loading. Wide striations and bulk loss of material were apparent on the wear surfaces at higher filler loadings. Coefficients of friction increased with filler loading and followed the increase in rate of wear loss closely. It was concluded that, under two-body wear conditions, addition of high levels of filler particles into the resin matrix could reduce the wear resistance of dental composites. This finding may help when designing future dental composites for use in particular clinical settings.

  16. Increasing Wear Resistance of Titanium Alloys by Anode Plasma Electrolytic Saturation with Interstitial Elements

    NASA Astrophysics Data System (ADS)

    Belkin, P. N.; Kusmanov, S. A.; Dyakov, I. G.; Silkin, S. A.; Smirnov, A. A.

    2017-05-01

    In our previous studies, we have shown that anode plasma electrolytic saturation of titanium alloys with nitrogen and carbon can improve their tribological properties. Obtained structure containing oxide layer and solid solution of diffused element in titanium promotes the enhancement of running-in ability and the decrease in the wear rate in some special cases. In this paper, further investigations are reported regarding the tribological properties of alpha- and beta-titanium alloys in wear test against hardened steel (50 HRC) disk using pin-on-disk geometry and balls of Al2O3 (6.25 mm in diameter) or bearing steel (9.6 mm in diameter) with ball-on-plate one and normal load from 5 to 209 N. Reproducible results were obtained under testing samples treated by means of the plasma electrolytic nitriding (PEN) with the mechanical removal of the oxide layer. Friction coefficient of nitrided samples is 0.5-0.9 which is somewhat higher than that for untreated one (0.48-0.75) during dry sliding against Al2O3 ball. An increase in the sliding speed results in the polishing of nitrided samples and reduction of their wear rate by 60 times. This result is obtained for 5 min at 850 °C using PEN in electrolyte containing 5 wt.% ammonia and 10 wt.% ammonium chloride followed by quenching in solution. Optical microscope was employed to assist in the evaluation of the wear behavior. Sizes of wear tracks were measured by profilometer TR200.

  17. Surface Modification by Friction Stir Processing of Low-Carbon Steel: Microstructure Investigation and Wear Performance

    NASA Astrophysics Data System (ADS)

    Sattari, Behnoosh; Shamanian, Morteza; Salimijazi, Farshid; Salehi, Mehdi

    2018-02-01

    A low-carbon steel sheet with a thickness of 5 mm was subjected to friction stir processing (FSP) by one to four different passes. The microstructures of different regions were characterized using the optical microscopy and electron backscatter diffraction. The Vickers micro-harness was measured at the distance of 200 μm below the processed surfaces. The influence of pass numbers (PNs) on wear resistance was studied in terms of coefficients of friction (CoFs), weight losses and wear rates. SEM topographies of the worn surfaces were also studied to evaluate the wear mechanisms. Microstructure observations showed that Widmänstatten ferrite plates were formed in stir zones (SZs) and heat affected zones. As PN increased, these grains were widened due to the increment of the carbon diffusivity and lengthened because of the high heat input and microstructure anisotropy. Besides, increasing the PN causes increasing of the hardness and wear resistance, simultaneously. Specifically, the wear rate in the SZ was reduced from 2.8 × 10-2 mm3 m-1 in base metal to 0.3 × 10-2 mm3 m-1 in sample which was subjected to 4 FSP passes. However, variation in PN had no considerable effect on CoFs. Oxidative wear mechanism was observed on the worn surface of the steel and the FSPed samples while more debris was formed by increasing the PNs.

  18. Assessment of wear dependence parameters in complex model of cutting tool wear

    NASA Astrophysics Data System (ADS)

    Antsev, A. V.; Pasko, N. I.; Antseva, N. V.

    2018-03-01

    This paper addresses wear dependence of the generic efficient life period of cutting tools taken as an aggregate of the law of tool wear rate distribution and dependence of parameters of this law's on the cutting mode, factoring in the random factor as exemplified by the complex model of wear. The complex model of wear takes into account the variance of cutting properties within one batch of tools, variance in machinability within one batch of workpieces, and the stochastic nature of the wear process itself. A technique of assessment of wear dependence parameters in a complex model of cutting tool wear is provided. The technique is supported by a numerical example.

  19. 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

  20. Micro-wear features on unique 100-Mrad cups: two retrieved cups compared to hip simulator wear study.

    PubMed

    Yamamoto, Kengo; Masaoka, Toshinori; Manaka, Masakazu; Oonishi, Hironobu; Clarke, Ian; Shoji, Hiromu; Kawanabe, Keiichi; Imakiire, Atsuhiro

    2004-04-01

    We studied the micro-wear phenomena of unique, extensively cross-linked polyethylene cups (cross-linked with 1,000 kGy-irradiation) that had been used briefly in Japan. Two retrievals (at 15 years) came from the Japanese "SOM" hip system (implanted 1971-78). These were compared to a set of 0 kGy and 500-1,500 kGy cups run in our hip simulator. The polyethylene cups that had not been cross-linked had the greatest wear. The worn areas had a burnished appearance and were clearly separated from the unworn region by a distinct ridge-line. The worn areas had lost all machine tracks, showed a large amount of UHMWPE 'flow', and long PE fibrils. The associated surface rippling was degraded. These features were considered synonymous with severe polyethylene wear. In contrast, the worn areas in the very cross-linked cups had a visibly matte surface and no ridge-line. Micro-examination showed that the machine tracks were still present. Ripple formations were less obvious than in the cups that were not cross-linked, polyethylene surface fibrils were scarcer and all the fibrils were much smaller than in the cups that were not crosslinked. Our two retrieved cups and the simulator cups confirmed the greater wear-resistance of very cross-linked polyethylene. It should also be noted that the SOM cup design and processing were unique and differed greatly from that of modern polyethylene cups.

  1. A Novel Method to Assess Wear Rates of Retrieved Tibial Inserts Following in-vivo Use

    NASA Astrophysics Data System (ADS)

    Paniogue, Tanille J.

