Microstructure and mechanical properties of Al 2O 3/WC composites with Ca-PSZ addition
Abstract
Alumina reinforced with tungsten carbide particles have been successfully used as cutting tool materials. Even the composite (Al 2O 3/WC) meets most cutting tool requirements e.g. high hardness, good chemical and thermal stability as well as wear resistance, its poor fracture toughness are still the main disadvantages. In this work, a variation in hardness and fracture toughness of Al 2O 3/WC composites according to a presence of calcia-doped zirconia (CA-PSZ) was investigated. Ca-PSZ up to 6 wt% was added to the Al 2O 3/WC composites. The powder mixtures were uni-axially pressed and sintered at 1600°C for 2 hours in argon. The microstructures of the composites were observed by SEM. Hardness and fracture toughness were determined by Vickers hardness. Relatively densities of the specimens higher than 96%TD were achieved after sintering. An Addition of WC resulted in a decrease in grain size of Al2O3 matrix. Hardness values of the Al 2O 3/WC composites were similar when compared with the monolithic Al 2O 3. A presence of Ca-PSZ led to higher fracture toughness, but slightly reduced hardnes. It indicated that the Ca-PSZ could enhance fracture toughness of the Al 2O 3/WC composites.
