摘要:

This investigation shows that below a certain value of the maximum pressure in the region of contact, fatigue cracks are not initiated. This critical value of the maximum pressure is lower the greater the area of contact. In alpha brass the rate of crack initiation increases with increasing values of the maximum pressure, whereas in the Al-Mg-Zn alloy the rate of crack initiation decreases as the maximum pressure increases.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Chicago, Illinois, October 17–19, 1967.

ISSN:0569-8197    

DOI:10.1080/05698196808972203

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Time rates of wear and distance rates of wear are presented as a function of calculated oil film thickness between two cylindrical steel rollers loaded to a maximum Hertz contact stress of 300,000 psi. Wear is divided into a constant wear mode and a transient wear mode depending on the oil film thickness. A negative slope of the curve representing the distance rate of wear versus oil film thickness explains the stabilizing effect on radial surfaces. A positive slope in a narrow range of oil film thickness causes a surface instability due to wear and surface rippling occurs. Transient wear occurs at the thicker oil films. When followed by zero wear rate surface oxide films develop. The total amount worn off during the transient varies greatly with the oil film thickness when using rollers of a given surface finish. Control of oil film thickness by either velocity or viscosity changes due to tempearture produces similar wear effects.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Chicago, Illinois, October 17–19, 1967.

ISSN:0569-8197    

DOI:10.1080/05698196808972204

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The effects of antiwear, EP, and friction modifying additives on the friction of steel-on-steel are greater when blended in more highly refined base oils. To explain this observation, non-hydrocarbons (sulfur, nitrogen, and oxygen compounds) of the types either (a) initially present in less well-refined oils or (b) formed by oil oxidation during use, were added to base blends consisting of a chlorinated wax, a sulfurized terpene oil, or didodecyl phosphite in a highly refined mineral oil. The resulting changes in friction and surface-coating formation were measured as a function of the nonhydrocarbon concentration. The additive effects on friction were canceled selectively by some of the 34 nonhydrocarbons studied at concentrations that could be encountered in less well-refined oils, whereas pure hydrocarbon additions had little effect. Mechanisms for the observed friction and surface coating changes have been proposed.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Chicago, Illinois, October 17–19, 1967.

ISSN:0569-8197    

DOI:10.1080/05698196808972205

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A system is described whereby a clear map is obtained of the contact between a metal (steel) ball rolling against a plate glass disk. This is achieved by mounting the disk in an air bearing and coating its surface with a thin layer of chromium that partially reflects the light, allowing good interference patterns to be formed. The effect of load (giving stresses to 100,000 psi) and speed and viscosity is demonstrated for a wide range of fluids. A complete run can be carried out with at most 5 ml of sample. It is shown that load hardly alters the film thickness in the middle of the contact but does affect the minimum film thickness, which is in the side lobes. By using a calibrated oil the pressure-viscosity coefficients of the fluids can be determined. The rate of shear is very high, between 0.1 and 40 million sec−1and the flow orientation of polymer thickened oils is clearly marked as well as the molecular orientation postulated by Bondi. For most fluids, except the polymer thickened oils and silicones, the fluid structure influences the film thickness primarily through its effect on viscosity and pressure viscosity.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Chicago, Illinois, October 17–19, 1967.

ISSN:0569-8197    

DOI:10.1080/05698196808972206

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Thermogravimetric oxidation data are presented for fifteen refractory metal dichalcogenides. Interpretation of these data is supported by oxidation thermograms of the chalcogens and the refractory metals and by X-ray diffraction analysis of the oxidized products. The effects of humidity, heating rate, and particle size on oxidation of the dichalcogenides are presented. Thermogravimetric analysis is shown to be helpful in detecting impurities, such as unreacted elements, in commercial samples. Some dichalcogenides are shown to retain the same relative oxidation stability, when bonded in thin films with a ceramic, as for pure powder samples. A table is presented summarizing these oxidation characteristics together with information from the literature on crystal structures, electrical resistivities, and densities.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Chicago, Illinois, October 17–19, 1967.

ISSN:0569-8197    

DOI:10.1080/05698196808972207

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The performance of a synthetic MoS2film, produced by electrodeposition of molybdic oxide followed by a temperature-pressure H2S conversion to a molybdenum sulfide compound, is examined under extreme pressure conditions immersed in various fluids. Friction wear and EP characteristics, measured on various test machines, are compared to those of the fluids alone and also to conventional bonded films.

ISSN:0569-8197    

DOI:10.1080/05698196808972208

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The lubricating action of electroplated gold on 52100 steel and 440 C stainless steel in sliding under 68-kg load was examined with a tester consisting of a single rub block loaded against a rotating disk. The advantage obtained with gold plating was that of low wear while the coefficient of sliding friction remained high. The wear life of thick films was much longer; one 20 μ film had a wear life of 150,000 revolutions, while 1 μ films had wear lives of about 3000 revolutions. Silver, copper, and two gold alloys plated to the appropriate thickness were able to extend the wear life to several thousand revolutions while nickel was not effective at all. The failure of the plated films was usually marked by a rapid increase in wear rate. With thick gold alloy films, wear debris in the form of flakes were obtained in addition to irregular shaped particles. The appearance of the wear track indicated that the gold film underwent considerable plastic deformation.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Chicago, Illinois, October 17–19, 1967.

ISSN:0569-8197    

DOI:10.1080/05698196808972209

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

An analysis is presented showing the manner in which an initial point disturbance on the surface of one disk of a pair of radially loaded disks rolling and sliding in contact will grow and propagate other surface disturbances on both disks. In the analysis it is assumed that an area becoming disturbed will be able to cause disturbances on surfaces which come into contact with it. The patterns of the disturbances formed have been compared with scuff patterns on pairs of failed disks, and significant similarities are shown. The number of disturbances and the spacing of the leading edges of the disturbances are similar to the number and spacing of the scuff marks. The analysis gives lengths of the disturbances somewhat longer than the scuff marks. It is concluded that the analysis is helpful in understanding failures on disks, and it can be extended to scuff propagation on gears.Presented as an American Society of Lubrication Engineers paper ASLE/ASME Lubrication Conference held in Chicago, Illinois, October 17–19, 1967.

ISSN:0569-8197    

DOI:10.1080/05698196808972210

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A study was conducted to determine the feasibility of lubricating worm gears with bonded solid film lubricants. An apparatus for determining gear efficiency and lubrican film wear-life was fabricated. Several tests using conventional oil lubrication were conducted to establish baseline gear efficiency data. Efficiency and wear-life tests were made with four solid lubricant films, two of them incorporating MoS2and Sb2O3in organic polyimide resin binders, and two using MoS2, graphite and gold or bismuth in an aluminum phosphate or sodium silicate binder. Experimental data indicate that solid film lubrication of worm gears is feasible, without a serious loss of efficiency in situations where limited wear-life is acceptable.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Chicago, Illinois, October 17–19, 1967.

ISSN:0569-8197    

DOI:10.1080/05698196808972211

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor