Defect detection in multilayered, plasma-sprayed zirconia by time-resolved infrared radiometry: a comparison between analytical and experimental methods

P. Greig Happoldt; William A. Ellingson; Thomas P. Gardiner; John A. Krueger

doi:10.1117/12.171184

21 March 1994 Defect detection in multilayered, plasma-sprayed zirconia by time-resolved infrared radiometry: a comparison between analytical and experimental methods

P. Greig Happoldt, William A. Ellingson, Thomas P. Gardiner, John A. Krueger

Author Affiliations +

Proceedings Volume 2245, Thermosense XVI: An International Conference on Thermal Sensing and Imaging Diagnostic Applications; (1994) https://doi.org/10.1117/12.171184
Event: SPIE's International Symposium on Optical Engineering and Photonics in Aerospace Sensing, 1994, Orlando, FL, United States

Abstract

Analytical and experimental methods were used to study a series of test specimens consisting of plasma sprayed layers of NiCrA1Y I Zr02ofvarious compositions. The coatings were seeded with artificial defects and were sprayed on steel disks. Two types of defects were used: flat bottomed holes drilled in the steel substrate and patches of room temperature vulcanizing silicone within the coatings. Defect sizes ranged from 0. 1 to 10 mm and were at depths below the coating surface from 0.6 to 3.6 mm. The method of time resolved infrared radiometry was used with two different heat sources, an acetylene torch and a high intensity lamp, to inspect the coatings. The torch allowed excellent sensitivity at depths of less than 2 mm and the lamp revealed flaws through the full coating thickness. Two analytical models were developed to study heat flow in the test specimens: a finite element model and an electrical analog model. Results from the two models were compared to check consistency and the finite element model results were compared with experimental results. The finite element code was chosen for further development due to its greater flexibility and ease of use. This paper was presented at the Thermosense XV conference.

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P. Greig Happoldt, William A. Ellingson, Thomas P. Gardiner, and John A. Krueger "Defect detection in multilayered, plasma-sprayed zirconia by time-resolved infrared radiometry: a comparison between analytical and experimental methods", Proc. SPIE 2245, Thermosense XVI: An International Conference on Thermal Sensing and Imaging Diagnostic Applications, (21 March 1994); https://doi.org/10.1117/12.171184

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