Diamond/PSZ Composites Fabricated by Hot Isostatic Pressing and Hot Pressing.

Abstract

Diamond/PSZ composites were tried to sinter by both routes of hot isostatic pressing (HIPing) under 150 MPa at 1423 K for 10.8 ks and hot pressing (HPing) under 36 MPa at 1673 K and 1773 K for 10.8 ks. The all sintering conditions are thermodynamically unstable for diamonds. When the composites were sintered by the HIPing and the HPing at 1673 K, no transformation of the diamond into graphite and no reaction products was detected in the composites by XRD analysis. In the HPing at 1773 K, also no transformation into graphite but the formation of ZrC was found in the composite. The tetragonal phase of zirconia, which is favorable to good toughness, was more remained in composites after HIPing and HPing at 1673 K than that with no diamond. The relative densities were above 97% in the composites containing diamond up to 30vol.% sintered by HIPing and in those up to 10vol.% by HPing. Dispersing diamond was effective to restrain the zirconia grain growth during the sintering in HIPing. The Vickers hardness of the composite containing 10 vol.% diamond was increased as compared with that of the zirconia with no diamond.