No.4（2009）14.Precise Demagnetization with Direct and Alternating Current

Kiyoshi Itoh

   In measuring the magnetic properties and magnetic particle testing on magnetic materials or products, an accurate demagnetization of specimens is required. The effects of dc and ac current demagnetizing methods are investigated. In measuring the magnetic properties using ring specimens (a closed magnetic circuit), specimens cannot be demagnetized with an ac current demagnetizing method. With a dc current demagnetizing method, the maximum permeability and initial permeability differ from real permeability when the current inversion frequency is increased. When using a dc current demagnetizing method after an ac current demagnetizing method, specimens can be demagnetized precisely. In measuring magnetic properties using pillar specimens (an open magnetic circuit), specimens can be demagnetized precisely when using a dc current demagnetizing method after an ac current demagnetizing method.

Keywords

Demagnetization , Dc current demagnetizing, Ac current demagnetizing

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