A kind of preparation method of boron-containing silicon nitride fiber

A silicon nitride fiber and fiber technology, applied in the fields of fiber chemical characteristics, rayon chemical post-treatment, inorganic raw material rayon, etc., can solve the adverse effects of fibril structure damage, low B element content, and precursor spinnability and other problems, to achieve the effect of improving stability, high activity and improving mechanical properties

Inactive Publication Date: 2016-09-28
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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  • A kind of preparation method of boron-containing silicon nitride fiber
  • A kind of preparation method of boron-containing silicon nitride fiber

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] (1) 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, and heat up at the same time, the temperature rise system : 2 hours to 500°C, 0.60°C / min to 650°C, hold for 0.5h, 100°C / h to 800°C, hold for 2h. Cool to room temperature with nitrogen gas to obtain highly active Si-N fibers; (2) Boronation of highly active Si-N fibers. After 2 hours, the temperature was raised to 400° C., and gasified butaborane was passed into the decarburization-nitridation system. The reaction time was 24 hours, and nitrogen gas was passed to cool to room temperature; (3) Nitriding of boronized fibers. Introduce high-purity ammonia gas, heat up to 1350°C for 6 hours, and keep warm for 2 hours. Cool to room temperature with nitrogen, Serve.

[0041] figure 1 X-ray photoelectron energy map (XPS) of the prepared boron-containing si...

Embodiment 2

[0044] Put polycarbosilane non-melting fibers in the decarburization-nitriding system, vacuumize, then replace the gas in the system with argon to normal pressure, repeat at least three times; feed high-purity ammonia gas, and raise the temperature at the same time, the heating system: 2 The temperature was raised to 500°C in 1 hour, and then the temperature was raised to 650°C at 0.80°C / min, and then kept for 0.5h, then raised to 1000°C at 100°C / h, and kept for 1h. Cool to room temperature with argon to obtain highly active Si-N fibers; (2) Boronation of highly active Si-N fibers. After 2 hours, the temperature was raised to 450°C, and gasified decaborane was passed into the decarburization-nitridation system. The reaction time was 36 hours, and then cooled to room temperature with argon; (3) Nitriding of boronized fibers. Introduce high-purity ammonia gas, heat up to 1400°C for 6 hours, and keep warm for 1 hour. Cool to room temperature with argon, and it's done.

[0045] ...

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Abstract

The invention relates to a preparation method of silicon nitride fiber containing boron. Firstly, high-activity Si-N fiber is prepared by converting polycarbosilane non-melting fiber, then chemical introduction of a B element is realized by utilizing H2 elimination reaction between excessive N-H in the high-activity Si-N fiber and high-chemical activity boron compound gas, and then nitridation is performed in ammonia gas, so as to prepare the silicon nitride fiber containing boron. Compared with the prior art, the silicon nitride fiber containing boron, which is prepared by adopting the method, has the advantages of high boron content, uniformity in distribution, high nitrogen content and high fiber strength. The preparation method has the advantages of simple process and low cost and is suitable for large-scale production, and an existing decarburization-nitridation system does not need to be changed.

Description

technical field [0001] The invention relates to a method for preparing boron-containing silicon nitride fibers, in particular to a method for preparing boron-containing silicon nitride fibers by converting 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 materia...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): D01F9/08D01F11/00C04B35/584C04B35/622
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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