C f /SiC-ZrC renowned for its outstanding performance as a thermal protectant, has gaining widespread recognition. Recent research on this system has emphasized the development of a cost-effective and reusable version with increased thickness for extended use in thick-walled thermal structural components. Ablation resistance, high strength retention, and high thermal conductivity are crucial for successful aircraft reentry. In this study, a low-cost reactive melt infiltration (RMI) method is developed for preparing dense and high-performance large-thickness C f /SiC-ZrC (L-C f /SiC-ZrC) with a gradient-structured matrix. The use of a fine weave-pierced fabric preform structure enhances both the structural integrity and thermal conductivity of C f /SiC-ZrC in the thickness direction. Simultaneously, the gradient-structured matrix, with appropriate contents of surficial ZrC and SiC exhibits erosion resistance, where the internal core with a high SiC content ensures remarkable strength retention. This unique matrix-structure design is achieved by integrating porous C with a single-stage pore structure and a high degree of graphitization degree, and a Si-Zr alloy with a unique composition. The 20mm thick C f /SiC-ZrC obtained via RMI has a density of 2.79 g/cm 3 with an open porosity of 5.65% and flexural strength of 224.3±5.4 MPa. Under a heat flux of 4.186 MW/m 2 , C f /SiC-ZrC exhibits an ablation rate of −0.004 mm/s after 60 s, demonstrating its resilience against ablation damage. Moreover, the post-ablation strength (166.0±4.4 MPa) exceeds that of reported C f /SiC-ZrC congeners, highlighting the robust load-bearing capability.
Xiaowu Chen,Shaoming Dong,Yanmei Kan,Xihai Jin,Haijun Zhou,Dewei Ni,Dengke Wang
Three-dimensional C f /SiC-ZrC-ZrB 2 composites were fabricated by reactive melt infiltration of ZrSi 2 alloys into porous C f /B 4 C-C preforms prepared through a sol-gel process. The influence of pore structure of the C f /B 4 C-C preforms on microstructure and mechanical performances of the C f /SiC-ZrC-ZrB 2 composites was studied. It was found that the microstructure and mechanical performances of the composites showed a strong dependence on the pore structure of the preforms. Residual ZrSi 2 content in the composites was significantly reduced with the decreases in the porosity and pore size of the C f /B 4 C-C preforms. At the same time, fiber erosion in the composites was also gradually mitigated, which led to a significant improvement in the fracture behaviors of the composite, as failure mode of the composites changed from brittle to pseudo-plastic. When the porosity of the preforms decreased from 53.7% to 31.3%, the flexural strength of the composites increased from 53 MPa to 184 MPa.
Xiaowu Chen,Shaoming Dong,Yanmei Kan,Haijun Zhou,Jianbao Hu,Dengke Wang
Three-dimensional (3D) C f /SiC-ZrC-ZrB 2 composites were successfully fabricated by sol-gel process combined with reactive melt infiltration (RMI) method. With H 3 BO 3 and PVA as raw materials for gel precursor, a porous C-B 4 C matrix was first introduced into the 3D carbon fiber preform by impregnation of the gel precursor, followed by heat-treatments of pyrolysis and carbothermal processes at 1500 °C in Ar atmosphere . Then molten ZrSi 2 alloys were infiltrated into the 3D C f /C-B 4 C preform to obtain 3D C f /SiC-ZrC-ZrB 2 composites. Based on thermodynamic analysis , the formation mechanism of SiC-ZrC-ZrB 2 matrix was revealed. Oxidation resistance and ablation resistance properties of the fabricated 3D C f /SiC-ZrC-ZrB 2 composites were tested using a muffle furnace and a plasma wind tunnel equipment, respectively. The flexural strength of the as prepared composites and its strength retention after oxidation were evaluated. It is revealed that the 3D C f /SiC-ZrC-ZrB 2 composites showed superior flexural strength , good oxidation resistance and excellent anti-ablation properties.
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