    Ultra-high molecular weight polyethylene (UHMWPE) on cobalt chrome is the bearing couple of choice for total knee arthroplasty. The number of patients undergoing total knee arthroplasty has been steadily growing and is projected to continue increasing rapidly in the near future. Many of these patients are younger and more active and therefore need a longer lasting device. However, many of these devices fail prematurely and often the primary reason for failure and ultimately revision is due to wear related issues. Therefore, examining how wear rates of the UHMWPE tibial insert change during in-vivo use can help elucidate the mechanisms of accelerated wear and hopefully aid in finding solutions to combat wear related failures. Different crosslinking treatments have been employed by manufacturers to improve wear resistance of the polyethylene. While this has been shown to be an effective way to reduce wear, crosslinking has led to other issues such as oxidative instability and a decline in mechanical properties. The purpose of this body of work is to examine how changes in oxidation, after in-vivo use, affect wear resistance. A novel testing method was developed to test the native articular surface from retrieved tibial inserts in a laboratory Pin-on-Disk (POD) simulator. The method was validated using short-duration implant articular surfaces and non-articular control pins. In the absence of high surface oxidation or severe surface damage, the articular surface pins had comparable steady state wear rates to their bulk counterparts. Tests of devices with longer in-vivo service show chemical changes consistent with a free-radical mediated oxidation mechanism. Tribological assessment of the articular surfaces shows increasing wear rates as a function of oxidation. While this relationship has been hypothesized in the literature, these experiments represent the first physical demonstration of the phenomenon. The wear mechanism is further explored through infrared

  2. Non-Magnetic, Tough, Corrosion- and Wear-Resistant Knives From Bulk Metallic Glasses and Composites

    NASA Technical Reports Server (NTRS)

    Hoffman, Douglas C.; Potter, Benjamin

    2013-01-01

    Quality knives are typically fabricated from high-strength steel alloys. Depending on the application, there are different requirements for mechanical and physical properties that cause problems for steel alloys. For example, diver's knives are generally used in salt water, which causes rust in steel knives. Titanium diver's knives are a popular alternative due to their salt water corrosion resistance, but are too soft to maintain a sharp cutting edge. Steel knives are also magnetic, which is undesirable for military applications where the knives are used as a tactical tool for diffusing magnetic mines. Steel is also significantly denser than titanium (8 g/cu cm vs. 4.5 g/cu cm), which results in heavier knives for the same size. Steel is hard and wear-resistant, compared with titanium, and can keep a sharp edge during service. A major drawback of both steel and titanium knives is that they must be ground or machined into the final knife shape from a billet. Since most knives have a mirrored surface and a complex shape, manufacturing them is complex. It would be more desirable if the knife could be cast into a net or near-net shape in a single step. The solution to the deficiencies of titanium, steel, and ceramic knives is to fabricate them using bulk metallic glasses (or composites). These alloys can be cast into net or near-net shaped knives with a combination of properties that exceed both titanium and steel. A commercially viable BMG (bulk metallic glass) or composite knife is one that exhibits one or all of the following properties: It is based on titanium, has a self-sharpening edge, can retain an edge during service, is hard, is non-magnetic, is corrosion-resistant against a variety of corrosive environments, is tough (to allow for prying), can be cast into a net-shape with a mirror finish and a complex shape, has excellent wear resistance, and is low-density. These properties can be achieved in BMG and composites through alloy chemistry and processing. For

  3. 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.

  4. Friction and wear of sintered fiber-metal abradable seal materials

    NASA Technical Reports Server (NTRS)

    Bill, R. C.; Shiembob, L. T.

    1977-01-01

    Three abradable gas path seal material systems based on a sintered NiCrAlY fibermetal structure were evaluated under a range of wear conditions representative of those likely to be encountered in various knife-edge seal (labyrinth or shrouded turbine) applications. Conditions leading to undesirable wear of the rotating knife were identified and a model was proposed based on thermal effects arising under different rub conditions. It was found, and predicted by the model, that low incursion (plunge) rates tended to promote smearing of the low density sintered material with consequent wear to the knife-edge. Tradeoffs benefits between baseline 19 percent dense material, a similar material of increased density, and a self lubricating coating applied to the 19 percent material were identified based on relative rub tolerance and erosion resistance.

  5. 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.

  6. Microstructure, Wear Resistance and Oxidation Behavior of Ni-Ti-Si Coatings Fabricated on Ti6Al4V by Laser Cladding

    PubMed Central

    Zhuang, Qiaoqiao; Zhang, Peilei; Li, Mingchuan; Yan, Hua; Yu, Zhishui; Lu, Qinghua

    2017-01-01

    The Ni-Ti-Si composite coatings were successfully fabricated on Ti6Al4V by laser cladding. The microstructure were studied by SEM (scanning electron microscopy) and EDS (energy dispersive spectrometer). It has been found that Ti2Ni and Ti5Si3 phases exist in all coatings, and some samples have TiSi2 phases. Moreover, due to the existence of these phases, coatings presented relatively higher microhardness than that of the substrate (826 HV (Vickers hardness)) and the microhardness value of coating 3 is about twice larger than that of the substrate. During the dry sliding friction and wear test, due to the distribution of the relatively ductile phase of Ti2Ni and reinforcement phases of Ti5Si3 and TiSi2, the coatings performed good wear resistance. The oxidation process contains two stages: the rapid oxidation and slow oxidation by high temperature oxidation test at 800 °C for 50 h. Meanwhile, the value of the oxidation weight gain of the substrate is approximately three times larger than that of the coating 4. During the oxidation process, the oxidation film formed on the coating is mainly consisted of TiO2, Al2O3 and SiO2. Phases Ti2Ni, Ti5Si3, TiSi2 and TiSi were still found and it could be responsible for the improvement in oxidation resistance of the coatings by laser cladding. PMID:29084174

  7. Laboratory evaluation of molluscicidal activity of extracts from Cotula cinerea (L) and Quercus lusitania var. infectoria galls (Oliv.).

