Cermet composites based on MgO-recyclates and 316L stainless steel as carbon-free anodes for the Hall-Héroult-Process

Summary:

This work investigates MgO-316L composites as candidate inert anodes for aluminium electrolysis in cryolite melts, focusing on the influence of processing and pre-oxidation on microstructure and functional properties. The composites exhibit a two-phase structure, with conductivity governed by the metallic network. Pre-oxidation alters phase composition and porosity, promoting oxide formation and increasing brittleness. Electrolysis at 1000 °C shows that MgO undergoes fluorination and dissolution; however, corrosion progresses gradually, maintaining electrical contact through continuous exposure of the metallic phase. Intermediate pre-oxidation reduces corrosion, while excessive oxidation impairs conductivity. The results demonstrate that stable operation is achieved through controlled degradation governed by thermodynamics and microstructure.