Preparation method of polysilazane for preparation of SiCN nonoxide ceramic fibre

Abstract

A preparation method of polysilazane for preparation of SiCN nonoxide ceramic fibre relates to a preparation method of high molecular weight polysilazane. According to the method, a protective measure is taken by introducing nitrogen into a reaction system; a repetitive ammonolysis reaction is carried out on reaction products from the first step to ensure that the reaction in the first step is completely finished so as to raise reaction yield; and based on the products from the first step, activated thermopolymerization is carried out for intermolecular crosslinking so as to obtain high molecular weight polysilazane. By a systematic desensitization method, hydrolysis of raw materials, methyl hydrogen-dichlorosilane and methyl vinyldichloridesilane, which are sensitive to water and the air, is prevented so as to guarantee that the reactions can be carried out smoothly, and the purpose of raising quality and yield of the low polymer product is achieved. By a repetitive reaction method, the ammonolysis reaction is more thoroughly completed so as to achieve the purpose of uniform molecular weight of the low polymer. By the activated thermopolymerization method, intermolecular crosslinking of the low polymer is realized to form a high polymer so as to achieve the purpose of obtaining the high molecular weight PSZ (200,000).

Description

technical field [0001] The invention relates to a method for preparing high molecular weight polysilazane, in particular to a method for preparing polysilazane for preparing SiCN non-oxidized ceramic fibers. Background technique [0002] Ceramic fiber is a kind of flexible solid material with a circular cross section and a large aspect ratio, which exists in a stretched form. It has light weight, good thermal insulation performance, good thermal stability, good chemical stability, easy processing and convenient construction. And other advantages, in machinery, metallurgy, chemical industry, petroleum, ceramics, glass, electronics and other industries have been widely used. [0003] In recent years, with the development of aerospace and national defense industries, the requirements for ceramic fibers have become higher and higher. Traditional ceramic fibers can no longer meet the needs. Only light weight, thermal shock resistance, creep resistance and relatively high tensile ...

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Problems solved by technology

[0006] In addition, there are also literatures that use methylvinyldichlorosilane and methylhydrogendichlorosilane as raw materials to prepare transparent liquid precursor PSZ through ammonolysis reaction and catalytic photopolymerization reaction, but the prepared precursor has a low molecular weight and is difficult to use in a liquid state. Preparation of Ceramic Fibers by Melt Spinning

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