Tailoring of carbon structure in lightweight GNS/SiBCN nanocomposites for enhanced electromagnetic interference shielding performance

Precursor derived SiBCN ceramic is considered as promising materials for advanced electromagnetic interference (EMI) shielding. Here, the graphene nanosheet (GNS) aerogel via high-temperature graphitization was used as conductive network for constructing GNS/SiBCN nanocomposites through polyborosilazane (PBSZ) precursor infiltration and pyrolysis. The graphitization process of GNS aerogels increases the electrical conductivity of GNS/SiBCN nanocomposites from 105 to 1168 S·m−1, and achieves an improved EMI shielding effectiveness (SETotal) from 24.1 to 39.3 dB. The SiBCN protection endows the nanocomposite with good oxidation resistance at 800 °C in air and high-temperature stability at 1400 °C in Ar. Moreover, the porous GNS/SiBCN nanocomposite with density of 0.11 g·cm−3 was attained by adjusting the PBSZ content of 10 % during the infiltration, further exhibiting a high SETotal of 32.7 dB and a high specific SETotal of 297 dB·g−1·cm3. Therefore, it’s an ideal route to develop lightweight EMI shielding materials used in high-temperature environment. •Constructing conductive network in SiBCN using GNS aerogels via graphitization.•GNS network generates conductance loss for a high EMI SE of 39.3 dB.•SiBCN protection contributes to good oxidation resistance and thermal stability.•Porous structure provides multi-reflection for a high SSE of 297 dB·g−1·cm3.