Analytical approach to ball‐bearing surface chemistry

Abstract

The surface chemistry of instrument ball bearings, especially those run under boundary lubrication or lubricant‐starved conditions, can be important for bearing performance and lifetime. Auger electron spectroscopy (AES) coupled with argon‐ion sputter profiling was used to study the surface composition of 52100 and 440C bearing steels under various conditions affecting bearing performance. Surface cleanliness is important in bearing preparation; it was found that a glow‐discharge processing removed carbonaceous contamination more effectively than solvent cleaning, but produced an oxide layer of increased thickness. AES studies of 52100 immersed in tricresyl phosphate at 110°C indicated gradual destruction of the oxide and likely formation of iron phosphate after 15 days exposure; this correlates with the TCP‐presoak exposure needed to optimize bearing lifetime. Scanning Auger examination of actual bearing components after use has successfully monitored chemical changes within and outside the wear tracks of inner races.