Properties of iron-based soft magnetic composite with iron phosphate-silane insulation coating

This paper investigates the magnetic and structural properties of iron phosphate-aminosilane soft magnetic composites. FTIR spectra, EDX analysis and distribution maps show that the particle surface layer contains a thin layer of iron-phosphate with high coverage of powder surface. The phosphate layer decreases the loss factor and the imaginary part of permeability, as well as increasing the electrical resistivity and the operating frequencies. This layer, which lowers the electrical resistivity and the loss factor, is decomposed by the annealing treatment. The double-layer insulator increases the electrical resistivity and the operating frequency. The siloxane with high thermal stability does not decompose during the annealing treatment. This type of siloxane increases saturation magnetization, electrical resistivity and permeability but decreases microstrain and coercivity. (C) 2009 Elsevier B.V. All rights reserved.