Título

Tecnologia de refratários alumina-magnésia para panela de aço parte ii, propriedades de concreto em aquecimento sob restrição

TECHNOLOGIES OF ALUMINA-MAGNESIA REFRACTORIES FOR STEEL LADLES PART II, CASTABLE PROPERTIES UNDER RESTRAINED HEATING

Autoria

Nakabo, Kazuya; Nishida, Shigefumi; Kitamura, Masatsugu

DOI

10.5151/1516-392X-30176

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Resumo

In this article, influences of restraint and MgO content on densification of alumina-magnesia castable during heating were experimentally studied. High thermal expansion-alumina-magnesia castable specimens were surrounded by low thermal expansion-alumina-silica castables, and heated in an electric furnace. Doing so allows restrained heating of alumina-magnesia castable. According to the results of simple calculations, the restraint stresses were estimated to be between 2 to 20 MPa, so the experimental conditions were considered reasonable. As a result of the experiments, it was verified that restraint densifies alumina-magnesia castable, resulting in an increase in modulus of rupture and modulus of elasticity. The densification effect of restraint became larger as the MgO content increased. The effects are attributable to an in-situ spinel forming reaction, which improves corrosion resistance. Taking the temperature distribution in the castable lining into account, large restraint stress is expected for the hot face while only a little effect is expected for back end. Thus, excessive difference in material property in the thickness direction, which is undesirable in terms of structural spalling, is a concern. Hence, the MgO content of alumina-magnesia castable should be determined carefully, taking not only corrosion resistance but also spalling resistance into consideration.

 

Palavras-chave

Refratários, concretos, panela de aço, comportamento térmico

Refractories, Castable, Steel ladle, Thermal behavior