Synergetic effect of aramid fiber and carbon fiber to enhance ablative resistance of EPDM-based insulators via constructing high-strength char layer

Aramid fiber has been commonly used in EPDM-based insulators to enhance ablative resistance as the char layer skeleton, due to its good flexibility and low thermal conductivity. However, its thermal stability restricts the improvement of ablative performance to meet the growing requirements of Solid Rocket Motors. In this work, hybrid fiber network was constructed in char layer via the combination of aramid fiber (AF) and carbon fiber (CF), due to high thermal stability of CF. The results showed that linear ablation rate displayed a valley-shaped change as the CF ratio increases, and best ablative performance was obtained at the 1:1 ratio with the linear ablation rate reduced to 0.0604 mm/s, which was 31% lower than that of the insulator filled with only AF. Furthermore, the ablation mechanism was studied based on the evolution of char layer structure and the formation of char layer with CF shielded at surface and AF consolidated inside could account for the synergetic effect on ablation resistance.

Automated summary

A hybrid fiber network was constructed in the char layer combining aramid fiber (AF) and carbon fiber (CF) in order to improve the ablative performance of EPDM-based insulators for Solid Rocket Motors. The best ablative performance was achieved at a 1:1 ratio of AF and CF, resulting in a 31% reduction in linear ablation rate compared to insulators filled with only AF. The formation of char layer with CF shielded at surface and AF consolidated inside was found to have a synergetic effect on ablation resistance.