Ultrasonic Investigation of Thin Ceramic Plates by Means of Delay Line Contact Mode

The aim of this work is to investigate plates of Peltier modules by means of an ultrasonic method. A pulse-echo contact method was applied for precise measurement of thickness. Transducers with delay lines, emitting at 5 MHz, 10 MHz, 15 MHz and 20 MHz, were used to determine the operating frequency range. An analysis of a number of echoes, amplitude and shape of signals, pulse duration and pulse rise time was performed. Ceramic plates of six Peltier modules, models TEC1-12708 and TEC1-12710, were measured with a selected transducer of 15 MHz. Thicknesses at 25 points of each plate were determined. Variation of the obtained values is observed. Comparative analysis of the results for all measured plates can be used for quality evaluation of the modules.