INFLUENCE OF MODIFIED EPOXY COMPOSITES ON THE SHIELDING OF ELECTROMAGNETIC RADIATION OF HULLS OF AIRCRAFT AND MARINE UNMANNED VEHICLES

Abstract

The article investigates the influence of the composition and thickness of two-layer epoxy protective coatings on their shielding efficiency in the radar frequency range (8…12 GHz). The relevance of the work is due to the need to reduce the radar visibility of unmanned aerial vehicles and marine vehicles by creating effective radio-absorbing materials based on epoxy coatings. Modified 4,4-sulfonylbis(4,1-phenylene)bis(N,N-diethyldithiocarbamate) epoxy resin ED-20, which was polymerized with polyethylenepolyamine, was used as a binder. Three types of two-layer coatings were developed, which contain an adhesive layer (thickness 80±5 μm) filled with nanodispersed carbon compounds (technical carbon, fullerene-soot mixture, condensed carbon), and a functional layer filled with microparticles of industrial waste (converter, welding and granulated slags). The thickness of the functional layer was varied discretely (150, 300 and 400 μm). It was established that for coating 1 (technical carbon + converter sludge) and coating 2 (fullerene-soot mixture + welding slag) the optimal thickness of the functional layer is 300 μm. For coating 3 (condensed carbon + granulated slag) the optimal thickness is 400 μm. The highest shielding efficiency is provided by coating 2: at a frequency of 10 GHz SE = 40.1 dB, which is 4.3 dB higher than this indicator for coating 1 and 3.9 dB higher than for coating 3. The indicator SE = 35.8 dB was found for coating 1 with a functional layer thickness of 300 μm, and for coating 3 – SE = 36.2 dB with a thickness of 400 μm. It is proven that all the studied coatings exceed the engineering criterion of effective shielding (SE>30 dB), which confirms their practical suitability for protecting unmanned aerial vehicles from radar detection. The results of the work substantiate the feasibility of using industrial waste as functional fillers for shielding coatings, which ensures their economic feasibility and environmental safety. The results obtained create a scientific basis for further design of multilayer radio-absorbing materials with controlled and predetermined properties for the needs of the military-industrial complex and civil aviation.