    PubMed

    Redwane, A; Markouk, M; Lazrek, H B; Amarouch, H; Jana, M

    1998-01-01

    In this work, we have studied the molluscicidal activity of different extracts obtained from Cotula cinerea and Quercus lusitania var. infectoria galls. The hydroalcoholic extract of Cotula cinerea, acetonic extract and gallotanin of Quercus infectoria galls have presented high activity against Bulinus truncatus. The hydroalcoholic extract of Cotula cinerea was fractionated by chromatography on silica gel column. We have isolated two very active fractions at concentrations respectively of 52.5 and 27.5 ppm.

  8. Wear resistance evaluation of palm fatty acid distillate using four-ball tribotester

    NASA Astrophysics Data System (ADS)

    Golshokouh, Iman; Ani, Farid Nasir; Syahrullail, S.

    2012-06-01

    Petroleum reserves are declining nowadays while ironically petroleum is a major source of pollution despite many uses. Researchers are in effort to find an alternative to replace petroleum as a lubricant. One of the best replace sources for petroleum is bio-oil. In this paper, a comparative study of friction and wear was carried out using a fourball tester. In this research, Palm Fatty Acid Distillate (PFAD) and Jatropha oil, two well-known oils from the vegetable family oils were compared with Hydraulic mineral oil and commercial mineral Engine oil. All investigated oils in this study are used in industries as lubricants. PFAD is a product from refined crude palm oil. It exists as a light brown solid at room temperature and Jatropa oil is produced from the seeds of the Jatropha cruces, a plant that grows in marginal lands. For the wear test, the experimental research condition was comparing four kind of oils with ASTM condition in which the load applied was 392N. The sliding speed was 1200rpm under the lubricant temperature of 75 degree Celsius. The experiment was run for 3600 seconds. The experimental results demonstrated that the PFAD and Jatropha oils exhibited better performance in term of friction and wear compared to Hydraulic and Engine mineral oils.

  9. Wear Mechanism Maps for Magnesium Alloy AM60 and Composite AM60-9% (Al2O3)f

    NASA Astrophysics Data System (ADS)

    Ullah Khan, Muhammad Zafar

    The purpose of this work was to study the tribological behaviour of squeeze cast Mg alloy AM60 and its composite AM60-9% (Al2O3) f. Dry sliding wear tests were performed on specimens of these materials using a block-on-ring tribometer which was equipped with a COF and temperature measurement system. Wear, COF and temperature maps were constructed to illustrate the effect of temperature and COF on the wear behaviour of the Mg alloy and it's composite. Four wear regimes namely low, mild, transient and severe wear were identified. The transition from mild to severe wear regime was found to be dependent on the bulk temperature of the specimen. Oxidational wear prevailed in low and mild wear whereas plastic deformation induced wear and melt wear controlled the wear rates in transient and severe wear regimes, respectively. This study shows that the incorporation of Al2O3 fibres in AM60 alloy improved the wear resistance of the resulting composite by delaying the transition from mild to severe wear.

  10. Macro- and microtopographical examination and quantification of CAD-CAM composite resin 2- and 3-body wear.

    PubMed

    Stöckl, Carolin; Hampe, Rüdiger; Stawarczyk, Bogna; Haerst, Miriam; Roos, Malgorzata

    2018-04-05

    The selection of an appropriate restorative material based on wear behavior is important for the long-term success of a dental restoration. For computer-aided design and computer-aided manufacturing (CAD-CAM) composite resins, information about their wear resistance and wear mechanism is scarce. The purpose of this in vitro study was to compare the 2- and 3-body wear of CAD-CAM composite resins with that of lithium disilicate ceramic and to develop analysis software. Flat specimens were prepared from the following CAD-CAM composite resins: Cerasmart (CS), SHOFU Block HC (SH), Katana Avencia (KA), Brilliant Crios (BC), an experimental composite resin (EXP), and lithium disilicate ceramic IPS e.max CAD (REF). The specimens underwent 2-body wear (50 N, 5/55°C, 400 000 cycles) opposed by human enamel antagonists. Specimen wheels were prepared with each material on each wheel for 3-body wear with a millet slurry (15 N, 15% slip, 200 000 cycles). All specimens were digitized by using a dedicated laser scanner. Analysis software was developed to calculate macrotopographical examination of volume loss. The microtopography of the surfaces was examined by using scanning electron microscopy. For data analysis, the Kruskal-Wallis test with the Tukey-Kramer post hoc test and the 1-sample Wilcoxon test were used (α=.05). After 2-body wear simulation, SH and KA presented higher volume loss than the other CAD-CAM materials. For 3-body wear, REF had lower volume loss than CS, SH, or BC. In addition, BC led to higher volume loss than EXP. The patterns of 2- and 3-body wear were different. The ceramic showed good global wear resistance. The volume loss of the CAD-CAM composite resins differed and depended on the material. The 2- and 3-body wear test methods tended to differ with regard to volume loss. Examination of the worn surfaces revealed different mechanisms acting in 2- and 3-body wear test. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry

  11. Wearing gloves in the hospital

    MedlinePlus

    Infection control - wearing gloves; Patient safety - wearing gloves; Personal protective equipment - wearing gloves; PPE - wearing gloves; Nosocomial infection - wearing gloves; Hospital acquired infection - wearing gloves

  12. Sequential radiation of unrelated organisms: the gall fly Eurosta solidaginis and the tumbling flower beetle Mordellistena convicta.

    PubMed

    Abrahamson, W G; Blair, C P; Eubanks, M D; Morehead, S A

    2003-09-01

    Host shifts and the formation of insect-host races are likely common processes in the speciation of herbivorous insects. The interactions of goldenrods Solidago (Compositae), the gall fly Eurosta solidaginis (Diptera: Tephritidae) and the beetle Mordellistena convicta (Coleoptera: Mordellidae) provide behavioural, ecological and genetic evidence of host races that may represent incipient species forming via sympatric speciation. We summarize evidence for Eurosta host races and show that M. convicta has radiated from goldenrod stems to Eurosta galls to form host-part races and, having exploited the galler's host shift, has begun to differentiate into host races within galls. Thus, host-race formation has occurred in two interacting, but unrelated organisms representing two trophic levels, resulting in 'sequential radiation' (escalation of biodiversity up the trophic system). Distributions of host races and their behavioural isolating mechanisms suggest sympatric differentiation. Such differentiation suggests host-race formation and subsequent speciation may be an important source of biodiversity.

