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6428 |
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Tungsten coatings for tokamak first wall |
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Jan Cizek / Czech Academy of Sciences, Czech Republic Monika Vilemova / Institute of Materials Science and Engineering, Brno University of Technology, Czech Republic Jakub Klecka/ Institute of Plasma Physics, The Czech Academy of Sciences, Czech Republic Jan Kondas/ Institute of Plasma Physics, The Czech Academy of Sciences, Czech Republic Martin Koller/ Institute of Plasma Physics, The Czech Academy of Sciences, Czech Republic Frantisek Lukac/ Institute of Plasma Physics, The Czech Academy of Sciences, Czech Republic Tomas Chraska*/ Czech Academy of Sciences, Czech Republic Reeti Singh/ , |
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Numerous obstacles are still to be resolved in the process of using power sources based on nuclear fusion in tokamaks. Tokamak is a toroidal vessel for confining hot plasma by strong magnetic fields. The major challenge is the selection and fabrication of suitable materials as plasma facing components inside the vessel. Thermal spraying of these components to form dense coatings of W, or W-Cr-based alloys is one plausible route. So far, the attempts for such coatings formation failed due to oxidation, high porosity, insufficient adhesion, high specific surface, or even insufficient thickness. Both cold spraying and inductively coupled radio frequency plasma (ICP-RF) spraying seem promising technologies for the task. In our study, we demonstrate a successful fabrication of thick W, W-Cr and W-Cr-Ti coatings prepared by cold spray without oxidation of the metals. To date, the produced mixed coatings contained the highest levels of W ever achieved. Even more importantly, a deposition of 80 µm thick coatings of 100% pure W was demonstrated for the first time too. All coatings exhibited high hardness levels, good interface quality with substrates of three different hardness and, importantly, a promising potential for desirable oxidation resistance by formation of Cr2WOx scales. Initial tungsten-steel and tungsten-chromium composites were prepared by ICP-RF spraying. |