Sintering of free-standing zirconia granules with different Y ₂ O ₃ concentration

Three kinds of commercial zirconia powders with compositions (1–x)ZrO2–xY2O3 (x = 0, 3 and 8 mol-%) were sintered at 1300–1600°C in their free-standing granules. The as-received powder with x = 0 is monoclinic (M) phase. Both as-received powders with x = 3 and 8 show mixed phases dominated by tetragonal (T). The powder with x = 0 returned to M phase at room temperature after high temperature sintering. The powder with x = 3 transfer from mixed phase (T + M) to single phase T after sintering at 1300°C or 1400°C. Moreover, minor M phase appears again when the sintering temperature is above 1400°C, sintering the powder with x = 8 shows only T phase after sintering at different temperatures.