Magnesia Refractories Used In Induction Furnaces

According to the type of metal melting and smelting purposes, induction furnace lining can be built with acidic, neutral and basic refractories. The basic refractories are mainly composed of magnesia, lime, BeO, spinel and magnesium dolomite. Basic refractories are mainly used in small induction furnaces for smelting steel and alloy. 

Since the magnesia sand has large expansion coefficient and poor thermal shock resistance, it is not suitable to large and intermittent induction furnaces. 

 

In order to improve the performance of magnesia materials, an appropriate amount of Al2O3 and Cr2O3 are added. Wherein, Al2O3 powder is added to generate spinel at high temperature and can suppress the generation of cracks. Cr2O3 powder can form complex spinel (Mg, Fe) O · (Cr, fe) 2O3 with Fe in the slags at a high temperature and promote the densification of the material. Chrome spinel has superior erosion resistance to acidic and basic slags and low thermal expansion, so it improves the corrosion resistance and thermal stability properties of the material. 0.5-1.5% of boric acid is added into magnesia refractory linings as a binding agent. 

 

When used magnesia spinel is added into magnesia ramming mass, with the increasing of Al2O3, the expansion coefficient and stability of the materials are improved.