Ablation Characteristic of 3D C/SiC Composite Nozzle in a Small Solid Rocket Motor

Ablation properties of a 3D C/SiC composite nozzle were investigated by using hot-firing test in a small solid propellant rocket motor.Ablation mechanisms of the C/SiC composites and effects of the combustion gases parameters were discussed.The results show that the linear ablation rate at the throat of the composite nozzle is 0.128±0.088mm/s,and the mass ablation rate is 0.166kg/(m~2.s). Ablation behavior for the 3D C/SiC composite shows a nonuniform process,which is directly affected by the compositions,temperature,pressure and the velocity of combustion gases.The ablation in the divergent section,convergent section and the regions near the throat grows severe by degrees. Ablation mechanisms of C/SiC composite are the cooperation of thermo-physical ablation,thermo- chemical ablation and thermo-mechanical erosion,which involve the decomposition of the SiC,oxidation of the SiC and carbon fiber,as well as chemical and mechanical erosion by Al_2O_3 slags and particles, respectively.