Polycrystalline mullite fiber, polycrystalline alumina fiber, aluminum silicate fiber are collectively called ceramic fiber. Because they are ceramic materials in inorganic non-metal materials, they are called ceramic fiber. Mullite, aluminum silicate and alumina all belong to Al2O3-SiO2 refractory materials, just because of different Al2O3 contents and different main solid phase composition content, they are called differently. Fiber main crystal phase is aluminum silicate (Al2O3 content 30%-69%), is called aluminum silicate fiber. Fiber main crystal phase is mullite(Al2O3 content 69%-75%), is called mullite fiber. Fiber main crystal phase is alumina(Al2O3 content above 90%), is called alumina fiber. These fiber are cottom fiber by melting solid mineral and made by injection method. These fibers are made into blanket by needle weaving and made into felt and board by adding binder, wet compression and drying.

Crystal refractory fiber is new style super light high temperature insulation material. Because crystal fiber have unique advantages like light weight, high working temperature, good thermal stability, low thermal conductivity, low heat capacity, etc, they are widely used in high temperature insulation area in the world.