This title appears in the Scientific Report :
2021
Please use the identifier:
http://hdl.handle.net/2128/28479 in citations.
Please use the identifier: http://dx.doi.org/10.3390/met11071089 in citations.
Improving the W Coating Uniformity by a COMSOL Model-Based CVD Parameter Study for Denser Wf/W Composites
Improving the W Coating Uniformity by a COMSOL Model-Based CVD Parameter Study for Denser Wf/W Composites
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 embr...
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Personal Name(s): | Raumann, Leonard (Corresponding author) |
---|---|
Coenen, Jan Willem / Riesch, Johann / Mao, Yiran / Schwalenberg, Daniel / Gietl, Hanns / Linsmeier, Christian / Guillon, Olivier | |
Contributing Institute: |
Plasmaphysik; IEK-4 |
Published in: | Metals, 11 (2021) 7, S. 1089 - |
Imprint: |
Basel
MDPI
2021
|
DOI: |
10.3390/met11071089 |
Document Type: |
Journal Article |
Research Program: |
Implementation of activities described in the Roadmap to Fusion during Horizon 2020 through a Joint programme of the members of the EUROfusion consortium Power-based Fuels and Chemicals |
Link: |
OpenAccess |
Publikationsportal JuSER |
Please use the identifier: http://dx.doi.org/10.3390/met11071089 in citations.
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. |