Microstructural Optimization of Alumina Prepared from Ultrafine Theta-Phase Powder for High Strength Applications

摘要

The study prepared alumina green pieces starting from a θ-phase powder by using a colloidal dispersion and high-pressure filtration procedures. A series of sintering treatments for the optimization of the microstructure of the alumina was conducted. Four sintering factors were selected and tested by Taguchi method. A detail analysis of the grain size and fired density were conducted according to the designed L9 orthogonal array. The results reveal that the ramping rate of the temperature near θ- to α-alumina transformation is the most important factor. The best processing conditions were obtained to get smallest average grain size (3.2 μm) or greatest fired density (98.9%). The fracture strength and the Weibull distribution of optimized alumina were also reported.