High temperature flexible ultrasonic transducers for structural health monitoring and NDT

Flexible ultrasonic transducers (FUTs) consisting of a 75 \u3bcm thick metal membrane, a piezoelectric composite with a thickness larger than 85 \u3bcm and a top electrode were developed for structural health monitoring (SHM) and non-destructive testing (NDT) applications. The piezoelectric films were made by a sol-gel spray technique. Its ultrasonic performance in terms of signal strength is at least as good as commercially available broadband ultrasonic transducers at room temperature. Onsite gluing and brazing installation techniques which bond the FUTs onto steel pipes for SHM and NDT purposes up to 100\ub0C and 150\ub0C are developed, respectively. The best thickness measurement accuracy of FUT at 150\ub0C was estimated to be 26 \u3bcm.Peer reviewed: NoNRC publication: Ye