Thermal shock- and corrosion-resistant heat-insulating composites based on renewable raw materials for application in steel ingot casting
Final Report Abstract
In this project, a new composite material was developed using a thermal insulation material based on the natural raw material rice husk ash (RSA), which was functionalized for use in the steel casting process through flame spraying. Initially, a comprehensive characterization of various RSA substrate materials was conducted, focusing on their high-temperature properties and stability. It was found that material variants with a high SiO2 content (>94 wt.%) exhibited sufficient refractoriness up to 1600 °C. However, a strong non-linear thermal expansion of the RSA substrate material was also observed, which was attributed to a phase transformation from α- to β-cristobalite in the temperature range of 250 °C to 280 °C. Subsequently, the properties of flame-sprayed layers of Al2O3, Al2O3-TiO2, and Al2O3-TiO2-ZrO2 (such as resulting layer thickness, strength distribution, Young's modulus, R-curve behavior, subcritical crack growth, and thermal expansion) were thoroughly characterized, with a correlation to the spray parameters. Following this, composite materials were produced and characterized in terms of microstructure, layer adhesion, and oxidation resistance. The analysis showed sufficiently high layer adhesion, which was attributed to the interlocking of the flame-sprayed layer with the rough RSA substrate surface. Dipping tests of fully coated prisms into molten steel (1600°C) confirmed the high-temperature stability and thermal shock resistance of the composite material. Finally, runner-brick prototypes (105 x 105 x 250 mm³) in cooperation with the industrial partner were produced, coated by flame spraying, and successfully tested with molten steel, i.e., without leakage. The solidified steel blocks were analyzed for their population of non-metallic inclusions. For this purpose, a generally applicable routine for inclusion analysis was developed using automated feature analysis (automated scanning electron microscopy), including comprehensive detailed and statistical evaluation. The results of the casting tests even showed a slightly lower number of inclusions for the steel after contact to the newly developed composite material compared to the fireclay-based reference material.
Link to the final report
https://nbn-resolving.org/urn:nbn:de:bsz:105-qucosa2-956383
Publications
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Automated feature analysis as a tool for non-metallic inclusion analysis in solidified metals. Open Ceramics, 16, 100452.
Kerber, Florian; Neumann, Marc; Dudczig, Steffen; Schmidt, Gert; Hubálková, Jana & Aneziris, Christos G.
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On the Statistics of Mechanical Failure in Flame-Sprayed Self-Supporting Components. Ceramics, 6(2), 1050-1066.
Kerber, Florian; Hollenbach, Magda; Neumann, Marc; Wetzig, Tony; Schemmel, Thomas; Jansen, Helge & Aneziris, Christos G.
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“Application of flame-sprayed ceramic coatings on silica-based insulating refractories for steel ingot casting”, XVIIIth Conference of the European Ceramic Society (ECERS), Lyon, Frankreich, 02. – 06. Juli 2023
F. Kerber, M. Neumann, T. Zienert, T. Schemmel, H. Jansen & C.G. Aneziris
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“Characterization of inclusion populations in metal matrix using automated feature analysis”, Unified International Technical Conference on Refractories (UNITECR) 18th Biennial Worldwide Congress on Refractories, Frankfurt am Main, Germany, 26. – 29. September 2023
F. Kerber, M. Neumann, J. Hubálková, G. Schmidt, T. Schemmel, V. Stein, H. Jansen & C. G. Aneziris
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Impact of thermal shock on the R-curve and subcritical damage behaviour of flame-sprayed alumina compounds. Journal of the European Ceramic Society, 44(5), 3418-3428.
Neumann, Marc; Hubálková, Jana; Kerber, Florian; Gehre, Patrick; Jelitto, Hans & Aneziris, Christos G.
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Insulating refractories based on rice husk ashes functionalized by flame-sprayed alumina coatings for steel ingot casting. Journal of the European Ceramic Society, 44(12), 7296-7309.
Kerber, Florian; Zienert, Tilo; Neumann, Marc; Malczyk, Piotr; Schemmel, Thomas; Jansen, Helge & Aneziris, Christos G.
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Robot-aided tailoring of flame spray coatings for high-temperature barrier application. Open Ceramics, 17, 100558.
Neumann, Marc; Kerber, Florian; Bock-Seefeld, Benjamin; Schemmel, Thomas; Jansen, Helge & Aneziris, Christos G.
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“Shaped Insulating Refractories Based on Rice Husk Ashes Functionalized with a Flame- Sprayed Alumina Coating for Steel Ingot Casting” REFRA PRAGUE: The 22nd conference on modern refractory materials and key achievements in high-temperature technologies, Prag, Tschechien, 22. – 24. Mai 2024
F. Kerber, T. Zienert, M. Neumann, T. Zienert, T. Schemmel, H. Jansen & C.G. Aneziris
