Preparation And Wave Absorption Properties Of LAS/rGO Composite Materials

In this paper,a novel graphene-based ceramic wave absorbing composite with excellent absorbing properties was prepared by three steps of sol-gel method,solvothermal method and heat treatment.The dielectric constant r GO was combined with the permeable LAS material,and the silane coupling agent aminopropyltriethoxysilane(KH-550)was added to enhance the interfacial bonding of r GO and LAS particles.The LAS particles on the r GO surface were capacitor type.The structure adjusts the impedance matching only by adjusting the dielectric constant of the composite material,and finally obtains the super-strong,ultra-wide and lightweight LAS/r GO-KH-550 composite material.Combined with SEM,EDS,XPS,XRD,FTIR,TEM and vector network analyzer,the effects of LAS,post-treatment temperature,and KH-550 on the absorbing performance of the composite were studied,and the absorbing mechanism was further analyzed.The results show that the self-aggregation of LAS particles in LAS/r GO composites is prone to occur,resulting in the non-dispersion and non-uniform distribution of LAS particles on the graphene surface.The wave absorption performance of LAS/r GO composite material is largely improved compared with that of pure r GO.The wave absorption performance of LAS/r GO composite material is significantly improved compared with that of pure r GO.The addition of LAS particles makes the dielectric constant of the material significantly lower than that of pure r GO,and with the increase of LAS,the dielectric constant becomes lower.When the mass ratio of GO:LAS is 1:1,the LAS/r GO composites have the best absorbing properties.At the frequency of 4.88 GHz and the thickness of 5.9 mm,the minimum reflection loss reaches to-28.82 d B.The thickness ranges is 2-6 mm and the maximum absorption bandwidth is 5.36 GHz.Using sol-gel method,hydrothermal reaction method and heat treatment method,the LAS nanoparticles were successfully loaded onto the graphene nanosheet by adding the silane coupling agent KH-550.LAS/r GO-KH-550 regulates the complex dielectric constant of r GO through LAS nanoparticles and KH-550,and has good microwave absorption performance.The best treatment temperature of LAS/r GO-KH-550 composite materials is 700 ℃.The GO content was 0.186 g,and the molar ratio of LAS to KH-550 was unchanged.The LAS/r GO-KH-550 composite had the best absorbing performance When the mass ratio of GO:LAS is 1:1.Its minimum reflection loss is-45.05 d B at the frequency of 16.8 GHz and the thickness of 2.5mm,and its maximum absorption bandwidth is 7.68 GHz.When the molar ratio of silane coupling agent KH-550 to LAS is 2:1,the effective absorption bandwidth of LAS/r GO-KH-550 composites in X and Ku band reaches 6.64 GHz with strong electromagnetic wave absorption capacity(RL=-62.25 d B),and the filling amount is only 20 wt.%.The effective absorption of LAS/r GO-KH-550 at all X and Ku bands(8-18 GHz)was lower than-20 d B(99.00%).The results show that the interfacial polarization,debye dipole relaxation,well-matched characteristic impedance and quarter-wavelength matching play an important role in improving the microwave absorption performance of LAS/r GO-KH-550 nanocomposites.Therefore,LAS/r GO-KH-550 nanocomposites can be used as ultra-wideband,lightweight and high-performance wave absorbing materials.