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 by mechanical alloying and was characterized by X-ray diffraction. In addition, the alloy’s morphology and its distribution particle size were investigated by scanning electron microscopy method. The alloyed powders were insulated with 4wt% of three different insulating 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 a pressure of 1600 MPa in a torodial die. These cores were annealed in Ar atmosphere at 350 to 450 ºC for 1 h. Some of the magnetic parameters of the as-milled and annealed samples were measured and compared with each other in the frequency range of 4 to 1000 kHz. The results showed that polyvinyl alcohol is not a suitable insulating agent for insulating this alloy. In addition, the real part of the initial magnetic permeability of the magnetic powder core insulated by sodium silicate in comparison with that insulated by epoxy resin is a bit smaller, but more reduction of the imaginary part of former results in an increase the Q-factor throughout measuring frequency range. The results show that annealing is more effective on improvement of the measured magnetic properties of the samples insulated with sodium silicate than that insulated with epoxy resin.