Solid Lubrication Fundamentals and Applications. Chapter 2

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1998-01-01

This chapter describes powerful analytical techniques capable of sampling tribological surfaces and solid-film lubricants. Some of these techniques may also be used to determine the locus of failure in a bonded structure or coated substrate; such information is important when seeking improved adhesion between a solid-film lubricant and a substrate and when seeking improved performance and long life expectancy of solid lubricants. Many examples are given here and through-out the book on the nature and character of solid surfaces and their significance in lubrication, friction, and wear. The analytical techniques used include the late spectroscopic methods.

Investigation of Potential Thermal Processing Techniques for the Enhancement of PS300 High Temperature Solid Lubricant Coatings

NASA Technical Reports Server (NTRS)

Benoy, Patricia A.

2000-01-01

Contemporary trends in rotating machinery development have produced a continuous evolution towards ever increasing speeds and higher operating temperatures. This process has been particularly evident in aerospace and automotive applications such as turbochargers. The combination of high temperature and high speed has exceeded the capacity of mainstream liquid lubrication technology. The NASA Glenn Research Center has been at the forefront in developing innovative solid lubricants for the oil free protection of rotating machinery under these extreme environmental conditions. The most recent of these is the PS 300 series of plasma sprayed solid lubricant coatings. St Louis University and NASA Glenn Research Center entered into this cooperative agreement to investigate potential thermal processing techniques for the enhancement of the PS 304 solid lubricant.

Lubricant Coating Process

NASA Technical Reports Server (NTRS)

1989-01-01

"Peen Plating," a NASA developed process for applying molybdenum disulfide, is the key element of Techniblast Co.'s SURFGUARD process for applying high strength solid lubricants. The process requires two machines -- one for cleaning and one for coating. The cleaning step allows the coating to be bonded directly to the substrate to provide a better "anchor." The coating machine applies a half a micron thick coating. Then, a blast gun, using various pressures to vary peening intensities for different applications, fires high velocity "media" -- peening hammers -- ranging from plastic pellets to steel shot. Techniblast was assisted by Rural Enterprises, Inc. Coating service can be performed at either Techniblast's or a customer's facility.

A Systems Approach to the Solid Lubrication of Foil Air Bearings for Oil-Free Turbomachinery

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher; Zaldana, Antonio R.; Radil, Kevin C.

2002-01-01

Foil air bearings are self-acting hydrodynamic bearings which rely upon solid lubricants to reduce friction and minimize wear during sliding which occurs at start-up and shut-down when surface speeds are too low to allow the formation of a hydrodynamic air film. This solid lubrication is typically accomplished by coating the non-moving foil surface with a thin, soft polymeric film. The following paper introduces a systems approach in which the solid lubrication is provided by a combination of self lubricating shaft coatings coupled with various wear resistant and lubricating foil coatings. The use of multiple materials, each providing different functions is modeled after oil-lubricated hydrodynamic sleeve bearing technology which utilizes various coatings and surface treatments in conjunction with oil lubricants to achieve optimum performance. In this study, room temperature load capacity tests are performed on journal foil air bearings operating at 14,000 rpm. Different shaft and foil coating technologies such as plasma sprayed composites, ceramic, polymer and inorganic lubricant coatings are evaluated as foil bearing lubricants. The results indicate that bearing performance is improved through the individual use of the lubricants and treatments tested. Further, combining several solid lubricants together yielded synergistically better results than any material alone.

Thin Film Solid Lubricant Development

NASA Technical Reports Server (NTRS)

Benoy, Patricia A.

1997-01-01

Tribological coatings for high temperature sliding applications are addressed. A sputter-deposited bilayer coating of gold and chromium is investigated as a potential solid lubricant for protection of alumina substrates during sliding at high temperature. Evaluation of the tribological properties of alumina pins sliding against thin sputtered gold films on alumina substrates is presented.

Tribological composition optimization of chromium-carbide-based solid lubricant coatings for foil gas bearings at temperatures to 650 C

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher

1988-01-01

The determination of the tribilogically optimum composition of chromium-carbide-based solid lubricant coatings using a foil gas bearing test apparatus is described. The coatings contain a wear resistant chromium carbide `base stock' with the lubricant additives silver and BaF2-CaF2 eutectic. The coating composition is optimized for air-lubricated foil gas bearings at temperatures ranging from 25 to 650 C. The various compositions were prepared by powder blending, then plasma sprayed onto Inconel 718 test journals and diamond ground to the desired coating thickness and surface finish. The journals were operated against preoxidized Ni-Cr alloy foils, and the test bearings were subjected to repeated start-stop cycles under a bearing unit of 14 kPa. Sliding contact between the coated journal and the smooth foil occurs during bearing start-up before lift-off or hydrodynamic lubrication by the air film and during bearing coast-down. The bearings were tested for 9000 start-stop cycles or until specimen reached a predetermined failure level.

Industry Needs Fulfilled by Patented NASA PS300 Solid Lubricant Technology

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher

2003-01-01

In 1999, the NASA Glenn Research Center was awarded a patent (#5866518) for a new high-temperature solid lubricant coating material, PS300. A combination of wear-resistant metals and ceramics with solid lubricant additives, PS300 reduces friction and wear in sliding contacts from below ambient to over 650 C. This lubricant is an outgrowth of over three decades of high-temperature tribological research and was specifically developed as a shaft lubricant to protect foil air bearings used in Oil-Free turbomachinery, like gas turbines. Foil bearings are lubricated by air at high speeds but experience sliding and wear during initial startup and shut down when a lubricating film of air has not yet developed. PS300 shaft coatings have successfully lubricated foil bearings for over 100 000 cycles without wearing out.

Solid lubricants: A survey

NASA Technical Reports Server (NTRS)

Campbell, M. E.

1972-01-01

A survey is presented of the most recent developments and trends in the field of solid lubrication. Topics discussed include: a history of solid lubrication, lubricating solids, bonded lubricants, new developments, methods of evaluation, environmental effects, application methods, novel materials, and designs for the use of solid lubricants. Excerpts of solid lubricant specifications and a discussion of contact stresses imposed on specimens in three types of test machines used for the evaluation of solid lubricants are presented.

CVD method of forming self-lubricating composites

DOEpatents

Besmann, T.M.; Blau, P.J.; Lee, W.Y.; Bae, Y.W.

1998-12-01

An article having a multiphase composite lubricant coating of a hard refractory matrix phase of titanium nitride dispersed with particles of a solid lubricating phase of molybdenum disulfide is prepared by heating the article to temperatures between 350 and 850 C in a reaction vessel at a reduced pressure and passing a gaseous mixture of Ti((CH{sub 3}){sub 2}N){sub 4}, MoF{sub 6}, H{sub 2}S and NH{sub 3} over the heated article forming a multiphase composite lubricant coating on the article. 1 fig.

CVD method of forming self-lubricating composites

DOEpatents

Besmann, Theodore M.; Blau, Peter J.; Lee, Woo Y.; Bae, Yong W.

1998-01-01

An article having a multiphase composite lubricant coating of a hard refractory matrix phase of titanium nitride dispersed with particles of a solid lubricating phase of molybdenum disulfide is prepared by heating the article to temperatures between 350.degree. and 850.degree. C. in a reaction vessel at a reduced pressure and passing a gaseous mixture of Ti((CH.sub.3).sub.2 N).sub.4, MoF.sub.6, H.sub.2 S and NH.sub.3 over the heated article forming a multiphase composite lubricant coating on the article.

Lubrication with solids.

NASA Technical Reports Server (NTRS)

Buckley, D. H.; Johnson, R. L.

1972-01-01

Brief discussion of the historical background, variety range, chemistry, physics, and other properties of solid lubricants, and review of their current uses. The widespread use of solid lubricants did not occur until about 1947. At present, they are the object of such interest that a special international conference on their subject was held in 1971. They are used at temperatures beyond the useful range of conventional lubricating oils and greases. Their low volatility provides them with the capability of functioning effectively in vacuum and invites their use in space applications. Their high load carrying ability makes them useful with heavily loaded components. Solid lubricants, however, do lack some of the desirable properties of conventional lubricants. Unlike oils and greases, which have fluidity and can continuously be carried back into contact with lubricated surfaces, solid lubricants, because of their immobility, have finite lives. Also, oils and greases can carry away frictional heat from contacting surfaces, while solid lubricants cannot.

Transition of PS300 Solid Lubricant Coating Technology to Field Aided by Demonstration on Key Substrate Alloys

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher

2003-01-01

PS300 is a high-temperature solid lubricant coating originally developed to lubricate nickel-based superalloy shafts operating against foil air bearings in Oil-Free turbomachinery applications. PS300 is a plasma-spray-deposited coating developed at the NASA Glenn Research Center. It is available for non-exclusive licensing and has found applications in aerospace and industry. PS300 reduces friction and wear from below room temperature to over 650 C in both oxidizing and reducing environments. Early development centered on coating nickel-based shafts for use in turbomachinery. Potential industrial and aerospace customers, however, expressed interest in using the coating on a wide variety of substrates including steels, stainless steels, and nonferrous alloys like aluminum and titanium. To support this interest, a research program was carried out at Glenn in which nine different substrate candidate materials were evaluated for suitability with the PS300 coating. The materials were first coated with PS300 and then tested for coating strength and adhesion both before and after exposure to high-temperature air.

Solid lubricants

NASA Technical Reports Server (NTRS)

Sliney, Harold E.

1991-01-01

The state of knowledge of solid lubricants is reviewed. The results of research on solid lubricants from the 1940's to the present are presented from a historical perspective. Emphasis is placed largely, but not exclusively, on work performed at NASA Lewis Research Center with a natural focus on aerospace applications. However, because of the generic nature of the research, the information presented in this review is applicable to most areas where solid lubricant technology is useful.

Lubricating Properties of Lead-Monoxide-Base Coatings of Various Compositions at Temperatures to 1250 F

NASA Technical Reports Server (NTRS)

Sliney, Harold E.

1959-01-01

A number of ceramic coatings of different compositions containing lead monoxide (PbO) were studied to determine their relative merits as dry-film lubricants. Lead monoxide is known to be an effective solid lubricant at elevated temperatures, and this oxide was the main component in all compositions studied. Friction and wear properties were determined at temperatures from 750 to 1250 F, at a sliding velocity of 430 feet per minute, and at a normal load of 1 kilogram. In all of the coatings, PbO was the component primarily responsible for the lubricating properties. Oxides other than PbO had an indirect effect on lubrication by influencing such properties as adhesion, hardness, vitrifying or glaze-forming tendency, melting or softening point, and chemical stability of the coatings. Notable among these oxides were magnetite (Fe3O4.), which had generally a beneficial influence on ceramic- to-metal adhesion, and silica (SiO2), which inhibited the oxidation of PbO and enhanced the tendency for glaze formation on the sliding surfaces. Several of the compositions studied provided protection against metal-to-metal adhesive wear, galling, or seizure at test temperatures from 750 to 1250 F. Coating friction coefficients ranged from 0.20 to 0.37 at 75 F but were around 0.08 to 0.20 at temperatures of 1250 F.

A Review to the Laser Cladding of Self-Lubricating Composite Coatings

NASA Astrophysics Data System (ADS)

Quazi, M. M.; Fazal, M. A.; Haseeb, A. S. M. A.; Yusof, Farazila; Masjuki, H. H.; Arslan, A.

2016-06-01

Liquid lubricants are extremely viable in reducing wear damage and friction of mating components. However, due to the relentless pressure and the recent trend towards higher operating environments in advanced automotive and aerospace turbo-machineries, these lubricants cease to perform and hence, an alternate system is required for maintaining the self-lubricating environment. From the viewpoint of tribologist, wear is related to near-surface regions and hence, surface coatings are considered suitable for improving the functioning of tribo-pairs. Wear resistant coatings can be fabricated with the addition of various solid lubricants so as to reduce friction drag. In order to protect bulk substrates, self-lubricating wear resistant composite coatings have been fabricated by employing various surface coating techniques such as electrochemical process, physical and chemical vapor depositions, thermal and plasma spraying, laser cladding etc. Studies related to laser-based surface engineering approaches have remained vibrant and are recognized in altering the near surface regions. In this work, the latest developments in laser based self-lubricating composite coatings are highlighted. Furthermore, the effect of additives, laser processing parameters and their corresponding influence on mechanical and tribological performance is briefly reviewed.

Development of solid-lubricated ball-screws for use in space

NASA Technical Reports Server (NTRS)

Chiba, Masatoshi; Gyougi, Toru; Nishimura, Makoto; Seki, Katsumi

1991-01-01

Ball-screws lubricated by solid lubricant films containing molybdenum disulphide are developed. The ball-screws (shaft diameter: phi 25 mm, length: 667 mm) were operated under a load of 40 to 120 N at a speed of 1.5 to 200 rpm at 10(exp -5) Pa. First, ball-screws made of stainless steel SUS 440C were studied using test equipment originally designed for this study. To reduce weight, the next step taken was to develop a ball-screw made of 6Al-4V-titanium. Long wear-life of more than 1 x 10(exp 7) revolutions was achieved with solid lubricated ball-screws made of SUS 440C and 6Al-4V-titanium in a hard vacuum. According to the surface profile of the shaft measured after 1 x 10(exp 7) revolutions, more solid lubricant remained on the surface of 6Al-4V-titanium than that of stainless steel. Auger and EPMA analysis confirmed lubrication was maintained by solid lubricant on nuts and screws after the lubricant films on the balls were worn off.

Friction and Wear Characteristics of a Modified Composite Solid Lubricant Plasma Spray Coating

NASA Technical Reports Server (NTRS)

Stanford, M. K.; DellaCorte, C.

2004-01-01

LCR304 is a solid lubricant coating composed of Ni-10Cr, Cr2O3, BaF2-CaF2 and Ag and developed for dimensional stability in high temperature air. This coating is a modification of PS304, which differs in that the Ni-Cr constituent contains 20wt% Cr. The tribological characteristics of LCR304 were evaluated by pin-on-disk and foil air bearing rig testing from 25 to 650 C and compared to previous test results with PS304. For both tests, the friction coefficient decreased as temperature increased from 25 to 650 C. Wear generally decreased with increasing temperature for all pin-on-disk tests. LCR304 coated components produced the least wear of Inconel X-750 counterface materials at 427 and 650 C. These results indicate that the LCR304 coating has potential as a replacement for PS304 in, for example, low cycle (minimum wear) applications where dimensional stability is imperative.

Experimental test program for evaluation of solid lubricant coating as applied to compliant foil gas bearings to 315 deg C

NASA Technical Reports Server (NTRS)

Wagner, R. C.

1985-01-01

An experimental apparatus and test procedure was developed to compare the performance of two solid lubricant coatings for air lubricated compliant foil gas bearings in the temperature range of 25 to 315 C. Polyimide bonded additive (SBGC) were tested extensively for durability and frictional characteristics. A partial arc bearing constructed of Inconel X-750 was coated on the bore with one of these coatings. The foil was subjected to repeated start/stop cycles. Performance comparisons reveal that although both coatings survive thousands of start/stop cycles, only the PBGF coated bearing achieves the specified 9000 start/stops. There is enough wear on the SBGC coated bearing to warrant termination of the test prior to 9000 start/stop cycles due to coating failure. The frictional characteristics of the PBGF are better at the elevated temperatures than at lower temperatures; a marked increase in sliding friction occurs as the temperature decreases. The SBGC maintains relatively constant frictional characteristics independent of operating temperature.

Effects of silver and group II fluoride solid lubricant additions to plasma-sprayed chromium carbide coatings for foil gas bearings to 650 C

NASA Technical Reports Server (NTRS)

Wagner, R. C.; Sliney, Harold E.

1986-01-01

A new self-lubricating coating composition of nickel aluminide-bonded chromium carbide formulated with silver and Group II fluorides was developed in a research program on high temperature solid lubricants. One of the proposed applications for this new coating composition is as a wide temperature spectrum solid lubricant for complaint foil gas bearings. Friction and wear properties were obtained using a foil gas bearing start-stop apparatus at temperatures from 25 to 650 C. The journals were Inconel 748. Some were coated with the plasma sprayed experimental coating, others with unmodified nickel aluminide/chromium carbide as a baseline for comparison. The additional components were provided to assist in achieving low friction over the temperature range of interest. Uncoated, preoxidized Inconel X-750 foil bearings were operated against these surfaces. The foils were subjected to repeated start/stop cycles under a 14-kPa (2-Psi) bearing unit loading. Sliding contact occurred during lift-off and coastdown at surface velocities less than 6 m/s (3000 rPm). Testing continued until 9000 start/stop cycles were accumulated or until a rise in starting torque indicated the journal/bearing had failed. Comparison in coating performance as well as discussions of their properties and methods of application are given.

Synergistic effect between nano-ceramic lubricating additives and electroless deposited Ni-W-P coating

NASA Astrophysics Data System (ADS)

Chen, Min; Cheng, Wushan; Zhao, Zuxin; Huang, Xiaobo

2013-01-01

The major solving ways for the material wear are surface modification and lubrication. Currently, the researches at home and abroad are all limited to the single study of either nano-lubricating oil additive or electroless deposited coating. The surface coating has high hardness and high wear resistance, however, the friction reduction performance of the coating with high hardness is not good, the thickness of the coating is limited, and the coating can not regenerate after wearing. The nano-lubricating additives have good tribological performance and self-repair function, but under heavy load, the self-repair rate to the worn surface with the nano-additives is smaller than the wearing rate of the friction pair. To solve the above problems, the Ni-W-P alloy coating and deposition process with excellent anti-wear, and suitable for industrial application were developed, the optimum bath composition and process can be obtained by studying the influence of the bath composition, temperature and PH value to the deposition rate and the plating solution stability. The tribological properties as well as anti-wear and friction reduction mechanism of wear self-repair nano-ceramic lubricating additives are also studied. The ring-block abrasion testing machine and energy dispersive spectrometer are used to explore the internal relation between the coating and the nano-lubricating oil additives, and the tribology mechanism, to seek the synergetic effect between the two. The test results show that the wear resistance of Ni-W-P alloy coating (with heat treatment and in oil with nano-ceramic additives) has increased hundreds times than 45 steel as the metal substrate in basic oil, the friction reduction performance is improved. This research breaks through the bottleneck of previous separate research of the above-mentioned two methods, and explores the combination use of the two methods in industrial field.

NASA PS400: A New Temperature Solid Lubricant Coating for High Temperature Wear Applications

NASA Technical Reports Server (NTRS)

DellaCorte, C.; Edmonds, B. J.

2009-01-01

A new solid lubricant coating, NASA PS400, has been developed for high temperature tribological applications. This plasma sprayed coating is a variant of the patented PS304 coating and has been formulated to provide higher density, smoother surface finish and better dimensional stability than PS304. PS400 is comprised of a nickel-molybdenum binder that provides strength, creep resistance and extreme oxidative and dimensional stability. Chromium oxide, silver and barium-calcium fluoride eutectic are added to the binder to form PS400.Tribological properties were evaluated with a pin-on-disk test rig in sliding contact to 650 C. Coating material samples were exposed to air, argon and vacuum at 760 C followed by cross section microscopic analysis to assess microstructure stability. Oil-Free microturbine engine hot section foil bearing tests were undertaken to assess PS400 s suitability for hot foil gas bearing applications. The preliminary results indicate that PS400 exhibits tribological characteristics comparable to the PS304 coating but with enhanced creep resistance and dimensional stability suitable for demanding, dynamic applications.

Reactive Fabrication and Effect of NbC on Microstructure and Tribological Properties of CrS Co-Based Self-Lubricating Coatings by Laser Cladding

PubMed Central

Fang, Liuyang; Yan, Hua; Yao, Yansong; Zhang, Peilei; Gao, Qiushi; Qin, Yang

2017-01-01

The CrS/NbC Co-based self-lubricating composite coatings were successfully fabricated on Cr12MoV steel surface by laser clad Stellite 6, WS2, and NbC mixed powders. The phase composition, microstructure, and tribological properties of the coatings ware investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS), as well as dry sliding wear testing. Based on the experimental results, it was found reactions between WS2 and Co-based alloy powder had occurred, which generated solid-lubricant phase CrS, and NbC play a key role in improving CrS nuclear and refining microstructure of Co-based composite coating during laser cladding processing. The coatings were mainly composed of γ-Co, CrS, NbC, Cr23C6, and CoCx. Due to the distribution of the relatively hard phase of NbC and the solid lubricating phase CrS, the coatings had better wear resistance. Moreover, the suitable balance of CrS and NbC was favorable for further decreasing the friction and improving the stability of the contact surfaces between the WC ball and the coatings. The microhardness, friction coefficient, and wear rate of the coating 4 (Clad powders composed of 60 wt % Stellite 6, 30 wt % NbC and 10 wt % WS2) were 587.3 HV0.5, 0.426, and 5.61 × 10−5 mm3/N·m, respectively. PMID:29283411

Reactive Fabrication and Effect of NbC on Microstructure and Tribological Properties of CrS Co-Based Self-Lubricating Coatings by Laser Cladding.

PubMed

Fang, Liuyang; Yan, Hua; Yao, Yansong; Zhang, Peilei; Gao, Qiushi; Qin, Yang

2017-12-28

The CrS/NbC Co-based self-lubricating composite coatings were successfully fabricated on Cr12MoV steel surface by laser clad Stellite 6, WS₂, and NbC mixed powders. The phase composition, microstructure, and tribological properties of the coatings ware investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS), as well as dry sliding wear testing. Based on the experimental results, it was found reactions between WS₂ and Co-based alloy powder had occurred, which generated solid-lubricant phase CrS, and NbC play a key role in improving CrS nuclear and refining microstructure of Co-based composite coating during laser cladding processing. The coatings were mainly composed of γ-Co, CrS, NbC, Cr 23 C₆, and CoC x . Due to the distribution of the relatively hard phase of NbC and the solid lubricating phase CrS, the coatings had better wear resistance. Moreover, the suitable balance of CrS and NbC was favorable for further decreasing the friction and improving the stability of the contact surfaces between the WC ball and the coatings. The microhardness, friction coefficient, and wear rate of the coating 4 (Clad powders composed of 60 wt % Stellite 6, 30 wt % NbC and 10 wt % WS₂) were 587.3 HV 0.5 , 0.426, and 5.61 × 10 -5 mm³/N·m, respectively.

Lubrication handbook for the space industry. Part A: Solid lubricants. Part B: Liquid lubricants

NASA Technical Reports Server (NTRS)

Mcmurtrey, E. L.

1985-01-01

This handbook is intended to provide a ready reference for many of the solid and liquid lubricants used in the space industry. Lubricants and lubricant properties are arranged systematically so that designers, engineers, and maintenance personnel can conveniently locate data needed for their work. This handbook is divided into two major parts (A and B). Part A is a compilation of solid lubricant suppliers information on chemical and physical property of data of more than 250 solid lubricants, bonded solid lubricants, dispersions, and composites. Part B is a compilation of chemical and physical porperty data of more then 250 liquid lubricants, greases, oils, compounds, and fluids. The listed materials cover a broad spectrum from manufacturing and ground support to hardware applications of spacecraft.

Hard-on-hard lubrication in the artificial hip under dynamic loading conditions.

PubMed

Sonntag, Robert; Reinders, Jörn; Rieger, Johannes S; Heitzmann, Daniel W W; Kretzer, J Philippe

2013-01-01

The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal.

Hard-on-Hard Lubrication in the Artificial Hip under Dynamic Loading Conditions

PubMed Central

Sonntag, Robert; Reinders, Jörn; Rieger, Johannes S.; Heitzmann, Daniel W. W.; Kretzer, J. Philippe

2013-01-01

The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal. PMID:23940772

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.

Effects of heat treatment on microstructure and mechanical properties of Ni60/h-BN self-lubricating anti-wear composite coatings on 304 stainless steel by laser cladding

NASA Astrophysics Data System (ADS)

Lu, Xiao-Long; Liu, Xiu-Bo; Yu, Peng-Cheng; Zhai, Yong-Jie; Qiao, Shi-Jie; Wang, Ming-Di; Wang, Yong-Guang; Chen, Yao

2015-11-01

Laser clad Ni60/h-BN self-lubricating anti-wear composite coating on 304 stainless steel were heat treated at 600 °C (stress relief annealing) for 1 h and 2 h, respectively. Effects of the phase compositions, microstructure, microhardness, nano-indentation and tribological properties of the composite coatings with and without heat treatment had been investigated systemically. Results indicated that three coatings mainly consist of the matrix γ-(Ni, Fe) solid solution, the CrB ceramic phases and the h-BN lubricating phases. The maximum microhardness of the coatings was first increased from 667.7 HV0.5 to 765.0 HV0.5 after heat treatment for 1 h, and then decreased to 698.3 HV0.5 after heat treatment for 2 h. The hardness of γ-(Ni, Fe) solid solution without heat treatment and after heat treatment 1 h and 2 h were 5.09 GPa, 7.20 GPa and 3.77 GPa, respectively. Compared with the coating without heat treatment, the friction coefficients of the coating after heat treatment were decreased obviously. Effects of the heat treatment time on friction coefficient were negligible, but were significant on wear volume loss. Comparatively speaking, the laser clad self-lubricating anti-wear composite coating after heat treatment for 1 h presented the best anti-wear and friction reduction properties.

Thermal Effects on a Low Cr Modification of PS304 Solid Lubricant Coating

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.; Yanke, Anne M.; DellaCorte, Christopher

2004-01-01

PS304 is a high temperature composite solid lubricant coating composed of Ni-Cr, Cr2O3, BaF2-CaF2 and Ag. The effect of reducing chromium content on the formation of voids in the Ni-Cr particles after heat treatment in PS304 coating was investigated. Coatings were prepared with Ni-20Cr or Ni-10Cr powder and in various combinations with the other constituents of PS304 (i.e., chromia, silver and eutectic BaF2-CaF2 powders) and deposited on metal substrates by plasma spray. Specimens were exposed to 650 C for 24 hr or 1090 C for 15 hr and then examined for changes in thickness, coating microstructure and adhesion strength. Specimens with Ni-10Cr generally had less thickness increase than specimens with Ni-20Cr, but there was great variance in the data. Reduction of chromium concentration in Ni-Cr powder tended to reduce the appearance of voids in the Ni-Cr phase after heat exposure. The presence of BaF2-CaF2 resulted in a significant increase in coating adhesion strength after heat treatment, while coatings without BaF2-CaF2 had no significant change. Chemical composition analysis suggested that the void formation was due to oxidation of chromium in the Ni-Cr constituent.

Development and Implementation of Environmentally Compatible Solid Film Lubricants

NASA Technical Reports Server (NTRS)

Novak, Howard L.; Hall, Phillip B.

1999-01-01

Multi-body launch vehicles require the use of Solid Film Lubricants (SFLs) to allow for unrestricted relative motion between structural assemblies and components during lift-off and ascent into orbit. The Space Shuttle Solid Rocket Booster (SRB), uses a dual coat, ceramic-bonded high temperature SFL in several locations such as restraint hardware between the SRB aft skirt and the Mobile Launch Platform (MLP), the aft SRB/External Tank (ET) attach struts, and the forward skirt SRB/ET attach ball assembly. Future launch systems may require similar applications of SFLs for attachment and restraint hardware. A family of environmentally compatible non-lead/antimony bearing alternative SFLs have been developed including a compatible repair material. In addition, commercial applications for SFLs on transportation equipment, all types of lubricated fasteners, and energy related equipment allow for wide usage's of these new lubricants. The new SFLs trade named BOOSTERLUBE is a family of single layer thin film (0.001 inch maximum) coatings that are a unique mixture of non-hazardous pigments in a compatible resin system that allows for low temperature curing (450 F). Significant savings in energy and processing time as well as elimination of hazardous material usage and disposal would result from the non-toxic one-step SFL application. Compatible air-dry field repair lubricants will help eliminate disassembly of launch vehicle restraint hardware during critical time sensitive assembly operations.

The use of silver in self-lubricating coatings for extreme temperatures

NASA Technical Reports Server (NTRS)

Sliney, H. E.

1986-01-01

The advantages and disadvantages of elemental silver as a tribological material are discussed. It is demonstrated that the relatively high melting point of 961 deg C, softness, marked plasticity, and thermochemical stability of silver combine to make this metal useful in thin film solid lubricant coatings over a wide temperature range. Disadvantages of silver during sliding, except when used as a thin film, are shown to be gross ploughing due to plastic deformation under load with associated high friction and excessive transfer to counterface surfaces. This transfer generates an irregular surface topography with consequent undesirable changes in bearing clearance distribution. Research to overcome these disadvantages of element silver is described. A comparison is made of the tribological behavior of pure silver with that of silver formulated with other metals and high-temperature solid lubricants. The composite materials are prepared by co-depositing the powdered components with an airbrush followed by furnace heat treatment or by plasma-spraying. Composite coatings were formulated which are shown to be self-lubricating over repeated, temperature cycles from low temperature to about 900 deg C.

Fundamental interfacial studies of advanced solid lubricants and their operating environments

NASA Astrophysics Data System (ADS)

Gilley, Kevin

Solid lubricants are a class of materials that are utilized in applications and environments where traditional lubrication schemes cannot be implemented. A variety of materials display solid lubrication, and in this study a number of solid lubricants were investigated. Firstly, electrolessly deposited nickel boride alloys were annealed at different temperatures under a flow of oxygen. The surface chemistry, friction, and wear behavior of the coating were then investigated. It was found that when annealed above 550°C the coatings had a dramatic change in surface chemistry, where the Ni 3B had formed a thick layer of B2O3 on the surface. This oxide then reacted at ambient temperatures with moist air to form the lubricious compound H3BO3. This led to a coefficient of friction below 0.1 and a slight increase of the wear rate from 10 -8 mm3/Nm to 10-7 mm3/Nm. Secondly, the surface chemistry of advanced MoS2 based coatings that had been exposed to low earth orbit was investigated. It was found that this exposure produced the complete oxidation of the coatings. Also, exposure to the unique space environments resulted in the deposition of large amounts of contaminant SiO2 on the surface. Lastly the tribological properties of single crystal cadmium sulfide were investigated. There is nearly no knowledge of the tribological activity of cadmium sulfide in the literature, so the study was performed as an initial investigation into the material. It was discovered that cadmium sulfide did not show low friction, with a coefficient of friction of approximately 0.25, but did show low wear, with a wear rate of approximately 3x10-7 mm3/Nm.

Experimental evaluation of chromium-carbide-based solid lubricant coatings for use to 760 C

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher

1987-01-01

A research program is described which further developed and investigated chromium carbide based self-lubricating coatings for use to 760 C. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The three coating components were blended in powder form, applied to stainless steel substrates by plasma spraying and then diamond ground to the desired coating thickness. A variety of coating compositions was tested to determine the coating composition which gave optimum tribological results. Coatings were tested in air, helium, and hydrogen at temperatures from 25 to 760 C. Several counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications, such as piston ring/cylinder liner couples for Stirling engines. In general, silver and fluoride additions to chromium carbide reduced the friction coefficient and increased the wear resistance relative to the unmodified coating. The lubricant additives acted synergistically in reducing friction and wear.

The experimental evaluation and application of high-temperature solid lubricants. Ph.D. Thesis - Case Western Reserve Univ., 1989 Final Report

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher

1990-01-01

A research program is described which developes an understanding of high-temperature solid lubrication and experimental techniques through the development of a composite lubricant coating system. The knowledge gained through this research was then applied to a specific engineering challenge, the tribology of a sliding seal for hypersonic flight vehicles. The solid lubricant coating is a chromium carbide based composite combined with silver, which acts as a low temperature lubricant, and barium fluoride/calcium fluoride eutectic, which acts as a high-temperature lubricant. This composite coating provides good wear resistance and low friction for sliding contacts from room temperature to over 900 C in reducing or oxidative environments. The specific research on this coating included a composition screening using a foil gas bearing test rig and the use of thin silver films to reduce initial wear using a pin-on-disk test rig. The chemical stability of the materials used was also addressed. This research indicated that soft metallic films and materials which become soft at elevated temperatures are potentially good lubricants. The general results from the experiments with the model solid lubricant coating were then applied to a sliding seal design concept. This seal design requires that a braided ceramic fabric slide against a variety of metal counterface materials at temperatures from 25 to 850 C in an oxidative environment. A pin-on-disk tribometer was used to evaluate the tribological properties of these materials and to develop lubrication techniques. The results indicate that these seal materials must be lubricated to prevent wear and reduce friction. Thin films of silver, gold and calcium fluoride provided lubrication to the sliding materials.

Lubrication handbook for use in the space industry. Part A: Solid lubricants. Part B: Liquid lubricants

NASA Technical Reports Server (NTRS)

Campbell, M. E.; Thompson, M. B.

1972-01-01

This handbook provides a ready reference for many of the solid and liquid lubricants used in the space industry. Lubricants and lubricant properties are arranged systematically so that designers, engineers, and maintenance personnel in the space industry can conveniently locate data needed for their work. The handbook is divided into two major parts. Part A is a compilation of chemical and physical property data of more than 250 solid lubricants, bonded solid lubricants, dispersions and composites. Part B is a compilation of chemical and physical property data of more than 250 liquid lubricants, greases, oils, compounds and fluids. The listed materials cover a broad spectrum, from manufacturing and ground support to hardware applications for missiles and spacecraft.

The role of silver in self-lubricating coatings for use at extreme temperatures

NASA Technical Reports Server (NTRS)

Sliney, H. E.

1985-01-01

The advantages and disadvantages of elemental silver as a tribological material are discussed. It is demonstrated that the relatively high melting point of 961 deg C, softness, marked plasticity, and thermochemical stability of silver combine to make this metal useful in thin film solid lubricant coatings over a wide temperature range. Disadvantages of silver during sliding, except when used as a thin film, are shown to be gross ploughing due to plastic deformation under load with associated high friction and excessive transfer to counterface surfaces. This transfer generates an irregular surface topography with consequent undesirable changes in bearing clearance distribution. Research to overcome these disadvantages of element silver is described. A comparison is made of the tribological behavior of pure silver with that of silver formulated with other metals and high-temperature solid lubricants. The composite materials are prepared by co-depositing the powdered components with an airbrush followed by furnace heat treatment or by plasma-spraying. Composite coatings were formulated which are shown to be self-lubricating over repeated, temperature cycles from low temperature to about 900 deg C.

High Temperature Solid Lubricant Materials for Heavy Duty and Advanced Heat Engines

NASA Technical Reports Server (NTRS)

Dellacorte, C.; Wood, J. C.

1994-01-01

Advanced engine designs incorporate higher mechanical and thermal loading to achieve efficiency improvements. This approach often leads to higher operating temperatures of critical sliding elements (e.g. piston ring/cylinder wall contacts and valve guides) which compromise the use of conventional and even advanced synthetic liquid lubricants. For these applications solid lubricants must be considered. Several novel solid lubricant composites and coatings designated PS/PM200 have been employed to dry and marginally oil lubricated contacts in advanced heat engines. These applications include cylinder kits of heavy duty diesels, and high temperature Stirling engines, sidewall seals of rotary engines, and various exhaust valve and exhaust component applications. This paper describes the tribological and thermophysical properties of these tribomaterials and reviews the results of applying them to engine applications. Other potential tribological materials and applications are also discussed with particular emphasis on heavy duty and advanced heat engines.

Water Lubrication of Stainless Steel using Reduced Graphene Oxide Coating.

PubMed

Kim, Hae-Jin; Kim, Dae-Eun

2015-11-23

Lubrication of mechanical systems using water instead of conventional oil lubricants is extremely attractive from the view of resource conservation and environmental protection. However, insufficient film thickness of water due to low viscosity and chemical reaction of water with metallic materials have been a great obstacle in utilization of water as an effective lubricant. Herein, the friction between a 440 C stainless steel (SS) ball and a 440 C stainless steel (SS) plate in water lubrication could be reduced by as much as 6-times by coating the ball with reduced graphene oxide (rGO). The friction coefficient with rGO coated ball in water lubrication was comparable to the value obtained with the uncoated ball in oil lubrication. Moreover, the wear rate of the SS plate slid against the rGO coated ball in water lubrication was 3-times lower than that of the SS plate slid against the uncoated ball in oil lubrication. These results clearly demonstrated that water can be effectively utilized as a lubricant instead of oil to lower the friction and wear of SS components by coating one side with rGO. Implementation of this technology in mechanical systems is expected to aid in significant reduction of environmental pollution caused by the extensive use of oil lubricants.

Water Lubrication of Stainless Steel using Reduced Graphene Oxide Coating

NASA Astrophysics Data System (ADS)

Kim, Hae-Jin; Kim, Dae-Eun

2015-11-01

Lubrication of mechanical systems using water instead of conventional oil lubricants is extremely attractive from the view of resource conservation and environmental protection. However, insufficient film thickness of water due to low viscosity and chemical reaction of water with metallic materials have been a great obstacle in utilization of water as an effective lubricant. Herein, the friction between a 440 C stainless steel (SS) ball and a 440 C stainless steel (SS) plate in water lubrication could be reduced by as much as 6-times by coating the ball with reduced graphene oxide (rGO). The friction coefficient with rGO coated ball in water lubrication was comparable to the value obtained with the uncoated ball in oil lubrication. Moreover, the wear rate of the SS plate slid against the rGO coated ball in water lubrication was 3-times lower than that of the SS plate slid against the uncoated ball in oil lubrication. These results clearly demonstrated that water can be effectively utilized as a lubricant instead of oil to lower the friction and wear of SS components by coating one side with rGO. Implementation of this technology in mechanical systems is expected to aid in significant reduction of environmental pollution caused by the extensive use of oil lubricants.

Composite coating for low friction and wear applications and method thereof

DOEpatents

Besmann, T.M.; Blau, P.J.; Lee, W.Y.; Bae, Y.W.

1998-01-20

An article having a multiphase composite lubricant coating of a hard refractory matrix phase of titanium nitride dispersed with particles of a solid lubricating phase of molybdenum disulfide is prepared by heating the article to temperatures between 350 and 850 C in a reaction vessel at a reduced pressure and passing a gaseous mixture of Ti((CH{sub 3}){sub 2}N){sub 4}, MoF{sub 6}, H{sub 2}S and NH{sub 3} over the heated article forming a multiphase composite lubricant coating on the article. 1 fig.

Composite coating for low friction and wear applications and method thereof

DOEpatents

Besmann, Theodore M.; Blau, Peter J.; Lee, Woo Y.; Bae, Yong W.

1998-01-01

An article having a multiphase composite lubricant coating of a hard refractory matrix phase of titanium nitride dispersed with particles of a solid lubricating phase of molybdenum disulfide is prepared by heating the article to temperatures between 350.degree. and 850.degree. C. in a reaction vessel at a reduced pressure and passing a gaseous mixture of Ti((CH.sub.3).sub.2 N).sub.4, MoF.sub.6, H.sub.2 S and NH.sub.3 over the heated article forming a multiphase composite lubricant coating on the article.

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.

Water Lubrication of Stainless Steel using Reduced Graphene Oxide Coating

PubMed Central

Kim, Hae-Jin; Kim, Dae-Eun

2015-01-01

Lubrication of mechanical systems using water instead of conventional oil lubricants is extremely attractive from the view of resource conservation and environmental protection. However, insufficient film thickness of water due to low viscosity and chemical reaction of water with metallic materials have been a great obstacle in utilization of water as an effective lubricant. Herein, the friction between a 440 C stainless steel (SS) ball and a 440 C stainless steel (SS) plate in water lubrication could be reduced by as much as 6-times by coating the ball with reduced graphene oxide (rGO). The friction coefficient with rGO coated ball in water lubrication was comparable to the value obtained with the uncoated ball in oil lubrication. Moreover, the wear rate of the SS plate slid against the rGO coated ball in water lubrication was 3-times lower than that of the SS plate slid against the uncoated ball in oil lubrication. These results clearly demonstrated that water can be effectively utilized as a lubricant instead of oil to lower the friction and wear of SS components by coating one side with rGO. Implementation of this technology in mechanical systems is expected to aid in significant reduction of environmental pollution caused by the extensive use of oil lubricants. PMID:26593645

The Effect of Journal Roughness and Foil Coatings on the Performance of Heavily Loaded Foil Air Bearings

NASA Technical Reports Server (NTRS)

Radil, Kevin C.; DellaCorte, Christopher

2001-01-01

Foil air bearing load capacity tests were conducted to investigate if a solid lubricant coating applied to the surface of the bearing's top foil can function as a break-in coating. Two foil coating materials, a conventional soft polymer film (polyimide) and a hard ceramic (alumina), were independently evaluated against as-ground and worn (run-in) journals coated with NASA PS304, a high-temperature solid lubricant composite coating. The foil coatings were evaluated at journal rotational speeds of 30,000 rpm and at 25 C. Tests were also performed on a foil bearing with a bare (uncoated) nickel-based superalloy top foil to establish a baseline for comparison. The test results indicate that the presence of a top foil solid lubricant coating is effective at increasing the load capacity performance of the foil bearing. Compared to the uncoated baseline, the addition of the soft polymer coating on the top foil increased the bearing load coefficient by 120% when operating against an as-ground journal surface and 85 percent against a run-in journal surface. The alumina coating increased the load coefficient by 40% against the as-ground journal but did not have any affect when the bearing was operated with the run-in journal. The results suggest that the addition of solid lubricant films provide added lubrication when the air film is marginal indicating that as the load capacity is approached foil air bearings transition from hydrodynamic to mixed and boundary lubrication.

Composition optimization of chromium carbide based solid lubricant coatings for foil gas bearings at temperatures to 650 C

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher

1987-01-01

A test program to determine the optimum composition of chromium carbide based solid lubricant coatings for compliant gas bearings is described. The friction and wear properties of the coatings are evaluated using a foil gas bearing test apparatus. The various coatings were prepared by powder blending, then plasma sprayed onto Inconel 718 test journals and diamond ground to the desired coating thickness and surface finish. The journals were operated against preoxidized nickel-chromium alloy foils. The test bearings were subjected to repeated start/stop cycles under a 14 kPa (2 psi) bearing unit load. The bearings were tested for 9000 start/stop cycles or until the specimen wear reached a predetermined failure level. In general, the addition of silver and eutectic to the chromium carbide base stock significantly reduced foil wear and increased journal coating wear. The optimum coating composition, PS212 (70 wt% metal bonded Cr3C2, 15 wt% Ag, 15% BaF2/CaF2 eutectic), reduced foil wear by a factor of two and displayed coating wear well within acceptable limits. The load capacity of the bearing using the plasma-sprayed coating prior to and after a run-in period was ascertained and compared to polished Inconel 718 specimens.

High performance solid and liquid lubricants: An industrial guide

NASA Technical Reports Server (NTRS)

Mcmurtrey, Ernest L.

1987-01-01

This handbook is intended to provide a ready reference for many of the solid and liquid lubricants used in the space industry. Lubricants and lubricant properties are arranged systematically so that designers, engineers, and maintenance personnel can conveniently locate data needed for their work. This handbook is divided into two major parts (A and B). Part A is a compilation of solid lubricant suppliers information on chemical and physical property of data of more than 250 solid lubricants, bonded solid lubricants, dispersions, and composites. Part B is a compilation of chemical and physical property data of more than 250 liquid lubricants, greases, oils, compounds, and fluids. The listed materials cover a broad spectrum from manufacturing and ground support to hardware applications of spacecraft.

Radiofrequency-sputtered coatings for lubrication system components and other complex surfaces

NASA Technical Reports Server (NTRS)

Spalvins, T.

1972-01-01

Irregularly shaped surfaces, such as lubrication system components (ball bearings, seals, gears, etc.), can be coated on all surfaces, including irregular shapes, when radiofrequency sputtering is used. When the specimen is properly located with respect to the sputtering target, the sputtered material covers the entire surface of the object irrespective of its geometrical configuration. An adherent, dense film is formed. The film thickness varies from 20 to 50 percent on, for example, a hearing cage or race depending on its geometry. When sputtered solid film lubricants such as molybdenum disulfide are used, a film thickness only of the order of 10 to the minus 7th power m (thousands of angstroms) is required at the contacting areas. It is only essential to determine the required film thickness at the critical areas in need of lubrication. The sections outside the areas to be lubricated fall within the thickness deviation range of 20 to 50 percent, which still constitutes a negligible change respect to tolerance requirements.

The Effect of Compositional Tailoring on the Thermal Expansion and Tribological Properties of PS300: A Solid Lubricant Composite Coating

NASA Technical Reports Server (NTRS)

DellaCorte, C.; Fellenstein, J. A.

1996-01-01

This paper describes a research program in which the goal is to alter the thermal expansion coefficient of a composite solid lubricant coating, PS300, by compositional tailoring. PS300 is a plasma sprayed coating consisting of chrome oxide, silver and barium fluoride/calcium fluoride eutectic in NiCr binder. By adjusting the composition, the thermal expansion coefficient can be altered, and hence chosen, to more closely match a selected substrate preventing coating spallation at extreme temperatures. Thermal expansion coefficients (CTE) for a variety of compositions were measured from 25 to 800 C using a commercial dilatometer. The CTE's ranged from 7.0 to 13 x lO(exp -6)/deg C depending on the binder content. Subsequent tribological testing of a modified composition indicated that friction and wear properties were relatively insensitive to compositional tailoring.

Principles of ESCA and application to metal corrosion, coating and lubrication

NASA Technical Reports Server (NTRS)

Wheeler, D. R.

1978-01-01

The principles of ESCA (electron spectroscopy for chemical analysis) were described by comparison with other spectroscopic techniques. The advantages and disadvantages of ESCA as compared to other surface sensitive analytical techniques were evaluated. The use of ESCA was illustrated by actual applications to oxidation of steel and Rene 41, the chemistry of lubricant additives on steel, and the composition of sputter deposited hard coatings. A bibliography of material that was useful for further study of ESCA was presented and commented upon.

High-Temperature Solid Lubricants Developed by NASA Lewis Offer Virtually "Unlimited Life" for Oil-Free Turbomachinery

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher; Valco, Mark J.

1999-01-01

The NASA Lewis Research Center is capitalizing on breakthroughs in foil air bearing performance, tribological coatings, and computer analyses to formulate the Oil-free Turbomachinery Program. The program s long-term goal is to develop an innovative, yet practical, oil-free aeropropulsion gas turbine engine that floats on advanced air bearings. This type of engine would operate at higher speeds and temperatures with lower weight and friction than conventional oil-lubricated engines. During startup and shutdown, solid lubricant coatings are required to prevent wear in such engines before the self-generating air-lubrication film develops. NASA s Tribology Branch has created PS304, a chrome-oxide-based plasma spray coating specifically tailored for shafts run against foil bearings. PS304 contains silver and barium fluoride/calcium fluoride eutectic (BaF2/CaF2) lubricant additives that, together, provide lubrication from cold start temperatures to over 650 C, the maximum use temperature for foil bearings. Recent lab tests show that bearings lubricated with PS304 survive over 100 000 start-stop cycles without experiencing any degradation in performance due to wear. The accompanying photograph shows a test bearing after it was run at 650 C. The rubbing process created a "polished" surface that enhances bearing load capacity.

