Electromagnetic properties of FeSiAl flaky absorbents coated with SBS by a dissolving-emulsifying process

Abstract

Flaky FeSiAl particles show excellent magnetic properties at low frequency but exhibit large permittivity and impedance mismatch at high frequency. The surface of the flake FeSiAl alloy particles was coated with thin layer of styrene-butadiene-styrene block copolymer (SBS) by a process consisting of dissolving organic polymer, mixing with the FeSiAl particles, emulsifying and then evaporating the solvent. Then the electromagnetic properties of the coated FeSiAl particles were studied. The results show that SBS forms a layer of thin, uniform and dense coating on the surface of the flake FeSiAl alloy particles, which significantly improves the resistivity of the alloy powder. The real part of the complex dielectric constant of the coated alloy particles mixed with paraffin 2:1 is decreased from 72 to around 30. The low frequency magnetic properties are not adversely affected, and its high-frequency performance is significantly improved due to the improvement of impedance matching. Therefore, the coating of SBS endow a better performance to the flaky FeSiAl alloy particles in broadband microwave absorption.

Keywords

• absorbent
• organic coating
• impedance matching
• microwave absorbing performance