石墨/AlSi耗散防热材料喉衬烧蚀试验研究

In order to improve the ablation resistance of graphite, AlSi alloy was infiltrated into the graphite pores by pressure infiltration method to obtain graphite/AlSi dissipative thermal-protective composites. Small solid rocket motor tests have been used to compare the ablation performance of graphite/AlSi composites throat and C/C composites throat under different propellant combustion and chamber pressure conditions. The study summarizes the effect of propellant aluminum content and combustion chamber pressure on the relative ablation performance and the corresponding anti-ablative mechanism of graphite/AlSi dissipative thermal-protective composites. Results show that the linear ablation rate of the graphite/AlSi composites throat is lower than that of the C/C composites throat under each attempted condition. In particular, the ablation rate of graphite/AlSi composites throat reduce by 92% compared to C/C composites throat when the aluminum content and chamber pressure are 5% and 12.5 Mpa, respectively. The AlSi alloy in the graphite pores absorbs heat through melting and vaporizing phase transitions, reducing the thermal loading of the graphite matrix. The liquid AlSi alloy film covering on the surface prevents diffusion of oxidizing components into the graphite matrix. In addition, Al and Si vapors generated by the vaporization react with the oxidizing components in the boundary layer to reduce their concentrations. Furthermore, the Al₂O₃-SiO₂ glassy molten layer formed by AlSi alloy weakens the mechanical erosion of the gas flow. Thus, the graphite/AlSi dissipative heat-resistant composite throat liner show excellent anti-ablation performance.