High-Frequency Magnetic Properties of Compacted Fe-Mn-Ni Powder Coated with Phosphates Containing Various Metals

Our Fe–Mn–Ni soft magnetic powders have the potential to be applied to axial-gap motor stators and high-frequency transformer cores owing to their low coercivity and saturation magnetization equal to or higher than that of pure iron. Fe–Mn–Ni soft magnetic powders were fabricated by the reduction of Ni–Mn doped ferrite nanopowders with hydrogen gas at 1323 K. The magnetic powder cores were fabricated form Fe–Mn–Ni soft magnetic powders coated with the novel phosphate insulators containing various metals. Our group has developed a novel phosphate coating technology with improved thermal stability for iron-based alloy powders. Moreover, we investigated the effect of Ni–Mn doped nanoferrite on the magnetic properties of Fe–Mn–Ni soft magnetic powders and the high-frequency properties and structure of insulating phosphate layer containing various metallic elements coated on Fe–Mn–Ni alloy powders. The addition of several metals improves the highfrequency properties, resulting in an iron loss of 26.2 W/kg at 1 T and 400 Hz and a magnetic flux density of 1.64 T at 10 kA/m owing to the combination of rare-earth elements and transition metals.