Showing papers in "Tribology Transactions in 1974"
TL;DR: In this paper, the role of surface tension in contact lubrication is defined in terms of its effects on the rate of film replenishment and an analysis is presented using a depressed oil layer shape approximated by a deformed Hertzian point contact profile to predict the effect of upstream half-film height on the thickness of the plateau EHD film.
Abstract: Optical EHD experiments in a ball-flat rig reveal that the degree of EHD fluid film starvation increases with both rolling speed and viscosity. Lubricant film starvation in rolling contacts is attributed to the insufficiency of fluid replenishment in the rolling path in the time interval between contacts. A film replenishment model is used to compute the film rebounding rate. The role of surface tension in contact lubrication is defined in terms of its effects on the rate of film replenishment. An analysis is presented using a depressed oil layer shape approximated by a deformed Hertzian point contact profile to predict the effect of upstream half-film height on the thickness of the plateau EHD film. A graph is obtained for the plateau film thickness as a function of the speed-viscosity parameter and a new starvation parameter proportional to oil-air surface tension and rolling element spacing. The result is in agreement with measured plateau film thickness in circular contact at different speeds for a re...
191 citations
TL;DR: In this article, electron transmission micrographs and electron diffraction patterns were taken to determine the structural growth of MoS2 films at ambient and elevated temperatures (320 and 150 C) formed an irregular network of ridges.
Abstract: MoS2 films (300 to 400 A) were radio-frequency sputtered on aluminum and nickel surfaces at elevated, ambient, cold water, and liquid nitrogen temperatures. Electron transmission micrographs and electron diffraction patterns were taken to determine the structural growth. These transmission micrographs revealed that sputtered MoS2 films at ambient and elevated temperatures (320 and 150 C) formed an irregular network of ridges. The electron diffraction patterns of these films showed relatively sharp diffraction rings, indicating crystallinity. At water temperatures (∼7 C), ridge formation was extensively reduced or completely eliminated. The transmission micrographs of sputtered films at liquid nitrogen temperatures revealed a continuous featureless film. The electron diffraction patterns showed broad, diffused rings indicating an amorphous film. The transmission micrographs of a post annealed (425 C) MoS2 film sputtered at liquid nitrogen temperature revealed the tendency for ridge formation. Electron diff...
54 citations
TL;DR: In this paper, the steady-state thermohydrodynamic behavior of sector-shaped thrust bearings is solved numerically for an incompressible laminar flow of a Newtonian lubricant.
Abstract: Equations governing the steady-state thermohydrodynamic behavior of sector-shaped thrust bearings are solved numerically for an incompressible laminar flow of a Newtonian lubricant. The lubricant viscosity is taken as a function of the three-dimensional temperature distribution in the fluid film. Also, a general film thickness profile is allowed. Three dimensional heat transfer between the lubricant and both the moving and stationary solids is included in the analysis. The full thermohydrodynamic solutions are compared with other simpler solutions. It is shown that a type of adiabatic solution allowing for temperature gradients across the film can be used in most cases to predict accurately bearing load, friction, and lubricant flow. The results, expressed in nondimensional terms, can be applied to a wide range of operating conditions.
48 citations
TL;DR: A series of very simple radioactive chemical tests has been carried out to measure reaction of dibenzyl disulfide on steel as mentioned in this paper, and some of the requirements of extreme pressure lubrication have been determined.
Abstract: A series of very simple radioactive chemical tests has been carried out to measure reaction of dibenzyl disulfide on steel. By comparing the results with friction experiments under the same conditions, some of the requirements of extreme pressure lubrication have been determined. Current views on the mechanism of reactions of dibenzyl disulfide have been confirmed and it has been demonstrated that only a thin EP film is needed to give boundary lubrication. In particular, an important additive interference effect has been noted between extreme pressure activity and high temperature detergents. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Atlanta, Georgia, October 16–18, 1973
44 citations
TL;DR: In this article, the hypothesis that scuffing of surfaces lubricated by a plain mineral oil results from desorption is tested for high speed cases using two types of apparatus.
