A Modular In-Situ Curing Apparatus for Thermoset Resin Mixtures Applied as Thermal Protection Systems

Future human extraterrestrial missions will require export and landing of countless payloads on the lunar and Martian surfaces. Such a quantity and rate of payload delivery will require cost-effective and rapid manufacturing of many large Thermal Protection Systems (TPS). IOS proposes to develop a modular system for in-situ bonding and curing of thermoset resin to the spacecraft structure to facilitate automated manufacturing of TPS. This system will be compatible with additive manufacturing techniques, high-temperature thermoset resins, and composite substrates currently in use and under development by NASA, SpaceX, and others. Our system, combing in-line IR gelation of the resin extrudate and in-situ c-staging, will eliminate the need for large ovens or autoclaves. By leveraging advances in out of autoclave curing methods our system will enable curing of additively manufactured high temperature thermoset resin based TPS in-situ. An infrared heat source mounted directly on the print head will rapidly gel the extrudate as it leaves the nozzle, enabling multi-layer printing. Upon completion of the printing process, a modular system of conductive heat blankets, conforming to the surface contours of the structure will control final cure of the thermoset. The system will measure the temperature of the resin and provide feedback control and log thermal history during curing. In-line surface activation with a corona generator will ensure strong bonding to the underlying substrate and at layer interfaces.Validation of the system will be performed by measuring the degree of cure of in-situ cured samples and measurement of bond strength. We anticipate in-situ cured samples to achieve a high degree of cure, char yield, glass transition temperature, and bond strength, comparable to traditionally cured resins. Target end points for Phase I work are deviation of no more than 10% between in-situ cured and control cured resins.