アルミニウム微粒子をポリスチレンに分散した複合電磁波吸収体の作製と評価

摘要

電磁波吸収体材料として軽量であり，作製が容易で，低rn環境負荷材料，資源の枯渇の問題を考慮に入れた安価で大rn量に入手できる材料が求められている。現状のフェライトrn等を用いた電磁波吸収体はSnoekの限界線が存在し，吸収rnする周波数帯が限られている。%We developed composite electromagnetic wave absorbers dispersed aluminum fine particles in polystyrene medium and evaluated those properties in order to realize single layer electromagnetic wave absorbers with the good absorption property in the GHz region. Polystyrene particles with two kind of diameters (approximately 200 μm or 1 μm) and aluminum fine particles were mixed by mechanical milling. Mixture was heated above the melting point of polystyrene and then cooled naturally in the air. The frequency characteristics of the complex relative permeability, the complex relative permittivity were calculated from values of the scattering parameters of the coaxial line loaded with a sample of a toroidal-core shape. Both the magnetization and the magnetic loss increased proportional to the volume mixing ratio of aluminum particles up to approximately 34 vol% for samples made of polystyrene particles with approximately 200 μm or 1 μm diameter. The diamagnetism was almost frequency independent and the magnetic loss decreased with increasing frequency for all samples. These results were in agreement with qualitative theoretical prediction.