A Comparative Study of Insulators on Magnetic Properties of Sendust Based Nanocomposite Powder Cores

In this study, Sendust (Fe85Si9.6Al5.4) nanostructure alloy was prepared bymechanical alloying and was characterized by X-ray diffraction. In addition, the alloy’smorphology and its distribution particle size were investigated by scanning electronmicroscopy method. The alloyed powders were insulated with 4wt% of three differentinsulating materials including polyvinyl alcohol, epoxy resin, and sodium silicate. Then,0.5 wt% zinc stearate was added as a lubricant and the composites were formed at apressure of 1600 MPa in a torodial die. These cores were annealed in Ar atmosphere at350 to 450 ºC for 1 h. Some of the magnetic parameters of the as-milled and annealedsamples were measured and compared with each other in the frequency range of 4 to1000 kHz. The results showed that polyvinyl alcohol is not a suitable insulating agentfor insulating this alloy. In addition, the real part of the initial magnetic permeability ofthe magnetic powder core insulated by sodium silicate in comparison with that insulatedby epoxy resin is a bit smaller, but more reduction of the imaginary part of formerresults in an increase the Q-factor throughout measuring frequency range. The resultsshow that annealing is more effective on improvement of the measured magneticproperties of the samples insulated with sodium silicate than that insulated with epoxyresin.