Dry rolling wear of different materials induced by a non-uniform hertzian pressure distribution

Abstract

This paper reports the tribological correlation between the wear behaviour in dry rolling contact with a non-uniform hertzian pressure distribution and the material properties of SAE52100 steel, silicon nitride ceramic (Si3N4) and amorphous metal carbides containing a hydrogenated carbon coating (WC/C). For this examination, a new wear rig was designed as an attachment to a standard Amsler two-roller machine, in which the contact mechanism of any cam/cam follower system can be simulated. The tests were carried out with different contact pairs. The wear behaviour was observed in situ and the mechanisms of damage were examined by optical and electron microscopy as well as laser profiling. Moreover, the changes in different tribological parameters were observed. The results show that the failure mechanism of steel is dominated by adhesion and tribo-oxidation. The ceramic fails typically by microcracking and the failure of WC/C is mostly attributed to mild abrasion followed by adhesion of the substrate steels. Steel vs. steel rollers fail after less than 800 contact cycles, Si3N4 vs. steel after 1090 contact cycles, Si3N4 vs. Si3N4 after 1646 contact cycles, WC/C vs. steel after 145 775 contact cycles and WC/C vs. WC/C after more than 1 million contact cycles. These values are discussed in the light of other microstructural and characterization results.