Cement-free in-situ silicon nitride combined silicon carbide prefabricated member and preparation method thereof

Abstract

The invention discloses a cement-free in-situ silicon nitride combined silicon carbide prefabricated member and a preparation method thereof. The cement-free in-situ silicon nitride combined silicon carbide prefabricated member is formed by taking silicon carbide, metallic silicon powder, alumina micro powder, silicon dioxide micro powder and hydraulic alumina as materials and additionally adding dispersing agent, water or silica sol. The prefabricated member is formed by adopting a vibration pouring method, is cured and dried and subjected to high-temperature nitrogen treatment in a high-purity flowing nitrogen gas. The prefabricated member has the advantages of easy construction, low cost, flexible product shape, high hot strength, strong corrosion resistance, high wear resistance and the like and is widely applied to parts strictly requiring the hot-state performance, such as a wind-force pipeline of a cement kiln, a blast-furnace throat, an air port, a delivery pipeline of melt metal, a garbage incinerator and the like.

Description

technical field [0001] The invention relates to a silicon carbide prefabricated part used in the industrial high temperature field, in particular to a cement-free in-situ silicon nitride bonded silicon carbide prefabricated part and a preparation method. Background technique [0002] At present, the materials used in wind pipes of cement kilns, blast furnace throats and tuyeres, molten metal conveying pipes and structural components with complex shapes are mainly corundum-based materials and nitride-bonded silicon carbide-based refractory materials. These materials have the following disadvantages: (1) cement is used as one of the components of the bonding system. Since cement contains calcium salts, in aluminum-silicon refractory materials, calcium compounds will form low melting point phases at high temperatures, which will affect the thermal properties of the materials. (2) Large-tonnage machine press forming requires large production investment, high cost and long cycle...

AI Technical Summary

Problems solved by technology

(2) Large-tonnage machine press forming requires large production investment, high cost and long cycle

(3) Due to the use of machine pressing, it is impossible to make components with complex structures

(4) Some silicon nitride and silicon carbide materials are directly added to the raw materials. Since silicon carbide and silicon nitride are compounds with extremely strong covalent bonds, they can still maintain high bonding at very high temperatures. Strength, which determines the heat treatment process of materials that add silicon nitride and silicon carbide has high temperature requirements, and the improvement of performance is limited

(5) Some silicon nitride and silicon carbide materials are made by adding metal silicon powder to the raw materials, and the material components are reacted to form silicon carbide at high temperature in high-purity nitrogen. However, due to the machine press forming process, the residual silicon in the product The content is high, and the development of nitride crystals is not complete, resulting in the adverse effect of molten silicon on the strength of the material under high temperature service conditions

The above shortcomings make silicon carbide-based refractory materials unable to be used in parts with complex shapes and demanding performance in high-temperature industries