Damage Characterization of Thermal Barrier Coatings by Acoustic Emission and Thermography

• Published in: Advanced engineering materials Vol. 14; no. 9; pp. 790 - 794
• Main Authors: Nies, Daniel, Rehmer, Birgit, Skrotzki, Birgit, Vaßen, Robert
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.09.2012; WILEY‐VCH Verlag
• ISSN: 1438-1656; 1527-2648
• DOI: 10.1002/adem.201200107

Thermal barrier coatings allow increasing the operating temperature and efficiency of land‐, sea‐, or air‐based turbines. As failure of the coating may result in serious damage of the turbine, reliable estimation of its lifetime is essential. To assess the lifetime, cyclic tests are conceived to combine thermal loading by heating the surface of the coating with laser irradiation and nondestructive methods for damage determination. Using laser irradiation allows a high reproducibility of the thermal load. The temperature of the sample surface during thermal loading is determined by an infrared‐camera which also enables the possibility to detect damage in the coating via thermography. Additionally, four acoustic sensors, attached to the experimental setup, are used to detect damage in the sample and determine the source of acoustic events. Results of acoustic emission correlate well with thermographic images that visualize the formation and evolution of damage through delaminations in the samples. Thermal fatigue tests of thermal barrier coatings (TBCs) by heating the surface with laser irradiation were complemented by nondestructive methods. A comparison is made between results of acoustic emission and thermographic images in order to visualize the formation and evolution of damage through delamination in the samples.