Porous carbon preform for reactive sintering, as well as preparation method and application thereof

A technology of porous carbon and prefabricated body, applied in the application, household appliances, ceramic products, etc., can solve the problems of uneven material density, low preparation cost, change the preparation method, etc., to achieve good reaction sintering performance, uniform pore structure, extended The effect of operating time

Active Publication Date: 2014-03-19
CHINA BUILDING MATERIALS ACAD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] At present, the methods for preparing porous carbon preforms mainly include the chemical synthesis phase separation pyrolysis method invented by Hucke (Hucke, Hucke E E. Methods of producing carbonaceous bodies and the products there of. U.S. Pat. No. 3859421, Jan. 7, 1975.), this method can precisely control the density and pore structure of the porous carbon preform, so that the porous carbon preform with uniform structure can be obtained. The flexural strength can reach 800MPa, but this method involves complex physical and chemical processes, the preparation parameters are not easy to control, the preparation cost is high, and industrial production has not been realized
[0004] The wood pyrolysis framework method is a traditional method for preparing porous carbon preforms. This method can accurately replicate the natural structure of wood and prepare porous carbon preforms with biological forms. At the same time, it does not involve complex physical and chemical reactions, and the preparation cost It is also lower than the chemical synthesis phase separation pyrolysis method invented by Hucke, but during the pyrolysis process of wood, the deformation and cracks caused by uneven material density and burning loss greatly affect the quality of porous carbon prefabricated body
[0005] Chinese patent application 00114425.1 "Method for manufacturing reaction-sintered silicon carbide ceramic mater...

Method used

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  • Porous carbon preform for reactive sintering, as well as preparation method and application thereof
  • Porous carbon preform for reactive sintering, as well as preparation method and application thereof
  • Porous carbon preform for reactive sintering, as well as preparation method and application thereof

Examples

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preparation example Construction

[0044] Specifically, the preparation method of the porous carbon preform of the present invention may include the following steps:

[0045] 1) Preparation of slurry: charcoal powder is used as carbon source, lignocellulose is used as pore-forming agent, modified polyester polymer is used as dispersant, camphene is used as dispersion medium, a certain amount of ether is added, and zirconia balls are used as ball mill Medium, constant temperature ball milling at 50-55°C (preferably 55°C) for 10-24 hours (preferably 16 hours), to obtain a slurry with good fluidity, the slurry is subjected to constant temperature vacuum at 50-55°C (preferably 55°C) Degassing to obtain a slurry that can be used for casting;

[0046] 2) Forming and sublimation: the slurry is poured and formed at room temperature, and the green body is placed on the sponge pad after forming, and sublimated in the atmospheric environment, so that the green body is sublimated to a constant weight;

[0047] 3) Bisque f...

Embodiment 2

[0073] The SEM image (1000×) of the porous carbon preform of Example 2 (comparative sample) is as Figure 5 shown by Figure 5 It can be seen that there are two kinds of pore structures inside the porous carbon prefabricated body, one is cylindrical macropores with a pore diameter of about 20 μm, this pore structure is caused by the sublimation and elimination of camphene crystals, camphene-based charcoal powder After the slurry is solidified, amphene forms dendritic crystals inside the green body, and with the sublimation and removal of the amphene crystals, pores are left inside the preform. Due to the large pore size and dense pore walls, these pores are difficult to react with silicon infiltration at high temperature. During the process, the violent reaction of carbon and silicon will cause volume expansion, and the siliconizing channel will be blocked in the hole wall, so that the molten silicon cannot penetrate into the hole wall and react with carbon, resulting in unrea...

Embodiment 1

[0074] The SEM image (1000×) of the porous carbon preform of Example 1 is as Figure 6 shown by Figure 6 It can be seen that there are only evenly distributed small pores with irregular shapes and a pore size of less than 10 μm inside the porous carbon prefabricated body. The addition of cellulose not only changes the pore structure of the porous carbon preform, but also improves the structural uniformity of the porous carbon preform. In addition, the density of the porous carbon preform of Example 1 was measured to be 0.70 g / cm 3 , the porosity is 66.7%, which meets the requirements.

[0075] 3. Preparation of reaction sintered silicon carbide by porous carbon preform through high temperature siliconizing reaction

[0076] The raw material formula and process parameters of the porous carbon preform prepared in Example 1-26 are shown in Table 2 (the serial number of Example 1-26 corresponds to the serial number of Example 1-26):

[0077] Table 2 uses the porous carbon pre...

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Abstract

The invention discloses a porous carbon preform for reactive sintering, as well as a preparation method and application thereof. The porous carbon preform is obtained by taking charcoal powder as a carbon source, taking lignocellulose as a pore-forming agent, taking a modified polyester type high molecular compound as a dispersant, taking camphene as a dispersion medium, adding a certain amount of ethyl ether, performing constant-temperature ball milling at the temperature of 55 DEG C to obtain material slurry, performing vacuum degassing, then pouring and forming the material slurry at room temperature, subliming till constant weight, and carrying out biscuit firing at the temperature of 900-1550 DEG C for 0.5-2h. The porous carbon preform prepared by the method disclosed by the invention has the advantages of controllable density and porosity, uniform pore structure, no defects and the like, and has great reactive sintering performance; reaction sintered silicon carbide generated by high-temperature silicon impregnation reaction has no black cores, cracking, delamination and other defects, and has good mechanical properties.

Description

technical field [0001] The invention relates to a porous carbon preform and its preparation method, in particular to a porous carbon preform for reaction sintering, its preparation method and its application in preparing silicon carbide. Background technique [0002] The preparation of reaction-sintered silicon carbide by impregnating porous carbon preforms with molten silicon is a very competitive technology, which has the advantages of less residual silicon, high flexural strength, and low cost. However, during the siliconizing process, the reaction between the carbon in the porous carbon preform and the molten silicon is very violent, and the porous carbon preform has a dramatic volume expansion effect during the siliconizing reaction, which easily leads to reaction sintering of silicon carbide. Defects such as black centers, cracks, and delaminations appear. Therefore, the preparation of porous carbon preforms is very important, and the density of porous carbon preforms ...

Claims

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Application Information

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IPC IPC(8): C04B38/06C04B35/52C04B35/622
Inventor 胡传奇霍艳丽王华梁海龙刘海林唐婕陈玉峰
Owner CHINA BUILDING MATERIALS ACAD
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