The fused zirconia corundum brick (AZS) are mostly used in the parts with the highest temperature in the tank furnace and the parts with the most serious erosion by liquid glass. Generally, different brick types are marked by the amount of ZrO₂. Bricks are mainly composed of α- It is composed of two crystalline phases and glass phase of corundum and plagioclase zircon. Plagioclase zircon α- In addition to corundum eutectic, the rest are free. The more ZrO₂ in the brick, the more free plagioclase zircon. The corrosion resistance of these two crystalline phases is very good. Moreover, the two crystal phases are closely combined and the structure is uniform and dense. Therefore, the corrosion resistance is stronger.

Due to the introduction of a small amount of Na₂O into the brick, the crystallization area of mullite is reduced. Mullite crystal phase is difficult to precipitate, and glass phase is formed to fill between the above crystal phases. This kind of glass phase is eroded by high-temperature glass liquid, and then produces albite glass with high viscosity. Because a certain amount of ZrO₂ is dissolved, the viscosity is higher. This layer of high viscosity vitreous remains on the brick surface and is not easy to spread, thus protecting the brick. If the crystal of the brick is coarse, it is not easy to form a high-viscosity layer after erosion. Then the glass liquid is easy to penetrate into the brick and corrode the brick quickly.

The alteration process of fused zirconia corundum brick

The alteration process of fused zirconia corundum brick is that the molten glass brick reacts with the original glass phase in the brick and gradually diffuses and dissolves. After that α- Corundum and monoclinic zircon are slowly dissolved in turn. The viscosity of liquid glass near the brick surface increases, forming a protective layer against erosion. At the same time, the metasomatic reaction will produce α- Corundum, nepheline, skeleton plagioclase zircon, etc.

Generally, the glass liquid in the metamorphic layer of the bricks near the liquid level at the upper part of the pool wall has obviously penetrated into the bricks. However, the eutectic of corundum and plagioclase zircon is still associated with the residual glass.

The surface of the brick at the lower part of the pool wall is α- Remains of corundum and plagioclase zircon and turbid glass phase. The reaction of glass phase and liquid glass in brick will produce nepheline liquid phase. This dissolved part of zircon. Thus forming a high viscosity metamorphic layer. When the temperature decreases, the dissolved ZrO₂ will precipitate star or dendritic crystals. This is the secondary crystallization of plagioclase zircon.

In the high viscosity layer at the lower part of the pool wall, the secondary crystallization of plagioclase zircon coexists with nepheline crystallization. With the extension of service time, these two crystalline phases may be taken away by the glass liquid flow. Then it further diffuses to the glass liquid. The clinozoite, which is difficult to melt, may be partially dissolved and remain in the glass liquid as a stone in the finished product.