Development of Radar Absorbing coating Using Polyurethane FR 2/55 with Barium Hexaferrite (BaFe12O19), Neodymium (NdFeB), and Graphite (C)

Abstract

The main objective of this study is to develop a Radar Absorbing coating (RAC) consisting of a base coat matrix, magnetic, and dielectric materials. The base coat used is FR 2/55 polyurethane topcoat, typically applied as a top layer in Eurocopter’s Super Puma helicopter. Barium hexaferrite (BaFe12O19) and neodymium (NdFeB) serve as magnetic materials, while graphite (C) is used as a dielectric material. In this study, three different material compositions were tested: 50%wt BaFe12O19 + 50%wt graphite, 50%wt NdFeB + 50%wt graphite, and 100%wt graphite, with a 30%wt filler addition to the base coat. Reflection loss measurements revealed optimal results for 50%wt BaFe12O19 + 50%wt graphite, achieving a maximum reflection loss of -2.88 dB at 12.00 GHz, and for 50%wt NdFeB + 50%wt graphite with a maximum reflection loss of -2.93 dB at 12.00 GHz. As a comparison, measurements of 50%wt BaFe12O19 + 50%wt graphite in four layers showed an increased reflection loss of -4.78 dB at 10.54 GHz. Although the results are far below the minimum absorption standard of 25 dB (50%), this coating can still be used as a RAC with a thicker layer.