Solid Lubrication Fundamentals and Applications. Chapter 6

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

2000-01-01

This chapter focuses attention on the friction and wear properties of selected solid lubricating films to aid users in choosing the best lubricant, deposition conditions, and operational variables. For simplicity, discussion of the tribological properties of concern is separated into two parts. The first part of the chapter discusses the different solid lubricating films selected for study including commercially developed solid film lubricants: (1) bonded molybdenum disulfide (MoS2), (2) magnetron-sputtered MoS2, (3) ion-plated silver, (4) ion-plated lead, (5) magnetron-sputtered diamondlike carbon (MS DLC), and (6) plasma-assisted, chemical-vapor-deposited diamondlike carbon (PACVD DEC) films. Marked differences in the friction and wear properties of the different films resulted from the different environmental conditions (ultrahigh vacuum, humid air, and dry nitrogen) and the solid film lubricant materials. The second part of the chapter discusses the physical and chemical characteristics, friction behavior, and endurance life of the magnetron-sputtered MoS2 films. The role of interface species and the effects of applied load, film thickness, oxygen pressure, environment, and temperature on the friction and wear properties are considered.

Thermal Processing Effects on the Adhesive Strength of PS304 High Temperature Solid Lubricant Coatings

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher; Edmonds, Brian J.; Benoy, Patricia A.

2001-01-01

In this paper the effects of post deposition heat treatments on the cohesive and adhesive strength properties of PS304, a plasma sprayed nickel-chrome based, high temperature solid lubricant coating deposited on stainless steel, are studied. Plasma spray deposited coating samples were exposed in air at temperatures from 432 to 650 C for up to 500 hr to promote residual stress relief, enhance particle to particle bonding and increase coating to substrate bond strength. Coating pull-off strength was measured using a commercial adhesion tester that utilizes 13 mm diameter aluminum pull studs attached to the coating surface with epoxy. Pull off force was automatically recorded and converted to coating pull off strength. As deposited coating samples were also tested as a baseline. The as-deposited (untreated) samples either delaminated at the coating-substrate interface or failed internally (cohesive failure) at about 17 MPa. Samples heat treated at temperatures above 540 C for 100 hr or at 600 C or above for more than 24 hr exhibited strengths above 31 MPa, nearly a two fold increase. Coating failure occurred inside the body of the coating (cohesive failure) for nearly all of the heat-treated samples and only occasionally at the coating substrate interface (adhesive failure). Metallographic analyses of heat-treated coatings indicate that the Nickel-Chromium binder in the PS304 appears to have segregated into two phases, a high nickel matrix phase and a high chromium precipitated phase. Analysis of the precipitates indicates the presence of silicon, a constituent of a flow enhancing additive in the commercial NiCr powder. The exact nature and structure of the precipitate phase is not known. This microstructural change is believed to be partially responsible for the coating strength increase. Diffusion bonding between particles may also be playing a role. Increasing the heat treatment temperature, exposure time or both accelerate the heat treatment process. Preliminary

Solid Lubrication Fundamentals and Applications: Introduction and Background. Revision 1

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1998-01-01

This chapter presents an introduction and historical background to the field of tribology, especially solid lubrication and lubricants and sets them in the perspective of techniques and materials in lubrication. Also, solid and liquid lubrication films are defined and described.

Solid Lubrication Fundamentals and Applications. Chapter 1; Introduction and Background

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1996-01-01

This chapter presents an introduction and historical background to the field of tribology, especially solid lubrication and lubricants and sets them in the perspective of techniques and materials in lubrication. Also, solid and liquid lubrication films are defined and described.

Solid lubrication design methodology

NASA Technical Reports Server (NTRS)

Aggarwal, B. B.; Yonushonis, T. M.; Bovenkerk, R. L.

1984-01-01

A single element traction rig was used to measure the traction forces at the contact of a ball against a flat disc at room temperature under combined rolling and sliding. The load and speed conditions were selected to match those anticipated for bearing applications in adiabatic diesel engines. The test program showed that the magnitude of traction forces were almost the same for all the lubricants tested; a lubricant should, therefore, be selected on the basis of its ability to prevent wear of the contact surfaces. Traction vs. slide/roll ratio curves were similar to those for liquid lubricants but the traction forces were an order of magnitude higher. The test data was used to derive equations to predict traction force as a function of contact stress and rolling speed. Qualitative design guidelines for solid lubricated concentrated contacts are proposed.

Solid lubricant behavior of MoS2 and WSe2-based nanocomposite coatings

NASA Astrophysics Data System (ADS)

Domínguez-Meister, Santiago; Rojas, Teresa Cristina; Brizuela, Marta; Sánchez-López, Juan Carlos

2017-12-01

Tribological coatings made of MoS2 and WSe2 phases and their corresponding combinations with tungsten carbide (WC) were prepared by non-reactive magnetron sputtering of individual targets of similar composition. A comparative tribological analysis of these multiphase coatings was done in both ambient air (30-40% relative humidity, RH) and dry nitrogen (RH<7%) environments using the same tribometer and testing conditions. A nanostructural study using advanced transmission electron microscopy of the initial coatings and examination of the counterfaces after the friction test using different analytical tools helped to elucidate what governs the tribological behavior for each type of environment. This allowed conclusions to be made about the influence of the coating microstructure and composition on the tribological response. The best performance obtained with a WSex film (specific wear rate of 2 × 10-8 mm3 N-1m-1 and a friction coefficient of 0.03-0.05) was compared with that of the well-established MoS2 lubricant material.

Tribological performance of quaternary CrSiCN coatings under dry and lubricated conditions

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

Lorenzo-Martin, C.; Ajayi, O.; Erdemir, A.

This paper presents an experimental study of friction and wear performance of quaternary CrSiCN coatings deposited on a hardened H-13 steel substrate by a plasma enhanced magnetron sputtering (PEMS) technique. Friction and wear tests were conducted with a reciprocating line contact between a hardened 4370 steel roller and coated and uncoated flat specimens under dry and lubricated conditions. The effects of coating thickness (1, 3.5 and 7.5 μm) on the mechanical properties, friction and wear performance were also assessed. In dry sliding, the friction of coated surfaces was about the same as for uncoated surfaces, except for the 1-μm coating,more » which had higher friction. Friction for coated surfaces under lubricated contact was in general higher than for uncoated surfaces. There was no measurable wear on any of the coated surfaces, under either dry or lubricated conditions. However, wear was higher on the steel roller counterface sliding against the coated surfaces, with the amount of wear proportional to the mating coating thickness. The effectiveness of formulated lubricant additives was also modified by the coating, resulting in major effects on friction and wear behavior. Finally, this reduction in lubricant additive efficacy is due to the fact that the additives were designed and optimized for ferrous surfaces.« less

Tribological performance of quaternary CrSiCN coatings under dry and lubricated conditions

DOE PAGES

Lorenzo-Martin, C.; Ajayi, O.; Erdemir, A.; ...

2017-06-15

This paper presents an experimental study of friction and wear performance of quaternary CrSiCN coatings deposited on a hardened H-13 steel substrate by a plasma enhanced magnetron sputtering (PEMS) technique. Friction and wear tests were conducted with a reciprocating line contact between a hardened 4370 steel roller and coated and uncoated flat specimens under dry and lubricated conditions. The effects of coating thickness (1, 3.5 and 7.5 μm) on the mechanical properties, friction and wear performance were also assessed. In dry sliding, the friction of coated surfaces was about the same as for uncoated surfaces, except for the 1-μm coating,more » which had higher friction. Friction for coated surfaces under lubricated contact was in general higher than for uncoated surfaces. There was no measurable wear on any of the coated surfaces, under either dry or lubricated conditions. However, wear was higher on the steel roller counterface sliding against the coated surfaces, with the amount of wear proportional to the mating coating thickness. The effectiveness of formulated lubricant additives was also modified by the coating, resulting in major effects on friction and wear behavior. Finally, this reduction in lubricant additive efficacy is due to the fact that the additives were designed and optimized for ferrous surfaces.« less

Microindentation hardness testing of coatings: techniques and interpretation of data

NASA Astrophysics Data System (ADS)

Blau, P. J.

1986-09-01

This paper addresses the problems and promises of micro-indentation testing of thin solid films. It has discussed basic penetration hardness testing philosophy, the peculiarities of low load-shallow penetration tests of uncoated metals, and it has compared coated with uncoated behavior so that some of the unique responses of coatings can be distinguished from typical hardness versus load behavior. As the uses of thin solid coatings with technological interest continue to proliferate, microindentation testing methodology will increasingly be challenged to provide useful tools for their characterization. The understanding of microindentation response must go hand-in-hand with machine design so that the capability of measurement precision does not outstrip our abilities to interpret test results in a meaningful way.

Solid lubricant behavior of MoS2 and WSe2-based nanocomposite coatings

PubMed Central

Domínguez-Meister, Santiago; Rojas, Teresa Cristina; Brizuela, Marta; Sánchez-López, Juan Carlos

2017-01-01

Abstract Tribological coatings made of MoS2 and WSe2 phases and their corresponding combinations with tungsten carbide (WC) were prepared by non-reactive magnetron sputtering of individual targets of similar composition. A comparative tribological analysis of these multiphase coatings was done in both ambient air (30–40% relative humidity, RH) and dry nitrogen (RH<7%) environments using the same tribometer and testing conditions. A nanostructural study using advanced transmission electron microscopy of the initial coatings and examination of the counterfaces after the friction test using different analytical tools helped to elucidate what governs the tribological behavior for each type of environment. This allowed conclusions to be made about the influence of the coating microstructure and composition on the tribological response. The best performance obtained with a WSex film (specific wear rate of 2 × 10−8 mm3 N–1m–1 and a friction coefficient of 0.03–0.05) was compared with that of the well-established MoS2 lubricant material. PMID:28458736

Effect of the External Lubrication Method for a Rotary Tablet Press on the Adhesion of the Film Coating Layer.

PubMed

Kondo, Hisami; Toyota, Hiroyasu; Kamiya, Takayuki; Yamashita, Kazunari; Hakomori, Tadashi; Imoto, Junko; Kimura, Shin-Ichiro; Iwao, Yasunori; Itai, Shigeru

2017-01-01

External lubrication is a useful method which reduces the adhesion of powder to punches and dies by spraying lubricants during the tableting process. However, no information is available on whether the tablets prepared using an external lubrication system can be applicable for a film coating process. In this study, we evaluated the adhesion force of the film coating layer to the surface of tablets prepared using an external lubrication method, compared with those prepared using internal lubrication method. We also evaluated wettability, roughness and lubricant distribution state on the tablet surface before film coating, and investigated the relationship between peeling of the film coating layer and these tablet surface properties. Increasing lubrication through the external lubrication method decreased wettability of the tablet surface. However, no change was observed in the adhesion force of the film coating layer. On the other hand, increasing lubrication through the internal lubrication method, decreased both wettability of the tablet surface and the adhesion force of the film coating layer. The magnesium stearate distribution state on the tablet surface was assessed using an X-ray fluorescent analyzer and lubricant agglomerates were observed in the case of the internal lubrication method. However, the lubricant was uniformly dispersed in the external lubrication samples. These results indicate that the distribution state of the lubricant affects the adhesion force of the film coating layer, and external lubrication maintained sufficient lubricity and adhesion force of the film coating layer with a small amount of lubricant.

Plasma-sprayed self-lubricating coatings

NASA Technical Reports Server (NTRS)

Nakamura, H. H.; Logan, W. R.; Harada, Y.

1982-01-01

One of the most important criterion for acceptable commercial application of a multiple phase composition is uniformity and reproducibility. This means that the performance characteristics of the coat - e.g., its lubricating properties, bond strength to the substrate, and thermal properties - can be readily predicted to give a desired performance. The improvement of uniformity and reproducibility of the coats, the oxidation behavior at three temperature ranges, the effect of bond coat and the effect of preheat treatment as measured by adhesive strength tests, coating examination procedures, and physical property measurements were studied. The following modifications improved the uniformity and reproducibility: (1) changes and closer control in the particle size range of the raw materials used, (2) increasing the binder content from 3.2% to 4.1% (dried weight), and (3) analytical processing procedures using step by step checking to assure consistency.

Tribological Properties of CrN Coating Under Lubrication Conditions

NASA Astrophysics Data System (ADS)

Lubas, Janusz

2012-08-01

The paper presents research results of the influence of CrN coating on the friction parameters in friction pairs under lubricated friction conditions. The formed CrN homogeneous coating and CrN-steel 46Cr2 "ring" structure coating was matched under test conditions with a counterpart made from SAE-48 and SAE-783 bearing alloys. Tested sliding pairs were lubricated with 5W/40 Lotos synthetic engine oil. The tribological test was conducted on block-on-ring tester. The applied modification technologies of the surface layer of steel allowed for obtaining construction materials with pre-determined tribological characteristics required for the elements of friction pairs in lubricated contact. The results of the tests proved the possibility of implementing CrN coating in friction pairs, which work under mixed friction conditions. The results showed differences in the wear of bearing alloy, as the effect of the interaction between the co-operating surface layers and of the physiochemical changes of their surfaces, induced by external forces. The smallest wear of the bearing alloy occurs during the cooperation with the nitrided layer, whereas the largest wear occurs during the cooperation with the homogenous CrN coating. The CrN coating-46Cr2 steel "ring structure" decreases friction resistance during the start-up of the sliding pair, as well as lowers the level of the friction force and temperature in the friction area during co-operation with SAE-783 bearing alloys.

Preliminary Evaluation of PS300: A New Self-Lubricating High Temperature Composite Coating for Use to 800 C

NASA Technical Reports Server (NTRS)

Dellacorte, C.; Edmonds, B. J.

1995-01-01

This paper introduces PS300, a plasma sprayed, self-lubricating composite coating for use in sliding contacts at temperatures to 800 C. PS300 is a metal bonded chrome oxide coating with silver and BaF2/CaF2 eutectic solid lubricant additives. PS300 is similar to PS200, a chromium carbide based coating, which is currently being investigated for a variety of tribological applications. In pin-on-disk testing up to 650 C, PS300 exhibited comparable friction and wear properties to PS200. The PS300 matrix, which is predominantly chromium oxide rather than chromium carbide, does not require diamond grinding and polishes readily with silicon carbide abrasives greatly reducing manufacturing costs compared to PS200. It is anticipated that PS300 has potential for sliding bearing and seal applications in both aerospace and general industry.

Dynamics of solid lubrication as observed by optical microscopy

NASA Technical Reports Server (NTRS)

Sliney, H. E.

1976-01-01

A bench metallograph was converted into a micro contact imager by the addition of a tribometer employing a steel ball in sliding contact with a glass disk. The sliding contact was viewed in real time by means of projection microscope optics. The dynamics of abrasive particles and of solid lubricant particles within the contact were observed in detail. The contact was characterized by a constantly changing pattern of elastic strain with the passage of surface discontinuities and solid particles. Abrasive particles fragmented upon entering the contact, embedded in one surface and scratched the other; in contrast, the solid lubricant particles flowed plastically into thin films. The rheological behavior of the lubricating solids gave every appearance of a paste-like consistency within the Hertzian contact.

The Effects of Substrate Material and Thermal Processing Atmosphere on the Strength of PS304: A High Temperature Solid Lubricant Coating

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher

2002-01-01

PS304, a plasma spray deposited solid lubricant coating developed for high temperature sliding contacts was deposited on nine different substrate metals, heat treated at 650C in either air or argon and subsequently tested for strength using a commercially available pull-off adhesion test. Some samples were examined metallographically to help elucidate and explain the results. As deposited coatings exhibit pull-off strengths typically between 16 and 20 MPa with failure occuring (cohesively) within the coating. Heat treatment in argon at 650 C results in a slight increase in coating (cohesive) strength of about 30 percent to 21 to 27 MPa. Heat treatment in air at 650 C results in a dramatic increase in strength to over 30 MPa, exceeding the strength of the epoxy used in the pull test. Cross section metallographic analyses show that no microstructural coating changes occur following the argon heat treatments, however, exposure to air at 650C gives rise to the formation of a second chromium-rich phase precipitate within the PS304 NiCr constituent which provides a strengthening effect and a slight (approximately 5 percent) coating thickness increase. Subsequent heat treatments do not result in any further coating changes. Based upon these studies, PS304 is a suitable coating for use on a wide variety of high temperature substrates and must be heat treated following deposition to enhance strength and ensure dimensional stability.

Nanolubrication: patterned lubricating films using ultraviolet (UV) irradiation on hard disks.

PubMed

Zhang, J; Hsu, S M; Liew, Y F

2007-01-01

Nanolubrication is emerging to be the key technical barrier in many devices. One of the key attributes for successful device lubrication is self-sustainability using only several molecular layers. For single molecular species lubrication, one desires bonding strength and molecular mobility to repair the contact by diffusing back to the contact. One way to achieve this is the use of mask to shield the surface with a patterned surface texture, put a monolayer on the surface and induce bonding. Then re-deposit mobile molecules on the surface to bring the thickness back to the desired thickness. This paper describes the use of long wavelength UV irradiation (320-390 nm) to induce bonding of a perfluoropolyether (PFPE) on CN(x) disks for magnetic hard disk application. This allows the use of irradiation to control the degree of bonding on CN(x) coatings. The effect of induced bonding based on this wavelength was studied by comparing 100% mobile PFPE, 100% bonded PFPE, and a mixture of mobile and bonded PFPE in a series of laboratory tests. Using a lateral force microscope, a diamond-tipped atomic force microscope, and a ball-on-inclined plane apparatus, the friction and wear characteristics of these three cases were obtained. Results suggested that the mixed PFPE has the highest shear rupture strength.

The PM-200 lubrication system

NASA Technical Reports Server (NTRS)

Sliney, Harold E.

1991-01-01

Plasma sprayed composite coating of metal-bonded chromium carbide with additions of silver and thermochemically stable fluorides were previously reported to be lubricative in pin on desk bench tests from room temperature to 900 C. An early coating formulation of this type, designated as PS-200, was successfully tested as a cylinder coating in a Stirling engine at a TRRT of 760 C in a hydrogen atmosphere, and as a backup lubricant for gas bearings to 650 C. A subsequent optimization program has shown that tribological properties are further improved by increasing the solid lubricant content. The improved coating is designated as PS-212. The same powder formulation was used to make free-standing powder metallurgy (PM-212) parts by sintering or hot isostatic pressing. The process is very attractive for making parts that cannot be readily plasma sprayed such as bushings and cylinders that have small bore diameters and/or high length to diameter ratios. The properties of coatings and free-standing parts fabricated from these powders are reviewed.

Pulse electrodeposition of self-lubricating Ni-W/PTFE nanocomposite coatings on mild steel surface

NASA Astrophysics Data System (ADS)

Sangeetha, S.; Kalaignan, G. Paruthimal; Anthuvan, J. Tennis

2015-12-01

Ni-W/PTFE nanocomposite coatings with various contents of PTFE (polytetafluoroethylene) particles were prepared by pulse current (PC) electrodeposition from the Ni-W plating bath containing self lubricant PTFE particles to be co-deposited. Co-deposited PTFE particulates were uniformly distributed in the Ni-W alloy matrix. The coatings were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), X-ray Diffractometry (XRD) and Vicker's micro hardness tester. Tafel Polarization and electrochemical Impedance methods were used to evaluate the corrosion resistance behaviour of the nanocomposite coatings in 3.5% NaCl solution. It was found that, the Ni-W/PTFE nanocomposite coating has better corrosion resistance than the Ni-W alloy coating. Surface roughness and friction coefficient of the coated samples were assessed by Mitutoyo Surftest SJ-310 (ISO1997) and Scratch tester TR-101-M4 respectively. The contact angle (CA) of a water droplet on the surface of nanocomposite coating was measured by Optical Contact Goniometry (OCA 35). These results indicated that, the addition of PTFE in the Ni-W alloy matrix has resulted moderate microhardness, smooth surface, less friction coefficient, excellent water repellency and enhanced corrosion resistance of the nanocomposite coatings.

Lubricating system for thermal medium delivery parts in a gas turbine

DOEpatents

Mashey, Thomas Charles

2002-01-01

Cooling steam delivery tubes extend axially along the outer rim of a gas turbine rotor for supplying cooling steam to and returning spent cooling steam from the turbine buckets. Because of the high friction forces at the interface of the tubes and supporting elements due to rotor rotation, a low coefficient of friction coating is provided at the interface of the tubes and support elements. On each surface, a first coating of a cobalt-based alloy is sprayed onto the surface at high temperature. A portion of the first coating is machined off to provide a smooth, hard surface. A second ceramic-based solid film lubricant is sprayed onto the first coating. By reducing the resistance to axial displacement of the tubes relative to the supporting elements due to thermal expansion, the service life of the tubes is substantially extended.

Effects of silver and group 2 fluorides addition to plasma sprayed chromium carbide high temperature solid lubricant for foil gas bearing to 650 deg C

NASA Technical Reports Server (NTRS)

Wagner, R. C.; Sliney, H. E.

1984-01-01

A new self-lubricating coating composition of nickel aluminide-bonded chromium carbide formulated with silver and Group II fluorides was developed in a research program on high temperature solid lubricants. One of the proposed applications for this new coating composition is as a wide temperature spectrum solid lubricant for complaint foil gas bearings. Friction and wear properties were obtained using a foil gas bearing start/stop apparatus at temperatures from 25 to 650 C. The journals were Inconel 718. Some were coated with the plasma sprayed experimental coating, others with unmodified nickel aluminide/chromium carbide as a baseline for comparison. The addtitional components were provided to assist in achieving low friction over the temperature range of interest. Uncoated, preoxidized Inconel X-750 foil bearings were operated against these surfaces. The foils were subjected to repeated start/stop cycles under a 14-kPa (2-psi) bearing unit loading. Sliding contact occurred during lift-off and coastdown at surface velocities less than 6 m/s (3000 rpm). Testing continued until 9000 start/stop cycles were accumulated or until a rise in starting torque indicated the journal/bearing had failed. Comparison in coating performance as well as discussions of their properties and methods of application are given.

Principles of ESCA and applications to metal corrosion, coating and lubrication. [Electron Spectroscopy for Chemical Analysis

NASA Technical Reports Server (NTRS)

Wheeler, D. R.

1978-01-01

The principles of ESCA (electron spectroscopy for chemical analysis) are described by comparison with other spectroscopic techniques. The advantages and disadvantages of ESCA as compared to other surface sensitive analytical techniques are evaluated. The use of ESCA is illustrated by actual applications to oxidation of steel and Rene 41, the chemistry of lubricant additives on steel, and the composition of sputter deposited hard coatings. Finally, a bibliography of material that is useful for further study of ESCA is presented and commented upon.

Lubrication by Diamond and Diamondlike Carbon Coatings

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1997-01-01

Regardless of environment (ultrahigh vacuum, humid air, dry nitrogen, or water), ion-beam-deposited diamondlike carbon (DLC) and nitrogen-ion-implanted, chemical-vapor-deposited (CVD) diamond films had low steady-state coefficients of friction (less than 0.1) and low wear rates (less than or equal to 10(exp -6)cu mm/N(dot)m). These films can be used as effective wear-resistant, self-lubricating coatings regardless of environment. On the other hand, as-deposited, fine-grain CVD diamond films; polished, coarse-grain CVD diamond films; and polished and then fluorinated, coarse-grain CVD diamond films can be used as effective wear-resistant, self-lubricating coatings in humid air, in dry nitrogen, and in water, but they had a high coefficient of friction and a high wear rate in ultrahigh vacuum. The polished, coarse-grain CVD diamond film revealed an extremely low wear rate, far less than 10(exp 10) cu mm/N(dot)m, in water.

Metal Coatings

NASA Technical Reports Server (NTRS)

1994-01-01

During the Apollo Program, General Magnaplate Corporation developed process techniques for bonding dry lubricant coatings to space metals. The coatings were not susceptible to outgassing and offered enhanced surface hardness and superior resistance to corrosion and wear. This development was necessary because conventional lubrication processes were inadequate for lightweight materials used in Apollo components. General Magnaplate built on the original technology and became a leader in development of high performance metallurgical surface enhancement coatings - "synergistic" coatings, - which are used in applications from pizza making to laser manufacture. Each of the coatings is designed to protect a specific metal or group of metals to solve problems encountered under operating conditions.

Cost-Cutting Powdered Lubricant

NASA Technical Reports Server (NTRS)

2005-01-01

Scientists at NASA's Glenn Research Center developed a high-temperature, solid lubricant coating material that is saving the manufacturing industry millions of dollars. The material came out of 3 decades of tribological research, work studying high-temperature friction, lubrication, and the wearing of interacting surfaces that are in relative motion. It was developed as a shaft coating deposited by thermal spraying to protect foil air bearings used in oil-free turbomachinery, like gas turbines, and is meant to be part of a larger project: an oil-free aircraft engine capable of operating at high temperatures with increased reliability, lowered weight, reduced maintenance requirements, and increased power. This advanced coating, PS300, is a self-lubricating bearing material containing chromium oxide, with additions of a low-temperature start up lubricant (silver) and a high-temperature lubricant, making it remarkably stable at high temperatures, and better suited than previously available materials for high-stress conditions. It improves efficiency, lowers friction, reduces emissions, and has been used by NASA in advanced aeropropulsion engines, refrigeration compressors, turbochargers, and hybrid electrical turbogenerators. PS300 is ideal in any application where lowered weight and reduced maintenance are desired, and high-temperature uses and heavy operating speeds are expected. It has notable uses for the Space Agency, but it has even further-reaching potential for the industrial realm.

High Temperature Solid Lubricant Coating for High Temperature Wear Applications

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher (Inventor); Edmonds, Brian J (Inventor)

2014-01-01

A self-lubricating, friction and wear reducing composite useful over a wide temperature range is described herein. The composite includes metal bonded chromium oxide dispersed in a metal binder having a substantial amount of nickel. The composite contains a fluoride of at least one Group I, Group II, or rare earth metal, and optionally a low temperature lubricant metal.

Strain-tolerant ceramic coated seal

DOEpatents

Schienle, James L.; Strangman, Thomas E.

1994-01-01

A metallic regenerator seal is provided having multi-layer coating comprising a NiCrAlY bond layer, a yttria stabilized zirconia (YSZ) intermediate layer, and a ceramic high temperature solid lubricant surface layer comprising zinc oxide, calcium fluoride, and tin oxide. An array of discontinuous grooves is laser machined into the outer surface of the solid lubricant surface layer making the coating strain tolerant.

TiN-Coating Effects on Stainless Steel Tribological Behavior Under Dry and Lubricated Conditions

NASA Astrophysics Data System (ADS)

Zhang, Liqiang; Yang, Huisheng; Pang, Xiaolu; Gao, Kewei; Tran, Hai T.; Volinsky, Alex A.

2014-04-01

The tribological properties of magnetron sputtered titanium nitride coating on 316L steel, sliding against Si3N4 ceramic ball under dry friction and synthetic perspiration lubrication, were investigated. The morphology of the worn surface and the elemental composition of the wear debris were examined by scanning electron microscopy and energy dispersive spectroscopy. TiN coatings and 316L stainless steel had better tribological properties under synthetic perspiration lubrication than under dry friction. Among the three tested materials (316L, 1.6 and 2.4 μm TiN coatings), 2.4 μm TiN coating exhibits the best wear resistance. The difference in wear damage of the three materials is essentially due to the wear mechanisms. For the TiN coating, the damage is attributed to abrasive wear under synthetic perspiration lubrication and the complex interactive mechanisms, including abrasive and adhesive wear, along with plastic deformation, under dry friction.

Carbon-based tribofilms from lubricating oils

NASA Astrophysics Data System (ADS)

Erdemir, Ali; Ramirez, Giovanni; Eryilmaz, Osman L.; Narayanan, Badri; Liao, Yifeng; Kamath, Ganesh; Sankaranarayanan, Subramanian K. R. S.

2016-08-01

Moving mechanical interfaces are commonly lubricated and separated by a combination of fluid films and solid ‘tribofilms’, which together ensure easy slippage and long wear life. The efficacy of the fluid film is governed by the viscosity of the base oil in the lubricant; the efficacy of the solid tribofilm, which is produced as a result of sliding contact between moving parts, relies upon the effectiveness of the lubricant’s anti-wear additive (typically zinc dialkyldithiophosphate). Minimizing friction and wear continues to be a challenge, and recent efforts have focused on enhancing the anti-friction and anti-wear properties of lubricants by incorporating inorganic nanoparticles and ionic liquids. Here, we describe the in operando formation of carbon-based tribofilms via dissociative extraction from base-oil molecules on catalytically active, sliding nanometre-scale crystalline surfaces, enabling base oils to provide not only the fluid but also the solid tribofilm. We study nanocrystalline catalytic coatings composed of nitrides of either molybdenum or vanadium, containing either copper or nickel catalysts, respectively. Structurally, the resulting tribofilms are similar to diamond-like carbon. Ball-on-disk tests at contact pressures of 1.3 gigapascals reveal that these tribofilms nearly eliminate wear, and provide lower friction than tribofilms formed with zinc dialkyldithiophosphate. Reactive and ab initio molecular-dynamics simulations show that the catalytic action of the coatings facilitates dehydrogenation of linear olefins in the lubricating oil and random scission of their carbon-carbon backbones; the products recombine to nucleate and grow a compact, amorphous lubricating tribofilm.

Dynamic friction and wear of a solid film lubricant during radiation exposure in a nuclear reactor

NASA Technical Reports Server (NTRS)

Jacobson, T. P.

1972-01-01

The effect of nuclear reactor radiation on the performance of a solid film lubricant was studied. The film consisted of molybdenum disulfide and graphite in a sodium silicate binder. Radiation levels of fast neutrons (E or = 1 MeV) were fluxed up to 3.5 times 10 to the 12th power n/sq cm-sec (intensity) and fluences up to 2 times 10 to the 18th power n/sq cm (total exposure). Coating wear lives were much shorter and friction coefficients higher in a high flux region of the reactor than in a low flux region. The amount of total exposure did not affect lubrication behavior as severely as the radiation intensity during sliding.

Effect of triangular texture on the tribological performance of die steel with TiN coatings under lubricated sliding condition

NASA Astrophysics Data System (ADS)

Chen, Ping; Xiang, Xin; Shao, Tianmin; La, Yingqian; Li, Junling

2016-12-01

The friction and wear of stamping die surface can affect the service life of stamping die and the quality of stamping products. Surface texturing and surface coating have been widely used to improve the tribological performance of mechanical components. This study experimentally investigated the effect of triangular surface texture on the friction and wear properties of the die steel substrate with TiN coatings under oil lubrication. TiN coatings were deposited on a die steel (50Cr) substrate through a multi-arc ion deposition system, and then triangular surface texturing was fabricated by a laser surface texturing. The friction and wear test was conducted by a UMT-3 pin-on-disk tribometer under different sliding speeds and different applied loads, respectively. The adhesion test was performed to evaluate the effectiveness of triangular texturing on the interfacial bonding strength between the TiN coating and the die steel substrate. Results show that the combination method of surface texturing process and surface coating process has excellent tribological properties (the lowest frictional coefficient and wear volume), compared with the single texturing process or the single coating process. The tribological performance is improved resulting from the high hardness and low elastic modulus of TiN coatings, and the generation of hydrodynamic pressure, function of micro-trap for wear debris and micro-reservoirs for lubricating oil of the triangular surface texture. In addition, the coating bonding strength of the texturing sample is 3.63 MPa, higher than that of the single coating sample (3.48 MPa), but the mechanisms remain to be further researched.

The Evaluation of a Modified Chrome Oxide Based High Temperature Solid Lubricant Coating for Foil Gas Bearings

NASA Technical Reports Server (NTRS)

DellaCorte, Chris

1998-01-01

This paper describes the friction and wear performance of PS304, a modified chrome oxide based coating, for foil gas bearings. PS304 contains 60 wt% NiCr binder, 20 wt% Cr2O3 hardener, and 10 wt% each Ag, and BaF2/CaF2 lubricants. For evaluation, the coating is plasma spray deposited onto test journals which are slid against a superalloy partial arc foil bearing. The test load was 10 KPa (1.5 psi) and the bearings were run under start/stop cyclic conditions. The data show good wear performance of the bearing, especially at temperatures above 25 deg. C. Bearing friction was moderate (micron approx. or equal to 0.4) over the entire temperature range. Based upon the results obtained, the PS304 coating has promise for high temperature, oil-free turbomachinery applications.

Lubricating Properties of Some Bonded Fluoride and Oxide Coatings for Temperature to 1500 F

NASA Technical Reports Server (NTRS)

Sliney, Harold E.

1960-01-01

The lubricating properties of some experimental ceramic coatings, diffusion-bonded fluoride coatings, and ceramic-bonded fluoride coatings were determined. The experiments were conducted in an air atmosphere at a sliding velocity of 430 feet per minute and at temperatures from 75 to 1500 F. Several ceramic coatings provided substantial reductions in friction coefficient and rider wear (compared with the unlubricated metals). For example, a cobaltous oxide (CoO) base coating gave friction coefficients of 0.24 to 0.36 within the temperature range of 75 to 1400 F; serious galling and welding of the metal surfaces were prevented. The friction coefficients were higher than the arbitrary maximum (0.2) usually considered for effective boundary lubrication. However, when a moderately high friction coefficient can be tolerated, this type of coating may be a useful antiwear composition. Diffusion-bonded calcium fluoride (CaF2) on Haynes Stellite 21 and on Inconel X gave friction coefficients of 0.1 to 0.2 at 1500 F. Endurance life was dependent on the thermal history of the coating; life improved with increased exposure time at elevated temperatures prior to running. Promising results were obtained with ceramic-bonded CaF2 on Inconel X. Effective lubrication and good adherence were obtained with a 3 to 1 ratio of CaF2 to ceramic. A very thin sintered and burnished film of CaF2 applied to the surface of this coating further improved lubrication, particularly above 1350 F. The friction coefficient was 0.2 at 500 F and decreased with increasing temperature to 0.06-at 1500 F. It was 0.25 at 75 F and 0.22 at 250 F.

The thermal conductance of solid-lubricated bearings at cryogenic temperatures in vacuum

NASA Technical Reports Server (NTRS)

Anderson, M. J.

1996-01-01

The thermal conductance of Hertzian contacts is of great importance to cryogenic spacecraft mechanisms such as the Infra-Red Space Observatory (ISO) and the Far Infra-Red Space Telescope (FIRST). At cryogenic temperatures, cooling of mechanism shafts and associated components occurs via conduction through the bearings. When fluid lubricants are cooled below their pour points, they no longer lubricate effectively, and it is necessary to use low shear strength solid lubricants. Currently, only very limited low temperature data exists on the thermal conductance of Hertzian contacts in both unlubricated and lubricated conditions. This paper reports on measurements of thermal conductance made on stationary ball bearings under cryo-vacuum conditions. Quantitative data is provided to support the development of computer models predicting the thermal conductance of Hertzian contacts and solid lubricants at cryogenic temperatures.

Atomistic study of ternary oxides as high-temperature solid lubricants

NASA Astrophysics Data System (ADS)

Gao, Hongyu

Friction and wear are important tribological phenomena tightly associated with the performance of tribological components/systems such as bearings and cutting machines. In the process of contact and sliding, friction and wear lead to energy loss, and high friction and wear typically result in shortened service lifetime. To reduce friction and wear, solid lubricants are generally used under conditions where traditional liquid lubricants cannot be applied. However, it is challenging to maintain the functionality of those materials when the working environment becomes severe. For instance, at elevated temperatures (i.e., above 400 °C), most traditional solid lubricants, such as MoS2 and graphite, will easily oxidize or lose lubricity due to irreversible chemical changes. For such conditions, it is necessary to identify materials that can remain thermally stable as well as lubricious over a wide range of temperatures. Among the currently available high-temperature solid lubricants, Ag-based ternary metal oxides have recently drawn attention due to their low friction and ability to resist oxidation. A recent experimental study showed that the Ag-Ta-O ternary exhibited an extremely low coefficient of friction (0.06) at 750 °C. To fully uncover the lubricious nature of this material as a high-temperature solid lubricant, a series of tribological investigations were carried out based on one promising candidate - silver tantalate (AgTaO3). The study was then extended to alternative materials, Cu-Ta-O ternaries, to accommodate a variety of application requirements. We aimed to understand, at an atomic level, the effects of physical and chemical properties on the thermal, mechanical and tribological behavior of these materials at high temperatures. Furthermore, we investigated potassium chloride films on a clean iron surface as a representative boundary lubricating system in a nonextreme environment. This investigation complemented the study of Ag/Cu-Ta-O and enhanced the

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.

Optimization of Friction and Wear Properties of Electroless Ni-P Coatings Under Lubrication Using Grey Fuzzy Logic

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Arkadeb; Duari, Santanu; Barman, Tapan Kumar; Sahoo, Prasanta

2017-10-01

The present study aims to evaluate the friction and wear behaviour of electroless Ni-P coatings sliding against hardened chromium coated steel under lubrication. Tribological tests are carried out on a block-on-roller configuration multi tribotester. The effect of variation of applied normal load, rotation speed of the counterface roller and test duration on the coefficient of friction and wear depth is analyzed using Taguchi's robust design philosophy and design of experiments. Optimal setting of the tribo-testing parameters is evaluated using a hybrid grey fuzzy reasoning analysis in a quest to achieve optimal tribological performance of the coatings under lubrication. Analysis of variance reveals the highest contribution by applied normal load in controlling the tribological behaviour under lubrication. Whereas the interaction effect of load and time is also seen to cast a significant effect. Surface morphology studies reveal a typical nodular structure of the deposits. The coatings are seen to be amorphous in its as-deposited condition which becomes crystalline on heat treatment. Further, the synergistic effects of test parameters, microstructure of the coatings, lubrication, etc. on the tribological behaviour are assessed.

Tribological and Mechanical Behaviors of Polyamide 6/Glass Fiber Composite Filled with Various Solid Lubricants

PubMed Central

Li, Duxin; Xie, Ying; Li, Wenjuan; You, Yilan; Deng, Xin

2013-01-01

The effects of polytetrafluoroethylene (PTFE), graphite, ultrahigh molecular weight polyethylene (UHMWPE), and their compounds on mechanical and tribological properties of glass-fiber-reinforced polyamide 6 (PA6/GF) were studied. The polymeric materials were blended using twin-screw extruder and subsequently injection molded for test samples. Mechanical properties were investigated in terms of hardness, tensile strength, and impact strength. Friction and wear experiments were run under ambient conditions at a rotating speed of 200 rpm and load of 100 N. The morphologies of the worn surfaces were also observed with scanning electron microscope. The results showed that graphite could increase the tensile strength of PA6/GF-15 composite, but the material became soft. Graphite/UHMWPE complex solid lubricants were effective in increasing the already high impact strength of PA6/GF-15 composite. 5% PTFE gave the maximum reduction in the coefficient of friction. However, PTFE/UHMWPE complex solid lubricants were the best choice for improving both friction and wear behaviors due to the lower friction coefficient and mass wear rate. Moreover, the worn surface of PA6 composites revealed that adhesive wear, abrasive wear, and fatigue wear occurred in this study. PMID:23766687

A Review of Tribological Coatings for Control Drive Mechanisms in Space Reactors

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

CJ Larkin; JD Edington; BJ Close

2006-02-21

Tribological coatings must provide lubrication for moving components of the control drive mechanism for a space reactor and prevent seizing due to friction or diffusion welding to provide highly reliable and precise control of reflector position over the mission lifetime. Several coatings were evaluated based on tribological performance at elevated temperatures and in ultrahigh vacuum environments. Candidates with proven performance in the anticipated environment are limited primarily to disulfide materials. Irradiation data for these coatings is nonexistent. Compatibility issues between coating materials and structural components may require the use of barrier layers between the solid lubricant and structural components tomore » prevent deleterious interactions. It would be advisable to consider possible lubricant interactions prior to down-selection of structural materials. A battery of tests was proposed to provide the necessary data for eventual solid lubricant/coating selection.« less

Protective Coatings

NASA Technical Reports Server (NTRS)

1980-01-01

General Magnaplate Corporation's pharmaceutical machine is used in the industry for high speed pressing of pills and capsules. Machine is automatic system for molding glycerine suppositories. These machines are typical of many types of drug production and packaging equipment whose metal parts are treated with space spinoff coatings that promote general machine efficiency and contribute to compliance with stringent federal sanitation codes for pharmaceutical manufacture. Collectively known as "synergistic" coatings, these dry lubricants are bonded to a variety of metals to form an extremely hard slippery surface with long lasting self lubrication. The coatings offer multiple advantages; they cannot chip, peel or be rubbed off. They protect machine parts from corrosion and wear longer, lowering maintenance cost and reduce undesired heat caused by power-robbing friction.

Dynamic stability and slider-lubricant interactions in hard disk drives

NASA Astrophysics Data System (ADS)

Ambekar, Rohit Pradeep

2007-12-01

Hard disk drives (HDD) have played a significant role in the current information age and have become the backbone of storage. The soaring demand for mass data storage drives the necessity for increasing capacity of the drives and hence the areal density on the disks as well as the reliability of the HDD. To achieve greater areal density in hard disk drives, the flying height of the airbearing slider continually decreases. Different proximity forces and interactions influence the air bearing slider resulting in fly height modulation and instability. This poses several challenges to increasing the areal density (current goal is 2Tb/in.2) as well as making the head-disk interface (HDI) more reliable. Identifying and characterizing these forces or interactions has become important for achieving a stable fly height at proximity and realizing the goals of areal density and reliability. Several proximity forces or interactions influencing the slider are identified through the study of touchdown-takeoff hysteresis. Slider-lubricant interaction which causes meniscus force between the slider and disk as well as airbearing surface contamination seems to be the most important factor affecting stability and reliability at proximity. In addition, intermolecular forces and disk topography are identified as important factors. Disk-to-slider lubricant transfer leads to lubricant pickup on the slider and also causes depletion of lubricant on the disk, affecting stability and reliability of the HDI. Experimental and numerical investigation as well as a parametric study of the process of lubricant transfer has been done using a half-delubed disk. In the first part of this parametric study, dependence on the disk lubricant thickness, lubricant type and slider ABS design has been investigated. It is concluded that the lubricant transfer can occur without slider-disk contact and there can be more than one timescale associated with the transfer. Further, the transfer increases non

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings

PubMed Central

Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

2016-01-01

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings. PMID:26924136

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings.

PubMed

Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

2016-02-29

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

Co-electrodeposition of hard Ni-W/diamond nanocomposite coatings

NASA Astrophysics Data System (ADS)

Zhang, Xinyu; Qin, Jiaqian; Das, Malay Kumar; Hao, Ruru; Zhong, Hua; Thueploy, Adisak; Limpanart, Sarintorn; Boonyongmaneerat, Yuttanant; Ma, Mingzhen; Liu, Riping

2016-02-01

Electroplated hard chrome coating is widely used as a wear resistant coating to prolong the life of mechanical components. However, the electroplating process generates hexavalent chromium ion which is known carcinogen. Hence, there is a major effort throughout the electroplating industry to replace hard chrome coating. Composite coating has been identified as suitable materials for replacement of hard chrome coating, while deposition coating prepared using traditional co-deposition techniques have relatively low particles content, but the content of particles incorporated into a coating may fundamentally affect its properties. In the present work, Ni-W/diamond composite coatings were prepared by sediment co-electrodeposition from Ni-W plating bath, containing suspended diamond particles. This study indicates that higher diamond contents could be successfully co-deposited and uniformly distributed in the Ni-W alloy matrix. The maximum hardness of Ni-W/diamond composite coatings is found to be 2249 ± 23 Hv due to the highest diamond content of 64 wt.%. The hardness could be further enhanced up to 2647 ± 25 Hv with heat treatment at 873 K for 1 h in Ar gas, which is comparable to hard chrome coatings. Moreover, the addition of diamond particles could significantly enhance the wear resistance of the coatings.

Friction and lubrication modelling in sheet metal forming: Influence of lubrication amount, tool roughness and sheet coating on product quality

NASA Astrophysics Data System (ADS)

Hol, J.; Wiebenga, J. H.; Carleer, B.

2017-09-01

In the stamping of automotive parts, friction and lubrication play a key role in achieving high quality products. In the development process of new automotive parts, it is therefore crucial to accurately account for these effects in sheet metal forming simulations. This paper presents a selection of results considering friction and lubrication modelling in sheet metal forming simulations of a front fender product. For varying lubrication conditions, the front fender can either show wrinkling or fractures. The front fender is modelled using different lubrication amounts, tool roughness’s and sheet coatings to show the strong influence of friction on both part quality and the overall production stability. For this purpose, the TriboForm software is used in combination with the AutoForm software. The results demonstrate that the TriboForm software enables the simulation of friction behaviour for varying lubrication conditions, i.e. resulting in a generally applicable approach for friction characterization under industrial sheet metal forming process conditions.

Liquid Lubricants for Spacecraft Applications

NASA Astrophysics Data System (ADS)

Gill, S.; Rowntree, A.

Liquid lubricants used for spacecraft have advantages over solid lubricants but there are also disadvantages to consider. The challenge is to ensure that the liquid lubricant does not disappear from the mechanism by evaporation or creep. Lubricants can be used as fluids or formulated as greases. The liquids can be highly refined hydrocarbons, PAOs, silicones, polyol esters (POEs), multiply alkylated cycloparaffins, (MACs) or various perfluoropolyethers (PFPEs). Greases are made from these liquids using thickeners such as lithium, calcium or sodium soaps, PTFE, graphite or lead. Operational temperatures range from - 45°C to over 100°C. Low vapour pressures are crucial, below 10-8 mbar at 20°C and total weight loss must be <1% for general applications, <0.1% for optical applications. 'Surface creep rates' must be low, temperature gradients and surface Ra are important factors. The wear rates for standard tests using different lubricants vary over several orders of magnitude for different lubricants, surface coatings and rpm. Unexpected effects, such as PTFE 'plating out' at low rpm, occur. The main issues are to prevent the lubricant escaping from working areas and to protect it from degradation by chemical reactions or radiation.

Bonded Lubricants

NASA Technical Reports Server (NTRS)

1977-01-01

Another spinoff to the food processing industry involves a dry lubricant developed by General Magnaplate Corp. of Linden, N.J. Used in such spacecraft as Apollo, Skylab and Viking, the lubricant is a coating bonded to metal surfaces providing permanent lubrication and corrosion resistance. The coating lengthens equipment life and permits machinery to be operated at greater speed, thus increasing productivity and reducing costs. Bonded lubricants are used in scores of commercia1 applications. They have proved particularly valuable to food processing firms because, while increasing production efficiency, they also help meet the stringent USDA sanitation codes for food-handling equipment. For example, a cookie manufacturer plagued production interruptions because sticky batter was clogging the cookie molds had the brass molds coated to solve the problem. Similarly, a pasta producer faced USDA action on a sanitation violation because dough was clinging to an automatic ravioli-forming machine; use of the anti-stick coating on the steel forming plates solved the dual problem of sanitation deficiency and production line downtime.

Lubrication handbook

NASA Technical Reports Server (NTRS)

Campbell, M. E.; Thompson, M. B.

1973-01-01

Information on lubricants from government reports, military specifications, qualified parts lists, and suppliers of commercial lubricants has been consolidated in one source. Handbook includes data on chemical and physical properties of solid, bonded solid, and liquid lubricants; dispersions and composites; and greases, oils, and hydraulic fluids.

