Electromagnetic Wave Absorption Properties in Fe-based Nanocrystalline P/M Sheets with Carbon Black and BaTiO3 Additives

In order to increase the magnetic loss for electromagnetic (EM) wave absorption, the soft magnetic Fe73Si16B7Nb3Cu1 (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 540℃ for 1h to obtain the optimum grain size. The Fe-based powder was mixed with 2 wt% BaTiO3, 0.3~0.6 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 100℃ for 1h, the sheets of 0.5 mm in thickness were made by rolling at 60oC, 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 BaTiO3 and carbon black powder, which was caused by the increased dielectric loss of the additive powders.