Transient thermal wave techniques for the evaluation of surface coatings

A thermal wave interference model is developed to analyse the response of coating to pulsed and stepped heating. The influence of the relative thermal properties of coating and substrate and the possibility of coating translucency are included in the analysis. The potential of transient techniques for the measurement of coating thickness is demonstrated and compared with the continuous wave technique. Experimental results obtained from plasma sprayed zirconia coatings are presented and compared with theoretical predictions.