Wear of tin coating and Al-Si alloy substrate against carburized steel under mixed lubrication

NASA Astrophysics Data System (ADS)

Wang, Q.; Cheng, H. S.; Fine, M. E.

1994-04-01

Tin coatings on Al-Si alloys are widely used in the automotive industries. The soft tin coating and the harder substrate alloy form a tribological system with the advantages of low friction and reasonably high load-bearing capacity. Wear tests of tin coated Al-Si Z332 alloy in conformal contact against carburized 1016 steel have been carried out under mixed lubrications with SAE 10W30 oil to study the wear mechanisms. Two major wear mechanisms, uniform wear of the tin coating due to micro-plowing and spall pitting related to the substrate are found to contribute to the bearing material loss when the fluid lubrication film is relatively thick (Lambda about 1.6). Under conditions of thinner films (Lambda approximately = 0.8), some local coating debonding occurs. The pitting and local coating debounding are closely related to fracture in the substrate. The bonding between silicon and tin seems to be weaker than between aluminum and tin. During wear, oxidation occurs.

Solid Lubricant For Alumina

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher; Pepper, Stephen V.; Honecy, Frank S.

1993-01-01

Outer layer of silver lubricates, while intermediate layer of titanium ensures adhesion. Lubricating outer films of silver deposited on thin intermediate films of titanium on alumina substrates found to reduce sliding friction and wear. Films provide effective lubrication for ceramic seals, bearings, and other hot sliding components in advanced high-temperature engines.

Analysis of Hard Thin Film Coating

NASA Technical Reports Server (NTRS)

Shen, Dashen

1998-01-01

Marshall Space Flight Center (MSFC) is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using Electron Cyclotron Resonance Chemical Vapor Deposition (ECRCVD) to deposit hard thin film on stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

Analysis of Hard Thin Film Coating

NASA Technical Reports Server (NTRS)

Shen, Dashen

1998-01-01

MSFC is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using electron cyclotron resonance chemical vapor deposition (ECRCVD) to deposit hard thin film an stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

Impact of Nanometer Graphite Addition on the Anti-deliquescence and Tribological Properties of Ni/MoS2 Lubricating Coating

NASA Astrophysics Data System (ADS)

Zhang, S.; Li, G. L.; Wang, H. D.; Xu, B. S.; Ma, G. Z.

In order to improve the long-standing problem of MoS2 coating that lubrication performance drop dramatic after storage in humid air, using nano-composite electro brush plating technology and Ni/MoS2-C combination coating with thinness of 100 μm was succeed deposited on GCr15 substrate. Microstructure, surface morphology and elements of this composite coating were analyzed using SEM, XPS and TEM while phase structure was tested by XRD. The tribological properties of this composite coating were tested by MSTS-1; Test the preceding tribological properties of Ni/MoS2-C composite coatings to the pure Ni/MoS2 after different period storage at room temperature and 100% relative humidity atmosphere of 12 h, 24 h, and 48 h as well as the element of the chemical changes. Research shows that there is a small amount of MoS2 in pure MoS2 coatings behind a 12 hours storage in humid air became MoO3 and the tribological performance decreased significantly followed, in the same conditions composite coating with nanometer graphite addition get a preferably tribological properties while the hardness of this coating was improved by the nanometer graphite addition and combination plating showed a well duration tribological properties as a result.

Evaluation of PS 212 Coatings Under Boundary Lubrication Conditions with an Ester-based Oil to 300 C

NASA Technical Reports Server (NTRS)

Sliney, Harold E.; Loomis, William R.; Dellacorte, Christopher

1994-01-01

High friction and wear of turbine engine components occur during high temperature excursions above the oxidation threshold of the liquid lubricant. This paper reports on research to study the use of a high temperature self lubricating coating, PS 212 for back-up lubrication in the event of failure of the liquid lubricant. Pin on disk tests were performed under dry and boundary-lubricated conditions at disk temperatures up to 300 C. The liquid lubricant was a formulated polyol ester qualified under MIL L-23699. At test temperatures above the oil's thermal degradation level, the use of PS 212 reduced wear, providing a back-up lubricant effect.

Wear behavior of electroless Ni-P-W coating under lubricated condition - a Taguchi based approach

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Arkadeb; Duari, Santanu; Barman, Tapan Kumar; Sahoo, Prasanta

2016-09-01

The present study aims to investigate the tribological behavior of electroless Ni-P-W coating under engine oil lubricated condition to ascertain its suitability in automotive applications. Coating is deposited onto mild steel specimens by the electroless method. The experiments are carried out on a pin - on - disc type tribo tester under lubrication. Three tribotesting parameters namely the applied normal load, sliding speed and sliding duration are varied at their three levels and their effects on the wear depth of the deposits are studied. The experiments are carried out based on the combinations available in Taguchi's L27 orthogonal array (OA). Optimization of the tribo-testing parameters is carried out using Taguchi's S/N ratio method to minimize the wear depth. Analysis of variance carried out at a confidence level of 99% indicates that the sliding speed is the most significant parameter in controlling the wear behavior of the deposits. Coating characterization is done using scanning electron microscope, energy dispersive X-ray analysis and X-ray diffraction techniques. It is seen that the wear mechanism under lubricated condition is abrasive in nature.

Superhard self-lubricating AlMgB14 films for microelectromechanical devices

NASA Astrophysics Data System (ADS)

Tian, Y.; Bastawros, A. F.; Lo, C. C. H.; Constant, A. P.; Russell, A. M.; Cook, B. A.

2003-10-01

Performance and reliability of microelectromechanical system (MEMS) components can be enhanced dramatically through the incorporation of protective thin-film coatings. Current-generation MEMS devices prepared by the lithographie-galvanoformung-abformung (LIGA) technique employ transition metals such as Ni, Cu, Fe, or alloys thereof, and hence lack stability in oxidizing, corrosive, and/or high-temperature environments. Fabrication of a superhard self-lubricating coating based on a ternary boride compound AlMgB14 described in this letter has great potential in protective coating technology for LIGA microdevices. Nanoindentation tests show that the hardness of AlMgB14 films prepared by pulsed laser deposition ranges from 45 GPa to 51 GPa, when deposited at room temperature and 573 K, respectively. Extremely low friction coefficients of 0.04-0.05, which are thought to result from a self-lubricating effect, have also been confirmed by nanoscratch tests on the AlMgB14 films. Transmission electron microscopy studies show that the as-deposited films are amorphous, regardless of substrate temperature; however, analysis of Fourier transform infrared spectra suggests that the higher substrate temperature facilitates the formation of the B12 icosahedral framework, therefore leading to the higher hardness.

Investigating critical effects of variegated lubricants, glidants and hydrophilic additives on lag time of press coated ethylcellulose tablets.

PubMed

Patadia, Riddhish; Vora, Chintan; Mittal, Karan; Mashru, Rajashree

2016-01-01

The research envisaged focuses on vital impacts of variegated lubricants, glidants and hydrophilic additives on lag time of press coated ethylcellulose (EC) tablets using prednisone as a model drug. Several lubricants and glidants such as magnesium stearate, colloidal SiO2, sodium stearyl fumarate, talc, stearic acid, polyethylene glycol (6000) and glyceryl behenate were investigated to understand their effects on lag time by changing their concentrations in outer coat. Further, the effects of hydrophilic additives on lag time were examined for hydroxypropylmethylcellulose (E5), hydroxypropylcellulose (EF and SSL), povidone (K30), copovidone, polyethylene glycol (4000), lactose and mannitol. In vitro drug release testing revealed that each selected lubricant/glidant, if present even at concentration of 0.25% w/w, significantly reduced the lag time of press coated tablets. Specifically, colloidal SiO2 and/or magnesium stearate were detrimental while other lubricants/glidants were relatively less injurious. Among hydrophilic additives, freely water soluble fillers had utmost influence in lag time, whereas, comparatively less impact was observed with polymeric binders. Concisely, glidant and lubricant should be chosen to have minimal impact on lag time and further judicious selection of hydrophilic additives should be exercised for modulating lag time of pulsatile release formulations.

Spacecraft materials guide. [including: encapsulants and conformal coatings; optical materials; lubrication; and, bonding and joining processes

NASA Technical Reports Server (NTRS)

Staugaitis, C. L. (Editor)

1975-01-01

Materials which have demonstrated their suitability for space application are summarized. Common, recurring problems in encapsulants and conformal coatings, optical materials, lubrication, and bonding and joining are noted. The subjects discussed include: low density and syntactic foams, electrical encapsulants; optical glasses, interference filter, mirrors; oils, greases, lamillar lubricants; and, soldering and brazing processes.

Start-stop testing of two self-acting air-lubricated spiral groove thrust bearing coatings

NASA Technical Reports Server (NTRS)

Dunfee, J. D.; Shapiro, W.

1974-01-01

Start-stop tests were conducted on air-lubricated spiral-groove thrust bearings. Application of a matrix-bonded molybdenum disulfide (MoS2) coating over a porous chrome oxide coating resulted in significantly lower friction, compared to bearings coated with chrome oxide only. The MoS2 coated bearing sustained 15,000 start-stop cycles at a maximum of 3600 rpm. Each cycle was 15 seconds on, 30 seconds off. The chrome oxide coated bearing failed by local welding after 2030 cycles. Both types of coatings exhibited early failures under higher thrust loads when operating films were insufficient to sustain the load without overheating.

Fullerene (C60) films for solid lubrication

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

Bhushan, B.; Gupta, B.K.; Van Cleef, G.W.

1993-10-01

The advent of techniques for producing gram quantities of a new form of stable, pure, solid carbon, designated as fullerene, opens a profusion of possibilities to be explored in many disciplines including tribology. Fullerenes take the form of hollow geodesic domes, which are formed from a network of pentagons and hexagons with covalently bonded carbon atoms. The C60 molecule has the highest possible symmetry (icosahedral) and assumes the shape of a soccer ball. At room temperature, fullerene molecules pack in an fcc lattice bonded with weak van der Waals attractions. Fullerenes can be dissolved in solvents such as toluene andmore » benzene and are easily sublimed. The low surface energy, high chemical stability, spherical shape, weak intermolecular bonding, and high load bearing capacity of C60 molecules offer potential for various mechanical and tribological applications. This paper describes the crystal structure and properties of fullerenes and proposes a mechanism for self-lubricating action. Sublimed films of C60 have been produced and friction and wear performance of these films in various operating environments are the subject of this paper. The results of this study indicate that C60, owing to its unique crystal structure and bonding, may be a promising solid lubricant. 31 refs.« less

Candidate Coatings and Dry Traction Drives for Planetary Vehicles

NASA Technical Reports Server (NTRS)

Fusaro, Robert; Oswald, Fred B.

2002-01-01

Robert Fusaro and Fred Oswald of the Mechanical Components Branch discussed 'Candidate Coatings and Dry Traction Drives for Planetary Vehicles'. Vehicles to be designed for exploration of planets and moons of the solar system will require reliable mechanical drives to operate efficiently. Long-term operation of these drives will be challenging because of extreme operating conditions. These extreme conditions include: very high and/or very cold temperatures, wide temperature ranges, dust, vacuum or low-pressure atmospheres, and corrosive environments. Most drives used on Earth involve oil-lubricated gears. However, due to the extreme conditions on planetary surfaces, it may not be advisable or even possible to use oil lubrication. Unfortunately, solid lubricants do not work well when applied to gears because of the high contact stress conditions and large sliding motion between the teeth, which cause wear and limit life. We believe traction drives will provide an attractive alternative to gear drives. Traction drives are composed of rollers that provide geometry more conducive to solid lubrication. Minimal slip occurs in this contact geometry and thus there is very low wear to the solid lubricant. The challenge for these solid-lubricated drives is finding materials or coatings that provide the required long-life while also providing high traction. We seek materials that provide low wear with high friction.

Enhanced lubricant film formation through micro-dimpled hard-on-hard artificial hip joint: An in-situ observation of dimple shape effects.

PubMed

Choudhury, Dipankar; Rebenda, David; Sasaki, Shinya; Hekrle, Pavel; Vrbka, Martin; Zou, Min

2018-05-01

This study evaluates the impact of dimple shapes on lubricant film formation in artificial hip joints. Micro-dimples with 20-50 µm lateral size and 1 ± 0.2 µm depths were fabricated on CrCoMo hip joint femoral heads using a picosecond laser. Tribological studies were performed using a pendulum hip joint simulator to apply continuous swing flexion-extension motions. The results revealed a significantly enhanced lubricant film thickness (≥ 500 nm) with micro-dimpled prosthesis heads at equilibrium position after the lubricant film has fully developed. The average lubricant film thickness of dimpled prostheses with square- and triangular-shaped dimple arrays over time is about 3.5 that of the non-dimpled prosthesis (204 nm). Remarkably, the prosthesis with square-shaped dimple arrays showed a very fast lubricant film formation reaching their peak values within 0.5 s of pendulum movement, followed by prosthesis with triangular-shaped dimple arrays with a transition period of 42.4 s. The fully developed lubricant film thicknesses (≥ 700 nm) are significantly higher than the surface roughness (≈ 25 nm) demonstrating a hydrodynamic lubrication. Hardly any scratches appeared on the post-experimental prosthesis with square-shaped dimple array and only a few scratches were found on the post-experimental prosthesis with triangular-shaped dimple arrays. Thus, prostheses with square-shaped dimple arrays could be a potential solution for durable artificial hip joints. Copyright © 2018 Elsevier Ltd. All rights reserved.

Advances in sputtered and ion plated solid film lubrication

NASA Technical Reports Server (NTRS)

Spalvins, T.

1985-01-01

The glow discharge or ion assisted vacuum deposition techniques, primarily sputtering and ion plating, have rapidly emerged and offer great potential to deposit solid lubricants. The increased energizing of these deposition processes lead to improved adherence and coherence, favorable morphological growth, higher density, and reduced residual stresses in the film. These techniques are of invaluable importance where high precision machines tribo-components require very thin, uniform lubricating films (0.2 m), which do not interface with component tolerances. The performance of sputtered MoS2 films and ion plated Au and Pb films are described in terms of film thickness, coefficient of friction, and wear lives.

Fluorine lubricated bearing technology

NASA Technical Reports Server (NTRS)

Mallaire, F. R.

1973-01-01

An experimental program was conducted to evaluate and select materials for ball bearings intended for use in liquid fluorine and/or FLOX. The ability of three different ball-separator materials, each containing nickel, to form and transfer a nickel fluoride film to provide effective lubrication at the required areas of a ball bearing operating in liquid fluorine was evaluated. In addition, solid lubrication of a ball bearing operating in liquid fluorine by either a fused fluoride coating applied to all surfaces of the ball separator or by a fluoride impregnation of porous sintered material ball separators was evaluated. Less bearing wear occurred when tests were conducted in the less reactive FLOX. Bearings fabricated from any of the materials tested would have relatively short wear lives and would require frequent replacement in a reusable engine.

Thermochemical Stability and Friction Properties of Soft Organosilica Networks for Solid Lubrication.

PubMed

Gonzalez Rodriguez, Pablo; Dral, A Petra; van den Nieuwenhuijzen, Karin J H; Lette, Walter; Schipper, Dik J; Ten Elshof, Johan E

2018-01-24

In view of their possible application as high temperature solid lubricants, the tribological and thermochemical properties of several organosilica networks were investigated over a range of temperatures between 25 and 580 °C. Organosilica networks, obtained from monomers with terminal and bridging organic groups, were synthesized by a sol-gel process. The influence of carbon content, crosslink density, rotational freedom of incorporated hydrocarbon groups, and network connectivity on the high temperature friction properties of the polymer was studied for condensed materials from silicon alkoxide precursors with terminating organic groups, i.e., methyltrimethoxysilane, propyltrimethoxysilane, diisopropyldimethoxysilane, cyclohexyltrimethoxysilane, phenyltrimethoxysilane and 4-biphenylyltriethoxysilane networks, as well as precursors with organic bridging groups between Si centers, i.e., 1,4-bis(triethoxysilyl)benzene and 4,4'-bis(triethoxysilyl)-1,1'-biphenyl. Pin-on-disc measurements were performed using all selected solid lubricants. It was found that materials obtained from phenyltrimethoxysilane and cyclohexyltrimethoxysilane precursors showed softening above 120 °C and performed best in terms of friction reduction, reaching friction coefficients as low as 0.01. This value is lower than that of graphite films (0.050 ± 0.005), a common bench mark for solid lubricants.

Thermochemical Stability and Friction Properties of Soft Organosilica Networks for Solid Lubrication

PubMed Central

Gonzalez Rodriguez, Pablo; van den Nieuwenhuijzen, Karin J. H.; Lette, Walter; Schipper, Dik J.

2018-01-01

In view of their possible application as high temperature solid lubricants, the tribological and thermochemical properties of several organosilica networks were investigated over a range of temperatures between 25 and 580 °C. Organosilica networks, obtained from monomers with terminal and bridging organic groups, were synthesized by a sol-gel process. The influence of carbon content, crosslink density, rotational freedom of incorporated hydrocarbon groups, and network connectivity on the high temperature friction properties of the polymer was studied for condensed materials from silicon alkoxide precursors with terminating organic groups, i.e., methyltrimethoxysilane, propyltrimethoxysilane, diisopropyldimethoxysilane, cyclohexyltrimethoxysilane, phenyltrimethoxysilane and 4-biphenylyltriethoxysilane networks, as well as precursors with organic bridging groups between Si centers, i.e., 1,4-bis(triethoxysilyl)benzene and 4,4′-bis(triethoxysilyl)-1,1′-biphenyl. Pin-on-disc measurements were performed using all selected solid lubricants. It was found that materials obtained from phenyltrimethoxysilane and cyclohexyltrimethoxysilane precursors showed softening above 120 °C and performed best in terms of friction reduction, reaching friction coefficients as low as 0.01. This value is lower than that of graphite films (0.050 ± 0.005), a common bench mark for solid lubricants. PMID:29364164

Lubricating coating prepared by PIIID on a forming tool

NASA Astrophysics Data System (ADS)

Martinatti, J. F.; Santos, L. V.; Durrant, S. F.; Cruz, N. C.; Rangel, E. C.

2012-06-01

In this work, the performance of a-C:H films produced by the hybrid Plasma Immersion Ion Implantation and Deposition technique as lubricating layers for a steel forming tool has been investigated. Hardened steel (AISI M2, 64 HRC) plates coated with a commercial TiN layer were used as substrates and the films were deposited in a vacuum chamber fitted with two parallel-plate electrodes. The discharges were generated in atmospheres composed of 91% C2H2 and 9% Ar by the application of radiofrequency power (13.56 MHz, 100 W) to the upper electrode while the lower one, also used as the sample holder, was biased with high voltage negative pulses (3.6 kV, 30 μs, 300 Hz). A deposition time of 840 s was used. The effects of the gas pressure, p, on thickness, molecular structure, wettability, surface morphology and topography, hardness and friction coefficient of the films were investigated. Film thickness increased from 0.3 to 0.5 μm when p was increased from 2.7 to 16.5 Pa. Generally, the films were slightly hydrophilic, with contact angles of around 84°, and the deposition decreased the roughness of the steel. A polymer-like structure was detected in high pressure depositions and an amorphous carbon structure derived from the low pressure procedures. Hardness decreased from 8.2 to 7.0 GPa with increasing p. Improvement in tribological performance was indicated by the fall in the friction coefficient from 0.5 to 0.2 as the deposition pressure was reduced. Operating at the latter value (of μ) would lead to a significant reduction in wear and hence to significant economy in diverse industrial applications.

Application of hard coatings to substrates at low temperatures

NASA Technical Reports Server (NTRS)

Sproul, William D.

1993-01-01

BIRL, the industrial research laboratory of Northwestern University, has conducted unique and innovative research, under sponsorship from the NASA Marshall Space Flight Center (MSFC), in the application of hard, wear resistant coatings to bearing steels using the high-rate reactive sputtering (HRRS) process that was pioneered by Dr. William Sproul, the principal investigator on this program. Prior to this program, Dr. Sproul had demonstrated that it is possible to apply hard coatings such as titanium nitride (TiN) to alloy steels at low temperatures via the HRRS process without changing the metallurgical properties of the steel. The NASA MSFC program at BIRL had the specific objectives to: apply TiN to 440C stainless steel without changing the metallurgical properties of the steel; prepare rolling contact fatigue (RCF) test samples coated with binary hard coatings of TiN, zirconium nitride (ZrN), hafnium nitride (HfN), chromium nitride (CrN), and molybdenum nitride (MoN), and metal coatings of copper (Cu) and gold (Au); and develop new alloyed hard coatings of titanium aluminum nitride (Ti(0.5)Al(0.5)N), titanium zirconium nitride (Ti(0.5)Zr(0.5)N), and titanium aluminum vanadium nitride.

Effect of surface condition on the formation of solid lubricating films at high temperatures

NASA Technical Reports Server (NTRS)

Hanyaloglu, Bengi; Graham, E. E.

1992-01-01

Solid films were produced on active metal or ceramic surfaces using lubricants (such as tricresyl phosphate) delivered as a vapor at high temperatures, and the lubricity of these deposits under different dynamic wear conditions was investigated. A method is described for chemically activating ceramic surfaces resulting in a surface that could promote the formation of lubricating polymeric derivative of TCP. Experiments were carried out to evaluate the wear characteristics of unlubricated cast iron and of Sialon ceramic at 25 and 280 C, and lubricated with a vapor of TCP at 280 C. It is shown that continuous vapor phase lubrication of chemically treated Sialon reduced its coefficient of friction from 0.7 to less than 0.1.

High temperature lubricating process

DOEpatents

Taylor, R.W.; Shell, T.E.

1979-10-04

It has been difficult to provide adequate lubrication for load bearing, engine components when such engines are operating in excess of about 475/sup 0/C. The present invention is a process for providing a solid lubricant on a load bearing, solid surface, such as in an engine being operated at temperatures in excess of about 475/sup 0/C. The process comprises contacting and maintaining the following steps: a gas phase is provided which includes at least one component reactable in a temperature dependent reaction to form a solid lubricant; the gas phase is contacted with the load bearing surface; the load bearing surface is maintained at a temperature which causes reaction of the gas phase component and the formation of the solid lubricant; and the solid lubricant is formed directly on the load bearing surface. The method is particularly suitable for use with ceramic engines.

High temperature lubricating process

DOEpatents

Taylor, Robert W.; Shell, Thomas E.

1982-01-01

It has been difficult to provide adaquate lubrication for load bearing, engine components when such engines are operating in excess of about 475.degree. C. The present invention is a process for providing a solid lubricant on a load bearing, solid surface (14), such as in an engine (10) being operated at temperatures in excess of about 475.degree. C. The process comprises contacting and maintaining steps. A gas phase (42) is provided which includes at least one component reactable in a temperature dependent reaction to form a solid lubricant. The gas phase is contacted with the load bearing surface. The load bearing surface is maintained at a temperature which causes reaction of the gas phase component and the formation of the solid lubricant. The solid lubricant is formed directly on the load bearing surface. The method is particularly suitable for use with ceramic engines.

Elastohydrodynamic lubrication of elliptical contacts

NASA Technical Reports Server (NTRS)

Hamrock, B. J.

1981-01-01

The determination of the minimum film thickness within contact is considered for both fully flooded and starved conditions. A fully flooded conjunction is one in which the film thickness is not significantly changed when the amount of lubricant is increased. The fully flooded results presented show the influence of contact geometry on minimum film thickness as expressed by the ellipticity parameter and the dimensionless speed, load, and materials parameters. These results are applied to materials of high elastic modulus (hard EHL), such as metal, and to materials of low elastic modulus(soft EHL), such as rubber. In addition to the film thickness equations that are developed, contour plots of pressure and film thickness are given which show the essential features of elastohydrodynamically lubricated conjunctions. The crescent shaped region of minimum film thickness, with its side lobes in which the separation between the solids is a minimum, clearly emerges in the numerical solutions. In addition to the 3 presented for the fully flooded results, 15 more cases are used for hard EHL contacts and 18 cases are used for soft EHL contacts in a theoretical study of the influence of lubricant starvation on film thickness and pressure. From the starved results for both hard and soft EHL contacts, a simple and important dimensionless inlet boundary distance is specified. This inlet boundary distance defines whether a fully flooded or a starved condition exists in the contact. Contour plots of pressure and film thickness in and around the contact are shown for conditions.

Vickers indentation hardness of stoichiometric and reduced single crystal TiO2 (rutile) from 25 to 800 C

NASA Technical Reports Server (NTRS)

Dellacorte, Christopher; Deadmore, Daniel L.

1993-01-01

The indentation microhardness of stoichiometric and reduced single crystal rutile (TiO2) from 25 to 800 C is presented in this paper. The results serve two main purposes. One is to assess the effect of rutile's stoichiometry on its hardness. The other is to test recently suggested theory on solid lubrication with sub Stoichiometric rutile in an effort to better understand shear controlled phenomenon. Microhardness was measured using a Vickers diamond indentor on both vacuum and hydrogen reduced single crystal rutile from 25 to 800 C. The results indicate that stoichiometry and temperature have a pronounced effect on rutile's hardness. The measured effects lend support to theory on solid lubrication by enhanced crystallographic slip and suggest that solid lubricant materials may be produced by careful atomic level tailoring (stoichiometry control).

100% Solids Polyurethane Sequestration Coating

DTIC Science & Technology

2014-04-11

Distribution Unlimited 100% Solids Polyurethane Sequestration Coating The views, opinions and/or findings contained in this report are those of the...Papers published in non peer-reviewed journals: 100% Solids Polyurethane Sequestration Coating Report Title Report developed under Topic #CBD13-101...Final Technical Report Contract #: W911NF-13-P-0010 Proposal #: 63958CHSB1 Project: 100% Solids Polyurethane Sequestration Coating

Coating of plasma polymerized film

NASA Technical Reports Server (NTRS)

Morita, S.; Ishibashi, S.

1980-01-01

Plasma polymerized thin film coating and the use of other coatings is suggested for passivation film, thin film used for conducting light, and solid body lubrication film of dielectrics of ultra insulators for electrical conduction, electron accessories, etc. The special features of flow discharge development and the polymerized film growth mechanism are discussed.

Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative

DTIC Science & Technology

2014-11-01

1 ASETSDefense 2014 Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative Ruben A. Prado, CEF...COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Electrodeposition of Nanocrystalline Cobalt Phosphorous Coatings as a Hard Chrome Alternative...coatings as a Hard Chrome (EHC) electroplating alternative for DoD manufacturing and repair. – Fully define deposition parameters and properties

Relationship Between Crystalline Structure and Hardness of Ti-Si-N-O Coatings Fabricated by dc Sputtering

NASA Astrophysics Data System (ADS)

García-González, Leandro; Hernández-Torres, Julián; Mendoza-Barrera, Claudia; Meléndez-Lira, Miguel; García-Ramírez, Pedro J.; Martínez-Castillo, Jaime; Sauceda, Ángel; Herrera-May, Agustin L.; Muñoz Saldaña, Juan; Espinoza-Beltrán, Francisco J.

2008-08-01

Ti-Si-N-O coatings were deposited on AISI D2 tool steel and silicon substrates by dc reactive magnetron co-sputtering using a target of Ti-Si with a constant area ratio of 0.2. The substrate temperature was 400 °C and reactive atmosphere of nitrogen and argon. For all samples, argon flow was maintained constant at 25 sccm, while the flow of the nitrogen was varied to analyze the structural changes related to chemical composition and resistivity. According to results obtained by x-ray diffraction and stoichiometry calculations by x-ray energy dispersive spectroscopy the Ti-Si-N-O coatings contain two solid solutions. The higher crystalline part corresponds to titanium oxynitrure. Hardness tests on the coatings were carried out using the indentation work model and the hardness value was determined. Finally, the values of hardness were corroborated by nanoindentation test, and values of Young’s modulus and elastic recovery were discussed. We concluded that F2TSN sample ( F Ar = 25 sccm, F N = 5 sccm, P = 200 W, and P W = 8.9 × 10-3 mbar) presented the greatest hardness and the lowest resistivity values, due to its preferential crystalline orientation.

Evaluation of risk and benefit in thermal effusivity sensor for monitoring lubrication process in pharmaceutical product manufacturing.

PubMed

Uchiyama, Jumpei; Kato, Yoshiteru; Uemoto, Yoshifumi

2014-08-01

In the process design of tablet manufacturing, understanding and control of the lubrication process is important from various viewpoints. A detailed analysis of thermal effusivity data in the lubrication process was conducted in this study. In addition, we evaluated the risk and benefit in the lubrication process by a detailed investigation. It was found that monitoring of thermal effusivity detected mainly the physical change of bulk density, which was changed by dispersal of the lubricant and the coating powder particle by the lubricant. The monitoring of thermal effusivity was almost the monitoring of bulk density, thermal effusivity could have a high correlation with tablet hardness. Moreover, as thermal effusivity sensor could detect not only the change of the conventional bulk density but also the fractional change of thermal conductivity and thermal capacity, two-phase progress of lubrication process could be revealed. However, each contribution of density, thermal conductivity, or heat capacity to thermal effusivity has the risk of fluctuation by formulation. After carefully considering the change factor with the risk to be changed by formulation, thermal effusivity sensor can be a useful tool for monitoring as process analytical technology, estimating tablet hardness and investigating the detailed mechanism of the lubrication process.

Investigation of metallurgical coatings for automotive applications

NASA Astrophysics Data System (ADS)

Su, Jun Feng

Metallurgical coatings have been widely used in the automotive industry from component machining, engine daily running to body decoration due to their high hardness, wear resistance, corrosion resistance and low friction coefficient. With high demands in energy saving, weight reduction and limiting environmental impact, the use of new materials such as light Aluminum/magnesium alloys with high strength-weight ratio for engine block and advanced high-strength steel (AHSS) with better performance in crash energy management for die stamping, are increasing. However, challenges are emerging when these new materials are applied such as the wear of the relative soft light alloys and machining tools for hard AHSS. The protective metallurgical coatings are the best option to profit from these new materials' advantages without altering largely in mass production equipments, machinery, tools and human labor. In this dissertation, a plasma electrolytic oxidation (PEO) coating processing on aluminum alloys was introduced in engine cylinder bores to resist wear and corrosion. The tribological behavior of the PEO coatings under boundary and starve lubrication conditions was studied experimentally and numerically for the first time. Experimental results of the PEO coating demonstrated prominent wear resistance and low friction, taking into account the extreme working conditions. The numerical elastohydrodynamic lubrication (EHL) and asperity contact based tribological study also showed a promising approach on designing low friction and high wear resistant PEO coatings. Other than the fabrication of the new coatings, a novel coating evaluation methodology, namely, inclined impact sliding tester was presented in the second part of this dissertation. This methodology has been developed and applied in testing and analyzing physical vapor deposition (PVD)/ chemical vapor deposition (CVD)/PEO coatings. Failure mechanisms of these common metallurgical hard coatings were systematically

Pulsed Plasma Lubrication Device and Method

NASA Technical Reports Server (NTRS)

Hofer, Richard R. (Inventor); Bickler, Donald B. (Inventor); D'Agostino, Saverio A. (Inventor)

2016-01-01

Disclosed herein is a lubrication device comprising a solid lubricant disposed between and in contact with a first electrode and a second electrode dimensioned and arranged such that application of an electric potential between the first electrode and the second electrode sufficient to produce an electric arc between the first electrode and the second electrode to produce a plasma in an ambient atmosphere at an ambient pressure which vaporizes at least a portion of the solid lubricant to produce a vapor stream comprising the solid lubricant. Methods to lubricate a surface utilizing the lubrication device in-situ are also disclosed.

Plasma-sprayed coatings for lubrication of a titanium alloy in air at 430 deg C

NASA Technical Reports Server (NTRS)

Sliney, H. E.; Wisander, D. H.

1979-01-01

Plasma sprayed coatings of pure silver and of composite materials containing silver were investigated as possible self lubricating coatings for titanium alloys in air at 430 C. Pure silver provided low friction but was prone to severe plastic deformation and excessive transfer except in coating thicknesses of 0.02 mm or less. Additions of nichrome, calcium fluoride, and glass to silver were all beneficial in reducing plastic deformation and otherwise improving the coatings. The longest coating wear life, low wear of Ti alloy pins in sliding contact with the coatings, and a steady friction coefficient of 0.19 were obtained with a four component coating of 0.17 mm thickness. The coating composition, in weight percent is 30 nichrome-30 Ag-25 CaF2-15 glass.

Synthesis of new high performance lubricants and solid lubricants

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

Lagow, Richard J.

1993-04-08

In our second year of funding we began the testing phase of a number of new classes of lubricants. Three different testing collaborations have already begun and a fourth one is In the works with Dr. Stephen Hsu of the National Institute of Standards and Technology. Dr. Hsu also plans to test some of the same materials for us that Shell Development is studying. With Dr. Bill Jones of NASA, we are studying the effects of branching an high temperature lubricant properties in perfluoropolyethers, Initially Bill Jones is comparing the lubrication and physical properties of perfluorotetraglyme and the following twomore » spherical perfluoropolyethers, Note that one contains a fluorocarbon chain and the other one contains a fluorocarbon ether chain. The synthesis of these was reported in the last progress report. With Professor Patricia Thiel of Iowa State University, we are working on studies of perfluoromethylene oxide ethers and have prepared a series of four of these polyethers to study in collaboration with her research group. These perfluoromethylene oxide ethers have the best low temperature properties of any known lubricants. Thiel's group is studying their interactions with metals under extreme conditions. Thirdly, we have also begun an Interaction with W. August Birke of Shell Development Company in Houston for whom we have already prepared samples of the chlorine-substituted fluorocarbon polyether lubricants whose structures appear on page 54 of our research proposal. Each of these four structures is thought to have potential as lubricant additives to motor oils. We also have underway syntheses of other fluorine-containing branched ether lubricants. These new materials which are also promising as antifriction additives for motor oils appear ahead of the perfluoro additives as Appendix I to the progress report. Additionally for Birke and Shell Development we have at their request prepared the novel compound perfluoro salicylic acid. This synthesis was

Effects of coating materials on nanoindentation hardness of enamel and adjacent areas.

PubMed

Alsayed, Ehab Z; Hariri, Ilnaz; Nakashima, Syozi; Shimada, Yasushi; Bakhsh, Turki A; Tagami, Junji; Sadr, Alireza

2016-06-01

Materials that can be applied as thin coatings and actively release fluoride or other bioavailable ions for reinforcing dental hard tissue deserve further investigation. In this study we assessed the potential of resin coating materials in protection of underlying and adjacent enamel against demineralization challenge using nanoindentation. Enamel was coated using Giomer (PRG Barrier Coat, PBC), resin-modified glass-ionomer (Clinpro XT Varnish, CXT), two-step self-etch adhesive (Clearfil SE Protect, SEP) or no coating (control). After 5000 thermal cycles and one-week demineralization challenge, Martens hardness of enamel beneath the coating, uncoated area and intermediate areas was measured using a Berkovich tip under 2mN load up to 200μm depth. Integrated hardness and 10-μm surface zone hardness were compared among groups. Nanoindentation and scanning electron microscopy suggested that all materials effectively prevented demineralization in coated area. Uncoated areas presented different hardness trends; PBC showed a remarkable peak at the surface zone before reaching as low as the control, while CXT showed relatively high hardness values at all depths. Ion-release from coating materials affects different layers of enamel. Coatings with fluoride-releasing glass fillers contributed to reinforcement of adjacent enamel. Surface prereacted glass filler-containing PBC superficially protected neighboring enamel against demineralization, while resin-modified glass-ionomer with calcium (CXT) improved in-depth protection. Cross-sectional hardness mapping of enamel on a wide range of locations revealed minute differences in its structure. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Microstructures and Properties of Plasma Sprayed Ni Based Coatings Reinforced by TiN/C1-xNxTi Generated from In-Situ Solid-Gas Reaction.

PubMed

Wang, Wenquan; Li, Wenmo; Xu, Hongyong

2017-07-11

The strengthening hard phases TiN/C 1- x N x Ti were generated by in-situ solid-gas reaction in Ni-based composite coatings prepared using a plasma spray welding process to reinforce the wear resistance of the coatings. The microstructures and properties of the coatings were investigated. The results showed that the coatings mainly consisted of phases such as TiN, C 1- x N x Ti, TiC, etc. A small amount of CrB, M₇C₃, and M 23 C₆ were also detected in the coatings by micro-analysis method. Compared with the originally pure NiCrBSi coatings, the hardness of the NiCrBSi coatings reinforced by in-situ solid-gas reaction was 900 HV 0.5 , increased by more than 35%. Consequently, the wear resistance of the reinforced coatings was greatly improved due to the finely and uniformly dispersed hard phases mentioned above. The weight losses after wear test for the two kinds of coatings were 15 mg and 8 mg, respectively.

The Effect of Hard Coated Metals on the Thermo-Oxidative Stability of a Branched Perfluoropolyalklyether Lubricant (Preprint)

DTIC Science & Technology

2006-10-01

metallurgy techniques for stainless steels and other type materials is of the utmost importance to improve the stability of PFPAE lubricants in high...minimized such as with stainless steels . Stainless steels have a high percentage of chromium (>10%) on the surface that produces a protective oxide...of this effort is twofold: 1) to determine the resistance of a 4 carburized stainless steel to the attack of a PFPAE lubricant using M-50 steel as a

Effect of bond coat and preheat on the microstructure, hardness, and porosity of flame sprayed tungsten carbide coatings

NASA Astrophysics Data System (ADS)

Winarto, Winarto; Sofyan, Nofrijon; Rooscote, Didi

2017-06-01

Thermally sprayed coatings are used to improve the surface properties of tool steel materials. Bond coatings are commonly used as intermediate layers deposited on steel substrates (i.e. H13 tool steel) before the top coat is applied in order to enhance a number of critical performance criteria including adhesion of a barrier coating, limiting atomic migration of the base metal, and corrosion resistance. This paper presents the experimental results regarding the effect of nickel bond coat and preheats temperatures (i.e. 200°C, 300°C and 400°C) on microstructure, hardness, and porosity of tungsten carbide coatings sprayed by flame thermal coating. Micro-hardness, porosity and microstructure of tungsten carbide coatings are evaluated by using micro-hardness testing, optical microscopy, scanning electron microscopy, and X-ray diffraction. The results show that nickel bond coatings reduce the susceptibility of micro crack formation at the bonding area interfaces. The percentage of porosity level on the tungsten carbide coatings with nickel bond coat decreases from 5.36 % to 2.78% with the increase of preheat temperature of the steel substrate of H13 from 200°C to 400°C. The optimum hardness of tungsten carbide coatings is 1717 HVN in average resulted from the preheat temperature of 300°C.

Fabrics coated with lubricated nanostructures display robust omniphobicity

DOE PAGES

Shillingford, Cicely; MacCallum, Noah; Wong, Tak -Sing; ...

2013-12-11

The development of a stain-resistant and pressure-stable textile is desirable for consumer and industrial applications alike, yet it remains a challenge that current technologies have been unable to fully address. Traditional superhydrophobic surfaces, inspired by the lotus plant, are characterized by two main components: hydrophobic chemical functionalization and surface roughness. While this approach produces water-resistant surfaces, these materials have critical weaknesses that hinder their practical utility, in particular as robust stain-free fabrics. For example, traditional superhydrophobic surfaces fail (i.e., become stained) when exposed to low-surface-tension liquids, under pressure when impacted by a high-velocity stream of water (e.g., rain), and whenmore » exposed to physical forces such as abrasion and twisting. We have recently introduced slippery lubricant-infused porous surfaces (SLIPS), a self-healing, pressure-tolerant and omniphobic surface, to address these issues. However we present the rational design and optimization of nanostructured lubricant-infused fabrics and demonstrate markedly improved performance over traditional superhydrophobic textile treatments: SLIPS-functionalized cotton and polyester fabrics exhibit decreased contact angle hysteresis and sliding angles, omni-repellent properties against various fluids including polar and nonpolar liquids, pressure tolerance and mechanical robustness, all of which are not readily achievable with the state-of-the-art superhydrophobic coatings.« less

Fabrics coated with lubricated nanostructures display robust omniphobicity

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

Shillingford, C; MacCallum, N; Wong, TS

2013-12-11

The development of a stain-resistant and pressure-stable textile is desirable for consumer and industrial applications alike, yet it remains a challenge that current technologies have been unable to fully address. Traditional superhydrophobic surfaces, inspired by the lotus plant, are characterized by two main components: hydrophobic chemical functionalization and surface roughness. While this approach produces water-resistant surfaces, these materials have critical weaknesses that hinder their practical utility, in particular as robust stain-free fabrics. For example, traditional superhydrophobic surfaces fail (i.e., become stained) when exposed to low-surface-tension liquids, under pressure when impacted by a high-velocity stream of water (e. g., rain), andmore » when exposed to physical forces such as abrasion and twisting. We have recently introduced slippery lubricant-infused porous surfaces (SLIPS), a self-healing, pressure-tolerant and omniphobic surface, to address these issues. Herein we present the rational design and optimization of nanostructured lubricant-infused fabrics and demonstrate markedly improved performance over traditional superhydrophobic textile treatments: SLIPS-functionalized cotton and polyester fabrics exhibit decreased contact angle hysteresis and sliding angles, omni-repellent properties against various fluids including polar and nonpolar liquids, pressure tolerance and mechanical robustness, all of which are not readily achievable with the state-of-the-art superhydrophobic coatings.« less

Fabrics coated with lubricated nanostructures display robust omniphobicity.

PubMed

Shillingford, Cicely; MacCallum, Noah; Wong, Tak-Sing; Kim, Philseok; Aizenberg, Joanna

2014-01-10

The development of a stain-resistant and pressure-stable textile is desirable for consumer and industrial applications alike, yet it remains a challenge that current technologies have been unable to fully address. Traditional superhydrophobic surfaces, inspired by the lotus plant, are characterized by two main components: hydrophobic chemical functionalization and surface roughness. While this approach produces water-resistant surfaces, these materials have critical weaknesses that hinder their practical utility, in particular as robust stain-free fabrics. For example, traditional superhydrophobic surfaces fail (i.e., become stained) when exposed to low-surface-tension liquids, under pressure when impacted by a high-velocity stream of water (e.g., rain), and when exposed to physical forces such as abrasion and twisting. We have recently introduced slippery lubricant-infused porous surfaces (SLIPS), a self-healing, pressure-tolerant and omniphobic surface, to address these issues. Herein we present the rational design and optimization of nanostructured lubricant-infused fabrics and demonstrate markedly improved performance over traditional superhydrophobic textile treatments: SLIPS-functionalized cotton and polyester fabrics exhibit decreased contact angle hysteresis and sliding angles, omni-repellent properties against various fluids including polar and nonpolar liquids, pressure tolerance and mechanical robustness, all of which are not readily achievable with the state-of-the-art superhydrophobic coatings.

Fabrics coated with lubricated nanostructures display robust omniphobicity

NASA Astrophysics Data System (ADS)

Shillingford, Cicely; MacCallum, Noah; Wong, Tak-Sing; Kim, Philseok; Aizenberg, Joanna

2014-01-01

The development of a stain-resistant and pressure-stable textile is desirable for consumer and industrial applications alike, yet it remains a challenge that current technologies have been unable to fully address. Traditional superhydrophobic surfaces, inspired by the lotus plant, are characterized by two main components: hydrophobic chemical functionalization and surface roughness. While this approach produces water-resistant surfaces, these materials have critical weaknesses that hinder their practical utility, in particular as robust stain-free fabrics. For example, traditional superhydrophobic surfaces fail (i.e., become stained) when exposed to low-surface-tension liquids, under pressure when impacted by a high-velocity stream of water (e.g., rain), and when exposed to physical forces such as abrasion and twisting. We have recently introduced slippery lubricant-infused porous surfaces (SLIPS), a self-healing, pressure-tolerant and omniphobic surface, to address these issues. Herein we present the rational design and optimization of nanostructured lubricant-infused fabrics and demonstrate markedly improved performance over traditional superhydrophobic textile treatments: SLIPS-functionalized cotton and polyester fabrics exhibit decreased contact angle hysteresis and sliding angles, omni-repellent properties against various fluids including polar and nonpolar liquids, pressure tolerance and mechanical robustness, all of which are not readily achievable with the state-of-the-art superhydrophobic coatings.

Heat Treatment Used to Strengthen Enabling Coating Technology for Oil-Free Turbomachinery

NASA Technical Reports Server (NTRS)

Edmonds, Brian J.; DellaCorte, Christopher

2002-01-01

The PS304 high-temperature solid lubricant coating is a key enabling technology for Oil- Free turbomachinery propulsion and power systems. Breakthroughs in the performance of advanced foil air bearings and improvements in computer-based finite element modeling techniques are the key technologies enabling the development of Oil-Free aircraft engines being pursued by the Oil-Free Turbomachinery team at the NASA Glenn Research Center. PS304 is a plasma spray coating applied to the surface of shafts operating against foil air bearings or in any other component requiring solid lubrication at high temperatures, where conventional materials such as graphite cannot function.

Lubricant-infused nanoparticulate coatings assembled by layer-by-layer deposition

DOE PAGES

Sunny, Steffi; Vogel, Nicolas; Howell, Caitlin; ...

2014-09-01

Omniphobic coatings are designed to repel a wide range of liquids without leaving stains on the surface. A practical coating should exhibit stable repellency, show no interference with color or transparency of the underlying substrate and, ideally, be deposited in a simple process on arbitrarily shaped surfaces. We use layer-by-layer (LbL) deposition of negatively charged silica nanoparticles and positively charged polyelectrolytes to create nanoscale surface structures that are further surface-functionalized with fluorinated silanes and infiltrated with fluorinated oil, forming a smooth, highly repellent coating on surfaces of different materials and shapes. We show that four or more LbL cycles introducemore » sufficient surface roughness to effectively immobilize the lubricant into the nanoporous coating and provide a stable liquid interface that repels water, low-surface-tension liquids and complex fluids. The absence of hierarchical structures and the small size of the silica nanoparticles enables complete transparency of the coating, with light transmittance exceeding that of normal glass. The coating is mechanically robust, maintains its repellency after exposure to continuous flow for several days and prevents adsorption of streptavidin as a model protein. As a result, the LbL process is conceptually simple, of low cost, environmentally benign, scalable, automatable and therefore may present an efficient synthetic route to non-fouling materials.« less

Lubricant-Infused Nanoparticulate Coatings Assembled by Layer-by-Layer Deposition

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

Sunny, S; Vogel, N; Howell, C

2014-09-01

Omniphobic coatings are designed to repel a wide range of liquids without leaving stains on the surface. A practical coating should exhibit stable repellency, show no interference with color or transparency of the underlying substrate and, ideally, be deposited in a simple process on arbitrarily shaped surfaces. We use layer-by-layer (LbL) deposition of negatively charged silica nanoparticles and positively charged polyelectrolytes to create nanoscale surface structures that are further surface-functionalized with fluorinated silanes and infiltrated with fluorinated oil, forming a smooth, highly repellent coating on surfaces of different materials and shapes. We show that four or more LbL cycles introducemore » sufficient surface roughness to effectively immobilize the lubricant into the nanoporous coating and provide a stable liquid interface that repels water, low-surface-tension liquids and complex fluids. The absence of hierarchical structures and the small size of the silica nanoparticles enables complete transparency of the coating, with light transmittance exceeding that of normal glass. The coating is mechanically robust, maintains its repellency after exposure to continuous flow for several days and prevents adsorption of streptavidin as a model protein. The LbL process is conceptually simple, of low cost, environmentally benign, scalable, automatable and therefore may present an efficient synthetic route to non-fouling materials.« less

Effect of 2D WS2 Addition on Cold-Sprayed Aluminum Coating

NASA Astrophysics Data System (ADS)

Loganathan, Archana; Rengifo, Sara; Hernandez, Alexander Franco; Emirov, Yusuf; Zhang, Cheng; Boesl, Benjamin; Karthikeyan, Jeganathan; Agarwal, Arvind

2017-10-01

Tungsten disulfide (WS2) has excellent solid lubrication properties due to its 2D layered structure. This study focuses on depositing Al-2 wt.% WS2 composite coating by cold spray technique. The effect of WS2 addition on the microstructure, mechanical and tribological properties of the composite coatings is examined in the as-deposited and heat-treated conditions. After heat treatment, the coating density increased to 99% with improved intersplat bonding. The microhardness of the heat-treated Al-2 wt.% WS2 coating increased by 56% as compared to the as-sprayed coating. The wear resistance of heat-treated Al-2 wt.% WS2 coating improved by 75% with a synergistic reduction in the coefficient of friction (COF) by 51%. Transmission electron microscopy investigation reveals the presence of layered WS2 within aluminum splats with a strong interface. This study shows that cold spraying can be effectively used to integrate 2D layered WS2 as a solid lubricant in the metallic coatings.

