A morphological study of mullite long fiber prepared using polyvinyl butyral as spinning aids

Morphologies of aluminosilicate gel fiber and mullite long fiber prepared from spinning sol of Al(NO₃)₃·9H₂O, tetraethylorthosilicate and ethanol using polyvinyl butyral as a spinning aids have been studied experimentally. The weight loss of fibers as function of drying time and calcination temperature was summarized and the fiber morphologies at different temperature were also discussed. The results indicated that fiber sample lost the main weight at the first several minutes at 40°C. A main axial crack was observed due to the heat stress if gel fiber was not pre-dried before calcination. Accompanied by weight loss during heat treatment, “black” fibers were shown at the temperature range of 300–500°C and some attachment was observed among fiber surface attributed by the decomposition of organic materials. The actual elimination temperature of organic materials was different from our former heat analysis measurement result, and it could be explained by the pre-treating procedure and high heating rate of heat analysis. The morphological study of mullite fiber calcined at different temperature could help to understand and obtain the mullite fiber with smooth surface.