Formation and sintering of 75 mol% alumina 25 mol% zirconia (2-3.5 mol% yttria) composite powder prepared by the hydrazine method

Al2O3/Y2O3-doped ZrO2 composite powders with 25 mol% ZrO2 have been prepared by the hydrazine method. As-prepared powders are the mixtures of AlO(OH) gel solid solutions and amorphous ZrO2. The formation process leading to alpha-Al2O3/t-ZrO2 composite powders is investigated. Hot isostatic pressing has been performed for 1 h at 1500 degrees C under 196 MPa. Dense ZrO2-toughened Al2O3 (ZTA) ceramics with homogeneous-dispersed ZrO2 particles show excellent mechanical properties. The toughening mechanism is discussed.