  13. 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.

  14. Western gall rust -- A threat to Pinus radiata in New Zealand

    Treesearch

    Tod D. Ramsfield; Darren J. Kriticos; Detlev R. Vogler; Brian W. Geils

    2007-01-01

    Western gall rust (Peridermium harknessii J. P. Moore (syn. Endocronartium harknessii (J. P. Moore) Y. Hiratsuka) is potentially a serious threat to exotic Pinus radiata D. Don plantations of New Zealand although the pathogen has not been recorded here. Mechanisms that may have prevented invasion of the pathogen include geographic...

  15. Wear behaviour and morphology of stir cast aluminium/SiC nanocomposites

    NASA Astrophysics Data System (ADS)

    Tanwir Alam, Md; Arif, Sajjad; Husain Ansari, Akhter

    2018-04-01

    Wear and friction play a vital role in the service life of components. Aluminium matrix nanocomposites possess tremendous potential for a number of applications in addition to their present uses. It is valuable to the field of newer materials for better performance in tribological applications. In this work, dry sliding wear, friction coefficient and morphology of aluminium alloy (A356) reinforced with silicon carbide nanoparticles (SiCn) were investigated. A356/SiCn nanocomposites (AMNCs) containing 1–5 weight percentage of SiCn were prepared through two-step stir casting process via mechanical ball milling. The wear test was conducted on pin-on-disc test apparatus. Regression analysis was performed to develop mathematical functions to fit the experimental data points. Morphological studies of Al and SiCn as-received, wear debris and worn surfaces were further analysed by SEM along with EDS. The occurrence of oxide layers was observed on worn surfaces. Iron trace was identified by wear debris. It was found that the wear loss and friction coefficient were strongly influenced by mechanical milling and SiCn content. The results exhibited that the friction coefficient reduces with the addition of SiCn as well as with the increase in load. However, wear resistance increases as the reinforcement content increases because of the embedding and wettability effects.

  16. Gall production on hawthorns caused by Gymnosporangium spp.in Hatay province, Turkey

    USDA-ARS?s Scientific Manuscript database

    Three hawthorn and related rust diseases caused by Gymnosporangium confusum on Crataegus monogyna, G. clavariiforme on C. orientalis, and G. sabinae on Pyrus communis were detected in Hatay province, Turkey. Gymnosporangium confusum was also found causing telial galls on Juniperus communis. Gymnospo...

  17. Historical account on gaining insights on the mechanism of crown gall tumorigenesis induced by Agrobacterium tumefaciens

    PubMed Central

    Kado, Clarence I.

    2014-01-01

    The plant tumor disease known as crown gall was not called by that name until more recent times. Galls on plants were described by Malpighi (1679) who believed that these extraordinary growth are spontaneously produced. Agrobacterium was first isolated from tumors in 1897 by Fridiano Cavara in Napoli, Italy. After this bacterium was recognized to be the cause of crown gall disease, questions were raised on the mechanism by which it caused tumors on a variety of plants. Numerous very detailed studies led to the identification of Agrobacterium tumefaciens as the causal bacterium that cleverly transferred a genetic principle to plant host cells and integrated it into their chromosomes. Such studies have led to a variety of sophisticated mechanisms used by this organism to aid in its survival against competing microorganisms. Knowledge gained from these fundamental discoveries has opened many avenues for researchers to examine their primary organisms of study for similar mechanisms of pathogenesis in both plants and animals. These discoveries also advanced the genetic engineering of domesticated plants for improved food and fiber. PMID:25147542

  18. Evidence of Differences between the Communities of Arbuscular Mycorrhizal Fungi Colonizing Galls and Roots of Prunus persica Infected by the Root-Knot Nematode Meloidogyne incognita▿

    PubMed Central

    Alguacil, Maria del Mar; Torrecillas, Emma; Lozano, Zenaida; Roldán, Antonio

    2011-01-01

    Arbuscular mycorrhizal fungi (AMF) play important roles as plant protection agents, reducing or suppressing nematode colonization. However, it has never been investigated whether the galls produced in roots by nematode infection are colonized by AMF. This study tested whether galls produced by Meloidogyne incognita infection in Prunus persica roots are colonized by AMF. We also determined the changes in AMF composition and biodiversity mediated by infection with this root-knot nematode. DNA from galls and roots of plants infected by M. incognita and from roots of noninfected plants was extracted, amplified, cloned, and sequenced using AMF-specific primers. Phylogenetic analysis using the small-subunit (SSU) ribosomal DNA (rDNA) data set revealed 22 different AMF sequence types (17 Glomus sequence types, 3 Paraglomus sequence types, 1 Scutellospora sequence type, and 1 Acaulospora sequence type). The highest AMF diversity was found in uninfected roots, followed by infected roots and galls. This study indicates that the galls produced in P. persica roots due to infection with M. incognita were colonized extensively by a community of AMF, belonging to the families Paraglomeraceae and Glomeraceae, that was different from the community detected in roots. Although the function of the AMF in the galls is still unknown, we hypothesize that they act as protection agents against opportunistic pathogens. PMID:21984233

  19. Evidence of differences between the communities of arbuscular mycorrhizal fungi colonizing galls and roots of Prunus persica infected by the root-knot nematode Meloidogyne incognita.

