The direct bonding magnesia chrome brick is made of high-purity sintered magnesia and chrome concentrate with SiO2 < 2% as raw materials through high-temperature sintering. The direct bonding degree of the product increases with the reduction of SiO2 content and the increase of sintering temperature. The formation of direct bonding is a process of dissolution precipitation. Increasing the content of fine powder of chromium concentrate is conducive to the formation of direct bonding. In the presence of silicate, the bonding between periclase and periclase will be strengthened by Cr2O3, but reduced by Al2O3 and Fe2O3. The higher the content of Cr2O3, the more intragranular and intergranular spinels, the higher the strength of the product and the stronger the slag resistance
The directly bonded magnesia chrome bricks are generally divided into different grades of Cr2O3% ≥ 12% and Cr2O3 ≥ 20%, with low porosity, high strength, strong wear resistance, good corrosion resistance and good spalling resistance. The products are widely used in electric arc furnaces, copper smelting furnaces, and external refining furnaces
