| Title |
Electromagnetic Shield Effectiveness of Rubber Composites Containing Ag-coated Ni-Zn Ferrite Particles |
| Authors |
김종혁(Jong Hyuk Kim); 김성수(Sung Soo Kim) |
| DOI |
https://doi.org/10.3365/KJMM.2015.53.1.59 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
composites; magnetic properties; powder processing; computer simulation; electromagnetic shielding |
| Abstract |
The present investigation provides an electromagnetic shielding composition that comprises Ag-coated Ni-Zn ferrite microspheres dispersed in silicon rubber matrix. Shielding effectiveness is analyzed for both the far-field and the near-field on the basis of electromagnetic shielding theory. Ni-Zn ferrite spheres that were 50 μm size on average were prepared by spray drying and sintering at 1130 ℃. Ag layer was plated on the ferrite spheres by electroless plating. Conductive Ni-Zn ferrite spheres with uniform Ag layer were obtained through plating using a high concentration of Ag precursor. The most sensitive material parameters of the rubber composites containing the ferrite spheres with Ag plating are the high values of the real and imaginary parts of the complex permittivity. The space charge polarization between the conductive particles in the rubber matrix results in high values of the dielectric constant and dielectric loss. Due to the high dielectric constant of the composites, a high value of the shielding effectiveness is predicted for the electric field. However, the shielding effectiveness for the magnetic field is not very high due to the small magnetic permeability of the ferrite spheres. (Received January 22, 2014) |