Ablation mechanism of the SiZr_x/graphite composites under oxy-acetylene flame

To enhance the ablation resistance of graphite materials, the SiZr_x/graphite composites with varying Zr contents were prepared using a reactive melt infiltration (RMI) method. The SiZr alloy reacts with graphite to form carbides during the preparation process. Oxy-acetylene tests revealed excellent ablation resistance with a limited linear ablation rate of 0.17 μm/s and a mass ablation rate of 1.67 mg/s when Zr is 10 at % in the alloy. During the ablation process, the pores in the graphite matrix allowed the SiZr_xalloy to flow out and reacted with oxygen, forming an oxide layer composed of solid ZrO₂and molten SiO₂phases. The molten SiO₂phase is capable of repairing the oxide layer, while ZrO₂and SiO₂react to form ZrSiO₄, which increases the viscosity of the melt. The solid ZrO₂serves as a framework for the oxide layer, providing attachment points for the molten SiO₂and ZrSiO₄, ultimately forming a dense solid-liquid mixed oxide layer.