Abstract: The hypothesis that scuffing of surfaces lubricated by a plain mineral oil results from desorption is tested for high speed cases using two types of apparatus. One uses a medium speed, 1-inch steel ball, 4-ball machine, and a simulated oil consisting of hexadecanoic acid in hexadecane. This lubricant is shown to behave in the same fashion at medium speeds as it does at very slow speeds. Thus, a graph of logarithmic concentration of acid against reciprocal absolute scuffing temperature gives a good straight line, just as at slow speeds. In the second high speed gear tester, the rise in scuff load of gears at very high speeds, the Borsoff effect, can be explained semiquantitatively by considering the residence time of molecules. These two types of results suggest that the desorption-failure mechanism may be valid over the whole rubbing speed range, and not merely at the very low speeds normally tested. Presented at the 28th ASLE Annual Meeting in Chicago, Illinois, April 30–May 3, 1973
41 citations
TL;DR: In this article, Czichos et al. used general systems theory (GST) and applied it to tribo-testing in the laboratory as well as that of technical machinery.
Abstract: The great variety of topics covered by the term tribology needs some guiding principles. These are provided by general systems theory (GST), more in particular a scale of reference proposed by Boulding. Logical analysis of certain technical terms (Popper, Polanyi, Von Neumann) permits a systems classification of tribological concepts. The origin of discrepancies between the scientific and the engineering approach to friction can now be traced. Conventional engineering system analysis (ESA) is restricted to macrodynamical systems; it yields no information on elementary friction and wear processes. Czichos in the companion paper (1) has extended the scope of ESA to tribology. The combined use of GST and ESA should, in future, influence the design of tribo-testing in the laboratory as well as that of tribo-technical machinery. Presented at the 3rd Meeting of the International Research Group (IRG) on Wear of Engineering Materials held in London, July 16–18, 1973. Contributed by the author to ASLE in October, ...
34 citations
TL;DR: A general approach on the application of systems thinking to tribology is presented in the preceding article by G. Salomon as mentioned in this paper, and this formalizm is applied to tribological objects.
Abstract: Tribology is an interdisciplinary subject which is connected to parts of mechanical engineering, materials science, physics, chemistry, and other branches of science and technology. Therefore, in research, design, development, and application of tribological objects interdisciplinary superior principles are needed. Such principles may be found using the methods of general systems theory and engineering systems analysis. A general approach on the application of systems thinking to tribology is presented in the preceding article by G. Salomon. In this paper, first the mathematical methods of system analysis are described. Then, this formalizm is applied to tribological objects. Finally, the advantages of the system-analytical approach to tribology are summarized. Presented at the 3rd Meeting of the International Research Group (IRG) on Wear of Engineering Materials held in London, July 16–18, 1973. Contributed by the author to ASLE in September, 1973.
31 citations
TL;DR: In this paper, the effects of contact pressure and temperature on the shear strength of thin organic films were investigated and compared with the bulk shear properties and consideration has been given to the molecular processes occurring during shear.
Abstract: This paper deals with the effects of contact pressure and temperature on the shear strength of thin organic films. The experimental method involves depositing the material as thin films (ca. 3 nm to 500 nm) on smooth glass surfaces. The film is sheared by sliding over it indenters of fired glass. By varying the indenter radius from 4 μm to 2.5 mm and the load from 10 mg to 20 g, the contact pressure may be varied from 107 Pa (1.4 × 103 P.s.i.) to 8 × 109 Pa (12 × 105 p.s.i.). The temperature dependence of the shear strength is also studied. Two types of organic materials have been investigated. These range from simple low molecular weight compounds such as stearates, to more complex high molecular weight polymers, for example P.M.M.A. The shear strength of these films has been compared with the bulk shear properties and consideration has been given to the molecular processes occurring during shear. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held...
29 citations
TL;DR: In this article, the authors measured friction and wear during sliding of specimens of Nimonic 75, C263, Nimonic 108 and Incoloy 901 in air at temperatures from 20 to 800 C.
