Electromagnetic Acoustic Transducer (EMAT)
Definition - What does Electromagnetic Acoustic Transducer (EMAT) mean?
An electromagnetic acoustic transducer (EMAT) is a device that is used for ultrasonic testing of parts or materials. Because it uses electromagnetic properties to detect discontinuities in a material, an electromagnetic acoustic transducer does not require physical contact with the material being inspected, unlike other forms of ultrasonic inspection.
Corrosionpedia explains Electromagnetic Acoustic Transducer (EMAT)
An electromagnetic acoustic transducer is comprised of several components, including an electrical coil, a magnet (either an electromagnet or a permanent magnet) and a housing for the components.
Several things occur when an electromagnetic acoustic transducer is used to perform nondestructive evaluations. When switched on, electricity is sent through the electrical coil, which creates eddy currents. These eddy currents interact with the magnet in the transducer. The interaction creates a sound that originates in the material being inspected. This differs from other ultrasonic transducers that originate the sound within themselves. The sound created in the material being inspected by the electromagnetic transducer is captured and interpreted to determine the number of discontinuities and defects in the material, if any.
There are a number of key advantages that electromagnetic acoustic transducers provide. Perhaps the most important advantage is that they do not need to contact the material they are being used to inspect, although they do need to be somewhat close to them. This allows for high temperature and limited access inspection. Furthermore, electromagnetic acoustic transducers do not require a couplant. This reduces mess and waste during the ultrasonic inspection process. Because no physical contact is required, the surface condition of the material being inspected is less important than with other ultrasonic inspection methods.