Magnetic-electric composite coating with oriented segregated structure for enhanced electromagnetic shielding. (10th January 2022) - Zhang, Jijun
Highlights: Magnetic-electric composite coating with oriented segregated structure was designed. The composite coating shows enhanced EMI SE of ~41 dB, doubling the value of Al substrate. Magnetic-electric oriented segregated architecture can trap and change the propagation of radiations. The composite coating displays low thermal diffusivity, high hardness, and low wear rate. Abstract: Manipulation of the internal architecture is essential for electromagnetic interference (EMI) shielding performance of metal-based coatings, which can address the electromagnetic pollution in large-size, complex geometries, and harsh environments. In this work, oriented segregated structure with conductive networks embedded in magnetic matrix was achieved in Fe-based amorphous coatings via Ni–Cu–P functionalization of (Fe0.76 Si0.09 B0.1 P0.05 )99 Nb1 amorphous powder precursors and then thermal spraying them onto aluminum (Al) substrate. Benefiting from the unique magnetic-electric structure, the coating@Al composite delivered prominent EMI shielding performance. The EMI shielding effectiveness (SE) of modified coating@Al composite is ~41 dB at 8–12 GHz, doubling the value of Al substrate and is 15 dB greater than that of Ni–Cu–P-free coating@Al composite. Microstructure analysis showed that the introduced Ni−Cu− P insertions forcefully suppress the serious oxidation of the magnetic precursors during thermal spraying and form a dense conductive network in the magnetic matrix. Electron holography observation and electromagnetism simulation clarified that the modified coating can effectively trap and attenuate the incident radiations because of the electric loss from Ni−Cu− P conductive network, magnetic loss from Fe-based amorphous coating, and the electromagnetic interactions in the oriented segregated architectures. Moreover, the optimized thermal isolation and mechanical properties brought by structural improvement enable the coating to shield complex parts in thermal shock and mechanical loading environments. Our work gives an insight on the design strategies for metal-based EMI shielding materials and enriches the fundamental understanding of EMI shielding mechanisms. Graphical abstract: Image, graphical abstract