Performance of lubricants in the rolling friction zone and kinetics of their tribochemical transformations

Abstract

There are two viewpoints on tribology: (1) an independent science that occupies a certain niche in physical chemistry, thermodynamics, and mechanics of interacting bodies and (2) a technology aimed to enhance the reliability and service life of machine elements in contact during relative motion. In any case, this requires the knowledge of physicochemical processes within the real contact zone of interacting bodies, i.e., in the lubricant itself and at its phase boundaries. This predetermines the importance of studying not only tribology, which is recognized for a long time, but also the tribochemistry of lubricant materials. In this study, we systematically analyze the mechanism and kinetics of tribochemical transformations of lubricant materials (oils and greases) in the rolling friction zone and the main directions of their consumption, which determine the break of metal bonds in the structural material of bearings. Based on the proposed kinetic mechanism, one can predict the depth of tribochemical processes and the service life of friction units with accuracy tolerable for practice.

Grease Degradation in Constant Velocity (CV) Joints

“…Used grease from bearing tests was studied (Cann (7,8); Komatsuzaki,et al (9)), and the lubrication and reflow properties of thermally aged greases were investigated (Hurley,et al (10)). Through experiments, the influence of grease on rolling contact wear was measured and analyzed (Mota and Ferreira (11)) and then lubricants in the rolling friction zone and its kinetics were studied (Mel'nikov (12)). In addition a new method for determining the mechanical stability of lubricating greases (Lundberg and Hoglund (13)) was established.…”