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The Effect of HVOF Bond Coating with APS Flash Coating on TBC Performance

Authors
  • Lance, M. J.1
  • Thiesing, B. P.1
  • Haynes, J. A.1
  • Parish, C. M.1
  • Pint, B. A.1
  • 1 Oak Ridge National Laboratory, Materials Science and Technology Division, 1 Bethel Valley Rd., Oak Ridge, TN, 37831, USA , Oak Ridge (United States)
Type
Published Article
Journal
Oxidation of Metals
Publisher
Springer US
Publication Date
Feb 22, 2019
Volume
91
Issue
5-6
Pages
691–704
Identifiers
DOI: 10.1007/s11085-019-09903-3
Source
Springer Nature
Keywords
License
Yellow

Abstract

To study the benefit of ~ 50-µm-thick air-plasma-sprayed (APS) ‘flash’ bond coatings, NiCoCrAlYHfSi high-velocity oxygen fuel (HVOF) bond coatings were deposited on alloy 247 disk substrates with APS yttria-stabilized zirconia topcoatings. Using 1-h cycles at 1100 °C in air with 10% H2O and HVOF-only bond coatings as a baseline, APS flash coatings extended the average coating lifetime by > 10% using NiCoCrAlYHfSi and > 70% using NiCoCrAlY powder. Coatings were characterized after 0, 100 and 300 cycles and after failure. Residual stress in the thermally grown alumina scale was mapped every 100 cycles using photo-stimulated luminescence piezospectroscopy. The flash coating created an interlocked metal–alumina layer that appeared to inhibit critical crack formation, and the underlying HVOF layer prevented further internal oxidation and appeared to supply the APS flash coating with Al. The addition of Hf and Y to the flash coating increased internal oxidation and accelerated Al consumption, thereby reducing the benefit of the flash coating.

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