Effect of carbon type and morphology on the microstructure and properties of carbon/copper composites

Agglomerated brittle graphite and discontinuous matrix have decreased mechanics and friction properties of natural graphite/copper (NG/Cu) composites prepared through spark plasma sintering (SPS) with the blending of graphite and electrolytic copper powder. In that case, microstructure, mechanics and friction properties of NG/ Cu composites were compared with that of carbon particles/cooper (CPs/Cu) composites prepared via ball-milling and SPS. CPs/Cu composites had higher strength and excellent friction properties, due to the uniform distribution of high content CPs (similar to 4 mu m, with carbon fiber structure) in Cu matrix, and similar to 36.40% of low angle grain boundaries (LAGBs) of continuous Cu matrix with finest grain size (similar to 0.90 mu m). The effective fixation of CPs by higher strength Cu matrix, combined with the consistency of microregion performance came from high-density uniformly dispersed of the micron-sized CPs, which significantly reduced the friction coefficient of the C/Cu composites against the steel disc and improved the stability of friction performance. Even at 400 degrees C, the softening of the matrix was greatly weakened owing to the pinning effect of CPs with excellent antioxidant properties on grain boundaries, and CPs/Cu composites still maintain good friction properties.