What is the raw material of magnesia carbon brick?

The raw materials for producing MgO-C brick are high-quality sintered magnesia, fused magnesia, graphite, binder and antioxidant.

Periclase particles in magnesia act as aggregate in refractory brick. In order to produce high quality magnesia carbon brick, high purity magnesia should be selected (MgO content should be as high as possible, / SiO2 ≥ 2, bulk density ≥ 3.34g/cm3, crystal development well, porosity of magnesia itself ≤ 3%).

Graphite is also the main raw material of MgO-C brick. Its fixed carbon content, ash composition, oxidation resistance, particle size, shape, volatile matter and moisture directly affect the performance and application effect of MgO-C brick. High purity flake or flake graphite brick with high carbon content (C ≥ 95-96%) is selected to obtain the corrosion resistance, spalling resistance, high temperature strength and oxidation resistance of magnesia carbon brick.

The binder used in magnesia carbon brick is very important, its quality will affect the production and quality of refractory brick to a great extent.

There are many kinds of materials, such as coal tar, coal pitch and petroleum pitch, carbon resin, polyol, pitch modified phenolic resin, synthetic resin and so on. Phenolic resin is still a good binder for producing magnesia carbon brick because of its high residual carbon rate, good affinity with magnesia and graphite, easy to combine magnesia and graphite, and easy to spread in magnesia and graphite at room temperature.

Due to the use of high-purity graphite in MgO-C brick, the amount of liquid phase generated in the brick is less, oxygen is easy to penetrate into the brick, which makes the graphite oxidized and decarbonized, and the oxidation resistance of the brick becomes poor. Therefore, metal A1, Si, A1 Si, Al Mg alloy, SiC and other antioxidants are added. They can react with oxygen preferentially to form carbonized matter or oxide, and cause volume expansion, plug or fill air hole to densify the brick, so as to improve the oxygen resistance ratio of refractory brick.