Composite Hot Structures with Oxidation Protection

Hot structures have been developed for a variety of advanced vehicles including the X-43A, X 37, Space Shuttle, and Advanced Hypersonic Weapon. Most of the hot structure and leading edge components on these vehicles employed composites, such as the carbon/carbon (C/C), which have significant advantages over metallic solutions. Advantages include high specific strengths; high temperature capability without the need for active cooling; and high fracture toughness. However, since C/C offers no self-protection in oxidative environments, coatings are required. Hot structures are preferred over tiles and blanket thermal protection systems, because they are more durable, easier to inspect and require less maintenance and repair. To enable future hypersonic defense, cost effective, environmentally durable and manufacturable hot structures are critical. Plasma spray deposition of SiC-based coatings is beneficial for large hot structure components, not amenable to traditional SiC application methods. Furthermore, plasma spray deposition is an effective repair technique. During the Phase I, multiple SiC-based materials protected C/C from oxidation/erosion in high heat flux testing. Building on Phase I success, the technical objective of the Phase II effort is to optimize plasma sprayed SiC-based coatings for oxidation protection of C/C in hot structure applications >3000ºF and compare to other approaches. Approved for Public Release | 18-MDA-9817 (23 Oct 18)