A Study On SiC/Ni Heterogeneous Core-shell Type Nanoparticles Microwave Absorbing Performance

The core-shell type composite nanoparticles are combined with the central core and one or more other heterogeneous shells to form capsule structure, which was prepared by chemical or physical method. In improving the core chemical stability, the shell will bring unique electromagnetic and optical properties of heterogeneous material to core.Thus, the shell changs the inner particle surface activity, dispersion and stability performance, and can control the performance by thickness. So we obtain the ideal material for effective. In recent years, the preparation of well dispersive and stable core-shell nanoparticles have become a trend of composite materials and nano materials.In the mixed atmosphere (hydrogen:10 Kpa, argon:20 Kpa, methane:7.5 Kpa), we prepare the nano SiC@C core-shell type composite particles. Using XRD, Raman and TEM to characterize the composition of them. The SiC@C composite nanoparticles were dispersed evenly in the paraffin base, and the complex dielectric constants were measured between the frequency range 100 MHz-18 GHz.Then we discussed and analyzed their wave absorbing mechanism.By plasma arc discharge method, the particle were prepared in the atmosphere of CH42500 Pa,5000 Pa,1000 Pa, respectively.The size distribution of Ni@SiC@C double shell composite nanoparticles is about 20-50 nm. By XRD, RAMAN, XPS, STEM-HAADF and TEM, we characterized the composition and structure of sample. With dispersing composite nanoparticles into paraffin matrix, the electromagnetic parameters were measured between the frequency range 100 GHz-18 MHz. Through analyzing the characteristics of double shell structure,the effects of SiC and graphite C on the dielectric properties of the sample, we know that the dielectric constant of the sample is mainly caused by the defects of SiC and graphite C,especially shell (Vc) vacancies and (Vsj) vacancies caused by the dipole polarizations. In order to make a further analysis on dielectric properties of SiC composite structure and understand how this material effect on the dielectric properties of samples,we know that the dipole relaxation process and the change of electrical conductivity take effect. The magnetic loss mechanism of nanoparticles is attribute to natural resonance. Finally, the calculation and analysis shows that the material has excellent absorbing capacity in the multi band.