複合セラミックスを用いた二層構造広帯域電磁波吸収体の作製と特性評価 Fabrication and Characterization of Double-layered Wide-band Electromagnetic Wave Absorber Consisting of Composite Ceramics
A wide-band electromagnetic wave absorber was developed using a double-layered monolith consisting of high- and low-permeability (μ<SUB>r</SUB>) composite ceramics. The low-μ<SUB>r</SUB> layer was formed from a powder mixture of Ni<SUB>0.7</SUB>Zn<SUB>0.1</SUB>Cu<SUB>0.2</SUB>Fe<SUB>2</SUB>O<SUB>4</SUB> and SiO<SUB>2</SUB>-based glass. Ferrite mixtures of low-firing Ni<SUB>0.2</SUB>Zn<SUB>0.6</SUB>Cu<SUB>0.2</SUB>Fe<SUB>2</SUB>O<SUB>4</SUB> and Ni<SUB>0.3</SUB>Zn<SUB>0.7</SUB>Fe<SUB>2</SUB>O<SUB>4</SUB> with less sinterability were used to adjust the densification characteristics of the high-μ<SUB>r</SUB> layer. Co-firing of green compacts of the ferrite: glass powder (90:10% in mass-base) for the low-μ<SUB>r</SUB> layer and low-firing ferrite: less-sinterable ferrite (60:40% in mass-base) for the high-μ<SUB>r</SUB> layer resulted in the production of a monolithic double-layered ceramic at 1100°C. Scanning electron microscopy and electron microprobe analysis of the monolithic double-layered ceramic showed that Ni-Zn interdiffusion and glass diffusion occurred across the layer boundary, leading to the diffusion bonding. An absorption band of the double-layered absorber was more than 10 dB in a wide frequency range from 6 MHz to 1.8 GHz.
粉体および粉末冶金 54(2), 86-92, 2007-02-15
Japan Society of Powder and Powder Metallurgy