Properties of 1700 sintered corundum ring refractory bricks

The corundum refractory bricks manufactured by traditional refractory production technology are called sintered corundum refractory bricks. With the development of metallurgy, petrochemical, chemical fertilizer, glass and other industries and industries, the demand for sintered corundum refractory bricks is increasing, and the quality requirements are getting higher and higher. Therefore, it is of great significance to study the properties of sintered corundum refractory bricks.

As we know, refractory products containing more than 90% AL2O3 are corundum refractory materials. Some countries also classify refractory products with AL2O3 content of 82%~90% as corundum refractory products. Some also stipulate the SiO2 content. For example, pure corundum bricks stipulate that the SiO2 content cannot exceed 0.4%; for corundum-mullite-bonded corundum products, the SiO2 content fluctuates within the range of 8% to 9%.

TiO2, Fe2O3, MgO, CaO and R2O are all impurities in corundum refractory brick products, and these impurities mainly come from raw materials. There are also iron oxides brought in when the raw materials are ground. Alumina contains less than 0.01 TiO2, and there are also impurities as additives to promote sintering or aluminum silicate raw materials, so that the TiO2 content reaches 1%~1.5%. Tio2, Fe2O3, and FeO reduce the creep stress of corundum refractory bricks, and make the mineral composition and microstructure of the products very different.

Corundum refractory bricks are mainly composed of a-AL2O3 crystals with different particle sizes and bonding parts. Products produced with sintered corundum clinker have large grains of a-AL2O3 crystals. Products made of fused corundum have fragmented large single crystals. The crystallization of a-AL2O3 of the two types of products depends to a large extent on the purity of raw materials, and the products with additives are mainly clinker and products. Firing temperature. When the alumina raw material is very pure, increasing the firing temperature can make the a-AL2O3 crystal grow into a plate shape. Two types of products, most of which are based on corundum clinker (sintered or fused), corundum crystals become very large, generally 80~150m, occasionally 100~800m.

Classification by chemical composition: All types of corundum refractory brick products with porosity, the chemical purity is related to the density of the product. Ultra-dense and high-density products with the highest density can be produced with low-alkali alumina, while pure corundum can produce compact products. The remaining types of corundum refractory bricks are only compact, dense and general. Corundum-mullite-bonded corundum products mainly depend on chemical composition and phase composition. Although the porosity of the product has a great influence on the slag resistance, it is worse than when using pure corundum refractory bricks. It can also be said that the impact of corundum purity on the slag resistance is greater than that of the porosity. Generally, the porosity of corundum refractory brick products is mostly at 18. %~23%. The closed porosity fluctuates between 3% and 6.6%, and the closed pores are the pores in the corundum crystal particles. It can be considered to increase the density of the product according to the increase degree of closed porosity. Increase the density of the product, and reduce the air permeability, which proves that the size of the pores decreases.

The calcining temperature of the corundum clinker and the firing temperature of the product have a decisive influence on the porosity of the product. Secondly, the particle composition of the mud, the additives and the molding pressure of the brick have an important influence on the porosity of the product. The strength of all corundum refractory bricks is closely related to the pores. The compressive strength of corundum refractory bricks fluctuates in a relatively large range just like the porosity, and the high-density and ultra-dense products have the highest strength. At the same time, corundum refractory bricks have high wear resistance and impact resistance, and can be used as a wear-resistant lining for grinding bodies.