Carbon nanofiber aerogel/silicon oxycarbide composites for enhanced electromagnetic interference shielding

Abstract

Lightweight electromagnetic interference (EMI) shielding materials under harsh environments are in urgent need to tackle the increasing electromagnetic pollution and hazards. Herein, carbon nanofiber aerogel (CNFA) modified silicon oxycarbide (CNFA/SiOC) composites were prepared following a precursor infiltration pyrolysis procedure by using three-dimensional CNFA as a skeleton. Their structures and mass densities (0.28-1.35 g cm−3) were tunable by adjusting the content of polysiloxane precursor in impregnating solution. The lightweight CNFA/SiOC composite featured with continuous conductive network and highly porous structure in SiOC matrix, resulting in high specific shielding effectiveness (up to 68.9 dB·cm3 g−1 with SETotal of 19.3 dB) due to enhanced conductance loss and multi reflection/scattering. When increasing the density, the CNFA/SiOC composite can deliver EMI shielding effectiveness as high as 27.5 dB due to the generation of defective carbon and carbon dangling bonds as well as abundant interfaces between CNFs and SiOC which induce polarization loss. Moreover, the CNFA/SiOC composite exhibits good oxidation resistance with SETotal retention of above 98% after heat treatment at 600°C for 2 h in air, which arises from the effective protection of CNFs by SiOC.

Passive Filler-Loaded Silicon Oxycarbide Coating on Nickle Alloy with High Thermal Shocking Behavior and Oxidation Resistance

“…The PSO/Al 2 O 3 /YSZ slurry was continuously deposited on the K3 substrates, resulting in the increased thickness of the coating after the evaporation of ethanol solvent. The organic PSO precursor in the coating was further crosslinked by the hydrosilylation reaction of PHMS and D 4 Vi during the drying then transformed into an amorphous rigid SiOC network after pyrolysis [31]. Figure 1b shows a uniform and crack-free SiOC/Al 2 O 3 /YSZ coating with a size of 2.5 cm × 2.5 cm applied on the K3 substrate.…”

Carbon nanotubes/cellulose composite aerogels with controllable microstructure for electromagnetic interference shielding

“…[3][4][5][6][7][8][9][10][11] In addition, the 3D skeleton structure of porous composite materials is not only conducive to uniformly disperse conductive fillers and construct continuous 3D conductive networks, but also conducive to multiple reflection and absorption of electromagnetic waves (EMWs), forming the main EMI shielding mechanism with microwave absorption. [12][13][14] The 3D carbon nanofiber aerogel/silicon oxycarbide composite materials were prepared by Zhu et al 15 following a precursor infiltration pyrolysis procedure, which provided up to EMI SE of 27.5 dB. Yu et al 16 prepared anisotropic polyimide/graphene CNTs/cellulose composite aerogels by unidirectional freeze-drying, which exhibited a high EMI SE of 26.1-28.8 dB at a density of 0.076 g cm À3 .…”