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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 polycarbosilane carbon-rich reactivity, high raw material cost, and difficulty in obtaining SiC ceramics, etc.

Active Publication Date: 2019-02-15
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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  • Preparation method of silicon carbide ceramic precursor polycarbosilane
  • Preparation method of silicon carbide ceramic precursor polycarbosilane
  • Preparation method of silicon carbide ceramic precursor polycarbosilane

Examples

Experimental program
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Embodiment 1

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

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

Embodiment 2

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

[0077] Under the protection of nitrogen and room temperature, in a four-necked flask equipped with a mechanical stirrer, thermometer, nitrogen introduction tube, condenser and dropping funnel, add sodium metal (1mol), chloropropylene (0.05mol), size 10~ 30nm copper powder (0.01mol), chloromethyltrimethoxysilane (0.05mol) and cyclopentylmethyl ether (500mL) were added, stirred and heated to 100°C. After the temperature became constant, chloromethyltrimethoxysilane (0.4 mol) was added in batches, 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, and then extract trimethylchlorosilane and trimethylmonomethoxy at 35℃ through a circulating water pump (vacuum degree of 0.095MPa) Silane. The resulting solution was heated to 50°C, and then the reduc...

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 polycarbosilane:

[0084] Under the protection of nitrogen and room temperature, in a four-necked flask equipped with a mechanical stirrer, thermometer, nitrogen introduction tube, condenser and dropping funnel, add sodium metal (1mol), chloropropylene (0.05mol), size 10~ 30nm copper powder (0.05mol) and cyclopentyl methyl ether (500mL) were added, stirred and heated to 100°C. After the temperature is constant, a mixture of chloromethyltrimethoxysilane (0.42mol) and tris(chloromethyl)monomethoxysilane (0.01mol) is added in batches, and then the reaction is continued for 3 hours. After the temperature of the solution drops to room temperature, add trimethylchlorosilane (0.6mol) and stir for 0.5 hours, and then extract trimethylchlorosilane and trimethylmonomethoxy at 35℃ through a circulating water pump (vacuum degree of 0.095MPa) Silane. The resulting solution was he...

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Abstract

The invention discloses a preparation method of silicon carbide ceramic precursor polycarbosilane. The method comprises the following steps: (1) adding sodium metal into a reaction solvent, heating upunder stirring and gradually adding halomethyltrialkoxysilane to continue the reaction so as to mainly produce sodium salt, alkoxy-containing polycarbosilane and sodium alkoxide; (2) removing the sodium salt produced in the step (1), adding a reducing agent after heating up, and reducing the alkoxy-containing polycarbosilane to produce a polycarbosilane product. Raw materials used in the preparation are simple in source and high in polymerization activity, and can introduce crosslinking groups through a plurality of different ways; and the obtained polycarbosilane has low viscosity and high purity, and can obtain silicon carbide ceramics with near-stoichiometric ratios after sintering.

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 precursor transformation method to prepare ceramics was founded by Verbeek in Germany and Yajima in Japan in the mid-1970s. The precursor conversion of 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 and other high-performance non-oxide ceramics have advantages unmatched by traditional ceramic preparation processes, and have received widespread attention from academia and industry. The so-called precursor conversion method to prepare ceramics is to first prepare a polymer that can be converted into ceramic materials by high-temperature pyrolysis t...

Claims

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Application Information

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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
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