Effect of Ag addition on high-temperature self-lubricating behavior of CuNi-based composites

CuNi-based high-temperature self-lubricating composites with BaF 2 /CaF 2 eutectic as a main lubricant were prepared by rapid hot -pressing. The results showed that the addition of BaF 2 /CaF 2 can introduce heterogeneous structures, in which the hard phase of BaF 2 /CaF 2 closely surrounded the soft copper alloy phase. The high strength of the composite was mainly derived from the dislocation strengthening caused by the heterogeneous deformation induced stress, and solid solution strengthening induced by Ag. At 500 degree celsius, the excellent tribological performance was mainly attributed to the combined lubricating effects of Ag, BaF 2 /CaF 2 and metal oxides. Furthermore, the addition of Ag formed concrete and continuous lubricating film on the worn surface, with more fluorides to continuously and stably protect the composite substrate.