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Preparation method for high-temperature-resistance high-crystallized near-stoichiometric-ratio continuous SiC fiber

A near-stoichiometric, high-crystalline technology, applied in the chemical characteristics of fibers, textiles and papermaking, etc., can solve the problems that the preparation method cannot amplify the preparation cost, the continuous SiC fiber has small crystal grains, and has a loose structure, and achieves easy industrial production. The effect of reducing production costs and simple equipment

Active Publication Date: 2017-12-01
NAT UNIV OF DEFENSE TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0009] The purpose of the present invention is to provide a method for preparing continuous SiC fibers with high temperature resistance and high crystallization near stoichiometric ratio, which solves the problem of small grain size, loose structure and poor compactness of the continuous SiC fibers prepared in the prior art; Technical problems such as the existing preparation method cannot be scaled up or the preparation cost is too high

Method used

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  • Preparation method for high-temperature-resistance high-crystallized near-stoichiometric-ratio continuous SiC fiber
  • Preparation method for high-temperature-resistance high-crystallized near-stoichiometric-ratio continuous SiC fiber
  • Preparation method for high-temperature-resistance high-crystallized near-stoichiometric-ratio continuous SiC fiber

Examples

Experimental program
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Effect test

Embodiment 1

[0044] (1) Add 500g of polysilane and 5g of zirconium chloride (1%) into a three-necked flask, react at a cracking temperature of 500°C and a synthesis temperature of 460°C for 8 hours, cool naturally to normal temperature to become solid, and use 500mL xylene Dissolve, remove insolubles by filtration, place the filtrate in a three-necked flask, and distill under reduced pressure at 350°C for 1 hour to obtain 200g of zirconium-containing precursor polymer with a softening point of 196°C and a number average molecular weight of 2.72×10 3 g / mol, the molecular weight distribution coefficient is 3.65.

[0045] (2) Place the zirconium-containing precursor polymer in the melting drum of the melt spinning device, heat it up to 350°C under the protection of an inert atmosphere, and wait until it is completely melted to become a uniform melt, then heat it at 280°C and a pressure of 0.5MPa , Draw spinning at a speed of 410m / min to obtain fibrils with an average diameter of 14um and a co...

Embodiment 2

[0049] Place the fibrils obtained in steps (1) and (2) of Example 1 in an air non-melting treatment device for non-melting treatment, then raise the temperature to 450 ° C at a heating rate of 5 ° C / hour, and drop to room temperature after 18 hours of heat preservation , and put the fiber in another non-melting furnace, and replace it with nitrogen for three times, feed the mixed gas of borane and nitrogen, the volume ratio of borane is 50%, rise to 450°C at a heating rate of 50°C / hour and keep it For 0.5 hours, non-melting fibers were obtained with an oxygen content of 5%.

[0050] Put the non-melting fiber in the graphite furnace, pass in nitrogen for protection, raise the temperature to 1200°C at a rate of 50°C / hour, change the atmosphere to argon after holding for 1 hour, and then increase the temperature to 1200°C at a rate of 200°C / hour 1600°C, heat preservation for 1 hour, and Si-C-O-Zr fibers were prepared after cooling. The temperature of the tubular graphite furna...

Embodiment 3

[0053] (1) Dissolve 500g of polycarbosilane in 500mL of xylene, add it to the reactor, then add 50g of aluminum acetylacetonate (10%) into the reactor, react at 300°C for 10 hours, cool naturally to room temperature and become solid , dissolved with 800mL xylene, filtered to remove insoluble matter, put the filtrate in a three-necked flask, and distilled under reduced pressure at 360°C for 3 hours to obtain 512g of aluminum-containing precursor polymer with a softening point of 221°C and a number average molecular weight of 7.02 ×10 3 g / mol, and the molecular weight distribution coefficient is 2.38.

[0054](2) Put the aluminum-containing precursor polymer in the melting cylinder of the melt spinning device, heat it up to 372°C under the protection of an inert atmosphere, and wait until it is completely melted to form a uniform melt, then heat it at 348°C and a pressure of 0.3MPa , Draw spinning at a speed of 450m / min to obtain fibrils with an average diameter of 13um and a c...

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Abstract

The invention provides a preparation method for high-temperature-resistance high-crystallized near-stoichiometric-ratio continuous SiC fiber. The preparation method comprises the steps: 1) enabling a polycarbosilane polymer to react with heterogeneous element compound to prepare a precursor and then spinning the precursor to obtain continuous fibril; 2) presintering and sintering the continuous fibril after the continuous fibril is treated in a non-melting mode to obtain the high-temperature-resistance high-crystallized near-stoichiometric-ratio continuous SiC fiber. According to the preparation method, heterogeneous elements are introduced into fiber in a precursor synthesizing process, and then boride is introduced into the fiber in non-melting or high-temperature presintering and sintering processes; a synergistic effect between the heterogeneous elements and the boride is utilized, so that SiC fiber crystal grains can rapidly grow under presintering and sintering high-temperature environment, meanwhile the SiC fiber is prevented from generating a loose and porous structure, and densification is achieved; thus, the dense high-crystallized near-stoichiometric-ratio continuous SiC fiber is obtained.

Description

technical field [0001] The invention relates to the technical field of continuous SiC fibers, in particular to a method for preparing continuous SiC fibers with high crystallization near stoichiometric ratio. Background technique [0002] Due to its excellent properties such as high strength, high modulus, high temperature resistance, oxidation resistance, corrosion resistance, creep resistance, and wear resistance, continuous SiC fibers have important application prospects in high-tech fields such as aerospace and weaponry. Theoretically, carbon and silicon elements are sp3 hybridized to form a covalent bond to form a SiC crystal with a diamond structure, and the temperature resistance of pure β-SiC crystals can be as high as 2600 °C. However, the temperature resistance of the existing SiC fibers is far below this theoretical temperature. The fundamental reason is that the SiC fibers prepared by the precursor conversion method are not composed of pure β-SiC crystals. Take ...

Claims

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Application Information

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IPC IPC(8): D01F9/10
Inventor 苟燕子王军王浩简科
Owner NAT UNIV OF DEFENSE TECH
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