High Temperature Performance of 3 MHz 36° Y-Cut Lithium Niobate Ultrasonic Transducer for Non-Destructive Testing at 550 °C

This research presents the development and characterization of a high temperature ultrasound transducer for non-destructive testing (NDT) applications, specifically designed to operate in harsh environments up to 550 °C. The transducer is based on a 36° Y-cut lithium niobate (LiNbO
3
) crystal, chosen for its superior thermal stability compared to traditional PZTs. The transducer consists of a lithium niobate crystal bonded to a steel cylinder. The transducer's electrical impedance and pulse-echo performance were evaluated during heating cycles from room temperature to 550 °C. Experimental results demonstrated that the transducer continues to operate at high temperature, showing its potential for high temperature NDT application. The electrical impedance magnitude stabilized after several heating cycles, and the electromechanical coupling coefficient remained consistent. The pulse-echo response at 550 °C exhibited a SNR of 23 dB, despite a shift in the echo position caused by thermal expansion and changes in the speed of sound in steel under high temperatures. The findings indicate that LiNbO
3
holds promise as a temperature-resistant ultrasound transducer for high-temperature NDT, without the issue of depoling.