Thermal Wave Imaging for Materials Characterization

Abstract

Novel techniques for materials characterization and nondestructive evaluation are being continually developed to meet the requirements of examining an ever-increasing range of new materials, A wide range of physical properties and processes are exploited in the current measurement technologies and it is often necessary to match the characterization technique to the materials problem at hand. A very recent addition to the repertoire of materials characterization techniques is thermal wave imaging. This field encompasses a wide range of techniques for exciting and detecting periodic temperature fields or “thermal waves” in solids. The physical probe for this materials characterization technique is heat and thermal wave imaging thus provides information about local variations in sample thermal properties such as the thermal conductivity and the heat capacity. Thermal wave imaging is a developing technique and although the contrast mechanisms can be identified in simple situations, understanding the contrast in thermal wave images for complicated sample geometries and detection schemes is very involved (1). It is readily apparent that many topics of interest in materials science lend themselves well to characterization on the basis of variations in the sample’s thermal properties. The examples considered in this paper consider interfaces and show that the measurement of variations in the interruption of heat flow across these interfaces provides an effective means for characterizing the structure of the interface.