Unlubricated friction and wear behaviors of various alumina-based ceramic composites against cemented carbide

Al2O3/TiC, Al2O3/Ti(C,N), Al2O3/(W,Ti)C, and Al2O3/SiCw alumina-based composites, which provided a reasonably wide range of mechanical properties and microstructure, were produced by hot pressing. The unlubricated friction and wear behaviors of these composites against cemented carbide were studied in air atmosphere using the ring-block method. The friction coefficient and wear rates were measured, and the wear mechanisms were discussed in relation to mechanical properties and microstructure. Results showed that additions of TiC, Ti(C,N), (W,Ti)C, or SiCw to the Al2O3 matrix increased the flexural strength, fracture toughness, and hardness compared to the monolithic Al2O3 matrix. The friction coefficient showed a downward trend with the increasing of the sliding speed, and decreased dramatically with increasing applied load for all the alumina-based composites. The Al2O3/TiC composite showed the highest wear rate, and the Al2O3/SiCw the lowest one under identical test conditions. The higher wear resistance of Al2O3/SiCw composite corresponded to its higher fracture toughness and hardness.