The Role of Aluminum in Magnesia Carbon Brick
The main effect of adding aluminum powder into magnesia carbon brick is antioxidant. The presence of carbon in magnesia carbon brick is to prevent slag erosion in the brick, and carbon itself has the characteristics of easy oxidation. When carbon in magnesia carbon brick is oxidized, the erosion resistance of brick is declined sharply, which will accelerate the damage of the brick, reduce its service life. In order to prevent the oxidation of carbon, we add metal aluminium powder to protect the carbon in brick. The reaction mechanism is as follows:
1. when magnesia carbon brick is heated, active metal aluminum in brick will firstly react with carbon, became high melting point carbide, then carbon will reunite, getting Al4C3 and Al2O3. Al4C3 will stay on the surface of MgO, to prevent the penetration of slag erosion. In this way, it will improve the bricks erosion resistance, slag resistance and spalling resistance.
2. When the magnesia carbon bricks under high temperature condition, active aluminum will be oxidized and become high melting product Al2O3. It is a phase change process from metal into nonmetal, the volume of oxidation Al2O3 will have a expansion, making the pores in brick be dense, increasing bricks bulk density and forming the ceramic combination, so as to improve the bricks high temperature rupture resistance.