GRK 2802: Wetting behavior and interfacial reactions of molten steel in contact with the Al2O3-MgAl2O4-C substrate: Effect of porous Al2O3-MgAl2O4 raw material

Abstract

This paper investigates the wetting behaviors of molten steel in contact with the Al2O3-MgAl2O4-C (Abbreviated as AM) and Al2O3-C (Abbreviated as A) substrates respectively by the sessile drop wetting method, and thoroughly discusses the interfacial reaction mechanism. In the initial stage of the wetting experiment, the initial contact angle between the molten steel and substrate AM (121°) was significantly smaller than that with substrate A (129°). As the carbothermal reactions proceeded in the substrate, gaseous products accumulated in the micropores of substrate AM, rose into the molten steel and were subsequently expelled. This process caused the molten steel droplet to shake and move on the surface of substrate AM, leading to instability in the contact angle, which fluctuated with time but exhibited an overall increasing trend. In contrast, the contact angle between the molten steel and substrate A remained relatively stable, with no significant gas expulsion observed. During this period, the reducing gases generated by the carbothermal reactions in substrates rose and formed distinct reaction layers at the molten steel/substrate interfaces gradually. A MgAl2O4 layer was observed at the interface between the molten steel and substrate AM. Notably, this reaction layer exhibited a dense and continuous structure in the middle area but became porous and discontinuous in the edge area. By comparison, an Al2O3-Al6Si2O13 layer was detected at the interface between the molten steel and substrate A. Following the formation of reaction layers, the contact angle between the molten steel and substrate AM gradually increased and eventually stabilized at 139°, which was higher than the final stable contact angle (130°) between the molten steel and substrate A. Finally, the comprehensive wetting behavior and the interfacial reaction mechanism were proposed.