Lead-Free Piezoelectric Ceramic Sensor for High-Temperature Aircraft Structural Health Monitoring

Structural health monitoring (SHM) is critical for ensuring the integrity and reliability of modern aircraft. Of the various SHM techniques, Lamb wave-based methods have emerged as particularly promising due to their ability to facilitate real-time monitoring and evaluation of aircraft structural integrity via integrated piezoelectric sensors capable of generating and receiving Lamb wave signals and advanced signal processing. Conventional Pb(Zr,Ti)O3 ceramics are the most common piezoelectric material used in piezoelectric sensors. However, Pb(Zr,Ti)O3 ceramics face limited thermal stability and lead-related environmental risks, especially in high-temperature SHM. To address these challenges, we propose a lead-free 0.94K0.5Na0.5NbO3-0.06LiNbO3 (KNN-LN) piezoelectric ceramic sensor. The KNN-LN ceramic exhibits excellent piezoelectric properties, superior thermal stability, and high sensitivity at elevated temperatures, with a 207 pC/N piezoelectric charge constant at room temperature and 489 °C Curie temperature. Experiments validate the ceramic’s stable performance from 25–200 °C with high sensitivity in aircraft structural damage detection. This development establishes a material foundation for next-generation SHM systems development, addressing aviation safety imperatives and environmental sustainability requirements.