LAUSR

Abstract The effects of the surface roughness, carbon content and the additions of carbon nanotubes (CNT) and alumina nanosheets (ANS) on the wettability of molten steel on Al2O3 substrates with and without Al2O3(-C) coatings were investigated by the sessile drop wetting method, SEM and EDS, etc. At the beginning of the wetting experiment, the contact angle increased with an increasing surface roughness. With a longer wetting time, the interfacial reactions between the coatings and molten steel became more influential on the contact angles. When the coatings contained 30 wt% carbon, a new layer presumably consisting of hercynite (FeAl2O4) was formed at the substrate/steel interface stabilizing the contact angles with time. Moreover, compared to the coatings without nano-additives, the additions of CNT and ANS promoted the reactions at lower temperatures and resulted in a faster stabilization of the contact angles. Finally, the interfacial wetting and reaction mechanisms were proposed.