What are the differences between zirconium corundum bricks and chrome corundum bricks?

The following introduces the difference between zirconium corundum brick and chrome corundum brick:

1. Zirconium corundum brick

Zirconium corundum brick is a refractory brick made of industrial alumina and zircon sand. According to the manufacturing process, zirconium corundum bricks can be divided into two types: fused zirconium corundum bricks and fired zirconium corundum bricks.



Fused zirconium corundum brick Fused zirconium corundum brick is commonly known as white iron brick, also known as corundum-degrada zircon brick. The main chemical composition is Al2O3 50% to 70%, ZrO2 20% to 40%, and the rest is SiO2. The main mineral composition is baddeleyite zircon (ZrO2), corundum (α-Al2O3) and glass phase. The baddeleyite crystal forms the backbone of the brick body, ZrO2 has a high melting point (2715°C), good chemical stability, and strong corrosion resistance to acidic and alkaline media, especially glass liquid.

Fused zirconium corundum bricks are used in industrial furnaces such as glass melting furnaces. The parts used in glass melting furnaces are to build the upper pool wall, small furnace flat, small furnace stack, tongue and breast wall, etc. Fused zirconium corundum bricks should pay attention to the following problems in use:

①Irregular changes in thermal expansion. The expansion curve of fused zirconium corundum brick has an abnormality around 1000 ℃, and its internal ZrO2 crystal undergoes reversible crystal transformation, and there is a large volume change. Therefore, bricks containing ZrO2 should not be used at temperatures around 1000 ℃. Sharply fluctuating parts. When baking the kiln, the temperature change should not be too large at 900 ~ 1150 °C, generally not more than 15 °C/h, and a stable temperature rise is required. In order to prevent cold wind from blowing in some parts, other bricks should be used to prevent them from bursting.

②Shrinkage. When pouring and molding, shrinkage cavities often appear at the casting mouth. There are many pores in the brick body and the density is poor. Therefore, when building the glass melting pool wall, the shrinkage cavities are all directed towards the inside of the kiln. If the sprue is facing outwards, when the brick body is eroded to a very thin thickness, it will cause a leakage accident of the molten glass. When used in the upper flame space of the pool kiln, the service life is very long, and the problem of running glass liquid will not occur. Therefore, the casting mouth is used outwards to prolong the service life.

③ Eutectic. Fused zirconium corundum bricks and clay bricks are in contact with masonry, and eutectic phenomenon will occur at a high temperature of 1300 ° C. Therefore, when selecting refractory materials, it is necessary to avoid contacting masonry with two refractory materials with serious eutectic phenomenon, such as silica bricks in The underside of the fused zirconium corundum brick is most susceptible to erosion by the fused zirconium corundum brick.

(2) Sintered zirconium corundum brick

Sintered zirconium corundum bricks are also called ceramic bonded aluminosilicate zirconium bricks. Compared with fused zirconium corundum bricks, the chemical composition of sintered zirconium corundum bricks is similar. However, it has the advantages of no carbon, low glass phase content, uniform structure, no shrinkage crater, good thermal shock stability and corrosion resistance.

2. Chrome corundum brick.

Chrome corundum bricks are corundum refractory bricks containing Cr2O3. Since Cr2O3 and Al2O3 form a continuous solid solution, the high temperature performance of chrome corundum bricks is better than that of pure corundum bricks. Chrome corundum brick has good high temperature resistance and slag corrosion resistance, and its slag resistance increases with the increase of Cr2O3 content.

Chromecorundum brickis mainly used as the lining material of the lower part of the petrochemical industry slag gasification furnace, and the part of the glass melting furnace that is not afraid of glass coloring, which is severely eroded, and can also be used as the sliding nozzle material.

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