Laser ablative behavior of C/C modified by Si reactive infiltration

Carbon fiber-reinforced carbon matrix (C/C) composites were prepared by chemical vapor infiltration, and then they were subjected to silicon (Si) reactive melt infiltration to obtain C/C–SiC–Si composites. The ablation behavior of these two types of composites was evaluated by high-energy (500w) carbon dioxide laser irradiation under argon atmosphere. The depths and three-dimensional (3D) profiles of laser ablation holes were measured by laser confocal microscopy. The results showed that the depth of ablation hole of C/C composites gradually increased, and the ablation rate decreased with ablation time. The temperature distribution on C/C composite surface was simulated by 3D finite element analysis. The C/C–SiC–Si composites exhibited a rapid ablation rate during the ablation process within 7 s; however, no further ablation damage on carbon matrix was observed after 7 s. Si was found to dissipate energy through phase change, transpiration cooling, and smog attenuation. A laser ablation model was proposed based on the energy dissipation mechanism. C/C–SiC–Si composite showed better performance of laser ablation resistance in 100 s than pure C/C composite.