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

Conference · Tue Sep 01 00:00:00 EDT 2020 · The Minerals, Metals & Materials Series

DOI:https://doi.org/10.1007/978-3-030-51834-9_71· OSTI ID:1657978

Pint, Bruce  ^[1]; Lance, Michael J.  ^[1]; Cakmak, Ercan  ^[1]; Kane, Kenneth ^[1]; Haynes, James A.  ^[1]; Gildersleeve, Ed ^[2]; Sampath, S ^[2]

---

1. ORNL
2. Stony Brook University (SUNY)

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.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Fossil Energy (FE)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1657978
• Journal Information: The Minerals, Metals & Materials Series, Conference: International Symposium on Superalloys 2020, Seven Springs, Pennsylvania, USA, 9/13/2020 - 9/17/2020; ISSN 2367-1181
• Country of Publication: United States
• Language: English