Experimental study on charring layer surface phases of EPDM insulator in elevated temperature

A surface-impacting device was designed to study the phases of the charring layer surface of EPDM insulation in the ablation process and the structures of charrig layes resist the effect of collision under elevated temperatures.By using this device in the gas produced from composite propellant containing 5% aluminum, the experiment was successfully carried out and the morphology of the impacted charring layer surface was clearly observed.The results show that under the experimental conditions, the charring layer surface of the tested EPDM is primarily in solid state, without some thick liquid layer existing.Under elevated temperatures, the charring layer surface impacted would be cracked, which then affects its ablation property.The experimental results may be useful for further research on ablation mechanism of EPDM insulator.