Vacuum Infusion Process Development for Conformal Ablative Thermal Protection System Materials

Abstract

Conformal ablators are low density composite materials comprised of a flexible fibrous substrate and polymer matrix. These materials are fabricated to near net shape by placing the substrate in a rigid, matched mold and infusing with liquid resin in an open, vacuumassisted immersion process. This process, originally developed for older rigid substrate ablators such as PICA, wastes a substantial amount of resin. In this work, a vacuum infusion process -a type of liquid composite molding where resin is directly injected into a closed mold under vacuum -is advanced for conformal ablators. The process reduces waste over the state-of-the-art technique and may eliminate the need for an atmosphere-controlled oven. Small, flat samples of Conformal Phenolic Impregnated Carbon Ablator are infused using the new approach and subjected to a range of curing configurations and conditions. Resulting materials are inspected for quality and compared to material produced using the standard process. Density, resin mass fraction and char yield are measured. Lessons learned inform subsequent plans for process scale up.