This proposal addresses NASA's need for improved TPS materials. The incumbent CEV heatshield TPS for Orion's Block II lunar return is PICA, a low-density carbon fiber infiltrated with phenolic resin. Variants of PICA with improved thermomechanical properties would benefit future missions. This effort will create a series of "mid-density" ablative materials to fill the gap between low-density PICA and high-density Carbon-Carbon. Touchstone's carbon foam (CFOAM
REG) has excellent thermomechanical properties, can be tailored to a range of densities (12 to 95 lbs/cu-ft), and has an open-cell structure allowing infiltration of high-temperature materials. Aspen Aerogels recently completed a Phase II subcontract with Touchstone demonstrating the capability of fully infiltrating CFOAM
REG with phloroglucinol-furfuraldehyde carbon aerogels with chemistry similar to PICA's. Phase I will use carbon aerogel infiltration in CFOAM
REG samples of 3 densities from 17 to 35 lb/cu-ft to be calcined at Touchstone to carbonize the aerogel, creating a mass of amorphous carbon within the pore structure. Filling CFOAM
REG pores with pure carbon yields an inherent reduction in the TPS radiant heat transfer. Fully carbonized samples will be re-infiltrated with PICA phenolic resin, and sample characterization will be conducted via SEM to demonstrate the capability of producing small-scale Carbon Foam-Aerogel/Phenolic composites at various densities. At the end of Phase I, the TRL will be 3-4 and then 4-5 by the conclusion of Phase II.
More »