Performance and use of magnesia brick

The refractoriness of the magnesia brick is as high as 2000 ° C or higher, and the load softening temperature does not vary greatly depending on the melting point of the binder phase and the liquid phase produced at a high temperature. Generally, the load-softening start temperature of magnesia bricks is between 1520 and 1600 ° C, while the high-purity magnesia bricks have a softening start te·mperature of up to 1800 ° C.

 

In ordinary magnesia bricks, as a combination, it is generally a low-melting silicate phase such as calcium forsterite and magnesia, although the calcite crystals constituting the magnesia have a higher melting point, but melt at about 1500 ° C. The silicate phase exists, and its liquid phase has a small viscosity at high temperature. Therefore, it reflects that the load temperature of the ordinary magnesia brick is not much different from the collapse temperature, but it is quite different from the refractoriness. The loading softening start temperature of high-purity magnesia bricks can reach 1800 °C, mainly because the combination of the magnesite grains is forsterite or dicalcium silicate, and the melting temperature of the eutectic formed by the MgO is high. The lattice strength between the crystals is large and the plastic deformation at high temperatures is small, and the crystal particles are well bonded.

 

The linear expansion rate of magnesia bricks at 1000-1600 °C is generally 1.0%-2.0%, and is similar or linear. In refractory products, the thermal conductivity of magnesia bricks is second only to carbon-containing bricks, which increases with temperature. reduce. Under the condition of water cooling at 1100 °C, the thermal shock frequency of the magnesia brick is only 1 or 2 times. Magnesia bricks have strong resistance to CaO and ferric alkaline slag, but have weak resistance to acidic slags such as SiO2.

Therefore, it cannot be directly contacted with silica bricks during use, and is generally separated by neutral bricks. At normal temperature, the conductivity of magnesia bricks is very low, but at high temperatures, its conductivity cannot be ignored. The performance of magnesia bricks is greatly different due to the different raw materials, production equipment and process measures.

 

The magnesium brick of Zhengzhou sunrise refractory material is widely used in steelmaking lining, iron alloy furnace, mixed iron furnace, nonferrous metallurgical industrial furnace, building material lime kiln and glass industry due to its high temperature performance and strong resistance to alkaline slag. Heat exchangers for regenerator grids, high temperature calcining kiln for refractory industry, tunnel kiln, etc.