ADDITIVELY MANUFACTURED HYBRID THERMAL PROTECTION SYSTEMS FOR SCO2 APPLICATIONS

Combustion impurities in the sCO2 are a concern. With ppm level of impurities, typical of indirect cycles, most sCO2 compatibility studies have shown protective behavior for highly alloyed Fe‐ and Ni‐base structural alloys are compromised. Recent work on Cr- and aluminide diffusion coatings for steel are identified however, these are not applicable for thermal gradient applications. Therefore, protective coatings, especially thermal barrier coatings in a thermal gradient operation, are needed to increase turbomachinery component durability. Traditionally used coatings exhibit spallation due to poor adhesion to the bond coat. This is expected to be accelerated in sCO2 operation due to impurities and carbonization at the bond coat/TBC interface. In phase 1, SOLVE will demonstrate the application of additive manufacturing to engineered surfaces at the bond coat/TBC interfaces, with precise control of surface area and aspect ratios. This will be first demonstration of a hybrid AM+TBC architecture for sCO2 applications. This provides a large range in strain compliance capability, enabling the thermal barrier coating systems to successfully operate in sCO2 environments. With additive manufacturing, unique surface features can be formed on the surface and the proposed innovation will result in a step change in technology of hybrid thermal protection systems for sCO2 applications. One of the extremely exciting aspects of this proposal is the broader impact that advances made in 3D printing for high temperature and corrosion resistant applications of hybrid (AM + TBC) coating architectures. For example, the successful development of hybrid thermal protection systems will find application in the following areas: (1.) Conventional fossil fuel powered utilities. With demands for increasing efficiency high temperature capable TBCs will be very valuable for reduced cooling flow and taking full benefit of additive manufacturing. (2.) Hypersonic vehicle applications – 3D printing can enable very high geometric complexity and provide unique graded functionalities, thus very adaptable to different locations in the hypersonic vehicle design.