Gunning materials are used as a dispensable protective layer to extend the tundish life. Their use however, affects the steel cleanliness by introducing steel reoxidation and exogenous inclusions. In the present work, the interaction between molten steel and three types of refractory, i.e. MgO, Al_(2)O_(3), and MgO + 2MgO?SiO_(2) based gunning materials (GM) have been investigated. Compared to MgO and MgO + 2MgO?SiO_(2) GM, the Al_(2)O_(3) GM exhibited better infiltration resistance to molten steel. The two phase MgO + 2MgO?SiO_(2) GM was found to be less prone to steel infiltration than single-phase MgO GM. The compositional evolution of steel influenced by gunning material was experimentally measured and also predicted with thermodynamic equilibrium calculations. The steel cleanliness in terms of inclusion size, number density, area fraction and morphology was measured and evaluated. Although large Al_(2)O_(3)/AlTiO_(X) inclusions were formed through the erosion of Al_(2)O_(3) GM, the use of Al_(2)O_(3) GM resulted in an improved steel cleanliness due to its lower content of reducible compounds compared to that of MgO and MgO + 2MgO?SiO_(2) GM.
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