Tribological properties and lubrication mechanism of in situ graphene-nickel matrix composite impregnated with lubricating oil

NASA Astrophysics Data System (ADS)

Lei, Yu; Du, Jinfang; Pang, Xianjuan; Wang, Haizhong; Yang, Hua; Jiang, Jinlong

2018-05-01

A solid-liquid synergetic lubricating system has been designed to develop a novel self-lubricating nickel matrix composite. The graphene-nickel (G-Ni) matrix composite with porous structure was fabricated by in situ growing graphene in bulk nickel using a powder metallurgy method. The porous structures of the composite were used to store polyalphaolefin (PAO) oil for self-lubricating. It is found that the G-Ni matrix composite under oil lubrication condition exhibited superior tribological properties as compared to pure nickel and the composite under dry sliding condition. The prestored oil was released from pores to the sliding surface forming a lubricating oil film during friction process. This lubricating oil film can protect the worn surface from severe oxidation, and help the formation and transfer of a carbon-based solid tribofilm derived from graphene and lubricating oil. This solid (graphene)-liquid (oil) synergistic lubricating mechanism is responsible for the reduction of friction coefficient and improvement of wear resistance of the in situ fabricated G-Ni matrix composite.

MoS2 solid-lubricating film fabricated by atomic layer deposition on Si substrate

NASA Astrophysics Data System (ADS)

Huang, Yazhou; Liu, Lei; Lv, Jun; Yang, Junjie; Sha, Jingjie; Chen, Yunfei

2018-04-01

How to reduce friction for improving efficiency in the usage of energy is a constant challenge. Layered material like MoS2 has long been recognized as an effective surface lubricant. Due to low interfacial shear strengths, MoS2 is endowed with nominal frictional coefficient. In this work, MoS2 solid-lubricating film was directly grown by atomic layer deposition (ALD) on Si substrate using MoCl5 and H2S. Various methods were used to observe the grown MoS2 film. Moreover, nanotribological properties of the film were observed by an atomic force microscope (AFM). Results show that MoS2 film can effectively reduce the friction force by about 30-45% under different loads, indicating the huge application value of the film as a solid lubricant. Besides the interlayer-interfaces-sliding, the smaller capillary is another reason why the grown MoS2 film has smaller friction force than that of Si.

Robust and Drain Resistant Lubricated Omniphobic Fabrics

NASA Astrophysics Data System (ADS)

Kido, Cassidee; Damle, Viraj; Sun, Xiaoda; Roopesh, Ajay; Doudrick, Kyle; Rykaczewski, Konrad

2014-11-01

The implications of omniphobic fabrics range from stainproof clothing to civilian and military protection from chemical weapons. The challenge comes in developing a product that remains effective in repelling droplets of liquids with a wide range of surface tensions even after being subjected to various stimuli imposed by human use. Omniphobic fabrics can be made by infusing hydrophobic nanoparticle coated fibers with a low surface energy lubricant. These types of lubricant impregnated surfaces can shed large deposited droplets as well as condensed microdroplets of variety of low surface tension liquids. However, here we show that lubricated omniphobic fabrics can easily lose their properties due to degradation of the nanostructure coating or drainage of the lubricant upon contact with a porous surface. We also demonstrate that this issue can be resolved with use of cross-linked polymer coated fibers that are swollen with the lubricant. Use of flexible polymers avoids structure degradation due to fabric deformation, while swelling of the polymer with lubricant minimizes lubricant drainage upon contact maintaining the omniphobic characteristics of the fabric. KR acknowledges startup funding from ASU and collaborative effort with Dr. Tim Burgin and James R. Lee from Naval Surface Warfare Center Dahlgren Division.

Tribological study of novel metal-doped carbon-based coatings with enhanced thermal stability

NASA Astrophysics Data System (ADS)

Mandal, Paranjayee

Low friction and high temperature wear resistant PVD coatings are in high demand for use on engine components, which operate in extreme environment. Diamond-like-carbon (DLC) coatings are extensively used for this purpose due to their excellent tribological properties. However, DLC degrades at high temperature and pressure conditions leading to significant increase in friction and wear rate even in the presence of lubricant. To withstand high working temperature and simultaneously maintain improved tribological properties in lubricated condition at ambient and at high temperature, both the transitional metals Mo and W are simultaneously introduced in a carbon-based coating (Mo-W-C) for the first time utilising the benefits of smart material combination and High Power Impulse Magnetron Sputtering (HIPIMS).This research includes development of Mo-W-C coating and investigation of thermal stability and tribological properties at ambient and high temperatures. The as-deposited Mo-W-C coating contains nanocrystalline almost X-ray amorphous structure and show dense microstructure, good adhesion with substrate (Lc -80 N) and high hardness (-17 GPa). During boundary lubricated sliding (commercially available engine oil without friction modifier used as lubricant) at ambient temperature, Mo-W-C coating outperforms commercially available state-of-the-art DLC coatings by providing significantly low friction (u- 0.03 - 0.05) and excellent wear resistance (no measurable wear). When lubricated sliding tests are carried out at 200°C, Mo-W-C coating provides low friction similar to ambient temperature, whereas degradation of DLC coating properties fails to maintain low friction coefficient.A range of surface analyses techniques reveal "in-situ" formation of solid lubricants (WS2 and M0S2) at the tribo-contacts due to tribochemically reactive wear mechanism at ambient and high temperature. Mo-W-C coating reacts with EP additives present in the engine oil during sliding to form WS2

Laser ablated hard coating for microtools

DOEpatents

McLean, II, William; Balooch, Mehdi; Siekhaus, Wigbert J.

1998-05-05

Wear-resistant coatings composed of laser ablated hard carbon films, are deposited by pulsed laser ablation using visible light, on instruments such as microscope tips and micro-surgical tools. Hard carbon, known as diamond-like carbon (DLC), films produced by pulsed laser ablation using visible light enhances the abrasion resistance, wear characteristics, and lifetimes of small tools or instruments, such as small, sharp silicon tips used in atomic probe microscopy without significantly affecting the sharpness or size of these devices. For example, a 10-20 nm layer of diamond-like carbon on a standard silicon atomic force microscope (AFM) tip, enables the useful operating life of the tip to be increased by at least twofold. Moreover, the low inherent friction coefficient of the DLC coating leads to higher resolution for AFM tips operating in the contact mode.

Laser ablated hard coating for microtools

DOEpatents

McLean, W. II; Balooch, M.; Siekhaus, W.J.

1998-05-05

Wear-resistant coatings composed of laser ablated hard carbon films, are deposited by pulsed laser ablation using visible light, on instruments such as microscope tips and micro-surgical tools. Hard carbon, known as diamond-like carbon (DLC), films produced by pulsed laser ablation using visible light enhances the abrasion resistance, wear characteristics, and lifetimes of small tools or instruments, such as small, sharp silicon tips used in atomic probe microscopy without significantly affecting the sharpness or size of these devices. For example, a 10--20 nm layer of diamond-like carbon on a standard silicon atomic force microscope (AFM) tip, enables the useful operating life of the tip to be increased by at least twofold. Moreover, the low inherent friction coefficient of the DLC coating leads to higher resolution for AFM tips operating in the contact mode. 12 figs.

NASA PS304 Lubricant Tested in World's First Commercial Oil-Free Gas Turbine

NASA Technical Reports Server (NTRS)

Weaver, Harold F.

2003-01-01

In a marriage of research and commercial technology, a 30-kW Oil-Free Capstone microturbine electrical generator unit has been installed and is serving as a test bed for long-term life-cycle testing of NASA-developed PS304 shaft coatings. The coatings are used to reduce friction and wear of the turbine engine s foil air bearings during startup and shut down when sliding occurs, prior to the formation of a lubricating air film. This testing supports NASA Glenn Research Center s effort to develop Oil-Free gas turbine aircraft propulsion systems, which will employ advanced foil air bearings and NASA s PS304 high temperature solid lubricant to replace the ball bearings and lubricating oil found in conventional engines. Glenn s Oil-Free Turbomachinery team s current project is the demonstration of an Oil-Free business jet engine. In anticipation of future flight certification of Oil-Free aircraft engines, long-term endurance and durability tests are being conducted in a relevant gas turbine environment using the Capstone microturbine engine. By operating the engine now, valuable performance data for PS304 shaft coatings and for industry s foil air bearings are being accumulated.

A three-dimensional model for lubricant depletion under sliding condition on bit patterned media of hard disk drives

NASA Astrophysics Data System (ADS)

Wu, Lin

2018-05-01

In this paper, we model the depletion dynamics of the molecularly thin layer of lubricants on a bit patterned media disk of hard disk drives under a sliding air bearing head. The dominant physics and consequently, the lubricant depletion dynamics on a patterned disk are shown to be significantly different from the well-studied cases of a smooth disk. Our results indicate that the surface tension effect, which is negligible on a flat disk, apparently suppresses depletion by enforcing a bottleneck effect around the disk pattern peak regions to thwart the migration of lubricants. When the disjoining pressure is relatively small, it assists the depletion. But, when the disjoining pressure becomes dominant, the disjoining pressure resists depletion. Disk pattern orientation plays a critical role in the depletion process. The effect of disk pattern orientation on depletion originates from its complex interaction with other intermingled factors of external air shearing stress distribution and lubricant particle trajectory. Patterning a disk surface with nanostructures of high density, large height/pitch ratio, and particular orientation is demonstrated to be one efficient way to alleviate the formation of lubricant depletion tracks.

Development of surface coatings for air-lubricated, compliant journal bearings to 650 C

NASA Technical Reports Server (NTRS)

Bhushan, B.; Gray, S.

1978-01-01

Surface coatings for an air-lubricated, compliant journal for an automotive gas turbine engine were tested to find those capable of withstanding temperatures of either 540 C (1000 F) or 650 C (1200 F). Also, the coatings have to be capable of surviving the start-stop sliding contact cycles prior to rotor lift-off and at touchdown. Selected coating combinations were tested in start-stop tests at 14 kPa (2 psi) loading for 2000 cycles at room and maximum temperatures. Specific coating recommendations are: Cdo and graphite on foil versus chrome carbide on journal up to 370 C (700 F); NASA PS-120 (Tribaloy 400, silver, and CaF2) on journal versus uncoated foil up to 540 C (1000 F); and chemically adherent Cr2O3 on journal and foil up to 650 C (1200 F). The chemically adherent Cr2O3 coating system was further tested successfully at 35 kPa (5 psi) loading for 2000 start-stop cycles.

Solid-Lubricant, Polymer - Polymeric and Functionalized Fiber- and Powder Reinforced Composites of Ultra-High Molecular Weight Polyethylene

NASA Astrophysics Data System (ADS)

Panin, S. V.; Alexenko, V. O.; Buslovich, D. G.; Anh, Nguyen Duc; Qitao, Huang

2018-01-01

Mechanical and tribotechnical characteristics of solid-lubricant and polymer-polymeric composites of UHMWPE were studied for the sake of design extrudable, wear-resistant, self-lubricant polymer mixtures for Additive Manufacturing (AM). Tribotechnical properties of UHMWPE blends with the optimized content of solid lubricant fillers (polytetrafluoroethylene, calcium stearate, molybdenum disulphide, colloidal graphite, boron nitride) were studied under dry sliding friction at different velocities (V = 0.3 and 0.5 m/s) and loads (P = 60 and 140 N). Also, in order to increase strength and wear-resistance of UHMWPE composites they were reinforced with wollastonite microfibers and aluminum metahydroxide AlO (OH) microparticles preliminary treated (functionalized) in polyorganosiloxane. The comparison on measured mechanical and tribotechnical properties are given with interpretation of the mechanisms of observed phenomenon.

Analysis of hazardous organic residues from sodium hydrosulfite industry and utilization as raw materials in a novel solid lubricant production.

PubMed

Shang, Jiwu; Zhang, Yihe; Zhou, Fengshan; Lv, Fengzhu; Han, Feng; Lu, Jinbo; Meng, Xianghai; Chu, Paul K; Ye, Zhengfang; Xing, Jing

2011-12-30

The hazardous organic residual wastes produced by the sodium hydrosulfite industry are demonstrated to be convertible into a novel solid lubricant. Identification and isolation of the organic residues are achieved by Fourier transform infrared (FTIR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR). FTIR and GC-MS provide important information about the residues and the two main components obtained by column chromatography are further analyzed by NMR. The main organic residues are found to be thiodiglycol and 2,2'-dithiodiethanol which have potential applications in petroleum drilling because of their S-S and/or C-S functional groups. The lubricity of the organic residues is subsequently studied and the influence of different adsorbents on the lubricity is investigated and discussed. This homemade lubricant is observed to have good lubricity and by increasing the concentration of the commercial solid lubricant M, the lubricity diminishes. The process is expected to not only have commercial impact but also help to reduce environmental pollution. Copyright © 2011 Elsevier B.V. All rights reserved.

Dry coating, a novel coating technology for solid pharmaceutical dosage forms.

PubMed

Luo, Yanfeng; Zhu, Jesse; Ma, Yingliang; Zhang, Hui

2008-06-24

Dry coating is a coating technology for solid pharmaceutical dosage forms derived from powder coating of metals. In this technology, powdered coating materials are directly coated onto solid dosage forms without using any solvent, and then heated and cured to form a coat. As a result, this technology can overcome such disadvantages caused by solvents in conventional liquid coating as serious air pollution, high time- and energy-consumption and expensive operation cost encountered by liquid coating. Several dry coating technologies, including plasticizer-dry-coating, electrostatic-dry-coating, heat-dry-coating and plasticizer-electrostatic-heat-dry-coating have been developed and extensively reported. This mini-review summarized the fundamental principles and coating processes of various dry coating technologies, and thoroughly analyzed their advantages and disadvantages as well as commercialization potentials.

Tribological evaluation of PS300: A new chrome oxide based solid lubricant coating sliding against Al2O3 From 25 to 650 C

NASA Technical Reports Server (NTRS)

DellaCorte, C.; Laskowski, J. A.

1996-01-01

This paper presents the tribological characteristics of Al203 sliding against PS300; a chrome oxide based self lubricating coating. Al203 pins were slid against PS300 coated superalloy disks in air, under a 4.9 N load at velocities of 1 to 8 m/s. At a sliding velocity of 1 m/s, friction ranged from 0.6 at 25 C to 0.2 at 650 C. Wear factors for the Al203 pins were in the 10(exp -7) mm(exp 3)/N-m range and for the PS300 coating was in the 10(exp -5) mm(exp 3)/N-m range. The test results suggest that increased surface temperature resulting from either frictional heating, generated by increased sliding velocity, or ambient heating caused a reduction in friction and wear of the sliding couple. Based upon these results, the tested material combination is a promising candidate for high temperature wear applications.

Lubricant Rheology in Concentrated Contacts

NASA Technical Reports Server (NTRS)

Jacobson, B. O.

1984-01-01

Lubricant behavior in highly stressed situtations shows that a Newtonian model for lubricant rheology is insufficient for explanation of traction behavior. The oil film build up is predicted by using a Newtonian lubricant model except at high slide to roll ratios and at very high loads, where the nonNewtonian behavior starts to be important already outside the Hertzian contact area. Static and dynamic experiments are reported. In static experiments the pressure is applied to the lubricant more than a million times longer than in an EHD contact. Depending on the pressure-temperature history of the experiment the lubricant will become a crystallized or amorphous solid at high pressures. In dynamic experiments, the oil is in an amorphous solid state. Depending on the viscosity, time scale, elasticity of the oil and the bearing surfaces, the oil film pressure, shear strain rate and the type of lubricant, different properties of the oil are important for prediction of shear stresses in the oil. The different proposed models for the lubricant, which describe it to a Newtonian liquid, an elastic liquid, a plastic liquid and an elastic-plastic solid.

Friction and wear behaviour of Mo-W doped carbon-based coating during boundary lubricated sliding

NASA Astrophysics Data System (ADS)

Hovsepian, Papken Eh.; Mandal, Paranjayee; Ehiasarian, Arutiun P.; Sáfrán, G.; Tietema, R.; Doerwald, D.

2016-03-01

A molybdenum and tungsten doped carbon-based coating (Mo-W-C) was developed in order to provide low friction in boundary lubricated sliding condition at ambient and at high temperature. The Mo-W-C coating showed the lowest friction coefficient among a number of commercially available state-of-the-art DLC coatings at ambient temperature. At elevated temperature (200 °C), Mo-W-C coating showed a significant reduction in friction coefficient with sliding distance in contrast to DLC coatings. Raman spectroscopy revealed the importance of combined Mo and W doping for achieving low friction at both ambient and high temperature. The significant decrease in friction and wear rate was attributed to the presence of graphitic carbon debris (from coating) and 'in situ' formed metal sulphides (WS2 and MoS2, where metals were supplied from coating and sulphur from engine oil) in the transfer layer.

Investigation on MoS2 and graphite coatings and their effects on the tribological properties of the radial spherical plain bearings

NASA Astrophysics Data System (ADS)

Qiu, Ming; Lu, Jianjun; Li, Yingchun; Lv, Guisen

2016-07-01

With constant enlargement of the application areas of the spherical plain bearings, higher quality lubrication of the bearings is required. To solve the lubricating problems of spherical plain bearings under high temperature, high vacuum, high speed, heavy loads and strong oxidation conditions, it is urgent for us to develop more excellent self-lubricating technologies. In this paper, the bonded solid lubricant coatings, which use inorganic phosphate as the binder, the mixture of MoS2 and graphite with two different weight proportions as the solid lubricant, are prepared by spraying under three different spray gun pressures. The bonding strength tests on the coatings show that the best spraying pressure is 0.2 MPa and the better mixing proportion of MoS2 to Graphite is 3:1. Then for the radial spherical plain bearings with steel/steel friction pair, after the coatings are made on the inner ring outer surfaces, the friction coefficient, the wear loss and the friction temperature of the bearings under four oscillating frequencies are investigated by a self-made tribo-tester. The test results, SEM of the worn morphologies and EDS of worn areas show that tribological properties of the bearing are obviously improved by the bonded solid lubricant coatings. When sprayed under the spray gun pressure of 0.2 MPa, the bearings have better anti-friction and anti-wear properties than those sprayed under 0.1 MPa and 0.3 MPa. Further as proved from the XPS analysis, between the coating with 3:1 mixing ratio of MoS2 to Graphite and the coating with 1:1 ratio, the former has less oxidation occurred on the surface and therefore has better tribological characteristics than the latter. This paper provides a reference to developing a new product of the radial spherical plain bearings with high bonding strength, oxidation resistance and abrasion resistance.

Solid Lubrication by Multiwalled Carbon Nanotubes in Air and in Vacuum for Space and Aeronautics Applications

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa; Street, Kenneth W., Jr.; Andraws, Rodney; Jacques, David; VanderWal, Randy L.; Sayir, Ali

2005-01-01

To evaluate recently developed aligned multiwalled carbon nanotubes (MWNTs) and dispersed MWNTs for solid lubrication applications, unidirectional sliding friction experiments were conducted with 440 C stainless steel balls and hemispherical alumina-yttria stabilized zirconia pins in sliding contact with the MWNTs deposited on quartz disks in air and in vacuum. The results indicate that MWNTs have superior solid lubrication friction properties and endurance lives in air and vacuum under dry conditions. The coefficient of friction of the dispersed MWNTs is close to 0.05 and 0.009 in air and in vacuum, respectively, showing good dry lubricating ability. The wear life of MWNTs exceeds 1 million passes in both air and vacuum showing good durability. In general, the low coefficient of friction can be attributed to the combination of the transferred, agglomerated patches of MWNTs on the counterpart ball or pin surfaces and the presence of tubular MWNTs at interfaces.

Tribological Performance of PM300 Solid Lubricant Bushings for High Temperature Applications

NASA Technical Reports Server (NTRS)

Striebing, Donald R.; Stanford, Malcolm K.; DellaCorte, Christopher; Rossi, Anne M.

2007-01-01

PM300 is a high temperature solid lubricant material produced through conventional powder metallurgy processing. PM300 is a combination of metal binder (NiCr), hardener (Cr2O3) and lubricant (Ag and BaF2/CaF2) phases and is in commercial use in high temperature furnace conveyors. In this paper, the tribological characteristics of PM300 are evaluated using a newly developed bushing test rig in which PM300 bushings are loaded against rotating steel shafts at temperatures from 25 to 650 C. The data shows that friction and wear are low to moderate and that the lubrication performance (friction) improves with increasing temperature. Several alternative PM300 compositions are evaluated which do not contain silver and are targeted at aircraft gas turbine applications in which environmental compatibility of silver is a concern. It is expected that the data resulting from this research will further the commercialization of this technology.

Tribological Behavior of IN718 Superalloy Coating Fabricated by Laser Additive Manufacturing

NASA Astrophysics Data System (ADS)

Zhang, Yaocheng; Pan, Qiyong; Yang, Li; Li, Ruifeng; Dai, Jun

2017-12-01

The tribological behavior of laser manufactured IN718 superalloy coating are investigated with different applied loads, sliding speeds and lubricating mediums. The wear resistance of laser manufactured IN718 coating is increased by heat treatment due to higher microhardness and homogeneous brittle phase distribution. The principal factors for the wear rate are applied load and lubricating medium. The worn surface of laser manufactured IN718 coating consists of the grooves, crack, wear debris and material delamination generated by the fatigue wear associated with adhesive wear and abrasive wear. The friction coefficients are influenced by the tribological noise decrescence by the tribo-oxidant and the liquid lubricant. The real contact temperature between coating sample and frictional counterpart is higher than the solid-solution temperature of IN718 superalloy, and the effect of surface contact temperature on the orientational microstructure and wear resistance for dry friction and wet friction process is indistinct.

Static evaluation of surface coatings for compliant gas bearings in an oxidizing atmosphere to 650 C

NASA Technical Reports Server (NTRS)

Bhushan, B.; Gray, S.

1978-01-01

Hard wear-resistant coatings and soft low shear strength coatings were developed for an air-lubricated compliant journal bearing for a future automotive gas turbine engine. The coatings were expected to function in either 540 or 650 C ambient. Soft lubricant coatings were generally limited in temperature. Therefore emphasis was on the hard wear-resistant coatings. The coating materials covered were TiC, B4C, Cr3C2, WC, SiC, CrB2, TiB2, Cr2O3, Al2O3, Si3N4, Tribaloy 800, CaF2, CaF2-BaF2 eutectic, Ni-Co, silver, CdO-graphite and proprietary compounds. The coatings on test coupons were subjected to static oven screening tests. The test consisted of exposure of material samples in an oven for 300 h at the maximum temperature (540 or 650 C) and ten temperature cycles from room temperature to the maximum service temperature. On the basis of the specimen examinations the following coatings were recommended for future wear tests: TiC (sputtered), Cr2O3 (sputtered), Si3N4 (sputtered), CdO and graphite (fused), Kaman DES (a proprietary coating), CrB2 (plasma sprayed), Cr3C2 (detonation gun) and NASA PS-106 (plasma sprayed).

Chameleon Coatings: Adaptive Surfaces to Reduce Friction and Wear in Extreme Environments

NASA Astrophysics Data System (ADS)

Muratore, C.; Voevodin, A. A.

2009-08-01

Adaptive nanocomposite coating materials that automatically and reversibly adjust their surface composition and morphology via multiple mechanisms are a promising development for the reduction of friction and wear over broad ranges of ambient conditions encountered in aerospace applications, such as cycling of temperature and atmospheric composition. Materials selection for these composites is based on extensive study of interactions occurring between solid lubricants and their surroundings, especially with novel in situ surface characterization techniques used to identify adaptive behavior on size scales ranging from 10-10 to 10-4 m. Recent insights on operative solid-lubricant mechanisms and their dependency upon the ambient environment are reviewed as a basis for a discussion of the state of the art in solid-lubricant materials.

Effects of Coating Materials and Processing Conditions on Flow Enhancement of Cohesive Acetaminophen Powders by High-Shear Processing With Pharmaceutical Lubricants.

PubMed

Wei, Guoguang; Mangal, Sharad; Denman, John; Gengenbach, Thomas; Lee Bonar, Kevin; Khan, Rubayat I; Qu, Li; Li, Tonglei; Zhou, Qi Tony

2017-10-01

This study has investigated the surface coating efficiency and powder flow improvement of a model cohesive acetaminophen powder by high-shear processing with pharmaceutical lubricants through 2 common equipment, conical comil and high-shear mixer. Effects of coating materials and processing parameters on powder flow and surface coating coverage were evaluated. Both Carr's index and shear cell data indicated that processing with the lubricants using comil or high-shear mixer substantially improved the flow of the cohesive acetaminophen powder. Flow improvement was most pronounced for those processed with 1% wt/wt magnesium stearate, from "cohesive" for the V-blended sample to "easy flowing" for the optimally coated sample. Qualitative and quantitative characterizations demonstrated a greater degree of surface coverage for high-shear mixing compared with comilling; nevertheless, flow properties of the samples at the corresponding optimized conditions were comparable between 2 techniques. Scanning electron microscopy images demonstrated different coating mechanisms with magnesium stearate or l-leucine (magnesium stearate forms a coating layer and leucine coating increases surface roughness). Furthermore, surface coating with hydrophobic magnesium stearate did not retard the dissolution kinetics of acetaminophen. Future studies are warranted to evaluate tableting behavior of such dry-coated pharmaceutical powders. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

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.

Tribological Behavior and Corrosion Resistance of Electroless Ni-B-W Coatings

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Arkadeb; Barman, Tapan Kumar; Sahoo, Prasanta

The present study considers the tribological behavior and corrosion resistance of electroless Ni-B-W coatings deposited on AISI 1040 steel substrates. Coating is characterized using scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction technique. In as-deposited condition, coatings are found to be amorphous. On heat treatment, precipitation of crystalline Ni (1 1 1) and its borides take place. For as-deposited coating, the microhardness is obtained as ˜759HV100 which increases to ˜1181HV100 and ˜1098HV100 when heat treated at 350∘C and 450∘C, respectively. Incorporation of W in Ni-B coating results in an increase of hardness by 89HV100 in as-deposited condition. Heat treatment also results in increase in crystallite size of Ni (1 1 1). Wear rate and coefficient of friction (COF) of the coatings are evaluated on a pin-on-disc setup under both dry and lubricated sliding conditions. Wear resistance is observed to improve on heat treatment with an increase in crystallite size while COF deteriorates. However, in as-deposited condition, wear rate and COF of Ni-B-W coatings improve by ˜5 and ˜3 times, respectively, compared with Ni-B coatings. Wear and friction performance of the coatings are enhanced under lubrication due to the columnar structure of the coatings that retain lubricants. Corrosion resistance of Ni-B-W coating in 3.5% NaCl solution gets improved on heat treatment.

Solid particle erosion mechanisms of protective coatings for aerospace applications

NASA Astrophysics Data System (ADS)

Bousser, Etienne

The main objective of this PhD project is to investigate the material loss mechanisms during Solid Particle Erosion (SPE) of hard protective coatings, including nanocomposite and nanostructured systems. In addition, because of the complex nature of SPE mechanisms, rigorous testing methodologies need to be employed and the effects of all testing parameters need to be fully understood. In this PhD project, the importance of testing methodology is addressed throughout in order to effectively study the SPE mechanisms of brittle materials and coatings. In the initial stage of this thesis, we studied the effect of the addition of silicon (Si) on the microstructure, mechanical properties and, more specifically, on the SPE resistance of thick CrN-based coatings. It was found that the addition of Si significantly improved the erosion resistance and that SPE correlated with the microhardness values, i.e. the coating with the highest microhardness also had the lowest erosion rate (ER). In fact, the ERs showed a much higher dependence on the surface hardness than what has been proposed for brittle erosion mechanisms. In the first article, we study the effects of the particle properties on the SPE behavior of six brittle bulk materials using glass and alumina powders. First, we apply a robust methodology to accurately characterize the elasto-plastic and fracture properties of the studied materials. We then correlate the measured ER to materials' parameters with the help of a morphological study and an analysis of the quasi-static elasto-plastic erosion models. Finally, in order to understand the effects of impact on the particles themselves and to support the energy dissipation-based model proposed here, we study the particle size distributions of the powders before and after erosion testing. It is shown that tests using both powders lead to a material loss mechanism related to lateral fracture, that the higher than predicted velocity exponents point towards a velocity

Surface profiles and modulation of ultra-thin perfluoropolyether lubricant in contact sliding

NASA Astrophysics Data System (ADS)

Sinha, S. K.; Kawaguchi, M.; Kato, T.

2004-08-01

Deformation in shear and associated tribological behaviours of ultra-thin lubricants are of significant importance for the lubrication of magnetic hard disks and for other applications such as micro-electromechanical systems, nano-fluidics and nanotechnology. This paper presents the characteristics of the perfluoropolyether ultra-thin lubricant, in terms of its surface profiles when subjected to a contact sliding test. The results indicate that for a several-monolayers thick (~4.0-4.5 nm) lubricant film, sliding produces a considerable amount of surface roughness due to peaks of lubricant that persist during sliding; however, it can flow back or return to a smooth profile after a lapse of time when the sliding is stopped. For a monolayer-thin (~1.4-1.57 nm) film, the lubricant flow is restricted, and the rough profile created due to sliding persists and almost becomes permanent on the wear track. During sliding, due to high shear stress, a characteristic feature of lubricant profile modulation is observed. This modulation, or waviness, is due to the accumulation of lubricant in piles or islands, giving certain amplitudes and frequencies, which themselves depend upon the percentage of lubricant molecules that are chemically bonded to the substrate and the lubricant thickness. The results indicate that ultra-thin lubricants (monolayer and thicker) behave more like a semi-solid (having some sliding characteristics similar to those of rubbers) than a liquid when subjected to a high shear rate during contact sliding.

Tribology and Microstructure of PS212 with a Cr2O3 Seal Coat

NASA Technical Reports Server (NTRS)

Sliney, Harold E.; Benoy, Patricia A.; Korenyi-Both, Andras; Dellacorte, Christopher

1994-01-01

PS212 is a plasma sprayed metal bonding chrome carbide coating with solid lubricant additives which has lubricating properties at temperatures up to about 900 deg C. The coating is diamond ground to achieve an acceptable tribological surface. But, as with many plasma spray coatings, PS212 is not fully-dense. In this study, a chromium oxide base seal coating is used in an attempt to seal any porosity that is open to the surface of the PS212 coating, and to study the effect of the sealant on the tribological properties of PS212. The results indicate that the seal coating reduces friction and wear when it is applied and then diamond ground leaving a thin layer of seal coating which fills in the surface pits of the PS212 coating.

A continuum theory of a lubrication problem with solid particles

NASA Technical Reports Server (NTRS)

Dai, Fuling; Khonsari, M. M.

1993-01-01

The governing equations for a two-dimensional lubrication problem involving the mixture of a Newtonian fluid with solid particles at an arbitrary volume fraction are developed using the theory of interacting continuua (mixture theory). The equations take the interaction between the fluid and the particles into consideration. Provision is made for the possibility of particle slippage at the boundaries. The equations are simplified assuming that the solid volume fraction varies in the sliding direction alone. Equations are solved for the velocity of the fluid phase and that of the solid phase of the mixture flow in the clearance space of an arbitrary shaped bearing. It is shown that the classical pure fluid case can be recovered as a special case of the solutions presented. Extensive numerical solutions are presented to quantify the effect of particulate solid for a number of pertinent performance parameters for both slider and journal bearings. Included in the results are discussions on the influence of particle slippage on the boundaries as well as the role of the interacting body force between the fluid and solid particles.

Raman microscopic studies of PVD deposited hard ceramic coatings

NASA Astrophysics Data System (ADS)

Constable, Christopher Paul

PVD hard ceramic coatings grown via the combined cathodic arc/unbalance magnetron deposition process were studied using Raman microscopy. Characteristic spectra from binary, multicomponent, multilayered and superlattice coatings were acquired to gain knowledge of the solid-state physics associated with Raman scattering from polycrystalline PVD coatings and to compile a comprehensive spectral database. Defect-induced first order scattering mechanisms were observed which gave rise to two pronounced groups of bands related to the acoustical (150-300cm[-1]) and optical (400-750cm[-1]) parts of the phonon spectrum. Evidence was gathered to support the theory that the optic modes were mainly due to the vibrations of the lighter elements and the acoustic modes due to the vibrations of the heavier elements within the lattice.A study into the deformation and disordering on the Raman spectral bands of PVD coatings was performed. TiAIN and TiZrN coatings were intentionally damaged via scratching methods. These scratches were then analysed by Raman mapping, both across and along, and a detailed spectral interpretation performed. Band broadening occurred which was related to "phonon relaxation mechanisms" as a direct result of the breaking up of coating grains resulting in a larger proportion of grain boundaries per-unit-volume. A direct correlation of the amount of damage with band width was observed. Band shifts were also found to occur which were due to the stresses caused by the scratching process. These shifts were found to be the largest at the edges of scratches. The Raman mapping of "droplets", a defect inherent to PVD deposition processes, found that higher compressive stresses and large amounts of disorder occurred for coating growth onto droplets.Strategies designed to evaluate the ability of Raman microscopy to monitor the extent of real wear on cutting tools were evaluated. The removal of a coating layer and subsequent detection of a base layer proved successful

Friction behavior of 304 stainless steel of varying hardness lubricated with benzene and some benzyl structures

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1974-01-01

The lubricating properties of some benzyl and benzene structures were determined by using 304 stainless steel surfaces strained to various hardness. Friction coefficients and wear track widths were measured with a Bowden-Leben type friction apparatus by using a pin-on-disk specimen configuration. Results obtained indicate that benzyl monosulfide, dibenzyl disulfide, and benzyl alcohol resulted in the lowest friction coefficients for 304 stainless steel, while benzyl ether provided the least surface protection and gave the highest friction. Strainhardening of the 304 stainless steel prior to sliding resulted in reduced friction in dry sliding. With benzyl monosulfide, dibenzyl disulfide, and benzyl alcohol changes in 304 stainless steel hardness had no effect upon friction behavior.

Tribological investigation of diamond-like carbon coated micro-dimpled surface under bovine serum and osteoarthritis oriented synovial fluid

NASA Astrophysics Data System (ADS)

Ghosh, Subir; Choudhury, Dipankar; Roy, Taposh; Mamat, Azuddin Bin; Masjuki, H. H.; Pingguan-Murphy, Belinda

2015-06-01

Osteoarthritis-oriented synovial fluid (OASF), i.e., that typical of a patient with osteoarthritis, has different physical and biological characteristics than bovine serum (BS), a lubricant widely used in biotribological investigations. Micro-dimpled and diamond-like carbon- (DLC) coated surfaces are key emerging interfaces for orthopedic implants. In this study, tribological performances of dimpled surfaces, with and without DLC coating, have been investigated under both BS and OASF. The friction tests were performed utilizing a pin on a disk tribometer, whereas contact pressure, speed, and temperature were simulated to a ‘medium walking gait’ of hip joint conditions. The mechanical properties of the specimen and the physical properties of the lubricant were characterized before the friction test. Raman analysis was conducted to identify the coating condition both before and after the test. The DLC-coated dimpled surface showed maximum hardness and residual stress. A DLC-coated dimpled surface under an OASF lubricated condition yielded a lower friction coefficient and wear compared to those of plain and dimpled specimens. The higher graphitization of coated materials with increasing load was confirmed by Raman spectroscopy.

Lubricating Properties of Ceramic-Bonded Calcium Fluoride Coatings on Nickel-Base Alloys from 75 to 1900 deg F

NASA Technical Reports Server (NTRS)

Sliney, Harold E.

1962-01-01

The endurance life and the friction coefficient of ceramic-bonded calcium fluoride (CaF2) coatings on nickel-base alloys were determined at temperatures from 75 F to 1900 F. The specimen configuration consisted of a hemispherical rider (3/16-in. rad.) sliding against the flat surface of a rotating disk. Increasing the ambient temperature (up to 1500 F) or the sliding velocity generally reduced the friction coefficient and improved coating life. Base-metal selection was critical above 1500 F. For instance, cast Inconel sliding against coated Inconel X was lubricated effectively to 1500 F, but at 1600 F severe blistering of the coatings occurred. However, good lubrication and adherence were obtained for Rene 41 sliding against coated Rene 41 at temperatures up to 1900 F; no blisters developed, coating wear life was fairly good, and the rider wear rate was significantly lower than for the unlubricated metals. Friction coefficients were 0.12 at 1500 F, 0.15 at 1700 F, and 0.17 at 1800 F and 1900 F. Because of its ready availability, Inconel X appears to be the preferred substrate alloy for applications in which the temperature does not exceed 1500 F. Rene 41 would have to be used in applications involving higher temperatures. Improved coating life was derived by either preoxidizing the substrate metals prior to the coating application or by applying a very thin (less than 0.0002 in.) burnished and sintered overlay to the surface of the coating. Preoxidation did not affect the friction coefficient. The overlay generally resulted in a higher friction coefficient than that obtained without the overlay. The combination of both modifications resulted in longer coating life and in friction coefficients intermediate between those obtained with either modification alone.

Hard and low friction nitride coatings and methods for forming the same

DOEpatents

Erdemir, Ali; Urgen, Mustafa; Cakir, Ali Fuat; Eryilmaz, Osman Levent; Kazmanli, Kursat; Keles, Ozgul

2007-05-01

An improved coating material possessing super-hard and low friction properties and a method for forming the same. The improved coating material includes the use of a noble metal or soft metal homogeneously distributed within a hard nitride material. The addition of small amounts of such metals into nitrides such as molybdenum nitride, titanium nitride, and chromium nitride results in as much as increasing of the hardness of the material as well as decreasing the friction coefficient and increasing the oxidation resistance.

Electrodeposition of Nanocrystalline Co-P Coatings as a Hard Chrome Alternative

DTIC Science & Technology

2009-09-02

Electrodeposition  of Nanocrystalline Co‐P  Coatings as a Hard Chrome Alternative Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden...AND SUBTITLE Electrodeposition of Nanocrystalline Co‐P Coatings as a Hard Chrome Alternative 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...Defense Conference – 2 September 2009 Conventional  Electrodeposits Polycrystalline (10‐100 µm) Electrodeposited Nanocrystalline Materials Pulsed

Correlation between hardness and water absorption properties of Saudi kaolin and white clay geopolymer coating

NASA Astrophysics Data System (ADS)

Ramasamy, Shamala; Abdullah, Mohd Mustafa Al Bakri; Huang, Yue; Hussin, Kamarudin; Wang, Jin; Shahedan, Noor Fifinatasha

2017-09-01

Geopolymer is an uprising technology that is being studied worldwide. Geopolymer raw materials are basically aluminosilicate source materials. However, this technology is yet to infiltrate into pipelines and coating industries which initiated our research idea. The idea of creating universal geopolymer based coating material is mainly to help oil and gas industry reduce its maintenance cost. Kaolin based geopolymer paste was coated on glass reinforced epoxy (GRE) substrates which are majorly used as pipeline material in the oil and gas industry at Saudi Arabia. Kaolin and white clay was chosen as raw material to study the possibilities of utilizing underused aluminosilicate raw materials for geopolymer coating. To obtain suitable formulation, Na2SiO3/NaOH ratio was varied from 0.40 untill 0.60 while other parameters such as solid/liquid ratio and NaOH molarity were kept constant at values as per previous works. Geopolymer coated GRE substrates were then subjected to water absorption, flexural strength and hardness test to validate our findings. Water absorption is a crucial test as for coating materials which justifies the pratical usability of the coating product. Upon testing, kaolin and white clay based geopolymer coating each shows promising properties at Na2SiO3/NaOH ratio of 0.45 and 0.50 each.

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.

The Effect of Tic Coated Balls and Stress on the Lubricant Lifetime of a Synthetic Hydrocarbon (pennzane 2001A) Using a Vacuum Spiral Orbit Tribometer

NASA Technical Reports Server (NTRS)

Jansen, Mark J.; Jones, William R., Jr.; Pepper, Stephen V.; Wheeler, Donald R.; Schroeer, Achim; Fluehmann, Freddy; Loewenthal, Stuart H.; Shogrin, Bradley A.

2000-01-01

A vacuum spiral orbit rolling contact tribometer was used to determine effect of varying mean Hertzian stress (1.0, 1.5, 2.0 GPa) and the use of 440C and TiC coated 440C balls on lubricant lifetime of a synthetic hydrocarbon (Pennzane 2001A) on 440C stainless steel. Conditions included 210 rpm, approx. 50 micrograms lubricant, an initial vacuum < 1.3xl0(exp-6) Pa, and room temperature (approx. 23 C). Increasing the mean Hertzian stress resulted in an exponential decrease in lubricant lifetime for both material combinations. Substituting a TiC coated 440C ball showed no increase in lifetime over the 440C ball. The decreasing lifetime with increasing stress level correlated well with energy dissipation calculations.

Intermediate coating layer for high temperature rubbing seals for rotary regenerators

DOEpatents

Schienle, James L.; Strangman, Thomas E.

1995-01-01

A metallic regenerator seal is provided having multi-layer coating comprising a NiCrAlY bond layer, a yttria stabilized zirconia (YSZ) intermediate layer, and a ceramic high temperature solid lubricant surface layer comprising zinc oxide, calcium fluoride, and tin oxide. Because of the YSZ intermediate layer, the coating is thermodynamically stable and resists swelling at high temperatures.

An investigation of material properties and tribological performance of magnetron sputtered thin film coatings

NASA Astrophysics Data System (ADS)

Singh, Harpal

This dissertation is divided into two categories based upon lubrication functionality and its application. The categories are: Dry film lubrication and Fluid film lubrication with thin film coatings. Thin film coatings examined in this work were deposited using closed field unbalanced magnetron sputtering and RF-DC coupled magnetron sputtering systems. In Dry/Solid film lubrication, the mechanical, structural and tribological properties of two Molybdenum disulphide (MoS2) based coatings are examined and evaluated. Among the two coatings, one coating is doped with Ti (Ti-MoS2) and the other is a combination of metal, lubricant and oxide (Sb2O3/Au - MoS2). These coatings are known to provide low friction in vacuum environments. The goal of this work was to evaluate friction and wear performance of MoS2 doped coatings in unidirectional and reciprocating sliding contact under different environmental conditions. Sliding contact results showed friction and wear dependence on temperature and humidity. The formation and removal of transfer films and the recrystallization and reorientation of basal layers on the steel counterface was observed as the mechanism for low friction. Structural analysis revealed a relationship between the microstructural properties and tribological performance. It was also observed that the addition of dopants (Ti, Au, Sb 2O3) improved the mechanical properties as compared to pure MoS2 coatings. Further, the rolling contact performance of the coatings was measured on a five ball on rod tribometer and a Thrust bearing tribometer under vacuum and air environments. The rolling contact experiments indicated that life of the rolling components depend on the amount of material present between the contacts. Fluid film lubrication with thin film coatings investigates the possibilities to improve the performance and durability of tribological components when oils and thin films are synergistically coupled. In this work, the ability of a Diamond Like Carbon

AMORPHOUS ALLOY SURFACE COATINGS FOR HARD CHROMIUM REPLACEMENT - PHASE I

EPA Science Inventory

Hard chromium coatings (0.25 to10 mil thick) are used extensively for imparting wear and erosion resistance to components in both industrial and military applications. The most common means of depositing hard chromium has been through the use of chromic acid baths containing ...

Spectroscopic Analysis of Perfluoropolyether Lubricant Degradation During Boundary Lubrication

NASA Technical Reports Server (NTRS)

Herrera-Fierro, Pilar; Shogrin, Bradley A.; Jones, William R., Jr.

1996-01-01

The degradation of a branched perfluoropolyether (PFPE) under boundary lubrication conditions was studied using mu-FTIR and mu-Raman spectroscopies. Stainless steel (440C) discs coated with thin (600A), uniform films of the PFPE were tested in a ball-on-disc apparatus until various levels of friction coefficient were attained. Discs were then examined using the above techniques. When the friction coefficient surpassed the value obtained with an un-lubricated control, the lubricant film had either been physically displaced or partially transformed in to a 'friction polymer'. Infrared analysis of this 'friction polymer' indicated the presence of a polymeric fluorinated acid species (R(sub f)COOH). Raman spectroscopy indicated the presence of amorphous carbon in the wear track and in the friction polymer. Some reaction mechanisms are suggested to explain the results.

Process for preparing lubricating oil from used waste lubricating oil

DOEpatents

Whisman, Marvin L.; Reynolds, James W.; Goetzinger, John W.; Cotton, Faye O.

1978-01-01

A re-refining process is described by which high-quality finished lubricating oils are prepared from used waste lubricating and crankcase oils. The used oils are stripped of water and low-boiling contaminants by vacuum distillation and then dissolved in a solvent of 1-butanol, 2-propanol and methylethyl ketone, which precipitates a sludge containing most of the solid and liquid contaminants, unspent additives, and oxidation products present in the used oil. After separating the purified oil-solvent mixture from the sludge and recovering the solvent for recycling, the purified oil is preferably fractional vacuum-distilled, forming lubricating oil distillate fractions which are then decolorized and deodorized to prepare blending stocks. The blending stocks are blended to obtain a lubricating oil base of appropriate viscosity before being mixed with an appropriate additive package to form the finished lubricating oil product.

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.

