High temperature tribological properties of silicon nitride in dry sliding contact against Inconel 718 heated by laser

Ceramic tools have been successfully applied in laser-assisted machining of nickel-based alloys. However, few studies have addressed high temperature dry frictional behavior of ceramics against nickel-based alloys. In this study, tribological tests of silicon nitride in dry sliding against both laser-heated (600 degrees C) and unheated Inconel 718 were carried out. The tribological properties at sliding velocities ranging from 2.5 m/s to 10 m/s were investigated. A finite element simulation model of sliding contact was considered to obtain localized contact surface temperatures. The combination of experimental and numerical results enabled evaluating and analyzing the wear behavior. The results showed that the laser heating modifies the temperature distribution resulting in reduced wear rates of the ceramic up to a critical sliding velocity (7.5 m/s in this particular case). With increasing sliding velocity, a tribochemical layer forms, and becomes thick and unstable, resulting in higher wear of the ceramic at a lower coefficient of friction.