Effects of magnetic Fe content on the microstructure and microwave absorption performance of SiO2 coating CoFe-C porous polyhedral composite particles

In order to obtain materials with comprehensive microwave absorption performance for outdoor corrosive environmental applications, this paper constructed low-density CoFe-C porous polyhedrons with SiO 2 nanoparticles coating using ZIF-67 template, chemical synthesis, and sintering methods (abbreviated as CoFe-C@SiO 2 ). The different magnetic Fe contents (mass of raw material ferrocene) were used to adjust the microstructure and microwave absorption performance of CoFe-C@SiO 2 . The results show that after sintering, the C=N bond, C-N bond, and Co 2+ in ZIF-67 decomposed to generate Hcp-graphite C, Fcc-Co, and a small amount of CoO. Increasing Fe content reduced the reflection loss and increased the effective absorption bandwidth of CoFe-C@SiO 2 . The optimal absorption performance (a reflection loss of −58.3 dB, an effective absorption bandwidth of 5.41 GHz) at a thin thickness (1.70/1.73 mm) was obtained. The moderate attenuation constant and widest impedance matching band resulted in the optimal absorption performance. Dielectric loss was the primary loss mechanism of CoFe-C@SiO 2 . The simulation of radar cross section values confirmed the enormous potential of CoFe-C@SiO 2 to achieve stealth under radar detection by increasing the Fe content. Coating SiO 2 nanoparticles improved absorption and anti-corrosion performances of CoFe-C. This paper establishes a design strategy for high-performance radar-absorbing materials that are resilient to outdoor corrosion.