The tribology of PS212 coatings and PM212 composites for the lubrication of titanium 6Al-4V components of a Stirling engine space power system

NASA Technical Reports Server (NTRS)

Sliney, Harold E.; Lukaszewicz, Victor; Dellacorte, Christopher

1994-01-01

The Stirling space power machine incorporates a linear alternator to generate electrical power. The alternator is a reciprocating device that is driven by a solar or nuclear-powered Stirling engine. The power piston and cylinder are made of titanium 6Al-4V (Ti6-4) alloy, and are designed to be lubricated by a hydrodynamically-generated gas film. Rubbing occurs during starts and stops and there is the possibility of an occasional high speed rub. Since titanium is known to have a severe galling tendency in sliding contacts, a 'back-up', self-lubricating coating on the cylinder and/or the piston is needed. This report describes the results of a research program to study the lubrication of Ti6-4 with the following chromium carbide based materials: plasma-sprayed PS212 coatings and sintered PM212 counterfaces. Program objectives are to achieve adherent coatings on Ti6-4 and to measure the friction and wear characteristics of the following sliding combinations under conditions simulative of the Stirling-driven space power linear alternator: Ti6-4/Ti6-4 baseline, Ti6-4/PS212-coated Ti6-4, and PS212-coated Ti6-4/PM212.

Coated carbide drill performance under soluble coconut oil lubricant and nanoparticle enhanced MQL in drilling AISI P20

NASA Astrophysics Data System (ADS)

Jamil, N. A. M.; Azmi, A. I.; Fairuz, M. A.

2016-02-01

This research experimentally investigates the performance of a TiAlN coated carbide drill bit in drilling AISI P20 through two different kinds of lubricants, namely; soluble coconut oil (SCO) and nanoparticle-enhanced coconut oil (NECO) under minimum quantity lubrication system. The tool life and tool wear mechanism were studied using various cutting speeds of 50, 100 and 150 m/min with a constant feed of 0.01 mm/rev. Since the flank wear land was not regular along the cutting edge, the average flank wear (VB) was measured at several points using image analysis software. The drills were inspected using a scanning electron microscope to further elucidate the wear mechanism. The result indicates that drilling with the nanoparticle- enhanced lubricant was better in resisting the wear and improving the drill life to some extent

A New Antiwear Additive/Surface Pretreatment for PFPE Liquid Lubricants

NASA Technical Reports Server (NTRS)

Morales, Wilfredo; Fusaro, Robert L.; Siebert, Mark; Keith, Theo; Jansen, Ralph; Herrera-Fierro, Pilar

1995-01-01

Pin-on-disk tribology experiments were conducted on a perfluoroalkylelher (PFPE) liquid lubricant with and without a new PFPE lubricant antiwear additive material, a silane. It was found that the silane provided moderate improvement in the antiwear performance of the PFPE lubricant when applied to the metallic surface as a surface coating or when added to the PFPE as a dispersion (emulsion). Slightly better results were obtained by using the combination of a surface coating and an emulsion of the silane. The silane emulsions or coatings did not affect the friction properties of the lubricant. Micro-Fourier transformation infrared (muFTIR) spectroscopy analysis was performed to study silane transfer films and the degradation of the PFPE. The silane was found to mitigate degradation of the PFPE which may have been the major reason for the improved antiwear performance observed.

Lubrication of Space Systems (c)

NASA Technical Reports Server (NTRS)

Fusaro, Robert L.

1995-01-01

This article presents an overview of the current state-of-the-art tribology, some current and future perceived space lubrication problem areas, and some potential new lubrication technologies. It is the author's opinion that tribology technology, in general, has not significantly advanced over the last 20 to 30 years, even though some incremental improvements in the technology have occurred. There is a better understanding of elasto-hydrodynamic lubrication, some new lubricating and wear theories have been developed, and some new liquid and solid lubricants have been formulated. However, the important problems of being able to lubricate reliably at high temperatures or at cryogenic temperatures have not been adequately address.

MS212--A Homogeneous Sputtered Solid Lubricant Coating for Use to 800 C

NASA Technical Reports Server (NTRS)

Sliney, Harold E.; Waters, William J.; Soltis, Richard

1997-01-01

Composite coatings containing chromium carbide, stable fluorides and silver were prepared by magnetron sputtering. The microstructure of the coatings is very homogeneous compared to that of plasma sprayed and sintered versions of the same chemical composition. Friction and wear of MS212-coated and baseline uncoated aluminum and Inconel X-750 are compared. At room temperature, the friction and wear of coated aluminum is dramatically better compared to the baseline. The acceptable load is limited by deformation of the soft aluminum substrate. In the case of the nickel alloy, lower friction is observed for the coated alloy at all temperatures up to the maximum test temperature of 800 C. Pin wear factors for sliding against the coated alloy are lower than the baseline at room temperature and 350 C, and comparable to baseline wear at higher test temperatures. Low baseline wear at high temperatures is due to the lubricious nature of the natural oxides formed on nickel-chromium alloys in a hot, oxidizing atmosphere. No load limit was found for coated Inconel X-750 at loads up to five times the load limit for coated aluminum.

Composition optimization of self-lubricating chromium-carbide-based composite coatings for use to 760 C

NASA Technical Reports Server (NTRS)

Dellacorte, Chris; Sliney, Harold E.

1987-01-01

This paper describes new compositions of self-lubricating coatings that contain chromium carbide. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The coating constituents were treated as a ternary system consisting of: (1) the bonded carbide base material, (2) silver, and (3) the eutectic. A study to determine the optimum amounts of each constituent was performed. The various compositions were prepared by powder blending. The blended powders were then plasma sprayed onto superalloy substrates and diamond ground to the desired coating thickness. Friction and wear studies were performed at temperatures from 25 to 760 C in helium and hydrogen. A variety of counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications such as piston ring/cylinder liner couples for Stirling engines.

Tribological investigation of diamond-like carbon coated micro-dimpled surface under bovine serum and osteoarthritis oriented synovial fluid

PubMed Central

Ghosh, Subir; Choudhury, Dipankar; Roy, Taposh; Bin Mamat, Azuddin; Masjuki, H H; Pingguan-Murphy, Belinda

2015-01-01

Osteoarthritis-oriented synovial fluid (OASF), i.e., that typical of a patient with osteoarthritis, has different physical and biological characteristics than bovine serum (BS), a lubricant widely used in biotribological investigations. Micro-dimpled and diamond-like carbon- (DLC) coated surfaces are key emerging interfaces for orthopedic implants. In this study, tribological performances of dimpled surfaces, with and without DLC coating, have been investigated under both BS and OASF. The friction tests were performed utilizing a pin on a disk tribometer, whereas contact pressure, speed, and temperature were simulated to a ‘medium walking gait’ of hip joint conditions. The mechanical properties of the specimen and the physical properties of the lubricant were characterized before the friction test. Raman analysis was conducted to identify the coating condition both before and after the test. The DLC-coated dimpled surface showed maximum hardness and residual stress. A DLC-coated dimpled surface under an OASF lubricated condition yielded a lower friction coefficient and wear compared to those of plain and dimpled specimens. The higher graphitization of coated materials with increasing load was confirmed by Raman spectroscopy. PMID:27877803

Evaluation of the lubricating effect of magnesium stearate and glyceryl behenate solid lipid nanoparticles in a direct compression process.

PubMed

Martínez-Acevedo, Lizbeth; Zambrano-Zaragoza, María de la Luz; Vidal-Romero, Gustavo; Mendoza-Elvira, Susana; Quintanar-Guerrero, David

2018-05-02

The aim of this study was to develop solid lipid nanoparticles (SLN) and introduce them into a direct compression process to evaluate their lubricant properties. The study consisted of preparing glyceryl behenate SLN (Compritol® 888 ATO) by hot dispersion, and magnesium stearate SLN by a novel nanoprecipitation/ion exchange method. The ejection force was measured for nanosystems and raw materials in a formulation typically used for direct compression. The smallest particle sizes obtained were 456 nm for Compritol® 888 ATO and 330 nm for magnesium stearate. Results show that the NPs used as lubricants in a direct compression model formulation provided efficient lubrication by maintaining the lubricating properties of the system, thereby decreasing the amount of lubricant used compared to the raw material. The lubricating effect showed an increase of 15-30% for magnesium stearate and Compritol® 888 ATO, compared to the raw material at concentrations above 2%. Copyright © 2018 Elsevier B.V. All rights reserved.

Evaluation of the performance during hard turning of OHNS steel with minimal cutting fluid application and its comparison with minimum quantity lubrication

NASA Astrophysics Data System (ADS)

Raj, Anil; Wins, K. Leo Dev; Varadarajan, A. S.

2016-09-01

Cutting fluid application plays a significant role in the manufacturing industries that acts as a coolant as well as a lubricant. The conventional flood cooling application of cutting fluids not only increases the production cost on account of the expenses involved in procurement, storage and disposal but also creates serious environmental and health hazards. In order to overcome these negative effects, techniques like Minimum quantity lubrication (MQL) and Minimal Cutting fluid application (MCFA) have increasingly found their way into the area of metal cutting and have already been established as an alternative to conventional wet machining. This paper investigates the effect of minimal Cutting fluid application (MCFA) which involves application of high velocity pulsing jet of proprietary cutting fluids at the contact zones using a special fluid application system. During hard turning of oil hardened non shrinkable steel (OHNS) on cutting temperature and tool wear and to compare the performance with Minimum quantity lubrication (MQL) assisted hard turning in which cutting fluid is carried in a high velocity stream of air. An attempt was also made to compare the performance during Turning with MCFA and MQL application with conventional wet and dry turning by analysing the tool wear pattern using SEM images.

The production and tribology of hard facing coatings for agricultural applications

NASA Astrophysics Data System (ADS)

Roffey, Paul

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

Intermetallic Nickel-Titanium Alloys for Oil-Lubricated Bearing Applications

NASA Technical Reports Server (NTRS)

DellaCorte, C.; Pepper, S. V.; Noebe, R.; Hull, D. R.; Glennon, G.

2009-01-01

An intermetallic nickel-titanium alloy, NITINOL 60 (60NiTi), containing 60 wt% nickel and 40 wt% titanium, is shown to be a promising candidate material for oil-lubricated rolling and sliding contact applications such as bearings and gears. NiTi alloys are well known and normally exploited for their shape memory behavior. When properly processed, however, NITINOL 60 exhibits excellent dimensional stability and useful structural properties. Processed via high temperature, high-pressure powder metallurgy techniques or other means, NITINOL 60 offers a broad combination of physical properties that make it unique among bearing materials. NITINOL 60 is hard, electrically conductive, highly corrosion resistant, less dense than steel, readily machined prior to final heat treatment, nongalling and nonmagnetic. No other bearing alloy, metallic or ceramic encompasses all of these attributes. Further, NITINOL 60 has shown remarkable tribological performance when compared to other aerospace bearing alloys under oil-lubricated conditions. Spiral orbit tribometer (SOT) tests were conducted in vacuum using NITINOL 60 balls loaded between rotating 440C stainless steel disks, lubricated with synthetic hydrocarbon oil. Under conditions considered representative of precision bearings, the performance (life and friction) equaled or exceeded that observed with silicon nitride or titanium carbide coated 440C bearing balls. Based upon this preliminary data, it appears that NITINOL 60, despite its high titanium content, is a promising candidate alloy for advanced mechanical systems requiring superior and intrinsic corrosion resistance, electrical conductivity and nonmagnetic behavior under lubricated contacting conditions.

Tribological coatings for complex mechanical elements produced by supersonic cluster beam deposition of metal dichalcogenide nanoparticles

NASA Astrophysics Data System (ADS)

Piazzoni, C.; Buttery, M.; Hampson, M. R.; Roberts, E. W.; Ducati, C.; Lenardi, C.; Cavaliere, F.; Piseri, P.; Milani, P.

2015-07-01

Fullerene-like MoS2 and WS2 nanoparticles can be used as building blocks for the fabrication of fluid and solid lubricants. Metal dichalcogenide films have a very low friction coefficient in vacuum, therefore they have mostly been used as solid lubricants in space and vacuum applications. Unfortunately, their use is significantly hampered by the fact that in the presence of humidity, oxygen and moisture, the low-friction properties of these materials rapidly degrade due to oxidation. The use of closed-cage MoS2 and WS2 nanoparticles may eliminate this problem, although the fabrication of lubricant thin films starting from dichalcogenide nanoparticles is, to date, a difficult task. Here we demonstrate the use of supersonic cluster beam deposition for the coating of complex mechanical elements (angular contact ball bearings) with nanostructured MoS2 and WS2 thin films. We report structural and tribological characterization of the coatings in view of the optimization of tribological performances for aerospace applications.

The tribology of PS212 coatings and PM212 composites for the lubrication of titanium 6A1-4V components of a Stirling engine space power system

NASA Technical Reports Server (NTRS)

Sliney, Harold E.; Dellacorte, Christopher; Lukaszewicz, Victor

1995-01-01

The Stirling space power machine incorporates a linear alternator to generate electrical power. The alternator is a reciprocating device that is driven by a solar or nuclear-powered Stirling engine. The power piston and cylinder are made of titanium 6A1-4V (Ti6-4) alloy, and are designed to be lubricated by a hydrodynamically-generated gas film. Rubbing occurs during starts and stops and there is a possibility of an occasional high speed rub. Since titanium is known to have a severe galling tendency in sliding contacts, a 'backup,' self-lubricating coating on the cylinder and/or the piston is needed. This report describes the results of a research program to study the lubrication of Ti6-4 with the following chromium carbide based materials: plasma-sprayed PS212 coatings and sintered PM212 counterfaces. Program objectives are to achieve adherent coatings on Ti6-4 and to measure the friction and wear characteristics of the following sliding combinations under conditions simulative of the Stirling-driven space power linear alternator: Ti6-4/Ti6-4 baseline, Ti6-4/PS212 coated Ti6-4, and Ps212 coated Ti6-4/PM212

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.

Engine Lubricant

NASA Technical Reports Server (NTRS)

1993-01-01

PS 212, a plasma-sprayed coating developed by NASA, is used to coat valves in a new rotorcam engine. The coating eliminates the need for a liquid lubricant in the rotorcam, which has no crankshaft, flywheel, distributor or water pump. Developed by Murray United Development Corporation, it is a rotary engine only 10 inches long with four cylinders radiating outward from a central axle. Company officials say the engine will be lighter, more compact and cheaper to manufacture than current engines and will feature cleaner exhaust emissions. A licensing arrangement with a manufacturer is under negotiation. Primary applications are for automobiles, but the engine may also be used in light aircraft.

Technology Exploitation/Exploration/Examination Report (TeX3): Adaptive Self-Lubricating Nanoporous Hard Coatings

DTIC Science & Technology

2008-04-01

Technology, 167 (2003) 25. 14. T. Polcar, N.M.G. Parreira, R . Novak, Surface and Coatings Technology, 201 (2007) 5228. 15. H.C. Barshilia, N. Selvakumar ...Sodergren, D. Mihut, S. L. Rohde, J. Xu, S. R . Mishra, Surface and Coatings Technology, 201 (2006) 418. 9. A.A. Voevodin, J.J. Hu, T.A. Fitz, J.S

Friction and Wear Behavior of Plasma-Sprayed Al2O3-13 wt.%TiO2 Coatings Under the Lubrication of Liquid Paraffin

NASA Astrophysics Data System (ADS)

Zhao, Xiaoqin; An, Yulong; Hou, Guoliang; Zhou, Huidi; Chen, Jianmin

2014-04-01

Two types of ceramic composite coatings (denoted as N-AT13 coating and M-AT13 coating) were fabricated on 1Cr18Ni9Ti stainless steel substrate from ultra-fine and coarse Al2O3-13%TiO2 feedstocks by air plasma spraying. The friction and wear behavior of as-prepared coatings sliding against Al2O3 and stainless steel balls under the lubrication of liquid paraffin was evaluated with an SRV friction and wear tester (Optimol, Germany). The fractured and worn surfaces of the coatings were observed using a scanning electron microscope and a field-emission scanning electron microscope; and the wear mechanisms of the coatings were discussed based on scanning electron microscopic analysis and energy dispersive spectrometric analysis. Results show that N-AT13 coating possesses a unique microstructure and strong inter-splat bonding, thereby showing increased microhardness and bonding strength as well as much better friction-reduction and wear resistance than M-AT13 coating. Moreover, there exist differences in the wear mechanisms of N-AT13 and M-AT13 coatings which slide against ceramic and stainless steel balls under the lubrication of liquid paraffin. Namely, with the increase of normal load, the burnishing of N-AT13 coating coupled with Al2O3 ball is gradually transformed to grain-abrasion and deformation, while M-AT13 coating is dominated by grain-pullout and brittle fracture in the whole range of tested normal load.

A novel method to predict the highest hardness of plasma sprayed coating without micro-defects

NASA Astrophysics Data System (ADS)

Zhuo, Yukun; Ye, Fuxing; Wang, Feng

2018-04-01

The plasma sprayed coatings are stacked by splats, which are regarded generally as the elementary units of coating. Many researchers have focused on the morphology and formation mechanism of splat. However, a novel method to predict the highest hardness of plasma sprayed coating without micro-defects is proposed according to the nanohardness of splat in this paper. The effectiveness of this novel method was examined by experiments. Firstly, the microstructure of splats and coating, meanwhile the 3D topography of the splats were observed by SEM (SU1510) and video microscope (VHX-2000). Secondly, the nanohardness of splats was evaluated by nanoindentation (NHT) in order to be compared with microhardness of coating measured by microhardness tester (HV-1000A). The results show that the nanohardness of splats with diameter of 70 μm, 100 μm and 140 μm were in the scope of 11∼12 GPa while the microhardness of coating were in the range of 8∼9 GPa. Because the splats had not micro-defects such as pores and cracks in the nanohardness evaluated nano-zone, the nanohardness of the splats can be utilized to predict the highest hardness of coating without micro-defects. This method indicates the maximum of sprayed coating hardness and will reduce the test number to get high hardness coating for better wear resistance.

Enhancement of Perfluoropolyether Boundary Lubrication Performance

NASA Technical Reports Server (NTRS)

Jones, W. R., Jr.; Ajayi, O. O.; Wedeven, L. D.

1996-01-01

A ball bearing simulator operating under starved conditions was used to perform screening tests to evaluate the boundary lubrication performance of a branched perfluoropolyether (PFPE), K-143 AB. Several approaches to enhance boundary lubrication were studied. These included: (1) soluble boundary additives, (2) bearing surface modifications, (3) 'run-in' surface films, and (4) ceramic bearing components. In addition, results were compared with two non-perfluorinated liquid lubricant formulations. Based on these tests, the following tentative conclusions can be made: (1) Substantial improvements in boundary lubrication performance were observed with a beta-diketone boundary additive and a tricresyl phosphate (TCP) liquid surface pretreatment, (2) the use of rough Si3N4 balls (R(sub a) = 40 micro-inch) also provided increases in test duration, but with concomitant abrasive wear, (3) moderate improvements were seen with two boundary additives (a phosphine and a phosphatriazine) and a neat (100%) fluid (a carboxylic acid terminated PFPE); and small improvements with surface pretreatments with synthetic hydrocarbons, a polytetrafluoroethylene (PTFE) coating, and TiC coated 440 C and smooth Si3N4 balls (R(sub a) = 1 micro-inch), and (4) two non-PFPE lubricant formulations (a polyalphaolefin (PAO) and synthetic hydrocarbon) yielded substantial improvements.

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.

Plasma-sprayed, self-lubricating coatings for use from cryogenic temperatures to 870 deg C (1600 deg F)

NASA Technical Reports Server (NTRS)

Sliney, H. E.

1975-01-01

A plasma-sprayed coating is described with good lubricating properties over a wide temperature range. The coating, designated NASA LUBE PS101, contains silver, nichrome, calcium fluoride, and an oxidation protective glass. Oscillating tests were conducted of self-aligning, plain cylindrical bearings, in which the bore was lined with 0.025 cm (0.010 in.) thick coatings of PS101; these were conducted at a radial load of 3.5 x 10 to the 7th power N/sq m (5000 psi) in nitrogen gas at -107 C (-160 F), in vacuum at room temperature, and in air from room temperature to 870 C (1600 F). Friction coefficients were less than 0.25 in all cases and wear rates were low. The coating is not brittle, and it has adequate oxidation resistance in air to at least 870 C.

Dairy Equipment Lubrication

NASA Technical Reports Server (NTRS)

1978-01-01

Lake To Lake Dairy Cooperative, Manitowoc, Wisconsin, operates four plants in Wisconsin for processing milk, butter and cheese products from its 1,300 member farms. The large co-op was able to realize substantial savings by using NASA information for improved efficiency in plant maintenance. Under contract to Marshall Space Flight Center, Midwest Research Institute compiled a handbook consolidating information about commercially available lubricants. The handbook details chemical and physical properties, applications, specifications, test procedures and test data for liquid and solid lubricants. Lake To Lake's plant engineer used the handbook to effect savings in maintenance labor and materials costs by reducing the number of lubricants used on certain equipment. Strict U.S. Department of Agriculture and Food and Drug Administration regulations preclude lubrication changes n production equipment, but the co-op's maintenance chief was able to eliminate seven types of lubricants for ancillary equipment, such as compressors and high pressure pumps. Handbook data enabled him to select comparable but les expensive lubricants in the materials consolidation process, and simplified lubrication schedules and procedures. The handbook is in continuing use as a reference source when a new item of equipment is purchased.

Vapor/Mist Used to Lubricate Gears After Loss of Primary Lubrication System

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.; Morales, Wilfredo

2001-01-01

Loss of lubrication in rotorcraft drive systems is a demanding requirement placed on drive system manufacturers. The drive system must operate for at least 30 minutes once the primary lubrication system has failed. This test is a military requirement that must be passed prior to certification of the aircraft. As new aircraft engines, operating at higher speeds, are fielded, the requirements for the drive system become increasingly more difficult. Also, the drive system must be lightweight, which minimizes the opportunity to use the gear bodies to absorb the tremendous amount of heating that takes place. In many cases, the amount of heat generated because of the high speed and load requires an emergency lubrication system that negatively impacts the aircraft's weight, complexity, and cost. A single mesh spur gear test rig is being used at the NASA Glenn Research Center to investigate possible emergency lubrication system improvements that will minimize the impact of having these systems onboard rotorcraft. A technique currently being investigated uses a vapor/mist system to lubricate the contacting surfaces after the primary lubrication system has been shut down. A number of tests were conducted in which the vapor/mist used the same lubricant as the primary system, but at a greatly reduced flow rate. Each test was initiated with the primary lubrication system operational and at steady-state conditions for a given speed and load. Then the primary lubrication system was shut down, and the vapor/mist lubrication system was initiated. An example of the tests conducted is shown in the figures. These preliminary tests have uncovered a mechanism that provides a lubricious, carbonaceous solid on the surface that actually reduces the surface temperature of the meshing gear teeth during operation. Surface analysis of the carbonaceous solid revealed it was graphitic. This mechanism is the synthetic lubricant "coking" on the active profile of the gears, which reduces the

Composition optimization of self-lubricating chromium carbide-based composite coatings for use to 760 deg C

NASA Technical Reports Server (NTRS)

Dellacorte, C.; Sliney, H. E.

1986-01-01

This paper describes new compositions of self-lubricating coatings that contain chromium carbide. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The coating constituents were treated as a ternary system consisting of: (1) the bonded carbide base material, (2) silver, and (3) the eutectic. A study to determine the optimum amounts of each constituent was performed. The various compositions were prepared by powder blending. The blended powders were then plasma sprayed onto superalloy substrates and diamond ground to the desired coating thickness. Friction and wear studies were performed at temperatures from 25 to 760 C in helium and hydrogen. A variety of counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications such as piston ring/cylinder liner couples for Stirling engines.

Lubricant Selection Manual, Phase 3

NASA Technical Reports Server (NTRS)

Kannel, J. W.; Lowry, J. A.; Dufrane, K. F.

1991-01-01

Future spacecraft must be designated to operate for very long time periods in space. For example, a target goal for the Space Station is 30 years of operation. Although the actual life may be significantly less than this optimistic goal, the life will certainly be a critical issue in design. The bearings on primary components such as the alpha and beta joints must obviously be designed and lubricated with the objective of optimum performance life. In addition to these joints, there will be numerous other tribological (rubbing or rolling) interfaced that will be required to function for the life of the spacecraft. A major key to adequate performance of tribological interface is proper lubrication. Lubricants can be divided into two basic classes: solid films and liquids. Both types have been used extensively in space applications. Both have advantages and disadvantages that must be carefully considered in their selection. The purpose here is to summarize selection criteria for liquid and solid lubricants applied to long-life spacecraft.

Non-equilibrium responses of PFPE lubricants with various atomistic/molecular architecture at elevated temperature

NASA Astrophysics Data System (ADS)

Chung, Pil Seung; Song, Wonyup; Biegler, Lorenz T.; Jhon, Myung S.

2017-05-01

During the operation of hard disk drive (HDD), the perfluoropolyether (PFPE) lubricant experiences elastic or viscous shear/elongation deformations, which affect the performance and reliability of the HDD. Therefore, the viscoelastic responses of PFPE could provide a finger print analysis in designing optimal molecular architecture of lubricants to control the tribological phenomena. In this paper, we examine the rheological responses of PFPEs including storage (elastic) and loss (viscous) moduli (G' and G″) by monitoring the time-dependent-stress-strain relationship via non-equilibrium molecular dynamics simulations. We analyzed the rheological responses by using Cox-Merz rule, and investigated the molecular structural and thermal effects on the solid-like and liquid-like behaviors of PFPEs. The temperature dependence of the endgroup agglomeration phenomena was examined, where the functional endgroups are decoupled as the temperature increases. By analyzing the relaxation processes, the molecular rheological studies will provide the optimal lubricant selection criteria to enhance the HDD performance and reliability for the heat-assisted magnetic recording applications.

Development of High Resolution Hard X-Ray Telescope with Multilayer Coatings

NASA Technical Reports Server (NTRS)

Brinton, John C. (Technical Monitor); Gorenstein, Paul

2004-01-01

The major objective of this program is the development of a focusing hard X-ray telescope with moderately high angular resolution, i .e. comparable to the telescopes of XMM-Newton. The key ingredients of the telescope are a depth graded multilayer coatings and electroformed nickel substrates that are considerably lighter weight than those of previous missions such as XMM-Newton, which have had conventional single metal layer reflective coatings and have operated at much lower energy X-rays. The ultimate target mission for this technology is the Hard X-Ray Telescope (HXT) of the Constellation X-Ray Mission. However, it is applicable to potential SMEX and MIDEX programs as well.

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.

Does the Use of Diamond-Like Carbon Coating and Organophosphate Lubricant Additive Together Cause Excessive Tribochemical Material Removal?

DOE PAGES

Zhou, Yan; Leonard, Donovan N.; Meyer, Harry M.; ...

2015-08-22

We observe unexpected wear increase on a steel surface that rubbed against diamond-like carbon (DLC) coatings only when lubricated by phosphate-based antiwear additives. Contrary to the literature hypothesis of a competition between zinc dialkyldithiophosphate produced tribofilms and DLC-induced carbon transfer, here a new wear mechanism based on carbon-catalyzed tribochemical interactions supported by surface characterization is proposed

Phosphate Reactions as Mechanisms of High-Temperature Lubrication

NASA Technical Reports Server (NTRS)

Nagarajan, Anitha; Garrido, Carolina; Gatica, Jorge E.; Morales, Wilfredo

2006-01-01

One of the major problems preventing the operation of advanced gas turbine engines at higher temperatures is the inability of currently used liquid lubricants to survive at these higher temperatures under friction and wear conditions. Current state-of-the-art organic liquid lubricants rapidly degrade at temperatures above 300 C; hence some other form of lubrication is necessary. Vapor-phase lubrication is a promising new technology for high-temperature lubrication. This lubrication method employs a liquid phosphate ester that is vaporized and delivered to bearings or gears; the vapor reacts with the metal surfaces, generating a solid lubricious film that has proven very stable at high temperatures. In this study, solid lubricious films were grown on cast-iron foils in order to obtain reaction and diffusion rate data to help characterize the growth mechanism. A phenomenological mathematical model of the film deposition process was derived incorporating transport and kinetic parameters that were coupled to the experimental data. This phenomenological model can now be reliably used as a predictive and scale-up tool for future vapor-phase lubrication studies.

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.

Au/Cr Sputter Coating for the Protection of Alumina During Sliding at High Temperatures

NASA Technical Reports Server (NTRS)

Benoy, Patricia A.; Dellacorte, Christopher

1995-01-01

A sputter deposited bilayer coating of gold and chromium was investigated as a potential solid lubricant to protect alumina substrates in applications involving sliding at high temperature. The proposed lubricant was tested in a pin-on-disk tribometer with coated alumina disks sliding against uncoated alumina pins. Three test parameters; temperature, load, and sliding velocity were varied over a wide range in order to determine the performance envelope on the gold/chromium (Au/Cr) solid lubricant film. The tribo-tests were run in an air atmosphere at temperatures of 25 to 1000 C, under loads of 4.9 to 49.0 N and at sliding velocities from 1 to 15 m/sec. Post test analyses included surface profilometry, wear factor determination and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) examination of worn surfaces. Compared to unlubricated Al2O3 sliding, the use of the Au/Cr film reduced friction by 30 to 50 percent and wear by one to two orders of magnitude. Increases in test temperature resulted in lower friction and the Au/Cr film continued to provide low friction, about 0.3, even at 1000 C. Pin wear factors and friction were largely unaffected by increasing loads up to 29.4 N. Sliding velocity had essentially no effect on friction, however, increased velocity reduced coating life (total sliding distance). Based upon these research results, the Au/Cr film is a promising lubricant for moderately loaded, low speed applications operating at temperatures as high as 1000 C.

Analysis of Minimum Quantity Lubrication (MQL) for Different Coating Tools during Turning of TC11 Titanium Alloy.

PubMed

Qin, Sheng; Li, Zhongquan; Guo, Guoqiang; An, Qinglong; Chen, Ming; Ming, Weiwei

2016-09-28

The tool coating and cooling strategy are two key factors when machining difficult-to-cut materials such as titanium alloy. In this paper, diamond coating was deposited on a commercial carbide insert as an attempt to increase the machinability of TC11 alloy during the turning process. An uncoated carbide insert and a commercial Al₂O₃/TiAlN-coated tool were also tested as a comparison. Furthermore, MQL was applied to improve the cutting condition. Cutting performances were analyzed by cutting force, cutting temperate and surface roughness measurements. Tool wears and tool lives were evaluated to find a good matchup between the tool coating and cooling strategy. According to the results, using MQL can slightly reduce the cutting force. By applying MQL, cutting temperatures and tool wears were reduced by a great amount. Besides, MQL can affect the tool wear mechanism and tool failure modes. The tool life of an Al₂O₃/TiAlN-coated tool can be prolonged by 88.4% under the MQL condition. Diamond-coated tools can obtain a good surface finish when cutting parameters and lubrication strategies are properly chosen.

Analysis of Minimum Quantity Lubrication (MQL) for Different Coating Tools during Turning of TC11 Titanium Alloy

PubMed Central

Qin, Sheng; Li, Zhongquan; Guo, Guoqiang; An, Qinglong; Chen, Ming; Ming, Weiwei

2016-01-01

The tool coating and cooling strategy are two key factors when machining difficult-to-cut materials such as titanium alloy. In this paper, diamond coating was deposited on a commercial carbide insert as an attempt to increase the machinability of TC11 alloy during the turning process. An uncoated carbide insert and a commercial Al2O3/TiAlN-coated tool were also tested as a comparison. Furthermore, MQL was applied to improve the cutting condition. Cutting performances were analyzed by cutting force, cutting temperate and surface roughness measurements. Tool wears and tool lives were evaluated to find a good matchup between the tool coating and cooling strategy. According to the results, using MQL can slightly reduce the cutting force. By applying MQL, cutting temperatures and tool wears were reduced by a great amount. Besides, MQL can affect the tool wear mechanism and tool failure modes. The tool life of an Al2O3/TiAlN-coated tool can be prolonged by 88.4% under the MQL condition. Diamond-coated tools can obtain a good surface finish when cutting parameters and lubrication strategies are properly chosen. PMID:28773926

Preparation, Microstructure and Performance of Nanoscale Ceramics Reinforced Hard Composite Coating

NASA Astrophysics Data System (ADS)

Li, Peng

2014-11-01

This paper is based on the dry sliding wear of Stellite SF12-B4C-TiN-Mo composite coating deposited on a pure Ti using a laser cladding technique, the parameters of which provide almost crack-free composites with low porosity. To the best of our knowledge, it is the first time that Stellite SF12-B4C-TiN-Mo mixed powders are deposited as the hard composites by a laser cladding technique. Scanning electron microscope images indicate that the nanoscale particles are produced in such coating. The fact that due to the sufficiently rapid heating and cooling rates of the laser cladding technique, the ceramics, such as TiC or TiB2 did not have enough time to grow up, resulting in the formation of the nanoscale particles. Compared with a pure Ti substrate, the increments of the micro-hardness and wear resistance are obtained for such composite coating.

The Effect of Stress and TiC Coated Balls on Lubricant Lifetimes Using a Vacuum Ball-on-Plate Rolling Contact Tribometer

NASA Technical Reports Server (NTRS)

Jones, William R., Jr.; Jansen, Mark J.; Helmick, Larry H.; Nguyen, QuynhGiao; Wheeler, Donald R.; Voving, Hans J.

1999-01-01

A vacuum ball-on-plate rolling contact tribometer was used to determine the relative lifetimes of a perfluoropolyether (Krytox 143 AC) on 440C stainless steel. The effect of mean Hertzian stresses (0.75, 1.0, 1.5 and 2.0 GPa) and the use of TiC coated balls on lubricant lifetime was studied. Other conditions included: approximately 100 rpm, approximately 50 micrograms of lubricant, an initial vacuum level of less than 1.0 x 1O(exp -8) Torr, and room temperature (approximately 23 C). increasing the mean Hertzian stress from 0.75 to 2.0 GPa results in an exponential decrease in lubricant lifetime for both material combinations. However. substituting a TiC ball for the 440C ball quadrupled lifetime at low stress levels (0.75 and 1.0 GPa) and doubled life at higher stresses (1.5 and 2.0 GPa). The reduced reactivity of the TiC surface with the PFPE lubricant is considered to be the reason for this enhancement. Decreasing lifetime with increasing stress levels correlated well with energy dissipation calculations.

The Effect of Stress and TiC Coated Balls on Lubricant Lifetimes Using a Vacuum Ball-on-Plate Rolling Contact Tribometer

NASA Technical Reports Server (NTRS)

Jones, William R., Jr.; Jansen, Mark J.; Helmick, Larry H.; Nguyen, QuynhGiao; Wheeler, Donald R.; Boving, Hans J.

1999-01-01

A vacuum ball-on-plate rolling contact tribometer was used to determine the relative lifetimes of a perfluoropolyether (Krytox 143 AC) on 440C stainless steel. The effect of mean Hertzian stresses (0.75, 1.0, 1.5, and 2.0 GPa) and the use of TiC-coated balls on lubricant lifetime was studied. Other conditions included: 100 rpm, 50 micro-g of lubricant, an initial vacuum level of less than 1.0 x 10(exp -8) Torr, and room temperature (23 C). Increasing the mean Hertzian stress from 0.75 to 2.0 GPa results in an exponential decrease in lubricant lifetime for both material combinations. However, substituting a TiC ball for the 440C ball quadrupled lifetime at low stress levels (0.75 and 1.0 GPa) and doubled life at higher stresses (1.5 and 2.0 GPa). The reduced reactivity of the TiC surface with the PFPE lubricant is considered to be the reason for this enhancement. Decreasing lifetime with increasing stress levels correlated well with energy dissipation calculations.

Quality control of the tribological coating PS212

NASA Technical Reports Server (NTRS)

Sliney, Harold E.; Dellacorte, Christopher; Deadmore, Daniel L.

1989-01-01

PS212 is a self-lubricating, composite coating that is applied by the plasma spray process. It is a functional lubricating coating from 25 C (or lower) to 900 C. The coating is prepared from a blend of three different powders with very dissimilar properties. Therefore, the final chemical composition and lubricating effectiveness of the coatings are very sensitive to the process variables used in their preparation. Defined here are the relevant variables. The process and analytical procedures that will result in satisfactory tribological coatings are discussed.

Lubrication of chocolate during oral processing.

PubMed

Rodrigues, S A; Selway, N; Morgenstern, M P; Motoi, L; Stokes, J R; James, B J

2017-02-22

The structure of chocolate is drastically transformed during oral processing from a composite solid to an oil/water fluid emulsion. Using two commercial dark chocolates varying in cocoa solids content, this study develops a method to identify the factors that govern lubrication in molten chocolate and saliva's contribution to lubrication following oral processing. In addition to chocolate and its individual components, simulated boluses (molten chocolate and phosphate buffered saline), in vitro boluses (molten chocolate and whole human saliva) and ex vivo boluses (chocolate expectorated after chewing till the point of swallow) were tested. The results reveal that the lubrication of molten chocolate is strongly influenced by the presence of solid sugar particles and cocoa solids. The entrainment of particles into the contact zone between the interacting surfaces reduces friction such that the maximum friction coefficient measured for chocolate boluses is much lower than those for single-phase Newtonian fluids. The addition of whole human saliva or a substitute aqueous phase (PBS) to molten chocolate dissolves sugar and decreases the viscosity of molten chocolate so that thinner films are achieved. However, saliva is more lubricating than PBS, which results in lower friction coefficients for chocolate-saliva mixtures when compared to chocolate-PBS mixtures. A comparison of ex vivo and in vitro boluses also suggests that the quantity of saliva added and uniformity of mixing during oral processing affect bolus structure, which leads to differences in measured friction. It is hypothesized that inhomogeneous mixing in the mouth introduces large air bubbles and regions of non-emulsified fat into the ex vivo boluses, which enhance wetting and lubrication.

Possible alternatives to critical elements in coatings for extreme applications

NASA Astrophysics Data System (ADS)

Grilli, Maria Luisa; Valerini, Daniele; Piticescu, Radu Robert; Bellezze, Tiziano; Yilmaz, Mehmet; Rinaldi, Antonio; Cuesta-López, Santiago; Rizzo, Antonella

2018-03-01

Surface functionalisation and protection have been used since a long time for improving specific properties of materials such as lubrication, water repellence, brightness, and for increasing durability of objects and tools. Among the different kinds of surface treatments used to achieve the required properties, the use of coatings is fundamental to guarantee substrate durability in harsh environments. Extreme working conditions of temperature, pressure, irradiation, wear and corrosion occur in several applications, thus very often requiring bulk material protection by means of coatings. In this study, three main classes of coatings used in extreme conditions are considered: i) hard and superhard coatings for application in machining tools, ii) coatings for high temperatures (thermal barrier coatings), and iii) coatings against corrosion. The presence of critical elements in such coatings (Cr, Y, W, Co, etc.) is analysed and the possibility to use CRMs-free substitutes is reviewed. The role of multilayers and nanocomposites in tailoring coating performances is also discussed for thermal barrier and superhard coatings.

Preparation and Tribological Study of Biodegradable Lubrication Films on Si Substrate

PubMed Central

Shi, Shih-Chen; Huang, Teng-Feng; Wu, Jhen-Yu

2015-01-01

A novel method for preparing eco-biodegradable lubricant based on hydroxypropyl methylcellulose (HPMC) via hydration process is demonstrated. The smooth and homogeneous HPMC coating has a uniform thickness (~35 μm). It has been demonstrated that the preparation parameters play a critical role in controlling the lubricating behavior of the coating; in addition, excess HPMC and water concentration suppress the tribology properties. Nevertheless, a remarkable friction-reduction and anti-wear performance has been obtained. Impressively, the preparation parameter of 5% HPMC + 30 mL water significantly improves lubricant performance and durability. A simple approach for the water-degradability evaluation of HPMC is proposed. PMID:28788029

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.

Enhancement of perfluoropolyether boundary lubrication performance: I. Preliminary results

NASA Technical Reports Server (NTRS)

Jones, W. R., Jr.; Ajayi, O. O.; Goodell, A. J.; Wedeven, L. D.; Devine, E.; Premore, R. E.

1995-01-01

A ball bearing simulator operating under starved conditions was used to evaluate the boundary lubrication performance of a perfluoropolyether (PFPE) Krytox 143 AB. Several approaches to enhance boundary lubrication were studied. These included: (1) soluble boundary additives, (2) bearing surface modifications, (3) 'run-in' surface films, and (4) ceramic bearing components. In addition, results were compared with two non-perfluorinated liquid lubricant formulations. Based on these preliminary tests, the following tentative conclusions can be made: (1) substantial improvements in boundary lubrication performance were observed with a beta-diketone boundary additive and a tricresyl phosphate (TCP) liquid surface pretreatment; (2) the use of rough Si3N4 balls (Ra = 40 micro-in) also provided substantial improvement but with concomitant abrasive wear; (3) marginal improvements were seen with two boundary additives (a phosphine and a phosphatriazine) and a neat (100%) fluid (a carboxylic acid terminated PFPE); and surface pretreatments with a synthetic hydrocarbon, a PTFE coating, and TiC coated 440C and smooth Si3N4 balls (R(sub a) less than 1 micro-in); and (4) two non-PFPE lubricant formulations (a PAO and a synthetic hydrocarbon) yielded substantial improvements.

Hard and flexible nanocomposite coatings using nanoclay-filled hyperbranched polymers.

PubMed

Fogelström, Linda; Malmström, Eva; Johansson, Mats; Hult, Anders

2010-06-01

The combination of hardness, scratch resistance, and flexibility is a highly desired feature in many coating applications. The aim of this study is to achieve this through the introduction of an unmodified nanoclay, montmorillonite (Na(+)MMT), in a polymer resin based on the hyperbranched polyester Boltorn H30. Smooth and transparent films were prepared from both the neat and the nanoparticle-filled hyperbranched resins. X-ray diffraction (XRD) and transmission electron microscopy (TEM) corroborated a mainly exfoliated structure in the nanocomposite films, which was also supported by results from dynamic mechanical analysis (DMA). Furthermore, DMA measurements showed a 9-16 degrees C increase in Tg and a higher storage modulus-above and below the T(g)-both indications of a more cross-linked network, for the clay-containing film. Thermogravimetric analysis (TGA) demonstrated the influence of the nanofiller on the thermal properties of the nanocomposites, where a shift upward of the decomposition temperature in oxygen atmosphere is attributed to the improved barrier properties of the nanoparticle-filled materials. Conventional coating characterization methods demonstrated an increase in the surface hardness, scratch resistance and flexibility, with the introduction of clay, and all coatings exhibited excellent chemical resistance and adhesion.

The hardness of the hydroxyapatite-titania bilayer coatings by microindentation and nanoindentation testing

NASA Astrophysics Data System (ADS)

SIDANE, Djahida; KHIREDDINE, Hafit; YALA, Sabeha

2017-12-01

The aim of this paper is to investigate the effect of the addition of titania (TiO2) inner-layer on the morphological and mechanical properties of hydroxyapatite (HAP) bioceramic coatings deposited on 316L stainless steel (316L SS) by sol-gel method in order to improve the properties of hydroxyapatite and expand its clinical application. The addition of TiO2 as sublayer of a hydroxyapatite coating results in changes in surface morphology as well as an increase of the microhardness. The deposition of the inner-layer provides the formation of new types of hydroxyapatite coatings at the same condition of annealing. This represents an advantage for the various applications of the hydroxyapatite bioceramic in the medical field. Classical hardness measurements conducted on the coated systems under the same indentation load (10g) indicated that the microhardness of the HAP coating is improved by the addition of TiO2 inner-layer on the 316L stainless steel substrate. The hardness values obtained from both classical tests in microindentation and the continuous stiffness measurement mode in nanoindentation are slightly different. This is because nanoindentation is more sensitive to the surface roughness and the influence of defects that could be present into the material. Moreover, nanoindentation is the most useful method to separate the contribution of each layer in the bilayer coatings. In this study, the hardness is comparable with those reported previously for pure HAP ceramics (1.0-5.5 GPa) which are close to the properties of natural teeth.

Glass microsphere lubrication

NASA Technical Reports Server (NTRS)

Geiger, Michelle; Goode, Henry; Ohanlon, Sean; Pieloch, Stuart; Sorrells, Cindy; Willette, Chris

1991-01-01

The harsh lunar environment eliminated the consideration of most lubricants used on earth. Considering that the majority of the surface of the moon consists of sand, the elements that make up this mixture were analyzed. According to previous space missions, a large portion of the moon's surface is made up of fine grained crystalline rock, about 0.02 to 0.05 mm in size. These fine grained particles can be divided into four groups: lunar rock fragments, glasses, agglutinates (rock particles, crystals, or glasses), and fragments of meteorite material (rare). Analysis of the soil obtained from the missions has given chemical compositions of its materials. It is about 53 to 63 percent oxygen, 16 to 22 percent silicon, 10 to 16 percent sulfur, 5 to 9 percent aluminum, and has lesser amounts of magnesium, carbon, and sodium. To be self-supporting, the lubricant must utilize one or more of the above elements. Considering that the element must be easy to extract and readily manipulated, silicon or glass was the most logical choice. Being a ceramic, glass has a high strength and excellent resistance to temperature. The glass would also not contaminate the environment as it comes directly from it. If sand entered a bearing lubricated with grease, the lubricant would eventually fail and the shaft would bind, causing damage to the system. In a bearing lubricated with a solid glass lubricant, sand would be ground up and have little effect on the system. The next issue was what shape to form the glass in. Solid glass spheres was the only logical choice. The strength of the glass and its endurance would be optimal in this form. To behave as an effective lubricant, the diameter of the spheres would have to be very small, on the order of hundreds of microns or less. This would allow smaller clearances between the bearing and the shaft, and less material would be needed. The production of glass microspheres was divided into two parts, production and sorting. Production includes the

Effect of pH, Surfactant, and Heat Treatment on Morphology, Structure, and Hardness of Electrodeposited Co-P Coatings

NASA Astrophysics Data System (ADS)

Zeinali-Rad, M.; Allahkaram, S. R.; Mahdavi, S.

2015-09-01

Nano-crystalline and amorphous Co-P coatings were deposited on plain carbon steel substrates by using direct current. Effects of electrolyte pH on morphology, current efficiency, phosphorus content, hardness, and preferred orientation of the nano-crystalline coatings were investigated. Moreover, the effects of heat treatment on microstructure and hardness of the nano-crystalline and the amorphous coatings were studied. The results showed that, phosphorus content and hardness of the nano-crystalline coatings were decreased by increasing of the pH, in spite of a current efficiency enhancement to as much as 98%. Grain size and preferred orientation were also changed from 13 to 31 nm and from mostly [002] to [100] by increasing the pH from 1 to 4, respectively. Smoother coatings and higher current efficiencies were obtained by the addition of 1 g/L sodium dodecyl sulfate (SDS) to the bath. Highest hardness of the nano-crystalline and the amorphous coatings was about 600 and 750 HV, which increased and reached 760 and 1090 HV after heat treatment, respectively.

Graphite fluoride as a solid lubricant in a polyimide binder

NASA Technical Reports Server (NTRS)

Fusaro, R. L.; Sliney, H. E.

