Tribological Behavior of Copper⁻Graphite Composites Reinforced with Cu-Coated or Uncoated SiO₂ Particles

Copper⁻graphite composites reinforced with SiO₂ particles were fabricated by powder metallurgy technique. Electroless copper plating was introduced to improve the interfacial bonding between SiO₂ particles and copper matrix. The microstructure, density, and hardness of the composites were characterized. The tribological properties, such as friction coefficient and wear rate of the composites, were studied using a pin-on-ring tribometer. The results show that the hard SiO₂ can restrict the severe plastic deformation and adhesion contact in the process of wear. At the same time, parts of SiO₂ particles can be broken into fine particles during wear process, which is helpful for decreasing adhesion wear and abrasive wear. Therefore, the addition of SiO₂ leads to increasing friction stability and friction coefficient, and decreasing wear rate. In addition, the electroless copper plating improves the interfacial bonding between SiO₂ and copper matrix, which prevents separation of SiO₂ from copper matrix and further increase tribological properties of the composites.