Integrated and Flexible High Temperature Ultrasonic Transducers

Thick (> 40μm) ceramic films as piezoelectric ultrasonic transducers (UTs) have been successfully deposited on metallic and graphite/epoxy composite substrates by a spray technique. The characteristics of these UTs are that they (1) can be integrated directly onto the desired planar or curved substrates; (2) may not need couplant; (3) can operate in the transmission and pulse/echo modes with a signal to noise ratio more than 30 dB at 2-15 MHz; (4) can operate up to more than 400°C; (5) can be made flexible and (6) can be made as UT array. The capability using these UT for longitudinal and shear generation and receiving probe is demonstrated. Such films have been also deposited onto thin stainless steel membranes to form the flexible UT array for high temperature applications.