Showing papers in "Tribology Transactions in 1969"
TL;DR: Physical sputtering deposition of molybdenum disulfide films as solid lubricant on rotating and sliding components, discussing lubrication properties in vacuum as discussed by the authors, was discussed.
Abstract: Physical sputtering deposition of molybdenum disulfide films as solid lubricant on rotating and sliding components, discussing lubrication properties in vacuum
52 citations
Esso1
TL;DR: In this article, a mathematical model based on the existing theories of corrosion and wear is proposed for analyzing the controlling phenomena in corrosive wear caused by atmospheric oxygen, making the assumption that all of the wear proceeded by a corrosion mechanism, i.e., the growth of an oxide layer and subsequent removal by rubbing.
Abstract: A mathematical model based on the existing theories of corrosion and wear is proposed for analyzing the controlling phenomena in corrosive wear caused by atmospheric oxygen. The model is applied to experimental wear data, making the assumption that all of the wear proceeded by a corrosion mechanism, i.e., the growth of an oxide layer and its subsequent removal by rubbing. The analytical results show that the rate of metal oxidation is the more important factor in determining the wear rate. The proposed model, assuming oxidation to follow a parabolic rate law, predicts a much higher rate constant and a lower activation energy for oxidation in corrosive wear than in static corrosion at the same “hot spot” temperature. It is postulated that this is due to a mechanical activation phenomena caused by rubbing action. The increase of wear at higher loads can be accounted for by a simple increase in oxidation rate at a higher surface temperature. Presented as an American Society of Lubrication Engineers paper at ...
51 citations
Esso1
TL;DR: In this article, it was shown that wear in humid air is destructive, but can be entirely eliminated by blanketing the system in dry nitrogen, and that the wear effect of air is entirely reversible it occurs with most metallurgies and lubricant types.
Abstract: Oxygen and moisture are shown to cause a significant increase in friction and wear under non-scuffing conditions. In certain cases, wear in humid air is destructive, but can be entirely eliminated by blanketing the system in dry nitrogen. This pro-wear effect of air is entirely reversible it occurs with most metallurgies and lubricant types, and it may be controlled by incorporating suitable additives in the oil. Various wear mechanisms have been examined to explain the experimental results; the most satisfactory is a simple corrosive wear phenomenon, involving the formation and rubbing away of metal oxides. Presented at the ASME/ASLE Lubrication Conference, Atlantic City, New Jersey, October 8–10, 1968.
39 citations
TL;DR: In this paper, the method of predicting seal swell has been extended to include three-dimensional solubility parameter concepts, and it has been demonstrated on 975 combinations of 15 vulcanized elastomers and 133 pure liquids.
Abstract: The method of predicting seal swell previously reported by this laboratory, has been extended to include three-dimensional solubility parameter concepts. Techniques for analysis and the calculation of the partial solubility parameters in consistent dimensions have been formulated for pure liquids, binary mixtures of known composition, and multicomponent mixtures of unknown ingredients. Although the quantitative analysis of swell requires analyzing seven or more variables simultaneously, it can be represented with two dimensional graphs in the region of greatest interest to the hydraulics engineer by observing a few simple rules. With this scheme, it is possible to predict, with 97% accuracy, whether a particular fluid/elastomer combination will meet a specification limit of 25% maximum swell. This has been demonstrated on 975 combinations of 15 vulcanized elastomers and 133 pure liquids. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference held in Atlanti...
33 citations
TL;DR: In this article, the authors proposed a reaction mechanism for tricresyl phosphate (TCP) stabilizing the metal-ester system by generating a passive oxide film on the active metal surface.
