A simple method to insulate nanostructure Sendust alloy, suitable for mid-high frequency applications

Abstract

The Sendust alloy was prepared by mechanical alloying technique. The surface treatment process was carried out on the as-milled powders by hydrochloric acid, while irradiated by ultrasonic waves. EDS analysis indicated that surface-treated powders consisted of iron, silicon, aluminum, and oxygen elements. The FTIR spectrum of surface-treated powders had extra absorption bands related to aluminum oxides compared with as-milled powders. Results showed that although for cores made by surface-treated powders, both the real and imaginary parts of permeability decrease with respect to those for cores made by as-milled powders but significant reduction of imaginary part resulted in an increase in the quality factor remarkable. The cores were annealed in Ar atmosphere at temperatures 400, 500, and 600 °C for 1 h. The results show that the surface treatment process has led to a thermal stable coating layer on the Sendust powders up to 600 °C.