Influence of Third Body Evolution on Tribological Property of Copper-Matrix Friction Material by Surface Treatment

The influence of third body evolution and tribological property of copper-matrix friction material were investigated using a pin-on-disc tribometer. The relationship between third body formation during run-in and the third body evolution caused by surface treatment (dry/wet wipe the friction surface and drip water on the friction surface during friction) and the friction coefficient was explained. The results indicated that the friction coefficients during run-in period increase dramatically with friction time increasing initially due to the increasing coverage of third body formation, and then keep stable with friction time increasing because the circulation of third body evolution reaches a dynamic balance between formation-damage-update processes. The friction coefficient decreases under the surface treatment, and the degree of reduction in friction coefficient under the condition of dry wipe < drip water < wet wipe. These can be attributed to that the wipe treatment plays a role as clearing the third bodies on the surface and the lubricated and protective effect of water. The decrement in friction coefficient becomes smaller when the speed becomes higher, because the wiping and dripping water have little effect at high speed.