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

摘要

The study prepared alumina green piecesstarting from a #theta#-phase powder by using acolloidal dispersion and high-pressure filtrationprocedures. A series of sintering treatments for theoptimization of the microstructure of the alumina wasconducted. Four sintering factors were selected andtested by Taguchi method. A detail analysis of thegrain size and fired density were conducted accordingto the designed L9 orthogonal array. The resultsreveal that the ramping rate of temperature near#theta#- to #alpha#-alumina transformation is themost important factor. The best processing conditionswere obtained to get smallest average grain size (3.2#mu#m) or greatest fired density (98.9percent). Thefracture strength and the Weibull distribution ofoptimized alumina were also reported.