Microstructural feature and tribological behaviors of pyrolytic carbon-coated copper foam/carbon composite
A novel sliding contact material of pyrolytic carbon (PyC)-coated copper foam/carbon composite was fabricated by a chemical vapor deposition (CVD) technology, followed by several densifying processes of furan resin impregnation and carbonization. Microstructure, electrical and thermal conductivities and current-carrying tribological performance were investigated. The results show PyC crystallites are evenly arranged on the copper foam surface after the CVD process. Because interface wettability between the copper foam and resin carbon matrix is improved by the PyC layer, the composite has a dense structure and a good interface bonding. The composite has obviously more advantages than the carbon-based pantograph strips in the density, electrical and thermal conductivities, due to the copper foam with three-dimensional structure. Friction and wear behaviors were investigated using a current-carrying friction tester. As the electrical current increases, wear rate and wear surface temperature continually increase, and friction coefficient changes from wildly fluctuating to stable. The high electrical current causes high temperature of wear surface and severe wear of oxidization and arc erosion. Copper oxide particles can improve wear surface roughness and change the sliding friction to the rolling friction between the friction couples. In addition, two physical models are schematically illustrated to understand wear mechanism during the current-carrying friction tests.