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Preparation method of boronized silicon nitride fiber

A technology of silicon nitride fiber and fiber, which is applied in the direction of artificial filament of inorganic raw materials, can solve the problems of damage to the fibril structure, adverse effects on the spinnability of the precursor, and low content of B element, and achieve low cost and low equipment requirements , highly active effect

Inactive Publication Date: 2015-08-12
NAT UNIV OF DEFENSE TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

After the B element is introduced into PCS, the B element content is generally low, and it has an adverse effect on the spinnability of the precursor
When the B element is introduced during the crosslinking process, due to the process of removing HCl, methyl, etc., it will cause great damage to the structure of the fibrils

Method used

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  • Preparation method of boronized silicon nitride fiber
  • Preparation method of boronized silicon nitride fiber

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Embodiment 1

[0038] (1) Preparation of highly active Si-N fibers. Put polycarbosilane non-melting fibers in the decarburization-nitriding system, vacuumize, and then replace the gas in the system with nitrogen to normal pressure, repeat at least three times; feed high-purity ammonia, heating system: 2 hours to 500 ℃, 0.50°C / min to 600°C, keep warm for 0.5h, 100°C / h to 1200°C, keep warm for 1h. Cool to room temperature with nitrogen gas to obtain highly active Si-N fibers; (2) Boronation of highly active Si-N fibers. In a nitrogen atmosphere, place the highly active Si-N fiber and sodium borohydride in a decarburization-nitridation system, program the temperature to 450°C, react for 20 hours, and cool to room temperature with nitrogen; (3) Nitrogen of the borated fiber change. Introduce high-purity ammonia gas, heat up to 1300°C for 6 hours, and keep warm for 2 hours. Cool to room temperature with nitrogen, Serve.

[0039] figure 1 X-ray photoelectron energy map (XPS) of the prepared b...

Embodiment 2

[0042] (1) Preparation of highly active Si-N fibers. Put polycarbosilane non-melting fibers in the decarburization-nitriding system, vacuumize, and replace the gas in the system with argon to normal pressure, repeat at least three times; feed high-purity ammonia gas, heating system: 2 hours to 500°C, 0.6°C / min to 600°C, heat for 0.5h, 100°C / h to 1000°C, hold for 2h. Cool to room temperature with argon to obtain highly active Si-N fibers; (2) Boronation of highly active Si-N fibers. In an argon atmosphere, place the highly active Si-N fiber and potassium borohydride in a decarburization-nitridation system, program the temperature to 480°C, react for 30 hours, and cool to room temperature with argon; (3) boronized fiber Nitriding. Introduce high-purity ammonia gas, heat up to 1350°C for 6 hours, and keep warm for 1 hour. Cool to room temperature with argon, and it's done.

[0043] The X-photoelectron spectrum and radial B element X-ray photoelectron spectrum of the prepared ...

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Abstract

The invention relates to a preparation method of a boronized silicon nitride fiber. The preparation method comprises the steps of firstly preparing a high-activity Si-N fiber by transforming an infusible polycarbosilane fiber, carrying out dehydrogenation coupling reaction on excessive N-H in the high-activity Si-N fiber and B-H compounds generated by virtue of pyrolysis of boron hydrides so as to chemically introduce an element B, and carrying out boron hydrides in ammonia gas, so as to prepare the boronized silicon nitride fiber. Compared with the prior art, the boronized silicon nitride fiber prepared by virtue of the preparation method is relatively high in boron content, nitrogen content and fiber strength and relatively uniform in boron distribution. The preparation method has the advantages that the process is simple and convenient, and the cost is low. Compared with SiBN fiber prepared by virtue of a polyborosilazane precursor route, the preparation method has relatively great cost advantage and is applicable to large-scale production, and existing decarburization-nitridation systems do not need to be changed.

Description

technical field [0001] The invention relates to a method for preparing boronizing silicon nitride fibers, in particular to a method for preparing boronizing silicon nitride fibers by transforming polycarbosilane fibers. Background technique [0002] Silicon nitride (Si 3 N 4 ) is one of the materials with the best comprehensive properties of structural ceramics, not only has excellent mechanical properties, high thermal stability, but also has a low dielectric constant. Its decomposition temperature is 1900°C, and its dielectric constant and dielectric loss are 7 and 4×10 respectively. -3 ~4.5×10 -3 , its ablation resistance is better than that of fused silica, and it can withstand thermal shock resistance under flight conditions of Mach 6-7. It is one of the ideal candidate materials for high-temperature wave-transparent ceramic fibers. [0003] The organic precursor conversion method is based on organic polymers (mostly organometallic polymers) as raw materials, and af...

Claims

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Application Information

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IPC IPC(8): D01F9/08
Inventor 谢征芳王军邵长伟宋永才王浩简科
Owner NAT UNIV OF DEFENSE TECH
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