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Characterization of the Benefit of APS Flash Coatings in Improving TBC Lifetime

  • Bruce A. Pint
  • , Michael J. Lance
  • , Ercan Cakmak
  • , Kenneth A. Kane
  • , J. Allen Haynes
  • , Edward J. Gildersleeve
  • , Sanjay Sampath

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

3 Scopus citations

Abstract

The addition of an air plasma sprayed (APS) “flash” layer on top of a high velocity oxygen fuel (HVOF) bond coating has been shown to extend the lifetime of thermal barrier coatings. A series of furnace cycle tests (FCTs) has been conducted at 1100 °C in air + 10% H2O to study the benefit of flash coatings on rod and disk alloy 247 specimens and provide a better mechanistic understanding of their benefit. Flash coatings of NiCoCrAlY and NiCoCrAlYHfSi both improved the FCT lifetime of rod specimens tested in 100-h cycles and disk specimens tested in 1-h cycles. In 1-h cycles, the NiCoCrAlY flash coating significantly outperformed an HVOF-only NiCoCrAlYHfSi bond coating and a NiCoCrAlYHfSi flash coating. Both flash coatings increased the bond coating roughness compared to HVOF. During exposure, the flash layer formed an intermixed alumina-metal layer that appeared to inhibit crack formation. Using a time series of observations, the lower Y + Hf content in the Y-only flash coating appeared to reduce Al consumption. The HVOF layer acted as a source of Al for the adjacent mixed zone. A second series of specimens included a fully APS bond coating where oxide had penetrated through the entire coating to the substrate after only 100, 1-h cycles and lifetime was similar to an HVOF-only bond coating. The inner HVOF layer with the outer APS flash coating prevented this complete penetration from occurring.

Original languageEnglish
Title of host publicationSuperalloys 2020 - Proceedings of the 14th International Symposium on Superalloys
EditorsSammy Tin, Mark Hardy, Justin Clews, Jonathan Cormier, Qiang Feng, John Marcin, Chris O'Brien, Akane Suzuki
PublisherSpringer Science and Business Media Deutschland GmbH
Pages739-746
Number of pages8
ISBN (Print)9783030518332
DOIs
StatePublished - 2020
Event14th International Symposium on Superalloys, Superalloys 2021 - Seven Springs, United States
Duration: Sep 12 2021Sep 16 2021

Publication series

NameMinerals, Metals and Materials Series

Conference

Conference14th International Symposium on Superalloys, Superalloys 2021
Country/TerritoryUnited States
CitySeven Springs
Period09/12/2109/16/21

Keywords

  • APS flash coating
  • Furnace cycle testing
  • Thermal barrier coatings

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