摘要:

The arrangement of atoms in crystalline materials is discussed with reference to lattice, planes, and crystal structure. The effect of atomic structure is considered in terms of its influence on mechanical properties with particular emphasis an those related to friction, namely deformation and shear. Friction data are presented for body-centered cubic, face-centered cubic and hexagonal metals, as well as for crystals of inorganic compounds. The data were primarily obtained in a vacuum environment where the effects of material structure on friction could be measured without the presence of contaminating surface films. The friction results presented are for various planes and for various directions on the planes of single crystals. Data are also presented to show the relation of observation with single crystals to those with polycrystalline materials. The data indicate that friction is anisotropic and is generally lowest on the greatest atomic density planes of crystalline materials when sliding in the direction of most closely packed planes. This relation appears to hold for many crystals of inorganic compounds as well as for various crystal forms of metals. Crystal structure, recrystallization, and surface texturing as well as ordering of atoms in alloys are all shown to exert an influence on friction.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:10.1080/05698196808972212

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Observations have been made of the wear from an SAE 1113 steel pin specimen rubbing on a SAE 113 steel disk in a normal laboratory atmosphere in relation to normal load (0.5–10.4 lbf), slidinq speed (21–188 ft/sec), sliding distance and track history. As a function of sliding distance, three regions are observed; (i) initial severe wear, (ii) mild wear resultinq from the formation of oxide layers on both the pin specimen and transferred particles adhering to the track, (iii) a milder wear, due to the attainment of a uniform track condition. The wear rate measured in (ii) is observed to be proportional to normal load for constant (normal load)1/2× (sliding speed) provided that the magnitude of this parameter is insufficient to cause periodic removal of the surface film. This conclusion is shown to be compatible with earlier theoretical predictions when the presence of an oxide layer was pre-supposed. Unlike the coefficient of friction which is primarily determined by the pin surface condition only, the pin wear rate depends on the conditions of both the pin and track surface.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Chicago, October 17–19, 1967.

ISSN:0569-8197    

DOI:10.1080/05698196808972213

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The authors have previously observed periodic changes in the frictional force and wear rate in unlubricated sliding between SAE1113 steel surfaces. Also the steady-state value of the coefficient of friction, f, and the periodic time of surface breakdown, T, were observed to be continuous functions of (normal load, W)½× (sliding speed, U).

ISSN:0569-8197    

DOI:10.1080/05698196808972214

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Oxygen diffusion through the lubricant film is an important factor in corrosive wear, a type of wear where the primary attack is the formation of iron oxide at the rubbing surface. Experimental data were obtained in a ball-on-cylinder device and quantitatively correlated with oxygen availability by a mathematical model. This model assumes two parallel surfaces separated by a small distance, one surface moving with respect to the other. The lubricant at the inlet is saturated with oxygen, which diffuses to the stationary surface to form iron oxide. The iron oxide is removed immediately by the rubbing motion. From the analysis the average clearance predicted was about 10 microinches, a reasonable figure. For the condition used experimentally, essentially all of the oxygen entering the system will diffuse to the surface and be consumed. Thus, differences in mass diffusivity are not important in determining the wear rate. The experimental observations, in agreement with the theoretical prediction, show that corrosive wear increases with oxygen concentration and sliding speed.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:10.1080/05698196808972215

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Solid lubricating compacts of tungsten diselenide-gallium alloys are currently under development for use as self-lubricating members in high speed-high temperature ball bearing systems. The material is of considerable interest due to the fact that it resists oxidation at temperatures three times higher than pure tungsten diselenide. This paper discusses initial studies of the physical and chemical changes that occur in these compacts during a heal-treating cycle required in their fabrication. Speculations regarding the mechanism responsible for their oxidation resistance are presented.Presented as an American Society of Lubrication Engineers paper at the Lubrication Conference held in Chicago, Illinois, October 17–19, 1967.

ISSN:0569-8197    

DOI:10.1080/05698196808972216

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Experiments were conducted with 1.5 inch diameter hydrodynamic journal bearings in liquid sodium at 500 and 800 F, speeds to 12,000 rpm and unit loads to 31 psi. The stability characteristics of five different geometries and the wear and seizure properties of several material combinations were investigated. Tilting pad bearings were most stable. Combinations of a cobalt alloy with nickel alloys or with a titanium carbide cermet showed the best wear and seizure properties.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:10.1080/05698196808972217

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A method of combining thin-layer chromatography with activation analysis to measure quantitatively the individual impurities in tricresyl phosphate (TCP) is described. The relative amounts and types of impurities found in commercial grades of TCP are discussed. Preparative thin-layer chromatography and iron powder chromatography are applied to produce TCP samples with known concentrations of several impurities. The use of the four-ball wear tester as a method of determining trends in wear values as a function of base stock and additive quality is demonstrated. The relationship of acid phosphate rather than TCP concentration to antiwear properties of compounded lubricants is suggested by transition load studies.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:10.1080/05698196808972218

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A detailed literature survey has shown that considerable controversy exists on the mode of action of organic sulfur compounds as load-carrying additives. Previous work by the authors, using four ball extreme-pressure and wear tests, has suggested that under mixed lubrication (antiwear) conditions, organic disulfides are adsorbed on to the metal surface with cleavage of the sulfur-sulfur bond to form an iron mercaptide layer. However, under more severe conditions such as exist in the extreme-pressure region, cleavage of the carbon-sulfur bond occurs to give an inorganic sulfur-containing layer. Thus the different relative performances of disulfides in the mixed lubrication and extreme-pressure regions are readily explained. This paper now presents the results of a detailed examination of the wear scars obtained with certain disulfides using an electron probe microanalyser. The results illustrate the use of this new technique for studying the nature of worn surfaces but, even more important, lend strong support to the suggested mechanism of action of organic disulfides. The results of this study also offer an explanation for the apparently conflicting rig test results often reported in the literature.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:10.1080/05698196808972219

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The elemental interactions between asperities of ball and flat surfaces in contact are described by considering these factors: (a) the influence of lubricant supply and distribution around the test balls on the kinematics of ball motion and surface velocities; (b) the microgeometry statistics of the contacting surfaces, defining the size, shape and distribution of individual asperities; (c) the (partial) elastohydrodynamic film formed in the Hertz contact area as it influences the average spacing between the contacting surfaces. By joint operation of these factors, individual asperity interactions take place and were observed by way of their effects on friction and their electrical conductivity behavior. On the basis of the observations, a tentative model of the asperity interactions is suggested.

ISSN:0569-8197    

DOI:10.1080/05698196808972220

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor