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2011
Book Article
Title
Nondestructive Testing, 5. Magnetic and electromagnetic engineering
Abstract
Magnetic particles become attached to the surface and to some subsurface discontinuities when a ferromagnetic test piece is magnetized. The particles (e.g., iron or soft ferrite), which have high permeability and low coercive force, are coated with colored or fluorescent pigments for increased visibility. They are applied as dry particles or as suspensions in water or oil. Magnetic leakage fields of a discontinuity collect the particles, indicating their location, size, and shape by color contrast or fluorescence. Nonmagnetic materials cannot be tested with this method.