1. The refractoriness of magnesia brick is as high as 2000℃, and the softening temperature under load does not change greatly with the melting point of the binding phase and the liquid phase produced at high temperature. Generally, the starting temperature of load softening of magnesia bricks is 1520～1600℃, while the starting temperature of high-purity magnesia bricks can reach 1800℃.
2. In ordinary magnesia bricks, low-melting silicate phases such as forsterite and magnesia pyroxene are generally used as the combination. Although the periclase crystal grains that constitute the magnesia brick have a higher melting point, they may be at 1500°C. The left and right molten silicate phase exists, and the viscosity of its liquid phase is very small at high temperature. Therefore, it reflects that the load deformation temperature and collapse temperature of ordinary magnesia bricks are not much different, but there is a big difference from the refractoriness. The load-softening start temperature of high-purity magnesia bricks can reach 1800°C, mainly because the combination of periclase grains is forsterite or dicalcium silicate, and the melting temperature of the eutectic formed by it and MgO is high. , The lattice strength between the crystals is large and the plastic deformation at high temperature is small, and the crystal particles are well combined.
3. The linear expansion rate of magnesia brick at 1000～1600℃ is generally 1.0%～2.0%, and it is approximately or linear. In refractory products, the thermal conductivity of magnesia brick is second only to carbon-containing bricks. It increases with temperature. High and low. Under the condition of 1100℃ water cooling, the number of thermal shocks of magnesia bricks is only 1 to 2 times. Magnesium bricks have strong resistance to alkaline slags containing CaO and ferrite, but weak to acidic slags containing SiO2.
4. Therefore, it should not be in direct contact with silica bricks when in use, and should generally be separated by neutral bricks. At room temperature, the conductivity of magnesia bricks is very low, but at high temperatures, its conductivity cannot be ignored. The performance of magnesia bricks varies greatly due to the different raw materials, production equipment, and technological measures used.
5. Magnesia bricks are widely used in steelmaking furnace linings, ferroalloy furnaces, iron mixers, non-ferrous metallurgical furnaces, lime kilns for building materials, and regenerator grids in the glass industry due to their good high-temperature performance and strong resistance to alkaline slag. Heat exchangers, high-temperature calcining kilns and tunnel kilns in the refractory industry.
