Fused chromium corundum bricks and sintered chromium corundum bricks belong to chromium corundum products, but the colors of the products produced by the two are different due to the difference in production technology and the difference in the ratio of raw materials.
The main mineral composition of fused chromium corundum brick is α-Al2O3-Cr2O3 solid solution. The secondary mineral composition is a small amount of composite spinel (or no composite spinel), refractory bricks with a chromium oxide content of 1% to 30%.
There are two types of chromium corundum products (fused chromium corundum bricks), cast chromium corundum bricks and sintered chromium corundum bricks.
In general, chromium corundum brick refers to sintered chromium corundum brick. Using α-Al2O3 as raw material, adding appropriate amount of chromium oxide powder and chromium corundum clinker fine powder, after forming, sintering at high temperature. The chromium oxide content of sintered chromium rigid bricks is generally lower than that of fused-cast chromium corundum bricks. It can also be prepared by the slurry casting method. The α-Al2O3 powder and the chromium oxide powder are uniformly mixed, and the glue and organic binder are added to make a thick slurry. At the same time, part of the chromium corundum clinker is added, and the brick is made by the grouting method. After firing, the product has the characteristics of wear resistance, heat shock resistance, acid and alkali corrosion resistance.
The non-shrinkage casting method is used to produce fused chromium-zirconium corundum bricks (abbreviated as AZCS bricks, and the French brand is ER2161). The surface and interior of the fused brick are dark green. The fused brick contains 4.5% shrinkage cavity and no connected pores.
Due to the formation of aluminum chromium spinel solid solution Al2O3·Cr2O3 (about 56%, the rest are oblique zircon phase and glass phase), the viscosity of the glass phase is increased, and the glass corrosion resistance is greatly improved, which is 3.4 times that of ERl681 , Is 2.6 times of ERl711. But Cr2O3 will color the glass liquid and cannot be used for colorless and transparent glass. At the same time, its foaming index is not ideal, so it is an ideal material for the upper structure of the tank kiln.
AZCS fused bricks containing Cr2O3 can be used to build the wall of the colored glass melting furnace to improve corrosion resistance. This type of brick contains about 20% Cr2O3. The main crystal phase is still (C+Z) eutectic, but the corundum base crystal is (Al2-xCrx)O3, and the primary crystal phase of corundum is also (Al2-xCrx)O3. The number of glass phases is similar to that of ordinary fused AZS bricks, which is about 20%. The chemical composition of the glass phase was measured with the aid of micro-area analysis. It was found that a considerable amount of Cr2O3 was dissolved in it, and the chromium ion that formed the glass structure was determined to be Cr2+. That is, cr3+ is reduced to Cr2+ in the melt. This is due to the fact that the melt is in a relatively reducing atmosphere (more than one zodiac is found).
Uses: At present, the application of fused chromium corundum bricks has a wider range of applications, mainly used in carbon black furnaces, slides of steel rolling furnaces, and steel tapping platforms. It has excellent thermal vibration stability and high temperature creep performance, and at the same time meets the requirements of circular economy.
Sintered chromium corundum bricks are widely used in glass kiln lining, brushed glass flow hole cover tiles, glass fiber kiln body and upper air inlet, severely corroded parts of colored glass kiln, and side wall of heat insulation glass fiber kiln , Pool bottom and forehearth, hot metal pretreatment device, coal water slurry pressurized gasification furnace backing, ceramic glaze kiln discharge port, metallurgical melting pool and rotary kiln, zinc oxide melting furnace, garbage incinerator.