NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Diffusion mechanisms in Ir-coated Re for high-temperature, radiation-cooled rocket thrustersMaterials used for radiation-cooled rocket thrusters must be capable of surviving under extreme conditions of high temperatures and oxidizing environments. Thruster chambers were developed using chemical-vapor-deposited (CVD) Re coated with CVD Ir on the inside surface which is exposed to hot combustion gases. Ir serves as an oxidation barrier protecting the Re which maintains structural integrity at high temperatures. In order to predict and extend the performance limits of these Ir-coated Re thrusters, the diffusion kinetics of CVD materials at temperature are studied. Thruster end ring sections were examined using electron microprobe analysis both before and after exposure to high temperature vacuum environments. The resulting elemental maps for Re, Ir, and Mo in the near-surface region allow identification of diffusion mechanisms operating at these temperatures. Line scans for Ir and Re were fit using a diffusion model to extract relevant diffusion constants. The fastest diffusion process is seen to be grain boundary diffusion with Re diffusing down grain boundaries in the Ir overlayer. The measured dependence of the diffusion rate on temperature will allow prediction of operating lifetimes for these thrusters.
Document ID
19910059534
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Hamilton, J. C.
(Sandia National Labs. Livermore, CA, United States)
Yang, N. Y. C.
(Sandia National Labs. Livermore, CA, United States)
Clift, W. M.
(Sandia National Labs. Livermore, CA, United States)
Boehme, D. R.
(Sandia National Labs. Livermore, CA, United States)
Mccarty, K. F.
(Sandia National Laboratories Livermore, CA, United States)
Date Acquired
August 15, 2013
Publication Date
June 1, 1991
Subject Category
Spacecraft Propulsion And Power
Report/Patent Number
AIAA PAPER 91-2215
Accession Number
91A44157
Funding Number(s)
CONTRACT_GRANT: NAS3-25646
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available