Technische Universität Bergakademie Freiberg

Permanent URI for this communityhttp://opara.zih.tu-dresden.de/handle/123456789/16

Research data repository of Freiberg University of Mining and Technology.

Browse

Browsing Technische Universität Bergakademie Freiberg by Author "Andrä, Stefan"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • ItemPublic Metadata
    GRK2802: Effect of microporous Al2O3-MgAl2O4 content on the thermal shock resistance and molten steel purification performance of β-SiC whisker-reinforced Al2O3-MgAl2O4-C ceramic filters
    (Technische Universität Bergakademie Freiberg, 2026-04-27) Song, Jinwen; Yan, Wen; Volkova, Olena; Andrä, Stefan; Bellé, Matheus Roberto; Neubert, Lukas; Tian, Can; Li, Yuanbing
    This study investigates the effect of microporous Al2O3-MgAl2O4 content on the phase composition, microstructures, mechanical properties, and purification performance for molten steel of Al2O3-MgAl2O4-C filters, conducted through XRD, SEM, EDS, immersion test with molten steel, and so on. The results indicate that the microporous Al2O3-MgAl2O4 raw material significantly promotes the formation of in-situ β-SiC whiskers within the filters, which intertwine among the particles and grow within the microporous structure, working synergistically with the MgAl2O4 phase to improve the strength and thermal shock resistance. Regarding molten steel purification, on the one hand, the microporous structure of Al2O3-MgAl2O4 particles enhances the filter’s contact area with molten steel, imparting a higher physisorption efficiency to the filter. On the other hand, MgAl2O4 has a greater tendency for carbothermal reactions, generating Mg vapor that has a strong chemisorption capability for [Al], [O], and Al2O3 inclusions in the molten steel. The microporous structure and MgAl2O4 facilitate the formation of a MgAl2O4 reaction layer at the interface during immersion test, contributing to the purification of the molten steel. The filter AM60, prepared with 60 wt% microporous Al2O3-MgAl2O4 powder, not only exhibits excellent thermal shock resistance (with a cold compressive strength of 0.54 MPa and a strength of 0.59 MPa after three thermal shock tests), but also demonstrates a high purification efficiency (reducing inclusions in steel by 68%, and lowering the total oxygen content from 56.3 ppm to 13.5 ppm). Finally, the formation mechanism of in-situ β-SiC whiskers, the role of microporous Al2O3-MgAl2O4 raw material in purification function, and the comprehensive molten steel purification mechanism were proposed.
  • ItemPublic Metadata
    GRK2802: Wetting behavior and interfacial reactions of molten steel in contact with the Al2O3-MgAl2O4-C substrate: Effect of porous Al2O3-MgAl2O4 raw material
    (Technische Universität Bergakademie Freiberg, 2026-04-27) Song, Jinwen; Wen, Yan; Volkova, Olena; Wang, Qinghu; Bellé, Matheus Roberto; Neubert, Lukas; Andrä, Stefan
    This paper investigates the wetting behaviors of molten steel in contact with the Al2O3-MgAl2O4-C (Abbreviated as AM) and Al2O3-C (Abbreviated as A) substrates respectively by the sessile drop wetting method, and thoroughly discusses the interfacial reaction mechanism. In the initial stage of the wetting experiment, the initial contact angle between the molten steel and substrate AM (121°) was significantly smaller than that with substrate A (129°). As the carbothermal reactions proceeded in the substrate, gaseous products accumulated in the micropores of substrate AM, rose into the molten steel and were subsequently expelled. This process caused the molten steel droplet to shake and move on the surface of substrate AM, leading to instability in the contact angle, which fluctuated with time but exhibited an overall increasing trend. In contrast, the contact angle between the molten steel and substrate A remained relatively stable, with no significant gas expulsion observed. During this period, the reducing gases generated by the carbothermal reactions in substrates rose and formed distinct reaction layers at the molten steel/substrate interfaces gradually. A MgAl2O4 layer was observed at the interface between the molten steel and substrate AM. Notably, this reaction layer exhibited a dense and continuous structure in the middle area but became porous and discontinuous in the edge area. By comparison, an Al2O3-Al6Si2O13 layer was detected at the interface between the molten steel and substrate A. Following the formation of reaction layers, the contact angle between the molten steel and substrate AM gradually increased and eventually stabilized at 139°, which was higher than the final stable contact angle (130°) between the molten steel and substrate A. Finally, the comprehensive wetting behavior and the interfacial reaction mechanism were proposed.