The nature of combination determines high temperature structural strength of Magnesia Brick

Magnesia brick is widely used in steelmaking furnace lining, ferroalloy furnace, mixed iron furnace, non-ferrous metallurgical industry furnace, building material lime kiln, glass industry regenerative room lattice body because of high temperature performance and strong anti-alkali slag ability. Heat exchanger, refractory industry, high-temperature calcining kiln and tunnel kiln. The refractoriness of magnesia brick is as high as above 2000 ℃, and the softening temperature of the load varies with the melting point of the combined phase and the liquid phase produced at high temperature. General magnesia brick load softening start temperature in the 1520 ~ 1600 ℃, while the high-purity magnesium boast a heavy softening temperature of up to 1800 ℃.
Magnesia  brick at 1000 ~ 1600 ℃ under the linear expansion rate is 1.0% to 2.0%, and approximate or linear, refractory products, the thermal conductivity of magnesium specializes in second only to carbon brick, with the temperature rise reduce. Under the condition of water cooling at 1100 ℃, the number of thermal shock of magnesia brick is only 1 ~ 2 times. MgO brick on the CaO and ferrite alkaline slag resistance, but with SiO2 and other acidic slag resistance is weak, and therefore can not be used in direct contact with the silica bricks, generally separated by a neutral brick. At room temperature, the conductivity of magnesia brick is very low, but at high temperature, its conductivity will not be ignored. The performance of magnesium brick, due to the use of raw materials, production equipment, process measures, etc. have a greater difference. Magnesia brick load softening temperature and the collapse of the beginning of the temperature difference is not much difference between this and the silica brick, because the main phase of magnesium bricks is periclase, but the periclase crystals in the magnesia brick is not crystalline network skeleton, but by the binding of the binder.(http://www.magnesiabricks.com/product/magnesia_brick.html)
Therefore, the nature of the combination determines the high-temperature structural strength of magnesia brick. In common magnesia brick, as the combination is generally calcareous olivine and magnesium rose pyroxene and other low-melting silicate phase, although the magnesia brick constitute the higher melting point of the periclase grain, but at about 1500 ℃ melting Of the silicate phase exists, and its liquid phase viscosity at low temperature is very small, therefore, reflects the deformation of ordinary magnesia brick deformation temperature and collapse temperature difference is not large, but with a greater difference in refractoriness. And the softening start temperature of high-purity magnesia brick can reach 1800 ℃, mainly because the combination between the periclase grains is forsterite or dicalcium silicate, and the melting temperature of eutectic with MgO is high , The lattice strength between the crystal and plastic deformation at high temperature is small, crystal particles with good.