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The nondestructive measurement of strain distributions in air plasma sprayed thermal barrier coatings as a function of depth from entire Debye–Scherrer rings
Author(s) -
Li Chun,
Xiao Ping,
Cernik Robert
Publication year - 2020
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s1600576719016327
Subject(s) - thermal barrier coating , materials science , composite material , coating , residual stress , debye , diffraction , synchrotron , optics , crystallography , condensed matter physics , chemistry , physics
The residual strain distribution has been measured as a function of depth in both top coat and bond coat in as‐received and heat‐treated air plasma sprayed thermal barrier coating samples. High‐energy synchrotron X‐ray beams were used in transmission to produce full Debye–Scherrer rings whose non‐circular aspect ratio gave the in‐plane and out‐of‐plane strains far more efficiently than the sin 2 ψ method. The residual strain in the bond coat is found to be tensile and the strain in the β phase of the as‐received sample was measured. The residual strains observed in the top coat were generally compressive (increasing towards the interface), with two kinds of nonlinear trend. These was a `jump' feature near the interface, and in some cases there was another `jump' feature near the surface. It is shown how these trend differences can be correlated to cracks in the coating.