München 2019 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 12: Plasma Surface Interaction II - Helmholtz Graduate School IV

P 12.4: Vortrag

Dienstag, 19. März 2019, 17:30–17:45, HS 20

Modelling of chemical vapor deposition (CVD) to improve tungsten fiber reinforced tungsten composites (Wf/W) — •L. Raumann1,2, J.W. Coenen1, J. Riesch3, Y. Mao1,2, D. Schwalenberg1,2, H. Gietl3, T. Höschen3, Ch. Linsmeier1, and O. Guillon1,21Institut für Energie und Klimaforschung, Forschungszentrum Jülich GmbH, 52425 Jülich — 2Rheinisch-Westfälische Technische Hochschule Aachen, 52062 Aachen — 3Max-Planck-Institut für Plasmaphysik, 85748 Garching b. München

Due to many excellent material properties, tungsten is currently the main candidate for the first wall material in future fusion devices. However, its intrinsic brittleness and its susceptibility to operational embrittlement are still a major concern. To overcome this drawback, Wf/W composites featuring pseudo-ductility are developed. Bulk material can be successfully produced by coating tungsten fabrics via CVD. However, a fully dense composite with a high fiber volume fraction (30-40%) is still a challenge. Therefore, a Comsol model is developed including the complex coupling of transport phenomena, chemical reaction kinetics and solid domain growth. The model was successfully validated experimentally for the deposition on single tungsten fibers in heated tubes varying the temperature, partial pressures and gas flow. Currently, the model is validated against the infiltration of tungsten fabrics with varying fiber distances. As next step the process parameters and the fabric geometry will be optimized within the model to acquire the recipe for a fully dense Wf/W composite with a sufficient high fiber volume fraction.

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