Preparation method of polyaluminocarbosilane

Abstract

The invention provides a preparation method of polyaluminocarbosilane, which comprises the following steps: synthesizing a first raw material containing Si(Z)a, a is 2 or 3, and Z is -C=C and / or -C-C=C; adding a certain amount of a catalyst into the first raw material and a second raw material, and performing olefin metathesis reaction to obtain a first intermediate product, the second raw material containing (X)nSi(Y)m; wherein X is CH2=CH-CH2- or CH2=CH-, and Y is at least one of Cl, Br, I and alkoxy; adding a reducing agent into the first intermediate product, reducing Y into hydrogen atomsby the reducing agent, and removing solids in the first intermediate product to obtain a second intermediate product; and finally, reacting the second intermediate product with an aluminum-containingcompound to obtain the polyaluminocarbosilane. The polyaluminocarbosilane has high-content silicon-hydrogen bonds and high-content aluminum elements, and the content of the silicon-hydrogen bonds andthe content of the aluminum elements are adjustable and controllable.

Description

technical field [0001] The invention belongs to the field of silicon carbide ceramics, in particular to a preparation method of polyaluminocarbosilane. Background technique [0002] As the precursor of the third-generation silicon carbide fiber, polyaluminocarbosilane has attracted the attention of researchers at home and abroad, and has been mass-produced as the precursor of the third-generation silicon carbide fiber. The introduction of aluminum can inhibit the crystallization of silicon carbide under high temperature conditions, which is the key to the successful preparation of aluminum-containing third-generation silicon carbide fibers. [0003] However, polyaluminocarbosilane has a single synthesis route, which is prepared by reacting silicon-hydrogen bonds in the pyrolysis product of polydimethylsilane with aluminum-containing compounds: whether it is normal pressure reaction, high pressure reaction, or polysilane as the reaction raw material, Still using low-molecula...

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Problems solved by technology

[0003] However, polyaluminocarbosilane has a single synthesis route, which is prepared by reacting silicon-hydrogen bonds in the pyrolysis product of polydimethylsilane with aluminum-containing compounds: whether it is normal pressure reaction, high pressure reaction, or polysilane as the reaction raw material, Still using low-molecular-weight polycarbosilane as the reaction raw material cannot escape the disadvantages of polydimethylsilane: there is only one active group, which is a silicon-hydrogen bond, and the silicon-hydrogen content is too low. It is synthesized from polydimethylsilane In polycarbosilane, the silicon-hydrogen bond content measured by chemical methods is 0.7-0.8%, while the theoretical silicon-hydrogen bond content is 1.72%, and the actual measured value is far lower than the theoretical value (Song Maili, Fu Likun. SiC precursor—— Application research progress of polycarbosilane[J]. China Materials Progress, 2013, 032(004):243-248.)

[0004] More problems have been plagued by the application of polyaluminocarbosilane. When the aluminum element compound is fed at a high ratio, the silicon hydrogen content is further reduced, the reactivity of polyaluminocarbosilane is lower, and it is found that a large amount of aluminum element ligands will remain, resulting in The decrease in the yield of the product ceramics, unstable properties, and poor spinning performance make it difficult to prepare and apply polyaluminocarbosilane with high aluminum content (Yuan Qin, Song Yongcai. Si(Al)C fiber precursor polyaluminocarbosilane Synthesis of [J].Journal of National University of Defense Technology,2017,39(001):182-188.)

[0005] In conclusion, the existing polyaluminocarbosilane has low silicon hydrogen content, and it is difficult to prepare polyaluminocarbosilane with high aluminum content and high aluminum content with certain silicon hydrogen reactivity

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