Infiltration of Carbon Foam for Mid-Density Ablative Thermal Protection Systems

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 (CFOAMREG) 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 CFOAMREG with phloroglucinol-furfuraldehyde carbon aerogels with chemistry similar to PICA's. Phase I will use carbon aerogel infiltration in CFOAMREG 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 CFOAMREG 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.