The influence of vanadium and titanium oxides in slag on the wetting and corrosion of dense Al2O3 ceramics

Abstract

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.