Research Of Ultra-broadband Absorption Material Constructed By Honeycomb Structure

Microwave absorbing materials can effectively attenuate and absorb electromagnetic waves,which play an important role in national defense science and technology.With the development of radar detection technology in recent decades,the stealth capability of weaponry has been severely tested,requiring not only the ability to evade scanning by a single type of radar,but also absorbing materials with an absorption bandwidth covering multiple radar search bands.Honeycomb microwave absorbing materials are a kind of structural microwave absorbing materials that can expand the absorbing effect by multiple refraction and reflection,which can generate multiple reflection loss peaks in different frequency bands and show excellent absorbing ability in wide frequency range.So far,the research on honeycomb structured absorbers has focused on the study of multilayer composite honeycomb,but the research on the regulation method of absorber coating performance,the broadband absorption performance of honeycomb structure absorbing materials and the generation mechanism of multiple reflection loss peaks is less,and there is still no consensus on what values of electromagnetic parameters to use to judge the selection of absorber coatings.Based on this,this paper investigates the the absorber coating performance,absorbing properties and absorbing mechanism of honeycomb microwave absorbing materials.The main contents are as follows:(1)The graphite-coated honeycomb structure absorbing material were prepared using flake graphite as absorber filler,and the effect of graphite particle size on the absorbing performance was investigated.The composite coating showed the best absorption performance when the volume filling ratio was 35% and the graphite particle size was 5 μm,with three reflection loss peaks at 2.4 GHz(-33 d B),7.3 GHz(-22 d B),and 12.2 GHz(-19 d B).The absorption mechanism was then investigated using a symmetry model,and the results show that the absorption performance of the graphite peak nest absorbing material is mainly contributed by the high internal dielectric losses,and that the interference phase cancellation between the reflected waves at the interface is responsible for the strong reflection loss peaks.(2)In order to reduce the interfacial reflected waves and improve the wave absorption performance,a carbonyl iron coated honeycomb structure absorbing material was prepared using carbonyl iron micronized powder as absorber filler,and the wave absorption performance of the carbonyl iron honeycomb absorbing material at different ball milling times was investigated.When the volμme filling ratio was 35%and the carbonyl iron ball milling time was 8 h,the absorber coating showed the best absorbing performance with three reflection loss peaks at 1.4 GHz(-6.8 d B),4.2 GHz(-17.3 d B)and 7.2 GHz(-10 d B).Using a symmetry model to investigate the absorption mechanism,the application of the carbonyl iron coating reduces the reflected waves at the front interface,however,the weak loss capability of the carbonyl iron at low frequencies limits the expansion of the absorption bandwidth.(3)To further improve the wave absorption performance,composite absorber-coated honeycomb structured absorbers were prepared by compounding graphite with carbonyl iron to take advantage of both magnetic and dielectric losses.The performance of the honeycomb structured absorber material coated with the graphite/iron carbonyl complex coating(graphite: iron carbonyl = 35 vol%: 10 vol%)was significantly improved,producing three reflection loss peaks at 2.6 GHz(-37 d B),7.9 GHz(-22 d B)and 13.1 GHz(-17 d B),and the effective absorption bandwidth of the material reached 13.2 GHz.