Due to good high temperature performance of magnesia brick, strong alkaline slag resistance, is widely used in steel industry of the steelmaking furnace lining, the ferroalloy furnace, metal mixer, non-ferrous metallurgy industry furnace, building materials of lime kiln, glass industry regenerator grid body of heat exchanger, refractory industry of high temperature calcination kiln and tunnel kiln, etc. The refractoriness of magnesia brick reaches up to above 2000 ℃, and refractoriness under load is with the melting point of combination phase and generates liquid phase under high temperatures result happening changes. General magnesia brick's load softening temperature is at 1520 ~ 1600 ℃.
Magnesia brick's linear expansion rate at 1000 ~ 1600 ℃ is generally 1.0% ~ 2.0%, in refractory products, the thermal conductivity of magnesia brick is next only to carbon brick, it reduces with the rise of temperature. Under the condition of 1100 ℃ water-cooled, the number of magnesia brick's thermal shock is only 1 ~ 2 times. Magnesia brick has strong basic slag resistance capability to CaO and iron oxygen, but weak acid slag resistance ability to SiO2, so when using, is not direct contact with silica brick, and generally will be separated with a neutral brick. Under normal temperature, the conductivity of the magnesia brick is very low, but at high temperature, the conductivity will not be ignored. Performances of magnesia brick, because of the different raw materials, production equipment, technology measures, have a large difference. The differences between the rul starting temperature of magnesia brick and collapse temperature is not big, it has bigger difference with silica brick, it is because the main phase composition of magnesia brick is periclase, but periclase crystal is not crystalline network skeleton within magnesia brick, but was cemented by combination.
Therefore, the nature of the combination decides high temperature structure strength of magnesia brick. In ordinary magnesia brick, although periclase grain melting point of magnesia brick is higher, but there are around 1500 ℃ molten silicate phase existing, and the viscosity of liquid phase viscosity under high temperature is very small, so the differences between the load deformation temperature of common magnesia brick and collapse temperature is not big, but has bigger difference with refractoriness. And high purity magnesia brick's rul start temperature can reach 1800 ℃, mainly due to the combination of the periclase grain is forsterite or dicalcium silicate, and eutectic solution's melting temperature it and MgO formed is high, the strength between crystal lattice is big and plastic deformation under high temperature is small, crystal particles combination is good.