Browsing by Author "Kerber, Florian"

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    GRK 2802: Investigations on the corrosion of 316L steel composite materials with MgO/TiO2 ceramic immersed in molten cryolite
    (Technische Universität Bergakademie Freiberg, 2026-06-25) Yaroshevskyi, Serhii; Weigelt, Christian; Kerber, Florian; Brachhold, Nora; Zienert, Tilo; Adamczyk, Alexander; Vogt, Daniel; Charitos, Alexandros; Aneziris, Christos G.
    Composites based on a steel with 40 vol% magnesia or titania were produced with the ceramics-derived extrusion and pressureless sintering. The materials were tested in a laboratory-scale fused-salt electrolysis cell with a synthetic cryolite in order to identify their potential use as electrode material in the Hall-Heroult process. The highly corrosive atmosphere and salt melt initiated certain corrosion effects in both material variants. The corrosion depth was determined with 1160 μm for magnesia and 463 μm for titania, respectively, after 8 h corrosion test. The initial corrosion includes the complete penetration of the specimens with cryolite and the dissolution of the ceramic component. A pre-oxidation of the specimens containing magnesia depressed the corrosion depth by 75% due to the formation of an aluminium oxide layer in the composite material during corrosion tests. The reduction in corrosion depth by pre-oxidation was less ronounced for the TiO2 composite materials (- 15%).
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    GRK 2802: Population of Nonmetallic Inclusions in Liquid High-Silicon Electrical Steel in Contact With MgO–C Refractories Based on Recyclates and Environmentally Friendly Binders
    (Technische Universität Bergakademie Freiberg, 2026-05-29) Neubert, Lukas; Bellé, Matheus Roberto; Kerber, Florian; Gunasekar, Dinesh Kumar; Weddige, Hans-Jörn; Aneziris, Christos G.; Volkova, Olena
    Nonmetallic inclusions (NMIs) are integral constituents of ferrous materials, but almost always have a negative impact on their properties. Therefore, it is best to implement strategies during production to avoid NMIs as much as possible or at least control their formation. To gain a better understanding of these mechanisms, this study investigated the population of nonmetallic inclusions in liquid high-silicon electrical steel (Si 3 mass-%) depending on the contact with different MgO–C refractories. Both conventional refractory materials and those containing MgO–C recyclate and environmentally friendly binder systems, such as collagen, fructose, and lignin, were considered. Immersion tests were carried out for 30min at a temperature of 1600°C in accordance with DIN CEN/TS 15418. Surface phenomena, diffusions reactions, and corrosion mechanisms occurring in the refractory materials were characterized after the tests using SEM and EDX analyses. The change in the chemical composition of the steels was determined using spark spectroscopy, and the NMI population was evaluated after the tests using an automated feature analysis (AFA).
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    GRK2802: Non-metallic Inclusion Evolution in Interaction of Al-killed Mn-B Steel with Desulfurization Slag and MgO-C Refractories Containing Environmentally Friendly Binders and Recyclates
    (Technische Universität Bergakademie Freiberg, 2026-05-20) Bellé, Matheus Roberto; Neubert, Lukas; Yehorov, Anton; Kerber, Florian; Gunasekar, Dinesh Kumar; Salpagarov, Eldar; Aneziris, Christos G.; Volkova, Olena
    The high-temperature interaction between Al-killed Mn-B steel, desulfurization slag, and carbon-bonded magnesia refractories containing conventional, environmentally friendly binders and recyclate systems was systematically investigated using finger immersion testing at 1600 °C for 30 minutes. Chemical analysis of steel and slag, combined with SEM/EDX characterization of refractory/steel/slag interfaces and non-metallic inclusions (NMIs), was performed to interpret reaction mechanisms and the evolution of inclusions. Significant slag modification occurred during testing, characterized by MgO enrichment, CaO and Al2O3 depletion, and the formation of Fe- and Mn-bearing oxides. In the steel, pronounced decarburization, sulfur increase, boron depletion, and enhanced oxygen and nitrogen contents were observed, indicating reoxidation and interfacial reactions. Independent of refractory condition, MgAl2O4 spinel and Ca2SiO4 phases were detected in the infiltrated refractory zone. Refractories containing recyclates and alternative binders chemically modified the inclusion population and significantly increased NMI number density, particularly Mn-Si-Ti-based inclusions. The results demonstrate that refractory composition strongly influences slag chemistry, inclusion characteristics, and steel cleanliness. These findings provide a new understanding of refractory-slag-steel interactions during secondary metallurgy and highlight the need for optimized slag/refractory formulations to ensure inclusion control and steel quality under increasingly sustainable material strategies.