High-temperature wear behavior of self-lubricating Co matrix alloys prepared by P/M

• The self-lubricating Co–Cr–Mo–Ag alloy was prepared by P/M.
• Ag could be acted as solid lubricant for Co alloy from 22 °C to 1000 °C.
• CA showed the best tribological properties at high temperature.
• The lubricating film played an important role in resisting wear and friction.

In order to balance the strength and lubricating properties of Co matrix alloy at high temperature, Co–Cr matrix high-temperature self-lubricating alloys with addition of molybdenum and silver were fabricated by powder metallurgy technology. The high-temperature tribological behavior of alloys sliding against Si3N4 ceramic ball were investigated by using a ball-on-disc high-temperature tribometer at 10 N and 0.19 m/s starting from room temperature to 1000 °C. Cr and Mo element showed the solid solution strengthening effect on the matrix. The specimen with 8 wt% Mo and 9 wt% Ag showed the best tribological properties over a wide temperature range. The favorable tribological properties were attributed to the combined action of hardness and the solid lubricants including Ag, metal oxides, molybdates and chromates at all the tested temperatures.