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Presentation RSE 14003962

Advanced characterisation of thermal barrier coatings


CIMTEC2014 13th International Ceramics Congress 9-13 , Giugno-2014.

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F. Cernuschi (RSE SpA)

EVOLRETE 2014 - Evolution and planning of the national electric system

Different thermographic techniques used for microstructural characterizationand the non-destructive testing of thermal barrier coating are presented.

It is known that the thermal diffusivity of plasma sprayed coatings is quite sensitive to the specific microstructure and to operating conditions, namely to the operation atmosphere composition and its pressure. This occurrence makes in principle possible to get information from thermal diffusivity measurements, in a non destructive way, on TBCs microstructure and its evolution as a function of time. The application of this approach to some as sprayed and sintered freestanding atmospheric plasma sprayed YPSZ TBC samples will be outlined. Anisotropy of thermo-physical properties of TBC are significantly affected by the microstructure.

It is therefore worth studying the thermal properties as a function of the specific microstructure along the different directions. A thermographic technique able to estimate in a single experiment both in-plane and in-depth thermal diffusivity of TBC will be presented and compared with the in-plane elastic modulus as measured by the three point bending test. The possibility to estimate the overall porosity content of APS TBC by measuring thermal diffusivity is also discussed. Furthermore an approach for a semi-quantitative estimation of cracks at the interface of APS TBCs from thermal diffusivity values measured by using a single side thermographic technique on coupons subjected to thermal cycling will be presented.

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