Effects of graphite on the wear and corrosion properties of SiCp reinforced copper matrix composites

Wear and corrosion properties of SiC _p/graphite reinforcement Cu metal matrix composites (MMCs) fabricated by hot pressing were evaluated in the present study. Electron micrographic observations were conducted to clarify the micro-mechanisms of wear and corrosion. Experimental results indicate that the hardness and wear loss increased with the SiCp content and decreased with the graphite content. The wear loss of Cu/SiC _p/graphite MMCs was almost the same as adding graphite more than 5vol%. The material porosity of composites increased with foreign particles (SiC _p and/or graphite) content. The composites were immersed in 3.5 wt% NaCl ( pH=6.7) aqueous solutions for potentiodynamic and corrosion rate measurements. The pure Cu exhibited best corrosion resistance, the Cu/SiC _p composite showed lower, and the Cu/SiCp/graphite composite occupied the worst. The poor corrosive properties of composites were owing to the galvanic and crevice corrosion, which were caused by residual stress/strain and potential incorporation between additions (SiC _p and/or graphite) and Cu matrix. In addition, the corrosive weight loss increased with the increase of SiC _p and graphite content.