Characterization of Virgin and Charred PICA Seeded for Remote Recession Measurements

摘要

Phenolic Impregnated Carbon Ablator (PICA) thermal protection material was seeded with tracer materials and used for remote recession measurements while tested in the NASA Langley HYMETS facility. Post-test, the samples were sectioned and characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy and compared to virgin PICA samples. A bulk section of virgin seeded PICA was examined in the axial and radial directions to understand the distribution of seed material and to provide a baseline of comparison to the samples tested in the arcjet Three seeded PICA samples were manufactured using seed material combinations of Al, Si, HfO_2, VB_2, Al2O_3, SiO_2, HfC, TiC, NaCl, and MgCl_2 where the seeds were introduced by infusing the seed materials with the resin solution during the phenolic infusion step or encapsulation of seeds in an epoxy disk that is placed internally in the PICA material. The emission spectroscopy results are reviewed briefly before the material characterization is discussed in detail. One major outcome from this study is that seeding particle diameter is critical and seeds on the order of 1µm are preferred for uniform seeding of the PICA carbon preform during phenolic impregnation.