Tribological performance of quaternary CrSiCN coatings under dry and lubricated conditions

This paper presents an experimental study of friction and wear performance of quaternary CrSiCN coatings deposited on a hardened H-13 steel substrate by a plasma enhanced magnetron sputtering (PEMS) technique. Friction and wear tests were conducted with a reciprocating line contact between a hardened 4370 steel roller and coated and uncoated flat specimens under dry and lubricated conditions. The effects of coating thickness (1, 3.5 and 7.5 µm) on the mechanical properties, friction and wear performance were also assessed. In dry sliding, the friction of coated surfaces was about the same as for uncoated surfaces, except for the 1-µm coating, which had higher friction. Friction for coated surfaces under lubricated contact was in general higher than for uncoated surfaces. There was no measurable wear on any of the coated surfaces, under either dry or lubricated conditions. However, wear was higher on the steel roller counterface sliding against the coated surfaces, with the amount of wear proportional to the mating coating thickness. The effectiveness of formulated lubricant additives was also modified by the coating, resulting in major effects on friction and wear behavior. This reduction in lubricant additive efficacy is due to the fact that the additives were designed and optimized for ferrous surfaces.