    PubMed

    Alguacil, Maria del Mar; Torrecillas, Emma; Lozano, Zenaida; Roldán, Antonio

    2011-12-01

    Arbuscular mycorrhizal fungi (AMF) play important roles as plant protection agents, reducing or suppressing nematode colonization. However, it has never been investigated whether the galls produced in roots by nematode infection are colonized by AMF. This study tested whether galls produced by Meloidogyne incognita infection in Prunus persica roots are colonized by AMF. We also determined the changes in AMF composition and biodiversity mediated by infection with this root-knot nematode. DNA from galls and roots of plants infected by M. incognita and from roots of noninfected plants was extracted, amplified, cloned, and sequenced using AMF-specific primers. Phylogenetic analysis using the small-subunit (SSU) ribosomal DNA (rDNA) data set revealed 22 different AMF sequence types (17 Glomus sequence types, 3 Paraglomus sequence types, 1 Scutellospora sequence type, and 1 Acaulospora sequence type). The highest AMF diversity was found in uninfected roots, followed by infected roots and galls. This study indicates that the galls produced in P. persica roots due to infection with M. incognita were colonized extensively by a community of AMF, belonging to the families Paraglomeraceae and Glomeraceae, that was different from the community detected in roots. Although the function of the AMF in the galls is still unknown, we hypothesize that they act as protection agents against opportunistic pathogens.

  20. Plasma Electrolytic Oxidation (PEO) Coatings on an A356 Alloy for Improved Corrosion and Wear Resistance

    NASA Astrophysics Data System (ADS)

    Peng, Zhijing

    Plasma electrolytic oxidizing (PEO) is an advanced technique that has been used to deposit thick and hard ceramic coatings on aluminium (Al) alloys. This work was however to use the PEO process to produce thin ceramic oxide coatings on an A356 Al alloy for improving corrosion and wear resistance of the alloy. Effects of current density and treatment time on surface morphologies and thickness of the PEO coatings were investigated. The improvement of galvanic corrosion properties of the coated A356 alloy vs. steel and carbon fibre were evaluated in E85 fuel or NaCl environments. Tribological properties of the coatings were studied with comparison to the uncoated A356 substrate and other commercially-used engine bore materials. The research results indicated that the PEO coatings could have excellent tribological and corrosion properties for aluminium engine applications.

  1. Guidelines for design, installation, and maintenance of a waterproof wearing surface for timber bridge decks

    Treesearch

    Richard E. Weyers; Joseph R. Loferski; J. Daniel Dolan; John E. Haramis; Joseph H. Howard; Lola Hislop

    2001-01-01

    To enhance long-term timber bridge performance, timber material must be protected from moisture. Wearing surfaces made of asphalt pavement with and without a waterproof membrane have been used to provide protection from moisture on timber decks. This type of wearing surface also protects the deck from other damage while providing a smooth, skid-resistant surface....

  2. Sliding Wear Characteristics and Corrosion Behaviour of Selective Laser Melted 316L Stainless Steel

    NASA Astrophysics Data System (ADS)

    Sun, Y.; Moroz, A.; Alrbaey, K.

    2014-02-01

    Stainless steel is one of the most popular materials used for selective laser melting (SLM) processing to produce nearly fully dense components from 3D CAD models. The tribological and corrosion properties of stainless steel components are important in many engineering applications. In this work, the wear behaviour of SLM 316L stainless steel was investigated under dry sliding conditions, and the corrosion properties were measured electrochemically in a chloride containing solution. The results show that as compared to the standard bulk 316L steel, the SLM 316L steel exhibits deteriorated dry sliding wear resistance. The wear rate of SLM steel is dependent on the vol.% porosity in the steel and by obtaining full density it is possible achieve wear resistance similar to that of the standard bulk 316L steel. In the tested chloride containing solution, the general corrosion behaviour of the SLM steel is similar to that of the standard bulk 316L steel, but the SLM steel suffers from a reduced breakdown potential and is more susceptible to pitting corrosion. Efforts have been made to correlate the obtained results with porosity in the SLM steel.

  3. Corrosion and Wear Response of Oxide-Reinforced Nickel Composite Coatings

    NASA Astrophysics Data System (ADS)

    Tirlapur, Pradeep; Muniprakash, M.; Srivastava, Meenu

    2016-07-01

    Various grades of fuels are used in automobiles, as a result the engine components are continuously subjected to simultaneous action of corrosion and wear. Ni-SiC composite coating is the most widely investigated and commercialized wear-resistant coating in the automotive industry. However, this coating cannot be used at temperatures above 450 °C due to the tendency of SiC to react with Ni and form brittle silicides. An alternate approach is to use oxide-reinforced coatings. In the present study, zirconia, ZrO2 and, yttria-stabilized zirconia, YSZ-reinforced Ni composite coatings have been developed by electrodeposition method. It was observed from the microhardness studies that there is no significant difference in the values for Ni-SiC and Ni-ZrO2 coatings. The corrosion behavior was evaluated using polarization and electrochemical impedance studies. The studies showed that oxide particle-reinforced Ni coatings possessed better corrosion resistance due to their lower corrosion current density, I corr. Tribo-corrosion studies were carried out to understand the synergistic effect of wear and corrosion on the performance of Ni-based composite coatings in 0.5 M Na2SO4. Among various composite coatings, Ni-YSZ exhibited less material loss thereby showing better tribo-corrosion behavior.

  4. Effect of thermal oxidation on corrosion and corrosion-wear behaviour of a Ti-6Al-4V alloy.

    PubMed

    Güleryüz, Hasan; Cimenoğlu, Hüseyin

    2004-07-01

    In this study, comparative investigation of thermal oxidation treatment for Ti-6Al-4V was carried out to determine the optimum oxidation conditions for further evaluation of corrosion-wear performance. Characterization of modified surface layers was made by means of microscopic examinations, hardness measurements and X-ray diffraction analysis. Optimum oxidation condition was determined according to the results of accelerated corrosion tests made in 5m HCl solution The examined Ti-6Al-4V alloy exhibited excellent resistance to corrosion after oxidation at 600 degrees C for 60 h. This oxidation condition achieved 25 times higher wear resistance than the untreated alloy during reciprocating wear test conducted in a 0.9% NaCl solution.

  5. Evaluation of wild juglans species for crown gall resistance

    USDA-ARS?s Scientific Manuscript database

    During the 2009 USDA, ARS, National Clonal Germplasm Repository (NCGR) germplasm screening season, we examined a total of ~300 seedlings from "new" genotypes for their resistance to A. tumefaciens. This consisted of seedlings from 89 mother trees representing J. regia and its conspecific taxon, J. s...

