Correlations between third body evolution and tribological performance of copper-matrix friction material under abrasive paper interference conditions

Abstract

The influence of the degree of morphological variances of third body on the friction coefficient is a foundational question for understanding the friction mechanism. The correlations between the composition and morphology of third body as well as the surface roughness and the friction coefficient of copper-matrix friction material were investigated using a pin-on-disc tribometer by a method of interface interference caused by various grit size abrasive papers by grinding the friction surface during friction. Friction tests were conducted under friction speeds of 200–800 r/min at a normal load of 0.5 MPa. The results indicate that the friction coefficients increase under dry abrasive paper interference condition. It is generally 0.07–0.09 higher than the noninterference case. Large particle sizes of abrasive paper interference causes the change in the morphology of third body. More specifically, high surface roughness caused by plowing of coarse abrasive paper interference is the main cause for high friction coefficient. This phenomenon is weakened with the increase in speed. And small particle size of abrasive paper interference induces the change in the composition and distribution of third body due to fine SiC particles grinding and embedding into the friction interface. These changes increase the hard spots contact area, exacerbate the abrasive wear at all speeds, leading to a higher friction coefficient.