Abstract: Measurements of friction and wear during sliding of specimens of Nimonic 75, C263, Nimonic 108 and Incoloy 901 on like specimens in air at temperatures from 20 to 800 C are presented. Under the sliding conditions used, all the alloys show a transition temperature, above which low wear and a low coefficient of friction during sliding are observed after a time and below which these parameters remain relatively high throughout. These temperatures are about 150 C for N75, about 200 C for C263 and N108 and between 200 and 300 for Incoloy 901. At given temperatures above the transition temperatures, the coefficient of friction-time loci show sharp, generally very reproducible, changes from relatively high to low coefficients of friction. The times at which these occur decrease with increasing temperature for a given alloy. Such changes can be closely correlated to the formation of a stable, adherent, thermally softened, oxide layer or glaze on the load-bearing areas during sliding. Once the glaze is established...
28 citations
TL;DR: In this paper, a hemispherical rider sliding on a rotating disk was used to study the chemical interactions of oxygen and sulfur with iron when surfaces are stationary and also during sliding in a vacuum environment.
Abstract: A a investigation was conducted to determine the nature of the chemical interactions of oxygen and sulfur with iron when surfaces are stationary and also during sliding in a vacuum environment. Various gases that contained sulfur, oxygen, or both were adsorbed to iron al 23 C. The gases included oxygen, hydrogen sulfide, methyl mercaptan, and sulfur dioxide. Friction experiments were conducted with a hemispherical rider sliding on a rotating disk. An Auger cylindrical mirror analyzer was used to monitor the iron surface chemistry. The results of this study indicate that oxygen will completely displace sulfide films from iron surfaces. Organic thiols containing sulfur, such as methyl mercaptan, adsorb to an iron surface dissociatively. Only sulfur is detected on the iron surface. Sliding inhibits the formation of sulfide films on iron with the adsorption of hydrogen sulfide and methyl mercaptan. With oxygen and sulfur dioxide, the sliding process does not effect adsorption behavior. Presented as an America...
28 citations
TL;DR: In this article, a nichrome matrix containing dispersed glass for oxidation protection and calcium fluoride for lubrication is applied to bearing surfaces by plasma spraying layers about 0.050 cm thick which are then machined to 0.025 cm.
Abstract: Plasma-sprayed composites, which have good oxidation resistance and self-lubricating characteristics to 900 C, were developed. The composites are a nichrome matrix containing dispersed glass for oxidation protection and calcium fluoride for lubrication; they are applied to bearing surfaces by plasma spraying layers about 0.050 cm thick which are then machined to 0.025 cm. Oscillating bearing tests were performed in air to 900 C at unit radial loads up to 5000 psi and a thrust load of 440 lb. Bearings with a composite liner in the bore were in good condition after over 50,000 oscillating cycles accumulated during repeated bearing temperature cycles between 25 and 900 C.
TL;DR: In this article, the hydrodynamic theory of lubrication for dynamically loaded journal bearings is extended to elastico-viscous lubricants, with the second-order terms representing cross-stresses and stress relaxation.
Abstract: The hydrodynamic theory of lubrication for dynamically loaded journal bearings is extended to elastico-viscous lubricants. The Rivlin-Ericksen equation is assumed for the lubricant, with the second-order terms representing cross-stresses and stress relaxation. The orbits of the journal center deviating from its static equilibrium position were calculated for constant and periodic load conditions. A considerable improvement, compared with the Newtonian solution, is obtained. This is evident from the diminished eccentricity of the orbits and the faster damping of disturbances.
TL;DR: A burnished film of graphite fluoride was used to lubricate a sphere-on-plane test configuration as mentioned in this paper, and the rate of volume worn was approximately constant after the first two minutes.
Abstract: A burnished film of graphite fluoride was used to lubricate a sphere-on-plane test configuration. Compressive stress and sphere wear volume were determined as functions of time from the wear scar area on the sphere. The stress variation was extreme, from 122,000 psi initial value to a final value of 796 psi after 376.2 min of rubbing. The rate of volume worn was approximately constant after the first two minutes. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Atlanta, Georgia, October 16–18, 1973
TL;DR: In this paper, the dynamic response of a gas-lubricated, jet-engine main shaft seal was analytically established as a function of collar misalignment and secondary seal friction.
Abstract: Dynamic response of a gas-lubricated, jet-engine main shaft seal was analytically established as a function of collar misalignment and secondary seal friction. Response was obtained by a forward integration-in-time (time-transient) scheme, which traces a time history of seal motions in all its degrees of freedom. Results were summarized in the form of a seal tracking map which indicated regions of acceptable collar misalignments and secondary seal friction. Methodology, results and interpretations are comprehensively described.
