Process of preparing porous ceramic material by ''freezing-gel forming''

A porous ceramic and gel technology, applied in the field of ceramic materials, can solve the problems of not preparing special porous ceramic materials, and achieve excellent mechanical properties, easy process conditions, and a wide range of systems

Inactive Publication Date: 2007-10-17
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] According to the search, there is no report on the combination of cryogenic molding and h

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Example 1: Ceramic components with high open porosity

[0024] At a temperature of 25°C, the acrylamide monomer, methylene bisacrylamide and tert-butanol were mixed according to the mass ratio of 14.5:0.5:85 to prepare a pre-prepared solution, and the dispersant citric acid (citric acid and alumina The mass ratio of the solution is 1:100), and at the same time, the pH value of the solution is adjusted to 3 with glacial acetic acid; the submicron alumina powder is added according to the solid phase volume fraction of 10 vol%, and ball milled for 24 hours under the condition of 25-30°C, A stable ceramic suspension is obtained. Add mass fraction to the suspension and be 40% ammonium persulfate aqueous solution, the consumption of ammonium persulfate is 4% of the total weight of the suspension, pour into the mould after stirring evenly; Place the suspension together with the mold in the freezer (5°C) ), the tert-butanol in the suspension will freeze and crystallize from th...

Embodiment 2

[0026] Example 2: Ceramic components with high closed porosity

[0027]At a temperature of 25°C, acrylamide monomer, methylene bisacrylamide, tert-butanol and glycerol were mixed and prepared according to a mass ratio of 14.5:0.5:80:5 to form a pre-prepared solution, and a dispersant citric acid (citric acid The mass ratio of alumina to alumina is 1:100), and the pH value of the solution is adjusted to 3 with glacial acetic acid; the submicron alumina powder is added according to the solid phase volume fraction of 30vol%, and ball milled at 25-30°C for 24 hours, a stable ceramic suspension was obtained; the suspension was magnetically stirred for 20 min under vacuum conditions to remove bubbles. Adding mass fraction in the suspension is the ammonium persulfate aqueous solution of 40%, and the ammonium persulfate consumption is 4% of the suspension gross weight, pours into mold after stirring; The mold is then placed in the freezer of the refrigerator together with the insulati...

Embodiment 3

[0029] Embodiment 3: Oriented through-hole ceramic component

[0030] The preparation of the suspension is similar to "Example 1", and the solid phase content of alumina in the suspension is 20 vol%. Stir the suspension added with the ammonium persulfate initiator evenly and pour it into a mold with insulation on three sides and an open top, and then place the mold together with the insulation layer in the freezer of the refrigerator (about -20°C). The tert-butanol in the sample will freeze and crystallize from the top, so as to achieve directional growth in the entire sample. The process of freezing and forming pores is usually completed within 30 minutes. The subsequent demoulding, heat treatment, gel curing, drying, debinding, sintering and other processes are similar to "Example 1", the overall porosity of the finally obtained porous ceramic is about 75%, and more than 95% of the pores are oriented through structures .

[0031] The solvent used can also be deionized wate...

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Abstract

The present invention discloses a 'freezing-gelling molding' process for preparing a porous ceramic material and belongs to the field of ceramic materials. By combining low temperature freezing molding with heat induced gelling solidification molding of ceramic materials and adopting macromolecule polymers, solvents, initiators or chelating agents as well as ceramic powders as raw materials, saidprocess prepares a suspension containing a certain solid phase volume; by adopting a quick continuous heat processing course of 'crystallization melting-gelling solidification-solvent vaporization hole formation' performed inwards from blanks surfaces to obtain ceramic bodies with a microstructure of a frozen sample maintained therein, wherein the appearance of the pores is similar to that of solvents in crystallization state, then a ceramic material having a variety of porous structures and exhibiting excellent mechanical properties is obtained. The process conditions of the present invention is easy to realize, the suitable material system range is broad, and then the process is suitable of a plurality of purposes, such as filters used in high temperature conditions and catalyzer carrier and the like.

Description

technical field [0001] The invention relates to the field of ceramic materials and provides a process for preparing porous ceramic materials by "freezing-gel forming". Background technique [0002] Ceramic materials have outstanding characteristics such as high temperature resistance, corrosion resistance, high strength, and high hardness. Among them, ceramic materials with special pore structures (special porous ceramics) have further special functions. For example, ceramic materials with high closed porosity have high specific strength and low density, and are suitable as high-temperature heat insulation materials; ceramic materials with high open porosity have a developed specific surface area, and are suitable as filters; ceramic materials with ordered directional through holes have The long-range and orderly through-pore structure can be used as a catalyst carrier; the content and size of the pores in the gradient pore ceramic material are distributed in a gradient, and...

Claims

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Application Information

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IPC IPC(8): C04B38/06C04B38/00
Inventor 黄勇陈瑞峰汪长安林伟渊
Owner TSINGHUA UNIV
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