Microwave absorption properties of Ni/C@SiC composites prepared by precursor impregnation and pyrolysis processes

In the present study, the unique three-dimensional graphene coated nickel (Ni/C) foam reinforced silicon carbide (Ni/C@SiC) composites were first obtained via the precursor impregnation and pyrolysis (PIP) processes. The microstructure images indicated that the SiC fillers were successfully prepared in the skeleton pores of the Ni/C foam. The influence of the PIP cycles on the microwave absorption performances was researched, and the results indicated that after the primary PIP process, Ni/C@SiC–I possessed the optimal microwave absorbing performance with a minimum reflection loss( RL ) of −25.87 dB at 5.28 GHz and 5.00 mm. Besides, the RL values could be below −10.00 dB from 5.88 GHz to 7.74 GHz when the corresponding matching thickness was 3.85 mm. However, the microwave absorption properties of Ni/C@SiC-II and Ni/C@SiC-III were tremendously degraded as the PIP times increased. At last, the electromagnetic parameter , dielectric loss , attenuation constant as well as impedance matching coefficient were further investigated to analyze the absorbing mechanism, which opened a new path for the certain scientific evaluation of the absorbing materials and had extremely important to the defence technology.