The Nature of Conjugate Determines the High Temperature Structural Strength of the Magnesia Brick

Because of the good high temperature performance and strong alkali slag resistance of the magnesia brick, it is widely used in steelmaking furnace lining, ferroalloy furnace, metal mixer, nonferrous metallurgical industry furnace, lime kiln building material, glass industry regenerator heat exchanger grid Lattice, high temperature calcined kiln and tunnel kiln refractory industry. The fire resistance of the magnesia brick is above 2000 ℃, the fire resistance under load is equal to the melting point of the combined phase, and the liquid phase result is changed at high temperature. Generally, the softening temperature of load of magnesia brick is 1520 ~ 1600 ℃.
Magnesia brick at  the 1000 ~ 1600 ℃ linear expansion rate is generally 1.0% to 2.0%, in refractory products, the thermal conductivity of magnesia brick after carbon brick, with the temperature decreases. In the 1100 ℃ water cooling conditions, the number of magnesia brick thermal shock is only 1 to 2 times. MgO brick has a strong basic slag resistance to CaO and ferrite, but the weak acid slag has strong resistance to SiO2, so it is not used in direct contact with silica brick, and is generally separated by neutral brick. At room temperature, the magnesia brick is very low in conductivity, but at high temperatures, the conductivity is not negligible. The performance of magnesia brick, due to different raw materials, production equipment, technical measures, there is a big difference. The difference between the starting temperature and the collapse temperature of the magnesia brick is not so big as that of the silica bricks because the main phase composition of magnesia bricks is periclase and the periclase crystals are not the crystalline network skeleton , But by combination gluing.(http://www.magnesiabricks.com/product/magnesia_brick.html)
Therefore, the combination of the nature of the magnesium brick determines the high-temperature structural strength. In ordinary magnesium bricks, although the magnesite grains of magnesium olive bricks have a higher melting point, there is a molten silicate phase of about 1500 ° C, and the viscosity of liquid phase viscosity at high temperature is very small, so the load deformation temperature And the collapse temperature is not big, but with the difference of stainless steel is bigger. The starting temperature of the high-purity magnesia-magnesia bricks can reach 1800 ℃, mainly because the periclase is a combination of forsterite or dicalcium silicate, the melting temperature of the eutectic solution is high, the formation of MgO is high, and the intensity between the lattices is large , Plastic deformation at high temperature is small, a good combination of crystalline particles.