Condition monitoring with ultrasonic arrays at elevated temperatures

The ability to generate and detect ultrasound in test objects at elevated temperatures has potential applications in monitoring of industrial plant and processes. However, the design of an ultrasonic transducer capable of long-term operation at high temperatures is not straightforward and adaptions of conventional NDT designs have been complicated and expensive. In addition, a single- or dual-element transducer fixed in position can typically provide only single A-scans, limiting its usefulness for condition monitoring. In contrast, ultrasonic arrays can provide B-scan data which are more useful in themselves and can also be processed to form images of the interior of the test object. In this paper we describe the design of ultrasonic transducers for condition monitoring at elevated temperatures. Results are presented from a composite material made with lithium niobate and high temperature cement, followed by an outline of the areas to be considered in further work.