Governing mechanisms of 2.5D/3D preform architectures on the microstructure, mechanical and ablation behaviors of C/C-SiC-ZrC composites

• Systematically studied 2.5D-to-3D preform effects on microstructure and properties. • Established structure–property relationship for performance-driven RMI design. • Fiber continuity and integrity are foundational for excellent mechanical properties. • High densification and uniform ceramics ensure superior ablation resistance. Preform structural design is a key strategy for achieving performance customization in ceramic matrix composites. This study selected three preforms with typical structural characteristics: 2.5D needle-punched, 2.5D stitched, and 3D orthogonal. The governing mechanisms of their architectural differences on the microstructure and macroscopic properties of C/C-SiC-ZrC composites fabricated by reactive melt infiltration (RMI) were systematically investigated. The results indicate that the straight and continuous fiber bundles in the 3D orthogonal architecture significantly enhance load transfer efficiency, increasing the tensile strength by 97.23 % and 65.66 % compared to the 2.5D needle-punched and stitched architectures, respectively. In contrast, the 2.5D needle-punched architecture promotes uniform distribution and high densification of the ceramic phase, exhibiting the best ablation resistance with linear and mass ablation rates of −1.36 ± 0.057 μm/s and 2.57 ± 0.178 mg/s, respectively. This study provides guidance for the preform design of ceramic matrix composites for extreme environments: the 3D orthogonal structure is suitable for high-load-bearing components, while the 2.5D needle-punched structure is specialized for ablation-resistant parts.