Patent ID: 6009756
Filing Date: 2000-01-04
Classification: G01N

Abstract:
A device for detecting faults in a ferromagnetic material, said device comprising:an ultrasonic transducer including a plurality of permanent magnets, each permanent magnet having two poles of different polarity and producing a magnetic field, the plurality of permanent magnets being arranged so that adjacent permanent magnet poles have opposite polarities; and a high frequency current coil adapted to be connected to a high frequency current source to generate a high frequency field, for cooperating with the magnetic fields of the permanent magnets to excite horizontally polarized transverse ultrasonic waves in the ferromagnetic material; anda first premagnetizing magnet adapted to be positioned adjacent a surface of the ferromagnetic material, the first premagnetizing magnet having two pole pieces of different polarities, for producing a premagnetizing magnetic field in the ferromagnetic material,wherein the ultrasonic transducer is positioned between the pole pieces of the first premagnetizing magnet so that the premagnetizing magnetic field of the first premagnetizing magnet suppresses Barkhausen noise in the ferromagnetic material.