CASE STUDY | A Lead-free Piezoelectric Ultrasonic Transducer for High-temperature Operation

High-temperature, lead free piezo-materials for on-stream ultrasonic testing

Key Deliverables

• A novel lead-free piezoceramic has been developed and successfully deployed in to a high-temperature ultrasonic transducer.
• Alternatives to lead-based piezoelectric materials are available for extreme environment ultrasonic systems, mitigating risk of new products from changes in legislation.

Overview

In view of upcoming changes in legislation restricting the use of lead (Pb) in piezoelectric ceramic materials, Ionix have undertaken a development project with an industrial consortium to deliver alternative, lead-free materials to the ubiquitous lead zirconate titanate (PZT) for specific applications, including ultrasonic flow, level sensing and corrosion monitoring.
Presented here is an ultrasonic non-destructive testing transducer, manufactured with one of the output materials of the project, designed for use in high-temperature environments.

The Challenge

• There were a number of challenges around the material development for on-stream ultrasonic transducers which required a solution.
• No commercially available high-temperature lead-free materials existed with an activity >50 pC/N, which limits the applicability of the materials for ultrasonic generation and receive sensitivity.
• The material is required to be able to be withstand 500 °C for extended periods of time for operation in industrial environments such as Energy, Oil & Gas, and Nuclear.
• The material is required to be ‘plug and play’ with current materials – allowing for the use of existing manufacturing methods and processes, as well as compatibility with off-the-shelf gauges and electronics.

The Solution

• Ionix developed a unique high temperature piezoceramic, S1, which operates up to 550 °C long-term with similar material properties to Ionix current HPZ 580 material, but contains no lead, or rare earth metal oxides making for a sustainable, future proof supply chain.
• A piezoelectric element of S1 was assembled into Ionix standard HotSense™ HS582i ultrasonic transducer designed for corrosion surveys and mapping of on-stream plant.
• The transducer offers similar sensitivity and acoustic characteristics similar to that of a standard HotSense™ transducer, with a minor increase in the gain required for measurement.
• The transducer was able to be successfully calibrated, and used to accurately measure thickness of a 38 mm block of aluminium at 300 °C using a commercial, off-the-shelf ultrasonic thickness gauge.