IMPROVING THE EFFICACY & ECONOMICS OF CANDIDATE HYPERSONIC MATERIALS
Abstract
The thermal mismatch between the structure (C/C or W) and the discrete coating layers provides a potential failure mode (~1000 ??C Ir ) for coating in highly transient thermal loading seen in rocket motor and hypersonic aerosurfaces. The thermal expansion and modulus mismatch is significant between a C/C or W leading edge and a protective coating such as and Ir. The proposed use of Re as a matrix transition layer provides a coefficient of thermal expansion intermediate to that of C/C or W and outer layers of Ir. Additionally, the another primary function of the Re matrix transition layer is to enable subsequent molten salt electrodeposition of the critical oxygen diffusion barrier layer (Ir). Re enhances the wettability of molten salt electrolyte and increases the bond strength of the electrodeposited Ir layer. The Re matrix transition layer allows for a chemically bonded to the C/C or W structure, as opposed to a less adherent mechanical bond seen through other deposition processes. There is a lack of mutual solubility on the C-Re phase diagram and no Re carbides exist in equilibrium at atmospheric pressure, making the choice of Re ideal from a chemical point of view.. Additionally, there is a large range of mutual solubility on the W-Re phase diagram that may be useful as a diffusional bond between W and Re foil. In this program, the investigators will study the deposition of Re onto C/C or W substrates via electrodeposition, and subsequent processing of Ir and Ir-oxide nanoceramics poders, graded out to a low-emissivity surface layer that would be ideal for re-radiation of high heat flux inputs seen during hypersonic flight.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 26, 2018
- Source ID
- N000141812516
Entities
People
- Michael Brupbacher
Organizations
- Johns Hopkins University
- Office of Naval Research
- United States Navy