An investigation on tribological and electrical behaviour of conventional and microwave processed copper-graphite composites

The effect of graphite content and sintering mode on the tribological and electrical properties of copper has been studied by incorporating varying proportions of graphite flakes (0, 8, 15, 25 and 32 vol%) following powder metallurgy route. The sintering of green compacts was accomplished by microwave and conventional processes at 900 °C with a heating rate of 5 °C min^-1 and 20 °C min^-1, respectively, and holding time being 60 min for both processes. As expected the densification was observed higher in microwave heating than conventional process. Microstructural examination of microwave samples revealed a fine-grained microstructure. Pin-on-Disc wear test exposed excellent self-lubricating nature of these composites. Best coefficient of friction values were observed for microwave sintered composites. Microwave sintered samples exhibited better hardness, coefficient of friction (COF) and electrical conductivity as compared to their conventionally sintered counter parts. Morphologies of polished surfaces were analyzed to predict the wear mechanisms involved.