High-efficiency electromagnetic ultrasonic transducer using laminated silicon steel sheet as back plate

Abstract

The invention discloses a high-efficiency electromagnetic ultrasonic transducer. The high-efficiency electromagnetic ultrasonic transducer is composed of a piece to be tested, an excitation coil, a laminated silicon steel sheet and a magnet. The laminated silicon steel sheet is located above the excitation coil, and the main plane of the laminated silicon steel sheet is perpendicular to the axialdirection of the excitation coil. The magnet is located over the laminated silicon steel sheet, and the magnet is magnetized in a vertical direction. The excitation coil is placed on the piece to be tested, and a plane formed by the excitation coil is parallel to the time surface. Both ends of the excitation coil are connected with the output end of an external pulse generator through leads, and apulsed current flows through the excitation coil to generate ultrasonic waves in the piece to be tested. The laminated silicon steel sheet is introduced to a conventional electromagnetic ultrasonic transducer as the back plate to reduce the magnetic resistance on a magnetic circuit around the excitation coil, so the dynamic magnetic field intensity and the eddy current density generated in the piece to be tested is increased, thereby the ultrasonic waves are enhanced, and the energy conversion efficiency of the electromagnetic ultrasonic transducer is improved.

Description

technical field [0001] The invention relates to electromagnetic ultrasonic non-destructive testing technology, in particular to an electromagnetic ultrasonic transducer with improved energy conversion efficiency. Background technique [0002] Electromagnetic ultrasonic transducer EMAT (electromagnetic acoustic transducer) is a transducer that uses electromagnetic coupling to excite and receive ultrasonic waves. It has the characteristics of high precision, no coupling agent, non-contact, suitable for high temperature detection, etc., and is often used For defect detection, dimension measurement, stress detection, etc. of metal rods, plates, pipes, etc. The mechanism of electromagnetic ultrasound is divided into two types: Lorentz force mechanism and magnetostrictive mechanism. The mechanism of Lorentz force is: the high-frequency pulse current is passed into the excitation coil, and the eddy current J is coupled in the metal sample due to electromagnetic induction, and the ...

AI Technical Summary

Problems solved by technology

Since the ferrite itself has a low saturation magnetic flux density (0.5T) and a low Curie temperature (450°C), it is easy to magnetically saturate the ferrite backplane under the superposition of a static magnetic field and a dynamic magnetic field. It leads to unsatisfactory improvement of its conversion efficiency, and the ferrite easily loses its magnetism in a high-temperature environment and loses the function of improving conversion efficiency

Images