Preparation method of metal-containing silicon carbide fiber

Abstract

The invention discloses a preparation method of metal-containing silicon carbide fibers, the preparation method comprises the following steps: sequentially adding alkali metal and metallocene into an organic solvent in a protective atmosphere, then dropwise adding chlorosilane, carrying out first reaction, solid-liquid separation and solvent removal to obtain a reactant B, and then carrying out second reaction on the reactant B and a reactant A in the protective atmosphere, removing the solvent to obtain polymetal carbosilane, wherein the reactant A is liquid polysilicon carbosilane; and finally, carrying out melt spinning, non-melting treatment and high-temperature treatment on the polymetal carbosilane to obtain the metal-containing silicon carbide fiber. Metal elements in the obtained polymetal carbosilane are introduced in a small molecule stage, and the uniformity of the metal elements reaches a molecular level, so that the distribution in a ceramic product is more uniform, the metal carbide phase in the finally obtained silicon carbide fiber is uniformly dispersed and distributed, the uniformly dispersed metal is more beneficial to the growth of each component, especially SiC crystal grains, and finally, the SiC fiber with excellent high-temperature performance is obtained.

Description

technical field [0001] The invention relates to a method for preparing metal-containing silicon carbide fibers, in particular to a method for preparing SiC ceramic fibers through a precursor conversion method, and belongs to the technical field of silicon carbide fiber preparation. Background technique [0002] SiC ceramic fiber is another high-performance fiber after carbon fiber. It has excellent properties such as high strength, high modulus, high temperature resistance, corrosion resistance, oxidation resistance, low density, creep resistance, and good compatibility with ceramic substrates. Due to its excellent high-temperature oxidation resistance, it has become the main reinforcing fiber for the preparation of ultra-high temperature resistant and oxidation-resistant high-performance composite materials. From the perspective of comprehensive performance such as service temperature and oxidation resistance, C f / SiC、SiC f Continuous fiber reinforced ceramic matrix compo...

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Problems solved by technology

[0003] Single-phase SiC ceramics have excellent potential for temperature resistance. In theory, pure β-SiC crystals can withstand temperatures up to 2600 °C. The highest temperature resistance of SiC fibers currently prepared is only 1600 °C. The main reason is that the current SiC fibers are not pure. When the temperature rises, the original β-SiC crystallites will get new supplements from the continuous phase and grow rapidly, and the original glassy continuous phase will become an isolation layer for large grains. Large interfacial stress is generated, which reduces the mechanical properties of SiC fibers

At present, the biggest problem that limits the performance improvement of SiC ceramics is: excessive growth of β-SiC grains at high temperatures

The main problems in the above approach are as follows: firstly, since the introduced metal elements mainly utilize the Si-H active reaction sites in polycarbosilane, the introduction amount of metal elements is limited by the Si-H content of polycarbosilane, the above-mentioned content The zirconium content in the zirconium precursor is generally below 2wt%. Secondly, because the acetylacetonate group contains relatively high oxygen and the reaction temperature is not high enough to completely remove the acetylacetonate group, etc., resulting in zirconium-containing polycarbosilane containing more High oxygen, thus affecting its subsequent application or must take corresponding measures to reduce the oxygen content

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