Abstract: Neopentyl polyol esters, typical of turbine engine lubricant base stocks, are thermally stable at 500 F, unless, as reported by others, ferrous metals are present; in the latter case oil degradation and metal corrosion are severe. Tricresyl phosphate (TCP) stabilizes the metal-ester system by generating a passive oxide film on the active metal surface. In the presence of water, TCP accelerates ester hydrolysis, resulting in acids corrosive to lead. Aliphatic amines which react with TCP acidic impurities or breakdown products reduce the catalyzed hydrolysis of the esters. TCP reacts with free carboxylic acids to generate corrosive phosphoric-type acids. Reaction mechanisms are postulated. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Houston, Texas, October 14–16, 1969
24 citations
TL;DR: In this paper, a mathematical model of sub-surface and surface crack propagation is presented, and the life to failure of volume elements in the vicinity of a defect (defect life) is formulated.
Abstract: Variables affecting the fatigue life of a rolling contact are identified. A mathematical model of sub-surface and surface crack propagation is presented. The life to failure of volume elements in the vicinity of a defect (defect life) is formulated. A term “severity” of a microdefect has been defined. The model is characterized by the inclusion of bulk material parameters, defect characteristics and parameters of geometry, stress, lubrication and surface topography. A statistical expression for the life of an entire rolling body is based on the defect life formula. The new model comprises current standard bearing life prediction formulas as a special case. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference held in Atlantic City, New Jersey, October 8–10, 1968.
20 citations
TL;DR: In this paper, the performance of a centrally loaded liquid-lubricated 180° partial hydrodynamic journal bearing with shaft misalignment is considered, restricted to shaft tilt about an axis normal to a plane bisecting the bearing arc, as would arise from elastic deflection of the shaft under load.
Abstract: The performance of centrally loaded liquid-lubricated 180° partial hydrodynamic journal bearings with shaft misalignment is considered. Misalignment is restricted to shaft tilt about an axis normal to a plane bisecting the bearing arc, as would arise from elastic deflection of the shaft under load. The results of numerical calculations for L/D ratios of 1, ½, and ¼ and a range of tilt angles are presented in the form of nomograms, design charts and tables. The effect of misalignment on bearing performance is discussed and illustrated with sample calculations. Presented at the 24th ASLE Annual Meeting in Philadelphia, May 5–9, 1969.
20 citations
TL;DR: In this article, the effect of stiffness in the direction normal to the plane of contact between surfaces in sliding contact had on the phenomenon of stick-slip was investigated and the results showed that the amplitude if stickslip vibrations could be reduced by increasing the normal stiffness with contacting surfaces of mild steel.
Abstract: This work determined what effect stiffness in the direction normal to the plane of contact between surfaces in sliding contact had on the phenomenon of stick-slip. The results showed that the amplitude if stick-slip vibrations could be reduced by increasing the normal stiffness with contacting surfaces of mild steel. It was also observed that with the above mentioned surfaces some wear had to take place before stick-slip would occur. This was attributed to the initial presence of oxide on the surfaces. Presented at the 24th ASLE Annual Meeting in Philadelphia, May 5–9, 1969.
18 citations
TL;DR: In this paper, low-speed friction tests with fine diamond styli and spherical sliders of ruby, sapphire, and hardened steel were carried out on the crystallographically prominent planes of synthetic single-crystal rutile at room temperature.
Abstract: Low-speed friction tests with fine diamond styli and spherical sliders of ruby, sapphire, and hardened steel were carried out on the crystallographically prominent planes of synthetic single-crystal rutile at room temperature. The friction against diamond was 0.04–0.10; against sapphire and steel, 0.10–0.15. Ploughing friction was found to be anisotropic. When larger sliders were used so that the contribution by ploughing was minimized, the frictional anisotropy vanished. The anisotropy of ploughing was correlated with plastic deformation by slip in and adjacent to the friction track, as seen and studied with the optical microscope. Surface damage by cleavage and brittle failure was found to be severe during the friction experiments. Presented as an American Society of Lubrication Engineers paper of the ASME/ASLE Lubrication Conference held in Atlantic City, New Jersey, October 8–10, 1968.
17 citations
TL;DR: In this paper, the friction properties of two groups of copper-based bearing alloys, one with nominal compositions of 6% Sn, and the other with 15% Pb, were studied in argon and air as well as in various lubricants of 25 ± 1 C.
