Effect of nano-carbon black content on wetting phenomenon of molten steel and alumina–carbon ceramic filter substrates

The effect of nano-carbon black content (0, 8 and 12 wt.%) on the wettability of molten steel on Al₂O₃–C substrates was investigated by the sessile drop wetting method at 1500 °C under argon atmosphere. At the beginning of the wetting experiment, the contact angle decreased with the increase in nano-carbon black content. As the wetting experiment progressed, FeAl₂O₄ layer and sheet Al₂O₃ layer were found at the interface between the molten steel and the Al₂O₃–C substrates with 0 and 8 wt.% nano-carbon black content, and the contact angle deceased with time. When the content of nano-carbon black was 12 wt.%, a large number of nano-Al₂O₃ whiskers were observed, which made the contact angle between the molten steel and Al₂O₃–C substrate become large. Based on the scanning electron microscope and energy dispersive spectrometry results, the formation mechanism of FeAl₂O₄ layer and Al₂O₃ layer and the interfacial reaction mechanism were proposed.