Fabrication of gradient C/C-SiC-MoSi2 composites with enhanced ablation performance

C/C-SiC-MoSi2 composites with gradient composition and microstructure were prepared by a novel vacuum filtration infiltration (VFI) process with a later hydrothermal densification. The composition distribution, microstructure, density, porosity, thermal conductivity and ablation properties of the composites were investigated. Results show that the distributions of SiC and MoSi2 are homogeneous and gradient along the cross-section of the composites, respectively. From the inner part to the outer part of the composites, the increase in density and thermal conductivity is achieved. The outer part of the composites exhibits enhanced ablation performance. After being exposed to the oxyacetylene flame at 2000 °C for 30 s, the linear and mass rates of the as-prepared composites are only 0.0051 mm/s and 0.76 mg/s.