Microstructure and ablation behavior of SiMo/graphite composites with excellent short-time ablation resistance

Si-Mo alloy was infiltrated into porous graphite to develop a short-term low-ablative SiMo/graphite composite material. 19.4 vol.% residual Si was retained in the composites and significantly improved the short-term (less than 60 s) ablation resistance without sacrificing long-term (∼180 s) ablation resistance. The excellent short-term low-ablative performance is ascribed to the melt and evaporation of Si, which reduces the rate of temperature rise and supplies the consumption of SiO₂ in the ablation surface. With the progress of ablation time, the ablation surface forms a SiO₂-MoSi₂ double layer, which acts as a barrier between the oxyacetylene flame and the ablation surface.