Effect of the ratio of graphite/pitch coke on the mechanical and tribological properties of copper–carbon composites

Copper–carbon composites with pitch coke as reinforcement and the graphite/pitch coke ratio of 10/90, 30/70, 50/50, 70/30 and 90/10 wt% were prepared using compression molding and sintering method. The bending strength and micro-hardness of the composites were measured by a universal tester and Vickers hardness tester, respectively. The friction and wear behaviors of the composites were evaluated using a block-on-ring wear test machine. The fracture surfaces and worn surfaces were investigated by means of scanning electron microscopy (SEM). The results show that the bending strength and micro-hardness of the copper–carbon composites increase as the content of pitch coke increases and reach a maximum of 64.27 MPa and 101 HV when the ratio of graphite/pitch coke is 30/70 wt%. The friction coefficient value of the composites increases significantly with increasing the content of pitch coke, varying from 0.10 to 0.26. The wear rate of the composites reaches a minimum of 2.21 × 10−7 mm3/N m at 30/70 wt% of graphite/pitch coke. The wear mechanism of the composites is mainly adhesive wear accompanied by abrasive wear. When the ratio of graphite/pitch coke in composites is 30/70 wt%, only the slight adhesive wear exists.