What are the reasons for the damage of the ladle breathable brick

In the process of using ladle breathable bricks by steel manufacturers, the main reasons for the damage of breathable bricks are thermal stress, mechanical stress, mechanical abrasion, and chemical corrosion. The breathable brick consists of a breathable core and a breathable seat brick. When the bottom blowing gas is open, the working surface of the breathable core will be in direct contact with the high temperature molten steel. The bottom blowing gas is a cold flow, which constitutes a very high temperature difference with the high temperature molten steel. As the number of times of use increases, the ventilating brick core is corroded deeper due to the rapid heat and cold, and it is prone to cracks.

The working surface of the bottom air-permeable brick is in direct contact with the high-temperature molten steel, and the temperature of the non-working surface is relatively low. During the recycling process of steel joining, pouring, and hot repair, the volume of the air-permeable brick and adjacent refractory materials is caused by temperature changes. The volume change, due to the existence of the temperature gradient and the difference in thermal expansion coefficient between the metamorphic layer and the original layer, the degree of volume change from the working surface of the ventilating brick to the non-working surface is abrupt, which will cause shearing of the ventilating brick. The shear force causes the ventilating brick to have cracks in the horizontal direction, and under severe conditions, it will cause the ventilating brick to crack horizontally.

During the tapping process, the molten steel will have a high-strength scouring of the bottom of the ladle, which will accelerate the erosion of the air-permeable brick. When the upper surface of the air-permeable brick is higher than the bottom of the bag, it will be sheared and washed away by the activity of molten steel. The part higher than the bottom of the bag will generally be washed away after one use. In addition, after the essence is finished, if the valve is quickly closed, the reverse impact of molten steel will also accelerate the corrosion of the breathable brick.

The working surface of the air-permeable brick core is in contact with steel slag and molten steel for a long time. The steel slag and molten steel contain iron oxide, ferrous oxide, manganese oxide, magnesium oxide, silicon oxide, etc., while the components of the air-permeable brick include alumina, silicon oxide, etc. , It will react to generate low-melting material and be washed away.

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