Lead‐free versus PZT: Acoustic characterization of ultrasonic immersion transducers fabricated with lead‐free NBT‐BT piezoceramic

Abstract

Abstract An evaluation of the performance of a recently developed formulation of (lead‐free) Sodium‐Bismuth titanate – Barium Titanate (NBT‐BT) piezoceramic is presented through the construction and testing of several immersion transducers based around a new material formulation “Pz12” from CTS Ferroperm (Kvistgaard, Denmark). Results are intended to yield insight into the applicability of this lead‐free material for use within industrial, NDT, medical or underwater sectors through the reporting of experimentally realised performance characteristics. Results of several performance tests are reported including: pulse‐echo amplitude, electrical insertion loss, transducer efficiency, power output and transmitting voltage response (TVR). Benchmarking is provided against comparable lead zirconate‐titanate (PZT) based transducers using an industry standard Navy Type 1 (Pz26, CTS Ferroperm). Performance of the Pz12 transducers was found to exceed expectations, although was lower than that of the comparable Pz26 transducers. Pulse‐echo amplitudes indicated a −4.3 dB relative amplitude between lead and lead‐free variants with electrical insertion loss and transmitting voltage response both showing an average −3.1 dB between the Pz12 and Pz26. Electroacoustic conversion efficiencies of up to 52% are reported for the Pz12 transducers compared with a 62% maximum efficiency for the Pz26 variant. Temperature stability is also investigated in the 10–70 ˚C range.

Keywords

• environmental factors
• lead compounds
• sensors