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)O 3 ceramics are the most common piezoelectric material used in piezoelectric sensors. However, Pb(Zr,Ti)O 3 ceramics face limited thermal stability and lead-related environmental risks, especially in high-temperature SHM. To address these challenges, we propose a lead-free 0.94K 0.5 Na 0.5 NbO 3 -0.06LiNbO 3 (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.