NbMoWTa-Al₂O₃ 固体润滑复合材料的宽温域摩擦磨损性能

A novel NbMoWTa refractory high entropy alloy-based solid lubricated composite was prepared by high-energy ball milling and spark plasma sintering. The effect of nano-Al₂O₃ as a solid lubricant on the tribological properties of NbMoWTa refractory high entropy alloy in wide temperature range was systematically studied. The results show that the nano-Al₂O₃ particles are uniformly dispersed at the grain boundary and within the grains of the matrix phase of NbMoWTa refractory high entropy alloy with BCC structure, and the microhardness of NbMoWTa is significantly increased caused by strong dispersion strengthened. The nano-Al₂O₃ particles have a significant effect in reducing the coefficient of friction and wear from room temperature to 800 ℃. At room temperature, additing sufficient nano-Al₂O₃ can improve the wear resistance of the composites due to the significant increase in microhardness. At medium and high temperatures, the continuous dense oxidized tribo-layer formed on the surface of the composite plays a critical role in improving the tribological properties. Nano-Al₂O₃ particles assist the oxidized tribo-layer to carry a larger load, improve its compactness and stability, and thus protect the matrix more effectively. In addition, the existences of nano-Al₂O₃ particles can inhibit the excessive volatilization of MoO₃ at 800 ℃.