Report on the influence of substances such as chromium oxide and alumina on the performance of magnesium chromium bricks

The RH furnace has functions such as natural decarburization, fine adjustment of composition, temperature rise of molten steel, forced decarburization by oxygen blowing, and desulfurization by powder injection. It has become an essential external refining equipment for smelting high-end steel grades such as electrical steel, pipeline steel, ship steel, galvanized steel, tinplate, etc. During the operation of RH furnace, the furnace is in a negative pressure state, and the steel and argon are in a fountain like state, circulating at high speed in a closed pipeline composed of an ascending insertion tube, a lower groove, and a descending insertion tube. At the same time, a large amount of alloy or desulfurizer is added to adjust the composition of the steel, which has strict requirements for the vacuum stability, high-temperature performance, erosion resistance, and slag resistance of refractory materials; The RH furnace belongs to the metallurgical equipment with intermittent operation, and the insertion tube and lower groove are frequently subjected to alternating hot and cold thermal shocks throughout the furnace service. Therefore, refractory materials are required to have good thermal shock resistance. Magnesium chromium materials have advantages such as high fire resistance, high high-temperature strength, strong resistance to alkaline slag corrosion, and excellent thermal stability. They also have certain adaptability to acidic slag and are widely used in key parts such as cement kiln firing zone, steel refining RH furnace lower groove, circulation pipe, and various copper smelting furnace linings. Below is an introduction to its service environment and damage situation, and an outlook on its application prospects in high-temperature new equipment.

In the production process of magnesium chromium bricks, there are various additives present, such as chromium oxide, alumina, zirconia, etc. These additives have a very important impact on the performance of magnesium chromium bricks, as shown below:

1. The Effect of Chromium Oxide on Magnesium Chromium Refractory Materials

Chromium oxide is one of the main components of magnesium chromium refractory materials. The appropriate addition of high-purity and small particle size chromium oxide components in magnesium chromium refractory materials has the following three main effects on magnesium chromium refractory materials:

(1) Increase direct binding rate

When the Cr₂O₃ content in periclase increases, the dihedral angle between silicate melt and periclase increases, which also leads to poorer wettability between silicate and magnesium chromium spinel compared to silicate and magnesium iron spinel; This phenomenon also leads to the distribution of silicates only in the form of isolated islands between magnesium chromium spinels, and the direct binding in magnesium chromium bricks also increases.