Sintering behavior and mechanical properties of alumina-coated zirconia ceramics

By using the chemical co-precipitation method, alumina (Al2O3) films with the nano-scale thickness (∝10 nm; so-called ''core-shell'' structure) could be formed on the surfaces of tetragonal zirconia (ZrO2) polycrystals (Y-TZP) with the average particle size of 65.1 nm. Al2O3 content in the ZrO2-Al2O3 powder was set to be 5 mass%. The temperature that showed a maximum shrinkage rate of the alumina-coated ZrO2 powder compact was 1237 C, and was about 53 C lower than the case of pure Y-TZP compact (1290 C). Relative densities of the Al2O3-coated Y-TZP compacts fired at 1300 C or higher temperatures for 5 h attained 99% or more. Crystalline phases of the Al2O3-coated ZrO2 compacts fired at 1400 C for 5 h were tetragonal ZrO2 and a small amount of α-Al2O3. (orig.)