Properties of chrome corundum and its application in refractory materials

 

1. Properties of chrome corundum

The main components of chromium corundum are Al2O3 and Cr2O3, which form a continuous solid solution. According to the Al2O3-Cr2O3 binary phase diagram, adding Cr2O3 to the Al2O3 single-phase material not only does not reduce the refractoriness of the material, but the refractoriness increases with the content of Cr2O3 increase and rise.

When Cr2O3 is added to corundum material, as the temperature increases, Al2O3 and Cr2O3 gradually form a solid solution, so that the corundum particles and the matrix are closely combined, and a ring-shaped solid solution zone is further formed on the surface of the corundum particles, so that the particles and particles of the material can be formed at high temperature. In between, the particles and the fine powder are closely combined, and the combined phase is an aluminum-chromium solid solution phase with a high melting point, and the bond strength is maintained even at high temperatures, so the chromium corundum refractory materials have strong normal temperature mechanical properties and high temperature mechanical properties.

Cr2O3 is a high-quality component of refractory materials, which can form high-melting compounds with various oxides. For example, Cr2O3 and Al2O3 can form a continuous solid solution, the melting point of this solid solution is above 2050 °C; Cr2O3 and MgO/FeO form a high melting point magnesia-chromium spinel/ferrochrome spinel; Cr2O3 and Cu2O can form a melting point above 1600 °C The compound; the melting temperature of the eutectic formed by Cr2O3 and SiO2 reaches 1720 ℃; etc.

In addition, Cr2O3 can also increase the viscosity of the slag, and the increase in the viscosity of the slag can slow down the infiltration rate of the slag into the refractory material. In conclusion, Cr2O3 can improve the slag corrosion resistance and spalling performance of refractories.

2. Application of chrome corundum in refractory materials

Due to its unique excellent properties, chrome corundum is widely used in high temperature fields with harsh environments, including non-ferrous metallurgical furnaces, glass melting furnaces, carbon black reactors, waste incinerators, etc. At the beginning of the development of chromium corundum, it was more widely used, and it was also involved in the field of cement and iron and steel metallurgy. However, due to the strengthening of people's awareness of environmental protection, the voice of chromium-free high-temperature industry is getting higher and higher, and many fields have developed alternative products. However, in some parts where the service environment is relatively harsh, there is still a figure of chrome corundum.

Due to its unique properties, chromium-containing refractories are used in non-ferrous metallurgy industrial kilns with good results. Although many scholars are now studying the chromium-free refractories for non-ferrous metallurgy, so far, chromium-containing refractories have been used in non-ferrous metallurgy. As a smelting furnace lining is still the mainstream. For example, the refractory materials for ausmelt copper smelting furnace not only have to withstand the erosion of the melt (SiO2/FeO series slag, copper liquid, copper matte) and gas phase erosion, but also overcome the temperature caused by the regular replacement of the spray gun. Fluctuations, harsh service environment, at this stage, except for chromium-containing refractories, there is no better material to replace. In addition, the same situation is also faced in zinc volatilization kiln, copper converter, coal gasification furnace and carbon black reaction furnace.

The corrosion resistance of aluminum-chromium-based refractories is better than that of conventional corundum-based or aluminum-silicon-based refractories. Therefore, aluminum-chromium-based refractories are often used as lining materials in key areas such as the severely eroded regenerator furnace, target wall, and molten pool.

Aluminum-chromium-based refractory materials are also commonly used in carbon black reactors, including: combustion section, throat section, reaction section, etc. Aluminum-chromium-based refractory materials are used in the ultra-high temperature (1900 ℃) area of carbon black reactor, chemical attack area of reducing gas (C, CO, H2) and ash, and frequent temperature fluctuation area. Therefore, it is required that the aluminum-chromium-based refractories for carbon black reaction furnaces should have the following characteristics:

1) High refractoriness, high softening temperature under load and low creep rate at high temperature;
2) Stability under strong reducing atmosphere;
3) Strong resistance to molten ash corrosion;
4) Higher high temperature strength and erosion resistance;

5) Good thermal shock stability.

Wanhao is a manufacturer who is specialized in designing various kinds of furnace and making refractory products for electric furnace, ladle, tundish, blast furnace, AOD furnace, IF furnace, etc.

Article Source:Properties of chrome corundum and its application in refractory materials

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