Tribological behaviours of carbon fibre reinforced PEEK sliding on silicon nitride lubricated with water

Research on the tribological characteristics of carbon fibre reinforced polyetheretherketone (CFRPEEK) sliding on sintered silicon nitride (Si3N4) lubricated with water was conducted on a surface contacted tribo tester. Effects of sliding velocity and pressure have been obtained. It is discovered that the friction pair assumes very small coefficients of friction (generally f ≤ 0.01) and low wear rate in a wide range of velocity and pressure, and there exists an evident running-in process. Sliding velocity has a greater effect on friction than pressure. When sliding velocity is below 3.0 m/s, friction coefficient descends as the velocity increases if normal pressure is kept constant. Once the velocity is beyond 3.0 m/s, it increases with velocity. The worn surfaces were analyzed by a scanning electronic microscope to elucidate the mechanism of friction and wear. It was considered that the transferred film of CFRPEEK to Si3N4 and water lubrication both play very important roles in reducing the friction coefficient and pressure affects friction and wear of CFRPEEK through its influence on surface temperature. In this research, no noticeable wear of Si3N4 can be found. The wear of CFRPEEK arises mainly from material transfer caused by adhesion and mechanical ploughing.