Preparation method of self-setting silicon nitride foamed ceramic

Abstract

The invention discloses a preparation method of self-setting silicon nitride foamed ceramic, and belongs to the technical field of advanced ceramics. The method comprises the following steps: 1) preparing inorganic continuous long fibers into chopped fibers, and obtaining a fibrofelt with a certain shape, thickness and fiber volume fraction by using felt making equipment; 2) putting the mixed micro powder of silicon powder and silicon nitride into a solvent, adding a surfactant and a binder, and carrying out ball milling to obtain silicon-containing slurry; 3) placing the fiber felt in the silicon-containing slurry, fully impregnating the fiber felt with the silicon-containing slurry under the action of pressure, taking out the fiber felt, and drying the fiber felt to obtain a slurry hanging product; 4) placing the slurry hanging product in nitrogen or nitrogen-hydrogen mixed atmosphere, nitriding the silicon powder at high temperature to generate silicon nitride, and realizing reactive sintering in the continuous conversion process of the silicon nitride to obtain fiber-reinforced silicon nitride foamed ceramic; and 5) placing the silicon nitride foamed ceramics in the silicon-containing slurry, and repeating the steps 3) and 4) to obtain the self-setting silicon nitride foamed ceramics with different pore sizes and porosities. Micropores and microcracks are few, the junction temperature is low, and the shrinkage rate is small.

Description

technical field

[0001] The invention belongs to the technical field of advanced ceramics, in particular to a preparation method of self-setting silicon nitride foam ceramics. Background technique

[0002] Silicon nitride foam ceramics is a porous ceramic material with low density, low thermal conductivity, low thermal expansion coefficient, good high temperature stability, good thermal shock resistance, etc. It is mainly used in thermal protection, molten metal filtration, separation membrane and Catalyst carrier and other fields. At present, the preparation methods of silicon nitride foam ceramics include organic template method, foaming method and so on. The organic template method is to use porous organic materials (mostly polyurethane sponge) as a template to make silicon nitride ceramic slurry adhere to the organic porous membrane plate, and then remove the template by heat treatment. After the ceramic slurry is solidified and sintered, the shape of the template is ret...