High-entropy carbide ceramics (HECs) represented by (TiZrHfNbTa)C, as an important component of the new generation of ultra-high-temperature ceramics (UHTCs) system, have shown broad application prospects in extreme service environments such as spacecraft thermal protection systems, thanks to their excellent oxidation resistance and ablation resistance, extremely high melting points, and good hardness and strength matching. However, the inherent brittleness of HECs has become a key factor restricting their further application in ultra-high-temperature structural components. Carbon fibers possess remarkable characteristics such as low density, near-zero thermal expansion coefficient, ultra-high specific strength and specific modulus, and excellent thermal conductivity. The UHTCs-based composites constructed by introducing carbon fibers into the UHTCs matrix not only achieve a significant improvement in fracture toughness that is difficult for single ceramic materials to reach, but also possess comprehensive performance advantages such as low density, high mechanical strength, and excellent thermal shock resistance. However, the full play of the mechanical properties of UHTCs-based composites highly depends on an efficient load transfer mechanism between the fibers and the matrix, and the insufficient interfacial bonding strength has become a key bottleneck restricting their performance improvement.
Recently, a team of materials scientists led by Ouyang Haibo from Shaanxi University of Science and Technology in China was inspired by the physical interlocking mechanism in traditional Chinese mortise and tenon structures and proposed an interface design strategy based on the mortise and tenon structure.
This work not only explains the toughening mechanism and superior thermal shock resistance of the mortise-tenon-structured Cf/(TiZrHfNbTa)C-SiC composites, but also provides a feasible strategy for designing high-performance ultra-high-temperature ceramics composites suitable for extreme environments.
The team published their work in Journal of Advanced Ceramics on December 10, 2025.
"In this report, we deposit carbon microspheres onto the surface of carbon fibers to serve as "tenons" embedded into the (TiZrHfNbTa)C-SiC matrix, forming a mortise-and-tenon structure that creates a mechanically interlocked interface within the composite. Building upon this foundation, the introduction of TiC coating modification technology further achieves synergistic effects in chemical-physical bridging at the interface." said Haibo Ouyang, professor at School of Materials Science and Engineering at Shaanxi University of Science and Technology (China), an expert whose research interests focus on the field of ultra-high temperature ceramics material and composites.
"Thanks to this unique interface structure, the prepared Cf/(TiZrHfNbTa)C-SiC composite exhibits a flexural strength of 1053.33 MPa and a fracture toughness of 9.77 MPa·m1/2, which are 58% and 30% higher, respectively, than those of the samples without the mortise and tenon structure. Furthermore, this material exhibits outstanding thermal shock resistance, with a critical thermal shock temperature difference (ΔTc) of 802 °C, along with excellent ablation resistance, characterized by a linear ablation rate of 3.27 μm·s-1 and a mass ablation rate of 0.05 mg·s-1. These properties highlight its promising potential for applications in high-temperature and extreme environments." said Ouyang.
However, more systematic and in-depth research is still needed to fully verify the reliability and durability of the mortise and tenon structure in enhancing the performance of Cf/(TiZrHfNbTa)C-SiC composites. To this end, Ouyang also proposed two important tasks, including investigating the evolution of mechanical properties of the material under long-term exposure to ultra-high temperatures and the stability of its thermal shock resistance under cyclic thermal shock conditions.
Other contributors include Tianzhan Shen, Cuiyan Li, Mengyao He, Sirui Wu, Leer Bao, Qiaoqiao Wang from the School of Materials Science and Engineering at Shaanxi University of Science and Technology, China; Yulei Zhang from the School of Materials Science and Engineering at Northwestern Polytechnical University, China; and Jian Wei from the School of Materials Science and Engineering at Xi'an University of Architecture and Technology, China.
This work was supported by the National Natural Science Foundation of China (Nos. 52372087 and 52173299) and the Natural Science Foundation of Shaanxi Province (No. 2025SYS-SYSZD-062).
