Microstructure and ablation properties of ZrC-SiC/(C/C) composite prepared by reaction melting infiltration

Reaction melt infiltration (RMI) was adopted to prepare ZrC-SiC/(C/C) composites with a density of 3.288 g/cm³. The analysis methods such as SEM-EDS, XRD and TEM were used to discuss the microstructure of ZrC-SiC/(C/C) composites. The results show that the ceramic phase has been fully and uniformly filled in the matrices of C/C composites, whose internal structure mainly consists of ZrC, SiC, pyrolytic carbon(PyC) and carbon fiber(CF). The infiltrant reacted fully and no residual metals Zr and Si were detected in the composites. The ablation properties of ZrC-SiC/(C/C) composites were determined at 2 500℃ after ablation for 30 s, 60 s and 90 s with the oxyacetylene ablation equipment. The mass ablation rates are 5.667 mg/s, 2.907 mg/s and 3.030 mg/s and the linear ablation rates are 1.001 μm/s, 4.662 μm/s and 4.450 μm/s. Test ablation results show that the ceramic phase in the ablation center of ZrC-SiC/(C/C) composites is gradually oxidized to produce ZrO₂ and SiO₂ during the high-temperature ablation. The resulting binary glassy mixture protects and fills the ablation pores of the composites, so as to avoid the occurrence of oxidation reaction in the composites and improve the ablation properties of such materials effectively.