Tribological properties and wear resistance mechanism of WC-ZrO2-Al2O3 ceramics

Abstract

Tungsten carbides are typically used in milling and cutting processes, but the tendency for the metallic phase to be easily softened in high-temperature environments makes them susceptible to severe wear during high-speed cutting and repeated friction processes. In this paper, ceramic phase (ZrO2-20 wt% Al2O3 composite powder) was used to replace the metallic phase and to improve the sustainability of the tribological properties of such material. Furthermore, the wear mechanism of WC-ZrO2-Al2O3 ceramics was compared with monolithic WC ceramics. The ZrO2/Al2O3 grains performed a critical function by forming the relief structure during the friction process. This structure was generated in-situ on the worn track and would not be consumed as the friction process progressed. The excellent wear resistance was attributed to the improved comprehensive mechanical properties of the material and the formation of the relief structure. The best tribological properties of WC-ZrO2-Al2O3 ceramics against GCr15 steel balls represented a coefficient of friction of 0.51 and a specific wear rate of 3.3 × 10−7 mm3·N−1·m−1. This success displays a universal approach of the relief structure formed during the friction process for developing other structural ceramics with superior wear resistance.