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Method for preparing porous silicon carbide ceramic with high porosity

A technology of porous silicon carbide and high porosity, applied in ceramic products, applications, household appliances, etc., can solve the problems of large pore size and high reaction temperature of porous silicon carbide materials, and achieve uniform pore size distribution, high porosity, and simple process implementation Effect

Active Publication Date: 2005-11-23
TSINGHUA UNIV
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Problems solved by technology

After these raw materials are made into mud, porous silicon carbide ceramics are made through processes such as molding, drying, cracking and high-temperature sintering. The pore size, porosity and other properties can be controlled by changing the ratio of raw materials and process conditions. The reaction temperature is very high (2200~2600℃)
U.S. Patent US005248462A has also introduced a kind of silicon source and carbon source with silicon powder and carbon powder respectively, and lead ball or other spherical materials are the continuous preparation process that prepares foamed silicon carbide material as pore-forming agent, and this process is by molding (silica powder , the mixture of carbon powder and binder is evenly wrapped on the lead balls, and fills the pores between the lead balls), heating (removing the low-melting lead balls to form holes) and high temperature sintering (making silicon and carbon react to form) three steps To generate foamed silicon carbide material, but the porous silicon carbide material obtained by this method has a larger pore size

Method used

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preparation example Construction

[0012] The invention provides a method for preparing porous silicon carbide ceramics with high porosity. The method uses silicon powder (silicon source), phenolic resin (binder) and alcohol as raw materials, and undergoes inclusion mixing process, low-temperature and low-pressure molding, and high-temperature carbonization. After the four steps of treatment and high-temperature sintering, a high-porosity porous silicon carbide ceramic material is obtained, which is characterized in that: the specific process steps are:

[0013] 1) According to the mass ratio of silicon powder, phenolic resin and alcohol 1: (0.25 ~ 1.1): 2 mixed into a slurry;

[0014] 2) Preparation of entrapped powder: heat-treat the mixed slurry at 30-80°C, and stir for 30-120 minutes; then cool down to below 10°C, then cold-treat in the range of 0-10°C, and stir for 10-60 minutes at the same time; The mixed slurry is injected into water with an injection pressure of 0.2-1.2MPa; aging treatment is carried ou...

Embodiment 1

[0021] First, mix silicon powder, barium phenolic resin and alcohol (mass ratio 1:0.25:2) by inclusion mixing process, heat treatment at 30°C for 120 minutes, cold treatment at 0°C for 10 minutes, injection pressure 0.2MPa, aging treatment at 30°C for 120 minutes, Vacuum dry at 40°C for 120min to obtain inclusion-blending powder; then heat-preserve the inclusion-blending powder at 60°C and 0.05MPa pressure for 120min to obtain a ceramic green body; High-temperature carbonization treatment, the temperature is 600°C, the heating rate is 0.3°C / min, and the heat preservation is 240min; finally, the powder obtained by the carbonization treatment is subjected to high-temperature sintering under the protection of argon (50ml / min), the temperature is 1300°C, and the heating rate is 1°C / min, heat preservation for 8 hours to form a high-porosity porous silicon carbide ceramic material.

Embodiment 2

[0023] First, mix silicon powder, barium phenolic resin and alcohol (mass ratio 1:0.25:2) by inclusion mixing process, heat treatment at 30°C for 120 minutes, cold treatment at 0°C for 10 minutes, injection pressure 0.2MPa, aging treatment at 30°C for 120 minutes, Vacuum dry at 40°C for 120min to obtain inclusion-blending powder; then heat-preserve the inclusion-blending powder at 80°C and 0.1MPa pressure for 60min to obtain a ceramic green body; High-temperature carbonization treatment, the temperature is 800°C, the heating rate is 0.5°C / min, and the heat preservation is 120min; finally, the powder obtained by the carbonization treatment is subjected to high-temperature sintering under the protection of argon (100ml / min), the temperature is 1500°C, and the heating rate is 2.5°C / min, heat preservation for 4 hours to form a high-porosity porous silicon carbide ceramic material.

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Abstract

The invention discloses a method for preparing porous silicon carbide ceramic with high porosity which comprises preparing mix-coated powder from silicon powder, phenol resin and ethanol by a predetermined proportion, then carrying out low-temperature low-pressure modeling to produce ceramic blanks, high temperature carbonizing the ceramic blanks, finally sintering at high temperature to obtain the end product whose factor of porosity is greater than 80%.

Description

technical field [0001] The invention belongs to the technical field of ceramic material preparation, in particular to a method for preparing silicon carbide ceramics with high porosity. technical background [0002] Porous silicon carbide materials have been Widely used in aerospace, energy, machinery, metallurgy, chemical industry, environmental protection, military industry, electronics and biology and other disciplines, involving fluid separation and filtration, diffusion, heat insulation, sound absorption, sensing, electrochemical process and catalytic reaction engineering It can be used to make filters, separation and catalyst supports, etc. Therefore, the research on porous silicon carbide materials has attracted great attention from the global material science community, new preparation methods have emerged, and the preparation system has been continuously improved. [0003] The preparation of porous silicon carbide also has bibliographical reports, and Chinese paten...

Claims

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Application Information

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IPC IPC(8): C04B35/584
Inventor 时利民赵宏生唐春和闫迎辉梁彤祥
Owner TSINGHUA UNIV
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