Insights on the high-temperature operational limits of ZrO2-Y2O3 TBCs manufactured via air plasma spray

From National Research Council Canada

DOIResolve DOI: https://doi.org/10.1007/s11665-017-2562-5
AuthorSearch for: 1; Search for: 1
Name affiliation
  1. National Research Council of Canada. Automotive and Surface Transportation
FormatText, Article
Journal titleJournal of Materials Engineering and Performance
ISSN1059-9495
1544-1024
Volume26
Issue3
Pages1272–1282
Subjectaerospace; air plasma spray (APS); life prediction; thermal barrier coating (TBC); thermal conductivity; thermal gradient cyclic testing; ZrO2-7-8 wt.%Y2O3 (YSZ)
Abstract
The effective high-temperature operation limit of a ZrO2-7-8 wt.%Y2O3 (YSZ) thermal barrier coating (TBC) manufactured via air plasma spray (APS) is considered to be ~1300 °C. This is related to the metastable tetragonal t′-phase formed during the rapid quenching of the YSZ particles during spraying. The t′-phase transforms into the equilibrium tetragonal and cubic phases at temperatures ≥~1300 °C, which can lead to the formation of the monoclinic phase of YSZ upon cooling to room temperature. This formation of the monoclinic phase is accompanied by a volume expansion that leads to TBC failure due to extensive micro-cracking. To further investigate this limitation, an APS YSZ TBC was sprayed on a CMSX-4 substrate. By using a thermal (laser) gradient cyclic testing, a temperature gradient was generated across the TBC/substrate system. The YSZ T-front and substrate backside T-back temperature levels were ~1500 and ~1000 °C, respectively. In cycle conditions (5-min or 1-h hot and 2-min cool), no TBC failure has been observed. This behavior was partially attributed to the unexpected absence of the monoclinic phase of the YSZ in the cycled coatings. Although preliminary, these results are promising regarding increasing the effective high-temperature operational limits of APS YSZ TBCs.
Publication date
PublisherSpringer
LanguageEnglish
Peer reviewedYes
NPARC number23003118
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Record identifier83262453-3b34-47f9-a832-cff0562eb832
Record created2018-04-20
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