Effect of Titanium Compounds on the Ablation Resistance of Polymer Matrix Composites for Aerospace Propulsion

ABSTRACT With the use of high energy propellants, conventional thermal protection system (TPS) materials face difficulty in meeting the stringent performance demands in harsh high‐temperature conditions. This underscores the urgent need for the creation of high‐performance polymer matrix composites suitable for ultra‐high temperature (UHT) ablative environments to meet the requirements of TPSs used in UHT combustion chambers. This study investigates the resistance to ablation in EPDM‐based materials for TPSs reinforced with TiO 2 and TiB 2 fillers. It is found that both TiO 2 and TiB 2 can reduce the rate of ablation for the TPS material. To optimize the design of TiO 2 and TiB 2 fillers, the mechanisms behind their ablation resistance were explored from the standpoint of char layer formation morphology, high‐temperature thermal stability, and carbothermal reduction reactions. The results demonstrate that TiO 2 and TiB 2 enhance the density of the char layer, leading to an improved residue yield of the TPS material under high‐temperature conditions. They also support the development of TiC and SiC within the char layer, with TiC being the initial phase to form, which reinforces the ablation resistance of the TiO 2 ‐ and TiB 2 ‐reinforced TPSs. These reinforced TPS materials show promise for meeting the requirements of TPSs used in UHT combustion chambers. The reinforcement mechanisms provided by TiO 2 and TiB 2 contribute significantly to the development of TPS materials with exceptional ablation resistance, further supporting the establishment of computational models capable of predicting ablation performance.