Effect of LaF3 on the Properties of Pb-Free Cu-Based Self-Lubricating Composites

A strategy involving the use the rare-earth compound LaF 3 with good lubrication and stability properties as a filler in the preparation of Cu-based composites was proposed to solve the problem of poor wear resistance in Pb-free Cu-Bi materials. The influence and regulatory mechanism of LaF 3 content on the mechanical and tribological properties of these composites were studied. The results indicate that LaF 3 has a good refining effect on Cu alloy grains, and LaF 3 and Bi are distributed in a network along the grain boundaries of the Cu alloy in the material. As the LaF 3 content increases, the mechanical properties and friction coefficient of the composite gradually decrease, and the wear rate first declines and then increases. The wear resistance of Cu-Bi composite containing LaF 3 mainly depends on the mechanical support provided by the matrix. When the LaF 3 content is higher than 6%, the composite strength is extremely low, and the increase in lubricant content at the friction interface does not play a decisive role in the material wear behaviour. The material wear rate increases with the increase in LaF 3 content. Therefore, using 6% LaF 3 is recommended to improve the wear resistance of the material and maintain a balance among its mechanical properties, antifriction and wear resistance.