1972-01-01

Polyimide resin (PI) was shown to be a suitable binder material for the solid lubricant graphite fluoride, (CF(1.1))n. Comparisons were made to similar tests using PI-bonded MOS2 films, graphite fluoride rubbed films, and MOS2 rubbed films. The results showed that, at any one specific temperature between 25 and 400 C, the wear life of PI-bonded graphite fluoride films exceeded those of the other three films by at least a factor of 2 and by as much as a factor of 60. Minimum friction coefficients for the PI-bonded films were 0.08 for graphite fluoride and 0.04 for MOS2. The rider wear rates for the two PI-bonded films at 25 C were nearly equal.

Film thickness for different regimes of fluid-film lubrication

NASA Technical Reports Server (NTRS)

Hamrock, B. J.

1980-01-01

Film thickness equations are provided for four fluid-film lubrication regimes found in elliptical contacts. These regimes are isoviscous-rigid; viscous-rigid; elastohydrodynamic lubrication of low-elastic-modulus materials (soft EHL), or isoviscous-elastic; and elastohydrodynamic lubrication of high-elastic-modulus materials (hard EHL), or viscous-elastic. The influence or lack of influence of elastic and viscous effects is the factor that distinguishes these regimes. The results are presented as a map of the lubrication regimes, with film thickness contours on a log-log grid of the viscosity and elasticity for three values of the ellipticity parameter.

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.

Analysis of fluid film lubrication in artificial hip joint replacements with surfaces of high elastic modulus.

PubMed

Jin, Z M; Dowson, D; Fisher, J

1997-01-01

Lubrication mechanisms and contact mechanics have been analysed for total hip joint replacements made from hard bearing surfaces such as metal-on-metal and ceramic-on-ceramic. A similar analysis for ultra-high molecular weight polyethylene (UHMWPE) against a hard bearing surface has also been carried out and used as a reference. The most important factor influencing the predicted lubrication film thickness has been found to be the radial clearance between the ball and the socket. Full fluid film lubrication may be achieved in these hard/hard bearings provided that the surface finish of the bearing surface and the radial clearance are chosen correctly and maintained. Furthermore, there is a close relation between the predicted contact half width and the predicted lubrication film thickness. Therefore, it is important to analyse the contact mechanics in artificial hip joint replacements. Practical considerations of manufacturing these bearing surfaces have also been discussed.

Mechanics of a gaseous film barrier to lubricant wetting of elastohydrodynamically lubricated conjunctions

NASA Technical Reports Server (NTRS)

Prahl, J. M.; Hamrock, B. J.

1985-01-01

Two analytical models, one based on simple hydrodynamic lubrication and the other on soft elastohydrodynamic lubrication, are presented and compared to delineate the dominant physical parameters that govern the mechanics of a gaseous film between a small droplet of lubricant and the outer race of a ball bearing. Both models are based on the balance of gravity forces, air drag forces, and air film lubrication forces and incorporate a drag coefficient C sub D and a lubrication coefficient C sub L to be determined from experiment. The soft elastohydrodynamic lubrication (EHL) model considers the effects of droplet deformation and solid-surface geometry; the simpler hydrodynamic lubrication (HL) model assumes that the droplet remains essentially spherical. The droplet's angular position depended primarily on the ratio of gas inertia to droplet gravity forces and on the gas Reynolds number and weakly on the ratio of droplet gravity forces to surface tension forces (Bond number) and geometric ratios for the soft EHL. An experimental configuration in which an oil droplet is supported by an air film on the rotating outer race of a ball bearing within a pressure-controlled chamber produced measurements of droplet angular position as a function of outer-race velocity droplet size and type, and chamber pressure.

Development of Dry Lubricated Harmonic Drives for Space Applications ('HarmLES')

NASA Astrophysics Data System (ADS)

Jansson, Markus; Koenen, Hans; Viviente, Jose-Luis; Tvaruzka, Adam; Merstallinger, Andreas

2013-09-01

Today, Harmonic Drive® gears are used in several space flight mechanisms as they provide advantages like zero backlash, a high gear stiffness and a high transmission accuracy. In most cases those gears are used in grease lubricated condition, whereas this is always linked to the risk of outgassing and limits significantly the operational temperature.In order to increase the temperature range, trials to apply solid lubricants to Harmonic Drive® gears, as commonly used for e. g. bearings, were performed. Based on these trials it was found that the gears can be operated even at -269°C. Anyhow, although being used in various cryogenic applications, the reachable lifetime is comparably short. Hence the EU - funded project harmLES was started in 2011 in order to increase the accessible lifetime by developing a new Harmonic Drive® gear type. This activity is based on an integrated approach covering gear design, materials and coating.

Solid Lubricants for Space Structures

DTIC Science & Technology

1993-04-17

will utilize mechanically interlocked hardware (caged bearings or bearings for ultra precision gimbals pointing mechanisms) controlled through precision...structure unless the lubricant were of low vapor pressure and/or suitably sealed to I prevent molecular effusion . While temperatures within spacecraft or...incorporation in the continuous cast system. The die made of graphite, consists of a plurality of openings or holes located in the die and positioned (unlined

Role of adsorption in liquid lubrication

NASA Technical Reports Server (NTRS)

Groszek, A. J.

1973-01-01

Changes at solid-liquid interfaces caused by adsorption from solution are discussed paying attention to the following aspects: (1) stability of adsorbed films and the structure of metal-additive-film-liquid interface and effect of adsorbate orientation. (2) chemical versus physical adsorption, (3) heat of adsorption, (4) adsorption of additives, (5) activated adsorption, effect of activating adsorbates, (6) displacement phenomena at solid-liquid interfaces, (7) competition of antiwear additives, their solvents, and water, (8) effect of adsorption on the orientation of liquid in the interfacial region, and (9) relation between the chemical nature of solid surfaces and their interaction with liquid lubricants. The relevance of the above adsorption phenomena to lubrication is discussed, referring where possible to specific examples.

CVD Diamond, DLC, and c-BN Coatings for Solid Film Lubrication

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1998-01-01

When the main criteria for judging coating performance were coefficient of friction and wear rate, which had to be less than 0.1 and 10(exp -6) mm(exp 3)/N-m, respectively, carbon- and nitrogen-ion-implanted, fine-grain CVD diamond and DLC ion beam deposited on fine-grain CVD diamond met the requirements regardless of environment (vacuum, nitrogen, and air).

Experimental investigations on the effect of process parameters with the use of minimum quantity solid lubrication in turning

NASA Astrophysics Data System (ADS)

Makhesana, Mayur A.; Patel, K. M.; Mawandiya, B. K.

2018-04-01

Turning process is a very basic process in any field of mechanical application. During turning process, most of the energy is converted into heat because of the friction between work piece and tool. Heat generation can affect the surface quality of the work piece and tool life. To reduce the heat generation, Conventional Lubrication process is used in most of the industry. Minimum quantity lubrication has been an effective alternative to improve the performance of machining process. In this present work, effort has been made to study the effect of various process parameters on the surface roughness and power consumption during turning of EN8 steel material. Result revealed the effect of depth of cut and feed on the obtained surface roughness value. Further the effect of solid lubricant has been also studied and optimization of process parameters is also done for the turning process.

A Preliminary Study on the Vapor/Mist Phase Lubrication of a Spur Gearbox

NASA Technical Reports Server (NTRS)

Morales, Wilfredo; Handschuh, Robert F.

1999-01-01

Organophosphates have been the primary compounds used in vapor/mist phase lubrication studies involving ferrous bearing material. Experimental results have indicated that the initial formation of an iron phosphate film on a rubbing ferrous surface, followed by the growth (by cationic diffusion) of a lubricious pyrophosphate-type coating over the iron phosphate, is the reason organophosphates work well as vapor/mist phase lubricants. Recent work, however, has shown that this mechanism leads to the depletion of surface iron atoms and to eventual lubrication failure. A new organophosphate formulation was developed which circumvents surface iron depletion. This formulation was tested by generating an iron phosphate coating on an aluminum surface. The new formulation was then used to vapor/mist phase lubricate a spur gearbox in a preliminary study.

CVD Diamond, DLC, and c-BN Coatings for Solid Film Lubrication

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa; Murakawa, Masao; Watanabe, Shuichi; Takeuchi, Sadao; Miyake, Shojiro; Wu, Richard L. C.

1998-01-01

The main criteria for judging coating performance were coefficient of friction and wear rate, which had to be less than 0.1 and 10(exp -6) cubic MM /(N*m), respectively. Carbon- and nitrogen-ion-implanted, fine-grain, chemical-vapor-deposited (CVD) diamond and diamondlike carbon (DLC) ion beam deposited on fine-grain CVD diamond met the criteria regardless of environment (vacuum, nitrogen, and air).

Surface Morphology and Hardness Analysis of TiCN Coated AA7075 Aluminium Alloy

NASA Astrophysics Data System (ADS)

Srinath, M. K.; Ganesha Prasad, M. S.

2017-12-01

Successful titanium carbonitride (TiCN) coating on AA7075 plates using the PVD technique depends upon many variables, including temperature, pressure, incident angle and energy of the reactive ions. Coated specimens have shown an increase in their surface hardness of 2.566 GPa. In this work, an attempt to further augment the surface hardness and understand its effects on the surface morphology was performed through heat treatments at 500°C for different duration of times. Specimen's heat treated at 500°C for 1 h exhibited a maximum surface hardness of 6.433 GPa, corresponding to an increase of 92.07%. The XRD results showed the presence of Al2Ti and AlTi3N and indicate the bond created between them. Unit cell lattice parameters in the XRD data are calculated using Bragg's law. The SEM images exhibit increasing crack sizes as the heat treatment time is increased. From the studies, the heat treatment duration can be optimized to 1 h, which exhibited an augmented surface hardness, as further increases in durations caused a drop in the surface hardness. The heat treatment effectively modified the surface hardness. Equations providing the relationships that temperature and time have with the reaction parameters are presented.

Mechanical strength and thermophysical properties of PM212: A high temperature self-lubricating powder metallurgy composite

NASA Technical Reports Server (NTRS)

Edwards, Phillip M.; Sliney, Harold E.; Dellacorte, Christopher; Whittenberger, J. Daniel; Martineau, Robert R.

1990-01-01

A powder metallurgy composite, PM212, composed of metal bonded chromium carbide and solid lubricants is shown to be self-lubricating to a maximum application temperature of 900 C. The high temperature compressive strength, tensile strength, thermal expansion and thermal conductivity data needed to design PM212 sliding contact bearings and seals are reported for sintered and isostatically pressed (HIPed) versions of PM212. Other properties presented are room temperature density, hardness, and elastic modulus. In general, both versions appear to have adequate strength to be considered as sliding contact bearing materials, but the HIPed version, which is fully dense, is much stronger than the sintered version which contains about 20 percent pore volume. The sintered material is less costly to make, but the HIPed version is better where high compressive strength is important.

Influence of lubrication forces in direct numerical simulations of particle-laden flows

NASA Astrophysics Data System (ADS)

Maitri, Rohit; Peters, Frank; Padding, Johan; Kuipers, Hans

2016-11-01

Accurate numerical representation of particle-laden flows is important for fundamental understanding and optimizing the complex processes such as proppant transport in fracking. Liquid-solid flows are fundamentally different from gas-solid flows because of lower density ratios (solid to fluid) and non-negligible lubrication forces. In this interface resolved model, fluid-solid coupling is achieved by incorporating the no-slip boundary condition implicitly at particle's surfaces by means of an efficient second order ghost-cell immersed boundary method. A fixed Eulerian grid is used for solving the Navier-Stokes equations and the particle-particle interactions are implemented using the soft sphere collision and sub-grid scale lubrication model. Due to the range of influence of lubrication force on a smaller scale than the grid size, it is important to implement the lubrication model accurately. In this work, different implementations of the lubrication model on particle dynamics are studied for various flow conditions. The effect of a particle surface roughness on lubrication force and the particle transport is also investigated. This study is aimed at developing a validated methodology to incorporate lubrication models in direct numerical simulation of particle laden flows. This research is supported from Grant 13CSER014 of the Foundation for Fundamental Research on Matter (FOM), which is part of the Netherlands Organisation for Scientific Research (NWO).

Solid Lubricated Rolling Element Bearings

DTIC Science & Technology

1979-02-15

lubricant into uneven patches of varnish . This varnish , along with the file-like action of the exposed ball carbides on the relatively softer races, can...its structure. Fluorine , one of the most reactive elements, reacts with graphite without combustion from about 790’F to 1022°F, forming a grey-colored...to allow for molding and machining after molding. 0 Method 2 (Hughes) Impregnating these dense weaves with a Thermid 600 polyimide varnish

Effect of heat treatment duration on tribological behavior of electroless Ni-(high)P coatings

NASA Astrophysics Data System (ADS)

Biswas, A.; Das, S. K.; Sahoo, P.

2016-09-01

Electroless nickel coating occurs through an autocatalytic chemical reaction and without the aid of electricity. From tribological perspective, it is recommended due to its high hardness, wear resistance, lubricity and corrosion resistance properties. In this paper electroless Ni-P coatings with high phosphorous weight percentages are developed on mild steel (AISI 1040) substrates. The coatings are subjected to heat treatment at 300°C and 500°C for time durations up to 4 hours. The effect of heat treatment duration on the hardness as well as tribological properties is discussed in detail. Hardness is measured in a micro hardness tester while the tribological tests are carried out on a pin-on-disc tribotester. Wear is reported in the form of wear rates of the sample subjected to the test. As expected, heat treatment of electroless Ni-P coating results in enhancement in its hardness which in turn increases its wear resistance. The present study also finds that duration of heat treatment has quite an effect on the properties of the coating. Increase in heat treatment time in general results in increase in the hardness of the coating. Coefficient of friction is also found to be lesser for the samples heat treated for longer durations (4 hour). However, in case of wear, similar trend is not observed. Instead samples heat treated for 2 to 3 hour display better wear resistance compared to the same heat treated for 4 hour duration. The microstructure of the coating is also carried out to ensure about its proper development. From scanning electron microscopy (SEM), the coating is found to possess the conventional nodular structure while energy dispersive X-ray analysis (EDX) shows that the phosphorous content in the coating to be greater than 9%. This means that the current coating belongs to the high phosphorous category. From X-ray diffraction analysis (XRD), it is found that coating is amorphous in as-deposited condition but transforms into a crystalline structure with

Simulation of automotive wrist pin joint and tribological studies of tin coated Al-Si alloy, metal matrix composites and nitrogen ceramics under mixed lubrication

NASA Astrophysics Data System (ADS)

Wang, Qian

Development of automotive engines with high power output demands the application of high strength materials with good tribological properties. Metal matrix composites (MMC's) and some nitrogen ceramics are of interest to replace some conventional materials in the piston/pin/connecting rod design. A simulation study has been developed to explore the possibility to employ MMC's as bearing materials and ceramics as journal materials, and to investigate the related wear mechanisms and the possible journal bearing failure mechanisms. Conventional tin coated Al-Si alloy (Al-Si/Sn) have been studied for the base line information. A mixed lubrication model for journal bearing with a soft coating has been developed and applied to the contact and temperature analysis of the Al-Si/Sn bearing. Experimental studies were performed to reveal the bearing friction and wear behavior. Tin coating exhibited great a advantage in friction reduction, however, it suffered significant wear through pitting and debonding. When the tin wore out, the Al-Si/steel contact experienced higher friction. A cast and P/M MMC's in the lubricated contact with case hardened steel and ceramic journals were studied experimentally. Without sufficient material removal in the conformal contact situation, MMC bearings in the MMC/steel pairs gained weight due to iron transfer and surface tribochemical reactions with the lubricant additives and contact failure occurred. However, the MMC/ceramic contacts demonstrated promising tribological behavior with low friction and high wear resistance, and should be considered for new journal bearing design. Ceramics are wear resistant. Ceramic surface roughness is very crucial when the journals are in contact with the tin coated bearings. In contact with MMC bearings, ceramic surface quality and fracture toughness seem to play some important roles in affecting the friction coefficient. The wear of silicon nitride and beta sialon (A) journals is pitting due to grain

Solid coatings deposited from liquid methyl methacrylate via Plasma Polymerization

NASA Astrophysics Data System (ADS)

Wurlitzer, Lisa; Maus-Friedrichs, Wolfgang; Dahle, Sebastian

2016-09-01

The polymerization of methyl methacrylate via plasma discharges is well known today. Usually, plasma-enhanced chemical vapor deposition (PECVD) is used to deposit polymer coatings. Solid coatings are formed out of the liquid phase from methyl methacrylate via dielectric barrier discharge. The formation of the coating proceeds in the gas and the liquid phase. To learn more about the reactions in the two phases, the coatings from MMA monomer will be compared to those from MMA resin. Finally, attenuated total reflection infrared spectroscopy, confocal laser scanning microscopy and X-ray photoelectron spectroscopy are employed to characterize the solid coatings. In conclusion, the plasma enhanced chemical solution deposition is compared to the classical thermal polymerization of MMA.

Effects of friction layer characteristics on the tribological properties of Ni3Al solid-lubricating composites at different load conditions

NASA Astrophysics Data System (ADS)

Lu, Guanchen; Shi, Xiaoliang; Huang, Yuchun; Liu, Xiyao; Yang, Meijun

2018-05-01

This paper investigates the effects of friction layer characteristics of Ni3Al matrix self-lubricating composites (NMCs) on the tribological properties sliding against ceramic ball Si3N4 at dry friction process at the different load conditions. The characteristics of friction layer are performed in terms of hardness of wear scars, thickness and elemental distributions of friction layer. The results show that the microhardness of wear scars of NMCs increases with the increase of the sliding time and applied load, which results in friction coefficient reduced and wear rate decreased, indicating that the tribological performance of NMCs is obviously affected by microhardness of wear scar. However, under excessive applied load, the performance of friction layer of NMCs is deteriorated for the spalling of wear debris and deformation of contact surface. Therefore, selecting appropriate load conditions during the sliding contact, at the transition to the optimal properties of friction layer maybe occur. NMCs exhibits excellent tribological properties at 15N, which leads to the lowest friction coefficient (0.386) and wear rate (2.48 × 10‑5 mm3 N‑1 m‑1), as well as the smoothest surface of wear track compared with the other load conditions. Meanwhile, the elemental distributions analysis of cross-section of friction layer of NMCs shows that the frictional structures can be divided into three main layers. The thickness of the friction-affected layer varies with the changing of applied load. These results could provide a reference for preparing the solid-lubrication materials with better tribological properties.

Porous Organic Nanolayers for Coating of Solid-state Devices

PubMed Central

2011-01-01

Background Highly hydrophobic surfaces can have very low surface energy and such low surface energy biological interfaces can be obtained using fluorinated coatings on surfaces. Deposition of biocompatible organic films on solid-state surfaces is attained with techniques like plasma polymerization, biomineralization and chemical vapor deposition. All these require special equipment or harsh chemicals. This paper presents a simple vapor-phase approach to directly coat solid-state surfaces with biocompatible films without any harsh chemical or plasma treatment. Hydrophilic and hydrophobic monomers were used for reaction and deposition of nanolayer films. The monomers were characterized and showed a very consistent coating of 3D micropore structures. Results The coating showed nano-textured surface morphology which can aid cell growth and provide rich molecular functionalization. The surface properties of the obtained film were regulated by varying monomer concentrations, reaction time and the vacuum pressure in a simple reaction chamber. Films were characterized by contact angle analysis for surface energy and with profilometer to measure the thickness. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed the chemical composition of the coated films. Variations in the FTIR results with respect to different concentrations of monomers showed the chemical composition of the resulting films. Conclusion The presented approach of vapor-phase coating of solid-state structures is important and applicable in many areas of bio-nano interface development. The exposure of coatings to the solutions of different pH showed the stability of the coatings in chemical surroundings. The organic nanocoating of films can be used in bio-implants and many medical devices. PMID:21569579

Excellent lubricating behavior of Brasenia schreberi mucilage.

PubMed

Li, Jinjin; Liu, Yuhong; Luo, Jianbin; Liu, Pengxiao; Zhang, Chenhui

2012-05-22

The present work reports an excellent lubrication property of an aquatic plant called Brasenia schreberi (BS). To investigate the lubrication characteristics of the BS mucilage, a novel measuring system is designed, and an ultralow friction coefficient about 0.005 between the mucilage and glass surface has been obtained. It is found that the ultralow friction is closely related to the structure of mucilage and water molecules in the mucilage. The microstructure analysis indicates that the mucilage surrounding BS forms a kind of polysaccharide gel with many nanosheets. A possible lubrication mechanism is proposed that the formation of hydration layers among these polymer nanosheets with plenty of bonded water molecules causes the ultralow friction. The excellent lubrication property has a potential application for reducing the friction between a glossy pill coated with such layer of mucilage and people's throats.

Friction, Wear, and Evaporation Rates of Various Materials in Vacuum to 10(exp -7) mm Hg

NASA Technical Reports Server (NTRS)

Buckley, Donald H.; Swikert, Max; Johnson, Robert L.

1961-01-01

The requirements for bearings and seals to operate in the environment of space dictate a new area for lubrication research. The low ambient pressures encountered in space can be expected to influence the behavior of oil, grease, and solid-film lubricants. The property of these materials most significantly affected by low ambient pressures is the evaporation rate. Various investigators have therefore measured the evaporation rates of oils and greases in vacuum as one method of establishing their relative merit for space applications (1-3). The results of this work have given some indication as to the oils and greases with the greatest stability at reduced ambient pressures. Only limited experimental work, however, has been reported in the literature for inorganic solids and soft metals which have potential use as solid lubricant films or coatings for hard alloy substrates [e.g. Reference ( 4 )]. In general, the evaporation rates of these materials would be lower than those of oils and greases. These films might therefore be very attractive as lubricants for high vacuum service.

Quantitative Analysis of Electroplated Nickel Coating on Hard Metal

PubMed Central

Wahab, Hassan A.; Noordin, M. Y.; Izman, S.

2013-01-01

Electroplated nickel coating on cemented carbide is a potential pretreatment technique for providing an interlayer prior to diamond deposition on the hard metal substrate. The electroplated nickel coating is expected to be of high quality, for example, indicated by having adequate thickness and uniformity. Electroplating parameters should be set accordingly for this purpose. In this study, the gap distances between the electrodes and duration of electroplating process are the investigated variables. Their effect on the coating thickness and uniformity was analyzed and quantified using design of experiment. The nickel deposition was carried out by electroplating in a standard Watt's solution keeping other plating parameters (current: 0.1 Amp, electric potential: 1.0 V, and pH: 3.5) constant. The gap distance between anode and cathode varied at 5, 10, and 15 mm, while the plating time was 10, 20, and 30 minutes. Coating thickness was found to be proportional to the plating time and inversely proportional to the electrode gap distance, while the uniformity tends to improve at a large electrode gap. Empirical models of both coating thickness and uniformity were developed within the ranges of the gap distance and plating time settings, and an optimized solution was determined using these models. PMID:23997678

Robot based deposition of WC-Co HVOF coatings on HSS cutting tools as a substitution for solid cemented carbide cutting tools

NASA Astrophysics Data System (ADS)

Tillmann, W.; Schaak, C.; Biermann, D.; Aßmuth, R.; Goeke, S.

2017-03-01

Cemented carbide (hard metal) cutting tools are the first choice to machine hard materials or to conduct high performance cutting processes. Main advantages of cemented carbide cutting tools are their high wear resistance (hardness) and good high temperature strength. In contrast, cemented carbide cutting tools are characterized by a low toughness and generate higher production costs, especially due to limited resources. Usually, cemented carbide cutting tools are produced by means of powder metallurgical processes. Compared to conventional manufacturing routes, these processes are more expensive and only a limited number of geometries can be realized. Furthermore, post-processing and preparing the cutting edges in order to achieve high performance tools is often required. In the present paper, an alternative method to substitute solid cemented carbide cutting tools is presented. Cutting tools made of conventional high speed steels (HSS) were coated with thick WC-Co (88/12) layers by means of thermal spraying (HVOF). The challenge is to obtain a dense, homogenous, and near-net-shape coating on the flanks and the cutting edge. For this purpose, different coating strategies were realized using an industrial robot. The coating properties were subsequently investigated. After this initial step, the surfaces of the cutting tools were ground and selected cutting edges were prepared by means of wet abrasive jet machining to achieve a smooth and round micro shape. Machining tests were conducted with these coated, ground and prepared cutting tools. The occurring wear phenomena were analyzed and compared to conventional HSS cutting tools. Overall, the results of the experiments proved that the coating withstands mechanical stresses during machining. In the conducted experiments, the coated cutting tools showed less wear than conventional HSS cutting tools. With respect to the initial wear resistance, additional benefits can be obtained by preparing the cutting edge by means

HarmLES- Development of Dry Lubricated Harmonic Drives® Gears for Space Applications

NASA Astrophysics Data System (ADS)

Jansson, Markus; Koenen, Hans; Brizuela, Marta; Vivente, Jose-Luis; Merstallinger, Andreas

2015-09-01

Harmonic Drive® gears are used in several space flight mechanisms such as SADM’s or pointing mechanisms. Main reasons for choosing the gears are advantages like zero backlash, high gear stiffness and high transmission accuracy. Nowadays typically grease lubrication is used, whereas this is linked to the risk of outgassing and limits the operational temperature.In order to increase the temperature range, trials to apply solid lubricants to Harmonic Drive® gears, were performed. Based on these trials it was found that the gears can be operated even at -269°C. Anyhow, although being used in various cryogenic applications, the reachable lifetime is comparably short. So as to improve the achievable endurance an essential development was necessary. Hence the EU - funded project HarmLES was executed in order to significantly increase the accessible lifetime. Following an integrated approach covering gear design, materials and coating, the prototype of a new Harmonic Drive® gear type was developed.

Oleoplaning droplets on lubricated surfaces

NASA Astrophysics Data System (ADS)

Daniel, Dan; Timonen, Jaakko V. I.; Li, Ruoping; Velling, Seneca J.; Aizenberg, Joanna

2017-10-01

Recently, there has been much interest in using lubricated surfaces to achieve extreme liquid repellency: a foreign droplet immiscible with the underlying lubricant layer was shown to slide off at a small tilt angle <5°. This behaviour was hypothesized to arise from a thin lubricant overlayer film sandwiched between the droplet and solid substrate, but this has not been observed experimentally. Here, using thin-film interference, we are able to visualize the intercalated film under both static and dynamic conditions. We further demonstrate that for a moving droplet, the film thickness follows the Landau-Levich-Derjaguin law. The droplet is therefore oleoplaning--akin to tyres hydroplaning on a wet road--with minimal dissipative force and no contact line pinning. The techniques and insights presented in this study will inform future work on the fundamentals of wetting for lubricated surfaces and enable their rational design.

Optimization and testing of solid thin film lubrication deposition processes

NASA Astrophysics Data System (ADS)

Danyluk, Michael J.

A novel method for testing solid thin films in rolling contact fatigue (RCF) under ultra-high vacuum (UHV) and high rotational speeds (130 Hz) is presented in this thesis. The UHV-RCF platform is used to quantify the adhesion and lubrication aspects of two thin film coatings deposited on ball-bearings using a physical vapor deposition ion plating process. Plasma properties during ion plating were measured using a Langmuir probe and there is a connection between ion flux, film stress, film adhesion, process voltage, pressure, and RCF life. The UHV-RCF platform and vacuum chamber were constructed using off-the-shelf components and 88 RCF tests in high vacuum have been completed. Maximum RCF life was achieved by maintaining an ion flux between 10 13 to 1015 (cm-2 s-1) with a process voltage and pressure near 1.5 kV and 15 mTorr. Two controller schemes were investigated to maintain optimal plasma conditions for maximum RCF life: PID and LQR. Pressure disturbances to the plasma have a detrimental effect on RCF life. Control algorithms that mitigate pressure and voltage disturbances already exist. However, feedback from the plasma to detect disturbances has not been explored related to deposition processes in the thin-film science literature. Manometer based pressure monitoring systems have a 1 to 2 second delay time and are too slow to detect common pressure bursts during the deposition process. Plasma diagnostic feedback is much faster, of the order of 0.1 second. Plasma total-current feedback was used successfully to detect a typical pressure disturbance associated with the ion plating process. Plasma current is related to ion density and process pressure. A real-time control application was used to detect the pressure disturbance by monitoring plasma-total current and converting it to feedback-input to a pressure control system. Pressure overshoot was eliminated using a nominal PID controller with feedback from a plasma-current diagnostic measurement tool.

Improved Friction and Wear of M50 Steel Composites Incorporated with ZnO as a Solid Lubricant with Different Concentrations Under Different Loads

NASA Astrophysics Data System (ADS)

Essa, F. A.; Zhang, Qiaoxin; Huang, Xingjiu; Ibrahim, Ahmed Mohamed Mahmoud; Ali, Mohamed Kamal Ahmed; Abdelkareem, Mohamed A. A.; Elagouz, Ahmed

2017-10-01

This experimental study explores improving the tribological behavior of M50 steel using ZnO as a solid lubricant with different concentrations of 5, 10, 15, 20, and 25 wt.%. Tribological tests were conducted using pin-on-disk tribometer under different loads of 3, 6, 9, and 12 N and constant sliding speed of 0.2 m s-1 in air. XRD, EPMA, FESEM, EDS mapping, and XPS tests were performed to understand the major mechanisms leading to improve the tribological and mechanical properties of M50 composites. Results showed that the best tribological and mechanical properties were obtained at 20.0 wt.% of ZnO. Friction coefficient and wear rate were reduced by 52.909 and 70%, respectively, due to the formation of tribo-films on the worn surfaces. Furthermore, the hardness of M50 composites increased by 27.86%. Our study provides results with suggestions to overcome the challenges facing the technology when using M50 matrix composites in mechanical applications.

Hydrodynamic air lubricated compliant surface bearing for an automotive gas turbine engine. 2: Materials and coatings

NASA Technical Reports Server (NTRS)

Bhushan, B.; Ruscitto, D.; Gray, S.

1978-01-01

Material coatings for an air-lubricated, compliant journal bearing for an automotive gas turbine engine were exposed to service test temperatures of 540 C or 650 C for 300 hours, and to 10 temperature cycles from room temperatures to the service test temperatures. Selected coatings were then put on journal and partial-arc foils and tested in start-stop cycle tests at 14 kPa (2 psi) loading for 2000 cycles. Half of the test cycles were performed at a test chamber service temperature of 540 C (1000 F) or 650 C (1200 F); the other half were performed at room temperature. Based on test results, the following combinations and their service temperature limitations are recommended: HL-800 TM (CdO and graphite) on foil versus chrome carbide on journal up to 370 C (700 F); NASA PS 120 (Tribaloy 400, silver and CaF2 on journal versus uncoated foil up to 540 C (1000 F); and Kaman DES on journal and foil up to 640 C (1200 F). Kaman DES coating system was further tested successfully at 35 kPa (5 psi) loading for 2000 start-stop cycles.

Lubricant reflow after laser heating in heat assisted magnetic recording

NASA Astrophysics Data System (ADS)

Wu, Haoyu; Mendez, Alejandro Rodriguez; Xiong, Shaomin; Bogy, David B.

2015-05-01

In heat assisted magnetic recording (HAMR) technology for hard disk drives, the media will be heated to about 500 °C during the writing process in order to reduce its magnetic coercivity and thus allow data writing with the magnetic head transducers. The traditional lubricants such as Z-dol and Z-tetraol may not be able to perform in such harsh heating conditions due to evaporation, decomposition and thermal depletion. However, some of the lubricant depletion can be recovered due to reflow after a period of time, which can help to reduce the chance of head disk interface failure. In this study, experiments of lubricant thermal depletion and reflow were performed using a HAMR test stage for a Z-tetraol type lubricant. Various lubricant depletion profiles were generated using different laser heating conditions. The lubricant reflow process after thermal depletion was monitored by use of an optical surface analyzer. In addition, a continuum based lubrication model was developed to simulate the lubricant reflow process. Reasonably good agreement between simulations and experiments was achieved.

Using Hysteretic Energy to Evaluate Damping Characteristics of Hard Coating on Titanium

DTIC Science & Technology

2013-03-21

Ivancic, Frank T. The Effect of a Hard Coating on the Damping and Fatigue Life of Titanium. Air Force Institute of Technology (AU), Wright-Patterson AFB... aluminum specimens to determine the effects of losses for different grip mechanisms, a suspected problem in previous work with this method. Peak...done in a vacuum, and the nature of the free-decay test also confines strain to relatively low values for coated specimens (< 1000 µε) (Reed 2007

An Evaluation of Liquid, Solid, and Grease Lubricants for Space Mechanisms Using a Spiral Orbit Tribometer

NASA Technical Reports Server (NTRS)

Buttery, Michael

2010-01-01

We present the findings of the test program performed by The European Space Tribology Laboratory (ESTL) to evaluate the performance (friction and lifetime) of a number of space lubricants under vacuum using a Spiral Orbit Tribometer (SOT). Focus was given to a comparison of various popular space oils, a comparison study between the old and new MAPLUB grease formulations, and the performance of commonly used solid lubricants under various conditions. Tests demonstrated that the lifetimes of hydrocarbon NYE oils 2001 & 2001A outperformed those of the perfluroropolyalkylether (PFPE) oils Fomblin Z25 & Z60, though these pairs displayed similar behavior. This relationship was also generally seen for greases; with the lifetimes of the multiple alkylated cyclopentane (MAC)-based greases being extended in comparison to the PFPE-based greases. Testing on greases also demonstrated similar performance between the old (-a) and new (-b) formulations when considering PFPE-based MAPLUB greases, and indeed for all tested PFPE-based non-MAPLUB greases, but significantly shorter lifetimes for the new formulations when considering MAC-based MAPLUB greases. MAPLUB MAC greases containing molybdenum disulphide (MoS2) thickener were also found to display reduced lifetimes. For solid lubricants, lead displayed significantly extended lifetimes over MoS2, speculated to be caused by redistribution of lead from the ball onto all contact surfaces during the test. Friction coefficients were seen to be some 2.5x higher for lead than for MoS2 under similar conditions, a result that corresponds well with conventional bearing tests. The work described was performed under contract for the European Space Agency as part of the Tribology Applications Program, with all funding for testing and apparatus provided by European Space Agency (ESA).

Pretreatment of lubricated surfaces with sputtered cadmium oxide

NASA Technical Reports Server (NTRS)

Fusaro, Robert L. (Inventor)

1991-01-01

Cadmium oxide is used with a dry solid lubricant on a surface to improve wear resistance. The surface topography is first altered by photochemical etching to a predetermined pattern. The cadmium oxide is then sputtered onto the altered surface to form an intermediate layer to more tightly hold the dry lubricant, such as graphite.

Hard ceramic coatings: an experimental study on a novel damping treatment

NASA Astrophysics Data System (ADS)

Patsias, Sophoclis; Tassini, Nicola; Stanway, Roger

2004-07-01

This paper describes a novel damping treatment, namely hard ceramic coatings. These materials can be applied on almost any surface (internal or external) of a component. Their effect is the significant reduction of vibration levels and hence the extension of life expectancy of the component. The damping features of air-plasma-sprayed ceramic coatings (for example amplitude dependence, influence of initial amplitude) are discussed and the experimental procedure employed for testing and characterising such materials is also described. This test procedure is based around a custom-developed rig that allows one to measure the damping (internal friction) of specimens at controlled frequencies, strain amplitudes and, if required, various temperatures. A commonly used Thermal Barrier Coating, Yttria Stabilised Zirconia (8%), is used to demonstrate the above mentioned features. The damping effectiveness of this coating is then compared against two established damping treatments: polymer Free Layer Damping (FLD) and Constrained Layer Damping (CLD). The paper discusses the major issues in characterising ceramic damping coatings and their damping effectiveness when compared against the "traditional" approaches. Finally, the paper concludes with suggestions for further research.

The effect of annealing on structure and hardness of (Fe-Cr)-50 at.% Al coatings synthesized by mechanical alloying

NASA Astrophysics Data System (ADS)

Ciswandi, Aryanto, Didik; Irmaniar, Tjahjono, Arif; Sudiro, Toto

2018-05-01

In this research, the deposition of (Fe-Cr)-50at.% Al coatings on low carbon steel was carried out by a mechanical alloying (MA) technique. The MA was performed in a shaker mill for 4 hours. Two types of Fe-Cr powders as starting material were used, high purity Fe-Cr powders: (Fe-12.5Cr)-50Al and (Fe-25Cr)-50Al, and Fe-Cr lump powder: (50FeCr)-50Al (in at.%). The coated samples were then annealed in a vacuum furnace at 700°C for 1h. The characterizations of coating structure before and after annealing were studied by XRD and SEM-EDX, while the coating hardness was measured by micro-Vickers hardness tester. Before annealing, all of coating composition were composed mainly of (Fe,Cr)Al phase. After annealing, the FeAl and Fe0.99Cr0.02Al0.99 intermetallic phases was formed in the (Fe-12.5Cr)-50Al and (Fe-25Cr)-50Al coatings. In addition, Fe2CrAlwas also found in the (Fe-25Cr)-50Al coating. Whilethe AlCr2 intermetallic phase was detected as the main phase of (50FeCr)-50Al coating. The cross-sectional microstructure showed that the (Fe-12.5Cr)-50Al and (Fe-25Cr)-50Al coatings have a smoother structure compared to (50FeCr)-50Al coating. The annealing led to intermetallic phase formation and an increasing coating hardness.

Microscopic aspects of the effect of friction reducers at the lubrication limit. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Mansot, J. L.

1984-01-01

An attempt is made to analytically model the physicochemical properties of lubricants and their capacity to reduce friction. A technique of frozen fracturing of the lubricants was employed to study the dispersion of additives throughout a lubricant. Adsorption was observed at the liquid-solid interface, which was the region where the solid and lubricant met, and the molecular dispersion of the additive enhanced the effectiveness of the lubricant. The electrically conductive characteristics of the lubricant at the friction interface indicated the presence of tunneling effects. The Bethe model was used to examine the relationship between the coefficient of friction and the variation of interface thickness. The electron transport permitted an inelastic tunnel electron spectroscopic investigation of the molecular transformations undergone by the additive during friction episodes.

Thermodynamic stability in elastic systems: Hard spheres embedded in a finite spherical elastic solid.

PubMed

Solano-Altamirano, J M; Goldman, Saul

2015-12-01

We determined the total system elastic Helmholtz free energy, under the constraints of constant temperature and volume, for systems comprised of one or more perfectly bonded hard spherical inclusions (i.e. "hard spheres") embedded in a finite spherical elastic solid. Dirichlet boundary conditions were applied both at the surface(s) of the hard spheres, and at the outer surface of the elastic solid. The boundary conditions at the surface of the spheres were used to describe the rigid displacements of the spheres, relative to their initial location(s) in the unstressed initial state. These displacements, together with the initial positions, provided the final shape of the strained elastic solid. The boundary conditions at the outer surface of the elastic medium were used to ensure constancy of the system volume. We determined the strain and stress tensors numerically, using a method that combines the Neuber-Papkovich spherical harmonic decomposition, the Schwartz alternating method, and Least-squares for determining the spherical harmonic expansion coefficients. The total system elastic Helmholtz free energy was determined by numerically integrating the elastic Helmholtz free energy density over the volume of the elastic solid, either by a quadrature, or a Monte Carlo method, or both. Depending on the initial position of the hard sphere(s) (or equivalently, the shape of the un-deformed stress-free elastic solid), and the displacements, either stationary or non-stationary Helmholtz free energy minima were found. The non-stationary minima, which involved the hard spheres nearly in contact with one another, corresponded to lower Helmholtz free energies, than did the stationary minima, for which the hard spheres were further away from one another.

Investigation of stand-off distance effect on structure, adhesion and hardness of copper coatings obtained by the APS technique

NASA Astrophysics Data System (ADS)

Masoumeh, Goudarzi; Shahrooz, Saviz; Mahmood, Ghoranneviss; Ahmad, Salar Elahi

2018-03-01

The outbreak of the disease and infection in the hospital environment and medical equipment is one of the concerns of modern life. One of the effective ways for preventing and reducing the complications of infections is modification of the surface. Here, the handmade atmospheric plasma spray system is used for accumulating copper as an antibacterial agent on the 316L stainless steel substrate, which applies to hospital environment and medical equipment. As a durable coating with proper adhesion is needed on the substrate, the effect of stand-off distance (SOD) which is an important parameter of the spray on the microstructure, the hardness and adhesion of the copper coating on the 316L stainless steel were investigated. The structure and phase composition of copper depositions were investigated using scanning electron microscopy and X-ray diffraction. The adhesion and hardness of depositions are evidenced using the cross cut tester and Vickers hardness tester, respectively. The findings confirm that the voids in the coatings increase with increasing SOD, which leads to decreasing the hardness of coatings and also the adhesion strength between depositions and substrate. In addition, by increasing the SOD, the oxygen content and the size of grains in the lamellae (fine structure) of coatings also increase.

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.

Effect of Substrate Bias on Friction Coefficient, Adhesion Strength and Hardness of TiN-COATED Tool Steel

NASA Astrophysics Data System (ADS)

Hamzah, Esah; Ali, Mubarak; Toff, Mohd Radzi Hj. Mohd

In the present study, TiN coatings have been deposited on D2 tool steel substrates by using cathodic arc physical vapor deposition technique. The objective of this research work is to determine the usefulness of TiN coatings in order to improve the micro-Vickers hardness and friction coefficient of TiN coating deposited on D2 tool steel, which is widely used in tooling applications. A Pin-on-Disc test was carried out to study the coefficient of friction versus sliding distance of TiN coating deposited at various substrate biases. The standard deviation parameter during tribo-test result showed that the coating deposited at substrate bias of -75 V was the most stable coating. A significant increase in micro-Vickers hardness was recorded, when substrate bias was reduced from -150 V to zero. Scratch tester was used to compare the critical loads for coatings deposited at different bias voltages and the adhesion achievable was demonstrated with relevance to the various modes, scratch macroscopic analysis, critical load, acoustic emission and penetration depth. A considerable improvement in TiN coatings was observed as a function of various substrate bias voltages.

Systematic evaluation of common lubricants for optimal use in tablet formulation.

PubMed

Paul, Shubhajit; Sun, Changquan Calvin

2018-05-30

As an essential formulation component for large-scale tablet manufacturing, the lubricant preserves tooling by reducing die-wall friction. Unfortunately, lubrication also often results in adverse effects on tablet characteristics, such as prolonged disintegration, slowed dissolution, and reduced mechanical strength. Therefore, the choice of lubricant and its optimal concentration in a tablet formulation is a critical decision in tablet formulation development to attain low die-wall friction while minimizing negative impact on other tablet properties. Three commercially available tablet lubricants, i.e., magnesium stearate, sodium stearyl fumerate, and stearic acid, were systematically investigated in both plastic and brittle matrices to elucidate their effects on reducing die-wall friction, tablet strength, tablet hardness, tablet friability, and tablet disintegration kinetics. Clear understanding of the lubrication efficiency of commonly used lubricants as well as their impact on tablet characteristics would help future tablet formulation efforts. Copyright © 2018 Elsevier B.V. All rights reserved.

Lubricant-impregnated surfaces for electrochemical applications, and devices and systems using same

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

Solomon, Brian Richmond; Chen, Xinwei; Chiang, Yet-Ming

In certain embodiments, the invention relates to an electrochemical device having a liquid lubricant impregnated surface. At least a portion of the interior surface of the electrochemical device includes a portion that includes a plurality of solid features disposed therein. The plurality of solid features define a plurality of regions therebetween. A lubricant is disposed in the plurality of regions which retain the liquid lubricant in the plurality of regions during operation of the device. An electroactive phase comes in contact with at least the portion of the interior surface. The liquid lubricant impregnated surface introduces a slip at themore » surface when the electroactive phase flows along the surface. The electroactive phase may be a yield stress fluid.« less

Experimental investigation on hard turning of AISI 4340 steel using cemented coated carbide insert

NASA Astrophysics Data System (ADS)

Pradeep Kumar, J.; Kishore, K. P.; Ranjith Kumar, M.; Saran Karthick, K. R.; Vishnu Gowtham, S.

2018-02-01

Hard turning is a developing technology that offers many potential advantages compared to grinding, which remains the standard finishing process for critical hardened surfaces. In this work, an attempt has been made to experimentally investigate hard turning of AISI 4340 steel under wet and dry condition using cemented coated carbide insert. Hardness of the workpiece material is tested using Brinell and Rockwell hardness testers. CNC LATHE and cemented coated carbide inserts of designation CNMG 120408 are used for conducting experimental trials. Significant cutting parameters like cutting speed, feed rate and depth of cut are considered as controllable input parameters and surface roughness (Ra), tool wear are considered as output response parameters. Design of experiments is carried out with the help of Taguchi’s L9 orthogonal array. Results of response parameters like surface roughness and tool wear under wet and dry condition are analysed. It is found that surface roughness and tool wear are higher under dry machining condition when compared to wet machining condition. Feed rate significantly influences the surface roughness followed by cutting speed. Depth of cut significantly influences the tool wear followed by cutting speed.

Dry coating of solid dosage forms: an overview of processes and applications.

PubMed

Foppoli, Anastasia Anna; Maroni, Alessandra; Cerea, Matteo; Zema, Lucia; Gazzaniga, Andrea

2017-12-01

Dry coating techniques enable manufacturing of coated solid dosage forms with no, or very limited, use of solvents. As a result, major drawbacks associated with both organic solvents and aqueous coating systems can be overcome, such as toxicological, environmental, and safety-related issues on the one hand as well as costly drying phases and impaired product stability on the other. The considerable advantages related to solventless coating has been prompting a strong research interest in this field of pharmaceutics. In the article, processes and applications relevant to techniques intended for dry coating are analyzed and reviewed. Based on the physical state of the coat-forming agents, liquid- and solid-based techniques are distinguished. The former include hot-melt coating and coating by photocuring, while the latter encompass press coating and powder coating. Moreover, solventless techniques, such as injection molding and three-dimensional printing by fused deposition modeling, which are not purposely conceived for coating, are also discussed in that they would open new perspectives in the manufacturing of coated-like dosage forms.

Corrosion protection of steel by thin coatings of starch-oil dry lubricants

USDA-ARS?s Scientific Manuscript database

Corrosion of materials is one of the most serious and challenging problems faced worldwide by industry. Dry lubricants reduce friction between two metal surfaces. This research investigated the inhibition of corrosive behavior a dry lubricant formulation consisting of jet-cooked corn starch and soyb...

Compatibility of refrigerants and lubricants with elastomers. Final report

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

Hamed, G.R.; Seiple, R.H.; Taikum, Orawan

1994-01-01

The information contained in this report is designed to assist the air-conditioning and refrigeration industry in the selection of suitable elastomeric gasket and seal materials that will prove useful in various refrigerant and refrigeration lubricant environments. In part I of the program the swell behavior in the test fluids has been determined using weight and in situ diameter measurements for the refrigerants and weight, diameter and thickness measurements for the lubricants. Weight and diameter measurements are repeated after 2 and 24 hours for samples removed fro the refrigerant test fluids and 24 hours after removal from the lubricants. Part IImore » of the testing program includes the evaluation of tensile strength, hardness, weight, and dimensional changes after immersion aging in refrigerant/lubricant mixtures of selected elastomer formulations at elevated temperature and pressure.« less

Ball bearing lubrication: The elastohydrodynamics of elliptical contacts

NASA Technical Reports Server (NTRS)

Hamrock, B. J.; Dowson, D.

