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Preparation method of silicon carbide fiber with boron nitride structure surface layer

A technology of silicon carbide fiber and polycarbosilane fiber, which is applied in the field of SiC fiber preparation, can solve the problems of large fiber damage, decrease in mechanical properties, weight loss of fiber, etc., and achieve the effect of improving performance, improving interface and low manufacturing cost

Active Publication Date: 2012-08-15
NAT UNIV OF DEFENSE TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The general-purpose SiC fiber is prepared by the precursor conversion method. The common problem is that the SiCxOy phase decomposes at high temperature to produce gas escape systems such as CO and SiO. The fiber loses weight significantly, forming a large number of holes and microcracks, and the grains grow rapidly. The tensile strength of the fiber is inversely proportional to the square root of the grain radius, so the mechanical properties drop sharply
However, the PIP process has greater damage to the fiber and is easy to form a strong interface bond, while the CVD process has less damage to the fiber than the PIP process, but requires special equipment, and there are many shortcomings in continuous coating and uniformity

Method used

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  • Preparation method of silicon carbide fiber with boron nitride structure surface layer
  • Preparation method of silicon carbide fiber with boron nitride structure surface layer
  • Preparation method of silicon carbide fiber with boron nitride structure surface layer

Examples

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Embodiment 1

[0020] This embodiment includes the following steps:

[0021] (1) Put the polycarbosilane in the melting cylinder of the melt spinning device, heat it to 310°C under the protection of high-purity nitrogen with a purity of 99.999% and completely melt it, then draw it at a speed of 450m / min under a pressure of 0.6MPa , to produce continuous polycarbosilane fibers with an average fiber diameter of 12 m;

[0022] (2) Place the continuous polycarbosilane fiber obtained in step (1) in a non-melting treatment device, and after vacuuming, introduce 99.999% high-purity nitrogen gas and repeat it 3 times. High-purity nitrogen gas is used as a carrier gas to blow borane into the system at a flow rate of 20ml / min / g, and continue to heat up to 300°C at a heating rate of 20°C / hour, and heat preservation treatment for 1 hour to obtain boronized fibers;

[0023] (3) Place the boronized fiber obtained in step (2) in a high-temperature furnace, and in an atmosphere of 99.999% high-purity amm...

Embodiment 2

[0027] This embodiment includes the following steps:

[0028] Step (1) is operated with embodiment 1;

[0029] (2) Place the continuous polycarbosilane fibers obtained in step (1) in a non-melting treatment device, and after vacuuming, introduce high-purity nitrogen gas with a purity of 99.999% and repeat 3 times before heating up to 120°C. Boron trichloride is used as the Active atmosphere, using high-purity nitrogen with a purity of 99.999% as the carrier gas to pass boron trichloride into the system at a flow rate of 10ml / min / g, and continue to heat up to 320°C at a heating rate of 20°C / min, heat preservation treatment 2 Hour, get boronized fiber;

[0030] (3) Place the boronized fiber obtained in step (2) in a high-temperature atmosphere furnace, under a mixed atmosphere of 40% volume ammonia and 60% volume high-purity nitrogen (high-purity nitrogen purity is 99.999%), press 60 ° C / The temperature was raised to 800°C at a speed of 1 hour, and continued to be heated to ...

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Abstract

The invention discloses a preparation method of a silicon carbide fiber with a boron nitride structure surface layer. The preparation method comprises the following steps of: 1, preparing a continuous polycarbosilane fiber through melt spinning; 2, carrying out melting-free treatment; and 3, nitriding for decarbonizing, and then sintering at high temperature. The preparation method has the advantages of simple process, convenience in implementation and low cost. The silicon carbide fiber with the boron nitride structure surface layer, prepared by the invention, has good properties of resisting high temperature and oxidization, is improved in fiber interface, and is enhanced in property of a fiber reinforced composite.

Description

technical field [0001] The invention relates to a method for preparing SiC fibers, in particular to a method for preparing silicon carbide (SiC) fibers with a surface layer of boron nitride (BN) structure. Background technique [0002] SiC fiber is an excellent functional structural material and has broad application prospects in many fields such as aerospace and atomic energy. In the early 1980s, after silicon carbide (SiC) fiber represented by Nicalon entered the high-tech field, its unique high temperature resistance (1000°C) attracted the attention of the world's technological powers. At present, Japan has realized the industrial production of SiC fiber and imposed a technical blockade on my country. In China, after more than 30 years of exploration and research, the National University of Defense Technology has independently developed a series of SiC fibers, including KD-I SiC fibers, KD-II SiC fibers, KA-SA high temperature-resistant SiC fibers and KD-X wave-absorbing...

Claims

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Application Information

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IPC IPC(8): D01F9/10D01F11/00D01D5/08D01D10/02
Inventor 邵长伟宋永才简科谢征芳王浩王军
Owner NAT UNIV OF DEFENSE TECH
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