Effect of Atmosphere Composition on Lifetime and Oxidation Behavior of EB-PVD TBC with NiPtAl Bondcoats

Abstract:

NiPtAl coatings are widely used as bondcoats for thermal barrier coating (TBC) systems during high temperature exposure. Pt modified aluminide coatings on the CMSX-4 Ni-base alloy were oxidized at 1150°C in different atmospheres. Cross-section oxide layer morphologies on the NiPtAl coatings after TBC failure were similar in air with that in air+15%H₂O. The surface morphologies of as-received low and high-Pt bondcoats showed great effect on the oxide layer growth and morphologies due to the different compositions within the two bondcoats. The irregular alumina surface on the low-Pt bondcoat was showed due to the slipping of the NiPtAl grains. Raman spectroscopy illustrated that the alumina mainly consisted θ and α-Al₂O₃ during the Ar+20%O₂ exposure, however, only α-Al₂O₃ could be found in Ar+4%H₂+2%H₂O during short time exposure. Low oxygen partial pressure of Ar+4%H₂+2%H₂O perhaps is the reason that spinel and θ-Al₂O₃ can not formed, and directly promotes the α-Al₂O₃ formation.

• Periodical: Advanced Materials Research (Volumes 652-654)
• Pages: 1822-1825
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.652-654.1822
• Online since: January 2013
• Authors: Peng Song, Jian Sheng Lu
• Keywords: Lifetime, Niptal Coating, Oxidation, Water Vapor

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