Volume 110, Number 6, 2013
|Page(s)||391 - 404|
|Published online||10 January 2014|
Wear mechanisms of Al2O3-MgO spinel-forming refractories used in steel ladle impact pads
CEMHTI – Conditions Extrêmes et Matériaux Haute Température et
Irradiation, 1D Avenue de la
Recherche Scientifique, 45071
Orléans Cedex 2,
2 Ecole Polytechnique de l’Université d’Orléans, 8 rue Léonard de Vinci, 45072 Orléans Cedex 2, France
3 TRB, 7 Rue de la Neuville, 62152 Nesles, France
Accepted: 6 October 2013
Refractory castables containing alumina-magnesia/self-forming spinel (MgAl2O4) are used in impact pads of steel ladles in steelmaking processes. In order to understand the wear mechanisms of refractory materials, several recipes were tested from a corrosion, slag resistance and thermal shock point of view. The results show that the corrosion is extremely limited at the slag/refractory interface for all cases. Nevertheless, for higher cement alumina content castables, the formation of cracks is observed in refractory castables into which slag can penetrate. The slag reacts with the alumina to form a new phase such as hibonite (CA6) and calcium dialuminate (CA2). The volumetric change of these reactions involving CA2 and CA6 lead to the apparition of macro-cracks. Thus, the penetration of slag and steel are increased, causing hot mechanical properties to degrade. For lower cement alumina castables, the formation of micro-cracks is avoided by controlling volume expansion. Thus, the slag deposit reacts with alumina grains and the matrix at the slag/refractory interface to produce a monomineral layer of hibonite. In this way, the monomineral layer acts as a barrier and limits the penetration of slag and steel into the refractory lining. Thus, to increase the lifetime of refractory castables containing alumina-magnesia/self-forming spinel, it is advised to control volume expansion in order to avoid the formation of cracks and limit the penetration of secondary metallurgy steel ladle slag.
Key words: Refractories / steel ladle / impact pad / alumina-magnesia castable / wear mechanisms
© EDP Sciences 2014
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