  6. Effect of Deformation Mode on the Wear Behavior of NiTi Shape Memory Alloys

    NASA Astrophysics Data System (ADS)

    Yan, Lina; Liu, Yong

    2016-06-01

    Owing to good biocompatibility, good fatigue resistance, and excellent superelasticity, various types of bio-medical devices based on NiTi shape memory alloy (SMA) have been developed. Due to the complexity in deformation mode in service, for example NiTi implants, accurate assessment/prediction of the surface wear process is difficult. This study aims at providing a further insight into the effect of deformation mode on the wear behavior of NiTi SMA. In the present study, two types of wear testing modes were used, namely sliding wear mode and reciprocating wear mode, to investigate the effect of deformation mode on the wear behavior of NiTi SMA in both martensitic and austenitic states. It was found that, when in martensitic state and under high applied loads, sliding wear mode resulted in more surface damage as compared to that under reciprocating wear mode. When in austenitic state, although similar trends in the coefficient of friction were observed, the coefficient of friction and surface damage in general is less under reciprocating mode than under sliding mode. These observations were further discussed in terms of different deformation mechanisms involved in the wear tests, in particular, the reversibility of martensite variant reorientation and stress-induced phase transformation, respectively.

  7. Sliding friction and wear behaviors of surface-coated natural serpentine mineral powders as lubricant additive

    NASA Astrophysics Data System (ADS)

    Zhang, Baosen; Xu, Yi; Gao, Fei; Shi, Peijing; Xu, Binshi; Wu, Yixiong

    2011-01-01

    This work aims to investigate the friction and wear properties of surface-coated natural serpentine powders (SP) suspended in diesel engine oil using an Optimal SRV oscillating friction and wear tester. The worn surface was characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). Results indicated that the additives can improve the wear resistance and decrease friction coefficient of carbon steel friction couples. The 0.5 wt% content of serpentine powders is found most efficient in reducing friction and wear at the load of 50 N. The SEM and XPS analysis results demonstrate that a tribofilm forms on the worn surface, which is responsible for the decrease in friction and wear, mainly with iron oxides, silicon oxides, graphite and organic compounds.

  8. Hardface coating systems and methods for metal alloys and other materials for wear and corrosion resistant applications

    DOEpatents

    Seals, Roland D.

    2015-08-18

    The present disclosure relates generally to hardface coating systems and methods for metal alloys and other materials for wear and corrosion resistant applications. More specifically, the present disclosure relates to hardface coatings that include a network of titanium monoboride (TiB) needles or whiskers in a matrix, which are formed from titanium (Ti) and titanium diboride (TiB.sub.2) precursors by reactions enabled by the inherent energy provided by the process heat associated with coating deposition and, optionally, coating post-heat treatment. These hardface coatings are pyrophoric, thereby generating further reaction energy internally, and may be applied in a functionally graded manner. The hardface coatings may be deposited in the presence of a number of fluxing agents, beta stabilizers, densification aids, diffusional aids, and multimode particle size distributions to further enhance their performance characteristics.

  9. Nematodes from galls on Myrtaceae. VII. Fergusobia from 'leafy' leaf bud galls in Australia, with re-description of Fergusobia tumifaciens (Currie 1937) Wachek 1955 and descriptions of Fergusobia planchonianae n. sp. and Fergusobia viminalisae n. sp.

    PubMed

    Davies, Kerrie A; Ye, Weimin; Giblin-Davis, Robin M; Taylor, Gary S; Hodda, Mike; Thomas, W Kelley

    2014-08-26

    Fergusobia tumifaciens (Currie 1937) Wachek 1955, the type species for the genus Fergusobia, is re-described from specimens collected from 'leafy' leaf bud galls on Eucalyptus bridgesiana near Albury in New South Wales, Australia. It is morphologically characterized by the combination of an open C-shaped parthenogenetic female with a small broadly conoid tail, a C-shaped infective female with a bluntly rounded tail tip, and an arcuate to J-shaped male with angular spicules, not heavily sclerotised, and short to mid-length peloderan bursa. Two new species of Fergusobia, collected from 'leafy' leaf bud galls on, respectively, Eucalyptus planchoniana in Queensland, and E. viminalis in South Australia, Australia, are described. Fergusobia planchonianae Davies n. sp. is characterised by the combination of a C-shaped parthenogenetic female with a conoid tail, an arcuate infective female with an hemispherical tail tip, and an almost straight to arcuate to C-shaped male with an angular spicule, a long peloderan bursa and a narrow tail. Fergusobia viminalisae Davies n. sp. is characterised by the combination of an open C-shaped parthenogenetic female with a broadly conoid tail, a C-shaped infective female with a bluntly rounded tail tip, and an arcuate to J-shaped male with an angular (not heavily sclerotised) spicule and short to mid-length peloderan bursa. The shield morphologies of the fly larvae associated with the 'leafy' leaf bud galls and their possible relationships are outlined. Possible evolutionary relationships of the Fergusobia nematodes from these galls are discussed, considering their morphology, DNA sequences, and the relationships of the associated Fergusonina flies and host plants. 

