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Title: Surface morphology of Tungsten-F82H after high-heat flux testing using plasma-arc lamps

F82H reduced activation steel coated with vacuum plasma sprayed (VPS) tungsten is a candidate as a plasma facing material for main chamber components in future fusion reactors. Due to different coefficients of thermal expansion (CTE), significant thermal stresses are expected in these bimetallic materials. Thus, a major uncertainty in the performance of W/F82H components during the operation under high-heat fluxes is the effect of CTE mismatch. Here in this study, a high intensity plasma-arc lamp was used for high-heat flux cycling tests of W/F82H specimens. While no surface damage was observed for specimens tested for 100–200 cycles at a heat flux of 1.4 MW/m 2 pulse when the backside surface temperature was maintained below 550 °C, significant cracking occurred at higher temperatures. A simple analytical model for bimetallic materials indicated that the stress in the VPS-W layer is likely to exceed its failure stress solely due to the bilayer thermal stress. Finally, a finite element analysis of the state of stress and deformation confirmed that a significant stress also would occur at the W surface due to the rigid-body like constraint imposed by the clamp, which can be the main cause of the cracking.
Authors:
 [1] ; ORCiD logo [2] ;  [3] ;  [4] ;  [2] ;  [2] ; ORCiD logo [2] ;  [1]
  1. Osaka Univ. (Japan). Graduate School of Engineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Kyushu Univ. (Japan). RIAM
  4. Osaka Prefectural Univ., Sakai, Osaka (Japan). Radiation Research Center
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Published Article
Journal Name:
Nuclear Materials and Energy
Additional Journal Information:
Journal Volume: 16; Journal Issue: C; Journal ID: ISSN 2352-1791
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; High-heat flux testing; Thermal stress; Bimetallic; Tungsten; Reduced activation steel
OSTI Identifier:
1458574
Alternate Identifier(s):
OSTI ID: 1460222

Ibano, Kenzo S., Sabau, Adrian S., Tokunaga, Kazutoshi, Akiyoshi, Masafumi, Kiggans Jr, James O., Schaich, Charles Ross, Katoh, Yutai, and Ueda, Yoshio. Surface morphology of Tungsten-F82H after high-heat flux testing using plasma-arc lamps. United States: N. p., Web. doi:10.1016/j.nme.2018.06.015.
Ibano, Kenzo S., Sabau, Adrian S., Tokunaga, Kazutoshi, Akiyoshi, Masafumi, Kiggans Jr, James O., Schaich, Charles Ross, Katoh, Yutai, & Ueda, Yoshio. Surface morphology of Tungsten-F82H after high-heat flux testing using plasma-arc lamps. United States. doi:10.1016/j.nme.2018.06.015.
Ibano, Kenzo S., Sabau, Adrian S., Tokunaga, Kazutoshi, Akiyoshi, Masafumi, Kiggans Jr, James O., Schaich, Charles Ross, Katoh, Yutai, and Ueda, Yoshio. 2018. "Surface morphology of Tungsten-F82H after high-heat flux testing using plasma-arc lamps". United States. doi:10.1016/j.nme.2018.06.015.
@article{osti_1458574,
title = {Surface morphology of Tungsten-F82H after high-heat flux testing using plasma-arc lamps},
author = {Ibano, Kenzo S. and Sabau, Adrian S. and Tokunaga, Kazutoshi and Akiyoshi, Masafumi and Kiggans Jr, James O. and Schaich, Charles Ross and Katoh, Yutai and Ueda, Yoshio},
abstractNote = {F82H reduced activation steel coated with vacuum plasma sprayed (VPS) tungsten is a candidate as a plasma facing material for main chamber components in future fusion reactors. Due to different coefficients of thermal expansion (CTE), significant thermal stresses are expected in these bimetallic materials. Thus, a major uncertainty in the performance of W/F82H components during the operation under high-heat fluxes is the effect of CTE mismatch. Here in this study, a high intensity plasma-arc lamp was used for high-heat flux cycling tests of W/F82H specimens. While no surface damage was observed for specimens tested for 100–200 cycles at a heat flux of 1.4 MW/m2 pulse when the backside surface temperature was maintained below 550 °C, significant cracking occurred at higher temperatures. A simple analytical model for bimetallic materials indicated that the stress in the VPS-W layer is likely to exceed its failure stress solely due to the bilayer thermal stress. Finally, a finite element analysis of the state of stress and deformation confirmed that a significant stress also would occur at the W surface due to the rigid-body like constraint imposed by the clamp, which can be the main cause of the cracking.},
doi = {10.1016/j.nme.2018.06.015},
journal = {Nuclear Materials and Energy},
number = C,
volume = 16,
place = {United States},
year = {2018},
month = {6}
}