Ultra-low cement or non-cement in-situ silicon carbide whisker self-bonding silicon carbide prefabricated part

Abstract

The invention discloses an ultra-low cement or non-cement in-situ silicon carbide whisker self-bonding silicon carbide prefabricated part used for a cooling wall of a blast furnace and a reaction sagger tank for reduction iron-making and a preparation method. The silicon carbide prefabricated part comprises the following components in part: 70 to 80 parts of silicon carbide, 9 to 18 parts of silicon metal powder, 0 to 5 parts of carbon powder, 0 to 6 parts of silicon dioxide micro powder, 0 to 2.5 parts of pure calcium aluminate cement and 0 to 6 parts of hydraulic alumina which are used as the raw materials, and dispersant, water or silica sol. The silicon carbide prefabricated part is formed by a vibrating pouring method and is subjected to carbon embedding high-temperature thermal treatment in a resistance furnace after being maintained and dried. The product has high hot strength, strong erosion resistance and good thermal shock resistance. Meanwhile, the product with a complex shape can be produced. Moreover, the product has a simple and easily controlled process and low production energy consumption.

Description

technical field [0001] The invention relates to a silicon carbide prefabricated part used for blast furnace staves and reaction sagger tanks for reducing ironmaking, in particular to an ultra-low cement or cement-free in-situ silicon carbide whisker self-bonded silicon carbide prefabricated part and its preparation method . Background technique [0002] The main material of the blast furnace stave is copper, and the thermal conductivity of copper is 401 W / m.k. However, due to high temperature softening, copper cannot be in direct contact with molten iron. Therefore, a transition zone of non-metallic refractory material needs to be added between molten iron and copper to play a role. The purpose is to protect the copper stave and cooperate with the copper stave to reduce the temperature of the molten iron and make the molten iron hang slag smoothly. The reaction tank for reducing ironmaking is a reaction vessel for scrap steel, scrap iron and reducing agent carbon at high te...

AI Technical Summary

Problems solved by technology

These materials have the following disadvantages: (1) low thermal conductivity

(2) Poor thermal shock resistance

(3) Machine pressing is used to make components with complex structures

(4) Large-tonnage machine press forming requires large production investment

(5) Conventional castables use cement as a binder, which affects the high temperature performance of the material

(6) High production energy consumption

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 their own high bonding strength at very high temperatures. It is difficult to combine with other particles, which determines that the heat treatment temperature of the material combined with silicon nitride and silicon carbide is high, and nitrogen protection treatment is required at the same time, so the production energy consumption is high

(7) The production process is difficult to control

Some silicon nitride and silicon carbide materials are made by adding metal silicon powder to the raw materials, and reacting the material components to form nitrides at high temperature in high-purity nitrogen. However, since nitrogen is one of the reaction phases, the temperature of the nitriding reaction is just above silicon Its melting point is around 1410°C, so that the nitriding temperature, nitriding time, nitrogen flow rate and nitrogen pressure are strictly controlled. A slight deviation will change the final phase composition and microscopic appearance, resulting in performance differences.