Preparation Of Nitrogen-Doped Mullite Fiber by Nitridation Of Silica-Alumina Gel Fiber In Ammonia

摘要

Nitrogen-doped mullite fibers were first synthesized through the nitridation of Al_2O_6-SiO_2 gel fibers in NH_3. The results showed that nitrogen take-up began at 800℃, reached the maximum at 900℃, and then decreased with increasing temperature. The ceramic fibers nitridated at 900℃ were essentially amorphous, but contained a small amount of nano-sized Al-Si spinel crystals. Mullite was formed after nitridation at 1200℃, accompanied by crystallization of x-Sialon and 5-Al_2O_3. The incorporation of nitrogen resulted in the formation of a variety of nitrogen-containing crystalline phases. The grain size of the mullite fibers can be adjusted by changing of the nitrogen content.