Corundum bricks refer to refractory materials with an alumina content greater than 90% and corundum as the main crystalline phase. The following is a description of their main properties:
Refractory Performance:
Corundum bricks have very high refractoriness, generally exceeding 1790℃, and a load softening start temperature greater than 1700℃. Adding Cr₂O₃ to high-purity corundum materials can further improve refractoriness; chromium corundum bricks have superior refractoriness and load softening temperature compared to high-purity corundum products.
Strength:
The room temperature compressive strength of high-purity corundum bricks is generally 70MPa-100MPa, while the room temperature compressive strength of high-performance chromium corundum bricks is generally greater than 150MPa, reaching a maximum of 340MPa. This is because an Al₂O₃-Cr₂O₃ solid solution is formed during the firing process, enhancing the interparticle bonding and improving the material strength.
Chemical Stability:
Corundum bricks exhibit excellent chemical stability, showing strong resistance to acidic or alkaline slags, metals, and molten glass. Cr₂O₃ or Cr₂O₃-containing demonstrate strong resistance to corrosion from steel slag, non-ferrous smelting slag, and coal gasification slag. The high viscosity of the liquid phase formed by the reaction of Cr₂O₃ with slag prevents molten slag from penetrating into the brick body.
Thermal Shock Stability:
The thermal shock stability of corundum bricks is related to their microstructure. Dense products exhibit good corrosion resistance but poor thermal shock stability. When Cr₂O₃ is added to corundum, the thermal shock stability decreases with increasing Cr₂O₃ content (10%-66%). In other words, chromium corundum bricks with low Cr₂O₃ content have better thermal shock stability than those with high Cr₂O₃ content.
Wear resistance:
Corundum bricks have high hardness and excellent wear resistance, making them suitable for high-temperature and severe wear conditions, such as in the steel and non-ferrous smelting industries. It has significantly better wear resistance than other types of bricks and can withstand mechanical wear and airflow erosion at high temperatures.