Effect of Al Content in Steel on Interfacial Interaction between Molten Steel and MgO Substrate

Abstract

The apparent contact angles between the molten steel with different [Al] contents (w[Al]) from 0.002% to 0.831% (mass fraction) and the microporous MgO (MM) substrates are measured at 1823 K using the sessile drop method. In particular, the contact angles of No. 1 (w[Al] = 0.002%) and No. 5 (w[Al] = 0.831%) molten steels gradually increase with time at the initial stage. As w[Al] increases from 0.002% to 0.831%, the transformation route of interfacial products between molten steel and the MM substrate is MgO–FeO → MgO·Al2O3 → CaO·2Al2O3 + MgO·Al2O3. The w[Al] of No. 1 molten steel is small, and the dissolution of CaO·ZrO2(s) in the substrate is mainly affected by FeO. As w[Al] increases gradually, [Al] consumes the (MgO) contained in CaO·MgO·SiO2 (CMS), and turns the CMS into (CaO·SiO2) slag layer, which promotes the CaO·ZrO2(s) dissolving and thus increasing the interaction area percentage. When w[Al] is 0.831%, [Al] can react with (CaO·SiO2) slag layer or CaO·ZrO2(s) to form CaO·2Al2O3(s).