硝酸を触媒としたゾルーゲル法で調製したアルミナゲルの結晶化挙動 : 800℃での完全なα化

概要

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Alumina gels were prepared from aluminum-sec-butoxide by sol-gel method at 0℃ using HNO_3 as a catalyst. The crystallization behavior of the gel was compared with that of HCl-catalyzed alumina gels. α-Al_2 O_3 did not form until 950℃ in HNO_3-catalyzed gels, while HCl-catalyzed one partially transformed to α-Al_2O_3 around 500℃. Corundum-seeding affected crystallization in a different way as compared to the HCl-catalyzed one, i.e., the α-transformation in the temperature range of 800 to 1000℃ was better enhanced by seeding and was completed at 800℃ when seeded to a level of 5 mass%. It was considered that NO_3 ions assisted the building of a gel structure in which aluminum or oxide ions are readily diffused at temperatures higher than ～800℃.
社団法人日本セラミックス協会の論文
2002-11-01