Effect of APS flash bond coatings on furnace cycle lifetime of disks and rods

Conference · Sat Jun 01 00:00:00 EDT 2019

DOI:https://doi.org/10.1115/GT2019-90501· OSTI ID:1546537

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

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1. ORNL
2. Stony Brook University (SUNY)

Air plasma sprayed (APS) flash coatings on high velocity oxygen fuel (HVOF) bond coatings are well known to extend the lifetime of thermal barrier coatings. Recent work compared flash coatings of NiCoCrAlY and NiCoCrAlYHfSi applied to both rods and disk substrates of alloy 247. For rod specimens, 100-h cycles were used at 1100°C in wet air. Both flash coatings significantly improved the lifetime compared to HVOF-only and VPS-only MCrAlY bond coatings with no statistical difference between the two flash coatings. For disk specimens tested in 1-h cycles at 1100°C in wet air, the NiCoCrAlY flash coating significantly outperformed an HVOFonly NiCoCrAlYHfSi bond coating and a NiCoCrAlYHfSi flash coating. The flash coatings formed a mixed oxide-metal zone that appeared to inhibit crack formation and extend lifetime. In addition to the flash coating increasing the bond coating roughness, the underlying HVOF layer acted as a source of Al for this intermixed zone and prevented the oxide from penetrating deeper into the bond coating. The lower Y+Hf level in the Y-only flash coating appeared to minimize oxidation in the flash layer, thereby increasing the benefit compared to a NiCoCrAlYHfSi flash coating.

• 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: 1546537
• Resource Relation: Conference: ASME Turbo Expo 2019 - Phoenix, Arizona, United States of America - 6/17/2019 8:00:00 AM-6/21/2019 8:00:00 AM
• Country of Publication: United States
• Language: English