Tribological properties of silicon nitride ceramics modified by titanium and subsequent oxygen implantation

A silicon nitride-based ceramic was implanted with 150 keV titanium to a fluence of 10(17) ion cm(-2). Subsequently, the samples were implanted with oxygen using plasma immersion ion implantation (PIII) and conventional beam-line implantation to stimulate the formation of lubricating oxides in the surface. The wear is reduced for all implanted samples. The friction coefficient is slightly higher than in the nonimplanted case for all implantation conditions investigated: although oxide formation in the wear track is suggested by detection of a relatively high amount of oxygen in the wear track as indicated by energy-dispersive X-ray spectroscopy (EDX). We discuss the possible mechanisms that lead to the observed tribological behavior. (C) 1997 Elsevier Science S.A.