Do you know the difference between magnesia carbon brick, magnesia alumina carbon brick, and alumina magnesia carbon brick
1, Differences in Composition and Structure
1) Magnesia carbon brick (MgO-C brick)
Main components: Magnesium oxide (MgO, content 60% -90%) and graphite (C, content 10% -30%), with a small amount of metal antioxidants (such as Al, Si) added.
Features: High temperature resistance (up to 1700 ℃) and slag erosion resistance, but graphite is prone to oxidation and requires moisture-proof storage.
2) Magnesium aluminum carbon brick (MgO-Al ₂ O ∝ - C brick)
Composition: Adding aluminum oxide (Al ₂ O3, content 5% -15%) on the basis of magnesia carbon brick to form a magnesia alumina spinel structure.
Features: Significant improvement in thermal shock stability (up to 20 times of thermal shock resistance), suitable for environments with large temperature fluctuations, such as ladle slag lines.
3) Aluminum magnesium carbon brick (Al ₂ O ∝ - MgO-C brick)
Composition: Mainly composed of alumina (Al ₂ O ∝ ≥ 60%), supplemented by MgO (10% -30%) and graphite (5% -15%).
Characteristics: It has stronger resistance to molten steel erosion (slag erosion rate is 30% -50% lower than magnesia carbon brick), but its high-temperature strength is slightly lower, and it is mostly used for ladle and electric furnace cover.
2, Performance comparison and application scenarios
Slag resistance and applicable environment
1) Magnesia carbon brick: suitable for high alkalinity slag environments (such as converter lining), as MgO reacts with CaO in the slag to form high melting point phases.
2) Magnesium aluminum carbon brick: suitable for neutral or weakly acidic slag (such as refining furnaces), spinel structure can inhibit slag infiltration.
3) Aluminum magnesium carbon brick: designed for high FeO slag (such as electric furnaces), Al ₂ O Ⅲ reacts with FeO to form a dense layer that blocks erosion.
Mechanical strength and lifespan
Magnesia carbon bricks have high strength at room temperature (≥ 30MPa), but may peel off due to graphite oxidation at high temperatures;
The addition of Al ₂ O3 in magnesia alumina carbon bricks makes the high-temperature strength more stable (≥ 25MPa);
Aluminum magnesium carbon brick has a longer lifespan (20% -40% higher than magnesium carbon brick), but it is necessary to avoid using it at ultra-high temperatures (>1600 ℃).
3, Selection suggestions and industry trends
Select based on operating conditions
Converter and electric furnace walls: priority given to magnesia carbon bricks;
Ladle slag line: Recommended magnesium aluminum carbon brick;
Iron pre-treatment equipment: Aluminum magnesium carbon bricks are more economical.
