Structure and electromagnetic properties of FeSiAl particles coated by MgO

FeSiAl particles with a layer of MgO surface coating have excellent soft magnetic and electromagnetic properties. In order to obtain the FeSiAl/MgO composites, Mg(OH)₂ sol prepared by sol-gel process was well-mixed with FeSiAl flake particles, and then treated by calcination at 823 K in vacuum. The microstructural, morphological and electromagnetic parameters of FeSiAl/MgO particles were tested. Accordingly, the electromagnetic wave reflection loss in the frequency range of 0.5–18 GHz was calculated. The results show that the surface coating increases coercivity Hc and decreases complex permittivity, leading to a good impedance matching. When the coating amount was 7.5%, reflection loss of the composite particles can reach to −33 dB. - Highlights: • This article reported the experiment of flaky FeSiAl particles coated with a layer of MgO. • After coating, the permittivity decreased obviously. • When the coating mount is 7.5%, the reflection loss is the lowest among the four samples.