As a basic refractory material, magnesia calcia refractory material has the remarkable characteristics of high refractoriness and strong resistance to basic slag. It is an important high-grade refractory material.
The main chemical components of magnesia calcia refractories are MgO and CaO, and the main phases are periclase and calcium, which bring together the advantages of MgO and CaO.
High temperature resistance of magnesia calcia refractory materials
The melting point of MgO is 2 825 ℃, and the melting point of CaO is 2 623 ℃, both of which are high melting point oxides. The high temperature vapor pressure of CaO is lower than that of MgO, and its thermodynamic properties are more stable.
Slag resistance of magnesia calcia refractories
CaO reacts with slag to generate high-melting-point mineral phases C2S and C3S, which increase the viscosity of the slag and the wetting angle, thereby inhibiting the erosion and penetration of the slag on the refractory and having good slag resistance.
Thermal shock resistance of magnesia calcia refractories
CaO has good high-temperature plasticity and good creep properties, so magnesia calcia refractories have good thermal shock stability and better impact resistance than magnesia chrome bricks.
High temperature vacuum stability of magnesia calcia refractory materials
Out-of-furnace refining is mostly carried out under high temperature vacuum, so the stability of refractory materials must be considered. Research results show that high-purity magnesia dolomite bricks are very stable under high temperature vacuum, very low weight loss rate, which is obviously superior to magnesia chrome bricks.
The role of magnesia calcia refractory materials in purifying molten steel
The free CaO in magnesia calcia refractory materials easily reacts with non-metallic impurities such as Al2O3, SiO2, S, and P in molten steel, causing them to transfer to the slag. Therefore, magnesia calcia refractory materials have the function of purifying molten steel. Magnesia calcia refractory materials are preferred materials for smelting clean steel and special steel. Theoretical and experimental results show that magnesia calcia refractory materials with high CaO content (>50%) have better purification effects on molten steel.
In recent years, with the rapid development of steelmaking technology, magnesia calcia refractory materials, as one of the important refractory materials, are used in steelmaking, continuous casting tundishes, and refining furnaces. Especially in the smelting of special steels and pure steels, they are far superior to other refractory materials.
