Abstract: In this paper, the sintering kinetic of ZrO₂ was investigated, and the activation energies were also measured.It is found that the mechanism controlled by boundary diffusion is dominant during the densification of ZrO₂. The finer the powder is, the faster the densification process is, but the final relative density ramains constant.The critical relative density for grain growth is 85%, and the effect of the second phase on the grain finement can only be shown when the grain boundaries move.The sintering activation energy of ZrO₂ is 595 ± 65 kJ/mol, and may be obviously increased owing to the presence of the second phase.The activation energy of 700±50 kJ/mol is estimated in ZrO₂ + 10 vol%Al₂O₃. However, it is not affected by Y₂O₃ content, but the densification process is clearly accelerated.There is an optinum content of Y₂O₃ which can influence the final density of ZrO₂.

Key words: ZrO₂, Sintering kinetics, Activation energy