  10. Functionally gradient hard carbon composites for improved adhesion and wear

    NASA Astrophysics Data System (ADS)

    Narayan, Roger Jagdish

    A new approach is proposed for fabricating biomedical devices that last longer and are more biocompatible than those presently available. In this approach, a bulk material is chosen that has desirable mechanical properties (low modulus, high strength, high ductility and high fatigue strength). This material is coated with corrosion-resistant, wear-resistant, hard, and biocompatible hard carbon films. One of the many forms of carbon, tetrahedral amorphous carbon, consists mainly of sp3-bonded atoms. Tetrahedral amorphous carbon possesses properties close to diamond in terms of hardness, atomic smoothness, and inertness. Tetrahedral amorphous carbon and diamond films usually contain large amounts of compressive and sometimes tensile stresses; adhesive failure from these stresses has limited widespread use of these materials. This research involves processing, characterization and modeling of functionally gradient tetrahedral amorphous carbon and diamond composite films on metals (cobalt-chromium and titanium alloys) and polymers (polymethylmethacrylate and polyethylene) used in biomedical applications. Multilayer discontinuous thin films of titanium carbide, titanium nitride, aluminum nitride, and tungsten carbide have been developed to control stresses and graphitization in diamond films. A morphology of randomly interconnected micron sized diamond crystallites provides increased toughness and stress reduction. Internal stresses in tetrahedral amorphous carbon were reduced via incorporation of carbide forming elements (silicon and titanium) and noncarbide forming elements (copper, platinum, and silver). These materials were produced using a novel target design during pulsed laser deposition. These alloying atoms reduce hardness and sp3-bonded carbon content, but increase adhesion and wear resistance. Silver and platinum provide the films with antimicrobial properties, and silicon provides bioactivity and aids bone formation. Bilayer coatings were created that couple

  11. Dynamic SEM wear studies of tungsten carbide cermets. [friction and wear experiments

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined, and etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the tungsten carbide (WC) and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation, and the wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation, and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  12. Corrosion and wear properties of laser surface modified NiTi with Mo and ZrO 2

    NASA Astrophysics Data System (ADS)

    Ng, K. W.; Man, H. C.; Yue, T. M.

    2008-08-01

    Because of its biocompatibility, superelasticity and shape memory characteristics, NiTi alloys have been gaining immense interest in the medical field. However, there is still concern on the corrosion resistance of this alloy if it is going to be implanted in the human body for a long time. Titanium is not toxic but nickel is carcinogenic and is implicated in various reactions including allergic response and degeneration of muscle tissue. Debris from wear and the subsequent release of Ni + ions due to corrosion in the body system are fatal issues for long-term application of this alloy in the human body. This paper reports the corrosion and wear properties of laser surface modified NiTi using Mo and ZrO 2 as surface alloying elements, respectively. The modified layers which are free from microcracks and porosity, act as both physical barrier to nickel release and enhance the bulk properties, such as hardness, wear resistance, and corrosion resistance. The electrochemical performance of the surface modified alloy was studied in Hanks' solution. Electrochemical impedance spectroscopy was measured.

  13. 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.

  14. Effect of medium on friction and wear properties of compacted graphite cast iron processed by biomimetic coupling laser remelting process

    NASA Astrophysics Data System (ADS)

    Guo, Qing-chun; Zhou, Hong; Wang, Cheng-tao; Zhang, Wei; Lin, Peng-yu; Sun, Na; Ren, Luquan

    2009-04-01

    Stimulated by the cuticles of soil animals, an attempt to improve the wear resistance of compact graphite cast iron (CGI) with biomimetic units on the surface was made by using a biomimetic coupled laser remelting process in air and various thicknesses water film, respectively. The microstructures of biomimetic units were examined by scanning electron microscope and X-ray diffraction was used to describe the microstructure and identify the phases in the melted zone. Microhardness was measured and the wear behaviors of biomimetic specimens as functions of different mediums as well as various water film thicknesses were investigated under dry sliding condition, respectively. The results indicated that the microstructure zones in the biomimetic specimens processed with water film are refined compared with that processed in air and had better wear resistance increased by 60%, the microhardness of biomimetic units has been improved significantly. The application of water film provided finer microstructures and much more regular grain shape in biomimetic units, which played a key role in improving the friction properties and wear resistance of CGI.

  15. Friction and Wear Properties of As-deposited and Carbon Ion-implanted Diamond Films

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1994-01-01

    Recent work on the friction and wear properties of as-deposited and carbon ion-implanted diamond films was reviewed. Diamond films were produced by the microwave plasma chemical vapor deposition (CVD) technique. Diamond films with various grain sizes and surface roughnesses were implanted with carbon ions at 60 ke V ion energy, resulting in a dose of 1.2310(exp 17) carbon ions/cm(exp 2). Various analytical techniques, including Raman spectroscopy, proton recoil analysis, Rutherford backscattering, transmission and scanning electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction, were utilized to characterize the diamond films. Sliding friction experiments were conducted with a polished natural diamond pin in contact with diamond films in the three environments: humid air (40 percent relative humidity), dry nitrogen (less than 1 percent relative humidity), and ultrahigh vacuum (10(exp -7) Pa). The CVD diamond films indeed have friction and were properties similar to those of natural diamond in the three environments. The as-deposited, fine-grain diamond films can be effectively used as self-lubricating, wear-resistant coatings that have low coefficients of friction (0.02 to 0.04) and low wear rates (10(exp -7) to 10(exp -8)mm(exp 3)/N-m) in both humid air and dry nitrogen. However, they have high coefficients of friction (1.5 to 1.7) and a high wear rate (10(exp -4)mm(exp 3/N-m) in ultrahigh vacuum. The carbon ion implanation produced a thin surficial layer (less than 0.1 micron thick) of amorphous, nondiamond carbon on the diamond films. In humid air and dry nitrogen, the ion-implanted, fine- and coarse-grain diamond films have a low coefficient of friction (around 0.1) and a low wear rate (10(exp -7)mm(exp 3/N-m). Even in ultrahigh vacuum, the presence of the nondiamond carbon layer reduced the coefficient of friction of fine-grain diamond films to 0.1 or lower and the wear rate to 10(exp -6)mm(exp 3)/N-m. Thus, the carbon ion-implanted, fine

  16. Tribology and Tool Wear of Hot Dip Galvanized Zinc Magnesium Alloys on Cold Rolled Steel Sheets

    NASA Astrophysics Data System (ADS)

    Raab, A. E.; Berger, E.; Freudenthaler, J.; Leomann, F.; Walch, C.

