Method for preparing silicon nitride foam ceramic

Abstract

The invention provides a method for preparing silicon nitride foam ceramic. The method comprises raw material proportioning, raw material blending, pH adjustment, foaming molding curing and sintering. Through utilization of a carboxymethyl cellulose aqueous solution as a binder, foam system surface tension is reduced; slurry viscoelasticity is improved; foam slurry fluidity and stability are improved; a shrinking percentage in foam drying is low; a yield is high; foam stability is good; foam pore sizes are small; sintered body mechanical properties are excellent; and foam pore distribution is uniform. Through a direct mechanical stirring foaming technology, the silicon nitride foam ceramic having good foam stability and excellent mechanical properties is prepared, wherein under the premise of equal porosity, compared with silicon nitride foam ceramic prepared by the prior art, the silicon nitride foam ceramic provided by the invention has bending strength improved by 10 to 30%, and the silicon nitride foam ceramic has porosity more than 60%.

Description

technical field [0001] The invention relates to a method for preparing silicon nitride foam ceramics, which belongs to the technical field of foam ceramics. Background technique [0002] Foam ceramics is the third generation of porous ceramics developed after porous ceramics and honeycomb ceramics. It is a porous ceramic product with a three-dimensional network skeleton and interconnected or closed pore structure. In addition to excellent properties such as high temperature resistance and corrosion resistance, foam ceramics also have low density (0.25-0.65g / cm 3 ), high porosity (60% ~ 90%), large specific surface area (10m 2 / g) and strong self-disturbance to fluids, it can be used as a high-performance green environmental protection material, and has been widely used in purification and separation, chemical catalyst carriers, advanced insulation materials and sensor materials, and has attracted great attention from material scientists. [0003] The preparation methods of...

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Problems solved by technology

Geng Haoran of Shandong University, Pu Xipeng of Liaocheng University, and Zhang Wu of Ningbo Ordnance Science Research Institute prepared silicon nitride foam ceramics by organic foam impregnation process. In the process of slurry configuration, silica sol was used as binder, carboxymethyl fiber CMC is used as a slurry rheology modifier to improve the performance of foam slurry. The prepared silicon nitride foam ceramics have large pore size (≥200μm), low strength, and difficult to control the uniformity of pore distribution and pore size.

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