Effects of the Zn-phosphate coating on magnetic properties of Fe73.5Cu1Nb3Si15.5B7 nanocrystalline alloy powder cores

The effects of Zn-phosphate coating on the magnetic properties of Fe73.5Cu1Nb3Si15.5B7 nanocrystalline alloy powder cores have been investigated. The Zn-phosphate coating provided good electrical insulation between the magnetic particles through formation of an oxide and other compounds on their surfaces. The consolidated magnetic cores with powders treated in the solution of pH=1.3 acidity exhibited a permeability of 45, persisting up to about 2 MHz and a core loss of 500mW∕cm3 at the frequency of 50 kHz under the induction of Bm=0.1T. Furthermore, 62% permeability at 50 Oe of dc bias field was obtained. From these results, it was considered that the Zn-phosphate coating could be an effective method to form an efficient insulating coat even for small-sized Fe73.5Cu1Nb3Si15.5B7 nanocrystalline alloy powders.