FAILURE MODES OBSERVED ON WORN SURFACES OF W-C-CO SPUTTERED COATINGS

During scratch testing, the indenter gives rise to a distribution of s tresses similar to that observed in tribocontacts. In this work, r.f.- sputtered W-C-Co coatings deposited from sintered WC + Co (6, 10 and 1 5 wt.% Co) at various substrate biases were scratched and tested tribo logically and the morphology of the damaged surfaces was analysed. The cobalt content of the coatings is the main factor determining their t ribological characteristics. The failure modes observed on the worn pi n-on-disc tested surfaces are explained and compared with those obtain ed by scratch testing. In spite of it not being possible to establish quantitative results for the wear resistance of W-C-Co coatings from s cratch testing, an estimation can be performed based on the observatio n of the failure modes in the scratch track. Thus scratch testing can be used to predict the tribological behaviour of coated surfaces. This possibility can reduce the number and cost of tribological tests.