Tribological properties of Ni3Al-Ni3Nb-Ag self-lubricating alloys at a wide temperature range

Ni3Al-Ni3Nb-Ag, as a potential high-temperature lubricious material for high temperature applications, is investigated in this work. Tribological properties of two alloys, with ratio of 3:1 and 1:3 between Ni3Al and Ni3Nb at fixed 20 wt % Ag, denoted as NBL60 and NLB60 respectively, sliding against Si3N4 ceramic in air, were studied from room temperature to 900 °C. The results show that the friction coefficients of NBL60 and NLB60 are in the range of 0.46-0.38 and 0.39-0.31, respectively. The wear rate of NLB60 is low to 3 × 10-5 mm3/Nm at 900 °C due to the formed glaze layer, providing wear protection at high temperatures. The phases in the glaze layer are primarily oxide mixtures of AgNbO3 and oxides of Ni and Nb. Synergistic effects of low-moderate temperature solid lubricant Ag and high temperature solid lubricant AgNbO3 play a significant role in lubrication over a wide temperature range.