Abstract: The friction properties of two groups of copper-based bearing alloys, one with nominal compositions of 6% Sn, and 0, 5, 10, 15, 20, 25% Pb, and the other with 15% Pb and 0, 3, 6, 9, 12 and 15% Sn, were studied in argon and air as well as in various lubricants of 25 ± 1 C. Without lubrication, the presence of lead is essential in that the smeared Pb film, which is formed on the bronze surface by extrusion from the matrix, protects the steel shaft from severe damage. Up to 10%, Pb also lowers the wear of the bearing material itself appreciably. Up to 9%, Sn is beneficial. When a relatively viscous lubricant is applied, a running-in period is followed by a transition towards a fully hydrodynamic condition (f < 0.01). A “critical load” (Lc) exists, below which running-in wear is negligible and above which excessive wear occurs. Under these conditions, alloys with a coarse Pb distribution behave much better than alloys with finely divided Pb. In fine-grained alloys, addition of Pb is unfavorable as Pb lowers t...
17 citations
TL;DR: In this article, an analysis of grinding swarf combined with calculations of the kinetics of the oxidation reaction indicate that oxidation leads to increased plasticity of the metal during chip formation.
Abstract: The spark shower that is commonly observed when ferrous metals and other alloys are abraded is caused by the exothermic reaction of atmospheric oxygen with the freshly formed surfaces of the metal chips. This reaction greatly facilitates grinding as evidenced by a large increase in grinding forces when oxygen is removed from the tool-metal interface. Examination of grinding swarf combined with calculations of the kinetics of the oxidation reaction indicate that oxidation leads to increased plasticity of the metal during chip formation. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference held in Atlantic City, New Jersey, October 8–10, 1968.
TL;DR: In this article, a combination if electron photo micrographs and sensitive friction measurements indicate that the dry friction if glass may be due to surface melting under frictional heat, and the characteristic "tear drop" scratch is seen to be composed if a widening track if fused cracks ending in a "circular spot" if fused glass.
Abstract: A combination if electron photo micrographs and sensitive friction measurements indicate that the dry friction if glass may be due to surface melting under frictional heat. Stick slip phenomena are examined and the characteristic “tear drop” scratch is seen to be composed if a widening track if fused cracks ending in a “circular spot” if fused glass. Low temperatures or lubrication prevent this. For short durations at low loads, temperatures, and sliding speeds, most lubricants gave the same friction and wear results. When conditions become more severe or time more extended, various classes if lubricant excellence can be found. Wear measurements following “run in” indicate that with proper lubricants and operating conditions glass bearing surfaces can be operated at high loads and high temperatures. Presented at the 24th ASLE Annual Meeting in Philadelphia, May 5–9, 1969.
TL;DR: In this paper, the minimum gas flow rate equation for high speed polytetrafluorethylene (PFL) ball bearings operating in cold hydrogen gas was developed for high-speed PFL ball bearings.
Abstract: Cooling requirements for high speed polytetrafluorethylene lubricated ball bearings operating in cold hydrogen gas, developing minimum gas flow rate equation
TL;DR: In this article, the effects of speed, load and contact length on the coefficient of traction and relative creep between two plain cylinders lubricated with a naphthenic mineral oil were investigated.
Abstract: This paper discusses test results obtained on a single contact, cylindrical, traction test machine operating at rolling speeds ranging from 5,000 fpm to 25,000 fpm and at maximum Hertz stresses from nearly zero to 200,000 psi. Effects of speed, load and contact length on traction and relative creep between two plain cylinders lubricated with a naphthenic mineral oil were investigated. Test results indicate that coefficient of traction and creep were greatly affected by all three variables tested. Interestingly, the increase in normal load always resulted in an increase in coefficient of traction. However, beyond the contact stress of 200,000 psi, the load effect practically disappeared. No discontinuities were discovered in the coefficient of traction curves in the speed and load range tested. However, boundary lines were established separating the regions of complete hydrodynamic lubrication (where traction is nearly zero), from elasto-hydrodynamic regions (where the traction rises with load). The obtain...