1981-01-01

The history of ball bearings is examined, taking into account rollers and the wheel in the early civilizations, the development of early forms of rolling-element bearings in the classical civilizations, the Middle Ages, the Industrial Revolution, the emergence of the precision ball bearing, scientific studies of contact mechanics and rolling friction, and the past fifty years. An introduction to ball bearings is presented, and aspects of ball bearing mechanics are explored. Basic characteristics of lubrication are considered along with lubrication equations, the lubrication of rigid ellipsoidal solids, and elastohydrodynamic lubrication theory. Attention is given to the theoretical results for fully flooded elliptical hydrodynamic contacts, the theoretical results for starved elliptical contacts, experimental investigations, the elastohydrodynamics of elliptical contacts for materials of low elastic modulus, the film thickness for different regimes of fluid-film lubrication, and applications.

Piezoviscous effects in nonconformal contacts lubricated hydrodynamically

NASA Technical Reports Server (NTRS)

Jeng, Y. R.; Hamrock, B. J.; Brewe, D. E.

1985-01-01

The analysis is concerned with the piezoviscous-rigid regime of lubrication for the general case of elliptical contacts. In this regime several formulas of the lubricant film thickness have been proposed by Hamrock and Dowson, by Dowson et al., and more recently by Houpert. However, either they do not include the load parameter W, which has a strong effect on film thickness, or they overestimate the film thickness by using the Barus formula for pressure-viscosity characteristics. The Roelands formula was used for the pressure-viscosity relationship. The effects of the dimensionless load, speed, and materials parameters, the radius ratio, and the lubricant entrainment direction were investigated. The dimensionless load parameter was varied over a range of one order of magnitude. The dimensionless speed parameter was varied by 5.6 times the lowest value. Conditions corresponding to the use of solid materials of steel, bronze, and silicon nitride and lubricants of paraffinic and naphthenic mineral oil were considered in obtaining the exponent in the dimensionless materials parameter. The radius ratio was varied from 0.2 to 64 (a configuration approaching a line contact). Forty-one cases were used in obtaining a minimum film thickness formula. Contour plots indicate in detail the pressure developed between the contacting solids.

Piezoviscous effects in nonconformal contacts lubricated hydrodynamically

NASA Technical Reports Server (NTRS)

Jeng, Yeau-Ren; Hamrock, Bernard J.; Brewe, David E.

1987-01-01

The analysis is concerned with the piezoviscous-rigid regime of lubrication for the general case of elliptical contacts. In this regime several formulas of the lubricant film thickness have been proposed by Hamrock and Dowson, by Dowson et al., and more recently by Houpert. However, either they do not include the load parameter W, which has a strong effect on film thickness, or they overestimate the film thickness by using the Barus formula for pressure-viscosity characteristics. The Roelands formula was used for the pressure-viscosity relationship. The effects of the dimensionless load, speed, and materials parameters, the radius ratio, and the lubricant entrainment direction were investigated. The dimensionless load parameter was varied over a range of one order of magnitude. The dimensionless speed parameter was varied by 5.6 times the lowest value. Conditions corresponding to the use of solid materials of steel, bronze, and silicon nitride and lubricants of paraffinic and naphthenic mineral oil were considered in obtaining the exponent in the dimensionless materials parameter. The radius ratio was varied from 0.2 to 64 (a configuration approaching a line contact). Forty-one cases were used in obtaining a minimum film thickness formula. Contour plots indicate in detail the pressure developed between the contacting solids.

Very Hard Corrosion-Resistant Roll-Bonded Cr Coating on Mild Steel in Presence of Graphite

NASA Astrophysics Data System (ADS)

Kumar, Pankaj; Khara, S.; Shekhar, S.; Mondal, K.

2017-12-01

The present work discusses the development of very hard Cr and Cr-carbide coating by roll bonding of Cr powder on a mild steel followed by annealing at 800, 1000, 1100 and 1200 °C with and without the presence of graphite powder packing in argon environment. In addition, the effect of a roll skin pass of 5% prior to the application of coating was studied. The presence of graphite allows diffusion of both carbon and Cr in the mild steel substrate, leading to the formation of Cr-carbide on the outer surface, making the surface very hard (VHN 1800). Depending on the annealing temperature and processing condition, diffusion layer thickness of Cr is found to be in the range of 10-250 μm with Cr content of 12.5-15 wt.% across the diffusion layer. Excellent stable passivity of the coated surface is observed in 0.2 N H2SO4, which is comparable to a highly passivating 304 stainless steel, and very low corrosion rate of the coating is observed as compared to the substrate mild steel.

Structures and Mechanical Properties of Natural and Synthetic Diamonds. Chapter 8

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1998-01-01

A revolution in diamond technology is in progress as the low-pressure process becomes an industrial reality. It will soon be possible to take advantage of the demanding properties of diamond to develop a myriad of new applications, particularly for self-lubricating, wear, and superhard coatings. The production of large diamond films or sheets at low cost, a distinct possibility in the not-too-distant future, may drastically change tribology technology, particularly solid lubricants and lubricating materials and systems. This chapter reviews the structures and properties of natural and synthetic diamond to gain a better understanding of the tribological properties of diamond and related materials to be described in the following chapters. Atomic and crystal structure, impurities, mechanical properties, and indentation hardness of diamond are described.

Structures and Mechanical Properties of Natural and Synthetic Diamonds

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1998-01-01

A revolution in the diamond technology is in progress, as the low-pressure process becomes an industrial reality. It will soon be possible to take advantage of the demanding properties of diamond to develop a myriad of new applications, particularly for self-lubricating, wear-resistant, and superhard coatings. The production of large diamond films or sheets at low cost, a distinct possibility in the not-too-distant future, may drastically change tribology technology, particularly regarding solid lubricants and lubricating materials and systems. This paper reviews the structures and properties of natural and synthetic diamonds to gain a better understanding of the tribological properties of diamond and related materials. Atomic and crystal structure, impurities, mechanical properties, and indentation hardness of diamond are described.

The effect of immersion time to low carbon steel hardness and microstructure with hot dip galvanizing coating method

NASA Astrophysics Data System (ADS)

Hakim, A. A.; Rajagukguk, T. O.; Sumardi, S.

2018-01-01

Along with developing necessities of metal materials, these rise demands of quality improvements and material protections especially the mechanical properties of the material. This research used hot dip galvanizing coating method. The objectives of this research were to find out Rockwell hardness (HRb), layer thickness, micro structure and observation with Scanning Electron Microscope (SEM) from result of coating by using Hot Dip Galvanizing coating method with immersion time of 3, 6, 9, and 12 minutes at 460°C. The result shows that Highest Rockwell hardness test (HRb) was at 3 minutes immersion time with 76.012 HRb. Highest thickness result was 217.3 μm at 12 minutes immersion. Microstructure test result showed that coating was formed at eta, zeta, delta and gamma phases, while Scanning Electron Microscope (SEM) showed Fe, Zn, Mn, Si and S elements at the specimens after coating.

Motion of a rigid sphere through an elastic tube with a lubrication film

NASA Astrophysics Data System (ADS)

Tani, Marie; Cambau, Thomas; Bico, Jose; Reyssat, Etienne

2017-11-01

The motion of large objects through narrow tubes is a common problem in physiology and more generally in the biological world. We built a model experiment where a rigid sphere is moved inside a narrower elastic tube coated with a lubricating fluid. The friction force is generally lower than in a non-lubricated situation. Interestingly, the force increases with the pulling velocity to the power 1/3, and also depends on the viscosity of the lubricant, the geometry and the mechanical properties of the tube. All our experimental data are well described by a scaling law combining lubrication and elasticity equations. We furthermore measured the thickness of the lubricant film. We present all these results.

Determination of physical and chemical states of lubricants in concentrated contacts, part 3

NASA Technical Reports Server (NTRS)

Lauer, J. L.; Keller, L. E.

1983-01-01

Solid and liquid thin films were analyzed by infrared emission Fourier microspectrophotometry. The apparatus used is a commercial absorption instrument modified to an emission instrument, comprising a rotating polarizing device, a miniature blackbody temperature reference adjustable in temperature and radiant flux and a microscope lens with a high numerical aperture in the entrance system for increased sensitivity and resolution. Studies of lubricant behavior in a simulated ball bearing showed the alignment of the fluid molecules in the Hertzian area. Polyphenyl ether plus 1% 1,1,2-trichloroethane (TCE) required lower shear rates for the same degree of alignment than without TCE. The experiment was run with 440 C stainless steel balls coated with TiN, a chemically inert material. In both cases, the alignment was strongly influenced by the presence of TCE. The results showed (1) the dependence of alignment of fluid molecules on flow and not on adsorption at metallic surfaces, (2) phase separation between lubricant and additive under high pressure which results in two phase flow and (3) reduction in traction of torque transmitting (traction) fluids.

Friction and wear properties of three hard refractory coatings applied by radiofrequency sputtering

NASA Technical Reports Server (NTRS)

Brainard, W. A.

1977-01-01

The adherence, friction, and wear properties of thin hard refractory compound coatings applied to 440C bearing steel by radiofrequency sputtering were investigated. Friction and wear tests were done with nonconforming pin on disk specimens. The compounds examined were chromium carbide, molybdenum silicide, and titanium carbide. The adherence, friction, and wear were markedly improved by the application of a bias voltage to the bearing steel substrate during coating deposition. Analysis by X-ray photoelectron spectroscopy indicated that the improvement may be due to a reduction in impurities in bias deposited coatings. A fivefold reduction in oxygen concentration in MoSi2 coating by biasing was noted. Chromium carbide was not effective as an antiwear coating. Molybdenum silicide provided some reduction in both friction and wear. Titanium carbide exhibited excellent friction and antiwear properties at light loads. Plastic flow and transfer of the coating material onto the pin specimen appears to be important in achieving low friction and wear.

Study on the property of low friction complex graphite-like coating containing tantalum

NASA Astrophysics Data System (ADS)

Wang, Zuoping; Feng, Lajun; Shen, Wenning

2018-03-01

In order to enhance equipment lifetime under low oil or even dry conditions, tantalum was introduced into the graphite-like coating (GLC) by sputtering mosaic targets. The results showed that the introduction of Ta obviously reduced the friction coefficient and hardness of the GLC, while improved the wearability. When the atomic percentage of Ta was larger than 3%, the steady friction coefficient was lower than 0.01, suggesting the coating exhibited super lubricity. When the content of Ta was about 5.0%, the average friction coefficient was 0.02 by a sliding friction test under load of 20 N in unlubricated condition. Its average friction coefficient reduced by 75%, compared with that of control GLC (0.0825).

Wear characteristics of bonded solid film lubricant under high load condition

NASA Technical Reports Server (NTRS)

Hiraoka, Naofumi; Sasaki, Akira; Kawashima, Noritsugu; Honda, Toshio

1991-01-01

Wear properties of phenolic resin bonded molybdenum disulfide film lubricant were studied. In-vacuo journal bearing tests were performed to evaluate the wear-life of this film lubricant. The wear-life depends on substrate materials and on sliding velocity. Pretreated substrate surfaces were examined to reveal the reasons for these results. Additionally, investigations on film wear mechanisms were made.

Influence of trimethylsilane flow on the microstructure, mechanical and tribological properties of CrSiCN coatings in water lubrication

NASA Astrophysics Data System (ADS)

Wu, Zhiwei; Zhou, Fei; Wang, Qianzhi; Zhou, Zhifeng; Yan, Jiwang; Li, Lawrence Kwok-Yan

2015-11-01

CrSiCN coatings with different silicon and carbon contents were deposited on silicon wafers and 316L stainless steels using unbalanced magnetron sputtering via adjusting trimethylsilane (TMS) flow, and their microstructure and mechanical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy(SEM), X-ray photoelectrons spectroscopy(XPS) and nano-indenter, respectively. The tribological properties of CrSiCN coatings sliding against SiC balls in water were investigated using ball-on-disk tribometer. The results showed that the CrSiCN coatings had fine composite microstructure consisting of nanocrystallites of Cr(C, N) crystal and amorphous phases such as a-Si3N4 and a-C(a-CNx). The typical columnar structures changed from fine cluster to coarse ones when the Si content was beyond 3.4 at.%. With an increase in the TMS flow, the hardness and Young's modulus of Corsican coatings all first increased, and then rapidly decreased, but the compressive stress in the coatings varied in the range of 2.8-4.8 GPa. When the TMS flow was 10 sccm, the CrSiCN coatings exhibited the highest hardness of 21.3 GPa and the lowest friction coefficient (0.11) and wear rate (8.4 × 10-8 mm3/N m). But when the TMS flow was beyond 15 sccm, the tribological properties of CrSiCN coatings in water became poor.

An evaluation of surface properties and frictional forces generated from Al-Mo-Ni coating on piston ring

NASA Astrophysics Data System (ADS)

Karamış, M. B.; Yıldızlı, K.; Çakırer, H.

2004-05-01

Surface properties of the Al-Mo-Ni coating plasma sprayed on the piston ring material and the frictional forces obtained by testing carried out under different loads, temperatures and frictional conditions were evaluated. Al-Mo-Ni composite material was deposited on the AISI 440C test steel using plasma spraying method. The coated and uncoated samples were tested by being exposed to frictional testing under dry and lubricated conditions. Test temperatures of 25, 100, 200, and 300 °C and loads of 83, 100, 200, and 300 N were applied during the tests in order to obtain the frictional response of the coating under conditions similar to real piston ring/cylinder friction conditions. Gray cast iron was used as a counterface material. All the tests were carried out with a constant sliding speed of 1 m/s. The properties of the coating were determined by using EDX and SEM analyses. Hardness distribution on the cross-section of the coating was also determined. In addition, the variations of the surface roughness after testing with test temperatures and loads under dry and lubricated conditions were recorded versus sliding distance. It was determined that the surface roughness increased with increasing loads. It increased with temperature up to 200 °C and then decreased at 300 °C under dry test conditions. Under lubricated conditions, the roughness decreased under the loads of 100 N and then increased. The roughness decreased at 200 °C but below and above this point it increased with the test temperature. Frictional forces observed under dry and lubricated test conditions increased with load at running-in period of the sliding. The steady-state period was then established with the sliding distance as a normal situation. However, the frictional forces were generally lower at a higher test temperature than those at a lower test temperature. Surprisingly, the test temperature of 200 °C was a critical point for frictional forces and surface roughness.

Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool

PubMed Central

Fox-Rabinovich, German; Locks Junior, Edinei; Stolf, Pietro; Matos Martins, Marcelo

2018-01-01

In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si3N4 nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds. PMID:29495620

Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool.

PubMed

Paiva, Jose Mario; Fox-Rabinovich, German; Locks Junior, Edinei; Stolf, Pietro; Seid Ahmed, Yassmin; Matos Martins, Marcelo; Bork, Carlos; Veldhuis, Stephen

2018-02-28

In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si₃N₄ nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

Shear thickening in suspensions: the lubricated-to-frictional contact scenario

NASA Astrophysics Data System (ADS)

Morris, Jeffrey

2017-11-01

Suspensions of solid particles in viscous liquids can vary from low-viscosity liquids to wet granular materials or soft solids depending on the solids loading and the forces acting between particles. When the particles are very concentrated, these mixtures are ''dense suspensions.'' Dense suspensions often exhibit shear thickening, an increase in apparent viscosity as the shear rate is increased. In its most extreme form, order of magnitude increases in viscosity over such a narrow range in shear rate occur that the term discontinuous shear thickening (DST) is applied. DST is particularly striking as it occurs in the relatively simple case of nearly hard spheres in a Newtonian liquid, and is found to take place for submicron particles in colloidal dispersions to much larger particle corn starch dispersions. We focus on simulations of a recently developed ``lubricated-to-frictional'' rheology in which the interplay of viscous lubrication, repulsive surface forces, and contact friction between particle surfaces provides a scenario to explain DST. Our simulation method brings together elements of the discrete-element method from granular flow with a simplified Stokesian Dynamics, and can rationalize not only the abrupt change in properties with imposed shear rate (or shear stress), but also the magnitude of the change. The large change in properties is associated with the breakdown of lubricating films between particles, with activation of Coulomb friction between particles. The rate dependence is caused by the shearing forces driving particles to contact, overwhelming conservative repulsive forces between surfaces; the repulsive forces are representative of colloidal stabilization by surface charge or steric effects, e.g. due to adsorbed polymer. The results of simulation are compared to developments by other groups, including a number of experimental studies and a theory incorporating the same basic elements as the simulation. The comparison to experiments of the

Soft lubrication

NASA Astrophysics Data System (ADS)

Skotheim, Jan; Mahadevan, Laksminarayanan

2004-11-01

We study the lubrication of fluid-immersed soft interfaces and show that elastic deformation couples tangential and normal forces and thus generates lift. We consider materials that deform easily, due to either geometry (e.g a shell) or constitutive properties (e.g. a gel or a rubber), so that the effects of pressure and temperature on the fluid properties may be neglected. Four different system geometries are considered: a rigid cylinder moving tangentially to a soft layer coating a rigid substrate; a soft cylinder moving tangentially to a rigid substrate; a cylindrical shell moving tangentially to a rigid substrate; and finally a journal bearing coated with a thin soft layer, which being a conforming contact allows us to gauge the influence of contact geometry. In addition, for the particular case of a soft layer coating a rigid substrate we consider both elastic and poroelastic material responses. Finally, we consider the role of contact geometry in the context of the journal bearing, a conforming contact. For all these cases we find the same generic behavior: there is an optimal combination of geometric and material parameters that maximizes the dimensionless normal force as a function of the softness.

Lubricant depletion under various laser heating conditions in Heat Assisted Magnetic Recording (HAMR)

NASA Astrophysics Data System (ADS)

Xiong, Shaomin; Wu, Haoyu; Bogy, David

2014-09-01

Heat assisted magnetic recording (HAMR) is expected to increase the storage areal density to more than 1 Tb/in2 in hard disk drives (HDDs). In this technology, a laser is used to heat the magnetic media to the Curie point (~400-600 °C) during the writing process. The lubricant on the top of a magnetic disk could evaporate and be depleted under the laser heating. The change of the lubricant can lead to instability of the flying slider and failure of the head-disk interface (HDI). In this study, a HAMR test stage is developed to study the lubricant thermal behavior. Various heating conditions are controlled for the study of the lubricant thermal depletion. The effects of laser heating repetitions and power levels on the lubricant depletion are investigated experimentally. The lubricant reflow behavior is discussed as well.

Promising Hard Carbon Coatings on Cu Substrates: Corrosion and Tribological Performance with Theoretical Aspect

NASA Astrophysics Data System (ADS)

Kumar, A. Madhan; Babu, R. Suresh; Obot, I. B.; Adesina, Akeem Yusuf; Ibrahim, Ahmed; de Barros, A. L. F.

2018-05-01

Protecting the surface of metals and alloys against corrosion and wear is of abundant importance owing to their widespread applications. In the present work, we report the improved anticorrosion and tribo-mechanical performance of copper (Cu) by a hard carbon (HC) coating synthesized in different pyrolysis temperature. Structural and surface characterization with roughness measurements was systematically investigated using various techniques. Effect of pyrolysis temperature on the corrosion behavior of coated Cu substrates in 0.6 M NaCl solution was evaluated via electrochemical impedance spectroscopy, potentiodynamic polarization. Pin-on-disk wear test of coated Cu substrate showed the influence of the pyrolysis temperature on the wear resistance performance of the HC coatings. According to the obtained results, it could be concluded that the HC coatings synthesized at 1100 °C revealed an enhanced comprehensive performance, revealing their possible utilization as a protective coating for Cu substrates in chloride environment. Monte Carlo simulations have been utilized to elucidate the interaction between the Cu surface and HC coatings.

Promising Hard Carbon Coatings on Cu Substrates: Corrosion and Tribological Performance with Theoretical Aspect

NASA Astrophysics Data System (ADS)

Kumar, A. Madhan; Babu, R. Suresh; Obot, I. B.; Adesina, Akeem Yusuf; Ibrahim, Ahmed; de Barros, A. L. F.

2018-01-01

Protecting the surface of metals and alloys against corrosion and wear is of abundant importance owing to their widespread applications. In the present work, we report the improved anticorrosion and tribo-mechanical performance of copper (Cu) by a hard carbon (HC) coating synthesized in different pyrolysis temperature. Structural and surface characterization with roughness measurements was systematically investigated using various techniques. Effect of pyrolysis temperature on the corrosion behavior of coated Cu substrates in 0.6 M NaCl solution was evaluated via electrochemical impedance spectroscopy, potentiodynamic polarization. Pin-on-disk wear test of coated Cu substrate showed the influence of the pyrolysis temperature on the wear resistance performance of the HC coatings. According to the obtained results, it could be concluded that the HC coatings synthesized at 1100 °C revealed an enhanced comprehensive performance, revealing their possible utilization as a protective coating for Cu substrates in chloride environment. Monte Carlo simulations have been utilized to elucidate the interaction between the Cu surface and HC coatings.

Fabrication of nitrogen-containing diamond-like carbon film by filtered arc deposition as conductive hard-coating film

NASA Astrophysics Data System (ADS)

Iijima, Yushi; Harigai, Toru; Isono, Ryo; Imai, Takahiro; Suda, Yoshiyuki; Takikawa, Hirofumi; Kamiya, Masao; Taki, Makoto; Hasegawa, Yushi; Tsuji, Nobuhiro; Kaneko, Satoru; Kunitsugu, Shinsuke; Habuchi, Hitoe; Kiyohara, Shuji; Ito, Mikio; Yick, Sam; Bendavid, Avi; Martin, Phil

2018-01-01

Diamond-like carbon (DLC) films, which are amorphous carbon films, have been used as hard-coating films for protecting the surface of mechanical parts. Nitrogen-containing DLC (N-DLC) films are expected as conductive hard-coating materials. N-DLC films are expected in applications such as protective films for contact pins, which are used in the electrical check process of integrated circuit chips. In this study, N-DLC films are prepared using the T-shaped filtered arc deposition (T-FAD) method, and film properties are investigated. Film hardness and film density decreased when the N content increased in the films because the number of graphite structures in the DLC film increased as the N content increased. These trends are similar to the results of a previous study. The electrical resistivity of N-DLC films changed from 0.26 to 8.8 Ω cm with a change in the nanoindentation hardness from 17 to 27 GPa. The N-DLC films fabricated by the T-FAD method showed high mechanical hardness and low electrical resistivity.

Lubrication System Failure Baseline Testing on an Aerospace Quality Gear Mesh

NASA Technical Reports Server (NTRS)

Handschuh, Robert F.; Morales, Wilfredo

2000-01-01

Aerospace drive systems are required to survive a loss-of-lubrication test for qualification. In many cases emergency lubrication systems need to be designed and utilized to permit the drive system to pass this difficult requirement. The weight of emergency systems can adversely affect the mission capabilities of the aircraft. The possibility to reduce the emergency system weight through the use of mist lubrication will be described. Mist lubrication involves the delivery of a minute amount of an organic liquid as a vapor or fine mist in flowing compressed air to rubbing surfaces. At the rubbing surface, the vapor or mist reacts to form a solid lubricating film. The aim of this study was to establish a baseline for gear behavior under oil depleted conditions. A reactive vapor-mist lubrication method is described and proposed as a candidate emergency lubrication system.

Influence of the coating process on the tribological conditions during cold forging with a MoS2 based lubricant

NASA Astrophysics Data System (ADS)

Lorenz, Robby; Hagenah, Hinnerk; Merklein, Marion

2018-05-01

Cold forging processes such as forward rod extrusion can be used to produce high quality components like connection rods, shafts and gears. The main advantages of these extruded components are sufficient surface quality, work hardening, compressive residual stresses and fatigue strength. Since one technical disadvantage of extruded components lies in the achievable tolerance classes, the improvement of these should be of crucial importance. For instance, the attainable workpiece accuracy and component quality can be influenced by adapting the tribological system in such a way that the resulting friction is specifically controlled in order to improve component forming. Lubricant modification is one practical way of adapting the tribological system to the requirements of the forming process. An industrial established and highly efficient lubricant system is the application of a zinc-phosphate conversion layer with a molybdenum disulfide-based lubricant. While offering many advantages, its tribological conditions seem to depend strongly on the layer weight and the application strategy. These parameters and the respective interdependencies have not been sufficiently investigated yet. In order to examine this, the tribological conditions depending on the layer weight are analyzed in greater detail using the Ring-Compression-Test (RCT). This tribometer provides a comparative representation of the forming conditions during cold forging. Furthermore, a potential dependency between the tribological conditions and two different coating techniques is analyzed. The latter are represented by the industrial standards dipping and dip-drumming.

Temperature effect of friction and wear characteristics for solid lubricating graphite

NASA Astrophysics Data System (ADS)

Kim, Yeonwook; Kim, Jaehoon

2015-03-01

Graphite is one of the effective lubricant additives due to its excellent high-temperature endurance and self-lubricating properties. In this study, wear behavior of graphite used as sealing materials to cut off hot gas is evaluated at room and elevated temperature. Wear occurs on graphite seal due to the friction of driving shaft and graphite. Thus, a reciprocating wear test to evaluate the wear generated for the graphite by means of the relative motion between a shaft material and a graphite seal was carried out. The friction coefficient and specific wear rate for the changes of applied load and sliding speed were compared under different temperature conditions considering the actual operating environment. Through SEM observation of the worn surface, the lubricating film was observed and compared with test conditions.

Characterization of Thermal Stability and High-Temperature Tribological Behavior of Electroless Ni-B Coating

NASA Astrophysics Data System (ADS)

Pal, Soupitak; Sarkar, Rohit; Jayaram, Vikram

2018-05-01

A preliminary study has been conducted using sequences of isothermal heat treatments and unidirectional high-temperature wear test following ball-on-flat geometry against an alumina counterface, to assess thermal stability and high-temperature tribological properties of the crystalline electroless Ni-B coating, a potential candidate for high-temperature solid lubricant coating. Isothermal heat treatment of 450 °C/15 h causes a significant amount of B diffusion into the Fe substrate without altering the coating's through-thickness hardness and nanostructure. At room temperature, a very low wear rate is observed, which increases up to two orders of magnitude above a testing temperature of 100 °C. Room-temperature wear behavior is mostly governed by oxidative wear, where friction-induced heating produces a thick oxide scale on the wear track, which subsequently decreases the wear rate by preventing direct contact between the coating and counterface. In the case of wear tests above 100 °C, removal of the same oxide layer occurs through local plastic deformation, essentially plastic ratcheting at the contacting region by flow softening of the contacting surface layer due to a local rise in temperature. Worn track morphology shows similarity with the severe wear seen in steel-steel contacts. Experimental observations have been explained and validated using the concept of contact point flash temperature. A quantitative assessment of contact point flash temperature has been carried out adopting the methodology, proposed by Ashby et al. The effects of applied normal load, test geometry, choice of counterface material, and testing temperatures on the transition of wear mechanism are critically discussed.

Application of Carbon Based Nano-Materials to Aeronautics and Space Lubrication

NASA Technical Reports Server (NTRS)

Street, Kenneth W., Jr.; Miyoshi, Kazuhisa; Wal, Randy L. Vander

2007-01-01

The tribology program at NASA Glenn Research Center in Cleveland, Ohio, is investigating carbon based nano-particles for their potential in advanced concept lubrication products. Service conditions range from high temperature atmospheric to low temperature vacuum. Some of the lubricants and surface coatings of tribological significance that we have evaluated include neat nano-particles, both grown in-situ and as bulk material deposited on the substrate, and nano-particles dispersed in oils which are all highly substrate interactive. We discuss results of testing these systems in a spiral orbit tribometer (SOT) and a unidirectional pin-on-disc (PoD) tribometer. A nano-onions/Krytox mixture evaluated as a lubricant for angular contact bearings in air caused a marked lowering of the coefficient of friction (CoF) (0.04 to 0.05) for the mixture with an eight-fold improvement in lifetime over that of the Krytox alone. In vacuum, no effect was observed from the nano-onions. Multi-walled nanotubes (MWNT) and graphitized MWNT were tested under sliding friction in both air and vacuum. The MWNT which were grown in-situ oriented normal to the sliding surface exhibited low CoF (0.04) and long wear lives. Bulk MWNT also generate low CoF (0.01 to 0.04, vacuum; and 0.06, air) and long wear life (>1 million orbits, vacuum; and >3.5 million, air). Dispersed graphitized MWNT were superior to MWNT and both were superior to aligned MWNT indicating that orientation is not an issue for solid lubrication. Single-walled nanotubes (SWNT) were modified by cutting into shorter segments and by fluorination. All SWNTs exhibited low CoF in air, with good wear lives. The SWNT with slight fluorination yielded an ultra-low CoF of 0.002 although the best wear life was attributed to the nascent SWNT.

Exploring hardness enhancement in superhard tungsten tetraboride-based solid solutions using radial X-ray diffraction

DOE PAGES

Xie, Miao; Mohammadi, Reza; Turner, Christopher L.; ...

2015-07-29

In this paper, we explore the hardening mechanisms in WB4-based solid solutions upon addition of Ta, Mn, and Cr using in situ radial X-ray diffraction techniques under nonhydrostatic pressure. By examining the lattice-supported differential strain, we provide insights into the mechanism for hardness increase in binary solid solutions at low dopant concentrations. Speculations on the combined effects of electronic structure and atomic size in ternary WB 4 solid solutions containing Ta with Mn or Cr are also included to understand the extremely high hardness of these materials.

Microstructure characterization of hypereutectoid aluminium bronze composite coating

NASA Astrophysics Data System (ADS)

Kucita, P.; Wang, S. C.; Li, W. S.; Cook, R. B.; Starink, M. J.

2015-10-01

Hypereutectoid aluminium bronze coating was deposited onto an E.N. 10503 steel substrate using plasma transferred arc welding (PTA). Microstructure characterisation of the coating and a section near the steel substrate joint was carried out using SEM, EBSD, EDS in conjunction with XRD and depth-sensing nano-indentation. The constituent phases in the coating were identified as: martensitic Cu3Al β1' phase, solid solution of Al in Cu α phase and the intermetallic Fe3Al κ1 phase. The region near the steel substrate was characterised by high hardness, large grains and presence of Cu precipitates. No cracks were observed in this region. The coating has high hardness of 4.9GPa and Young's modulus of 121.7GPa. This is attributed to homogeneous distribution of sub microns size Fe3Al intermetallic phase. The implications of the coating to the engineering application of sheet metal forming are discussed.

Method for reclaiming waste lubricating oils

DOEpatents

Whisman, Marvin L.; Goetzinger, John W.; Cotton, Faye O.

1978-01-01

A method for purifying and reclaiming used lubricating oils containing additives such as detergents, antioxidants, corrosion inhibitors, extreme pressure agents and the like and other solid and liquid contaminants by preferably first vacuum distilling the used oil to remove water and low-boiling contaminants, and treating the dried oil with a solvent mixture of butanol, isopropanol and methylethyl ketone which causes the separation of a layer of sludge containing contaminants, unspent additives and oxidation products. After solvent recovery, the desludged oil is then subjected to conventional lubricating oil refining steps such as distillation followed by decolorization and deodorization.

Influence of microstructure on hardness of plasma sprayed Al2O3-TiO2-MgO coatings with interface diffusion by heat treatment

NASA Astrophysics Data System (ADS)

Chen, Kunlun; Song, Peng; Li, Chao; Lu, Jiansheng

2017-12-01

The effect of heat treatment on the microstructure and mechanical properties of Al2O3-TiO2 coatings doped with 5 wt% MgO was investigated in this paper. The composite coatings were prepared by atmospheric plasma spraying (APS) and heat treated at 1000 °C for 24 h in Ar. The coatings were analyzed using scanning electron microscopy with electron probe x-ray microanalysis and x-ray diffraction. The hardness was determined using a Vickers hardness test on the as-sprayed coatings and after heat treatment. The results showed that the interface diffusion between the Al-rich and Ti-rich layers resulted in mutual pinning within the coating during the heat treatment. The newly formed MgAl2O4 phase promoted cracking-healing behavior within the coating. We conclude that increase of the hardness of the coatings was mainly caused by the mutual pinning interface and crack healing.

Dry rotary swaging with structured and coated tools

NASA Astrophysics Data System (ADS)

Herrmann, Marius; Schenck, Christian; Kuhfuss, Bernd

2018-05-01

Rotary swaging is a cold bulk forming process for manufacturing of complex bar and tube profiles like axles and gear shafts in the automotive industry. Conventional rotary swaging is carried out under intense use of lubricant usually based on mineral oil. Besides lubrication the lubricant fulfills necessary functions like lubrication, flushing and cooling, but generates costs for recycling, replacement and cleaning of the workpieces. Hence, the development of a dry process design is highly desirable, both under economic and ecological points of view. Therefore, it is necessary to substitute the functions of the lubricant. This was realized by the combination of newly developed a-C:H:W coating systems on the tools to minimize the friction and to avoid adhesion effects. With the application of a deterministic structure in the forging zone of the tools the friction conditions are modified to control the axial process forces. In this study infeed rotary swaging with functionalized tools was experimentally investigated. Therefore, steel and aluminum tubes were formed with and without lubricant. Different structures which were coated and uncoated were implemented in the reduction zone of the tools. The antagonistic effects of coating and structuring were characterized by measuring the axial process force and the produced workpiece quality in terms of roundness and surface roughness. Thus, the presented results allow for further developments towards a dry rotary swaging process.

The filling of powdered herbs into two-piece hard capsules using hydrogenated cotton seed oil as lubricant.

PubMed

Aling, Joanna; Podczeck, Fridrun

2012-11-20

The aim of this work was to investigate the plug formation and filling properties of powdered herbal leaves using hydrogenated cotton seed oil as an alternative lubricant. In a first step, unlubricated and lubricated herbal powders were studied on a small scale using a plug simulator, and low-force compression physics and parameterization techniques were used to narrow down the range in which the optimum amount of lubricant required would be found. In a second step these results were complemented with investigations into the flow properties of the powders based on packing (tapping) experiments to establish the final optimum lubricant concentration. Finally, capsule filling of the optimum formulations was undertaken using an instrumented tamp filling machine. This work has shown that hydrogenated cotton seed oil can be used advantageously for the lubrication of herbal leaf powders. Stickiness as observed with magnesium stearate did not occur, and the optimum lubricant concentration was found to be less than that required for magnesium stearate. In this work, lubricant concentrations of 1% or less hydrogenated cotton seed oil were required to fill herbal powders into capsules on the instrumented tamp-filling machine. It was found that in principle all powders could be filled successfully, but that for some powders the use of higher compression settings was disadvantageous. Relationships between the particle size distributions of the powders, their flow and consolidation as well as their filling properties could be identified by multivariate statistical analysis. The work has demonstrated that a combination of the identification of plug formation and powder flow properties is helpful in establishing the optimum lubricant concentration required using a small quantity of powder and a powder plug simulator. On an automated tamp-filling machine, these optimum formulations produced satisfactory capsules in terms of coefficient of fill weight variability and capsule weight

Friction surfaced Stellite6 coatings

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

Rao, K. Prasad; Damodaram, R.; Rafi, H. Khalid, E-mail: khalidrafi@gmail.com

2012-08-15

Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: Black-Right-Pointing-Pointer Stellite6 used as coating material formore » friction surfacing. Black-Right-Pointing-Pointer Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. Black-Right-Pointing-Pointer Finer and uniformly distributed carbides in friction surfaced coatings. Black-Right-Pointing-Pointer Absence of melting results compositional homogeneity in FS Stellite6 coatings.« less

Biofluid lubrication for artificial joints

NASA Astrophysics Data System (ADS)

Pendleton, Alice Mae

This research investigated biofluid lubrication related to artificial joints using tribological and rheological approaches. Biofluids studied here represent two categories of fluids, base fluids and nanostructured biofluids. Base fluids were studied through comparison of synthetic fluids (simulated body fluid and hyaluronic acid) as well as natural biofluids (from dogs, horses, and humans) in terms of viscosity and fluid shear stress. The nano-structured biofluids were formed using molecules having well-defined shapes. Understanding nano-structured biofluids leads to new ways of design and synthesis of biofluids that are beneficial for artificial joint performance. Experimental approaches were utilized in the present research. This includes basic analysis of biofluids' property, such as viscosity, fluid shear stress, and shear rate using rheological experiments. Tribological investigation and surface characterization were conducted in order to understand effects of molecular and nanostructures on fluid lubrication. Workpiece surface structure and wear mechanisms were investigated using a scanning electron microscope and a transmission electron microscope. The surface topography was examined using a profilometer. The results demonstrated that with the adding of solid additives, such as crown ether or fullerene acted as rough as the other solids in the 3-body wear systems. In addition, the fullerene supplied low friction and low wear, which designates the lubrication purpose of this particular particle system. This dissertation is constructed of six chapters. The first chapter is an introduction to body fluids, as mentioned earlier. After Chapter II, it examines the motivation and approach of the present research, Chapter III discusses the experimental approaches, including materials, experimental setup, and conditions. In Chapter IV, lubrication properties of various fluids are discussed. The tribological properties and performance nanostructured biofluids are

Hard Chrome-Coated and Fullerene-Doped Metal Surfaces in Orthopedic Bearings.

PubMed

Sonntag, Robert; Feige, Katja; Dos Santos, Claudia Beatriz; Kretzer, Jan Philippe

2017-12-20

Metal-on-metal bearings for total hip replacements have been introduced as an alternative to polyethylene in young and more active patients. These have, however, been shown to be prone to implant malpositioning and have been limited by some specific design features. In that context, coatings present an option to increase wear resistance by keeping the high fracture strength of the metal substrate. A custom-made electroplating setup was designed for the coating of CoCr substrates using (a) an industrial standard chromium electrolyte; (b) a custom-made hexavalent chromium (Cr 6+ ) electrolyte with a reduced chromium trioxide (CrO₃) content, both without solid additives and (c) with the addition of fullerene (C 60 ) nanoparticles; and (d) a trivalent chromium (Cr 3+ ) electrolyte with C 60 addition. All coatings showed an increase in microhardness compared with the metal substrate. Trivalent coatings were thinner (10 µm) than the hexavalent coatings (23-40 µm) and resulted in increased roughness and crack density. Wear was found to be reduced for the hexavalent chromium coatings by 70-84% compared with the CoCr-CoCr reference bearing while the trivalent chromium coating even increased wear by more than 300%. The addition of fullerenes to the electrolyte did not show any further tribological effect.

Hard Chrome-Coated and Fullerene-Doped Metal Surfaces in Orthopedic Bearings

PubMed Central

Feige, Katja; dos Santos, Claudia Beatriz; Kretzer, Jan Philippe

2017-01-01

Metal-on-metal bearings for total hip replacements have been introduced as an alternative to polyethylene in young and more active patients. These have, however, been shown to be prone to implant malpositioning and have been limited by some specific design features. In that context, coatings present an option to increase wear resistance by keeping the high fracture strength of the metal substrate. A custom-made electroplating setup was designed for the coating of CoCr substrates using (a) an industrial standard chromium electrolyte; (b) a custom-made hexavalent chromium (Cr6+) electrolyte with a reduced chromium trioxide (CrO3) content, both without solid additives and (c) with the addition of fullerene (C60) nanoparticles; and (d) a trivalent chromium (Cr3+) electrolyte with C60 addition. All coatings showed an increase in microhardness compared with the metal substrate. Trivalent coatings were thinner (10 µm) than the hexavalent coatings (23–40 µm) and resulted in increased roughness and crack density. Wear was found to be reduced for the hexavalent chromium coatings by 70–84% compared with the CoCr–CoCr reference bearing while the trivalent chromium coating even increased wear by more than 300%. The addition of fullerenes to the electrolyte did not show any further tribological effect. PMID:29261128

Virial coefficients of anisotropic hard solids of revolution: The detailed influence of the particle geometry

NASA Astrophysics Data System (ADS)

Herold, Elisabeth; Hellmann, Robert; Wagner, Joachim

2017-11-01

We provide analytical expressions for the second virial coefficients of differently shaped hard solids of revolution in dependence on their aspect ratio. The second virial coefficients of convex hard solids, which are the orientational averages of the mutual excluded volume, are derived from volume, surface, and mean radii of curvature employing the Isihara-Hadwiger theorem. Virial coefficients of both prolate and oblate hard solids of revolution are investigated in dependence on their aspect ratio. The influence of one- and two-dimensional removable singularities of the surface curvature to the mutual excluded volume is analyzed. The virial coefficients of infinitely thin oblate and infinitely long prolate particles are compared, and analytical expressions for their ratios are derived. Beyond their dependence on the aspect ratio, the second virial coefficients are influenced by the detailed geometry of the particles.

Virial coefficients of anisotropic hard solids of revolution: The detailed influence of the particle geometry.

PubMed

Herold, Elisabeth; Hellmann, Robert; Wagner, Joachim

2017-11-28

We provide analytical expressions for the second virial coefficients of differently shaped hard solids of revolution in dependence on their aspect ratio. The second virial coefficients of convex hard solids, which are the orientational averages of the mutual excluded volume, are derived from volume, surface, and mean radii of curvature employing the Isihara-Hadwiger theorem. Virial coefficients of both prolate and oblate hard solids of revolution are investigated in dependence on their aspect ratio. The influence of one- and two-dimensional removable singularities of the surface curvature to the mutual excluded volume is analyzed. The virial coefficients of infinitely thin oblate and infinitely long prolate particles are compared, and analytical expressions for their ratios are derived. Beyond their dependence on the aspect ratio, the second virial coefficients are influenced by the detailed geometry of the particles.

Preparation of multi-layer film consisting of hydrogen-free DLC and nitrogen-containing DLC for conductive hard coating

NASA Astrophysics Data System (ADS)

Iijima, Yushi; Harigai, Toru; Isono, Ryo; Degai, Satoshi; Tanimoto, Tsuyoshi; Suda, Yoshiyuki; Takikawa, Hirofumi; Yasui, Haruyuki; Kaneko, Satoru; Kunitsugu, Shinsuke; Kamiya, Masao; Taki, Makoto

2018-01-01

Conductive hard-coating films have potential application as protective films for contact pins used in the electrical inspection process for integrated circuit chips. In this study, multi-layer diamond-like carbon (DLC) films were prepared as conductive hard-coating films. The multi-layer DLC films consisting of DLC and nitrogen-containing DLC (N-DLC) film were prepared using a T-shape filtered arc deposition method. Periodic DLC/N-DLC four-layer and eight-layer films had the same film thickness by changing the thickness of each layer. In the ball-on-disk test, the N-DLC mono-layer film showed the highest wear resistance; however, in the spherical polishing method, the eight-layer film showed the highest polishing resistance. The wear and polishing resistance and the aggressiveness against an opponent material of the multi-layer DLC films improved by reducing the thickness of a layer. In multi-layer films, the soft N-DLC layer between hard DLC layers is believed to function as a cushion. Thus, the tribological properties of the DLC films were improved by a multi-layered structure. The electrical resistivity of multi-layer DLC films was approximately half that of the DLC mono-layer film. Therefore, the periodic DLC/N-DLC eight-layer film is a good conductive hard-coating film.

Tribology of the lubricant quantized sliding state.

PubMed

Castelli, Ivano Eligio; Capozza, Rosario; Vanossi, Andrea; Santoro, Giuseppe E; Manini, Nicola; Tosatti, Erio

2009-11-07

In the framework of Langevin dynamics, we demonstrate clear evidence of the peculiar quantized sliding state, previously found in a simple one-dimensional boundary lubricated model [A. Vanossi et al., Phys. Rev. Lett. 97, 056101 (2006)], for a substantially less idealized two-dimensional description of a confined multilayer solid lubricant under shear. This dynamical state, marked by a nontrivial "quantized" ratio of the averaged lubricant center-of-mass velocity to the externally imposed sliding speed, is recovered, and shown to be robust against the effects of thermal fluctuations, quenched disorder in the confining substrates, and over a wide range of loading forces. The lubricant softness, setting the width of the propagating solitonic structures, is found to play a major role in promoting in-registry commensurate regions beneficial to this quantized sliding. By evaluating the force instantaneously exerted on the top plate, we find that this quantized sliding represents a dynamical "pinned" state, characterized by significantly low values of the kinetic friction. While the quantized sliding occurs due to solitons being driven gently, the transition to ordinary unpinned sliding regimes can involve lubricant melting due to large shear-induced Joule heating, for example at large speed.

Interpretations of the Critical Indentation Depths in Soft Coatings on Hard Substrates from a Morphological Analysis on Nanocontact Impressions

NASA Astrophysics Data System (ADS)

Lee, Yun-Hee; Kim, Yongil; Ryu, Kwon Sang; Nahm, Seung Hoon; Yoon, Ki-Bong

2011-01-01

When a nanoindentation is carried out on a coating-substrate system, the resulting deformation can be influenced by not only the coating but also the substrate. In order to measure the coating-only contact properties, many works have been done to extract the critical indentation depth. In this study, we proposed a morphological parameter to determine the critical indentation depth by materializing interfacial constraints. From nanoindents were formed on 1.2-µm-thick Cu and Au coatings, several morphological parameters were analyzed such as remnant indentation volume, impression apex angle and apex bluntness. The critical relative depths of the Cu and Au coatings were, respectively, as 0.25 and 0.16 consistent with the results from the hardness and volumetric approach. In addition, the apex angle approach can explain the discrepancy between both hardness and volumetric approach because the new approach traces the ratio of superficial edge recovery and depth-directional shrinkage inside of an impression.

Dry Lubrication of High Temperature Silicon Nitride Rolling Contacts.

DTIC Science & Technology

1980-11-01

comparable to M50 bearing steel [2]. Quality control measures were implemented in the areas of raw material inspection as well as non-destructive evaluation...to oil lubricated bearing steels . Due to the apparent success of graphite at high tem- perature, three vendors were selected that manufacture graph...hybrid bearings ( steel rings and silicon nitride balls) to establish solid lubricant/cage design practices. High temperature bearing tests with silicon

Influence of Cobalt on the Adhesion Strength of Polycrystalline Diamond Coatings on WC-Co Hard Alloys

NASA Astrophysics Data System (ADS)

Linnik, S. A.; Gaidaichuk, A. V.; Okhotnikov, V. V.

2018-02-01

The influence of cobalt on the phase composition and adhesion strength of polycrystalline diamond coatings has been studied using scanning electron microscopy, Raman spectroscopy, and X-ray microanalysis. The coatings have been deposited on WC-Co hard alloy substrates in glow discharge plasma. It has been found that the catalytic amorphization of carbon only takes place during the direct synthesis of the diamond coating, when the cobalt vapor pressure over the substrate is high and the cobalt-related degradation of the synthesized diamond is absent.

