Evaluation of Reusable Thermal Protection System Materials Using a High-Velocity Oxygen Fuel Torch

We studied a candidate TPS (thermal protection system) material for reusable re-entry space vehicle applications. The material was based on a high-temperature-resistant material called Cerakwool. A total of six specimens were fabricated with substrate densities of 0.45 g/cm³, 0.40 g/cm³, and 0.35 g/cm³, with two specimens for each density. All specimens were coated with high-emissivity TUFI (toughened unpiece fibrous insulation), with coating thicknesses ranging from 445 to 1606 µm. The specimens were tested using an HVOF (high-velocity oxygen fuel) material ablation test facility. For each density specimen pair, one specimen was tested at 1 MW/m² and the remaining one was tested at 0.65 MW/m². The average stagnation point temperature for specimens tested at 1 MW/m² was ~893 °C, approximately 200 °C higher than those tested at 0.65 MW/m². This suggests a ~200 °C increase in stagnation point temperature for a 0.35 MW/m² rise in incident heat flux. During the tests, internal temperatures were measured at three locations. For all tested specimens, regardless of heat flux test conditions and density, the temperature at ~40 mm from each specimen's stagnation point remained around or below 50 °C, well within the 180 °C design limit set for the TPS back face temperature. Post-test visual inspections revealed no signs of ablation or internal damage, confirming the material's reusability.