Friction and wear rate composition dependence of Cu-graphite composites prepared by spark plasma sintering

Cu–graphite composites were prepared by Spark Plasma Sintering from the copper and graphite powders in the range of 15–80 vol % of graphite to investigate the dependence of coefficient of friction and wear rate on the Cu-graphite composites composition. It was observed that with increasing the concentration of graphite the coefficient of friction and wear rate of composites at first decreases from copper values. When critical concentration threshold of graphite is reached (below 15 vol % of graphite) the coefficient of friction of composites becomes composition independent with values in the range of 0.15–0.16 against steel pin 100Cr6. Besides the fact, that there are similar studies on Cu-graphite composites, none of them was investigated the Cu-graphite system prepared in as wide as possible composition range with the different technology and the same powders: It was observed that the dependence of the coefficient of friction on composition does not depend on the different method of preparation (hot isostatic pressing, spark plasma sintering) for identical copper and graphite powders. The wear rate of composites increases from 2.2E-04 mm 3 N −1 m −1 at 15 vol % of graphite up to 3.8E-03 mm 3 N −1 m −1 at 80 vol % of graphite. At low graphite content the adhesive wear occurs: the wear track is U-shaped with raised edges. At high graphite concentrations abrasive wear occurs with wide simple U-shaped wear track. Microhardness of investigated composites linearly decreases from 62 MHV for copper to 2.7 MHV for graphite. • Cu-graphite composites (15–80 vol % graphite) were prepared using SPS. • Coefficient of friction remains stable ∼ 0.15 due formation of graphite-rich layer. • The critical graphite concentration threshold is below 15 vol %. • It is similar to HIP-ed copper-graphite systems made from the same powders. • Wear rate increases and hardness decreases with graphite concentration.