Effects of pre-cracking on small punch creep testing of a vacuum plasma-sprayed CoNiCrAlY coating

Chen, H.; Hyde, T.H.; Voisey, K.T.; McCartney, D.G.

Abstract

This paper presents the results of small punch creep testing (SPCT) of a vacuum plasma-sprayed (VPS) CoNiCrAlY coating (Co – 31.7%, Ni – 20.8%, Cr – 8.1%, Al – 0.5%, Y, all in wt%) carried out at 750 grad. C. Coating cross-sections, after initial heat treatment, after sample clamping in the test rig prior to testing and after SPCT, were examined using scanning electron microscopy (SEM). A dual phase structure consisting of fcc gamma-Ni matrix and a bcc beta-NiAl secondary phase was found to exist. A large number of partially melted powder particles, with a semi-continuous beta layer surrounding most of the partially melted particles, were found in the coating. Pre-cracking was observed to occur around the partially melted particles after sample clamping was applied in the test rig prior to testing. This was due to the inherent brittleness of the beta layer around those particles. Very short failure times were obtained from the SPCT of the specific VPS CoNiCrAlY coatings, due to the pre-existing cracks formed during sample clamping.

Citation

Chen, H., Hyde, T., Voisey, K., & McCartney, D. (2018). Effects of pre-cracking on small punch creep testing of a vacuum plasma-sprayed CoNiCrAlY coating. Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications, 232(3), 242-249. doi:10.1177/1464420715622495

• Journal Article Type: Article
• Acceptance Date: Nov 23, 2015
• Online Publication Date: Jan 5, 2016
• Publication Date: Mar 1, 2018
• Deposit Date: Jan 23, 2019
• Journal: Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
• Print ISSN: 1464-4207
• Electronic ISSN: 2041-3076
• Publisher: SAGE Publications (UK and US)
• Peer Reviewed: Peer Reviewed
• Volume: 232
• Issue: 3
• Pages: 242-249
• DOI: https://doi.org/10.1177/1464420715622495
• Public URL: https://nottingham-repository.worktribe.com/output/1491245
• Publisher URL: https://journals.sagepub.com/doi/10.1177/1464420715622495