Carbon/carbon composites with higher mechanical strength and better reliability at elevated temperatures are urgently needed to satisfy the practical applications requirements. SiC nanowires (SiCNWs) modified C/C (SC-CC) composites have attracted an abundance of attention for their excellent mechanical performance. To further boost the mechanical strengths of composites and maximize the reinforcing efficiency of SiCNWs, we introduce orthogonally structured graphene nanosheets (OGNs) into SC-CC composites, in which OGNs are grafted on the SiCNWs via chemical vapor deposition (CVD) method, forming SC-G-CC composites. Benefiting from the nano-interface effects, uniform stress distribution, strong SiCNWs/PyC interfacial bonding and elevated stress propagation efficiency in the PyC matrix are achieved, thus SC-G-CC composites accomplish brilliant mechanical properties before and after 1,600 °C heat treatment. As temperature rises to 2,100 °C, SiCNWs lose efficacy, whereas OGNs with excellent thermal stability continue to play the nano-interface role in the PyC matrix. Therefore, SC-G-CC composites show better mechanical performance after 2,100 °C heat treatment, and the mechanical strength retention rate (MSR) of interlaminar shear strength, out-of-plane and in-plane compressive strength of SC-G-CC composites reach 61.0%, 55.7% and 55.3%, respectively. This work proposes an alternative thought for maximizing the potentiality of nanomaterials and edifies the mechanical modification of composites.

Stealth materials with high dependability at elevated temperatures and outstanding mechanical properties are urgently needed for practical applications. As one-dimensional ultrahigh temperature ceramic (UHTC) materials, zirconium carbide whiskers (ZrCw) have attracted a great deal of attention due to their desirable mechanical and ablation resistance performance in high-temperature environments. We have successfully synthesized ZrCw using a carbothermal reduction technique without the introduction of metal catalytic in this paper. ZrCw shows a typically prismatic structure with the diameter of 1–2 μm and the aspect ratio of up to 250. The growth of ZrCw is controlled by a solid-liquid-solid (SLS) and vapor-solid (VS) compound mechanism in conjunction with the auxiliary action of mesophase Na₃ZrF₇. The ZrCw/paraffin hybrids achieve the minimum reflection loss (R_L(min)) of −25.77 dB at 13.28 GHz under the thickness of 1.25 mm, and reach an effective absorption bandwidth (EAB) of 3.04 GHz (14.96–18.00 GHz) with a thickness of only 1.0 mm. This work presents a promising approach for large-scale producing high-purity whiskers, and verifies that ZrCw has extensive application prospects in the field of stealth materials.