Wettability of Solid Metals by Molten MnO-SiO₂ Slag

An article presents results of a study of wetting of iron, nickel, and platinum substrates by molten MnO-SiO₂ slag of near-eutectic composition by the sessile-drop method in reducing atmosphere (oxygen partial pressure of 10⁻²⁰ to 10⁻¹⁸ atm). Significant MnO reduction and manganese dissolution into substrate was observed in reactions with all three substrates. Silica also was reduced in reaction with Fe and Ni, although the extent of reduction was much smaller in comparison with MnO and was not observed in reaction with Pt. The dissolution of manganese led to modification of the interface with formation of molten phase for nickel and platinum substrates. Terminal contact angles (after 240 minutes) for MnO-SiO₂ slag were as follows: for iron substrates—5 ± 2 deg at 1350 °C, 9 ± 2 deg at 1390 °C, and 6 ± 2 deg at 1450 °C; and for platinum—15 ± 2 deg at 1350 °C and 1390 °C, and 12 ± 2 deg at 1450 °C. The contact angle for the Ni- (MnO-SiO₂) system was close to zero—3 ± 2 deg at 1350 °C and 1390 °C. Modification of the metal-oxide interface as a result of reduction of oxides and adsorption of oxygen made wetting dynamic and affected interfacial properties.