Dry sliding tribological properties of Cu-WS2 self-lubricating composites at 25–500 °C

Cu-WS 2 composites are being used as self-lubricating materials for various engineering applications. The poor wettability between Cu and WS 2 is a main obstacle for obtaining high-performance Cu-WS 2 . In order to improve the wettability, a thin Cu layer was deposited on the surface of the WS 2 powder through an electroless plating technology. Cu-WS 2 composites were prepared via spark plasma sintering (SPS) using the mix powders of Cu and Cu-WS 2 . Microstructure, mechanical properties and tribological properties of the Cu-WS 2 composites were investigated, and that of the Cu were also comparatively studied. Results show that the WS 2 powder coated with Cu (abbreviated as WS 2 @Cu powder) improves the poor wettability between Cu and WS 2 and meanwhile the distribution of WS 2 . Cu-WS 2 composites sintered below 750 °C could reduce the reaction between Cu and WS 2 and ensure more WS 2 in the composites. Both the coefficient of friction (COF) and the wear rate of the Cu-WS 2 are lower than that of the Cu. A lubricant film leads to the excellent tribological properties as the Cu-WS 2 composites were tested at 25−200 °C. However, the disappearance of WS 2 and the formation of Cu 2 O cause to the decreasing self-lubricating performances at 300−500 °C. With an increase in the test temperature, the dominant wear mechanisms of the Cu-WS 2 composites change from adhesive wear to a mixture of abrasive and oxidation wear, and that of the Cu change from adhesive wear to a mixture of fatigue and oxidation wear.