Enhanced microwave absorption of flake-oriented Sendust sheets by tape-casting

Electromagnetic absorbers, consisting of the magnetic particles suspended in a nonmagnetic matrix, have been widely used in the telecommunication industry to suppress electromagnetic interference (EMI). The magnetic material absorbers are required to have high permeability in the vicinity of resonance frequency due to the increasing working frequency of next generation telecommunication devices. Among a variety of potential magnetic absorbers, metallic magnetic particles have been widely studied due to their large saturation magnetization, high permeability and high Snoek´s limit. Of particular interest is the shape anisotropy of magnetic particles that may give rise to higher products of permeability and resonance frequency, beyond that of the Snoek´s limit. However, because of the brittleness of flaky particles, it is difficult to retain flaky particles completely aligned along the plane of the sample by using rolling process. In this work, we aim to prepare oriented Sendust flakes in sheet form by tape-casting. The oriented Sendust sheets have potential to demonstrate superior microwave absorption performance at high frequencies (1~4GHz).