News

News

Follow us to learn about news and information

What is the particularity of the forming method of zirconium corundum brick

Release time:

2021-11-12 10:57

The molding method in which the material is directly cast into products after melting at high temperature is called melt-casting molding method. Because of the common use of electric arc furnace melting materials, so the casting molding products are also known as electric melting products. Common electrofusion products are fused mullite brick, fused zirconium corundum brick, fused corundum brick and so on.

The biggest feature of melt casting is to pour the high temperature melt directly into the model. This requires the model to have high fire resistance, good air permeability, high impact strength and thermal shock resistance, and does not react with the melt. Commonly used models are made of quartz sand, corundum sand or graphite plates. Fused and cast refractory bricks have the characteristics of large grain size, compact structure, high mechanical strength and good corrosion resistance. Fused mullite bricks and fused zirconium corundum bricks are mainly used in the glass industry.

The common quality problems of cast refractory bricks are: component segregation in the cooling process after casting and cracking caused by local thermal stress. To solve these problems mainly through the production process control to achieve. For example, the composition segregation is controlled by adjusting the cooling solidification rate, and the cracking problem of the product is solved by annealing process, controlling the hardening and cooling rate of the casting during annealing. There are two ways of annealing, namely natural annealing and controllable annealing. Natural annealing is to put the casting together with the model into the incubator and let it cool slowly naturally; while controlled annealing is to put the casting into the annealing kiln after demolding for slow cooling according to the annealing curve.

Shrinkage is also one of the common quality problems of cast refractory bricks. The shrinkage cavity is generally concentrated below the upper surface of the article, which reduces the density of the article and the uniformity of the structure. In order to reduce or eliminate the shrinkage cavity, the dense casting method, the quasi-shrinkage-free casting method and the shrinkage-free casting method are used in the process.

Application of fused corundum brick in float glass melting furnace

The glass melting furnace is a thermal equipment for melting glass composed of refractory materials. The service efficiency and service life of glass melting furnace depend on the variety and quality of refractory materials to a great extent. The development of glass production technology depends to a large extent on the improvement of refractory manufacturing technology. Therefore, the rational selection and use of refractory materials is a very important content in the design of glass melting furnaces. To do this, we must master the following two points, one is the characteristics and applicable parts of the selected refractory materials, and the other is the use conditions and erosion mechanism of each part of the glass furnace.

Process Improvement of Electro-fused Zirconium Corundum Pavement Brick

Electrically fused zirconium corundum brick is made of industrial alumina powder and zircon sand (containing 66% of zirconium oxide and 34% of silicon dioxide) melted at high temperature in an electric furnace. After melting, it is cast into a shape (the casting temperature is 1780-1840 ℃), injected into the model and cooled to form a solid close to white. Its petrographic structure consists of the eutectoid body and glass phase of corundum and zirconium clinite, it is a eutectoid body of corundum phase and zirconium clinoptilite phase, and the glass phase is filled between their crystals.

How to overcome the defects produced in the casting and annealing of fused zirconium corundum bricks

Electrofused zircon corundum brick in the production will produce a variety of defects, resulting in the use of poor quality products. The physical and chemical inhomogeneity of zirconium corundum bricks is often the main reason for the defects of the products. Particles that are not melted through in the batch and gas inclusions that have not been discharged from the melt in time are all physical inhomogeneities. The difference in the composition of the melt along the depth of the furnace is a chemical inhomogeneity.

Causes of Serious Erosion of Zirconium Corundum Brick in Glass Electric Melting Furnace

The erosion of fused zirconium corundum brick is mainly divided into physical action and chemical action. Physical action refers to the glass melting furnace wall in the long-term operation process, repeatedly subjected to the impact of rapid cooling and rapid heat, the surface must undergo a contraction of the expansion of the change process. Due to excessive fatigue, the structure of fused zirconium corundum brick is damaged, resulting in increased surface cracks and loose structure. Therefore, under the action of air flow, material and glass liquid washing, cracking and peeling, and this process will be repeated.