A laminated carbon nanotubes/silicon boron carbonitride film for high-efficiency electromagnetic interference shielding with oxidation resistance

Abstract

Constructing layer-structured carbon/ceramic composites is promising for achieving high-performance and high-temperature electromagnetic interference (EMI) shielding materials, in which the rational composition and structural manipulation is critical. Here, a laminated SiBCN@CNTs/SiBCN film with a unique hierarchical structure is prepared using multi-layered carbon nanotubes (CNTs) films as the skeleton by alternatively stacking SiBCN@CNTs layers and SiBCN layers, and its thickness varies from 0.13 to 1.10 mm depending on the number of stacked layers (i.e., 1 to 6 layers) and the concentration of polyborosilazane precursor for impregnation (i.e., 10–70 wt%). Enlarging the thickness of the SiBCN@CNTs layers from 60 to 130 μm in the film or increasing their stacking numbers could both enhance the shielding effectiveness due to the introduction of additional interfacial and interlayer multi-reflection to extend the propagation path of electromagnetic waves for effective wave interference. Consequently, a high EMI shielding effectiveness of 49.4 dB has been achieved on SiBCN@CNTs/SiBCN-50-3, corresponding to a high specific shielding effectiveness (SETotal/d) of 182.9 dB mm−1, higher than previous pure ceramic shielding materials and carbon/ceramic composites. Moreover, because of the effective protection of SiBCN for CNTs, the SETotal of the film is still up to 23.9 dB after oxidation at 1000 °C for 2 h. Therefore, the laminated SiBCN@CNTs/SiBCN film represents an ideal candidate for high-efficiency EMI shielding material used in oxidation environments.