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discovered 02_2012

FOCUS// The HZDR Research Magazine WWW.Hzdr.DE 06 07 Researching liquid metals Liquid metals are the focus of the new Helmholtz Alliance LIMTECH – the acronym stands for “Liquid Metal Technologies“. The HZDR and the Karlsruhe Institute of Technology (KIT) are pooling their competencies with those of the other Helmholtz centers and universities in Germany and abroad. Liquid metals can store large amounts of energy or effectively conduct heat. They occur in many branches, e.g. in steel or light metal casting processes. Furthermore, they are becoming increasingly more important for future technologies, as for instance in new liquid metal batteries for storing energy, in the CO2 -free production of hydrogen or in the production of solar cells among others. Because liquid metals are very suitable for cooling high-energy processes, they also contribute to higher energy and resource efficiency. This is due to the fact that the degree of efficiency of thermo-dynamic processes increases with temperature. Two sub-projects of the alliance have thus also been devoted to the implementation of liquid metals in solar power plants. LIMTECH’s goal is to conduct research on liquid metal technologies for a wide range of applications that will be developed further and made available. Funding in the amount of 20 million Euros is available – 50% from the Helmholtz Association’s Initiative and Network Fund, the other 50% from the participating Helmholtz centers and partners. Within the framework of the alliance a graduate program will also be set up. Another focus is the close collaboration with partners from industry in order to apply the results to technology as quickly as possible. Participating Helmholtz centers: Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Karlsruhe Institute of Technology (KIT), Forschungszentrum Jülich (FZJ), German Aerospace Center (DLR) External partners: Technische Universität Dresden, Ilmenau University of Technology, Leibniz Universität Hannover, TU Bergakademie Freiberg, University of Potsdam, Georg-August-Universität Göttingen, RWTH Aachen, Institute of Physics Riga (Latvia), Coventry University (UK) Today discourse takes place face to face, where scientific efforts were once scoffed at for being too far removed from the harsh industrial world. Besides the steel plants, there are also one or two manufacturers of electromagnetic brakes that have become involved with the LIMMCAST plant and the first projects with partners from industry are already underway. The LIMMCAST plant offers unique possibilities for conducting fundamental experiments using an alloy that is similar to steel with respect to its thermo-physical characteristics. The experiments are carried out resembling the realistic material processes in the steel industry, even if the model metal only heats up to approx. 200 degrees Celsius. Just like in a real company there is a tundish, from which the liquid alloy is regulated using a stopper rod, before it is first poured into the submerged entry nozzle and then into the mold. The stopper rod is used to adjust the flow rate and to inject argon gas. If the metal flows out too quickly or uncontrollably from the submerged entry nozzle into the mold, then the turbulent flow carries impurities with it such as toxins or oxides, which become entrapped in the molten metal. This leads to internal material defects of the finished steel product. Furthermore, surface defects can form, if unintended interactions take place between the molten metal and the casting powder, and finally in a worst-case scenario the strand can be broken allowing the molten metal to flow out, when the rigid outer cast coating of the strand melts again due to the uncontrolled impact of the molten metal. Measuring flows directly in the molten metal “We won’t run out of ideas for experiments at LIMMCAST over the next ten years“, says Sven Eckert, Head of the Magnetohydrodynamics Division (MHD) at the HZDR. “After finding out in our experiment, which physical variable had been neglected in previous assumptions about electromagnetic brakes, we are now also using our own Gunter Gerbeth is the coordinator of LIMTECH, a new Helmholtz Alliance.