Wettability of Al₂O₃ substrate by liquid iron. Effects of oxygen in liquid iron and purity of Al₂O₃ substrate

The interfacial properties between liquid Fe-O alloy and alumina substrates with different purities, 99.9% and 96%Al₂O₃, were measured by the sessile drop method. The interfaces of samples after the experiment were examined by SEM and EPMA. It was found that the contact angle increased and the work of adhesion decreased with increasing oxygen concentration in the iron in the range of less than 0.010%. These phenomena were attributed to the dessociation of Al₂O₃. For 96%Al₂O₃, the Ca and Mg rich layer was observed at the Fe-Al₂O₃ interface. Whereas, at higher oxygen concentrations, the contact angle decreased with increasing oxygen concentration. Under these conditions, the formation of the hercynite or the penetration of iron into the grain boundaries of Al₂O₃ substrates were observed.