High Orientation Fe-Si-Al Membrane Through Torque Model and Magnetic Field Design for Noise Suppressor

Developing microwave absorbing materials with excellent comprehensive properties is significant to solve the problem of electromagnetic noise pollution. In our works, the torque model of the sheet under the magnetic field was established to improve the orientation, based on the Maxwell simulation software, The simulation yields parallel and uniform magnetic lines of force that run through the sheet-like magnetic particles. Then a series of flaky Fe-Si-Al powder / polyvinyl alcohol (PVB) composite membranes were prepared by the tape casting process under the designed magnetic field. The μ ′ and μ ″ of the composite membrane treated with magnetic field orientation reach 159 (1 MHz) and 45 (10 MHz), respectively. The nonlinear regression method is used to analyze the complex permeability and evaluate the influence of domain wall displacement and spin rotation on the magnetic permeability theoretically. The S21 parameter is below −10 dB at frequencies above 2GHz for composite membranes with orientation magnetic field of 60 Oe, where its peak value reaches −55.6dB. The power loss ratio of the composite membrane is about 0.9 at the bandwidth of 1-7 GHz, which reaches 90% of the absorption efficiency. This outstanding comprehensive property is a result of the anisotropic demagnetizing factor of the flaky particles in a planar arrangement