Effect of fabrication parameters on coating properties of tubular solid oxide fuel cell electrolyte prepared by vacuum slurry coating

NASA Astrophysics Data System (ADS)

Son, Hui-Jeong; Song, Rak-Hyun; Lim, Tak-Hyoung; Lee, Seung-Bok; Kim, Sung-Hyun; Shin, Dong-Ryul

The process of vacuum slurry coating for the fabrication of a dense and thin electrolyte film on a porous anode tube is investigated for application in solid oxide fuel cells. 8 mol% yttria stabilized zirconia is coated on an anode tube by vacuum slurry-coating process as a function of pre-sintering temperature of the anode tube, vacuum pressure, slurry concentration, number of coats, and immersion time. A dense electrolyte layer is formed on the anode tube after final sintering at 1400 °C. With decrease in the pre-sintering temperature of the anode tube, the grain size of the coated electrolyte layer increases and the number of surface pores in the coating layer decreases. This is attributed to a reduced difference in the respective shrinkage of the anode tube and the electrolyte layer. The thickness of the coated electrolyte layer increases with the content of solid powder in the slurry, the number of dip-coats, and the immersion time. Although vacuum pressure has no great influence on the electrolyte thickness, higher vacuum produces a denser coating layer, as confirmed by low gas permeability and a reduced number of defects in the coating layer. A single cell with the vacuum slurry coated electrolyte shows a good performance of 620 mW cm -2 (0.7 V) at 750 °C. These experimental results indicate that the vacuum slurry-coating process is an effective method to fabricate a dense thin film on a porous anode support.

Establishment of Wear Resistant HVOF Coatings for 50CrMo4 Chromium Molybdenum Alloy Steel as an Alternative for Hard Chrome Plating

NASA Astrophysics Data System (ADS)

Karuppasamy, S.; Sivan, V.; Natarajan, S.; Kumaresh Babu, S. P.; Duraiselvam, M.; Dhanuskodi, R.

2018-05-01

High cost imported components of seamless steel tube manufacturing plants wear frequently and need replacement to ensure the quality of the product. Hard chrome plating, which is time consuming and hazardous, is conventionally used to restore the original dimension of the worn-out surface of the machine components. High Velocity Oxy-Fuel (HVOF) thermal spray coatings with NiCrBSi super alloy powder and Cr3C2 NiCr75/25 alloy powder applied on a 50CrMo4 (DIN-1.7228) chromium molybdenum alloy steel, the material of the wear prone machine component, were evaluated for use as an alternative for hard chrome plating in this present work. The coating characteristics are evaluated using abrasive wear test, sliding wear test and microscopic analysis, hardness test, etc. The study results revealed that the HVOF based NiCrBSi and Cr3C2NiCr75/25 coatings have hardness in the range of 800-900 HV0.3, sliding wear rate in the range of 50-60 µm and surface finish around 5 microns. Cr3C2 NiCr75/25 coating is observed to be a better option out of the two coatings evaluated for the selected application.

Selection and Application of Liquid and Semi-Solid Lubricants in Aerospace Vehicles and Supporting Equipment

DTIC Science & Technology

1965-10-01

lubrication method even though the Correct lubricant and method of xubrioation were readily available with a long history of successful operation under...grease has failed. During the discussion of the lubricant failure it is disclosed that the failure is due to corrosion of titani ™ *etal located

Two feasible approaches to enhance the wear behaviors of NiCrBSi coating in atmosphere and aqueous environments

NASA Astrophysics Data System (ADS)

Ye, Yuwei; Wang, Chunting; Zheng, Wenru; Xiong, Wei; Wang, Yongxin; Li, Xiaogang

2017-09-01

NiCrBSi coating was deposited successfully on the surface of 316 stainless steel substrate by means of plasma spraying. The microstructures and mechanical property were analyzed by scanning electron microscopy, x-ray diffraction, and a Vickers hardness tester. The wear performances of the coatings sliding against the GCr15 ball under ambient air and water conditions were investigated, and two feasible approaches (tungsten carbide (WC)-doping and heat treatment) were used to improve the tribological performance. Results showed that the hardness of the NiCrBSi coating increased by 12.5% and 28.5% and the porosity decreased by 26.1% and 47.8%, respectively, after WC-doping and heat treatment. During dry friction, the friction coefficient and wear rate of the NiCrBSi coating were about 0.47 and 1.4  ×  10-5 mm3 N-1 m-1, respectively. These values were higher than those obtained on other coatings. In water conditions, all coatings showed a lower friction and wear rate than that in ambient air, which was as a result of the lubrication effect of water. Significantly, with WC-doping and heat treatment, the friction coefficients of both coatings were about 18.5% and 36.7%, respectively, lower than that of the NiCrBSi coating. Furthermore, the wear rates of both coatings were about 20% and 70%, respectively, lower than that of the NiCrBSi coating.

GIOTTO's antenna de-spin mechanism: Ots lubrication and thermal vacuum performance

NASA Technical Reports Server (NTRS)

Todd, M. J.; Parker, K.

1987-01-01

Except in the near Earth phase of GIOTTO's mission to Comet Halley, the HGA (high gain antenna) on board GIOTTO was the only designed means of up/down communications. The spacecraft spin stabilization required that the HGA be despun at the same rotational rate of nominally 15 rpm in order to keep the HGA pointing accurately to a Earth. A dual servomotor despin mechanism was designed and built by SEP of France for this purpose. The expected thermal environment suggested that dry lubrication was preferable to wet for the ball bearings but there existed no relevant data on the torque noise spectrum of candidate solid lubricants. Therefore ad hoc torque noise tests were run with two solid lubricants: ion plated lead film plus lead bronze cage (retainer) and a PTFE composite cage only. The lead lubrication showed the better spectrum up to the mission lifetime point so it was selected for continued test over some 20 times the Halley mission life, with periodic torque spectrum monitoring. The spectrum remained well within the pointing error budget over the 100 million revolutions covered.

Electrostatic powder coatings of pristine graphene: A new approach for coating of granular and fibril substrates

NASA Astrophysics Data System (ADS)

Nine, Md J.; Kabiri, Shervin; Tung, Tran Thanh; Tran, Diana N. H.; Losic, Dusan

2018-05-01

The use of pristine graphene (pG) based on solution processed coating technologies is often limited by their poor dispersibility in water and organic solvents which prevents to achieve the best performing properties of pG in coating applications. To address these limitations, we developed a dispersant-free coating approach of pG based on their intrinsic solid-lubricity and interlayer electrostatic interactions. The "rotating drum" method was established to provide suitable conditions for electrostatic deposition of pG-powder which is demonstrated on two model substrates with granular and fibril morphologies (urea and acrylic fibers) to improve their physical and electrical properties. The results showed that the pG coating enables to minimize moisture induced caking tendency of commercial urea prills at a relative humidity (RH) of 85% (higher than critical humidity) exhibiting greater moisture rejection ability (∼2 times higher than uncoated urea) and to improve their anti-abrasive properties. The pG-powder coating applied on nonconductive acrylic fibers provides a stable conductive layer (∼0.8 ± 0.1 kΩ/sq) which made them suitable for using in wearable electronics, sensors and electromagnetic interference (EMI) shielding. The developed coating method for pG-powder based on "rotating drum" is generic, simple, eco-friendly, low-cost, and scalable for broad range of coating applications.

Solid hydrogen coated graphite particles in the interstellar medium. I.

NASA Technical Reports Server (NTRS)

Swamy, K. S. K.; Wickramasinghe, N. C.

1969-01-01

Solid para hydrogen coated graphite particles expulsion into interstellar medium from star formation regions, considering mantles stability and particles extinction efficiency, albedo and phase function

Program for plasma-sprayed self-lubricating coatings

NASA Technical Reports Server (NTRS)

Walther, G. C.

1979-01-01

A method for preparing composite powders of the three coating components was developed and a procedure that can be used in applying uniform coatings of the composite powders was demonstrated. Composite powders were prepared by adjusting particle sizes of the components and employing a small amount of monoaluminum phosphate as an inorganic binder. Quantitative microscopy (image analysis) was found to be a convenient method of characterizing the composition of the multiphase plasma-sprayed coatings. Area percentages and distribution of the components were readily obtained by this method. The adhesive strength of the coating to a nickel-chromium alloy substrate was increased by about 40 percent by a heat treatment of 20 hours at 650 C.

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.

Zwitterionic Nanofibers of Super-Glue for Transparent and Biocompatible Multi-Purpose Coatings

NASA Astrophysics Data System (ADS)

Mele, Elisa; Heredia-Guerrero, José A.; Bayer, Ilker S.; Ciofani, Gianni; Genchi, Giada G.; Ceseracciu, Luca; Davis, Alexander; Papadopoulou, Evie L.; Barthel, Markus J.; Marini, Lara; Ruffilli, Roberta; Athanassiou, Athanassia

2015-09-01

Here we show that macrozwitterions of poly(ethyl 2-cyanoacrylate), commonly called Super Glue, can easily assemble into long and well defined fibers by electrospinning. The resulting fibrous networks are thermally treated on glass in order to create transparent coatings whose superficial morphology recalls the organization of the initial electrospun mats. These textured coatings are characterized by low liquid adhesion and anti-staining performance. Furthermore, the low friction coefficient and excellent scratch resistance make them attractive as solid lubricants. The inherent texture of the coatings positively affects their biocompatibility. In fact, they are able to promote the proliferation and differentiation of myoblast stem cells. Optically-transparent and biocompatible coatings that simultaneously possess characteristics of low water contact angle hysteresis, low friction and mechanical robustness can find application in a wide range of technological sectors, from the construction and automotive industries to electronic and biomedical devices.

Zwitterionic Nanofibers of Super-Glue for Transparent and Biocompatible Multi-Purpose Coatings

PubMed Central

Mele, Elisa; Heredia-Guerrero, José A.; Bayer, Ilker S.; Ciofani, Gianni; Genchi, Giada G.; Ceseracciu, Luca; Davis, Alexander; Papadopoulou, Evie L.; Barthel, Markus J.; Marini, Lara; Ruffilli, Roberta; Athanassiou, Athanassia

2015-01-01

Here we show that macrozwitterions of poly(ethyl 2-cyanoacrylate), commonly called Super Glue, can easily assemble into long and well defined fibers by electrospinning. The resulting fibrous networks are thermally treated on glass in order to create transparent coatings whose superficial morphology recalls the organization of the initial electrospun mats. These textured coatings are characterized by low liquid adhesion and anti-staining performance. Furthermore, the low friction coefficient and excellent scratch resistance make them attractive as solid lubricants. The inherent texture of the coatings positively affects their biocompatibility. In fact, they are able to promote the proliferation and differentiation of myoblast stem cells. Optically-transparent and biocompatible coatings that simultaneously possess characteristics of low water contact angle hysteresis, low friction and mechanical robustness can find application in a wide range of technological sectors, from the construction and automotive industries to electronic and biomedical devices. PMID:26357936

Tribological evaluation and analysis of coating materials

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1992-01-01

A physical characterization of coating materials by analytical techniques such as XPS, AES, ellipsometry, and nuclear reaction analysis can contribute to the understanding of adhesion and friction of the coatings and can partially predict the tribological properties of the coatings. This two-part paper describes the tribological properties and physical characteristics of (1) diamondlike carbon (DLC) films and (2) silicon nitride (SiN(x)) films. Emphasis is to relate plasma deposition conditions to the film chemistry and composition and to the adhesion and friction of the films. With the DLC films, the higher the plasma deposition power, the less the hydrogen concentration and the greater the film density and the hardness. The friction behavior of DLC films deposited at higher deposition powers (200 to 300 W) is similar to that of bulk diamond. Even in a vacuum, the DLC films effectively lubricate ceramic surfaces (Si3N4) at temperatures to 500 C. With SiN(x) films, the silicon to nitrogen ratios and the amount of amorphous silicon depend on deposition frequency. The presence of rich amorphous silicon in the high-frequency plasma-deposited SiN(x) films increases their adhesion and friction above 500 C in vacuum.

Experience with synthetic fluorinated fluid lubricants

NASA Technical Reports Server (NTRS)

Conley, Peter L.; Bohner, John J.

1990-01-01

Since the late 1970's, the wet lubricant of choice for space mechanisms has been one of the family of synthetic perfluoro polyalkylether (PFPE) compounds, namely Fomblin Z-25 (Bray-815Z) or DuPont's Krytox 143xx series. While offering the advantages of extremely low vapor pressures and wide temperature ranges, these oils and derived greases have a complex chemistry compared to the more familiar natural and synthetic hydrocarbons. Many aerospace companies have conducted test programs to characterize the behavior of these compounds in a space environment, resulting in a large body of hard knowledge as well as considerable space lore concerning the suitability of the lubricants for particular applications and techniques for successful application. The facts are summarized and a few myths about the compounds are dispelled, and some performance guidelines for the mechanism design engineer are provided.

The effect of load in a contact with boundary lubrication. [reduction of coefficient of friction

NASA Technical Reports Server (NTRS)

Georges, J. M.; Lamy, B.; Daronnat, M.; Moro, S.

1978-01-01

The effect of the transition load on the wear in a contact with boundary lubrication was investigated. An experimental method was developed for this purpose, and parameters affecting the boundary lubrication under industrial operating conditions were identified. These parameters are the adsorbed boundary film, the contact microgeometry (surface roughness), macrogeometry, and hardness of materials used. It was found that the curve of the tops of the surface protrustion affect the transition load, and thus the boundary lubrication. The transition load also depends on the chemical nature of the contact and its geometrical and mechanical aspects.

Comparison of surface roughness and chip characteristics obtained under different modes of lubrication during hard turning of AISI H13 tool work steel.

NASA Astrophysics Data System (ADS)

Raj, Anil; Wins, K. Leo Dev; Varadarajan, A. S.

2016-09-01

Surface roughness is one of the important parameters, which not only affects the service life of a component but also serves as a good index of machinability. Near Dry Machining, methods (NDM) are considered as sustainable alternative for workshops trying to bring down their dependence on cutting fluids and the hazards associated with their indiscriminate usage. The present work presents a comparison of the surface roughness and chip characteristics during hard turning of AISI H13 tool work steel using hard metal inserts under two popular NDM techniques namely the minimal fluid application and the Minimum Quantity Lubrication technique(MQL) using an experiment designed based on Taguchi's techniques. The statistical method of analysis of variance (ANOVA) was used to determine the relative significance of input parameters consisting of cutting speed, feed and depth of cut on the attainable surface finish and the chip characteristics. It was observed that the performance during minimal fluid application was better than that during MQL application.

Modification of Bushing Test Rig and Research of Variable Inlet Guide Vane Bushings For Further Development of PM304 Bushings

NASA Technical Reports Server (NTRS)

Yanke, Anne

2004-01-01

PS304 is a high temperature solid lubricant coating comprised of a nickel-chrome binder, chrome oxide hardener, barium-calcium fluoride high temperature lubricant, and silver as the low temperature lubricant. This coating is used to lubricate Oil-Free Foil Air Bearings as they experience friction and wear during start up and shut down. The coating deposition process begins with undercutting the shaft. This area is then sandblasted to provide a rough surface for the coating to adhere to. The coating powder is then sent through the plasma spray gun and a reasonably thick layer is applied to the undercut area of the shaft. The coating is then ground down even with the surface of the shaft and gets a nice polished finish. The foil air bearings use the solid lubricant, as mentioned above, during start up and shut down. During normal operating conditions, generally above 2000RPM, the bearings utilize air as their lubricant. Foil air bearings are comprised of a thin top foil and a corrugated bump foil. They have an interference fit with the shaft before operation. As the air gets "trapped" between the top foil and the shaft, it presses the top foil against the bump foil, in turn compressing the bumps. As the bumps compress, it allows for the air to separate the top foil from the shaft, therefore, utilizing the trapped air as its lubricant.

High-temperature seals and lubricants for geothermal rock bits. Final report

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

Hendrickson, R.R.; Winzenried, R.W.; Jones A.H.

1981-04-01

High temperature seals (elastomeric and mechanical) and lubricants were developed specifically for journal-type rock bits to be used in geothermal well drilling. Results at simulated downhole conditions indicate that five selected elastomeric seals (L'Garde No. 267, Utex Nos. 227, 231 and HTCR, and Sandia Glow Discharge Coated Viton) are capable of 288/sup 0/C (500/sup 0/F) service. Two prototype mechanical seals did not achieve the life determined for the elastomeric seals. Six lubricants (Pacer PLX-024 oil, PLX-043 oil, PLX-045 oil, Geobond Oil, and Geobond Grease) demonstrated 316/sup 0/C (600/sup 0/F) capability. Recommendation is made for full-scale simulated geothermal drilling tests utilizingmore » the improved elastomeric seals and lubricants.« less

Space Coatings for Industry

NASA Technical Reports Server (NTRS)

1980-01-01

Ball Aerospace developed entirely new space lubrication technologies. A new family of dry lubricants emerged from Apollo, specifically designed for long life in space, together with processes for applying them to spacecraft components in microscopically thin coatings. Lubricants worked successfully on seven Orbiting Solar Observatory flights over the span of a decade and attracted attention to other contractors which became Ball customers. The company has developed several hundred variations of the original OSO technology generally designed to improve the quality and useful life of a wide range of products or improve efficiency of the industrial processes by which such products are manufactured.

Characterization of Lubricants on Ball Bearings by FT-IR Using an Integrating Sphere

NASA Technical Reports Server (NTRS)

Street, K. W.; Pepper, S. V.; Wright, A. A.; Grady, B.

2007-01-01

Fourier Transform-Infrared reflectance microspectroscopy has been used extensively for the examination of coatings on nonplanar surfaces such as ball bearings. While this technique offers considerable advantages, practical application has many drawbacks, some of which are easily overcome by the use of integrating sphere technology. This paper describes the use of an integrating sphere for the quantification of thin layers of lubricant on the surface of ball bearings and the parameters which require optimization in order to obtain reliable data. Several applications of the technique are discussed including determination of lubricant load on 12.7 mm steel ball bearings and the examination of degraded lubricant on post mortem specimens.

Origins of extreme boundary lubrication by phosphatidylcholine liposomes.

PubMed

Sorkin, Raya; Kampf, Nir; Dror, Yael; Shimoni, Eyal; Klein, Jacob

2013-07-01

Phosphatidylcholine (PC) vesicles have been shown to have remarkable boundary lubricating properties under physiologically-high pressures. Here we carry out a systematic study, using a surface force balance, of the normal and shear (frictional) forces between two opposing surfaces bearing different PC vesicles across water, to elucidate the origin of these properties. Small unilamellar vesicles (SUVs, diameters < 100 nm) of the symmetric saturated diacyl PCs DMPC (C(14)), DPPC (C(16)) and DSPC (C(18)) attached to mica surfaces were studied in their solid-ordered (SO) phase on the surface. Overall liposome lubrication ability improves markedly with increasing acyl chain length, and correlates strongly with the liposomes' structural integrity on the substrate surface: DSPC-SUVs were stable on the surface, and provided extremely efficient lubrication (friction coefficient μ ≈ 10(-4)) at room temperature at pressures up to at least 18 MPa. DMPC-SUVs ruptured following adsorption, providing poor high-pressure lubrication, while DPPC-SUVs behavior was intermediate between the two. These results can be well understood in terms of the hydration-lubrication paradigm, but suggest that an earlier conjecture, that highly-efficient lubrication by PC-SUVs depended simply on their being in the SO rather than in the liquid-disordered phase, should be more nuanced. Our results indicate that the resistance of the SUVs to mechanical deformation and rupture is the dominant factor in determining their overall boundary lubrication efficiency in our system. Copyright © 2013 Elsevier Ltd. All rights reserved.

Properties of Extruded PS-212 Type Self-Lubricating Materials

NASA Technical Reports Server (NTRS)

Waters, W. J.; Sliney, H. E.; Soltis, R. F.

1993-01-01

Research has been underway at the NASA Lewis Research Center since the 1960's to develop high temperature, self-lubricating materials. The bulk of the research has been done in-house by a team of researchers from the Materials Division. A series of self-lubricating solid material systems has been developed over the years. One of the most promising is the composite material system referred to as PS-212 or PM-212. This material is a powder metallurgy product composed of metal bonded chromium carbide and two solid lubricating materials known to be self-lubricating over a wide temperature range. NASA feels this material has a wide potential in industrial applications. Simplified processing of this material would enhance its commercial potential. Processing changes have the potential to reduce processing costs, but tribological and physical properties must not be adversely affected. Extrusion processing has been employed in this investigation as a consolidation process for PM-212/PS-212. It has been successful in that high density bars of EX-212 (extruded PM-212) can readily be fabricated. Friction and strength data indicate these properties have been maintained or improved over the P.M. version. A range of extrusion temperatures have been investigated and tensile, friction, wear, and microstructural data have been obtained. Results indicate extrusion temperatures are not critical from a densification standpoint, but other properties are temperature dependent.

A study of lubrication, processing conditions, and material combinations that affect the wear of micro-textured-carbide coated cobalt-chromium-molybdenum alloy surfaces used for artificial joints implants

NASA Astrophysics Data System (ADS)

Ettienne-Modeste, Geriel A.

Total joint replacement remains one of the most successful treatments for arthritis. The most common materials used for artificial joints are metals (e.g., cobalt-chrome alloys or titanium alloys), which articulate against ultra-high molecular weight polyethylene. Wear related failures of artificial joints may be reduced with the use of novel micro-textured carbide surfaces. The micro-textured carbide surfaces were deposited on a CoCrMo alloy using microwave plasma-assisted chemical vapor deposition. Wear tests were conducted to determine wear mechanisms and properties of the micro-textured surfaces. The research presented in this thesis addresses: (1) rheolgoical behavior of bovine calf serum with and without antibacterial agents to determine whether they can be used as appropriate models for synovial fluid, (2) the wear behavior of the micro-textured CoCrMo surface system, and (3) the mechanical and material properties of the micro-textured CoCrMo alloy surface relevant to wear performance. The rheological studies showed that the apparent viscosity of bovine calf serum increased with an increase in concentration before and after the serum was used for wear testing. The wear analysis showed that the processing conditions (2hr deposition vs. 4hr deposition times) affected the wear properties. The 2hr carbide-on-carbide lubricated in 50% BCS produced the lowest wear factor and rate for the five wear couple systems containing the carbide disk or plate material. Greater wear was produced in serum without penicillin/streptomycin (P/S) compared to the serum containing P/S. A greater carbide coating thickness 10 (micrometers) was produced during the 4hr deposition time than for the 2hr deposition (˜3mum). The nano-hardness value was higher than the micro-hardness for both the 4hr and 2hr carbide surfaces. The micro-hardness results of the worn carbide surfaces showed that an increase in BCS concentration from 0% to 100% increased the micro-hardness (HV) for carbide

Water-mediated solid-state transformation of a polymorphic drug during aqueous-based drug-layer coating of pellets.

PubMed

Lust, Andres; Lakio, Satu; Vintsevits, Julia; Kozlova, Jekaterina; Veski, Peep; Heinämäki, Jyrki; Kogermann, Karin

2013-11-01

During aqueous drug-layer coating, drug substance(s) are exposed to water and elevated temperatures which can lead to water-mediated process induced transformations (PITs). The effects of aqueous drug-layer coating of pellets (Cellets(®)) on the anhydrous piroxicam, PRX, were investigated in the miniaturized coating equipment and with free films. Hydroxypropyl methylcellulose (HPMC) was used as a carrier coating polymer. Free films were prepared by using an in-house small-scale rotating plate system equipped with an atomization air nozzle. Raman spectroscopy, X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were used to characterize the solid-state properties and surface morphology of the pellets and free films. The results showed that anhydrous PRX form I (AH) and monohydrate (MH) were stable during drug-layer coating, but amorphous PRX in solid dispersion (SD) crystallized as MH already after 10 min of coating. Furthermore, the increase in a dissolution rate was achieved from the drug-layer coated inert pellets compared to powder forms. In conclusion, water-mediated solid-state PITs of amorphous PRX is evident during aqueous-based drug-layer coating of pellets, and solid-state change can be verified using Raman spectroscopy. Copyright © 2013 Elsevier B.V. All rights reserved.

On-line surveillance of lubricants in bearings by means of surface acoustic waves.

PubMed

Lindner, Gerhard; Schmitt, Martin; Schubert, Josephine; Krempel, Sandro; Faustmann, Hendrik

2010-01-01

The acoustic wave propagation in bearings filled with lubricants and driven by pulsed excitation of surface acoustic waves has been investigated with respect to the presence and the distribution of different lubricants. Experimental setups, which are based on the mode conversion between surface acoustic waves and compression waves at the interface between a solid substrate of the bearing and a lubricant are described. The results of preliminary measurements at linear friction bearings, rotation ball bearings and axial cylinder roller bearings are presented.

Particle Engineering Via Mechanical Dry Coating in the Design of Pharmaceutical Solid Dosage Forms.

PubMed

Qu, Li; Morton, David A V; Zhou, Qi Tony

2015-01-01

Cohesive powders are problematic in the manufacturing of pharmaceutical solid dosage forms because they exhibit poor flowability, fluidization and aerosolization. These undesirable bulk properties of cohesive powders represent a fundamental challenge in the design of efficient pharmaceutical manufacturing processes. Recently, mechanical dry coating has attracted increasing attention as it can improve the bulk properties of cohesive powders in a cheaper, simpler, safer and more environment-friendly way than the existing solvent-based counterparts. In this review, mechanical dry coating techniques are outlined and their potential applications in formulation and manufacturing of pharmaceutical solid dosage forms are discussed. Reported data from the literature have shown that mechanical dry coating holds promise for the design of superior pharmaceutical solid formulations or manufacturing processes by engineering the interfaces of cohesive powders in an efficient and economical way.

Double hollow MoS2 nano-spheres: Synthesis, tribological properties, and functional conversion from lubrication to photocatalysis

NASA Astrophysics Data System (ADS)

Liu, Yueru; Hu, Kunhong; Hu, Enzhu; Guo, Jianhua; Han, Chengliang; Hu, Xianguo

2017-01-01

Molybdenum disulfide (MoS2) has extensive applications in industries as solid lubricants and catalysts. To improve the lubricating performance of MoS2, novel double-hollow-sphere MoS2 (DHSM) nanoparticles with an average diameter of approximately 90 nm were synthesized on sericite mica (SM). When the DHSM/SM composite was used as an additive in polyalphaolefin oil, friction and wear decreased by 22.4% and 63.5% respectively. The low friction and wear were attributed to the easy exfoliation of DHSM. The DHSM/SM composite was then rubbed under 40 MPa for 1 h to investigate the exfoliation and functional conversion behaviors of DHSM. Results showed that DHSM (lubricating structure) on SM could be completely exfoliated into nanosheets (catalytic structure) by rubbing. The nanosheets exfoliated from DHSM presented good photocatalytic activity for the removal of organic compounds from waste water. This work provided both a novel solid lubricant for industrial applications and a possible approach to designing a novel green lubricant for use as a photocatalyst in organic-waste treatment after lubricating service life.

Elevated Temperature Solid Particle Erosion Performance of Plasma-Sprayed Co-based Composite Coatings with Additions of Al2O3 and CeO2

NASA Astrophysics Data System (ADS)

Nithin, H. S.; Desai, Vijay; Ramesh, M. R.

2017-11-01

In this paper, investigation into solid particle erosion behavior of atmospheric plasma-sprayed composite coating of CoCrAlY reinforced with Al2O3 and CeO2 oxides on Superni 76 at elevated temperature of 600 °C is presented. Alumina particles are used as erodent at two impact angles of 30° and 90°. The microstructure, porosity, hardness, toughness and adhesion properties of the as-sprayed coatings are studied. The effects of temperature and phase transformation in the coatings during erosion process are analyzed using XRD and EDS techniques. Optical profilometer is used for accurate elucidation of erosion volume loss. CoCrAlY/CeO2 coating showed better erosion resistance with a volume loss of about 50% of what was observed in case of CoCrAlY/Al2O3/YSZ coating. Lower erosion loss is observed at 90° as compared to 30° impact angle. The erosion mechanism evaluated using SEM micrograph revealed that the coatings experienced ductile fracture exhibiting severe deformation with unusual oxide cracks. Reinforced metal oxides provide shielding effect for erodent impact, enabling better erosion resistance. The oxidation of the coating due to high-temperature exposure reforms erosion process into oxidation-modified erosion process.

Liposomes as lubricants: beyond drug delivery.

PubMed

Goldberg, Ronit; Klein, Jacob

2012-05-01

In this paper we review recent work (Goldberg et al., 2011a,b) on a new use for phosphatidylcholine liposomes: as ultra-efficient boundary lubricants at up to the highest physiological pressures. Using a surface force balance, we have measured the normal and shear interactions as a function of surface separation between layers of hydrogenated soy phophatidylcholine (HSPC) small unilamellar vesicles (SUVs) adsorbed from dispersion, at both pure water and physiologically high salt concentrations of 0.15 M NaNO(3). Cryo-Scanning Electron Microscopy shows each surface to be coated by a close-packed HSPC-SUV layer with an over-layer of liposomes on top. The shear forces reveal strikingly low friction coefficients down to 2×10(-5) in pure water system or 6×10(-4) in the 150 mM salt system, up to contact pressures of at least 12 MPa (pure water) or 6 MPa (high salt), comparable with those in the major joints. This low friction is attributed to the hydration lubrication mechanism arising from rubbing of the highly hydrated phosphocholine-headgroup layers exposed at the outer surface of each liposome, and provides support for the conjecture that phospholipids may play a significant role in biological lubrication. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Dry Lubricant Smooths the Way for Space Travel, Industry

NASA Technical Reports Server (NTRS)

2015-01-01

Reviving industry standards for coating parts in tungsten disulfide, a dry lubricant developed for the Mariner space probes managed by the Jet Propulsion Laboratory in the 1960s and '70s, Applied Tungstenite, a relatively new Temecula, California-based company, has found a client base in the mushrooming commercial space industry, as well as other manufacturers.

Optimising sulfuric acid hard coat anodising for an Al-Mg-Si wrought aluminium alloy

NASA Astrophysics Data System (ADS)

Bartolo, N.; Sinagra, E.; Mallia, B.

2014-06-01

This research evaluates the effects of sulfuric acid hard coat anodising parameters, such as acid concentration, electrolyte temperature, current density and time, on the hardness and thickness of the resultant anodised layers. A small scale anodising facility was designed and set up to enable experimental investigation of the anodising parameters. An experimental design using the Taguchi method to optimise the parameters within an established operating window was performed. Qualitative and quantitative methods of characterisation of the resultant anodised layers were carried out. The anodised layer's thickness, and morphology were determined using a light optical microscope (LOM) and field emission gun scanning electron microscope (FEG-SEM). Hardness measurements were carried out using a nano hardness tester. Correlations between the various anodising parameters and their effect on the hardness and thickness of the anodised layers were established. Careful evaluation of these effects enabled optimum parameters to be determined using the Taguchi method, which were verified experimentally. Anodised layers having hardness varying between 2.4-5.2 GPa and a thickness of between 20-80 μm were produced. The Taguchi method was shown to be applicable to anodising. This finding could facilitate on-going and future research and development of anodising, which is attracting remarkable academic and industrial interest.

Definition and effect of chemical properties of surfaces in friction, wear, and lubrication

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1978-01-01

Chemical properties relative to their role in adhesion, friction, wear and lubrication discussed in this paper will include: (1) adsorption, both physical and chemical; (2) orientation of the solid as well as the lubricant; (3) surface energy; (4) surface segregation; (5) surface versus bulk metallurgical effects; (6) electronic nature of the surface; and (7) bonding mechanisms.

Experimental research results of solid particle erosion resistance of blade steel with protective coating

NASA Astrophysics Data System (ADS)

Kachalin, G. V.; Mednikov, A. F.; Tkhabisimov, A. B.; Seleznev, L. I.

2017-11-01

The paper presents the results of metallographic studies and solid particle erosion tests of uncoated blade steel 20kH13 samples and samples with a protective coating based on chromium carbide (Cr-CrC) at a flow (air) velocity CA = 180 m/s, flow temperature tA = 25 °C, attack angle α = 30° and consumption of solid abrasive particles GP = 5·10-4 kg/s. It was found that the coating has a granular structure, a thickness is about 11 μm, the microhardness of the surface is 1520 ± 50 HV0.05. Processing of the obtained data by statistical analysis methods showed that the protective coating based on Cr-CrC increases the solid particle erosion resistance of the blade steel 20kH13 by the incubation-transitional period duration more than 2.5 times.

Lateral gradients of phases, residual stress and hardness in a laser heated Ti0.52Al0.48N coating on hard metal

PubMed Central

Bartosik, M.; Daniel, R.; Zhang, Z.; Deluca, M.; Ecker, W.; Stefenelli, M.; Klaus, M.; Genzel, C.; Mitterer, C.; Keckes, J.

2012-01-01

The influence of a local thermal treatment on the properties of Ti–Al–N coatings is not understood. In the present work, a Ti0.52Al0.48N coating on a WC–Co substrate was heated with a diode laser up to 900 °C for 30 s and radially symmetric lateral gradients of phases, residual stress and hardness were characterized ex-situ using position-resolved synchrotron X-ray diffraction, Raman spectroscopy, transmission electron microscopy and nanoindentation. The results reveal (i) a residual stress relaxation at the edge of the irradiated area and (ii) a compressive stress increase of few GPa in the irradiated area center due to the Ti–Al–N decomposition, in particular due to the formation of small wurtzite (w) AlN domains. The coating hardness increased from 35 to 47 GPa towards the center of the heated spot. In the underlying heated substrate, a residual stress change from about − 200 to 500 MPa down to a depth of 6 μm is observed. Complementary, in-situ high-temperature X-ray diffraction analysis of stresses in a homogeneously heated Ti0.52Al0.48N coating on a WC–Co substrate was performed in the range of 25–1003 °C. The in-situ experiment revealed the origin of the observed thermally-activated residual stress oscillation across the laser heated spot. Finally, it is demonstrated that the coupling of laser heating to produce lateral thermal gradients and position-resolved experimental techniques opens the possibility to perform fast screening of structure–property relationships in complex materials. PMID:23471140

Surface protection of austenitic steels by carbon nanotube coatings

NASA Astrophysics Data System (ADS)

MacLucas, T.; Schütz, S.; Suarez, S.; Mücklich, F.

2018-03-01

In the present study, surface protection properties of multiwall carbon nanotubes (CNTs) deposited on polished austenitic stainless steel are evaluated. Electrophoretic deposition is used as a coating technique. Contact angle measurements reveal hydrophilic as well as hydrophobic wetting characteristics of the carbon nanotube coating depending on the additive used for the deposition. Tribological properties of carbon nanotube coatings on steel substrate are determined with a ball-on-disc tribometer. Effective lubrication can be achieved by adding magnesium nitrate as an additive due to the formation of a holding layer detaining CNTs in the contact area. Furthermore, wear track analysis reveals minimal wear on the coated substrate as well as carbon residues providing lubrication. Energy dispersive x-ray spectroscopy is used to qualitatively analyse the elemental composition of the coating and the underlying substrate. The results explain the observed wetting characteristics of each coating. Finally, merely minimal oxidation is detected on the CNT-coated substrate as opposed to the uncoated sample.

Lubricant-Induced Crystallization of Itraconazole From Tablets Made of Electrospun Amorphous Solid Dispersion.

PubMed

Démuth, Balázs; Farkas, Attila; Balogh, Attila; Bartosiewicz, Karolina; Kállai-Szabó, Barnabás; Bertels, Johny; Vigh, Tamás; Mensch, Jurgen; Verreck, Geert; Van Assche, Ivo; Marosi, György; Nagy, Zsombor K

2016-09-01

Investigation of downstream processing of nanofibrous amorphous solid dispersions to generate tablet formulation is in a quite early phase. Development of high speed electrospinning opened up the possibility to study tableting of electrospun solid dispersions (containing polyvinylpyrrolidone-vinyl acetate and itraconazole [ITR] in this case). This work was conducted to investigate the influence of excipients on dissolution properties and the feasibility of scaled-up rotary press tableting. The dissolution rates from tablets proved to be mainly composition dependent. Magnesium stearate acted as a nucleation promoting agent (providing an active hydrophobic environment for crystallization of ITR) hindering the total dissolution of ITR. This crystallization process proved to be temperature dependent as well. However, the extent of dissolution of more than 95% was realizable when a less hydrophobic lubricant, sodium stearyl fumarate (soluble in the medium), was applied. Magnesium stearate induced crystallization even if it was put in the dissolution medium next to proper tablets. After optimization of the composition, scaled-up tableting on a rotary press was carried out. Appropriate dissolution of ITR from tablets was maintained for 3 months at 25°C/60% relative humidity. HPLC measurements confirmed that ITR was chemically stable both in the course of downstream processing and storage. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Self-lubricating layer consist of polytetrafluoroethylene micropowders and fluorocarbon acrylate resin formation on surface of geotextile

NASA Astrophysics Data System (ADS)

Long, Xiaoyun; He, Lifen; Zhang, Yan; Ge, Mingqiao

2018-04-01

In this study, the self-lubricating layer consist of polytetrafluoroethylene (PTFE) micropowders and two types fluorocarbon acrylate resin were formed on the surface of geotextile, to improves the evenness and decreases the frictional angle value of geotextile surface. The surface and cross section morphology of geotextile were examined by scanning electron microscopy (SEM). It was determined that composite resin emulsion was evenly coated on the surface of geotextile, to form a even and complete self-lubricating layer, and it was strongly combined with the geotextile due to formation of the transition layer. The tensile fracture stress and strain values of samples were evaluated by mechanical properties measurement, the tensile fracture stress of the untreated and treated sample was approximately 5329 kN/m and 5452 kN/m while the elongation at the yield of them was approximately 85% to 83.9%, respectively. In addition, the frictional angle values of municipal solid waste (MSW)/geotextile interface was measured by the tilt table test, the values of untreated sample was 28.1° and 24.2° under the dry and moist condition, the values of treated sample was 16.2° and 9.8°, respectively.

Lubrication of space systems: Challenges and potential solutions

NASA Technical Reports Server (NTRS)

Fusaro, Robert L.

1992-01-01

Future space missions will all require advanced mechanical moving components which will require wear protection and lubrication. The tribology practices used today are primarily based upon a technology base that is more than 20 years old. This paper will discuss NASA's future space missions and some of the mechanism tribology challenges that will be encountered. Potential solutions to these challenges using coatings technology will be assessed.

40 CFR 721.10636 - Slimes and sludges, automotive coating, wastewater treatment, solid waste.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., wastewater treatment, solid waste. 721.10636 Section 721.10636 Protection of Environment ENVIRONMENTAL..., wastewater treatment, solid waste. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as slimes and sludges, automotive coating, wastewater treatment...

40 CFR 721.10636 - Slimes and sludges, automotive coating, wastewater treatment, solid waste.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., wastewater treatment, solid waste. 721.10636 Section 721.10636 Protection of Environment ENVIRONMENTAL..., wastewater treatment, solid waste. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as slimes and sludges, automotive coating, wastewater treatment...

Feasibility Study of Vapor-Mist Phase Reaction Lubrication Using a Thioether Liquid

NASA Technical Reports Server (NTRS)

Morales, Wilfredo; Handschuh, Robert F.; Krantz, Timothy L.

2007-01-01

A primary technology barrier preventing the operation of gas turbine engines and aircraft gearboxes at higher temperatures is the inability of currently used liquid lubricants to survive at the desired operating conditions over an extended time period. Current state-of-the-art organic liquid lubricants rapidly degrade at temperatures above 300 C; hence, another form of lubrication is necessary. Vapor or mist phase reaction lubrication is a unique, alternative technology for high temperature lubrication. The majority of past studies have employed a liquid phosphate ester that was vaporized or misted, and delivered to bearings or gears where the phosphate ester reacted with the metal surfaces generating a solid lubricious film. This method resulted in acceptable operating temperatures suggesting some good lubrication properties, but the continuous reaction between the phosphate ester and the iron surfaces led to wear rates unacceptable for gas turbine engine or aircraft gearbox applications. In this study, an alternative non-phosphate liquid was used to mist phase lubricate a spur gearbox rig operating at 10,000 rpm under highly loaded conditions. After 21 million shaft revolutions of operation the gears exhibited only minor wear.

Evaluation of outer race tilt and lubrication on ball wear and SSME bearing life reductions

NASA Technical Reports Server (NTRS)

Kannel, J. W.; Merriman, T. L.; Stockwell, R. D.; Dufrane, K. F.

1983-01-01

Several aspects of the SSME bearing operation were evaluated. The possibility of elastohydrodynamics (EHD) lubrication with a cryogenic fluid was analyzed. Films as thick as .61 microns were predicted with one theory which may be thick enough to provide hydrodynamic support. The film formation, however, is heavily dependent on good surface finish and a low bulk bearing temperature. Bearing dynamics to determine if the radial stiffness of a bearing which are dependent on bearing misalignment were analyzed. Four ball tests were conducted at several environmental conditions from an LN2 bath to 426 C in air. Surface coatings and ball materials are evaluated. Severe wear and high friction are measured for all ball materials except when the balls have surface lubricant coatings.

Tribological properties of CVD diamond coated ceramic surfaces

NASA Astrophysics Data System (ADS)

Abreu, Cristiano Simoes de

Recent developments in chemical vapour deposited (CVD) diamond coatings have attracted considerable interest and a host of new applications, each more challenging than the others. This increased attention results from the fact that CVD diamond lms retain to a large extent the outstanding physical and chemical properties of natural single crystal diamond such as extreme hardness, chemical inertness and high corrosion resistance, optical transparency and high thermal conductivity. Diamond features also surprisingly low friction and high wear resistance in unlubricated sliding contacts. Moreover, as opposed to natural diamond where the friction and wear behaviour is highly dependent on crystal orientation, polycrystalline CVD diamond lms supersede the monocrystalline variety due to isotropic tribological properties and possibility of coating complex shapes. Several materials have been tested and more or less successfully used as substrates for CVD diamond coatings. Nonetheless, satisfactory adherence of diamond coatings lms is often only attainable by the use of interlayers, in order to compensate for the large interfacial thermal expansion mismatch between the coating and substrate, which represent an additional processing step and added costs. A promising route will consist in using substrate materials with a low thermal expansion mismatch relative to that of diamond and, therefore, enhanced 1m adhesion. Among these, the ceramic silicon nitride (Si3N4) arises as a serious candidate. As a general rule, available literature regarding the tribological performance of CVD diamond coated Si3N4 lms is scarce, and the few available tribological data only deals with low applied loads. That being said, the correct tribological assessment of CVD diamond coated Si3N4 lms under more realistic sliding conditions, reproducing the stresses found in applications fields such as the fluid handling and metalworking industry, as well as in emerging biotribological areas, is on the

The effect of incorporated self-lubricated BN(h) particles on the tribological properties of Ni-P/BN(h) composite coatings

NASA Astrophysics Data System (ADS)

Hsu, Chih-I.; Hou, Kung-Hsu; Ger, Ming-Der; Wang, Gao-Liang

2015-12-01

Ni-P/BN(h) composite coatings are prepared by means of the conventional electroless plating from the bath containing up to 10.0 g/l of hexagonal boron nitride particles with size 0.5 μm. The Ni-P coating is also prepared as a comparison. Cationic surfactant cetyltrimethylammonium bromide (CTAB) is used to stabilize the electrolyte, and the optimum CTAB concentration resulting in a nonagglomerated dispersion of particles is obtained using a dispersion stability analyzer. Morphology of the coatings and the effect of incorporated particles on coating structure and composition are investigated via scanning electron microscopy, field emission electron probe micro-analyzer and X-ray diffraction analysis. Hardness, roughness, friction coefficient and wear resistance of the coatings are also evaluated using Vickers microhardness tester, atomic force microscopy and ball-on disk machine. The presence of CTAB in the depositing bath has a positive effect on the surface roughness and performance of Ni-P/BN(h) composite coatings. The friction and wear tests results show that incorporation of 14.5 vol% BN(h) particles into the Ni-P coating lowers the coating friction coefficient by about 75% and the wear resistance of the Ni-P composites is approximately 10 times higher than Ni-P coating.

Transparency and damage tolerance of patternable omniphobic lubricated surfaces based on inverse colloidal monolayers

DOE PAGES

Vogel, Nicolas; Belisle, Rebecca A.; Hatton, Benjamin; ...

2013-07-31

A transparent coating that repels a wide variety of liquids, prevents staining, is capable of self-repair and is robust towards mechanical damage can have a broad technological impact, from solar cell coatings to self-cleaning optical devices. Here we employ colloidal templating to design transparent, nanoporous surface structures. A lubricant can be firmly locked into the structures and, owing to its fluidic nature, forms a defect-free, self-healing interface that eliminates the pinning of a second liquid applied to its surface, leading to efficient liquid repellency, prevention of adsorption of liquid-borne contaminants, and reduction of ice adhesion strength. We further show howmore » this method can be applied to locally pattern the repellent character of the substrate, thus opening opportunities to spatially confine any simple or complex fluids. The coating is highly defect-tolerant due to its interconnected, honeycomb wall structure, and repellency prevails after the application of strong shear forces and mechanical damage. The regularity of the coating allows us to understand and predict the stability or failure of repellency as a function of lubricant layer thickness and defect distribution based on a simple geometric model.« less

A shear localization mechanism for lubricity of amorphous carbon materials

PubMed Central

Ma, Tian-Bao; Wang, Lin-Feng; Hu, Yuan-Zhong; Li, Xin; Wang, Hui

2014-01-01

Amorphous carbon is one of the most lubricious materials known, but the mechanism is not well understood. It is counterintuitive that such a strong covalent solid could exhibit exceptional lubricity. A prevailing view is that lubricity of amorphous carbon results from chemical passivation of dangling bonds on surfaces. Here we show instead that lubricity arises from shear induced strain localization, which, instead of homogeneous deformation, dominates the shearing process. Shear localization is characterized by covalent bond reorientation, phase transformation and structural ordering preferentially in a localized region, namely tribolayer, resulting in shear weakening. We further demonstrate an anomalous pressure induced transition from stick-slip friction to continuous sliding with ultralow friction, due to gradual clustering and layering of graphitic sheets in the tribolayer. The proposed shear localization mechanism sheds light on the mechanism of superlubricity, and would enrich our understanding of lubrication mechanism of a wide variety of amorphous materials. PMID:24412998

Use of Textured Surfaces to Mitigate Sliding Friction and Wear of Lubricated and Non-Lubricated Contacts

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

Blau, Peter Julian

If properly employed, the placement of three-dimensional feature patterns, also referred to as textures, on relatively-moving, load-bearing surfaces can be beneficial to their friction and wear characteristics. For example, geometric patterns can function as lubricant supply channels or depressions in which to trap debris. They can also alter lubricant flow in a manner that produces thicker load-bearing films locally. Considering the area occupied by solid areas and spaces, textures also change the load distribution on surfaces. At least ten different attributes of textures can be specified, and their combinations offer wide latitude in surface engineering. By employing directional machining andmore » grinding procedures, texturing has been used on bearings and seals for well over a half century, and the size scales of texturing vary widely. This report summarizes past work on the texturing of load-bearing surfaces, including past research on laser surface dimpling of ceramics done at ORNL. Textured surfaces generally show most pronounced effects when they are used in conformal or nearly conformal contacts, like that in face seals. Combining textures with other forms of surface modification and lubrication methods can offer additional benefits in surface engineering for tribology. As the literature and past work at ORNL shows, texturing does not always provide benefits. Rather, the selected pattern and arrangement of features must be matched to characteristics of the proposed application, bearing materials, and lubricants.« less

Evaluation of replacement thread lubricants for red lead and graphite in mineral oil