A New High-Temperature Ultrasonic Transducer for Continuous Inspection

Ultrasonic inspection at elevated temperatures remains a technical challenge due to material limitations. Standard transducers degrade at temperatures above 300 °C. Prior research has shown that high Curie temperature materials are essential for thermal stability. However, no prior work had resolved the acoustic coupling at such extremes. Existing studies focus on room-temperature performance. This gap motivated the search for a new transducer design. The need for continuous inspection in high-temperature environments is growing. No prior work had achieved a 90% bandwidth at 700 °C. This paper introduces a novel solution to meet industrial demands.

The aim is to develop an ultrasonic transducer for operation at 700 °C to 800 °C. High-temperature environments require stable signal transmission. The challenge lies in material selection and acoustic coupling. Lithium niobate was selected for its high Curie temperature. Porous ceramics were explored for acoustic impedance control. The study investigates bonding methods for thermal stability. The goal is to achieve a 90% 3-dB bandwidth at operating temperatures. This approach addresses a critical need in non-destructive testing.

Lithium niobate single crystal was used as the piezoelectric element. Porous zirconia was selected for the backing element. The pore volume fraction was controlled during manufacturing. The average pore diameter was adjusted for acoustic properties. A one-dimensional model predicted optimal impedance values. High-temperature adhesives and brazing alloys were tested for bonding. The transducer was evaluated for signal stability. Performance was measured as a function of temperature.

The transducer achieved a center frequency of 2.7-3 MHz at 700 °C. The 3-dB bandwidth reached 90%-95% at the operating temperature. Porous zirconia provided the necessary acoustic impedance. Lithium niobate maintained piezoelectric properties up to 1200 °C. Aluminum brazing alloy ensured stable bonding. Acoustic coupling was optimized using the ceramic matrix. Signal clarity was maintained across the temperature range. The design met the target performance metrics.

The transducer design enables ultrasonic inspection at 700 °C to 800 °C. Lithium niobate and porous zirconia are suitable for high-temperature use. The one-dimensional model accurately predicted impedance values. Aluminum brazing alloy provided stable bonding. The 3-dB bandwidth met the target range. The transducer produced clear signals at elevated temperatures. The design supports continuous inspection in industrial settings. The authors propose this as a viable solution for high-temperature environments.