Renovation of Fused Zirconia Corundum Bricks in Glass Kiln
2024-10-10
Zhengzhou Sunrise Refractory Co., Ltd.
News
This article analyzes in detail the specific applications of several refractory bricks and their anti-corrosion properties, especially the advantages and alteration process of AZS bricks in high temperature environments.
Fused zirconium corundum (AZS) bricks are mostly used in areas with higher temperatures in the kiln and areas that are severely corroded by molten glass. Different brick models are usually marked by the content of ZroZ. The brick is mainly composed of two crystal phases: α-corundum, polystone and glass phase. Baddeleyite and α-corundum are eutectics, and the rest are free phases. The corrosion resistance of these two crystal phases is parallel, and the two crystals are closely combined, with a uniform and dense structure, so the corrosion resistance is stronger.
Since the amount of NaZ attracted in the brick is very small, the mullite crystallization zone becomes narrower, and the mullite crystal phase is difficult to precipitate, while the glass phase is filled between the crystal phases. After this glass phase is corroded by high-temperature glass liquid, a layer of dense sodium feldspar glass will be generated. Since a certain amount of ZrO2 is dissolved in it, it has a higher viscosity. This layer of high-viscosity glass remains on the surface of the brick and is not easy to diffuse, thus protecting the brick body. If the crystal of the brick is coarse, it is not easy to generate a high-viscosity layer after being corroded, and the glass liquid can easily penetrate into the interior of the brick and quickly corrode the brick body.
The alteration process of zircon-corundum bricks is that the molten glass bricks interact with the glass phase in the bricks, gradually diffuse and dissolve, and then the α-corundum and monoclinic zircon in the bricks slowly dissolve in turn. The viscosity of the glass liquid near the surface of the brick increases, forming a layer of anti-corrosion protective layer. At the same time, the replacement reaction produces corundum, nepheline, skeletal zircon, etc.
Generally, the glass liquid in the brick metamorphic layer near the liquid surface on the upper part of the pool wall has obviously penetrated into the brick body, but the corundum and baddeleyite eutectic are still connected by the residual glass phase. The bricks at the lower part of the pool wall have corundum, baddeleyite and turbid glass phases. Due to the reaction between the glass phase in the brick and the glass liquid, the nepheline liquid phase is generated, which dissolves part of the photolyzed stone and forms a high-anvil metamorphic layer. When the temperature is lowered, the dissolved ZrOZ will precipitate star-shaped or dendrite crystals, which is secondary crystallization.
In the high privacy layer at the bottom of the pool wall, secondary crystals of retained stone coexist with nepheline crystals. As the use time increases, these two crystal phases may be carried away by the glass liquid flow and then further diffuse into the glass liquid. The stones that are more difficult to melt may be partially dissolved and remain in the glass liquid in the form of finished stones.
