Investigation the effect of lubricant amount and annealing of powders on the magnetic properties of Sendust magnetic powder cores

In this study, Sendust alloy (Fe85Si9.6Al5.4) was fabricated by the mechanical alloy method. The obtained alloy was annealed for 2h at 1100 ͦC in the Ar atmosphere. Phase identification and morphology analysis of the milled and annealed powders were performed by X-ray diffractometer and scanning electron microscope, respectively. The results showed that the Sendust nanostructure solid solution obtained after 10h milling and after annealing the grains grew. The resulting alloy was insulated with sodium silicate adhesive and then mixed with various percentages of Zn- stearates from 0.25 to 0.75wt. %. These composites were formed by PM-method at 1600 MPa to obtain magnetic powder cores. The real and imaginary part of effective permeability and quality factor of the cores were measured with an LCR-meter. In addition, the results indicated that the green density of the core with 0.5% Zn-Stearate was higher than that of 0.25% Zn-Stearate and then remained constant. The magnetic properties of the sample were also optimized with 0.5% stearate. A comparison of the real part of permeability for the core with the unannealed and annealed powders showed that annealing of the powders resulted in an increase in the permeability and increased the Q-factor to frequencies below 200 kHz.