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Magnetic materials for security applications

  • US 5,368,948 A
  • Filed: 04/09/1993
  • Issued: 11/29/1994
  • Est. Priority Date: 01/09/1989
  • Status: Expired due to Fees
First Claim
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1. A magnetically active tag or marker which comprises a substrate;

  • an `active` magnetic material which is a soft magnetic material having a high magnetic permeability and a low coercive force; and

    a deactivating material which is a hard or semi-hard magnetic material having a moderate or high coercive force and a moderate magnetic permeability, whereby the deactivating material, when subjected to a sufficiently high magnetizing force, is able to clamp the magnetic properties of the `active` material so as to deactivate the `active` material, characterized in that said deactivating material consists of nickel with a columnar crystal grain structure and substantially isotropic magnetic properties in the plane of said substrate, said deactivating material being formed by electrodeposition, electroforming or electroless chemical deposition.

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