High Emissivity Protective Cerablak Coatings for Metallic TPS

Space transportation and other vehicles entering the earth?s atmosphere at hypersonic speeds undergo aerodynamic heating which necessitates thermal protection systems (TPS) on exterior surfaces. Future reusable launch vehicles (RLVs) will require TPS durable over several missions with rapid turnaround between each flight. Advanced metallic TPS are under development that utilize a honeycomb structure with thin face sheets (typically 7-10 mils) that are coated to provide high emissivity, oxidation protection, and low catalytic efficiency. Currently-available TPS coatings are not adequate and do not have the durability required for use with RLVs. Thus, a new coating system with suitable and environmentally-friendly formulations are required that meet the basic property requirements and also have the ability to withstand the harsh acoustic and aerodynamic thermal environments during reentry over several missions. Phase I results demonstrated technical feasibility of an innovative approach utilizing a nanocomposite material (Cerablak) that contain carbon as nanosized inclusions to provide emissivity. The coatings are deposited using low-cost, simple, easy-to-apply, and stable formulations. High emissivity properties after heat treatment and excellent protection against oxidation protection were demonstrated. Phase II effort will include further optimization of precursor formulations and coating properties with the primary objective to meet the durability requirements.