Journal of Materials Engineering

, Volume 9, Issue 1, pp 71–79 | Cite as

Optothermal NDE of thermal-barrier coatings

  • P. Cielo
  • S. Dallaire


An optothermal technique is described for the nondestructive evaluation of thermal barriers, such as ceramic plasma-sprayed coatings. This method is noncontact and requires access from one side only of the sample, thereby making it easier to inspect awkwardly shaped or difficult-to-reach pieces. A laser beam irradiates the coated material, raising its surface temperature to some degrees above ambient. The surface temperature is monitored during or after irradiation by an infrared detector to obtain a characteristic temperature-time curve (thermogram). After appropriate processing, the thermogram provides information on the thermal properties of the coating if its thickness is known. Alternatively, the thickness of the coating can be estimated if its thermal properties are known. In either case, the optothermal analysis allows one to evaluate the degree of thermal insulation provided by the coating. Each measurement is performed nondestructively and within a time period of less than 0.5 sec per point using the single-shot method.


Coating Thickness Thermal Effusivity Heated Area ZrO2 Coating Optical Penetration Depth 
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Copyright information

© Springer-Verlag New York Inc. 1987

Authors and Affiliations

  • P. Cielo
    • 1
  • S. Dallaire
    • 1
  1. 1.Industrial Materials Research InstituteNational Research Council CanadaBouchervilleCanada

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