Aluminum Electrolysis: TiB2 Wettable Cathodes by Suspension Plasma Spray

In the process of aluminum production, electrolysis is a key step in terms of energy consumption and greenhouse gas emission. In order to reduce this consumption and increase process efficiency, several tracks have been explored in the past decades. One of them is using inert anodes coupled with so-called wettable cathodes. The most promising material for wettable cathodes in the harsh electrolysis environment is titanium diboride. Unfortunately, it has proven to be very hard to make bulk TiB₂ cathodes due partly to the poor sintering ability of the material. Though atmospheric plasma spray (APS) has been already tried to deposit this material on the cathode, it has not yet proven itself an efficient tool to do so, especially as TiB2 oxidizes easily during deposition, depriving the coating from its most interesting properties. In this study, we investigate the deposition of TiB₂ by axial injection suspension plasma spray process. This process has the potential of depositing dense or columnar coating structures while limiting the in-flight oxidation of the spray material.