Kate RHOADS, Kristen PRICE, Stefan LOEHLE, Savio POOVATHINGAL, Alexandre MARTIN
DOI Number: N/A
Conference number: HiSST-2025-307
Ablative thermal protection systems (TPS) are used during atmospheric entry to mitigate thermal energy transport to the substructure of spacecraft through material degradation. In order to better understand in-depth material changes due to volumetric ablation, previously tested samples were re-exposed to a pure oxygen environment in the High Enthalpy Low-Cost Multi-Use Torch (HELMUT) facility at the University of Kentucky. Additionally, PICA samples were tested to investigate the impact phenolic resin has on the material response. Scanning electron microscopy (SEM) was conducted on disconnected fibers that remained on the samples after flow exposure to investigate in-depth fiber and binder pitting. Material response across test campaigns was compared to evaluate changes in structural integrity caused by in-depth oxidation, which is suspected to affect spallation behavior. Re-exposure produced higher percent volume loss, greater percent mass loss, and a reduction in density. PICA samples produced a negligible fiber layer, and a lower percent volume loss. These findings indicate that FiberForm tested in the HELMUT facility could be operating in a reaction-limited regime, with substantial oxygen penetration beneath the surface. This methodology also establishes a framework for providing degree of char estimates for material response models, and highlights the role phenolic resin has on structural integrity.