Some Studies on Dehydroxylation-Rehydration Phenomenon of Kaolin of Indian Origin

摘要

Dehydroxylated kaolin has widespread application in the synthesis of mullite ceramics. In the present study, a new source of highly pure kaolin from western part of India was used as a raw material to investigate the dehydroxylation-rehydroxylation behavior utilizing DTA/TGA and FTIR technique. The results showed that kaolin used in this study possesses high degree of crystalinity and retained its structure up to some extent even after dehydroxylation at 700℃ with a tendency to rehydrate. The DTA peak at 1000℃ supports the high reactivity of dehydroxylated kaolin and the peak is associated with the formation of mullite. The SEM study does not reveal any major microstructural changes after dehydroxylation. However, the XRD pattern of raw clay shown kaolin as major phase which converted to amorphous nature after dehydroxylation and subsequent grinding.