Influence of α-Al2O3 addition on sintering and grain growth behaviour of 8 mol% Y2O3-stabilised cubic zirconia (c-ZrO2)

Abstract The effect of α-Al 2 O 3 addition on sintering and grain growth behaviour of high purity 8 mol% yttria-stabilised cubic zirconia (c-ZrO 2 ) was investigated. For these purposes, 1 wt.% α-Al 2 O 3 was selected as a dopant in c-ZrO 2 . The slip-cast specimens were sintered at different temperatures between 1150 and 1400 °C. It was seen that doped c-ZrO 2 had a faster sintering rate and lower sintering temperature than undoped c-ZrO 2 . In particular, doped c-ZrO 2 achieved a density of 95% of its theoretical value at 1275 °C, while undoped c-ZrO 2 reached the same value at 1325 °C. The different sinterability of doped c-ZrO 2 and undoped c-ZrO 2 can be attributed to their different behaviour of grain growth. For grain growth measurements, the specimens sintered at 1400 °C were annealed at 1400, 1500 and 1600 °C for 10, 30 and 66 h. It was seen that grain growth rate could be controlled by the deliberate addition of 1 wt.% grain boundary phase of α-Al 2 O 3 . A grain growth exponent of 2 and activation energy for grain growth of 298 kJ/mol were obtained for undoped c-ZrO 2 . The α-Al 2 O 3 containing specimens had a grain growth exponent of 3 and activation energy of 361 kJ/mol. The slow grain growth in doped c-ZrO 2 is attributed to solute ions segregation in grain boundary region. The addition of the grain boundary phase results in limiting matter transfer along the grain boundary resulting in slower grain growth.