Acoustic stability and self-healing mechanism of nano-Ag coupled transducer for long-term high-temperature monitoring

Ultrasonic transducers play a critical role in structural health monitoring, particularly in high-temperature environments. In this work, nano-Ag coupled transducer is tested through insulation, cooling, and reheating stages to assess the acoustic performance and investigate underlying mechanisms. The results show that the stability of the resonance frequency indicated that its core acoustic properties are not significantly affected after operating at 350 °C for 60 h. Long-term high-temperature operation indicated a decline in SNR due to Kirkendall voids from non-equilibrium diffusion. Increases in the mechanical coupling coefficient and quality factor suggest a self-healing mechanism facilitated by grain boundary migration and atomic diffusion. Waveform distortions arose from thermal stress and mismatched thermal expansion coefficients in reheating.