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Method of preparing porous ceramic through low-temperature sintering

A technology of porous ceramics and low-temperature sintering, applied in the field of porous ceramics, can solve the problems of insufficient ceramic strength, decreased pore permeability, complicated preparation process, etc., and achieve the effects of easy industrialization, high ceramic strength, and simple process.

Active Publication Date: 2016-08-31
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In 1997, Journal of the European Ceramic Society impurity described in volume 17, pages 1459-1465, the method of coating alumina particles with boehmite sol to reduce the firing temperature of ceramics. This method avoids the clogging of pores, but the oxidation Microcrystalline alumina particles generated by pyrolysis of aluminum sol are difficult to sinter and compact at the sintering neck of raw material particles, forming a loose porous structure and insufficient ceramic strength; moreover, alumina sol particles bring large specific surface area to porous ceramics, increasing Increases the frictional resistance in the fluid flow and reduces the permeability of the pores; in addition, pre-coating the particles makes the preparation process cumbersome, which is not conducive to industrialization
[0005] In short, there are many ways to reduce the sintering temperature of porous ceramics, but it is difficult to meet the requirements of simplicity without affecting the pore structure characteristics.

Method used

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preparation example Construction

[0027] The preparation process of the present invention will be further described below in conjunction with the drawings.

[0028] The flow chart of encapsulation-injection molding to prepare porous ceramics is attached figure 1 Shown:

[0029] (1) Dissolve the injection molding reagent in a silica sol solution with a concentration of 5-20wt.%, wherein the concentration of the organic monomer in the liquid phase is 2-20wt.%, and the mass ratio of MBAM to organic monomer is 1: 30-1:10, (NH 4 ) 2 S 2 O 4 3-10% of the organic monomer mass fraction, TEMED and (NH 4 ) 2 S 2 O 4 The mass ratio is 1:1-1:6.

[0030] (2) Then, the ceramic powder is mixed with the liquid premix, the powder volume fraction is 50 vol%, and the particles are uniformly dispersed through mechanical stirring. During the stirring process, adjust the pH of the solution to a set value, and then continue stirring for 10 minutes to complete the coating process.

[0031] (3) The slurry is injected into the mold, and the c...

Embodiment 1

[0036] In a silica sol solution with a concentration of 5wt.%, injection molding reagent is added. The composition of the reagent is 2wt.% of organic monomer, and the mass ratio of MBAM to organic monomer is 1:30, (NH 4 ) 2 S 2 O 4 Accounting for 3% of the mass fraction of organic monomer, (NH 4 ) 2 S 2 O 4 The mass ratio with TEMED polyol is 1:1, and the mixture is prepared. Add the alumina powder to the premixed liquid, stir and disperse and adjust the slurry pH to 3 to complete the coating process. After the slurry was injected into the mold, the particles were piled up to make holes, and then placed at 80°C, and the polymerization reaction time was 10 minutes. After the green body is dried, it is sintered at 1300°C for 2 hours to obtain a porous ceramic with a porosity of 40% and a strength of 30MPa.

Embodiment 2

[0038] In a silica sol solution with a concentration of 15wt.%, injection molding reagent is added, the composition of the reagent is 10wt.% of organic monomer, and the mass ratio of MBAM to organic monomer is 1:20, (NH 4 ) 2 S 2 O 4 Accounting for 7% of the mass fraction of organic monomers, (NH 4 ) 2 S 2 O 4 The mass ratio to TEMED polyol is 1:3, and the mixed solution is configured. Add the alumina powder to the premixed liquid, stir and disperse and adjust the slurry pH to 3 to complete the coating process. After the slurry is injected into the mold, the particles are piled up to make holes, and then placed at 50°C, and the polymerization reaction time is 40 minutes. After the green body is dried, it is sintered at 1300°C for 2h to obtain a porous ceramic with a porosity of 39% and a strength of 35MPa.

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Abstract

The invention discloses a method of preparing porous ceramic through low-temperature sintering. In the invention, a method of coating ceramic particles with silicon sol is employed to achieve surface modification of the particles, so that a ceramic powder, which is difficult to sinter, can be subjected to surface fusion at a low temperature, thereby promoting sintering mass transmission among the particles and forming a high-strength neck part. A typical preparation method includes the steps of: 1) dissolving a gel-casting reagent, comprising an organic monomer, MBAM, (NH4)2S2O4 and TEMED in the silicon sol having certain concentration to prepare a pre-mixed liquid; 2) adding raw material particles to the pre-mixed liquid, and controlling the pH to coat the particles; 3) performing stacked pore forming to the particles, and performing polymerization and curing through a reaction at a certain temperature to form a green body; and 4) drying and low-temperature-sintering the green body to form the porous ceramic. The low-temperature ceramic sintering technology not only is free of damage on pore structures but also is simple in process. The porous ceramic can be used in the field of high temperature separation.

Description

Technical field [0001] The invention belongs to the technical field of porous ceramics and relates to a method for preparing porous ceramics by low-temperature sintering. Background technique [0002] In today's era, porous ceramic materials have penetrated into many fields. Many scientific fields such as environmental protection, energy saving, chemical industry, petroleum, smelting, food, pharmaceuticals, biomedicine, etc. are inseparable from porous ceramic materials, especially in filtration, sound absorption, electrode materials, Catalysis, heat insulation, biological materials, etc. have an irreplaceable role. [0003] For high temperature resistant porous ceramics, the material is like Al 2 O 3 , SiC, Si 3 N 4 , AlN, etc., have a wide range of applications in aviation, aerospace and other fields, but the firing temperature of these ceramics is very high (> 1600°C) undoubtedly puts forward higher requirements on sintering equipment and preparation conditions, and also incr...

Claims

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Application Information

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IPC IPC(8): C04B38/00C04B35/10C04B35/628
CPCC04B35/10C04B35/628C04B38/00C04B2235/6022
Inventor 袁方利孙志强
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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