Failure modes observed on worn surfaces of W-C-Co sputtered coatings

Abstract

During scratch testing, the indenter gives rise to a distribution of stresses similar to that observed in tribocontacts. In this work, rJ.- sputtered W-C-Co coatings deposited from sintered WC + Co (6,10 and 15 Wl.% Co) at various substrate biases were scratched and tested tribologically and the morphology of the damaged surfaces was analysed. The cobalt content of the coatings is the main factor determining their tribological characteristics. The failure modes observed on the worn pin-on-disc tested surfares are explained and compared with those obtained by scratch testing. In spite of it not being possible to establish quantitative results for the wear resistance ofW-C-Co coatings from scratch testing, an estimation can be performed based on the observation ofthe failure modes in the scratch track. Thus scratch testing can i:>eused to predict the tribological behaviour of coated surfaces. This possibility can reduce the number and cost of tribological tests.