What is the raw material of magnesia carbon brick?

The raw materials for making magnesia-carbon bricks are high-quality sintered magnesia, fused magnesia, graphite, binders and antioxidants. old magnesia brick

The periclase particles in magnesia act as aggregates in refractory bricks. To produce high-quality magnesia-carbon bricks, high-purity magnesia should be selected (MgO content as high as possible, /SiO2≥2, bulk density ≥3.34g/cm3, good crystal development, and magnesia itself porosity ≤3).

Graphite is also the main raw material of magnesia-carbon bricks. Its fixed carbon content, ash composition, oxidation resistance, particle size, shape, volatile matter, and moisture directly affect the performance and use of magnesia-carbon bricks. The high-purity scaly or flake graphite bricks with high carbon content (C≥95-96) are selected to obtain the corrosion resistance, peeling resistance, high temperature strength, and oxidation resistance of magnesia-carbon bricks.

The binder used in magnesia-carbon bricks is very important, and its quality greatly affects the production and quality of refractory bricks.

There are many kinds of substances that can be used as binders for magnesia-carbon bricks, such as coal tar, coal tar and petroleum asphalt, carbon resin, polyol, asphalt denatured phenolic resin, synthetic resin, etc. Due to the high residual carbon rate of phenolic resin, it has good affinity with magnesia and graphite, it is easy to combine magnesia and graphite, and it is easy to spread in magnesia and graphite at room temperature. Resin is still a better binder for the production of magnesia-carbon bricks.

Since the magnesia carbon brick uses high-purity graphite, the amount of liquid phase generated in the brick is small, and oxygen easily penetrates into the brick to oxidize and decarbonize the graphite, and the oxidation resistance of the brick deteriorates. For this reason, metals A1, Si, A1-Si, Antioxidants such as Al-Mg alloy, SiC, etc. They can preferentially react with oxygen to form carbides or oxides, and undergo volume expansion, block or fill pores to densify the bricks, thereby improving the oxygen resistance ratio of refractory bricks.