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Characteristics of industrial magnesia carbon brick

2021-12-08 13:57:20

Requirements of manufacturers of magnesia carbon brick for binder

1. It has high viscosity and fluidity at room temperature, and has good wettability to magnesia and graphite

2. The binder can be further condensed during heat treatment to make the products have high strength

3. During heat treatment, the binder will not cause excessive expansion and contraction of the product, so as to avoid cracking of the product

4. The content of C should be high, and the carbon polymer after coking treatment has good high-temperature strength

Generally, coal tar, coal tar, special carbon resin, polyol, pitch modified phenolic resin, synthetic phenolic resin, etc. are used for the production of magnesia carbon bricks.

Slag erosion resistance analysis. The SEM morphology of the crucible of MgO-C brick eroded by LF slag with less and more iron shows that a thin slag layer is formed on the surface of MgO-C brick after being eroded by LF slag, and the slag layer of the sample with less iron is relatively obvious. Due to the short erosion time, after being eroded by two kinds of slag, the erosion layer on the surface of MgO-C brick is relatively thin. At the same time, the flake graphite on the surface of MgO-C brick in contact with slag is oxidized and the matrix is relatively loose. Moreover, the erosion of low iron LF slag on magnesia carbon brick is significantly stronger than that of high iron LF slag, and the erosion layer is relatively deep. This is because the wetting angle of low iron slag on MgO-C brick is relatively small, and the wetting rate of MgO-C brick is fast under the same conditions, which accelerates the melting corrosion of MgO-C brick.

Calcium magnesium brick

Industrial magnesia carbon brick

The researchers further found that the LF slag first wetted the surface of the magnesia carbon brick, then invaded the matrix of the magnesia carbon brick along the pores left after graphite oxidation, filled around the magnesia particles, chemically eroded and melted with the magnesia particles, and formed a low melting point liquid phase containing Ca, Si and Al, thus eroding the magnesia particles step by step. It can be inferred that with the extension of reaction time, the cemented structure will be formed in the magnesia carbon brick, the magnesia particles will be embedded in the liquid phase, and the edges and corners of the magnesia particles will be melted by the slag and become smooth, so that the composition and performance, especially the coefficient of thermal expansion, of the erosion layer of the magnesia carbon brick and the original brick layer are very different. When it is subjected to thermal shock and thermal shock during use, the working face of magnesia carbon brick will be peeled off and damaged. Under the condition of LF refining outside the furnace, due to the high refining temperature, the viscosity of slag decreases, and the internal temperature of furnace lining is also high, the slag can penetrate deeper into the interior of refractory materials to form a thicker reaction layer, which will aggravate the melting loss of magnesia carbon brick lining and cause serious peeling off and damage. Therefore, the effect of LF slag on MgO-C brick is mainly manifested in chemical corrosion and poor thermal shock stability, spalling and damage.


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