At present, the working lining of the ladle, especially the slag line, is mostly made of carbon-containing refractory materials.
Before use, new ladles must be pre-baked. The order is low, medium, and high fire. The temperature is around 1000℃. Baking can take 20-30 hours, 3-5 days, or longer.
Many ladles skip anti-oxidation measures during baking. This causes a 20mm oxidized decarburized layer on magnesium carbon bricks. Few ladles use coatings, but their effect is poor. The coatings are also inconvenient, so most sites abandon them.
During the baking process of the newly built ladle, when the temperature exceeds 800℃, the graphite and resin in the magnesia carbon bricks oxidize rapidly, and the oxidation rate gradually slows down as the thickness of the oxide layer increases.
The entire baking process will cause the magnesia carbon brick to produce a complete decarburization layer of at least 20mm. The longer the baking time, the deeper the oxidation decarburization layer. The decarburization layer has almost no bonding strength, large porosity, and loose structure. After being filled with molten steel, the decarburization layer will fall off quickly under the scouring of molten steel and slag, resulting in waste of lining materials.
Generally, the thickness of the newly built working lining of the ladle is about 200mm. After the ladle is offline, the remaining working lining is about 60mm. After deducting the 20mm of oxidation, the effective consumption thickness of the working lining is about 120mm. The thickness of the oxidized part accounts for about 15% of the effective consumption part. By applying the anti-oxidation coating, the effective consumption thickness of the magnesia carbon brick can be increased by about 20mm, which is equivalent to increasing the service life of the lining by about 15%.
The role of new anti-oxidation coatings
The new anti-oxidation coating has a good anti-oxidation effect on the resin and graphite in the magnesia carbon brick at a temperature of 1100℃ and below, making its loose layer and decarburization layer almost zero.
In field use, it can effectively prevent the oxidation of magnesia carbon bricks during ladle baking, increase the effective consumption of magnesia carbon bricks, and improve service life.
It can effectively reduce the consumption of ton steel of ladle refractory materials, which is of great significance to resource conservation.
This new anti-oxidation coating can be used for anti-oxidation during baking of other carbon-containing ladle working linings.
