Characterization and Scaleup of High Temperature Oxidation-Resistant Coatings for Carbon/Carbon Composites

Hypersonic flight performance of a lifting body vehicle design is improved significantly by the drag reduction achieved when nose and wing leading edges are sharp and shape-stable under all flight conditions. Silicon carbide (SiC) is an established oxidation protection coating for carbon/carbon (C/C) composites. When exposed to an oxygen-containing atmosphere, SiC forms a stable surface oxide layer of silicon dioxide (SiO2) that provides oxidation protection up to 1600°C, but beyond that temperature it suffers from degradation due to active oxidation. For operation above 1600°C, Ultramet has developed and successfully demonstrated a hafnium carbide-silicon carbide (HfC-SiC) coating, designated Ultra2000, as a replacement for SiC on C/C structures. The proposed project will seek to fully understand the characteristics of the coating such as processing variability, composition, and microstructure and how those properties, including evolved Hf-Si oxide composition, are affected by the high heat flux environment and in turn how they influence high heat flux performance. The material characterization performed in this project will supplement ongoing Ultra2000-coated C/C material development with a fundamental understanding that will support faster progression of the coating system TRL toward program insertion.