Browsing by Author "Malczyk, Piotr"

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GRK 2802: Pre‐oxidized Recycled MgO–Steel Composite Material for Possible Application in Cryolitic Melts
(Technische Universität Bergakademie Freiberg, 2026-02-16) Yaroshevskyi, Serhii; Brachhold, Nora; Malczyk, Piotr; Gehre, Patrick; Aneziris, Christos
Recycled MgO–C lining bricks and 316L stainless steel are used to manufacture composite material for inert anode samples for aluminum electrolysis cell. The microstructure of the composite material is characterized after preoxidation thermal treatments at 800, 900, and 1000 °C as well as in its sintered state. Preoxidation (PO) process is designed to enhance the material's corrosion resistance in molten cryolite environments by developing robust Fe–Mg–O, Fe–Cr–O- containing phases. Analytical techniques including scanning electron microscopy, electron backscatter diffraction, and energy dispersive X-ray spectrometry are applied to characterize the phase formation, revealing the potential of these composites for use as inert anodes in aluminum electrolysis cells. PO at 800 °C is not sufficient to form adequate protective oxide layers. Whereas, PO at 900 and 1000 °C leads to the formation of protective oxide layers containing Mg–O Fe–O halite-like solid solutions and (Cr,Fe)3O4 spinel phase. Sample, preoxidized at 1000 °C is sealed in Mg–Fe–O spinel phase.
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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.
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SPP 2419: 3D printing of alumina components via Fused Granulate Fabrication technology and solvent-free debinding of highly filled feedstocks comprising (LD)-polyethylene and cellulose
(Technische Universität Bergakademie Freiberg, 2026-03-30) Brachhold, Nora; Heuer, Claudia; Bock-Seefeld, Benjamin; Kaiser, Patricia; Weigelt, Christian; Malczyk, Piotr; Trimis, Dimosthenis; Aneziris, Christos G.
This study focuses on the development of components in gyroid structure based on alumina as integral part of the novel burner designed for the non-premixed combustion of ammonia. During application, the component has to withstand repeated thermal shocks of approx. 600 K or more. Due to the high geometric complexity of the gyroid structure and the need for lightweight design with both macroporous regions and microporous features only the 3D printing was suitable as manufacturing technology; in the present work Fused Granulate Fabrication was used. The manufacturing routine for the employed granules with special regard to the binder system is developed. A customized thermal debinding regime without wick or solvent debinding is presented. Challenges such as the formation of bubbles and the swelling of the samples during thermal debinding were met by adjusting the printing parameters to create porosity and cavities between the deposited strands during 3D printing. Sintered bars fabricated using optimized printing parameters had a shrinkage of 13 %, an open porosity of 41 % and a flexural strength of 50 MPa, respectively. These values are sufficient for the application of the components in the novel burners. As last part of this work sheet-gyroid structures were prepared using a 1.0 mm and 0.4 mm nozzles. These structures successfully survived 5 thermal shock cycles, each involving heating to 1100 ◦C followed by air quenching, which is an excellent result in terms of thermal shock performance.