Authors:
Dr. Tony Wetzig | Technische Universität Bergakademie Freiberg | Germany
Dr. Marc Neumann | Technische Universität Bergakademie Freiberg | Germany
Leandro Schöttler | Deutsche Edelstahlwerke Specialty Steel GmbH & Co. KG | Germany
Dr. Matthias Schwarz | Deutsche Edelstahlwerke Specialty Steel GmbH & Co. KG | Germany
Prof. Dr.-Ing. habil. Christos G. Aneziris | Technische Universität Bergakademie Freiberg | Germany
In order to remove non-metallic inclusions from cast melts, steel melt filtration is a very promising technique used in the foundry and steelmaking industry. However, the application of conventional foam filters in state-of-the-art continuous casting is particularly challenging due to the long casting durations and the harsh casting conditions. Inbuilt foam filters tend to premature clogging and failure due to thermal shock or high mechanical load at high temperatures. The previously investigated immersion of exchangeable foam filters is an alternative but only if the tundish design allows for it. Thus, large-scale cellular filter components for fixed implementation at the bottom of the tundish were investigated in the present study. In order to find a suitable material, bar-shaped samples of different alumina-based refractory compositions were extruded with the aid of cellulose-based plasticizers and analyzed regarding their shrinkage behavior, density, porosity, mechanical strength and resistance against thermal shock, among others. For each property, the impact of adding coarse alumina fractions and/or zirconia and/or carbonaceous binders and fillers was evaluated. Based on the lab-scale investigations, Al2O3 – ZrO2 materials with coarser alumina fractions, showed the most promising overall performance. In a final step, both a carbon-bonded as well as a sintered oxidic version of this material were successfully applied to manufacture prototypes of large-scale filter components by random stacking of an extruded continuous strand.