Preparation method of low-thermal-conductivity silicon-nitride-bonded silicon carbide porous ceramic

Abstract

The invention relates to a preparation method of low-thermal-conductivity silicon-nitride-bonded silicon carbide porous ceramic. The preparation process can be realized with the steps that: (1) ceramic powder, water, a dispersing agent, a monomer used in gel-casting molding, and a crosslinking agent are subjected to mixing and ball milling, such that uniform slurry is obtained; (2) a proper amount of a foaming agent is added into the slurry, and the slurry is mechanically stirred, such that foam slurry is obtained; proper amounts of an initiator and a catalyst are sequentially added into the foam slurry, and the foam slurry is rapidly casted into a mold; (3) when the slurry is cured, de-molding is carried out, such that a blank is obtained; and the blank is sequentially dried in a constant-temperature constant-humidity chamber and in a common baking oven; (4) the dried blank is sequentially subjected to de-binding in an air atmosphere furnace and sintering in a nitrogen atmosphere furnace, such that silicon-nitride-bonded silicon carbide porous ceramic is obtained. The method provided by the invention is characterized in that, with the foaming technology, enough gap space is maintained in the inside after the blank is molded; with the fiber structure produced during silicon nitridation, the prepared product has low density, ultralow thermal conductivity, and good corrosion resistance. The ceramic can be used as an energy-saving aluminum electrolysis cell periphery insulation material.

Description

technical field [0001] The present invention relates to a kind of preparation method of silicon nitride combined with silicon carbide porous ceramics with low thermal conductivity, more precisely relates to a kind of silicon / silicon carbide porous body first prepared by gel injection molding process combined with foaming method, and then treated with nitrogen The invention relates to a preparation method for finally obtaining silicon nitride combined with silicon carbide porous ceramics through chemical sintering, and belongs to the field of porous ceramics preparation. Background technique [0002] For a long time, because silicon nitride combined with silicon carbide has excellent properties such as good cryolite melt erosion resistance, good corrosion resistance, and good thermal shock resistance, it is currently the most commonly used side lining material for prebaked aluminum electrolytic cells. In recent years, due to the aggravation of the energy crisis and my country...

AI Technical Summary

Problems solved by technology

Among them, carbon blocks and silicon nitride combined with silicon carbide bricks are commonly used corrosion-resistant side lining materials in the field of aluminum electrolytic cells, but their thermal conductivity is high and heat loss is serious; aluminum silicate fiberboard has low density, low thermal conductivity, good heat preservation The effect is good, but the fiberboard is easy to react with F, Na and other substances during use, resulting in the deterioration of the fiber structure, damaging its thermal insulation performance and even causing the fiberboard to be pulverized

[0003] The current technical solution is to simply combine the corrosion resistance of carbon blocks and silicon nitride combined with silicon carbide bricks and the thermal insulation performance of aluminum silicate fiber boards to prepare composite materials, but it is still difficult to achieve both corrosion resistance and efficient thermal insulation. Effect

If the silicon nitride combined with silicon carbide material is prepared into a porous structure, it has a low thermal conductivity on the basis of excellent corrosion resistance, thus replacing the aluminum silicate fiber board will be a good solution to the existing composite materials. The problem of poor corrosion resistance

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