Submicron α-Fe/polyamide composite absorber coating by low temperature high velocity air fuel spray technique

The composite absorbing coating is preferential in the microwave absorber, usually covering on the metals substrate. In this paper, the submicron α-Fe/polyamide absorber composite coating was deposited by a Low Temperature High Velocity Air Fuel spraying technique. The microstructure and the electromagnetic parameters of coating and powders were tested. It shows that the coating is dense and has a low porosity. Especially, α-Fe particles are injected into polyamide surface. And the microwave reflectivity coefficient of the coating was calculated with permeability and permittivity of the powders. There is a relationship between the mass fraction of composite powders and microwave absorption ability of coating. The microwave reflectivity coefficient of composite coating is high relative to the electromagnetic wave frequency. At the percolation threshold value (α-Fe content is about 0.75), the composite coating can absorb electromagnetic wave strongly. Additionally, with the increase of coating thickness, the minimal reflectivity coefficient moves to the low microwave frequency. There exists an appropriate coating thickness in order to absorb the electromagnetic wave energy largely. So the mass fraction and the thickness can affect the performance of this composite absorber coating.