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Article

Improving the W Coating Uniformity by a COMSOL Model-Based CVD Parameter Study for Denser Wf/W Composites

1
Forschungszentrum Jülich GmbH (Partner in the Trilateral Euregio Cluster), Institute for Energy and Climate Research, 52428 Jülich, Germany
2
Institute of Mineral Engineering, Rheinisch-Westfälische Technische Hochschule Aachen, 52062 Aachen, Germany
3
Department of Engineering Physics, University of Wisconsin—Madison, Madison, WI 53706, USA
4
Max-Planck-Institute for Plasma Physics, 85748 Bavaria, Germany
5
Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA
6
JARA-Energy, Jülich Aachen Research Alliance, 52428 Jülich, Germany
*
Author to whom correspondence should be addressed.
Academic Editor: Leszek Adam Dobrzanski
Metals 2021, 11(7), 1089; https://doi.org/10.3390/met11071089
Received: 26 May 2021 / Revised: 30 June 2021 / Accepted: 3 July 2021 / Published: 8 July 2021
(This article belongs to the Special Issue Tungsten and Tungsten Alloys)
Tungsten (W) has the unique combination of excellent thermal properties, low sputter yield, low hydrogen retention, and acceptable activation. Therefore, W is presently the main candidate for the first wall and armor material for future fusion devices. However, its intrinsic brittleness and its embrittlement during operation bears the risk of a sudden and catastrophic component failure. As a countermeasure, tungsten fiber-reinforced tungsten (Wf/W) composites exhibiting extrinsic toughening are being developed. A possible Wf/W production route is chemical vapor deposition (CVD) by reducing WF6 with H2 on heated W fabrics. The challenge here is that the growing CVD-W can seal gaseous domains leading to strength reducing pores. In previous work, CVD models for Wf/W synthesis were developed with COMSOL Multiphysics and validated experimentally. In the present article, these models were applied to conduct a parameter study to optimize the coating uniformity, the relative density, the WF6 demand, and the process time. A low temperature and a low total pressure increase the process time, but in return lead to very uniform W layers at the micro and macro scales and thus to an optimized relative density of the Wf/W composite. High H2 and low WF6 gas flow rates lead to a slightly shorter process time and an improved coating uniformity as long as WF6 is not depleted, which can be avoided by applying the presented reactor model. View Full-Text
Keywords: tungsten; fiber composite; chemical vapor deposition; modeling; parameter study tungsten; fiber composite; chemical vapor deposition; modeling; parameter study
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MDPI and ACS Style

Raumann, L.; Coenen, J.W.; Riesch, J.; Mao, Y.; Schwalenberg, D.; Gietl, H.; Linsmeier, C.; Guillon, O. Improving the W Coating Uniformity by a COMSOL Model-Based CVD Parameter Study for Denser Wf/W Composites. Metals 2021, 11, 1089. https://doi.org/10.3390/met11071089

AMA Style

Raumann L, Coenen JW, Riesch J, Mao Y, Schwalenberg D, Gietl H, Linsmeier C, Guillon O. Improving the W Coating Uniformity by a COMSOL Model-Based CVD Parameter Study for Denser Wf/W Composites. Metals. 2021; 11(7):1089. https://doi.org/10.3390/met11071089

Chicago/Turabian Style

Raumann, Leonard, Jan W. Coenen, Johann Riesch, Yiran Mao, Daniel Schwalenberg, Hanns Gietl, Christian Linsmeier, and Olivier Guillon. 2021. "Improving the W Coating Uniformity by a COMSOL Model-Based CVD Parameter Study for Denser Wf/W Composites" Metals 11, no. 7: 1089. https://doi.org/10.3390/met11071089

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