Effect of ZrO2 on phase transformation of Al2O3

This study investigates the effect of ZrO2 on phase transformation of alumina. Alumina and alumina-zirconia composite powders were produced by the precipitation method from aluminum sulfate and zirconium sulfate precursors. Precipitates obtained at 15 degrees C were dried at 80 degrees C for 72 h, and then calcinated at four different temperatures; 1000 degrees C, 1100 degrees C, 1200 degrees C and 1300 degrees C for 1 h. Powders calcinated at 1300 C were pressed uniaxially and sintered at 1600 degrees C for 1 h. XRD and DSC analyses showed that the presence of zirconia retarded the transformation to alpha-alumina. SEM studies on the powders calcinated at 1300 degrees C revealed that both alumina and alumina zirconia particles were 100-300 nm in size and of near spherical shape. Zirconia additions inhibited abnormal grain growth of alumina and provided homogeneous, equaxied grain structure. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.