Study on the High Temperature Tribological Characteristics of WC-Ni Composites

Abstract: The author studied the composition, microstructure and hardness of WC-Ni composites and examined the influence of operating conditions on high temperature tribological properties. It was found that under high temperature the friction-wear characteristics are better than that at room temperature due to the oxycompounds (NiWO, and WO3) formed on the surface of WC-Ni composites. Thr results shown that NiWO4 has anti-friction effect at high temperature and WO3 has anti-wear ability, ft was suggested that NiW04 is the product of W03 reacted with NiO. The microstructure and hardness is changed with Ni content of WC-Ni composite. When content increases Ni converts from dispersed state to continuous state, in contrast? WC converts to dispersed state. In the case of 40% of Ni content the distribution of WC is similar to that of Ni. They appear in as both dispersed state and continuous state. The weight percentage of WC is close to Ni in the bulk (the volume percentage of Ni is 54% when the waight percental is 40%) .When the volume percentage of Ni is close to WC,the NiWO4 has a smooth distribution under 39.2N of load. 1m/s of speed and 600C of temperature, the surface film is homogenous and continuous, and its friction is better. When Ni content is higher than 40%, the composite, with a dispersed WC phase and a continuous Ni skeleton, has no good anti-wear behaviour. However, when Ni content is lower than 40%, the composite with a continuous WC phase, and WC or WC-Ni skeleton, has better anti-wear property.