Microstructure and ablation properties of a gradient Cf/C-XSi2-SiC (X = Mo,Ti) composite fabricated by reactive melt infiltration

Porous carbon/carbon composites were infiltrated by mixed Si-Mo-Ti powder with different Ti content below 1600 °C to produce an ablative Cf/C-(Mo,Ti)Si2-SiC composite. Microstructure, mechanical properties and ablation properties of the infiltrated composites were investigated. Results show that composites infiltrated by mixed powders with 14%wt Ti content have dense gradient structure and good mechanical properties. Three different kinds of typical morphologies can be distinguished on the surface of infiltrated composites according to the distribution of MoSiTi solid solutions. Formation mechanisms of the three kinds of typical morphologies are also analyzed. Ablation resistance improvement is attributed to the dense and continuity ceramic phases which distribute from inside to surface of the composites. Composites infiltrated with 14%wt Ti have the best ablation resistance due to the protective oxide layer formed by type I and type III morphologies during the ablation process. Linear and mass ablation rates of such composites are 0.002 mm/s and 0.01 mg/s, respectively.