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Evaluation of Oxidation Damage in Thermal Barrier Coating SystemsA method based on the technique of dilatometry has been established to quantitatively evaluate the interfacial damage due to the oxidation in a thermal barrier coating system. Strain isolation and adhesion coefficients have been proposed to characterize the thermal barrier coating (TBC) performance based on its thermal expansion behavior. It has been found that, for a thermal barrier coating system consisting of ZrO2-8%Y2O3/FeCrAlY/4140 steel substrate, the oxidation of the bond coat and substrate significantly reduced the ceramic coating adherence, as inferred from the dilatometry measurements. The in-situ thermal expansion measurements under 30 deg C to 700 deg C thermal cycling in air showed that the adhesion coefficient, A(sub i) decreased by 25% during the first 35 oxidation cycles. Metallography showed that delamination occurred at both the ceramic/bond coat and bond coat/substrate interfaces. In addition, the strain isolation effect has been improved by increasing the FeCrAlY bond coat thickness. The strain isolation coefficient, Si, increased from about 0.04 to 0.25, as the bond coat thickness changed from 0.1 mm to 1.0 mm. It may be possible to design optimum values of strain isolation and interface adhesion coefficients to achieve the best TBC performance.
Document ID
19970021978
Document Type
Conference Paper
Authors
Zhu, Dongming (NASA Lewis Research Center Cleveland, OH United States)
Miller, Robert A. (NASA Lewis Research Center Cleveland, OH United States)
Date Acquired
September 6, 2013
Publication Date
November 1, 1996
Subject Category
Nonmetallic Materials
Report/Patent Number
NASA-TM-107360
NAS1.15:107360
ARL-XA-TR-1254
AD-A320578
NASA-E-10518
Funding Number(s)
PROJECT: DA Proj. 1L1-61102-AH-45
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
THERMAL PROPERTIES
BARRIER COATINGS

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