Effect of MgO on wetting and corrosion behaviour of corundum substrate by CaO–SiO 2 –MgO (–Al 2 O 3 ) slags

Abstract

Effect of MgO content on wetting and corrosion behaviour of corundum substrate by CaO–SiO₂–MgO (−15%Al₂O₃) molten slags was investigated at 1450°C via joint application of a sessile drop technique, SEM–EDS detection and FactSage thermodynamic software. All slags exhibit good wettability on the substrate, and the contact angle values are small. Increasing MgO content from 7% to 9% in CaO-SiO₂-MgO slags can increase the contact angle between the droplet and the substrate, while the substrate dissolution thickness and the slag penetration depth tend to decrease. Increasing MgO content from 8% to 15% in CaO-SiO₂-MgO-15% Al₂O₃ slags can also increase the contact angle, but significantly decrease the slag penetration depth. The indirect dissolution thickness increases instead due to the formation of a large amount of MgAl₂O₄ by the interface reaction. The wettability can give an indication of the slag penetration depth in the substrate but not the dissolution thickness of the substrate.