Experimental analysis of chromium molybdenum coatings under mixed elastohydrodynamic lubrication for film thickness, friction, and wear characterizations

This research aims to evaluate the tribological performance of chromium molybdenum (CrMo) coatings under point and line-contact mixed elastohydrodynamic lubrication. This article studies the coatings made from two different methods and treated in an electrifying process of different durations, which produced microchannels and micropockets in the surfaces. The resulting surface topographies had varying impacts on lubricant film thickness, friction, and wear. Root-mean-square roughness (Sq) and porosity are used to characterize the surfaces and their performances in terms of film thickness, friction, and wear. The results suggest that the coated surfaces with a lower Sq and porosity density tended to yield higher film thickness. However, their influence on friction is complicated; lower roughness and porosity are preferred for lower wear, but certain levels of small roughness and surface pores may help to reduce boundary lubrication friction when compared with the frictional behaviors of porosity-free surfaces and those with higher roughness and higher porosity.