Differential Single-Crystal Waveguide Ultrasonic Temperature Measurements Based on Magnetostriction

Area of Science:

• Materials Science
• Sensor Technology
• Physics

Background:

• Traditional ultrasonic temperature measurement faces limitations in extreme high-temperature environments.
• Existing methods often rely on sensitive flexural structures, impacting durability.

Purpose of the Study:

• To develop a robust ultrasonic temperature measurement method for harsh conditions (aerospace, industrial manufacturing).
• To overcome limitations of traditional sensors using a differential single-crystal sapphire approach.

Main Methods:

• Utilized two single-crystal sapphire waveguides of slightly different lengths as sensing elements.
• Measured time delay differences between end-face echoes to invert sound velocity and determine temperature.
• Employed COMSOL multi-physics v6.1 for optimizing magnetostrictive transducer bias magnetic field design.

Main Results:

• Demonstrated monotonic increase in sensor delay with temperature (300-1200 °C).
• Observed a downward trend in sound speed and repeatability error below 5%.
• Differential processing effectively suppressed common mode noise (300-700 °C) and maintained high sensitivity (>800 °C).

Conclusions:

• The differential single-crystal sapphire ultrasonic method provides a reliable and accurate solution for high-temperature monitoring.
• Optimized magnetostrictive transducer design improved energy conversion efficiency and high-temperature stability.
• This technology is suitable for extreme environments characterized by high temperatures and pressures.