High temperature immersion ultrasonic probes

Ultrasonic probes without delay line, in order to improve SNR thermal shock resistance were developed. New immersion probe was composed by PZT/PZT sol-gel composite film onto thin metal plate with protection case. High temperature durability was achieved because sol-gel composite film had good acoustic coupling without couplant, had reasonable broadband characteristic without backing material, and the sol-gel composite film itself had high thermal shock resistance due to porosity in the film. That immersion probe could operate even at 200°C in silicone oil bath. Further it was possible to receive second reflected echoes from top and bottom surface of a 36 mm thick aluminum and it indicated that this probe showed possibility of non-destructive testing such as crack detection.