Boron-containing silicon carbide fiber and preparation method thereof

A technology of silicon carbide fiber and polycarbosilane, which is applied in the chemical characteristics of fibers, textiles and papermaking, etc., can solve the problems of uneven distribution of boron elements, complicated preparation processes, and complicated preparation processes of boron-containing precursors, and achieves short synthesis time. , The preparation process is simple, and the spinnability is good.

Active Publication Date: 2019-12-31
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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Problems solved by technology

The above-mentioned method for preparing boron-containing SiC fibers also has problems such as uneven distribution of boron elements or complicated preparation processes.
Wang Jun et al. also reported a method for preparing boron-containing silicon carbide fibers. After mixing dimethyldivinylsilane and borane in a certain proportion, they were heated and kept warm to obtain boron-containing monomers, and then mixed with low molecular weight polycarbosilane , obtain boron-containing polycarbosilane precursor after distillation, and then obtain boron-containing silicon carbide fiber (CN104790068A) after melt spinning, non-melting, high-temperature firing and sintering, but the preparation process of boron-containing precursor in this method is also more complicated

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  • Boron-containing silicon carbide fiber and preparation method thereof
  • Boron-containing silicon carbide fiber and preparation method thereof
  • Boron-containing silicon carbide fiber and preparation method thereof

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[0024] In view of the current state of preparation of boron-containing silicon carbide fibers and the existing deficiencies in the prior art, the inventor of this case was able to propose the technical solution of the present invention after long-term research and extensive practice. The technical solution, its implementation process and principle will be further explained as follows.

[0025] An aspect of the embodiments of the present invention provides a method for preparing boron-containing silicon carbide fibers, which includes:

[0026] In a closed reaction vessel, a certain proportion of polysilocarbosilane and boron-containing monomers are synthesized under high temperature and high pressure to generate boron-containing polycarbosilane crude material, wherein the polysilocarbosilane is polydimethylsilane The low-molecular-weight product after high-temperature cracking is liquid at room temperature, with a molecular weight of less than 1000g / mol;

[0027] Dissolving an...

Embodiment 1

[0047] Polydimethylsilane is cracked at high temperature to obtain polysilocarbosilane, which has a molecular weight of 500 g / mol and is liquid at room temperature. Add 300g of liquid polysilocarbosilane and 3g of carborane into the closed device, replace the kettle with high-purity nitrogen three times, and then seal the device; then, start the temperature rise, raise the temperature to 400°C at a certain heating rate, stop the reaction after 6 hours, and react The final pressure is 8MPa. The reaction product was dissolved in xylene and filtered, and the solvent and small molecules were removed by distillation under reduced pressure to obtain boron-containing polycarbosilane (PBCS). For the convenience of comparison, the product obtained by taking the same mass of raw materials and reacting at 350°C for 2 hours is liquid boron-containing polycarbosilane (LPBCS). The infrared spectra of LPBCS and PBCS are as follows figure 1 shown. It can be seen that compared with LPBCS, P...

Embodiment 2

[0052] Add 300g of the liquid polysilocarbosilane in Example 1 and 2.5g of decaborane into the airtight container, replace the kettle with high-purity nitrogen three times, and then seal the device; then, start the temperature rise, and raise the temperature to 410°C at a certain heating rate , The reaction stopped after 4h, and the final pressure of the reaction was 7Mpa. The reaction product was dissolved in xylene and filtered, and the solvent and small molecules were removed by distillation under reduced pressure to obtain boron-containing polycarbosilane (PBCS02).

[0053] As determined by gel permeation chromatography (GPC), the number average molecular weight of PBCS02 is 1120 g / mol, and the softening point is 195°C.

[0054] Melt-spinning the boron-containing polycarbosilane at 300° C. to obtain boron-containing polycarbosilane fibers. The boron-containing polycarbosilane fiber is infusible in air at 185°C for 5 hours to obtain boron-containing polycarbosilane infusib...

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Abstract

The invention discloses a boron-containing silicon carbide fiber and a preparation method thereof. The preparation method of the boron-containing silicon carbide fiber comprises the following steps: in a closed reaction container, carrying out synthesis reaction on polysilacarbosilane and a boron-containing monomer at high temperature and under high pressure to generate a boron-containing polycarbosilane crude material, wherein the polysilacarbosilane is a low-molecular product of polydimethylsiloxane subjected to high-temperature cracking, is in a liquid state at room temperature, and has a molecular weight less than 1000 g / mol; dissolving and filtering the boron-containing polycarbosilane crude material to obtain a spinning-grade boron-containing polycarbosilane precursor; and carrying out melt spinning, non-melting, high-temperature sintering and sintering treatment on the spinning-grade boron-containing polycarbosilane precursor to obtain the boron-containing silicon carbide fiber.Compared with the prior art, the preparation method provided by the invention is simple in process and easy to operate, and the synthesized boron-containing polycarbosilane precursor has the advantages of good spinnability, convenience in adjustment of boron content and the like.

Description

technical field [0001] The invention belongs to the technical field of preparation of ceramic fibers and precursors, and in particular relates to a preparation method of boron-containing polycarbosilane and ceramic fibers thereof. Background technique [0002] Silicon carbide (SiC) fibers have high strength, high modulus, low density, corrosion resistance and creep resistance. More importantly, it has excellent high temperature resistance and oxidation resistance, and can withstand high temperatures above 1000°C in the air without changing its performance. Such high temperature performance is unmatched by other inorganic fibers. Therefore, SiC fibers are mainly used in high temperature resistant composite materials and are important reinforcements for ceramic matrix composites (CMC). Continuous SiC fiber toughened ceramic matrix composites (SiC-CMC) have good thermal stability and strong thermal shock resistance, and are widely used in advanced aerospace structural componen...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D01F9/10
CPCD01F9/10
Inventor 莫高明宋育杰欧阳琴王艳菲皇甫志云何流黄庆黄政仁
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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