SiC(N)纳米粉体的吸波性能研究

Wave-Absorbing Property of SiC(N) Nano Powder

采用CVD法合成了SiC(N)纳米粉体.在NH3流量为0～480ml/min范围内,合成了氮原子百分含量随NH3流量逐渐增大的一系列SiC(N)纳米粉体.研究了SiC(N)纳米粉体的介电常数和介电损耗角正切与粉体组成的关系.发现介电常数的实部、虚部和介电损耗角正切均随粉体中氮原子摩尔分数的升高而降低.依据粉体的介电常数设计了双层吸波涂层,涂层的吸波效果随粉体氮含量的升高而降低.N原子取代SiC晶格中C产生的带电缺陷在电磁场作用下的极化弛豫是SiC(N)纳米粉体吸波的主要机理.

Some improvements are needed to increase the SiC's wave-absorbing ability. A method is used to dope SiC with other atoms. Nano SiC (N) powders are synthesized with the chemical vapor deposition (CVD) method. The formed SiC (N) nano powder is considered as SiC nano crystalline doped with nitrogen atoms. The SiC (N) nano powder is spherical and loosely agglomerates into particles within a range of 20-30 nm. The nitrogen content of the nano SiC (N) powder can be adjusted by varying the flow rate of NH3 in the preparation process. The microwave permittivity of the mixture of SiC (N) nano powder with paraffin wax was measured. The results show that the permittivity of the mixture change with the composition of SiC (N) nano powder. Both the permittivity and the dielectric loss of the mixture decreased with the increase of N mole content. Based on the measured data, double-layer wave-absorbing materials with 3 kinds of SiC (N) nano powder were designed. The thickness of the materials is 3 mm. The change of reflectivity with the frequency for these materials is also illustrated. It shows that the reflectivity decreases with the increase of N content in the SiC (N) nano powder.