Browsing by Author "Hubalkova, Jana"

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    GRK 2802: Characterization of a recyclate-based MgO-steel as-sintered inert anode candidate after exposure to cryolite electrolysis
    (Technische Universität Bergakademie Freiberg, 2026-02-12) Yaroshevskyi, Serhii; Adamczyk, Alexander; Brachhold, Nora; Schmidt, Gert; Hubalkova, Jana; Gumeniuk, Roman; Charitos, Alexandros; Aneziris, Christos
    The replacement of consumable carbon anodes with oxygen-evolving inert, carbon free anodes is a key technological challenge for decarbonizing primary aluminum production. While metallic, ceramic, and cermet anodes have been extensively studied, the use of recycled raw materials remains largely unexplored. In this work, composite cermet anodes consisting of 60 vol% AISI 316L stainless steel and 40 vol% recycled MgO from spent refractories were developed and tested under galvanostatic Hall-Héroult electrolysis conditions in cryolite at 1000 °C. The as-sintered composites exhibited stable cell voltage (3.2-3.3 V) over 2 h of operation. Post-mortem SEM/EDS/EBSD analyses revealed a multilayered structure with protective Fe-oxide, Al/Cr spinel formation, corroded Mg-F-rich phases, and cryolite infiltration extending beyond 2 mm depth. While the 316L steel matrix showed relative stability, the recycled MgO fraction proved chemically reactive, generating porosity and acting as the primary pathway for melt intrusion and secondary Al2O3 precipitation. Complementary static contact corrosion tests confirmed rapid fluoridation of MgO, whereas steel grains remained intact.
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    GRK 2802: Steel ceramic composite anodes based on recycled MgO–C lining bricks for applications in cryolite/aluminum melts
    (Technische Universität Bergakademie Freiberg, 2026-02-16) Yaroshevskyi, Serhii; Weigelt, Christian; Malczyk, Piotr; Roungos, Vasileios; Hubalkova, Jana; Zienert, Tilo; Kraft, Bastian; Wagner, Stefan; Aneziris, Christos
    Novel manufacturing route for composite inert anodes containing 60:40 of 316 L stainless steel and MgO powder obtained from recycled MgO-C brick material has been developed and evaluated. After burnout of residual carbon from the recycled MgO-C powder, MgO and steel were granulated and pre-sintered in order to generate agglomerates of composite material acting as coarse grains within the composite material, and thus lowering the sintering-related shrinkage. The pre-sintered granules were mixed with raw steel and MgO powder in order to achieve a high particle packing and subsequently cold isostatically pressed in the form of electrodes. All manufactured anode samples were subjected to sintering at 1350 ◦C and pre-oxidation at different temperatures – 800 °C, 900 °C, and 1000 °C. Afterwards, mechanical and electrical properties of the manufactured electrodes were characterized. The results show that upcycling of the MgO-C material enables manufacturing of sophisticated electrode products, which can be applied in the aluminum industry.