TU Bergakademie Freiberg Data Publications

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Data publications from research of Freiberg University of Mining and Technology.

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Browsing TU Bergakademie Freiberg Data Publications by Author "Aneziris, Christos G."

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  • ItemOpen Access
    Corrosion and Process Analysis of a Preoxidized MgO Recyclate-based Cermet Anode in Laboratory-Scale Na-Cryolite Molten Salt Electrolysis of Aluminum at 1000 °C
    (Technische Universität Bergakademie Freiberg, 2026-07-14) Adamczyk, Alexander; Hossain, Farhan; Garcia Paz, Felipe A.; Yaroshevskyi, Serhii; Vogt, Daniel; Aneziris, Christos G.; Charitos, Alexandros
    The development of inert anodes for aluminum electrolysis remains challenging due to the high corrosivity of cryolite-based melts at 950°C–1000°C. This study investigates the corrosion and process behavior of a carbon-free MgO–steel cermet anode derived from refractory recycling during laboratory-scale Na-cryolite electrolysis at 1000°C, focusing on the effect of a pre-oxidation treatment on its corrosion behavior. In the as-sintered state, MgO grains are mechanically bonded to a 316L steel matrix with interfacial porosity that limits corrosion resistance. Pre-oxidation at 900°C for 24 h forms a dense Mg–M–O (M=Fe, Cr) oxide-rich surface layer, sealing pores and improving resistance to cryolite infiltration, albeit at the cost of reduced electrical conductivity, which translated into an overall higher cell voltage compared to the as-sintered state. During electrolysis, this layer degrades under anodic polarization, O2 evolution, and fluorination. The surface transforms into a Fe–O-rich magnetite layer (Fe3O4), while a Cr-containing oxide and an in situ Mg–Fe–O transition zone form beneath, maintaining partial protection. Overall, pre-oxidation effectively delays electrolyte penetration by converting MgO into new oxide phases but introduces conductivity losses and surface instability. The results highlight both the potential and limitations of MgO-based cermet anodes for sustainable aluminum production.
  • ItemPublic Metadata
    GRK 2802: HIGH-TEMPERATURE COMPRESSION TESTS AND ACCOMPANYING SEM INVESTIGATIONS OF MgO-C REFRACTORIES BASED ON FRESH MgO AND RECYCLATE
    (Technische Universität Bergakademie Freiberg, 2025-08-27) Schramm, Alexander; Weidner, Anja; Biermann, Horst; Stadtmüller, Till M. J.; Aneziris, Christos G.; Schemmel, Thomas
    With regard to the increasingly desired recycling of refractories, the properties of MgO-C containing recyclate are of high economic and ecological relevance. Two commercially available grades were studied to evaluate the influence of recyclate in MgO-C materials: MgO-C consisting only of fresh MgO as well as MgO-C with 50 wt.% recyclate. In this study, compression tests on these MgO-C materials were performed at room temperature, 1000°C and 1300°C. In order to investigate the microstructure and to identify the occurring damage mechanisms, scanning electron microscopy (SEM) investigations were carried out. The compression tests provided higher strengths at room temperature and at 1000°C for the MgO-C grade with recyclate compared to the grade with only fresh MgO and comparable strengths at 1300°C. Thus, the use of recycled agglomerates had no negative effect on the compressive strength.
  • ItemOpen Access
    The Influence of Biomass Cokes on the Microstructure and Thermal Shock Resistance of MgO-C Refractories
    (Technische Universität Bergakademie Freiberg, 2026-09-21) Gehre, Patrick; Kapessov, Magzhan; Guhl, Stefan; Gräbner, Martin; Aneziris, Christos G.
    In this study, biomass cokes from sunflower seed hull (SFSH) and wood pellets (WP) were added to a MgO-C batch (3 mass % C) to replace 1.1 mass % of graphite. After hardening and carbonizing the samples, the influence of the biomass cokes on the microstructure and thermal shock resistance was investigated. The replacement of flaky graphite by carbonized WP and SFSH reduced the bulk density and increased the apparent porosity after pressing and carbonization, but the degree was only marginal. This was confirmed by SEM investigations, where the biomass-coke containing samples exhibited a microstructure with a higher amount of pores between the fine MgO grains. The thermal shock resistance of the porous wood pellet coke containing MgO-C is at the same level as the reference sample but not superior to it.