Magnetic Viscosity Characterization of Fe–Nd–B Permanent Magnets Using a Novel Measurement Approach

Abstract

A new measurement method is presented for determining the magnetic viscosity parameter ( ${S}_{v}$ ) of permanent magnets (PMs) in various sizes and grades. $S_{v}$ , which describes the long-term stability of magnetic materials during operation, is measured using a setup with a magnetic yoke made of electrical steel enabling fast field changes. The measuring routine involves a sequence of small and large field pulses to determine direct and time-dependent losses, forming the basis for $S_{v}$ . Each measurement across several field stages is completed within 1 h, without the special sample preparation required by vibrating sample magnetometry (VSM) measurements. The effectiveness of this approach is confirmed by strong agreement with VSM measurements performed on different magnet types and at different temperatures.