Alumina-silica-based fiber, ceramic fiber, ceramic fiber complex, retaining seal material, production method thereof, and alumina fiber complex production method

摘要

A holding seal material which has alumina-silica based fibers aggregated into a mat shape as a constituent element. The holding seal material is placed in a gap between a ceramic body capable of allowing a fluid to flow through the inside thereof and a metal shell covering the outer circumference of the ceramic body. In the holding seal material, a crystallization rate is made different depending on portions of the holding seal material. An outer portion of the holding seal material disposed with respect to the metal shell is crystallized at a lower rate than an inner portion of the holding seal material disposed with respect to the ceramic body.