Study on preparation and electromagnetic shielding properties of silver-coated ferrosilicochrome powder

Objective This study focuses on the preparation and properties of high-performance electromagnetic shielding materials for electronic equipment in marine environments.

Methods 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.

Results 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.

Conclusions The modified FeSiCr@Ag material has highly efficient electromagnetic shielding performance and good corrosion resistance properties.