Infrared thermal wave imaging of thermal barrier coatings for diesel applications

Ceramic thermal barrier coating development has been championed by the aerospace industry because of the potential to improve gas turbine efficiency while reducing metal temperatures. A new technique, developed at Wayne State University, shows considerable promise for such inspections. This paper reports that this technique, called infrared thermal wave imaging, has been instrumental in improving thermal barrier coatings for diesel engine applications. This nondestructive evaluation technique provides rapid inspection of the entire coating surface area, and makes an image of the otherwise hidden defects. The easily interpreted visual information obtained by this technique has been used to modify coating processes and has led to an improved understanding of the localized thermal gradients that occur during the diesel combustion process.