Anomalous grain growth during hot isostatic pressing of magnesia ceramics made from starting powders with different coarse/fine mixing ratios

The influence of coarse powder on grain growth during hot isostatic pressing (HIP) was examined. Powder mixtures containing 0%, 0.5%, 5% and 20% coarse powder were prepared. The magnesia sintered without pressure was subjected to HIP at 1600 °C for 0.5 h at different pressures. The samples produced from fine powder had the largest grains after HIP treatment, although they had the smallest grains before it. The optical transparency of the HIP-treated magnesia ceramics increased with grain size.