Three-dimensional CNT lamellae reinforced SiC for enhanced mechanical and electromagnetic shielding properties

Large-sized carbon nanotube lamella/silicon carbide matrix (CNT_L/SiC) composites were fabricated by infiltrating SiC into a lamellar CNT skeleton as a matrix, which avoids the uneven dispersion and high-temperature sintering damage resulting from easily agglomerated CNTs. Due to the highly aligned lamellar structure of the CNT_L, the compressive properties of the CNT_L/SiC composites were anisotropic and were increased by increasing the number of CVI cycles. The in-plane compressive strengths were higher than the out-of-plane compressive strengths. The flexural strength was as high as 240 ± 5 MPa after 6 CVI cycles. After fracture, the CNTs were pulled-out from matrix, indicating that the CNTs played the main role in bearing load, enhancing the mechanical properties. Since the CNT_L/SiC possessed numerous channels, the electromagnetic (EM) waves could be trapped and attenuated by repeated reflection and absorption, yielding outstanding electromagnetic interference (EMI) shielding effectiveness. The total shielding effectiveness (SE_T) values were significantly determined by the thickness and number of CVI cycles. Consequently, the SE_T values of the CNT_L/SiC reached 33.1–35.7 dB, which means that the EMI shielding effectiveness is excellent.