直流电弧法制备SiC@C核壳型纳米粒子及吸波性能研究

Microwave absoabsorbing properties of SiC@C core/shell nanoparticles prepared by arc discharge method

采用等离子直流电弧法,在氢气、氩气、甲烷分压分别为10、20、7.5 k Pa的混合气氛下制备纳米SiC@C核壳型复合粒子。利用XRD、Raman对纳米粒子的成分进行表征,用TEM对其形貌进行分析。将纳米SiC@C复合粒子均匀分散在石蜡基体中,在100 MHz^18 GHz频率内测定其复介电常数。结果表明,当电磁波吸收材料匹配厚度为8 mm、测试频率为9.49 GHz时,最大反射损耗能达到-27 d B。对SiC介电特性分析进一步表明,SiC中的C空位(VC)和Si空位(VSi)产生的偶极子发生的弛豫过程和SiC缺陷带来的电导率变化是影响介电性能的关键因素。

The SiC@C nanoparticles were prepared under mixed gas(the partial pressure of H_2,Ar and CH_4 is 10 k Pa,20 k Pa and 7.5 k Pa,respectively)by the direct- current arc method. The XRD and Raman spectrum were used to characterize the composition of SiC@C nanoparticles,and TEM was used to analyze their morphologies. The SiC@C nanoparticles were dispersed evenly in the paraffin matrix. The complex permittivity of the composite was measured at 100 MHz-18 GHz frequency range. It is found that the maximum reflection loss can reach-27 dB when the microwave absorbing layer is 8 mm thick. Further analysis on the dielectric properties of SiC@C nanoparticles shows that the dipole relaxation comes from the(VC)vacancy and(VSi)vacancy in the SiC. The change of the electrical conductivity and relaxation process is the main influencing factor on the dielectric properties of the SiC@C samples.