Interactions between 3Al₂O₃·2SiO₂, CA₂, CA₆, and Molten Slags

Abstract

Herein, the interaction between the oxide substrates (mullite (3Al2O3·2SiO2), calcium aluminates CaO⋅2Al2O3 (CA2) and CaO⋅6Al2O3 (CA6), and the slags with various basicities (CaO/(Al2O3 + SiO2) (1.0, 0.9, and 0.8)) and MgO (5 and 10 wt%) is investigated. The contact angle of the molten slag on oxide substrates is found to be strongly regulated by the several factors including the chemical composition of the slag, the newly formed reaction product between molten slag and substrates, and the porosity of the substrates. For the case of mullite substrate, the slags infiltrated the substrates, with various morphologies of alumina observed within the penetrated layer of the mullite. In contrast, the CA2 substrate showed less penetration compared to the other substrates. Nevertheless, the newly generated CaAl2O4 phase was detected within the pores of CA2 substrate. During the interaction of slag and CA6 substrate, the CaAl2O4 and melilite phases are identified. The presence of MgO in the slag leads to the generation of MgAl2O4 phases. The corrosion depth is found to be enhanced via basicity. Furthermore, the solidified slags with 10 wt% MgO addition are found to have noticeable porosities. The porous structure is elucidated by the decreased slag density attributed to the generation of MgAl2O4 phase.