Erosion Mechanism Of Large Ladle Slag Lining Brick

The MgO-C brick is a basic composite refractory materials which has good thermal shock resistance and slag resistance.It is widely used as lining of the steelmaking converter, wall of the electric furnace, and slag line of the ladle, and has a good effect.Application situation and analyzing of physical and chemical properties of different kinds of MgO-C bricks provided by different enterprises were described and the results indicate that except A60, other types of the MgO-C brick have no obvious difference in using life and erosion rate, so the A60 brick has a worst comprehensive performance.At the same time, electron probe analyzing and SEM were used to analyze microstructure of the MgO-C brick produced by different enterprises. The results showed that the carbon of the MgO-C brick was oxidated first and formed a decarbonized zone,then the aluminum,calcium,silicon and other elements in the slag filtered into the brick along the decarbonized zone, combined with the magnesia grain in the brick and formed the low-melting point materials, so made the brick become flexible. Under the repeat wash of the steel and thermal stress changing, the magnesia grain departed away from the brick, so it cause the erosion of the brick. The research results also proved that if the content of the Al2O3 is too high in the slag, it will form many spinels in the contact place between the brick and the slag. At the same time spinels formation will cause the volume expanding and bring on the brick destroy. However, a small amount of spinels will be beneficial to protect the brick from destroyed. After microstructure observation the results shows that A60 and C60 have a higher erosion rate, and A120 and B60 bricks have good using effect.To verify the result, some slag resistance experiments have been done, the result coincided with the microstructure analyzing. So,the A60,C60 brick has a worst erosion,and the A120,B60 brick has a better using effect.