Integrated high-temperature piezoelectric plate acoustic wave transducers using mode conversion

Area of Science:

• Materials Science
• Non-destructive Testing
• Acoustics

Background:

• Piezoelectric films are crucial for ultrasonic transducer applications.
• Aluminum (Al) is a widely used metallic material in various industries.
• Non-destructive testing (NDT) methods are essential for material integrity assessment.

Purpose of the Study:

• To develop and evaluate integrated ultrasonic transducers (IUT) for defect detection in aluminum plates.
• To investigate the excitation and detection of various plate acoustic waves (PAW) using mode conversion.
• To assess the performance of IUT in detecting line defects at elevated temperatures.

Main Methods:

• Direct coating of piezoelectric thick films (>66 microm) onto aluminum substrates via a sol-gel spray technique.
• Fabrication of integrated ultrasonic transducers (IUT) with a top electrode.
• Utilizing IUT at the edges of metallic plates to excite and detect symmetrical, antisymmetric, and shear horizontal PAW through mode conversion.
• Pulse-echo mode operation for defect detection in 2 mm thick aluminum plates.

Main Results:

• Line defects (1 mm width, 1 mm depth) in 2 mm thick aluminum plates were clearly detected up to 150°C.
• Shear horizontal PAW demonstrated superior performance for line defect detection in the tested aluminum plates.
• Experimental findings showed good agreement with results from a finite-difference-based simulation method.

Conclusions:

• Sol-gel spray coated piezoelectric films enable effective integrated ultrasonic transducers for NDT.
• Shear horizontal PAW are highly suitable for detecting line defects in aluminum plates, even at elevated temperatures.
• The developed IUT system offers a promising approach for in-situ inspection of metallic structures.