Mu-Metal Chemical Etching

Mu-Metal is a Nickel-Iron soft ferromagnetic alloy designed to serve as a low-frequency magnetic shielding material. It features high permeability and is often composed of 80% Nickel, 20% Iron, and small amounts of other metals, depending on the formula and design criteria.

When an externally applied magnetic field is present, Mu-Metal domains magnetically re-align and generate a new external field. The superposition of the two fields results in a lower observed field.

Mu-Metal Chemical Etching

Fotofab’s etching process produces designs that can withstand harsh indoor and outdoor environments. The process uses an acid (Ferric Chloride) to etch the unprotected parts of a metal surface to create a design or image formed to your project’s specifications.

Characteristics of Mu-Metal

Stronger than pure nickel, Monel alloys are resistant to corrosion by many agents, including rapidly flowing seawater. Other characteristics include:

  • High permeability with minimum hysteresis loss, which is ideal for a variety of magnetic shielding applications
  • Low reluctance path for magnetic flux, leading to its use in magnetic shields against static or slowly varying magnetic fields
  • Low coercivity, near-zero magnetostriction, and significant anisotropic magnetoresistance, which is critical for industrial applications where variable stresses in thin films would otherwise cause a ruinously large variation in magnetic properties

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Acid Etched Mu-Metal Applications

By varying the levels of Nickel, Iron, and other metals in Mu-Metal formulations, the alloy can exhibit differing levels of permeability and magnetic shielding properties. As a result, acid etching of Mu-Metal is used in a variety of applications, including:

Other Factors

  • Magnetic shielding from Mu-Metal works not by blocking magnetic fields but providing a path for the magnetic field lines around the shielded area
  • The best shape for shielding applications is a closed container surrounding the shielded space
  • The effectiveness of Mu-Metal shielding decreases with the alloy’s permeability, which drops off at both low field strengths and, due to saturation, at high field strengths
  • Also known as Hy-Mu 80™ and Permalloy80™

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