Electromagnetic Wave Absorption Properties in Fe-based Nanocrystalline P/M Sheets with Carbon Black and BaTiO3Additives

Abstract

In order to increase the magnetic loss for electromagnetic(EM) wave absorption, the soft magnetic <TEX>$Fe_{73}Si_{16}B_7Nb_3Cu_1$</TEX>(at%) alloy strip was used as the basic material in this study. The melt-spun strip was pulverized using an attrition mill, and the pulverized flake-shaped powder was crystallized at <TEX>$540^{\circ}C$</TEX> for 1h to obtain the optimum grain size. The Fe-based powder was mixed with 2 wt% <TEX>$BaTiO_3$</TEX>, <TEX>$0.3{\sim}0.6$</TEX> wt% carbon black, and polymer-based binders for the improvement of electromagnetic wave absorption properties. The mixture powders were tape-cast and dried to form the absorption sheets. After drying at <TEX>$100^{\circ}C$</TEX> for 1h, the sheets of 0.5 mm in thickness were made by rolling at <TEX>$60^{\circ}C$</TEX>, and cut into toroidal shape to measure the absorption properties of samples. The characteristics including permittivity, permeability and power loss were measured using a Network Analyzer(N5230A). Consequently, the properties of electromagnetic wave absorber were improved with the addition of both <TEX>$BaTiO_3$</TEX> and carbon black powder, which was caused by the increased dielectric loss of the additive powders.