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在1100～1200℃制备了直线形碳纳米管,外径为20～50 nm,内径10～30 nm,长度50～1000 μm.用化学镀工艺在碳纳米管表面均匀包覆了Ni-P和Ni-N合金,研究了它们的磁性能及其环氧树脂基复合材料在2～18 GHz的微波吸收性能.与纯碳纳米管相比,镀Ni-P合金碳纳米管复合材料的吸收峰向高频移动,镀Ni-P和Ni-N合金碳纳米管经热处理后,复合材料的吸收峰向低频移动.镀Ni-P合金碳纳米管以及镀Ni-P和Ni-N合金经热处理碳纳米管的矫顽力分别为304.34 Oe、 81.65 Oe、 183.85 Oe.随着矫顽力的增加,在2～18 GHz,复合材料的微波吸收峰向高频移动.在复合材料中,碳纳米管以及镀Ni-P和Ni-N合金的碳纳米管作为偶极子吸收微波.
The carbon nanotubes were prepared by catalytic decomposition of benzene using floating transition method at 1100-1200°C. Benzene was used as carbon source and ferrocene as catalyst with thiophene. The carbon nanotubes are straight with diameter 20-50 nm, internal diameter 10-30 nm and length 50-1000 μm. The Ni-P and Ni-N alloy coatings on the carbon nanotubes were deposited by electroless deposition technique. The magnetic property of Ni-P and Ni-N alloy coated carbon nanotubes and the microwave absorbing property of their composites at 2-18 GHz were investigated. Compared with the carbon nanotube/epoxy resin composites, the absorbing peak of the Ni-P alloy coated carbon nanotube/epoxy resin composites moves to the higher frequency. The absorbing peaks of the epoxy resin matrix composites containing Ni-P and Ni-N alloy coated carbon nanotubes after heat-treatment move to lower frequency. The coercive forces for the Ni-P alloy coated carbon nanotubes, Ni-P and Ni-N alloy coated carbon nanotubes after heat-treatment are 304.34 Oe, 81.65 Oe, 183.85 Oe respectively. It is found that the microwave absorbing peaks of the three different composites move to the high frequency with the increase of the coercive force. The carbon nanotubes or Ni alloy coated carbon nanotubes are used as dipoles to absorb the microwave.
Acta Materiae Compositae Sinica