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@ARTICLE{Raumann:894452,
author = {Raumann, Leonard and Coenen, Jan Willem and Riesch, Johann
and Mao, Yiran and Schwalenberg, Daniel and Gietl, Hanns and
Linsmeier, Christian and Guillon, Olivier},
title = {{I}mproving the {W} {C}oating {U}niformity by a {COMSOL}
{M}odel-{B}ased {CVD} {P}arameter {S}tudy for {D}enser
{W}f/{W} {C}omposites},
journal = {Metals},
volume = {11},
number = {7},
issn = {2075-4701},
address = {Basel},
publisher = {MDPI},
reportid = {FZJ-2021-03231},
pages = {1089 -},
year = {2021},
abstract = {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.},
cin = {IEK-4},
ddc = {530},
cid = {I:(DE-Juel1)IEK-4-20101013},
pnm = {1232 - Power-based Fuels and Chemicals (POF4-123) /
EUROfusion - Implementation of activities described in the
Roadmap to Fusion during Horizon 2020 through a Joint
programme of the members of the EUROfusion consortium
(633053)},
pid = {G:(DE-HGF)POF4-1232 / G:(EU-Grant)633053},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000676817800001},
doi = {10.3390/met11071089},
url = {https://juser.fz-juelich.de/record/894452},
}