Magnesia carbon brick raw materials

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

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

Graphite is also the main raw material of magnesia carbon bricks. Its fixed carbon content, ash composition, oxidation resistance, particle size, shape, volatile content, moisture, etc. all directly affect the performance and use effect of magnesia carbon bricks. It is best to use high-purity flake or flake graphite bricks with high carbon content (C≥95-96%) to ensure the corrosion resistance, spalling resistance, high temperature strength, and oxidation resistance of magnesia carbon bricks.

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

There are many types of materials that can be used as binders for magnesia-carbon bricks, such as coal tar, coal tar and petroleum pitch, special carbon resins, polyols, pitch-denatured phenolic resins, and synthetic resins. Due to the high carbon residue rate of phenolic thick. A purpose, 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. So far, phenolic Resin is still a better binder for the production of magnesia carbon bricks.

Since magnesia carbon bricks use high-purity graphite, the amount of liquid phase generated in the bricks is small, and oxygen can easily penetrate into the bricks to oxidize and decarburize the graphite. The oxidation resistance of the bricks becomes worse. For this reason, metals A1, Si, A1-Si must be added. , Al-Mg alloy, SiC and other antioxidants. They can preferentially react with oxygen to form carbon compounds or oxides, and expand in volume, block or fill pores to densify the bricks, thereby improving the anti-oxygen performance of the refractory bricks.