Preparation method of high temperature resistant multi crystal silicon carbide fiber

A polycrystalline silicon carbide, high temperature resistant technology, applied in the chemical characteristics of fibers, textiles and papermaking, single-component synthetic polymer rayon, etc. Additives and other problems, to achieve the effect of easy continuous production, improved mechanical properties and weaving, and excellent mechanical properties

Inactive Publication Date: 2003-04-16
NAT UNIV OF DEFENSE TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, although US5071600 mentions that polycrystalline SiC fibers can be prepared by introducing >0.2wt% B in the precursor by reacting boron-containing compounds with PCS or simply blending, the purpose of adding boron-containing compounds here is only to introduce The only sintering aid B, cannot introduce other sintering aids, and the patent does not describe this compound, nor does it give any examples, the mechanical properties and weaving properties of the prepared silicon carbide fibers are still unsatisfactory

Method used

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Examples

Experimental program
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Effect test

reference example 1

[0030] 200g of dimethyldichlorosilane and 80g of sodium metal were placed in a 2000ml three-neck flask containing xylene, and stirred and reacted at a constant temperature of 100°C for 10 hours. The precipitate was removed by filtration and washed 5 times with methanol. Vacuum drying at 100°C yields white polydimethylsilane.

[0031] Take 100 g of polydimethylsilane and place it in a synthesis device, slowly heat it up to 450° C. under the protection of nitrogen, and keep it warm for 8 hours for pyrolysis polymerization. The synthesized product was dissolved in xylene, filtered, heated to 300°C, distilled under reduced pressure at 100mmHg, and polycarbosilane (PCS) was obtained after cooling. The prepared polycarbosilane has a number average molecular weight of 1450, a melting point of 210-220° C., a molecular weight dispersion coefficient of 1.68 and a reaction yield of 60.5 wt%.

reference example 2

[0033] Take 50g of diphenyldichlorosilane, 70g of dibromomethane, 30g of phenylboron dichloride and 50g of sodium metal in a 2000ml three-necked flask containing xylene, and stir and react at a constant temperature of 100°C for 10 hours. The precipitate was removed by filtration and washed 5 times with methanol. Vacuum drying at 100° C. yielded 81 g of liquid polyborocarbosilane (PBCS) with a linear structure. Its number average molecular weight is 10300, and the B content is 3.6wt%.

reference example 3

[0035] Take 168g of dimethyldichlorosilane and 100g of methyldichlorosilane in a 3000ml three-necked flask containing xylene, keep the temperature constant with an ice-water bath, and feed high-purity ammonia gas while stirring until no HCl gas is generated in the reaction system. Complete, add 10ml of ethylenediamine to flocculate the precipitate, filter and distill off the solvent to obtain a light yellow silazane oligomer.

[0036] Dissolve 100g of silazane oligomer in xylene, place it in a 3000ml flask, heat to boiling, and slowly introduce 0.3mol of BCl while stirring 3 gas. Evaporate the solvent to obtain brown viscous polyborosilazane (PBSN). Heating to 300° C., refluxing for 5 hours to obtain brittle solid polyborosilazane, the number average molecular weight is 800, the melting point is 100-110° C., and the reaction yield is 95%. The B content is 2.5 wt%.

[0037] 100 g of silazane oligomer was dissolved in xylene, placed in a 1000 ml flask, 15 g of aluminum acetyl...

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Abstract

The characteristics of the invention are that the spin finish aid of the organic polymer containing one or multiple of sintering auxiliary agents is in troduced before spinning. The sintering auxiliary agent is at least one of B, Al, Y, Mg, Ti, Zr. The sintering auxiliary agent can be contained in one organic polymer or different organic polymers. The organic polymer is the polymer in silazane class and silicone carbon hydride. The method improves the spinning quality. The fiber produced can bear temperature higher than 1500 deg.C with diameter less than 10 micros, possessing good antioxidation property and mechanical property, being as the new generation of the reinforcement fiber. The method is easy to realize the continuous production.

Description

technical field [0001] The invention relates to a preparation method of high temperature resistant polycrystalline silicon carbide fiber above 1500°C. Background technique [0002] At present, SiC fibers are mostly prepared by melt-spinning, non-melting treatment and high-temperature firing with organosilicon polymer-polycarbosilane (PCS) as the precursor. However, since the air oxidation method is usually used to cross-link the fibers in the process of non-melting treatment, a large amount of oxygen is introduced into the fibers, and because PCS is a carbon-rich precursor, the final obtained Ceramic fiber is a carbon-rich, oxygen-rich non-stoichiometric SiC fiber. When the operating temperature exceeds 1200°C, impurity oxygen will escape in the form of gaseous CO or SiO, resulting in a large number of holes in the fiber due to weightlessness, rapid growth of crystal grains, and a sharp drop in strength. Therefore, its maximum operating temperature is only about 1000°C. I...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/571D01F6/76D01F9/10
Inventor 楚增勇冯春祥宋永才
Owner NAT UNIV OF DEFENSE TECH
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