SYNTHESIS AND MECHANICAL-PROPERTIES OF ALUMINA MGO STABILIZED ZIRCONIA ZIRCON COMPOSITE

Densification conditions of alumina, MgO stabilized zirconia (MSZ) and zircon composite were studied, and sintered bodies were evaluated as cutting tool by the temperature dependence of three-point bending strength. The Mg-spinel formed from Al2O3 and MgO, stabilizer of zirconia, prevented the densification Al2O3-MSZ composite. Thus, the zircon was added to the Al2O3-MSZ composite and then the powder mixture was sintered after molding. The addition of zircon prevented the Mg-spinel formation, and the composite was densified by controlling the cooling rate. Pre-sintering and HIP treatment of the composite which contained 60 wt% Al2O3, 25 wt% MSZ and 15 wt% zircon were performed. The bending strength of the composite did not decrease to 1200-degrees-C, and increased with increase in the content of zircon. On the other hand, high temperature bending strength decreased with increase in the content of zircon. In order to evaluate the composite as a cutting tool, the resistance to fracture was investigated. It was found that the sample, which had a high temperature bending strength, had good resistance to fracture.