TL;DR: In this paper, a parametric study is made on the single-recess rectangular pad with a wide range of pad geometry considered, and each pad geometry is combined with each of the compensation types for the complete range of static pressure ratios.
Abstract: This paper is concerned with squeeze film damping in hydrostatic pads having the various types of compensation normally used (i.e., capillary, orifice and constant-flow). A computerized analysis is used to determine bearing squeeze film pad performance with the various compensation types. A parametric study is made on the single-recess rectangular pad with a wide range of pad geometry considered. Each pad geometry is combined with each of the compensation types for the complete range of static pressure ratios. A sample problem is presented which demonstrates the use of hydrostatic squeeze film characteristics and design curves developed. Presented at the 24th ASLE Annual Meeting in Philadelphia, May 5–9, 1969.
TL;DR: Sliding friction tests of Cu and Cu-Be alloy plates in contact with various alloy sliders in air and vacuum were performed by as discussed by the authors, showing that they can be used to test the elasticity of the plates.
Abstract: Sliding friction tests of Cu and Cu-Be alloy plates in contact with various alloy sliders in air and vacuum
TL;DR: Gas lubricated tilting pad thrust bearing analysis and performance, determining optimum hydrodynamic crown profile was discussed in this article, with the goal of determining the optimal hydrodynamics of the crown.
Abstract: Gas lubricated tilting pad thrust bearing analysis and performance, determining optimum hydrodynamic crown profile
TL;DR: In this paper, the parent polyols are determined by programmed temperature gas chromatography of their valerate esters, and a semi-preparative thin-layer chromatographic method permits the isolation of the three main ester types, trimethylol propane, pentaerythritol, and dipentaerythrin.
Abstract: Because of the increasing use of the neopentyl polyol esters as lubricants, an analytical method capable of giving detailed information concerning the composition of these complex ester mixtures is desirable. Methods of gas-liquid chromatography and thin-layer chromatography have been applied in the successful development if such an analytical method. By direct programmed temperature gas chromatography of the lubricants, the components are separated according to volatility; in most cases resolution is adequate for semi-quantitative analysis. Gas-liquid chromatographic analysis of the free acids produced by hydrolysis of the sample reveals the acyl composition. The parent polyols are determined by programmed temperature gas chromatography of their valerate esters. A semi-preparative thin-layer chromatographic method permits the isolation of the three main ester types, trimethylol propane, pentaerythritol, and dipentaerythritol, for further analysis. A combination of these analytical methods permits a detai...
TL;DR: In this article, the wear and friction properties of three representative neopentyl polyol esters, together with the common diester lubricant base, bis(2-ethylhexyl) sebacate, were studied with the four-ball wear machine at 266 F and 5-50 kg load in the presence and in the absence if tricresyl phosphate.
Abstract: Wear and friction properties of three representative neopentyl polyol esters, together with the common diester lubricant base, bis(2-ethylhexyl) sebacate, were studied with the four-ball wear machine at 266 F and 5–50 kg load in the presence and in the absence if tricresyl phosphate. The rubbing surfaces were 52100 steel, 440 C stainless steel and M-50 steel. With 52100 low-chromium steel balls, wear rates were largely independent of ester type. Percolated tricresyl phosphate reduced wear moderately at low loads only. Stainless steel 440 C and M-50 steel gave results significantly different from those with 52100 steel at all loads. In the case of the stainless steel wear was greatly increased at a load of 50 kg and tricresyl phosphate (1%) was ineffective at all loads. M-50 steel gave the lowest wear rates. It showed no response to tricresyl phosphate. Average friction coefficients of all the steels showed little change with the variables examined except for a small increase with load and for slightly low...
Esso1
TL;DR: In this paper, a method for obtaining vapor pressure over the temperature range of interest in engine lubrication (300-500 F) is presented based on the saturation efficiency of an air stream and the relationship between vapor pressure and evaporation loss.
