Amorphous glass-covered magnetic wires for sensing applications

Abstract

Amorphous glass-covered magnetic wires consist of a cylindrical metallic core with diameters of 3 to 25 μm covered by a glass coating with a thickness of 2 to 15 μm, such wires being obtained directly from the melt by the glass-coated melt spinning method. Amorphous glass-covered wires were introduced in 1974 and were studied up to the early 1980s when they were disregarded; the appearance of in-rotating-water quenched amorphous wires attracted much more interest. These wires have been practically reconsidered in the last two years since their many application possibilities were not fully investigated during previous studies. In this paper we report the application related magnetic properties of the AGCMW from three important classes with respect to the sign of their magnetostriction constant λ: Fe-based (λ > 0). Co-based (λ < 0) and Co-based wires with a small amount of Fe (λ ≤ 0). We also present the tailoring possibilities for their magnetic properties, which are mainly determined for a given composition by the influence of their dimensional characteristics (metallic core diameter, glass cover thickness, their ratio) on these properties, thus offering a more powerful tool for controlling their magnetic behavior as compared to the case of in-rotating-water quenched wires. The advantages of using amorphous glass-covered wires in magnetic sensors and the basic operating principles of such sensors are also presented.