Effect of Pyrolytic Carbon Interface Thickness on Conductivity and Tribological Properties of Copper Foam/Carbon Composite

To improve electrical conductivity of the carbon-based pantograph strip, a sliding contact material of pyrolytic carbon (PyC) coated-copper foam/carbon composite was fabricated by chemical vapor deposition technology, followed by densifying processes of furan resin impregnation and carbonization. Morphology, electrical conductivity, wear and friction behavior of the composites are investigated to clarify the effect of PyC thickness (from 0 μm to 280 μm) on tribological behaviors and current transfer characteristic. The results show that there is a good interface combination between copper foam and resin carbon matrix in the composites after the improvement of interface wettability by inserting PyC layer. The composite has great advantages in electrical conductivity and density due to the copper foam and PyC layer with three-dimensional structure. With increasing the PyC thickness, both electrical conductivity and wear resistance of the composite have steadily increasing tendency, but friction coefficient has no obvious change. In addition, an analytical model is developed to explore current transfer mechanisms of the PyC-copper foam/carbon composite, and the theoretical predictions are in agreement with the experimental observations, in term of electrical conductivity and porosity of composite preform.