TL;DR: In this paper, the finite element method is applied to the incompressible lubrication problem and the finite slider bearing profile is sought which maximizes the load carrying capacity for a given minimum film thickness.
Abstract: The finite slider bearing profile is sought which maximizes the load carrying capacity for a given minimum film thickness. Several suboptimization problems in the “space” of stepped profiles are considered. The efficient application of the finite element method to the incompressible lubrication problem is outlined.
TL;DR: In this paper, the behavior of mineral oils under high hydrostatic pressure was studied and it was found that a test oil converts from a liquid to a solid faster than within 9 μs when the time mean value of the pressure is 1,200 N/mm2 (12,000 atmospheres).
Abstract: The behavior of mineral oils under high hydrostatic pressures is studied. It is found that a test oil converts from a liquid to a solid faster than within 9 μs when the time mean value of the pressure is 1,200 N/mm2 (— 12,000 atmospheres). As the solidification velocity for liquids increases approximately proportional to the pressure rise above the static solidification pressure, this solidification time shows that rolling element bearings under normal working conditions have solidified oil in the high pressure part of the contact.
BP1
TL;DR: In this paper, the load-carrying and adsorption/reaction properties of a range of dialkyl phosphites have been examined under antiwear and antiscuff conditions using the four-ball machine.
Abstract: The load-carrying properties of a range of dialkyl phosphites have been examined under antiwear (AW) and antiscuff conditions using the four-ball machine. Adsorption/reaction of these compounds with iron surfaces has also been carried out. The results showed that both the load-carrying and adsorption/reaction properties of these dialkyl phosphites are markedly affected by the chain length and structure of the alkyl group. A mechanism of action of dialkyl phosphites is proposed which not only provides an explanation for both sets of observations but also highlights the difference in load-carrying action of dialkyl phosphites compared to the corresponding phosphates. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Atlanta, Georgia, October 16–18, 1973
TL;DR: In this article, the authors describe the disk machine designed and constructed for the investigation of the traction in elastohydrodynamic line contacts for two synthesized hydrocarbon fluids and compare the theoretical predictions of traction according to the thermal and non-Newtonian theory recently presented by the authors.
Abstract: The paper describes the disk machine designed and constructed for the investigation of the traction in elastohydrodynamic line contacts for two synthesized hydrocarbon fluids. The results of this experimental study are presented and compared with the theoretical predictions of traction according to the thermal and non-Newtonian theory recently presented by the authors (1). Presented as on American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Atlanta, Georgia, October 16–18, 1973
TL;DR: In this paper, a simplified molecular flow effusion model is proposed, modified to account for the evaporation rate and rate of vapor pressure change of polymeric lubricating oils, which is useful for accurate predictions of long-term lubricant loss through annular-design labyrinth seals of wet-lubricated aerospace mechanisms and vacuum chamber components.
Abstract: High-vacuum naphthalene evaporation loss experiments were conducted with a specially designed annular effusion cell to examine the validity of the most frequently used theoretical models of molecular flow, specifically applied to a high molecular weight organic compound. Literature data are similarly correlated to (a) show the respective accuracy of the various formulae and (b) discuss the most prevalent effusion experimental errors often causing orders of magnitude differences between theoretical predictions and experimental results. A simplified molecular flow effusion model is proposed, modified to account for the evaporation rate and rate of vapor pressure change of polymeric lubricating oils. The results and conclusions are useful for accurate predictions of long-term lubricant loss through annular-design labyrinth seals of wet-lubricated aerospace mechanisms and vacuum chamber components. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in ...
TL;DR: In this paper, sliding friction studies were conducted on an iron surface with exposure of that surface to various hydrocarbons and organic chlorides, including ethane, ethylene, ethyl chloride, methyl chloride and vinyl chloride.