Abstract: A method is presented for obtaining vapor pressures over the temperature range of interest in engine lubrication (300–500 F). The determination is based on the saturation efficiency of an air stream and the relationship between vapor pressure and evaporation loss. All data required are readily obtained from the ASTM Evaporation Test Method D 972-56 which is already used in connection with the evaporation loss specification of turbo oils. In addition to vapor pressure, the method is also used to estimate the flash point of these same lubricants. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference held in Atlantic City, New Jersey, October 8–10, 1968.
TL;DR: In this paper, various factors that determine the stability and separation rate of oil from oily water mixtures are reviewed, including droplet size, viscosity and unique interfacial properties promoted by the presence of surface active agents.
Abstract: The various factors that determine the stability and separation rate of oil from oily water mixtures are reviewed. The effect of droplet size, viscosity and unique interfacial properties promoted by the presence of surface-active agents are considered. The appropriate means to handle the separation/removal of oil from waste water effluents, as influenced by these factors, will be discussed. Wherever possible, first principles are applied; conversely, other areas are indicated where the nature of the problem dictates the reliance on empirical results and test data. Specific problems, properties and equipment are used throughout the presentation to illustrate the various concepts. Presented at the 24th ASLE Annual Meeting in Philadelphia, May 5–9, 1969.
TL;DR: In this article, the life-margin of oscillating caged needle roller bearings is determined in an explicit non-statistical manner, which is the difference between the first macroscopic evidence of spalling fatigue and the end of useful bearing life.
Abstract: The life-margin of oscillating caged needle roller bearings is determined in an explicit non-statistical manner. Life-margin is the difference between the first macroscopic evidence of spalling fatigue and the end of useful bearing life. The bearings were life tested under service conditions closely duplicating those in helicopter rotor vertical and horizontal hinge pin locations. Test results are presented for nineteen bearings lubricated with MIL-L-7808 oil. The use of magnetic chip-detectors and spectrometric oil analysis as failure indicating devices are discussed. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference hold in Atlantic City, New Jersey, October 8–10. 1968.
TL;DR: In this article, the load capacity and power loss of spiral groove bearings, lubricated with a Newtonian, incompressible liquid with a viscosity depending on temperature only, are determined by solving the continuity and momentum equations analytically and the energy equation for the grooves and ridges numerically.
Abstract: The load capacity and power loss of spiral groove bearings, lubricated with a Newtonian, incompressible liquid with a viscosity depending on temperature only, are determined by solving the continuity and momentum equations analytically and the energy equation for the grooves and ridges numerically. It is assumed that the total flow perpendicular to the relative velocity of the bearing parts is zero. This implies that the generated heat is discharged by conduction to the bearing parts only. The effect of the “thermal entrance region” is investigated. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Houston, Texas, October 14–16, 1969
TL;DR: In this article, a d'Arsonval galvanometer system is used to measure frictional forces of small magnitude, ranging from below 0.01 dyne to about 50 dynes.
Abstract: A simple apparatus has been developed to measure frictional forces of small magnitude. It provides a continuous recording of tangential forces ranging from below 0.01 dyne to about 50 dynes. Details of the stick-slip characteristics are thereby recorded. The small normal forces required are applied and controlled by passing a current through a meter movement. The basic element for sensing frictional forces is a d'Arsonval galvanometer system. The frictional force applied to a lever arm produces a torque about the axis of the galvanometer system. A dual photodiode-servo amplifier system provides a correcting current to the galvanometer so that the mechanically imposed torque is automatically balanced. The correcting current is directly proportional to the tangential force. This apparatus has been extensively used in friction studies of individual textile fibers and for fine wire samples. It has also been used for measurements of stylus friction on flat surfaces under small loads. This paper includes a deta...
TL;DR: In this article, a method was described to normalize wear-induced changes in the dynamic friction of surfaces lubricated with an additive in oil solution, by comparing them at equivalent degrees of boundary lubrication, determined by measuring the coefficient of friction of the surfaces in neat white oil.
Abstract: A method was described to normalize wear-induced changes in the dynamic friction of surfaces lubricated with an additive in oil solution. Changing dynamic friction data were normalized by comparing them at equivalent degrees of boundary lubrication, determined by measuring the coefficient of friction of the surfaces in neat white oil. Friction tests were made with three different additives to demonstrate the method and its validity. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference held in Atlantic City, New Jersey, October 8–10, 1968.
