POROUS METAL BACKING FOR HIGH-TEMPERATURE ULTRASONIC TRANSDUCERS
Résumé
Improving the performance of high-temperature transducers is a goal of major importance in many industrial applications. We propose to use porous metals as backing that supports high temperatures to enhance these performances. Thus, the acoustics properties acoustic of stainless steel and porous stainless steel with porosity of 25 % and 35 % are determined at ambient temperature and up to 400°C. Over the temperature range, the celerity variation is comprised between 5% and 6 % in the porous metals. We find that temperature does not significantly affect the attenuation in the material. The pulse-echo response and frequency response of a LiNbO3-based transducer with a porous backing are simulated using the KLM model. Simulations, compared to a reference transducer, show that the axial resolution with such a design endows these transducers to be used for imaging and/ or Non-Destructive Testing and Evaluation at high temperature.