| In modern warfare,the problem of equipment stealth has become increasingly prominent.In addition to the conventional stealth equipment of warplanes and submarines,more and more marine applications.Equipments have increased the demand for stealth.It is of great significance to develop functional coatings with stealth and anticorrosive properties.In response demand.At this stage,the method adopted on the ship is to apply an anticorrosive primer and a multi-channel absorbing thick coating on the sequence.This system design in the marine environment will lead absorbent failure,which leads to a decrease in absorption performance.At the same time,the heterogeneous structure leads to poor matching between the coating layers,more defects,and premature failure of the coating.Based on the idea of"integration of absorbing-anti-corrosion function",this paper combines the flaky graphene with barrier properties on the basic ferrite(Fe3O4)and the conductive polymer(polyaniline and polypyrrole)with poly dielectric properties and interface improvement function,which realizes the multifunctionalization of the filler.Further,by optimizing the composite process,adjusting the proportion of components and the conductivity of the polymer,a host absorbent with both absorbing and anticorrosive functions is prepared,and finally the organic coating having anticorrosive and absorbing functions is prepared by using the absorbent as a main filler in order to achieve multi-functional composite under the same system.In this study,the RGO/Fe3O4 precursor was prepared by co-precipitation method,and then RGO/Fe3O4/PANI(PPy)multi-functional absorbent was prepared by in-situ polymerization.The multifunctional absorbent filler could be obtained with small surface density,high absorption bandwidth and high absorption intensity by adjusting the composition ratio and the concentration of doped protonic acid.The components,microtography and structure of the composites were tested by XRD,FTIR,SEM and TEM.The results showed that the RGO/Fe3O4/(PANI/PPy)composite absorbent was successfully synthesized and the GO was better reduced.By means of in-situ polymerization,the conductive polymer and the binary absorbent form a good coating structure,and the ?-? bond of the graphene oxide is reduced to form a chemical bond between the two,thereby improving the interface state between absorbent filler and base resin.It can promote the dispersion of the filler in the coating,thereby further improving the compactness of the coating.The absorbing properties of the composites were screened by using a vector network analyzer.The result shows that the absorption intensity of RGO/Fe3O4 composite absorbent increases with the increase of the relative content of Fe3O4.Considering the conditions of microwave absorption performance and areal density,the composite ratio of the binary precursor is determined to be 1:4.At the ratio,the maximum reflection loss of the absorber is-62 dB(3.65 mm)and the bandwidth of-10 dB is 1.5 GHz.After grafting conductive polymer,RGO/Fe3O4/PANI has the best absorbing performance when the ratio is 1:4:0.5 and the doping concentration of hydrochloric acid is 0.5 mol/L.The maximum reflection loss is-47.6 dB(10.8 GHz),and the bandwidth of below-10 dB is 4.1 GHz(2.85 mm).The RGO/Fe3O4/PPy filler has the best microwave absorption performance when the component ratio is 1:4:0.5 and the acid concentration is 0.5 mol/L.The bandwidth of below-10 dB of the RGO/Fe3O4/PPy filler is 1.2 GHz and the maximum reflection loss is-46.4 dB when the thickness is 3.32 mm.By coating the conductive polymer on surface of RGO/Fe3O4,it can not only increase the interfacial polarization,but also promote the multilevel reflection of electromagnetic waves in the composite material.At the same time,its easily adjustable dielectric properties can improve the impedance matching of the ternary composite absorbent and improve absorption the effect and achieves light weight.Further research on the anticorrosion-wave absorbing properties of epoxy anticorrosive coatings prepared using RGO/Fe3O4(1:4)and RGO/Fe3O4/PANI(1:4:0.5,HCl concentration of 0.5 mol/L)as the main filler.The coating is based on a mixture of bisphenol A and bisphenol F,xylene is a diluent,polyamide is a curing agent,and the prepared multifunctional absorbent is added in an amount of 60 wt%and a coating having a thickness of 2 mm.The reflective absorption properties of the coating were tested using a bow test system.The results show that the maximum absorption of RGO/Fe3O4 coating is-12.6 dB and the bandwidth of below-10 dB is 3.5 GHz when the incident angle is 90.The maximum absorption of RGO/Fe3O4/PANI coating is-27.2 dB,and the bandwidth of below-10 dB is 4.2 GHz.The RGO/Fe3O4/PANI coating has a better absorption.The corrosion resistance of the coating was comprehensively investigated using sedimentation,electrochemical impedance spectroscopy(EIS),neutral salt spray,and mass method.The results are as follows:the impedance characteristic modulus of different immersion time |Z|0.01Hz results show that the overall corrosion resistance of RGO/Fe3O4/PANI coating is better than that of RGO/Fe3O4 coating.The results of the neutral salt spray resistance also confirmed that the RGO/Fe3O4/PANI coating was excellent in performance,and the RGO/Fe3O4/PANI coating did not show significant bubbling at 40 days,while the RGO/Fe3O4 coating was in 23 apparent bubbling appeared in the day.Further analysis of the reasons for its excellent performance found that the dispersion of RGO/Fe3O4/PANI filler in the coating system was better than that of RGO/Fe3O4 in the sedimentation experiment,and the coating of the conductive polymer improved the filler/base interface.At the same time,the water transport process research found that the saturated water absorption of RGO/Fe3O4/PANI coating was 1.4%,which was lower than 1.7%of RGO/Fe3O4 coating,indicating that the ternary composite coating has higher density,and RGO/Fe3O4/PANI coating reached a longer saturation time,indicating that the doping of flake graphene in the functional filler effectively acts as a retarder.In this study,a composite filler with anti-corrosion and wave absorbing function was successfully prepared and added to the model coating system to obtain good results.It provides a certain foundation for the study of high-efficiency absorbing and strong anti-corrosion composite coating. |
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