Porous silicon carbide ceramic and preparation method thereof

A technology of porous silicon carbide and silicon carbide, which is applied in the field of materials, can solve the problems of increasing the difficulty and cost of sintering process, excessive oxidation of silicon carbide, and the decrease of bending strength, so as to avoid the decrease of ceramic strength, reduce the sintering temperature, and improve the bending resistance The effect of intensity

Inactive Publication Date: 2016-02-03
SHENZHEN SUNTECH ADVANCED CERAMICS
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  • Abstract
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  • Application Information

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Problems solved by technology

However, for porous silicon carbide ceramics, an excessively high sintering temperature will reduce the porosity and easily form closed pores. At present, the sintering temperature of porous silicon carbide ceramics is generally reduced by adding sintering aids, such as adding a low-temperature molten liquid phase. The glass-like substance can reduce the sintering temperature of porous silicon carbide ceramics to below 1500 ° C. It cannot be sintered in air at such a high temperature, otherwise it will easily lead to excessive oxidation of silicon carbide, which will reduce the bending strength of porous silicon carbide ceramics. It must be sintered under vacuum or atmosphere protection, which increases the difficulty and cost of the sintering process

Method used

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  • Porous silicon carbide ceramic and preparation method thereof

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preparation example Construction

[0022] like figure 1 Shown, the preparation method of the porous silicon carbide ceramics of an embodiment, comprises the steps:

[0023] Step S110: mixing silicon carbide, aluminum hydroxide, fumed silica, water, a dispersant and a binder to obtain a slurry.

[0024] Wherein, the sum of the mass of aluminum hydroxide and fumed white carbon black accounts for 5-30% of the sum of the mass of silicon carbide, aluminum hydroxide and fumed white carbon black.

[0025] Wherein, the molar ratio of aluminum hydroxide to fumed white carbon black is 2-5:1. Preferably, the molar ratio of aluminum hydroxide to fumed silica is 3-4:1.

[0026] Among them, gas-phase silica is generally prepared by chemical vapor deposition (also known as pyrolysis method, dry method or combustion method). Its raw materials are generally silicon tetrachloride, oxygen (or air) and hydrogen, which are reacted at high temperature. The reaction formula is: SiCl 4 +2H 2 +O 2 —> SiO2 2 +4HCl. Air and hydr...

Embodiment 1

[0047] The preparation process of the porous silicon carbide ceramic of the present embodiment is as follows:

[0048] (1) Weigh silicon carbide, aluminum hydroxide and fumed silica respectively, and put them into a ball mill jar, wherein the sum of the mass of aluminum hydroxide and fumed silica accounts for The sum of the mass of black is 5%, the molar ratio of aluminum hydroxide to fumed silica is 2:1, and the particle size of silicon carbide is 10 microns.

[0049] (2) Add the dispersant and binder to deionized water, stir and mix for 1 hour to obtain the pre-preparation solution, add the pre-preparation solution into the ball mill tank, and ball mill and mix for 20 hours at a ball milling rate of 100 rpm, Get a slurry. Wherein, the dispersant is ammonium citrate, and the quality of the dispersant is 0.5% of the sum of the mass of silicon carbide, aluminum hydroxide and fumed silica; the binder is hydroxymethyl cellulose, and the quality of the binder is It is 0.5% of th...

Embodiment 2

[0055] The preparation process of the porous silicon carbide ceramic of the present embodiment is as follows:

[0056] (1) Weigh silicon carbide, aluminum hydroxide and fumed silica respectively, and put them into a ball mill jar, wherein the sum of the mass of aluminum hydroxide and fumed silica accounts for The sum of the mass of black is 20%, the molar ratio of aluminum hydroxide to fumed silica is 4:1, and the particle size of silicon carbide is 10 microns.

[0057] (2) Add the dispersant and binder to deionized water, stir and mix for 2 hours to obtain the pre-mixed solution, add the pre-mixed solution to the ball mill tank, and ball mill and mix at a speed of 100 rpm for 30 hours to obtain slurry. Wherein, the dispersant is ammonium polyacrylate, and the quality of the dispersant is 2% of the sum of the quality of silicon carbide, aluminum hydroxide and fumed silica; the binder is hydroxymethyl cellulose, and the quality of the binder is It is 1% of the sum of the mass...

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Abstract

The invention relates to porous silicon carbide ceramic and a preparation method thereof. The preparation method comprises the following steps: mixing silicon carbide, aluminum hydroxide, fumed silica, water, a dispersant and a binder so as to obtain slurry, wherein the sum of the mass of aluminum hydroxide and fumed silica accounts for 5 to 30% of the sum of the mass of silicon carbide, aluminum hydroxide and fumed silica, and a mol ratio of aluminum hydroxide to fumed silica is 2-5: 1; drying the slurry so as to obtain mixed powder; molding the mixed powder to obtain a green body; and sintering the green body in an air atmosphere at 1310 to 1340 DEG C so as to obtain the porous silicon carbide ceramic. The preparation method can prepare the porous silicon carbide ceramic with good bending resistance at a low sintering temperature.

Description

technical field [0001] The invention relates to the field of materials, in particular to a porous silicon carbide ceramic and a preparation method thereof. Background technique [0002] Since silicon carbide is a covalent bond compound, the atomic diffusion rate is very low during sintering, so the sintering of pure silicon carbide ceramics is very difficult. The sintering temperature generally exceeds 2000 ° C, and usually requires a hot-pressing sintering process. However, for porous silicon carbide ceramics, an excessively high sintering temperature will reduce the porosity and easily form closed pores. At present, the sintering temperature of porous silicon carbide ceramics is generally reduced by adding sintering aids, such as adding a low-temperature molten liquid phase. The glass-like substance can reduce the sintering temperature of porous silicon carbide ceramics to below 1500 ° C. It cannot be sintered in air at such a high temperature, otherwise it will easily lea...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/565
Inventor 林勇钊向其军谭毅成
Owner SHENZHEN SUNTECH ADVANCED CERAMICS
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