Chromite Sand AFS40-45 and Chromite Powder 200# Powder for Magnesium Chromium Castables
Magnesium-based castables have good slag resistance and corrosion resistance to molten steel. It is usually used in key parts such as slag lines of high-grade steel ladles. However, magnesium sand itself has a thermal expansion coefficient of up to, poor thermal shock resistance, and low anti-stripping ability. Chromite sand AFS40-45 and chromite powder 200 # fine powders are usually added as auxiliary materials in magnesium chromium castables to improve the thermal shock resistance and service life of magnesium-based refractory materials.
The role of chromite sand and chromite powder is mainly reflected in the following aspects:
1. Adding an appropriate amount of South Africa chromite ore sand AFS40-45 grain and 200F powder to chromium-based castables is beneficial for improving the bonding ability of magnesite crystal components. Meanwhile, it reduces the apparent porosity of refractory materials and improves their bending strength. At the same time, adding chromite sand can cause some small cracks in the castables, which is beneficial for improving the thermal shock resistance of the castables.
2. In the castable with chromite sand added, the crystals of chromite sand and magnesium sand diffuse with each other. At high temperatures, chrome ore sand and magnesium sand react closely, forming a solid solution of magnesite. After cooling, the solid solution decomposes, forming a type of spinel in the middle of the crystal. The formation of this spinel improves the bonding degree of magnesite crystals. As a result, the mechanical properties of magnesium chromium castable can be effectively improved.
3. Chromite sand has good quenching performance and thermal conductivity, which can improve the thermodynamic performance of the castable. So it can resist repeated erosion of molten steel and improve thermal shock resistance.