Effects of Inorganic Additives on the Isotropic Grain Growth Law of High Purity Alumina

Abstract

Based on the isotropic growth law, GSⁿ-GS₀ⁿ=Kt, the n-value of high purity Al₂O₃ was found to be n=2.4 during sintering, and to be n=3 at annealing stage after reaching the theoretical density. The grain growth rates, K-values, of pure Al₂O₃ and of Al₂O₃ doped with additives were evaluated; for example, K (Al₂O₃) =5.11×10^-22 (m³/s) at 1400°C. The influence of ten inorganic additives on the isotropic grain growth law, the pinning effect of the secondary phase on the grain boundaries, and pore elimination are also discussed.