Introduction of Raw Materials for Magnesia Carbon Brick
Introduction of raw materials for magnesia carbon brick
The main raw materials of magnesia carbon bricks include fused magnesia or sintered magnesia, flaky graphite, organic binders and antioxidants.
Introduction of raw materials:
Magnesia is the main raw material used in the production of magnesia carbon bricks, which are divided into fused magnesia and sintered magnesia. Compared with sintered magnesia, fused magnesia has the advantages of coarse magnesia crystal grains and large bulk density.
2. Carbon source
Whether it is in traditional magnesia carbon bricks or low-carbon magnesia carbon bricks that are currently in large use, scaly graphite is mainly used as its carbon source. This is mainly due to its excellent physical properties: non-wetting to slag, high thermal conductivity, and low thermal expansion. In addition, graphite and refractory materials do not co-melt at high temperatures and have high refractoriness.
3. Bonding agent
(1) Asphalt materials. Tar pitch is a kind of thermoplastic material, which has the characteristics of high affinity with graphite and magnesia, high residual carbon ratio after carbonization, and low cost. Due to the enhancement of environmental awareness, the use of tar pitch is now decreasing.
(2) Resin materials. Synthetic resin is prepared by reacting phenol and formaldehyde. It can be well mixed with refractory particles at normal temperature. The residual carbon ratio after carbonization is high, but it forms a glassy network structure after carbonization and resists thermal shock to refractory materials. Sexual and antioxidant properties are not ideal.
(3) A substance obtained by modification on the basis of asphalt and resin. If the binder is carbonized to form a mosaic structure and carbon fiber material is formed in situ, the binder will improve the high temperature performance of the refractory.
In order to improve the oxidation resistance of magnesia carbon bricks, a small amount of additives are often added. Common additives are Si, Al, Mg, Al-Si, Al-Mg, Al-Mg-Ca, Si-Mg-Ca, SiC, B4C, BN and recently added additives such as Al-BC and Al-SiC-C.