Abstract: Sliding friction studies were conducted on an iron surface with exposure of that surface to various hydrocarbons and organic chlorides. The hydrocarbons included ethane, ethylene, ethyl chloride, methyl chloride and vinyl chloride. Auger cylindrical-mirror analysis was used to follow interactions of the hydrocarbon and organic chlorides with the iron surface. Results with vinyl chloride indicate friction-induced surface reactivity, adsorption to surface oxides, friction sensitivity to concentration and polymerization. Variation in the loads employed influence adsorption and, accordingly, friction. Unlike results with ethyl and vinyl chloride, friction-induced surface reactivity was not observed with ethane and ethylene. Presented at the 28th ASLE Annual Meeting in Chicago, Illinoir, April 30–May 3, 1973
TL;DR: In this paper, an analytical and experimental work was presented to determine the nature of the coefficient of friction at the large rib roller end of a tapered roller bearing, and it was shown that for normal bearing speeds the inertial forces have negligible effect on the performance at the rib contact.
Abstract: Analytical and experimental work is presented to determine the nature of the coefficient of friction at the large rib roller end of a tapered roller bearing. The analytical work considers the dynamic equilibrium of a roller, and it is shown that for normal bearing speeds the inertial forces have negligible effect on the performance at the rib contact. Mathematical expressions for the frictional torque on a detached rib have been derived for the case of axially applied bearing loads. Experimental work has been carried out to obtain the rib torque values for the detached rib of a tapered roller bearing. Experimental information has been presented to show the variation in the value of the coefficient of friction with the sliding speed and the Hertzian stress at the rib contact. It is observed that the condition of lubrication is an important factor influencing the performance at the rib and that for the hydrodynamic condition of lubrication, the value of the rib torque is very low. Presented at the 28th ASLE...
TL;DR: In this article, the authors investigated the load factor for gas film sealing under subsonic and choked flow conditions, laminar and turbulent flows, and various seal entrance conditions, and the importance of generating hydrodynamic forces to keep the seal balanced under severe and multipoint operation.
Abstract: Proper pressure balancing of gas film seals requires knowledge of the pressure profile load factor (load factor) values for a given set of design conditions In this study, the load factor is investigated for subsonic and choked flow conditions, laminar and turbulent flows, and various seal entrance conditions Both parallel sealing surfaces and surfaces with small linear deformation were investigated The load factor for subsonic flow depends strongly on pressure ratio; under choked flow conditions, however, the load factor is found to depend more strongly on film thickness and flow entrance conditions rather than pressure ratio The importance of generating hydrodynamic forces to keep the seal balanced under severe and multipoint operation is also discussed
TL;DR: In this paper, a method is presented to accurately estimate extended temperature range evaporation rate and vapor pressure data for polymeric oils, incorporating appropriate corrections for the increases in molecular weight and the change in volatility of the progressively evaporating polymer fractions.
Abstract: A recently developed ultrahigh-vacuum quartz spring mass sorption microbalance has been utilized to measure the evaporation rates of several low-volatility polymeric lubricating oils at various temperatures. The evaporation rates are used to calculate the vapor pressures by the Langmuir equation. A method is presented to accurately estimate extended temperature range evaporation rate and vapor pressure data for polymeric oils, incorporating appropriate corrections for the increases in molecular weight and the change in volatility of the progressively evaporating polymer fractions. The logarithms of the calculated data appear to follow linear relationships within the test temperature ranges, when plotted versus 1000/T. These functions and the observed effusion characteristics of the fluids on progressive volatilization are useful in estimating evaporation rate and vapor pressure changes on evaporative depletion. Presented at the 28th ASLE Annual Meeting in Chicago, Illinois, April 30–May 3, 1973
TL;DR: In this article, a group of bearings is divided into a number of equal-sized subgroups and tested only until the first failure occurs in each subgroup, and general procedures based on maximum likelihood estimates are given for setting confidence limits on L10 life from sudden death test results.
Abstract: In sudden death testing, a group of bearings is divided into a number of equal-sized subgroups and tested only until the first failure occurs in each subgroup. General procedures based on maximum likelihood estimates are given for setting confidence limits on L10 life from sudden death test results, and the necessary tabular values are given for some sample and subgroup sizes. Comparisons are made of the total expected test time and the precision in determining L10 by (a) a sudden death test and by (b) a conventional endurance test having the same total sample size and number of failures. Presented at the 28th ASLE Annual Meeting in Chicago, Illinois, April 30–May 3, 1973
TL;DR: The friction coefficient and shear strength of thin layers of the inorganic coordination polymer {Cr[OP(C8H17)2O] [OP(CH3)(C6H5)O]2] have been measured at room temperature at pressures up to about 3.5 kbar as discussed by the authors.
