Tribological Properties of Ni-based High Temperature Self-Lubricating Composite

Ni-Mo-PbO high temperature self-lubricating composites were prepared by spark plasma sintering. Microstructure of the composites was analyzed. The friction and wear properties of the composites were investigated from room temperature to 700 ℃. The oxidation-reduction reaction between PbO and Mo occurred during the sintering process. The phase constituents of the composites consisted mainly of Ni (Mo) solution, Pb and oxides of molybdenum. The friction and wear properties of the composites were temperature-dependent. The friction coefficient firstly decreased and then increased with increasing temperature. The wear rates of the composites firstly decreased and then slightly increased with increasing temperature. The addition of PbO improved the tribological properties of the composites at high temperature. Especially at 500 ℃, the composite exhibited a low friction (0.09) and wear rate 2.8×10^–6 mm³/(N·m). The improved tribological properties of the composites at 500 ℃ were attributed to the formation of a dense and lubricious film which consisted mainly of PbO, small amount of NiO and molybdate.