Design of light weight multi-layered coating of zinc oxide–iron–graphite nano-composites for ultra-wide Bandwidth microwave absorption

The present study focused on the formulation of suitable material combination for good microwave absorption with ultra-wide Bandwidth at minimum coating thickness. For this purpose, a unique materials combination of semiconductor, conductor and magnetic materials has been specifically designed through a simple fabrication method to meet the necessity of enhanced absorption characteristics in the frequency range of 4.0–12.0 GHz. The chosen bulk materials like zinc oxide (ZnO), iron (Fe), and graphite (C) have been subjected to high energy ball planetary mill for fabricating the nano-composites. The impact of milling time on microwave absorption behavior of zinc oxide–iron–graphite nano-composites has been studied. The maximum microwave absorption value of −17.40 dB has been obtained for 15 h milled sample with average grain size of ~10.0 nm for single-layer absorber of coating thickness 3.0 mm with broad Bandwidth of 6.43 GHz (4.0–10.43 GHz). The double-layer absorber has been optimized by multi-layering technique to increase the microwave absorption for less coating thickness. This type of material may be quite useful for radar cross section reduction at C and X-band.