Abstract: The friction coefficient and shear strength of thin layers of the inorganic coordination polymer {Cr[OP(C8H17)2O] [OP(CH3)(C6H5)O]2}x have been measured at room temperature at pressures up to about 3.5 kbars. The friction coefficient of this material is not independent of load as required by Amontons' classical law of friction, but rather, the friction coefficient decreases sharply with increasing load and approaches a small asymptotic value at high loads. This violation of Amontons' law is readily explained by a simple extension of the adhesion theory of friction in which effects of complete contact at the interface and the pressure dependence of the shear strength of the sample are taken into account. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Atlanta, Georgia, October 16–18, 1973
TL;DR: In this paper, a solution of the Reynolds equation for finite bearings with exponential film shape and variable viscosity is presented, which can be used either for plane or convergent curved surfaces with a satisfactory accuracy.
Abstract: A solution of the Reynolds equation for finite bearings with exponential film shape and variable viscosity is presented. The field of temperatures is also investigated, by solving the Energy equation. Therefore, the uncoupling of Reynolds and Energy equations is obtained, by using a relationship between viscosity and film thickness. The solution may be used either for plane or convergent curved surfaces with a satisfactory accuracy, as shown by the diagrams of pressure and temperatures. The formulas are given in closed forms, either for adiabatic films or constant temperature boundaries, thus allowing rapid calculations. Furthermore, formulas for the overall characteristics are available, which may be directly used in bearing design.
TL;DR: In this article, a study of the lubricating properties of some codeposited composites of metal-graphite fluoride platings was made and it was shown that graphite fluoride was more effective in water and oil than it was in air.
Abstract: A study has been made of lubricating properties of some codeposited composites of metal-graphite fluoride platings. Copper was found to be a better matrix of the plating than nickel, with respect to the lubricating properties. Sufficient contents of solid lubricants in matrices were necessary to improve the wear rate of composites. Graphite fluoride was a more effective lubricant in water and oil than it was in air. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Atlanta, Georgia, October 16–18, 1973
TL;DR: In this paper, a disc machine is used to demonstrate the increase in frictional traction with time until a steady-state value less than that of the carrier oil is achieved, which is associated with the mechanical degradation of the grease structure, which also results in a reduced film thickness.
Abstract: Experimental results using a disc machine are given which clearly demonstrate the increase in frictional traction with time until a steady-state value less than that of the carrier oil is achieved. This increasing traction is associated with the mechanical degradation of the grease structure, which also results in a reduced film thickness. It is also shown that greases can lead to starvation, and hence failure, at higher slip speeds, and this effect is probably associated with the viscoelastic properties of the grease. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Atlanta, Georgia, October 16–18, 1973
TL;DR: A brief history of the development of the idea that static and kinetic frictions are somehow different is presented in this paper, and the investigations which produced data promoting this idea are discussed.
Abstract: A brief history of the development of the idea that static and kinetic frictions are somehow different is presented. The investigations which produced data promoting this idea are discussed and, in...
TL;DR: In this article, self-lubricating composites have been prepared by impregnation of various porous stainless steel matrices with PbO-SiO2 95-5w/o and CaF2-BaF2 38-62w/O.
Abstract: Self-lubricating composites have been prepared by impregnation of various porous stainless steel matrices with PbO-SiO2 95–5w/o and CaF2-BaF2 38–62w/o. The composites have been tested to evaluate the influence of pore diameter on their characteristics. Lubricant properties have been evaluated in oxidizing atmosphere in the temperature range 25–650C through the rider wear and friction test. The results show that the specimens obtained through impregnation of metallic skeleton with smaller capillary diameter are the best and in the case of CaF2-BaF2 base composites their lubricant properties are also better of the lubricant in massive condition. The mechanical properties of the composite are acceptable for many applications. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Atlanta, Georgia, October 16–18, 1973