The present study investigates the wetting and corrosion behaviour of slags
on dense Al2O3 ceramics, focusing on the influence of varying vanadium- and
titanium oxide content. Physicochemical properties of the slag were assessed
by measuring wetting angles, heights and diameters of the molten slags on
the alumina at different temperatures. Microscopic observations and
elemental composition analysis were conducted on the interface between the
corroded Al2O3 ceramics and the slags. Our findings demonstrated that the
V2O3 addition in the slag leads to its oxidation to V2O5, which further
reacts with Fe2O3 and MnO to form low melting point phases such as FeVO4 and
MnVO6. Consequently, the melting point of the slag decreases significantly,
resulting in a decreased wetting angle with the Al2O3 ceramics. The presence
of unsaturated alumina in the slag leads to the dissolution of aluminium
ions from the ceramics into the slag, which reacts with Fe2O3 and MnO to
form spinel phases, contributing to material loss of the ceramics.
Infiltration of the slag into the Al2O3 predominantly occurs through the
alumina grain boundaries. Two types of infiltration are identified: one
involving reactions with alumina to form low melting point phases like Fe2O3
and the other involving inherent low melting point phases such as MnVO6. In
contrast, the penetration of SiO2 into the alumina substrate is limited.
Additionally, the dissolution of Al2O3 into the slag creates pathways for
further infiltration. This study highlights the significant influence of Ti
and V content on the physicochemical properties of the slag and provides
insight into the corrosion mechanism of Al2O3 ceramics by Ti and V
containing slags.