Dielectric-magnetic composite material that incorporate both dielectric and magnetic loss mechanisms are progressively emerging as the design paradigm for high-performance electromagnetic wave (EMW) absorbing materials. However, it remains challenging to combine dielectric and magnetic materials through a convenient structural design. Here, we report a core–shell structured Fe3O4@copper sulfide with multiple loss mechanisms, combining the typical magnetic component Fe3O4, which has excellent magnetic loss and impedance matching, with the dielectric component copper sulfide, which has high electrical conductivity and rich interfaces. Unlike the conventional hydrothermal synthesis method, the Fe3O4@copper sulfide core–shell structure is formed using the polymer-assisted electrodeless metal deposition (PAMD) method and a subsequent solution based sulfidation reaction. Attributed to the strong dielectric loss capacity introduced by copper sulfide nanosheets, Fe3O4@copper sulfide has an effective absorption bandwidth (EAB) of 5 GHz within 2–18 GHz at a filling ratio of 65 wt.% and a thickness of only 1.4 mm. In addition, we used the same possess to synthesize FeSiCr@copper sulfide, which also exhibited EMW absorption performance superior to that of the original magnetic component, verifying that the PAMD method is also applicable to other magnetic particles. Therefore, the proposed PAMD method provides a new solution-based strategy for constructing high-performance EMW absorbing materials with multi-component and multi-loss mechanisms.
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This study focuses on the preparation and properties of high-performance electromagnetic shielding materials for electronic equipment in marine environments.
The surface morphology, phase composition, electrical conductivity and ferromagnetic properties of the original ferrosilicochrome powder (FeSiCr) and silver-coated powder (FeSiCr@Ag) are analyzed with a scanning electron microscope, X-ray diffractometer, four probes and vibrating sample magnetometer, and a vector network analyzer is used to test the S parameters of the samples. A salt spray test chamber is used to simulate the corrosion behavior of the coating under marine environment conditions and observe its macro and micro morphology. Meanwhile, an electrochemical workstation is used to monitor the corrosion behavior of the coating in a mass fraction of 3.5% NaCl solution and study its corrosion mechanism.
The results show that the silver plating layer is compact and complete with the increase of the silver nitrate (AgNO3) addition. After electroless silver plating, the conductivity can reach 586.79 S/cm and the X-band shielding efficiency reaches 80 dB. After 96 h of accelerated corrosion in a humid heat and high salt spray environment, the surface of the resin coating prepared by FeSiCr@Ag shows no corrosion phenomenon. The self-corrosion potential of the coating before and after electroless silver plating is −0.4 V and −0.09 V respectively, indicating that the penetration rate of the corrosive medium into the coating slows down after silver plating, and a good corrosion inhibition effect is achieved.
The modified FeSiCr@Ag material has highly efficient electromagnetic shielding performance and good corrosion resistance properties.
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