The Role of Surface Chemistry and Profile in BOUNDARY LUBRICATION 420121
BOTH the geometry and the chemistry of bearing surfaces have a marked effect on performance under conditions of boundary lubrication and the salient features of these factors are discussed in this paper.
It is pointed out that at least one other quantity in addition to the root-mean-square roughness should be specified in grading surfaces for lubrication performance. The presence of loose material or “fuzz” on all commercially finished surfaces is noted.
Data are presented to show that one function of addition agents in oils is to mitigate the bad effect of poor surface finish. The affinity of lubricants for metal surfaces is discussed, and methods for experimentally measuring this property are outlined, together with results.
It is shown that a high affinity or “wettability” is a necessary but not a sufficient condition for a good boundary lubricant. Its molecules should also have the proper structure and the lubricant should contain a surface-active addition agent in adequate concentrations.