Friction and Wear Behavior of Copper-graphite Composites with Different Compositions in Water Environments

摘要

Copper-graphite composites with different copper content are prepared by spark plasma sintering (SPS) at 900°C using copper-coated graphite powder and ordinary graphite powder as raw materials. Two groups of specimens are used for friction testing, including the original specimens and K2Cr2O7-H2SO4- etched specimens. The density, microstructure, Shore hardness, resistivity and friction and wear properties of the samples were investigated using the Archimedes drainage method, scanning electron microscopy, a hardness tester, a resistance tester, and a friction tester. The results showed that the relative density of the samples with different compositions reached about 90%, and with an increase of copper content, the density and the relative density of the copper/graphite composites increased. As the copper content increased from 10 wt% to 50 wt%, the Shore hardness of the composites increased from 37 HSD to 59 HSD. Under dry-friction conditions, with an increase of Cu wt%, the friction coefficients and wear rates of the original speci- mens showed a downward trend, while those of the chemically etched specimens first increased and then decreased. Under water-friction conditions, both the original samples and chemi- cally etched samples show very low friction coefficients, about 0.15 and 0.12, respectively, which are far lower than the friction coefficients (~0.20) obtained under dry-friction conditions. The wear rates of the original specimens decreased with an increase of copper content, while those of the chemically etched specimens increased first and then decrease.