Acoustic emission: Is industry listening?

Abstract

Many forms of chemical analysis rely on absorbance or emission of electromagnetic radiation. However, until recently little attention has been paid to the interaction of acoustic waves with matter. This is somewhat surprising since even the early cavemen knew the value of using both visible and acoustic signals. Acoustic emission is potentially an ideal sensing tool: since it is non-invasive, analytical sampling considerations are minimal. Companies already use acoustic/vibration monitoring in the 0–30 kHz range for detection of leaks, wear, imbalance, and impending component failure. Of more interest to the chemist, perhaps, is the monitoring of higher frequency emissions from chemical reactions, phase transitions, and flow processes. Many chemical systems of industrial interest are acoustically active. Acoustic emission has many secrets to yield. Current studies remain limited by available transducers. Encouraging results have been obtained in this laboratory from several test systems investigated in collaboration with the Institute for Chemical Science and Technology and PAPRICAN. Some of these are discussed.