TY - JOUR
T1 - Effects of pre-cracking on small punch creep testing of a vacuum plasma-sprayed CoNiCrAlY coating
AU - Chen, H.
AU - Hyde, T. H.
AU - Voisey, K. T.
AU - McCartney, D. G.
N1 - Publisher Copyright:
© 2016, © IMechE 2016.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2018/3/1
Y1 - 2018/3/1
N2 - 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 ℃. 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 a fcc γ-Ni matrix and a bcc β-NiAl secondary phase was found to exist. A large number of partially melted powder particles, with a semi-continuous β 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 β 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.
AB - 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 ℃. 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 a fcc γ-Ni matrix and a bcc β-NiAl secondary phase was found to exist. A large number of partially melted powder particles, with a semi-continuous β 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 β 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.
KW - creep
KW - failure
KW - pre-cracking
KW - Small punch creep test
KW - VPS coating
UR - http://www.scopus.com/inward/record.url?scp=85041700547&partnerID=8YFLogxK
U2 - 10.1177/1464420715622495
DO - 10.1177/1464420715622495
M3 - Article
AN - SCOPUS:85041700547
SN - 1464-4207
VL - 232
SP - 242
EP - 249
JO - Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
JF - Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications
IS - 3
ER -