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 (Fe_0.76Si_0.09B_0.1P_0.05)₉₉Nb₁ 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.

Key words: Fe-based amorphous coatings, Ni-Cu-P, Oriented segregated structure, Electromagnetic shielding