Preparation method of polymetal carbosilane precursor

Abstract

The invention discloses a preparation method of a polymetal carbosilane precursor, which 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 to obtain the polymetal carbosilane precursor. And removing the solvent to obtain polymetal carbosilane, wherein the reactant A is liquid polysilicon carbosilane. According to the preparation method, a large amount of metal is introduced through the reaction of chlorosilane and metallocene, a reactant B which has high reaction activity and contains more Si-Si bonds is obtained at the same time, then the reactant B continues to react with liquid polysilicocarbosilane, and the obtained product has high metal content and good performance stability at the same time. And the distribution of metal elements is uniform, the metal content is adjustable, and the precursor does not contain oxygen.

Description

technical field [0001] The invention relates to a method for preparing a polymetallocarbosilane precursor, and belongs to the technical field of ceramic precursor 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 composites represented by / SiC are the preferred materials for ultra-high temperature working parts. At present...

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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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