The main chemical components of the magnesium-calcium refractory are MgO and CaO, and the main phases are cristobalite and Calcite, which brings together the advantages of MgO and CaO.
Compared with magnesium-chromium refractory materials, the magnesium-calcium refractory materials used for AOD furnace lining are:
(1) The raw material resources are rich, the price is low, and it does not contain chromium, so it will not increase the chromium inclusion in the molten steel. It is very important to control not only the chromium-free steel liquid but also the chromium content of the chromium-containing steel liquid.
(2) The main components MgO and CaO have high melting points (2800 Centigrade and 2570 Centigrade, respectively), low vapor pressure and stable thermodynamic properties.
(3) The MgO-CaO combination has a larger two-sided angle than the MgO-MgO combination, which is beneficial to improve the resistance to slag permeability and resistance to slag corrosion. The thermal shock resistance of magnesium- calcium-based materials is better than that of magnesium-chromium-based materials.
(4) Magnesium-calcium-based materials are very resistant to oxidation and reduction, even in AOD furnaces and at high temperatures.
(5) Magnesium-calcium-based materials exhibit obvious creep properties at temperatures as low as 1260 Centigrade. This shows that this kind of material has strong resistance to spalling on the hot surface, so it can become a dense material with the largest corrosion resistance when used.
(6) The magnesium-calcium refractory contains highly reactive f-CaO (free calcium oxide can repair the cracks of this type of material and form a very dense impervious working surface, so it has a very high Corrosion resistance.
(7) The presence of f-CaO can purify molten steel, and is especially suitable for smelting pure steel. In recent years, with the rapid development of steelmaking technology, as one of the important refractory materials for the iron and steel industry, magnesium-calcium-based refractory materials have been used in steelmaking, continuous casting tundish, refining furnaces, especially in smelting special steel and pure steel It is far superior to other refractory materials.