科研之友
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摘要
To produce lightweight microwave absorbers, conductive and magnetic microspheres are fabricated through electroless plating of Ni-Fe films on hollow microspheres and their high-frequency electromagnetic and microwave absorbing properties are investigated in composite specimens. The electroless plating of the Ni-Fe films is conducted using a two-step process of surface sensitizing and metal plating. It is found that controlling the film composition (Fe content) and the amount of microspheres in the rubber matrix is important for producing zero-reflected absorbers. The complex permeability spectrum is not greatly changed with an increase of Fe content from 10% to 20% in the Ni film, while the dielectric constant and dielectric loss are sensitively reduced with Fe substitution by lowering the electrical conductivity. The complex permeability and permittivity increases with an increasing amount of microspheres in the composites. The matching frequency and matching thickness is estimated in a solution map of impedance matching with variation of the film composition and the amount of microspheres. For the composite of microspheres with Ni-20%Fe thin film and appropriate particle loading (M/R = 0.5), the impedance matching is satisfied in the GHz frequencies and the corresponding matching thickness is estimated to be 3-5 mm. This prediction is consistent with the reflection loss measured in the composites.
- 出版日期2016-12-5
