Study of wear and micropitting in rolling/sliding contacts operating under boundary lubrication conditions

Abstract

Rolling contact fatigue is a common failure mode in gears and bearings. However, this failure mode is getting greater attention due to the increasing tendency to use lower viscosity lubricants to reduce losses. Though several types of research have been done over the past decades, there are still scopes for further investigations. This study aims to study the effect of the slide to roll ratios (SRR), surface roughness and surface treatment on wear and pitting behaviour under realistic contact conditions. Fatigue and wear damages were quantified by studying the surface topography alteration at different contact cycle intervals.It was found that under boundary lubrication, initiation of micropitting took place in almost all test runs. However, once the adhesive wear mechanism activated at a higher contact cycle, the initially formed micropitted area started to wipe off. Moreover, for an extended test period and high sliding, wear volume is almost similar irrespective of SRR. Later, a surface treatment was studied, which was found effective in delaying the micropitting initiation by improving the tribological parameters compared to the untreated samples.