Common refractory bricks can be classified according to material, chemical properties or application scenarios. The following are the main types and their characteristics:
Classification by material and chemical properties
Silicon-aluminum refractory bricks
● Clay bricks: refractory clay is the main material, alumina (Al₂O₃) content is 30%~48%, refractory temperature is 1200~1500℃, suitable for blast furnaces, hot blast furnaces, etc.
● High-alumina bricks: Al₂O₃ content ≥48%, refractory temperature 1650~1790℃, good thermal shock resistance, used in high temperature environments such as metallurgy and cement rotary kilns.
● Silica bricks: SiO₂ content ≥93%, refractory temperature above 1650℃, acidic refractory materials, used in coke ovens and glass melting furnaces.
● Mullite bricks: moderate Al₂O₃/SiO₂ ratio, high refractoriness, excellent thermal shock resistance, mostly used in glass kilns.
Basic refractory bricks
● Magnesia bricks: MgO content ≥ 80%, refractoriness ≥ 2000℃, resistant to alkaline slag erosion, used in converters and electric furnaces.
● Magnesia-chrome bricks: Containing MgO and Cr₂O₃, resistant to high temperatures and strong slag resistance, but gradually replaced because of the toxic chromium content.
● Dolomite bricks: mainly CaO and MgO, used for alkaline converter linings.
Neutral refractory bricks
● Silicon carbide bricks: high SiC content, refractoriness over 2000℃, good thermal conductivity, wear resistance, used for blast furnace bottoms and steel ladles.
● Corundum bricks: Al₂O₃≥90%, refractoriness ≥2000℃, high high temperature strength, suitable for key parts of glass kilns.
● Carbon bricks: mainly carbonaceous materials, resistant to high temperatures and resistant to alkaline slag erosion, used for blast furnace refractory materials.
Refractory bricks containing special ingredients
● Zirconia-containing bricks: such as zircon bricks and AZS bricks, which have high refractoriness and are resistant to glass liquid erosion, and are used in glass tank kilns.
● Talc bricks: The refractory temperature is about 1400℃, and they are used for the thermal insulation layer of high-temperature furnaces.
● Silicate bricks: Made of kaolin, the refractory temperature is about 1450℃, and they are suitable for the building materials industry.
2. Classification by function and use
Lightweight insulating refractory bricks
● Such as lightweight clay bricks and mullite insulation bricks, they have high porosity, low thermal conductivity, and a refractory temperature of about 1100℃, and are used for the thermal insulation layer of the furnace.
Wear-resistant and corrosion-resistant bricks
● Such as aluminum-carbon bricks and silicon nitride combined with silicon carbide bricks, which have both wear resistance and corrosion resistance, and are suitable for metallurgical furnace linings.
Thermal shock-resistant bricks
● Such as anti-stripping high-alumina bricks, which improve thermal shock stability by adding ZrO₂, are used for equipment with frequent temperature fluctuations.
3. Examples of typical application scenarios
● Steel industry: high alumina bricks and magnesia bricks are used in converters; silicon carbide bricks are used in steel ladles.
● Glass industry: silica bricks and zircon bricks are used in melting furnaces.
● Cement industry: silica bricks and high alumina bricks are used in rotary kilns.
● Chemical industry: carbon bricks and magnesia carbon bricks are used in reactors.