Method for preparing mullite porous ceramics by freeze-drying method

Abstract

The invention relates to a method for preparing mullite porous ceramics by a freeze-drying method. The method comprises the following steps: (1) adding modified opoka, alpha-alumina and sintering aidsinto an agate jar, and ball milling at a rate of 300 revolutions per minute for 2 hours by using a planetary ball mill so as to obtain uniformly mixed powder; (2) mixing the uniform powder and water,and preparing ceramic slurry having the starch content of 6-10 vol%; (3) rapidly pouring the prepared ceramic slurry into a mold of a certain shape for casting and molding, performing vacuum degassing, removing bubbles in the slurry, placing the sample in a cryogenic refrigerator, enabling the sample to be completely frozen, and demolding; (4) performing freeze drying on the sample in a vacuum freeze drier at the temperature of 30 DEG C below zero at a vacuum degree of 10 Pa for 36 hours; (5) sintering, and cooling, thereby obtaining the mullite porous ceramics. According to the method disclosed by the invention, the opoka serves as the main ingredient and a pore forming material, so that the void ratio of the mullite ceramics can be effectively improved, the usage amount of the adhesiveis reduced, and the strength of the product is further improved.

Description

technical field

[0001] The invention relates to a method for preparing mullite porous ceramics by a freeze-drying method, belonging to the field of inorganic ceramic materials. Background technique

[0002] Due to its good chemical stability, high strength at room temperature and high temperature, excellent thermal shock resistance and good fluid permeability, mullite porous ceramics are widely used in hot gas filtration, molten metal filtration, catalyst carrier and thermal insulation. Show broad application prospects. Different raw materials have an important influence on the microstructure, phase composition and properties of the formed acicular mullite. Influence of pore-forming agent on mullite pores In the production process of mullite foam ceramics, the method of adding pore-forming agent is more common. The pore-forming agent burns off during the sintering process of mullite, leaving a large number of pores. Authorized notification number CN101037345B, invention n...