Charring layer structure character of EPDM insulator in simplex thermo-chemical ablation environment

The ablation test of EPDM insulator was carried out with a test device at low gas speed(0.48 m/s)and the composite propellant contains only 1 percent aluminum. A special feature of the test is simplex thermo-chemical ablation. The structure character of charring layer was analyzed by using SEM. The results show that grain substance is distributed evenly on charring layer surface, the back has a meshy structure, and the profile has the feature that upper part is more compact while middle part and lower part are porous. A comparison is made of the charring layer structure character in three different operational environment. In severe ablation environment, the upper compact layer is very thin. The test results are important to ablation mechanism research and ablation modeling of EPDM insulator.