Method for synthesizing polycrystalline mullite fibers under low temperature condition

The invention relates to a method for synthesizing polycrystalline mullite fibers under a low temperature condition. Mullite fibers with excellent appearance can be obtained under a relatively low temperature condition by use of a method of adding additives to the system; due to the addition of the additives, the reaction temperature can be obviously reduced and then the purpose of reducing energy consumption can be achieved; at the initial phase of the reaction, the additives are added in the form of inorganic salts, while other raw materials are added according to the stoichiometric ratio in a chemical formula, a spinning solution obtained by virtue of hydrolysis, polymerization and concentration is prepared into gel fibers, and finally, the gel fibers are dried and roasted to obtain the mullite fibers; the diameter of the fibers ranges from 3 to 10 microns.