Development of multi-layer zinc oxide-iron composite coatings for microwave absorption

Abstract

Increasing demand for the Radar Absorbing Materials (RAM) draw the attention of research field towards the selection of a particular material for optimized absorption with minimum coating thickness. Composites of dielectric and magnetic materials are found to perform as good RAM’s in comparison of their individual absorption properties. On this basis, the microwave absorption properties have been studied for the zinc oxide-iron composites at X-band, where ZnO act as a good dielectric contributor and Fe exhibits good magnetic properties. Composites with different fractions of ZnO and Fe were prepared by blending individual powders of known particle size in the mortar pastel. The surface morphology of the as prepared pellets were charecterized and compared with the composition of the composites. From the determined values of complex permittivity and permeability the value of Reflection Loss (RL) has been calculated for all composites of single layer with different thickness. Maximum value of RL as -20.92 dB with a thickness of 2.1 mm was obtained for the composite with 60 wt% of ZnO. Multi-layering technique using genetic algorithm has been carried out in order to improve the reflection loss, bandwidth of absorption with good absorption and to minimize the coating thickness. The value of RL increased from -20.92 dB to -60.91 dB with a total coating thickness of 1.85 mm through the application of multi-layering technique. © 2014 American Scientific Publishers All rights reserved.