Comparison of different models for the determination of the absorption and scattering coefficients of thermal barrier coatings

2014 ◽  
Vol 64 ◽  
pp. 402-410 ◽  
Author(s):  
Li Wang ◽  
Jeffrey I. Eldridge ◽  
S.M. Guo
Keyword(s):  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Scattering Coefficients

Porosity Determination of Thermal Barrier Coatings

1988 ◽  
Author(s):  
Mark Van Roode ◽  
Brad Beardsley
Keyword(s):  
Thermal Conductivity ◽  
Optical Microscopy ◽  
Thermal Barrier Coatings ◽  
Eddy Current ◽  
Water Immersion ◽  
Critical Factor ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Thickness Measurements

Coating porosity is believed to be a critical factor for the thermal conductivity of thermal barrier coatings (TBC’s). A number of different techniques have been used to determine the porosities of thermal barrier coatings for diesel applications as part of a NASA/DOE sponsored study. A comparison is made between methods based on water immersion, optical microscopy, eddy current thickness measurements, and Archimedes principle for TBC porosity determination.

Determination of Thermal Barrier Coatings Average Surface Temperature After Engine Operation for Lifetime Validation

2012 ◽  
Vol 134 (12) ◽  
Author(s):  
Grégoire Witz ◽  
Hans-Peter Bossmann
Keyword(s):  
Surface Temperature ◽  
Thermal Barrier Coating ◽  
Thermal Barrier Coatings ◽  
Operating Conditions ◽  
Thermal Barrier ◽  
Engine Operation ◽  
Barrier Coatings ◽  
Average Surface ◽  
Barrier Coating

Assessment of ex-service parts is important for the power generation industry. It gives us the opportunity to correlate part conditions to specific operating conditions like fuel used, local atmospheric conditions, operating regime, and temperature load. For assessment of thermal barrier coatings, one of the most valuable pieces of information is the local thermal condition. A method has been developed in Alstom, allowing determination of a thermal barrier coating average surface temperature after engine operation. It is based on the analysis of the phase composition of the thermal barrier coating by the acquisition of an X-ray diffraction spectrum of the coating surface, and its analysis using Rietveld refinement. The method has been validated by comparing its outcome to thermal models and base metal temperature mapping data. It is used for assessment of combustor and turbine coatings with various purposes: Determination of remnant coating life, building of lifing models, or determination of the coating degradation mechanisms under some specific operating conditions. Examples will be presented showing applications of this method.

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