Improving the mechanical and tribological properties of copper using MnS: In-situ internal vulcanization method and microstructural analysis

The good properties of self-lubricating phase MnS in steel inspire us that MnS can improve the mechanical and tribological properties of Cu, while the poor wettability of MnS with the Cu matrix become the key problem of MnS/Cu self-lubricative material. Here we proposed an in-situ internal vulcanization method to improve the interface bonding, and produced MnS/Cu material by vulcanizing of Cu-Mn alloy powder at high temperature. After sintering, the Mn element in the Cu-0.15 wt % Mn (LMn) and Cu-0.84 wt %Mn (HMn) alloy forms MnS/Cu material recorded as LMnS and HMnS. After forging, the yield strength of LMnS and HMnS samples are 74 MPa and 89 MPa, respectively, which are 19.4 % and 43.5 % higher than that of pure copper. And the friction coefficients are 0.21 and 0.15, which are 34 % and 53 % lower than that of pure copper. The microstructures illustrated that the high strength and low friction are mainly ascribed to the second phase strengthening and self-lubrication action of MnS.