Infrared Thermal Wave Studies of Coated Surfaces

Abstract

In this paper we discuss the recent results of our infrared thermal wave studies of plasma-sprayed coatings, coatings on automotive metal panels, and metal to polymer adhesive joints. The purpose of this study is to develop a reliable NDE technique to assess the quality and test the integrity of these coatings and bonding. The experimental method is a pulsed heating and synchronous infrared thermal wave detection technique commonly referred to as box-car thermal wave video imaging. [1–3] The thermal wave propagation times for plasma-sprayed coatings and adhesive bonds are usually long enough for many NDE applications that the method used here can be considered to be a real time technique. In the IR thermal wave imaging method (Fig. 1) the sample surface is pulse-heated by a bank of flash lamps, and the thermal response of the surface is monitored as a function of time and space by means of an infrared video camera. The resulting video signal is sent to a fast signal processing system and averaged synchronously on a pixel-by-pixel basis. The final data are displayed in the form of 2-dimensional or 3-dimensional gray scale or pseudocolor images of subsurface thermal features.KeywordsThermal WaveFlash LampThermal Barrier CoatPiston HeadPaint PanelThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.