Effect of Cu‒Fe pre-alloyed powders on the friction and wear properties of Cu-based friction materials

Copper-based friction materials containing the Cu‒Fe pre-alloyed powders in different mass fraction were prepared by powder metallurgy method, and the friction properties were tested at different temperatures. The results show that, with the introduction of the Cu‒Fe pre-alloyed powders, the iron participates in the copper matrix and the interface between copper matrix and other components, which hinders the sintering process and reduces the density. The formed pearlite and the participated iron at the interface act as the hard-strengthening phase, which changes the wear mechanism from the adhesive wear of the pure copper matrix to the abrasive wear after adding the Cu‒Fe pre-alloyed powders, resulting in the reduction of friction coefficient at first and then rising. The critical temperature is 200～250 ℃ for maintaining the stable friction coefficient. When the temperature exceeds the critical temperature, the copper on the friction surface softens and its self-lubricating effect leads to the decrease of friction coefficient. 30% Cu‒Fe pre-alloyed powders by mass is the optimum content for the copper-based friction materials, and the copper-based friction materials have the good plasticity of copper and the appropriate amount of the hard phases to strengthen the friction surface.