Novel, High Temperature, Low Frequency, Thin Film, NDT Ultrasound Transducers

Ultrasonic flaw detection is a valuable NDT tool, allowing for safe, reliable, quantitative measurements, for applications such as pipe wall thickness monitoring. However, most ultrasonic tools are relatively expensive, inflexible, and cannot operate at temperatures above 200 degrees C without considerable loss of signal, or even device destruction. Sputtered thin film piezoelectrics are flexible, affordable and can function to very high temperatures (theoretically >1500 degrees C), however they are intrinsically too high frequency (in the 100's MHz) for most NDT inspections (typically <20 MHz), and suffer from low signal to noise ratios (SNR). This work demonstrates a new, affordable, thin film sensor created at Novosound for low frequency, high temperature NDT applications. It can perform as low as 5 MHz, and has so far shown a sustained and reliable performance at 350 degrees C, with a high (22 dB) SNR. This technology has the potential to function >1300 degrees C.