The Core : A Comprehensive Guide to High-Alumina Bricks

The core differences of high-alumina bricks lie in their composition, especially the content of alumina (Al₂O₃), which directly determines their “performance capabilities”. According to national standards, they are divided into three basic grades:

1. Grade 1 High-Alumina Bricks: The “King” in High-Temperature Fields

• Composition: Alumina content ≥ 75%, equivalent to a “pure-blood warrior” among high-alumina bricks. The corundum phase accounts for more than 60%, with minimal impurities.
• Advantages: Refractoriness reaches over 1790℃, like a shield capable of withstanding volcanic lava. When under long-term pressure at 1400℃, its deformation rate is 40% lower than that of ordinary bricks, making it suitable for bearing high loads.
• Application Scenarios: The “cora area” of blast furnaces in iron and steel plants (upper-middle part of the furnace body) and regenerators of glass kilns. These places have temperatures exceeding 1200℃ and are filled with corrosive gases, and only Grade 1 bricks can withstand such conditions for a long time.

2. Grade 2 High-Alumina Bricks: The King of Cost-Effectiveness

• Composition: Alumina content ranges from 60% to 75%. Corundum and mullite form a “dual-sword combination” structure, providing both hardness and toughness.
• Advantages: Refractoriness is between 1750℃ and 1790℃. Although slightly inferior to Grade 1 bricks, it has more outstanding thermal shock resistance—it remains intact after 15 cycles of water cooling at 1100℃, making it particularly suitable for environments with frequent temperature changes.
• Application Scenarios: The transition zone of cement rotary kilns (subjected to material friction and alternating high temperatures of 1300℃ daily) and gasifiers in chemical plants. It offers high cost-effectiveness and a long service life.

3. Grade 3 High-Alumina Bricks: The Backbone of Basic Protection

• Composition: Alumina content ranges from 48% to 60%, with a relatively high glass phase content, more like an “economical and practical armor”.
• Advantages: Refractoriness is between 1710℃ and 1750℃. Although not top-tier, it excels in low price and easy processability, and can be made into various special-shaped bricks.
• Application Scenarios: The backing layer of industrial kilns (not in direct contact with high temperatures but requiring structural support) and furnace linings for temporary maintenance. It meets basic protection needs at low cost.