Microwave absorption properties of in situ grown CNTs/SiC composites

CNTs/SiC composites were synthesized by pyrolysis of methane over SiC supported nickel catalysts. The composites show good microwave absorption ability in the frequency range of 2-18 GHz. The pyrolysis temperature has profound influences on the microwave absorption characteristic, and 700 °C is the most suitable temperature for preparation of the composites. The microwave absorption characteristic is also influenced by the Ni loading. By varying the Ni loading from 5 wt.% to 7.5 wt.%, the bandwidth of reflection loss below -10 dB can be broadened by 1.5 GHz under the same conditions. For the composite obtained from 7.5 wt.% Ni loading and the pyrolysis temperature of 700 °C, a minimum reflection loss of -37.6 dB can be obtained at 14.5 GHz with a thickness of 1.9 mm and the bandwidth of reflection loss below -10 dB can reach 5.1 GHz (from 12.4 to 17.5 GHz) with a thickness of 2 mm.