Evolution of contact surface characteristics and tribological properties of copper-based self-lubricating composites under heavy load

Abstract

Abstract The composite material sintered by copper and graphite belongs to 'pseudo-alloy', which reduces its self-lubricating performance to a certain extent. Because WS2 and graphite have similar self-lubricating characteristics, the synergistic lubrication mechanism of copper-based graphite-WS2 (Cu-Gr-WS2) has become a hot research topic in recent years. In this paper, the synergistic lubrication mechanism and friction contact surface characteristics of Cu-Gr-WS2 self-lubricating composites under different friction loads were studied. The results show that the friction coefficient first decreases and then increases under the load from 20N to 110N, and the worn surface roughness first decreases and then increases. There is almost no self-lubricating film on the contact surface under small loads. With the load increasing to 80N, the friction coefficient is as low as 0.115, and a continuous and smooth graphite-WS2 self-lubricating film is formed on the contact surface. The main wear mechanism is delamination wear, and the thickness of the lubricating film is about 14.5nm by XPS etching. When the load continues to increase to 110N, there are many adhesion pits on the lubrication film of the contact surface, and the self-lubricating performance decreases.