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Preparation method of Si-C-N ceramic precursor

A technology of ceramic precursor and si-c-n, which is applied in the synthesis field of Si-C-N ceramic precursor, can solve the problems of increasing reaction procedures, difficulty in purifying polysilazane, inevitable by-product chloramine salt, etc., and achieves reaction efficiency High, diverse raw material compounds, high product purity effect

Active Publication Date: 2012-09-12
ZHEJIANG SCI-TECH UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] However, the traditional precursor synthesis method is to ammolyze chlorosilanes in organic solvents, which inevitably produces chloramine salts as by-products, which brings great difficulties to the purification of polysilazanes and increases the reaction procedure.

Method used

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  • Preparation method of Si-C-N ceramic precursor
  • Preparation method of Si-C-N ceramic precursor
  • Preparation method of Si-C-N ceramic precursor

Examples

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Embodiment 1

[0022] Dissolve 13.2g of dimethyldichlorosilane in 100mL of n-hexane to obtain oil phase solution I, dissolve 6g of ethylenediamine in 100 ml of 80g / L NaOH aqueous solution to obtain water phase solution II, drop water phase solution II to the oil In phase solution I, react at -25°C for 4 hours, heat up to 40°C, react for 8 hours, separate the liquid, and rotate the oil phase at 70°C for 1 hour to obtain 6.8 g of low-viscosity liquid polysilazane with a yield of 93%. The polysilazane was heat-treated at 50° C. for 72 hours in a vacuum atmosphere to obtain a solid precursor.

[0023] The FT-IR spectra of polysilazane and precursor are as follows figure 1 Curves a and b in. 3380-3330cm in map a -1 The absorption peak at shows that the ammonolysis of chlorosilane occurs, and the product is polysilazane.

Embodiment 2

[0025] 6.6g of dimethyldichlorosilane and 7.25g of methylvinyldichlorosilane were dissolved in 100mL of dichloromethane to obtain oil phase solution I, 13.6g of NH 3 Dissolve in 100ml of 160g / L NaOH aqueous solution to obtain water phase solution II, drop water phase solution II into oil phase solution I, react at 0°C for 4 hours, heat up to 20°C, react for 8 hours, separate liquid, rotate at 70°C The oil phase was evaporated for 1 hour to obtain 7.2 g of low-viscosity liquid polysilazane with a yield of 91%. The polysilazane in N 2 Protective heat treatment at 250°C for 12 hours to obtain a solid precursor.

[0026] The infrared spectra of polysilazane and precursor are as follows figure 2 Curves a and b in.

Embodiment 3

[0028] 14.45g of methylvinyldichlorosilane was dissolved in 100mL of xylene to obtain oil phase solution I, 15.0g of tetramethyldisilazane was dissolved in 100 ml of 112g / L KOH aqueous solution to obtain water phase solution II, and water was added dropwise Phase solution II was transferred to oil phase solution I, reacted at 0°C for 4 hours, then heated to 20°C, reacted for 8 hours, separated the liquid, and evaporated the oil phase at 100°C for 1 hour to obtain 15.7 g of viscous liquid polysilazane. Yield 90%. The polysilazane was heat-treated at 170° C. for 24 hours under the protection of Ar to obtain a solid precursor.

[0029] The infrared spectra of polysilazane and precursor are as follows image 3 Curves a and b in.

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Abstract

The invention discloses a preparation method of a Si-C-N ceramic precursor. The preparation method comprises the following steps of: dissolving silicon-containing chlorosilane in an organic solvent which in immiscible with water, carrying out ammonolysis by virtue of aqueous alkali of a compounding containing -NH-, separating oil phase from water phase, and rotatably evaporating the oil phase at the boiling temperature of the organic solvent, to obtain liquid polysilazane; and putting the liquid polysilazane in a three-opening flask, and in the presence of N2, Ar or vacuum atmosphere, and continuously carrying out curing reaction for 12-72 hours at the temperature of 50-250DEG C, wherein the obtained solid product is the Si-C-N ceramic precursor. According to the preparation method, interfacial polymerization is adopted, so that the influence of byproducts on the purification and yield of polysilazane can be avoided, the reaction working procedures can be simplified, and the reaction time can be shortened; and the reaction process is easy to control, the synthesis yield reaches up to 90%, the product is high in purity, and a pyrolysis product is good in high temperature resistance and oxidation resistance.

Description

technical field [0001] The invention relates to a synthesis method of a Si-C-N ceramic precursor, in particular to a preparation method of polysilazane. Background technique [0002] Si-C-N ceramics are widely used in the fields of information, electronics, aviation, aerospace and military for their high strength, high modulus, high hardness, low density, low thermal expansion coefficient, and excellent thermal shock resistance, oxidation resistance and chemical corrosion resistance. a wide range of applications. Since C, Si and N mainly form strong covalent bonds, the diffusion coefficients of C and Si in their nitrides are extremely low. Theoretically, it is difficult to obtain nitrogen with uniform composition and ideal properties by using traditional ceramic sintering methods. compound ceramic materials. The conversion of polymer precursors is an effective method to prepare such nitride ceramic materials. The most successful example of preparing Si-C-N ceramic materia...

Claims

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Application Information

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IPC IPC(8): C08G77/62C04B35/58
Inventor 姚菊明王元前刘琳陈建军
Owner ZHEJIANG SCI-TECH UNIV
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