Highly Stable Carbon Fiber Composite Ablators

Ballistic missile defense (BMD) systems use carbon cloth - phenolic (CCP) resin composite materials as ablative insulators in the inlets and throats of many rocket motor nozzles. However, the reliability of hydrophilic phenolic resin composites is compromised through variations in their moisture content, which is created endogenously and added or lost according to the humidity of the storage environment. Pressure exerted within the composite by the H2O gas can cause delamination and/or pitting during heating, leading to unacceptable nozzle performance. An alternative ablative insulator, carbon-carbon composite (C/C), offers improved dimensional and environmental stability but suffers from high cost and long lead times. In Phase I, TDA prepared and characterized a hydrophobic carbon fiber composite that offers enhanced environmental stability and a very high char yield relative to CCP, yet also reduces cost and lead times relative to C/C. In Phase II, TDA and our partners will scale-up the synthesis of the resin, and prepare coupons for detailed testing, allowing the project team to optimize performance. Tests with a 6-inch diameter rocket motor will conclusively demonstrate performance under the most realistic conditions. This work will lead to an advanced material that will assure the performance of U.S. missile assets.