    2011-05-01

    Recently zinc based coatings on cold rolled steel with improved functionality in terms of forming and/or corrosion behaviour have been intensively investigated in the steel industry1,2,3. One of the most promising products are zinc magnesium alloys produced in hot dip galvanizing process. These coatings were already introduced in construction industry a few years ago1. With some modifications the improved properties of the coating are also interesting for automotive industry. In the present work the tribological potential of hot dip galvanized zinc magnesium coatings (HDG/ZM) produced at an industrial line under regular production, was studied in terms of sliding properties, adhesive and abrasive tool wear. First a short introduction into surface morphology of HDG/ZM will be given. For the tribological characterization of the material, which is the main topic of the contribution, different tests were performed on hot dip galvanised zinc magnesium material and results were compared with classic hot dip galvanized zinc coating (HDG/Z). The investigations are mainly based on the strip draw test which allows the determination of the friction coefficient directly by using a constant contact pressure. Deep drawing property was tested by forming model cups. The abrasive tool wear was tested using a standard test for material used in automotive industry. The adhesive tool wear was investigated by characterizing the coating material transferred to the tool in the strip draw test. All performed tests show an improved drawability of HDG/ZM compared to classical HDG/Z reference material. However the most promising difference between HDG/ZM and HDG/Z is that galling was found to be less for HDG/ZM than for HDG/Z. Therefore HDG/ZM is an interesting system not only with respect to corrosion protection but also in terms of tribology and provides clear advantages in formability.

  17. Tribology and Tool Wear of Hot Dip Galvanized Zinc Magnesium Alloys on Cold Rolled Steel Sheets

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

    Raab, A. E.; Berger, E.; Freudenthaler, J.

    Recently zinc based coatings on cold rolled steel with improved functionality in terms of forming and/or corrosion behaviour have been intensively investigated in the steel industry. One of the most promising products are zinc magnesium alloys produced in hot dip galvanizing process. These coatings were already introduced in construction industry a few years ago. With some modifications the improved properties of the coating are also interesting for automotive industry. In the present work the tribological potential of hot dip galvanized zinc magnesium coatings (HDG/ZM) produced at an industrial line under regular production, was studied in terms of sliding properties, adhesivemore » and abrasive tool wear.First a short introduction into surface morphology of HDG/ZM will be given. For the tribological characterization of the material, which is the main topic of the contribution, different tests were performed on hot dip galvanised zinc magnesium material and results were compared with classic hot dip galvanized zinc coating (HDG/Z). The investigations are mainly based on the strip draw test which allows the determination of the friction coefficient directly by using a constant contact pressure. Deep drawing property was tested by forming model cups. The abrasive tool wear was tested using a standard test for material used in automotive industry. The adhesive tool wear was investigated by characterizing the coating material transferred to the tool in the strip draw test.All performed tests show an improved drawability of HDG/ZM compared to classical HDG/Z reference material. However the most promising difference between HDG/ZM and HDG/Z is that galling was found to be less for HDG/ZM than for HDG/Z. Therefore HDG/ZM is an interesting system not only with respect to corrosion protection but also in terms of tribology and provides clear advantages in formability.« less

  18. A comparative study of progressive wear of four dental monolithic, veneered glass-ceramics.

    PubMed

    Zhang, Zhenzhen; Yi, Yuanping; Wang, Xuesong; Guo, Jiawen; Li, Ding; He, Lin; Zhang, Shaofeng

    2017-10-01

    This study evaluated the wear performance and wear mechanisms of four dental glass-ceramics, based on the microstructure and mechanical properties in the progressive wear process. Bar (N = 40, n = 10) and disk (N = 32, n = 8) specimens were prepared from (A) lithium disilicate glass-ceramic (LD), (B) leucite reinforced glass-ceramic (LEU), (C) feldspathic glass-ceramic (FEL), and (D) fluorapatite glass-ceramic (FLU). The bar specimens were tested for three-point flexural strength, hardness, fracture toughness and elastic modulus. The disk specimens paired with steatite antagonists were tested in a pin-on-disk tribometer with 10N up to 1000,000 wear cycles. The wear analysis of glass-ceramics was performed using a 3D profilometer after every 200,000 wear cycles. Wear loss of steatite antagonists was calculated by measuring the weight and density using sensitive balance and Archimedes' method. Wear morphologies and microstructures were analyzed by scanning electron microscopy (SEM). The crystalline phase compositions were determined using X-ray diffraction (XRD). One-way analysis of variance (ANOVA) was used to analyze the data. Multiple pair-wise comparison of means was performed by Tukey's post-hoc test. LD showed the highest fracture toughness, flexural strength, elastic modulus and crystallinity, followed by LEU and FEL, and FLU showed the lowest. However, the hardness of LD was lower than all the other three types of ceramics. For steatite antagonists, LD produced the least wear loss of antagonist, followed by LEU and FEL, and FLU had the most wear loss. For glass-ceramic materials, LD exhibited similar wear loss as LEU, but more than FLU and FEL did. Moreover, fracture occurred on the wear surface of FLU. In the progressive wear process, veneering porcelains showed better wear resistance but fluorapatite veneering porcelains appeared fracture surface. Monolithic lithium disilicate glass-ceramics with higher mechanical properties showed more wear loss, however

  19. First new world record of a gall midge from palms: a new species of Contarinia (Diptera: Cecidomyiidae) from Geonoma cuneata in Costa Rica

    USDA-ARS?s Scientific Manuscript database

    Contarinia geonomae Gagné, new species (Diptera: Cecidomyiidae), is described from galls found on the infructescences of Geonoma cuneata (Arecaceae) in Costa Rica. The galls are cylindrical in shape and develop concurrently with or instead of the spherical fruit. The larval chamber is located at the...

  20. Wear of carbide inserts with complex surface treatment when milling nickel alloy

    NASA Astrophysics Data System (ADS)

    Fedorov, Sergey; Swe, Min Htet; Kapitanov, Alexey; Egorov, Sergey

    2018-03-01

    One of the effective ways of strengthening hard alloys is the creating structure layers on their surface with the gradient distribution of physical and mechanical properties between the wear-resistant coating and the base material. The article discusses the influence of the near-surface layer which is modified by low-energy high-current electron-beam alloying and the upper anti-friction layer in a multi-component coating on the wear mechanism of the replaceable multifaceted plates in the dry milling of the difficult to machine nickel alloys.