well known,Dispersion type breathable brickIt has high porosity and permeability. In actual production, by adding carbon-containing compounds to the mixture, since the material can be burned at low temperature without residue, the initial porosity can be obtained by burning out the intermediate material at low temperature. Dispersion-type air-permeable bricks are distributed with inter-penetrating pores of different sizes. When the air blowing is stopped during use, the steel and slag in the ladle will penetrate into the deep area of ​​the air-permeable brick through these pores, so the working surface will be damaged. Solid and tight parts. When the ladle is stopped or when the air blowing is restarted, the working surface of the breathable brick is subjected to the periodic penetration and erosion of the molten steel, causing the pores to block, blow through or peel off.
　　
Use performance:
　　
1, Slag resistance
　　
In order to improve the material's slag resistance and resistance to molten steel penetration, Cr2O3 or part of chromium corundum is usually added to the corundum spinel permeable brick. Cr2O3 and a-Al2O3 have the same crystal structure, Cr2O3 not only improves the material's performance The slag resistance increases the wetting angle between the material and the molten steel, and has a significant improvement in the blockage of the pores of the breathable brick due to the penetration of the molten steel.
　　
The aluminum-chromium solid solution and the independent chromium-containing glass phase formed by Cr2O3 fine powder and Al2O3 at high temperature are used to form a liquid phase with a certain viscosity when it contacts with the slag in the molten steel smelting process, thereby hindering the molten steel slag. At the same time, it can absorb iron oxide and magnesium oxide in the slag, and form a dense spinel in the working layer of the breathable brick, which improves the slag resistance of the breathable brick.
　　
However, when Cr2O3 is added to the material, after high temperature firing or use, Cr3 is oxidized to Cr6, and Cr6 is toxic and will pollute the environment. Therefore, in order to save energy and protect the environment, Cr2O3 should be avoided as much as possible, and by replacing raw materials, the The high temperature performance after adding Cr2O3 reaches the level of adding Cr2O3.
　　
2, thermal shock resistance
　　
The main damage method of the breathable brick is thermal shock damage. With the continuous increase of the tapping temperature, there is a large temperature difference between the working surface of the breathable brick and the intermittent, which requires the material to have extremely high thermal shock resistance. The introduction of spinel phase into the castable will improve the thermal shock resistance of the breathable brick.
　　

The oxide or non-oxide added to the breathable brick forms a solid solution phase with the aggregate at high temperature, which increases the high temperature strength of the brick, improves the permeability of the brick, and resists the erosion of the slag in the ladle to the breathable brick. After the brick is heat treated at high temperature, its performance is improved to meet its use requirements.