Browsing by Author "Yan, Wen"

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    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.
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    GRK2802: Enhanced strength and high reactivity of Al2O3-MgAl2O4-C ceramic filters with in-situ β-SiC whiskers: Role of nano-Al2O3
    (Technische Universität Bergakademie Freiberg, 2026-04-27) Song, Jinwen; Yan, Wen; Volkova, Olena; Cheng, Zhenyu; Neubert, Lukas; Angelini, Alberto; Bellé, Matheus Roberto; Li, Yuanbing
    The role of nano-Al2O3 content on the phase composition, microstructure, mechanical properties, and purification performance for molten steel of Al2O3-MgAl2O4-C ceramic filters was investigated through XRD, SEM, EDS, as well as immersion test with molten steel. Results indicate that nano-Al2O3 firstly improves slurry retention performance, increases filter strut thickness, and ensures uniform distribution without cracks. Furthermore, during the sintering process, nano-Al2O3 accelerates the mass transfer (Mg2+ and Al3+) between microporous Al2O3-MgAl2O4 particle and nano-Al2O3 due to its high sintering reactivity, which promotes the development and growth of neck connections among the microporous Al2O3-MgAl2O4 particles, resulting in a substantial improvement in the mechanical properties. Regarding molten steel purification, on the one hand, its high reactivity significantly promoted the carbothermal reduction reaction, generating reductive gases that interact with and adsorb [Al], [O], and Al2O3 inclusions in the molten steel, quickly forming a continuous and uniform Al2O3-MgAl2O4 reaction layer at the interface. On the other hand, high mechanical strength also improves filter’s resistance to molten steel erosion and avoids contamination of the molten steel. Together, these two effects synergistically contribute to the purification of molten steel. The filter N5, with 5 wt% nano-Al2O3, not only exhibits excellent mechanical properties with a cold compressive strength of 1.41 MPa and 1.21 MPa after three thermal shock tests, but also demonstrates high purification efficiency, reducing inclusions by 44% and lowering the total oxygen content from 56.3 ppm to 26.1 ppm. Finally, the role of nano-Al2O3 in sintering behavior and purification function, as well as the comprehensive molten steel purification mechanism were proposed.