含碳纳米管微波吸收材料的制备及其微波吸收性能研究

用竖式炉流动法,以二茂铁为催化剂,噻吩为助催化剂,苯为碳源通过催化裂解反应制备了碳纳米管,碳纳米管的外径为20-50nm,内径10-30nm,长度50-1000μm.分别以碳纳米管、羰基铁粉、碳纳米管与羰基铁粉的混合物为吸收剂制备了微波吸收材料,研究了上述三种微波吸收材料在2-18GHz的吸波性能,与纯碳纳米管和纯羰基铁粉微波吸收材料相比, 碳纳米管与羰基铁粉复合微波吸收材料在2-18GHz的吸收峰明显向低频移动.在含碳纳米管的微波吸收材料中,碳纳米管作为偶极子在交变电场的作用下,产生极化电流,电磁波的能量转换为其他形式的能量,瑞利散射效应和界面极化也是含碳纳米管微波吸收材料的主要吸波机理.

Preparation and Microwave Absorbing Properties of Microwave Absorbing Materials Containing Carbon Nanotubes

The carbon nanotubes being straight with a diameters of 20～50nm, internal diameter of 10～30nm and length of 50～1000μm were prepared by the catalytic decomposition of benzene using the floating transition method at 1100～1200℃. Benzene was used as carbon source and ferrocene as catalyst with thiophene. Three kinds microwave absorbing materials were prepared from carbon nanotube, carbonyl iron powder, carbon nanotube and carbonyl iron powder mixture and epoxy resin respectively. Microwave absorbing properties of these three kinds materials were investigated at the frequency range of 2～18GHz. The results show that the absorbing peak of carbon nanotubes and carbonyl iron powders composite microwave absorbing material moves to low frequency, compared with those of microwave absorbing materials containing only carbon nanotube or carbonyl iron powders. The carbon nanotubes used are as dipoles to absorb microwave. In the microwave absorbing materials containing an electromagnetic loss substance and dipoles, the dipoles as an electron couples generate an inductive current in the electromagnetic field. The induced current then causes a loss current and energy dissipation. And the Rayleigh scattering and interface polarization are main microwave absorbing mechanisms in the microwave absorbing materials containing carbon nanotubes.