论文部分内容阅读
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 nano-SiC @ C core-shell composite particles were prepared by plasma direct current arc method under the mixed atmosphere of hydrogen, argon and methane partial pressures of 10, 20, and 7.5 kPa, respectively. The composition of the nanoparticles was characterized by XRD and Raman. The morphologies of the nanoparticles were analyzed by TEM. The nano SiC @ C composite particles were uniformly dispersed in a paraffin matrix and the complex dielectric constant was measured at a frequency of 100 MHz ~ 18 GHz. The results show that the maximum reflection loss can reach -27 d B when the electromagnetic wave absorption material matches the thickness of 8 mm and the test frequency is 9.49 GHz. The analysis of dielectric properties of SiC further shows that the relaxation process of dipole generated by C vacancy (VC) and Si vacancy (SiC) in SiC and the conductivity change caused by SiC defect are the key factors affecting the dielectric properties .