Chrome corundum refractories generally refer to the main components of refractory products materials as alumina and chromium oxide (<40%). In addition, it also contains a small amount of impurities. It has the characteristics of high refractoriness, high hardness, excellent corrosion resistance, good thermal shock resistance and high wear resistance. Chromium corundum refractories are widely used in the lining of coal-water slurry pressurized gasifiers, ladle refining furnaces and carbon black reactors. And Lining of slag gasification furnace and glass melting furnaces in the petrochemical industry. Rongsheng Refractory Manufacturer, Chrome corundum bricks can also be used as chromium corundum platform bricks for heating furnaces. They are an indispensable material in high-temperature industries. Chrome Corundum Bricks.

Introduction of Chrome Corundum Bricks

The fused corundum and sintered corundum in the use of chrome corundum bricks are called chromium corundum bricks. Alumina-chrome bricks use aluminum chromium, chromium oxide and alumina as the main raw materials. The shaped refractory brick products with alumina and chromium oxide content of not less than 90%, and chromium oxide content of not more than 50% obtained by high-temperature firing are called chrome corundum bricks.

AL2O3 and Cr2O3 belong to the corundum-type structure, the radius of Cr3+ is 0.620Å, and the radius of AL3+ is 0.535Å. According to the empirical formula:

Because the difference between Cr3+ and AL3+ ion radius is less than 15%. Cr ions can continuously and infinitely replace AL in the AL2O3 lattice, forming an infinitely continuous replacement solid solution.

The crystal structure of Cr2O3 and AL2O3 are the same, and the ionic radius differs by 13.7%. Therefore, Cr2O3 and AL2O3 can form infinite solid solutions at high temperatures. From the “liquid-solid” phase line, as the content of Cr2O3 increases, the temperature at which the liquid phase begins to appear increases. Therefore, adding an appropriate amount of Cr2O3 to AL2O3 can significantly improve the mechanical properties and high-temperature performance of corundum refractories.

Cr2O3 can form a high melting point compound or a eutectic with a higher melting temperature with many common oxides. For example, FeO·Cr2O3 spinel produced by Cr2O3 and FeO has a melting point of up to 2100℃. Cr2O3 and AL2O3 can form a continuous solid solution. In addition, Cr2O3 can also greatly increase the viscosity of the slag and reduce the fluidity of the slag, thereby reducing the corrosion of the slag to the refractory. Therefore, adding an appropriate amount of Cr2O3 to the refractory material can significantly reduce the structural spalling of the furnace lining material caused by slag erosion. Chrome Corundum Bricks.

There is no obvious regularity between the corrosion ability of slag to chrome corundum refractories and the basicity of slag. When the slag basicity is 2, the chrome corundum brick has the best resistance to iron slag erosion. When the slag basicity is 0.2, the corrosion depth of copper slag to the chrome corundum bricks are the smallest. When the slag basicity is 0.35, the corrosion depth of tin slag to the chrome corundum brick is the smallest. When the alkalinity of the lead slag is 0.3, the thickness of the residue is the largest and the depth of the reaction layer, erosion layer and penetration layer is the smallest. When the slag basicity is 0.37, the corrosion resistance of chrome corundum bricks is the best. At 1400℃, the corrosion resistance of chrome corundum bricks against non-ferrous metal slag is nickel slag> lead slag> copper slag> tin slag.

Chrome Corundum Bricks Technical Data

Characteristics and Performance of Chrome Corundum Brick

Under normal circumstances, aluminum content above 90% is called corundum brick. Chrome corundum bricks generally refer to sintered chrome corundum bricks. It is mainly made of α-AL2O3 as raw material, adding appropriate amount of chromium oxide powder and chromium corundum clinker powder, after molding, high temperature firing.

The content of chromium oxide in sintered chrome corundum bricks is generally lower than that of fused cast chrome corundum bricks. It is also possible to use a slurry pouring method to mix α alumina powder and chromium oxide powder uniformly, and add a part of chromium corundum clinker, which is a brick grouting method.

Fused chrome zircona corundum brick, also called AZCS brick, adopts non-shrinkage casting process. Both the skin and the interior of the brick are dark green. The molten brick contains 4.5% shrinkage holes and no connecting pores. The colored glass furnace can use AZCS bricks containing Cr2O3 to build the pool wall, which improves the corrosion resistance of the pool wall.

The main crystal phase of corundum is (al2-xcrx)O3. The glass phasor is similar to ordinary fused AZS bricks. Through micro-area analysis, the chemical composition of the glass phase is determined. A large amount of Cr2O3 is dissolved in the glass, and the chromium ion forming the glass structure is identified as Cr2+. In other words, cr3+ is reduced to Cr2+ in the melt. This is because the melt is in a relatively reducing atmosphere. Chrome Corundum Bricks.

Application of Chrome Corundum Bricks

At present, chrome corundum bricks have been widely used. Mainly used for carbon black furnaces, steel rolling furnace sliding tables, and steel platforms. It has good thermal stability and high-temperature creep performance.

Sintered chrome corundum bricks are widely used in glass kiln linings and liquid cave cover glass bricks. Glass fiber kiln body and upwind, stained glass kiln and heat insulation glass fiber kiln wall with severe corrosion. Supported by hot metal pretreatment equipment at the bottom and front of the furnace, coal-water slurry pressurized gasification furnace, metallurgical melting pool at the discharge port of ceramic glaze kiln, rotary kiln, and zinc smelting furnace.

The tuyere of the melter gasifier is operated by oxygen, the heat load of the tuyere brick is high, and the working conditions are harsh. It has a strong oxidation effect on carbon-containing refractories. Molten slag and molten iron are formed here, so the tuyere bricks under high temperatures are subject to strong corrosion. The tuyere is made of SiC brick, and the furnace lining of the tuyere, the upper part of the overhaul hole is made of magnesia carbon brick, which has a hydration phenomenon. It is recommended to use Si3N4 combined SiC brick as the lining. The combination of tuyere bricks and SiC bricks combined with p-SiC has a good effect. Through the corrosion test of Al2O3-Cr2O3 bricks, it was found that it has very good corrosion resistance and spalling resistance. Therefore, silicon carbide bricks and chrome corundum bricks should be used for the tuyere and above. Sialon combined with corundum bricks should also be a very good choice.

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