Effects of Titania Addition on the Preparation of Transparent Alumina by Sol-Gel Method

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Transparent alumina was successfully prepared by the sol-gel method using aluminium isopropoxide (APO) as a starting material, and effects of titania (TiO_2) addition on the formation process of transparent alumina and mechanical properties of transparent alumina were studied. The preparatory procedure for the transparent alumina was as follows : (1) APO was hydrolyzed in dilute HCl or HNO_3 solution of pH=2 (H_2O/APO=100 molar ratio), resulting in the formation of white cloudy solutions. (2) These solutions became optically transparent after peptized at 95℃ for 2-3 days. (3) These solutions were dried at very low evaporation rates of 1.0 to 4.0×10^<-2>g/dm^2・day, and these transparent alumina were prepared. On heating, the resultant alumina changed from transparent to translucent at 200-300℃, became transparent again at 500-900℃, and finally dense alumina ceramics were prepared at 1200℃. The addition of titania to APO did not affect the forming behavior of the transparent alumina, but greatly improved its mechanical properties such as bending strength and thermal shock resistance.
東海大学の論文