Thermal conductivity, phase stability, and oxidation resistance of Y 3Al5O12 (YAG)/Y2O 3-ZrO2 (YSZ) thermal-barrier coatings

Y. J. Su, R. W. Trice, K. T. Faber, H. Wang, W. D. Porter

Research output: Contribution to journalArticlepeer-review

91 Scopus citations

Abstract

This paper describes a new multilayer TBC that incorporates a 10 μm-thick oxygen barrier layer of yttrium-aluminum garnet (YAG) into a typical YSZ TBC system. The thermal conductivity of as-sprayed YAG/YSZ coatings was reduced due to excessive porosity and amorphous areas in the YAG layer. After long-term heat treatments, the conductivity of the multilayer was unaffected by the presence of YAG. Sintering and recrystallization of the amorphous YAG regions occurred during high-temperature heat treatments. While YAG itself possesses excellent phase stability, its presence also improved the phase stability of zirconia near the YAG/YSZ interface, inhibiting the outward diffusion of yttrium from high-yttria t-ZrO2 The YAG layer reduced the NiCoCrAlY bond-coat oxidation rate by a factor of three during isother-malfurnace tests conducted at 1200°C.

Original languageEnglish
Pages (from-to)253-271
Number of pages19
JournalOxidation of Metals
Volume61
Issue number3-4
DOIs
StatePublished - Apr 2004

Funding

Funding was provided by the U.S. Department of Energy, Federal Energy Technology Center, Cooperative Agreement No. DE-FC21-92MC 29061, under subcontract 96-01-SR047. The thermal conductivity testing was supported by the U.S. DOE, Assistant Secretary of Transportation Technologies, as part of the HTML User Program under contract DE-AC05-00OR22725, managed by UT-Batelle, LLC. The authors would like to thank Richard Marzec for general assistance in the thermal spray laboratory. Discussions with Dr. Thomas Bernecki were also very useful. The assistance of Dr. Ramesh Subramanian at Siemens-Westinghouse in obtaining superalloy substrates is also appreciated.

Keywords

  • Conductivity
  • Garnet
  • Thermal barrier coating
  • X-ray diffraction
  • Zirconia

Fingerprint

Dive into the research topics of 'Thermal conductivity, phase stability, and oxidation resistance of Y 3Al5O12 (YAG)/Y2O 3-ZrO2 (YSZ) thermal-barrier coatings'. Together they form a unique fingerprint.

Cite this