MAGNETIC POWDER INSPECTION METHOD Russian patent published in 2013 - IPC G01N27/84 

FIELD: physics.

SUBSTANCE: method involves placing a magnetising device with an indictor packet filled with a magnetic liquid onto the surface of the inspected article. The magnetic liquid contains a liquid phase which contains 1-5% hydrochloric acid with concentration of 10-30%, and magnetic powder. The indicator packet is provided with two electric contacts lying inside it on one axis in form of two flat copper plates measuring 10×10×0.3 mm, which are placed perpendicular to the horizontal axis of the packet at a distance of 1-3 mm from each other. The inspected article is exposed to an alternating magnetic field. A defect is detected by visual monitoring of the position of particles of the magnetic powder in the indicator packet. If a defect is detected, the value of galvanic current of the magnetic liquid in the inspected zone is measured, followed by estimation of the size of the defect based on the measuring results.

EFFECT: high accuracy of quantitative estimation of defect parameters owing to higher measuring sensitivity with shorter inspection time.

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