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A kind of preparation method of silicon carbide ceramic precursor polycarbosilane

A technology of silicon carbide ceramics and polycarbosilane, which is applied in the field of silicon carbide ceramics, can solve the problems of high raw material cost, polycarbosilane carbon-rich reactivity, and difficulty in obtaining SiC ceramics, etc., and achieve simple source, high nucleophilicity, and polymerization The effect of high reactivity

Active Publication Date: 2021-06-29
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, since the C / Si in the repeating unit is 2, it is not easy to obtain SiC ceramics with a near-stoichiometric ratio.
[0011] In summary, in the existing polycarbosilane preparation methods, there are problems such as high raw material cost, carbon-rich or low reactivity of the obtained polycarbosilane

Method used

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  • A kind of preparation method of silicon carbide ceramic precursor polycarbosilane
  • A kind of preparation method of silicon carbide ceramic precursor polycarbosilane
  • A kind of preparation method of silicon carbide ceramic precursor polycarbosilane

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Effect test

Embodiment 1

[0069] The structural formula is [SiH 2 CH 2 ] n Preparation of polycarbosilanes.

[0070] Under nitrogen protection and room temperature environment, add metal sodium (1mol) and xylene (500mL) to a four-necked flask equipped with a mechanical stirrer, a thermometer, a nitrogen inlet tube, a condenser and a dropping funnel, stir and heat up to 100°C. After the temperature was constant, chloromethyltrimethoxysilane (0.5 mol) was added in portions, and then the reaction was continued for 3 hours. After the temperature of the solution dropped to room temperature, the upper layer solution was transferred to a centrifuge tube by pouring, and then centrifuged at a high speed to remove the residual solid suspension. The solvent xylene was recovered by distillation under reduced pressure, tetrahydrofuran (500 mL) dehydrated by sodium was added to the obtained intermediate product, the temperature was raised to 40 ° C, and then the reducing agent lithium aluminum hydride (0.35 mol)...

Embodiment 2

[0076] The structural formula is {[SiH 2 CH 2 ] 9 -[SiH(CH 2 -CH=CH 2 )CH 2 ] 1} n Preparation of polycarbosilanes.

[0077] Under nitrogen protection and room temperature environment, put metal sodium (1mol), chloropropene (0.05mol), size 10~ 30nm copper powder (0.01mol), chloromethyltrimethoxysilane (0.05mol) and cyclopentyl methyl ether (500mL) were added, stirred and heated to 100°C. After the temperature was constant, chloromethyltrimethoxysilane (0.4 mol) was added in portions, and then the reaction was continued for 4 hours. After the temperature of the solution drops to room temperature, add trimethylchlorosilane (0.6mol) and stir for 0.5 hours, then extract trimethylchlorosilane and trimethyl-methoxy silane. The resulting solution was heated up to 50°C, and then the reducing agent lithium aluminum hydride (0.26 mol) was added in batches, and the reaction was continued at 60°C for 5 hours. After cooling, add in ice hydrochloric acid aqueous solution (concent...

Embodiment 3

[0083] The structural formula is {[SiH 2 CH 2 ] 9 -[SiH(CH 2 -CH=CH 2 )CH 2 ] 1} n Preparation of hyperbranched polycarbosilanes:

[0084]Under nitrogen protection and room temperature environment, put metal sodium (1mol), chloropropene (0.05mol), size 10~ 30 nm copper powder (0.05 mol) and cyclopentyl methyl ether (500 mL) were added, stirred and heated to 100°C. After the temperature became constant, a mixture of chloromethyltrimethoxysilane (0.42 mol) and tris(chloromethyl)-methoxysilane (0.01 mol) was added in batches, and the reaction was continued for 3 hours. After the temperature of the solution drops to room temperature, add trimethylchlorosilane (0.6mol) and stir for 0.5 hours, then extract trimethylchlorosilane and trimethyl-methoxy silane. The resulting solution was heated up to 50°C, and then the reducing agent lithium aluminum hydride (0.26 mol) was added in batches, and the reaction was continued at 60°C for 5 hours. After cooling, add in batches hydr...

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Abstract

The invention discloses a method for preparing silicon carbide ceramic precursor polycarbosilane, which comprises the following steps: (1) adding metal sodium into a reaction solvent, raising the temperature under stirring and gradually adding halomethyltrialkoxysilane, continuing The reaction mainly generates sodium salt, alkoxy-containing polycarbosilane and sodium alkoxide; (2) removes the sodium salt generated in step (1), adds a reducing agent after heating up, and alkoxy-containing polycarbosilane is reduced to generate Polycarbosilane products. The source of raw materials used in the preparation is simple, the polymerization activity is high, and the crosslinking group can be introduced in a variety of different ways; the prepared polycarbosilane has low viscosity and high purity, and can obtain silicon carbide with a near stoichiometric ratio after sintering ceramics.

Description

technical field [0001] The invention relates to the field of silicon carbide ceramics, in particular to a method for preparing polycarbosilane, a precursor of silicon carbide ceramics. Background technique [0002] The preparation of ceramics by precursor conversion method was founded in the mid-1970s by Verbeek of Germany and Yajima of Japan. The conversion of precursors to high-performance ceramic materials can flexibly control and improve the chemical structure, phase composition, atomic distribution and microstructure of ceramic materials, especially in the preparation of SiC, Si 3 N 4 High-performance non-oxide ceramics such as Si-C-N have incomparable advantages over traditional ceramic preparation processes, and have attracted extensive attention from academia and industry. The so-called precursor conversion method to prepare ceramics is to firstly prepare a polymer that can be converted into a ceramic material by high-temperature pyrolysis through a chemical synthe...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G77/60
CPCC08G77/60
Inventor 裴学良何流黄庆席先锋钟希强
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI