According to the different components of refractory bricks, they can be divided into five categories, namely: silicon aluminum series refractory bricks, alkaline series refractory bricks, carbon containing refractory bricks, zirconium containing refractory bricks, and insulation refractory bricks. Any furnace is not built with just one type of refractory brick, it requires a combination of different refractory bricks to be used.

Refractory bricks are important furnace building materials in industries such as metallurgy, cement, ceramics, and glass. The quality of refractory bricks not only affects the lifespan of kiln equipment, but also has a significant impact on the quality of these industrial products. Although many refractory brick manufacturers have made significant technological progress in producing refractory brick technology and raw material preparation, there are still some refractory brick manufacturers whose product quality is not good enough, and measures should be taken to quickly improve.

The quality of refractory bricks can be evaluated based on main indicators such as fire resistance, load softening temperature, room temperature compressive strength, residual linear shrinkage, and porosity. There are many factors that affect these indicators, and a brief explanation will be provided below.

1. Fire resistance: Fire resistance is the property of refractory bricks that can resist high temperatures without melting during use, and is one of the important indicators for evaluating quality. If the fire resistance is not high, due to prolonged exposure to high temperature during use, a large amount of liquid phase will be generated inside the brick, causing all masonry to be destroyed due to melting. The level of fire resistance depends on the chemical mineral composition of the raw material, the particle composition of the raw material, and the viscosity of the liquid phase.

2. Load softening temperature: The load softening temperature is related to the structural strength of the kiln at high temperatures, generally expressed as the temperature at which a certain amount of deformation is caused by the static load of 2 kilograms per square centimeter of refractory bricks. Bricks with less glass phase, network structure formed by crystallization, and low porosity have higher softening temperature under load.

3. Room temperature compressive strength: It represents the structural strength of refractory bricks and their ability to bear static loads. It is closely related to the impact and friction resistance of bricks. The compressive strength depends on factors such as the density, raw material composition, and sintering degree of the product.

4: Porosity: Porosity is closely related to slag erosion resistance. The resistance to slag erosion mainly depends on the chemical properties of refractory materials (acidic, alkaline, neutral). Clay bricks belong to acidic refractory materials, and increasing the AL2O3 content can increase the corrosion resistance to acidic and alkaline slag. Materials with the same chemical properties, due to their high porosity, will increase the contact area between the brick material and the slag, allowing the slag to penetrate into the interior of the brick through the pores, reducing its resistance to slag erosion. The size of porosity depends on factors such as particle composition, bulk density, and sintering degree of the same product of the granular material.

5: Residual linear shrinkage: The volume fixation of refractory materials at high temperatures during residual linear shrinkage. During the use of bricks, due to long-term heating, they are further sintered, resulting in volume shrinkage and causing furnace body cracking, stitching and deformation. To reduce residual shrinkage, the product should be fired at sufficient temperature.

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