Effect of Binder Type and Content on High‐Frequency Permeability and Core Loss of FeNi, FeSi, and FeSiCr Soft Magnetic Composite Cores

Abstract

Abstract

Soft magnetic powder cores (SMPCs) are essential for high‐frequency power applications, yet their performance is critically dependent on the binder’s thermal stability and magnetic dilution effect. In this study, three high‐temperature resistant binders—silicone resin (denoted as MSE), silica sol (JN), and aluminum dihydrogen phosphate (PH)—were incorporated into FeNi, FeSi, and FeSiCr powders at four mass fractions (0.5–2.0 wt%). All three binders retain different amounts of residue after 500 °C annealing: PH shows the highest residual mass (62.1%), followed by JN (43.4%) and MSE (33.2%). All powder–binder combinations exhibit good frequency stability (100–1000 kHz), while permeability decreases with increasing binder content. Core loss measurements were performed at 1 MHz and B m = 0.02 T. The optimal formulation varies with powder type: FeNi and FeSi both achieve their optimal trade‐off with 1.0 wt% MSE; FeSiCr performs best with MSE across all contents ( P cv ~ 370 kW·m −3 , μ ′ ~ 55–60). Among the three systems studied, FeSiCr + MSE exhibits the best overall magnetic performance. This work provides a practical guideline for binder selection and content optimization in high‐temperature annealed soft magnetic powder cores.