SBIR/STTR Award attributes
The innovation proposed here is a novel carbon-carbon composite (CCC) manufacturing method based on polymer infusion and polymerization (PIP) using a novel precursor polymer with exceptionally high char yields (>80 %). This results in a material that has the promise of excellent quality and mechanical properties, while offering the breakthrough advantages of (1) greatly reduced or eliminated need for backfill infusions (2) greatly reduced cycle time (3) excellent fiber wetout and microstructure after carbonization (4) ambient-pressure processing (i.e. no isostatic press needed) (5) inexpensive precursor resin These advances to the state of the art are critical to US competitiveness and national security, as CCC structures for hypersonic thermal protection systems (TPS) are one of the most costly and schedule-driving factors in achieving parity with our adversaries. Manufacturing of CCC structures is not only time consuming and costly, but also results in relatively poor mechanical properties, especially in the interlaminar properties, and these problems increase exponentially with the thickness of the structure. In large part this is due to the fact that during pyrolysis from e.g. a carbon-phenolic (e.g, ACC-6 resin) composite to carbon-carbon, a large percentage of mass is lost to pyrolysis products, resulting in high porosity and poor mechanical properties. This is partially addressed by re-infusion and re-pyrolysis (either with liquid or gaseous sources of additional carbon), but these processes are diffusion-dominated, and their effectiveness (particularly reproducibly) rapidly declines as structures are made thicker. This is a major problem when structural thickness must be increased due to reinforcements, stiffener attachments, interfaces with underlying structures, etc. As is evident from the CCC literature, our adversaries (particularly China) have invested significant time and resources into the processing of CCCs from pitches and phenolics. The path to quickly attaining parity with our adversaries likely won’t come from retracing their previous developments, rather a paradigm shift is required. The path to modernization of US defenses is and has always been through the development of materials strategically tailored for leap ahead capabilities, as opposed to constraining engineering solutions to “off the shelf” decades-old materials. With further development, the technology proposed herein could allow rapid manufacturing of thick carbon-carbon structures. The manufacturing innovations include a precursor resin improvement with the overall goal of reducing manufacturing times of thick laminates from months to weeks. The fast-manufacturing capabilities potentially provided by this strategy must be explored as it is a feasible route to manufacturing a stockpile of TPS materials, in alignment with the DoD’s timeline.
