Effects of nanoscale morphology on the abrasion of steel by diamondlike carbon

Abstract

Previously we showed that the abrasiveness of a coating is closely related to its hardness. In the present work we use a ball-on-disk apparatus to examine the abrasive characteristics of a tungsten-containing diamondlike carbon coating and a metal-free diamondlike carbon coating deposited on steel coupons. We find that roughness with horizontal dimensions on the nanometer-scale is strongly correlated with abrasiveness, while roughness with horizontal dimensions on the micron-scale is not correlated with abrasiveness. The nanometer-scale—but not the micrometer—scale-structure is quickly polished smooth by sliding against steel, explaining the drastic reduction in the abrasiveness of the coating that we have observed.