The influence of high hydrostatic pressure and powder annealing temperature on the sintering kinetics of Al2O3 was investigated. Dilatometry revealed that the sintering of metastable aluminum oxide phases occurs in two stages, with densification inhibition between these stages. It was shown that the use of metastable γ/θ-Al2O3 phases along with a pressure of 700 MPa reduces the temperature required to obtain high-density corundum ceramics to ~1500–1550°C.
Maletskii et al. (Mon,) studied this question.