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Magnesium-carbon brick and aluminium-magnesium-carbon brick characteristics

wallpapers Industry 2020-12-30
Carbon composite refractories are high-end refractories developed in the late 1970s and have received great attention from the world's metallurgical industry. It uses the characteristics of high refractoriness of graphite, large thermal conductivity, small expansion coefficient and resistance to infiltration to improve the refractory. The thermal stability, corrosion resistance and high temperature creep resistance of materials have greatly improved the economic benefits of the metallurgical industry.
In the 1970s and 1980s, foreign steel ladles mainly used medium and low-grade aluminum-magnesium-carbon bricks. Since the 1980s, China has also Many series of new refractory materials for ladle has been developed successively, such as magnesium-carbon and aluminum-magnesium-carbon (the distinction between magnesium-aluminum-carbon and aluminum-magnesium-carbon is based on the content of magnesium oxide and aluminum oxide in the material).
Characteristics of magnesia carbon brick and aluminum magnesia carbon brick
Magnesia carbon brick is the earliest carbon composite refractory product. In the ladle, the magnesia carbon brick is mainly used in the position of the slag line, and its aggregate is generally fused 97 (MgO mass fraction ≥ 97%), 98 (MgO mass fraction ≥ 98 %) Ordinary fused magnesia or large crystalline magnesia, the carbon (graphite) mass fraction is generally 10% to 12%, and there is a certain amount of antioxidants. Magnesia carbon bricks perfectly combine the excellent high-temperature performance of magnesia materials and the good resistance of carbon materials to the permeability and thermal shock stability of high-temperature slag. Especially when the emergence of thermosetting phenolic resin binders in the 1970s solved the problem of magnesia, The problem of the compounding of graphite and magnesia carbon bricks for industrialized ladle slag lines has been promoted and used today.
The aluminum-magnesia-carbon brick is made of bauxite or corundum as the main raw material, supplemented by an appropriate amount of fused magnesia, graphite and bonding agent, and is made by press molding and low-temperature hardening treatment. Compared with high alumina bricks, the reasons for the improved performance of aluminum-magnesia-carbon bricks are: adding a small amount of magnesia improves the slag resistance of the brick; adding a small amount of graphite improves the slag resistance of the brick and reduces the possibility of sticking.
At the same time, the alumina and magnesia in the alumina-magnesia-carbon bricks can produce magnesia-aluminum spinel with higher refractoriness at high temperatures, which improves the high-temperature stability of the bricks. Therefore, in terms of performance, aluminum-magnesium-carbon bricks have higher thermal shock stability and slag resistance than high-alumina bricks. Based on the above advantages, aluminum-magnesium-carbon bricks have been playing a role as a refractory material for steel cladding walls since the mid-1990s Important role.

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