Microstructure, Mechanical and Cyclic Ablation Properties of C/C-SiC-(Zr,Hf)C-(Zr,Hf)Si2 Composites with Embedded Architecture via Low-Temperature Reactive Melt Infiltration

Abstract

To enhance the mechanical performance and ablation resistance of carbon fiber reinforced ceramic matrix composites, C/C-SiC-(Zr,Hf)C-(Zr,Hf)Si2 composites with embedded architectures were prepared using the porous C/C composites filling resin-derived porous carbon (RPC) as green bodies via the low-temperature reactive melt infiltration. The microstructure of the C/C-SiC-(Zr,Hf)C-(Zr,Hf)Si2 composites was examined, and a comprehensive analysis was conducted on microstructural evolution, mechanical and cyclic ablation properties. Results revealed that RPC achieved low-temperature rapid densification of C/C-SiC-(Zr,Hf)C-(Zr,Hf)Si2 composites while maintaining carbon fiber structural integrity. Simultaneously, RPC-mediated heterogeneous nucleation promoted the formation of an embedded carbide/silicide matrix with enhanced phase stability. The synergistic interplay of the intact fiber reinforcement and embedded matrix endowed the C/C-SiC-(Zr,Hf)C-(Zr,Hf)Si2 composites with superior load-bearing capacity, exhibiting flexural strengths of 300.9 ± 12.0MPa at room temperature and 228.1 ± 7.3MPa at 1600 °C, accompanied by stable modulus retention. Furthermore, the C/C-SiC-(Zr,Hf)C-(Zr,Hf)Si2 composites demonstrated outstanding ablation resistance during three cumulative 600s cycles under 1900–2000 °C oxyacetylene flames, showing linear and mass ablation rates of -0.063 μm/s and 0.352mg/s, respectively. This superior ablation resistance originates from the homogeneous biphasic protective structure facilitated by embedded architecture, featuring a thermally stable (Zr,Hf)O2 refractory layer synergistically integrated with self-healing Si-Zr-Hf-O glassy phase.