A wear model for silicon nitride in dry sliding contact against a nickel-base alloy

The properties of silicon nitride ceramics allow their broad application in extreme tribological conditions. High-temperature sliding contact of Si3N4-base materials against metals will be found more often in future applications, in which the ceramic's wear resistance becomes clearly necessary. In this study, the dry sliding behavior of silicon nitride against Inconel 718 is investigated. Wear experiments were carried out at sliding velocities ranging from 1 to 20 m/s. A finite element wear simulation was constructed by relying on experimentally measured wear rates and COF. The simulations enabled quantifying localized temperature and contact stress fields as a function of geometrical changes due to progressive wear. The experiments showed a transition in wear mechanisms depending on the sliding velocity and frictional power. Cross-sectional analysis of the ceramic samples provided information on the tribochemical processes and the dominant wear mechanisms. Combining analytical and numerical results enabled proposing a schematic wear model. The agreement of this model with common theories of wear is discussed.