TY - JOUR
T1 - Phase evolution upon aging of air plasma sprayed t′-zirconia coatings
T2 - II-microstructure evolution
AU - Krogstad, Jessica A.
AU - Leckie, Rafael M.
AU - Krämer, Stephan
AU - Cairney, Julie M.
AU - Lipkin, Don M.
AU - Johnson, Curtis A.
AU - Levi, Carlos G.
N1 - Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013/1
Y1 - 2013/1
N2 - The correlation between microstructural and phase evolution in aged, yttria-partially-stabilized zirconia, air plasma-sprayed coatings is discussed. Freestanding coatings with the dense, vertically cracked structure were isothermally aged at 1482°C (2700°F) in air. Characterization of the resulting microstructures was conducted using transmission electron microscopy, then compared with a parallel analysis of the phase evolution via synchrotron X-ray diffraction (XRD) described in Part I. Additional context was provided by related studies on vapor-deposited coatings. Several salient points can be extracted from these assessments. XRD was further validated as a practical method for studying phase stability after clarification of how the possible phases are defined, including the following: (i) the nature of the t′ phase observed in XRD after phase decomposition has begun and (ii) the relationship between the Y-rich tetragonal (t″) and Y-rich cubic (c) phases reported to coexist via XRD. A strong relationship between the initial microstructure and the subsequent phase destabilization is also reported. As a result, phase evolution is proposed to proceed via two competing routes. The interplay between these mechanisms dictates the incubation time for monoclinic formation within a given coating.
AB - The correlation between microstructural and phase evolution in aged, yttria-partially-stabilized zirconia, air plasma-sprayed coatings is discussed. Freestanding coatings with the dense, vertically cracked structure were isothermally aged at 1482°C (2700°F) in air. Characterization of the resulting microstructures was conducted using transmission electron microscopy, then compared with a parallel analysis of the phase evolution via synchrotron X-ray diffraction (XRD) described in Part I. Additional context was provided by related studies on vapor-deposited coatings. Several salient points can be extracted from these assessments. XRD was further validated as a practical method for studying phase stability after clarification of how the possible phases are defined, including the following: (i) the nature of the t′ phase observed in XRD after phase decomposition has begun and (ii) the relationship between the Y-rich tetragonal (t″) and Y-rich cubic (c) phases reported to coexist via XRD. A strong relationship between the initial microstructure and the subsequent phase destabilization is also reported. As a result, phase evolution is proposed to proceed via two competing routes. The interplay between these mechanisms dictates the incubation time for monoclinic formation within a given coating.
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U2 - 10.1111/j.1551-2916.2012.05460.x
DO - 10.1111/j.1551-2916.2012.05460.x
M3 - Article
AN - SCOPUS:84872105797
SN - 0002-7820
VL - 96
SP - 299
EP - 307
JO - Journal of the American Ceramic Society
JF - Journal of the American Ceramic Society
IS - 1
ER -