TL;DR: In this article, a microfibrous form of colloidal alumina (boehmite) is shown to act as a superior nonencapsulating binder for molybdenum disulfide in the formation of ductile, water-resistant dry lubricant films.
Abstract: Binders that have been tried for powdered, lamellar, dry lubricants have shortcomings such as hindering the realignment of the lubricant particles or encapsulating the lubricants, making a wearing-in process necessary. A microfibrous form of colloidal alumina (boehmite) is shown to act as a superior nonencapsulating binder for molybdenum disulfide in the formation of ductile, water-resistant dry lubricant films. Such films exhibit lower coefficients of friction than have been reported for molybdenum disulfide or graphite films bonded with any other material. These new lubricating coatings have good load-carrying ability and durability at any temperature below the thermal decomposition temperature of molybdenum disulfide (700 F). Optimum performance of these boehmite-bonded films is obtained when: (a) the weight ratio of fibrillar boehmite to MoS2 is near 0.20; (b) the film is 0.2 to 0.5 mil thick; (c) the substrate is hard and highly polished; and (d) the film is applied as an alkaline dispersion (pH = 10...
TL;DR: The extreme pressure properties of fluorides and silicofluorides as lubricants for titanium were studied using the Falex tester as discussed by the authors, and the results showed that the fluorides were superior to potassium or ammonium fluoride in preventing excessive metal build up on the ceramic blocks.
Abstract: The extreme pressure properties of fluorides and silicofluorides as lubricants for titanium were studied using the Falex tester. With water solution of sodium fluoride and water soluble metallic and nonmetallic silica-fluorides, jaw loads of 1500 lb were attained without welding. Use of ceramic blocks in the Falex tester showed the efficacy of the fluorides and silicofluorides in preventing excessive metal build up on the ceramic blocks, or excessive wearing away of the ceramic blocks. Sodium fluoride was superior to potassium or ammonium fluoride, and ammonium silicofluoride was the best of the silicofluorides when combined with sodium fluoride. Alkaline additives were not effective in reducing corrosion of steel and copper and also caused a considerable increase in wear on the titanium. Corrosion was controlled by a mixture of a high molecular weight imidazoline and a rosin amine ethylene oxide adduct and in the concentrations used extreme pressure properties were only slightly affected. Presented as an...
TL;DR: In this paper, the development of a liquid-phase micro panel coker and a vapor phase micro-coker is described, which are intended primarily for use in screening synthetic lubricants on the basis of deposit formation in instances where only research-size sample quantities are available.
Abstract: The development of a liquid-phase micro panel coker and a vapor-phase micro panel coker is described. The devices are intended primarily for use in screening synthetic lubricants on the basis of deposit formation in instances where only research-size sample quantities are available. Each model requires less than 75 ml of sample per test and is capable of operation to 1000 F panel temperature. Both micro coker models were utilized in an experimental investigation of the effects of lubricants, panel temperature, and dry and moist air on lubricant deposition. In addition, the liquid-phase micro coker data are examined in comparison with full-scale panel coker and bearing deposition test results. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference held in Atlantic City, New Jersey, October 8–10, 1968.
TL;DR: In this article, a linear logarithmic relation between the viscosity and the average molecular weight of low molecular weight polyisobutylenes is demonstrated, which is used to indicate an apparent difference in the molecular structures of some polyisometrics.
Abstract: A technique is described which has been found useful for understanding the role played by molecular structure in the viscosity of liquid polyisobutylene polymers. A linear logarithmic relation, between the viscosity and the average molecular weight of low molecular weight polyisobutylenes, is demonstrated. This relationship is used to indicate an apparent difference in the molecular structures of some polyisobutylenes. A linear relation also exists between the molar refraction and a viscosity-constitutional constant in several homologous series of polymers which is useful for classification purposes. Contributed to ASLE by the author.