Ultrasonic transducers based on spray coated PZT film for in situ operation for temperatures up to 200 °C

Ultrasonic testing is widely used for assessing the integrity of structures, and increasingly, there is much interest in the inspection of components operating at elevated temperatures. Degeneration of acoustic couplant and active element are among the challenges widely reported to develop ultrasonic piezoelectric transducers operating at higher temperatures. In our study, the development of an in situ ultrasonic transducer using spray deposited PZT slurry as the active element to perform bulk ultrasonic inspection/monitoring of components and structures operating at elevated temperatures (up to 200° C) is described. This method allows deposition of PZT coatings of thickness > 500 µm. The operation of the developed ultrasonic transducer performing pulse-echo ultrasonic measurements at 1 MHz up to 200 °C is demonstrated experimentally and compared with conventional methods. Merits and limitations to practical realisation are also discussed.