The permittivity and microwave-absorbing properties of carbon black or carbon fiber filled alumina/ silica coating were investigated in X-band. The results indicate that both the real and imaginary part of the complex permittivity increase with the increasing content of carbon absorber. With the same content of carbon absorber, the coatings filled with carbon fiber show higher complex permittivity than the coatings filled with carbon black. As the absorber contents increase to 2wt%, the complex permittivity of the coatings decrease with the increase of frequency, which is so-called frequency-dependence dielectric response. The minimum reflection loss of the coatings shifts to low frequency region as their thickness increasing. The results of the microwave absorbing properties show that good microwave absorption ability (below -10 dB) can be obtained in the frequency range from 9.2 GHz to 12.4 GHz for the coating with 2wt% carbon black and 2 mm in thickness.%研究了炭黑或碳纤维填充氧化铝/二氧化硅吸波涂层在X波段范围的介电和吸波性能.结果表明:吸波涂层的复介电常数随着炭黑或碳纤维含量的增加而增大.当吸收剂含量相同时,填充碳纤维的吸波涂层比填充炭黑的吸波涂层具有更大的复介电常数.当吸收剂含量大于5wt％时,吸波涂层的介电常数在低频急剧增加,且随频率增大而减少,出现频散效应.反射率测试结果表明:吸波涂层的最大吸收峰随涂层厚度的增大向低频移动,当涂层中炭黑含量为2wt％、厚度为1.8 mm时,吸波涂层在9.2～12.4 GHz范围内反射率小于-10 dB,具有较好的吸波效果.
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