Pulsed electromagnet EMAT for ultrasonic measurements at elevated temperatures

Typically, permanent magnets are used in electromagnetic acoustic transducer (EMAT) design. Their use at high temperatures without active cooling is restricted because of their relatively low maximum operating temperature. Presented here is an alternative approach that overcomes this problem and that utilises a pulsed electromagnet and a ceramic encapsulated EMAT coil, both able to withstand high temperatures and capable of performing sample inspections at temperatures up to 600C, without using any active cooling system. Measurements on the shear wave velocity variations and ultrasound attenuation in a low-carbon steel sample at a range of different temperatures are presented here.