Copper alloy rocket engine combustion chamber linings have been found
to deteriorate when exposed to cyclic reducing oxidizing (redox) envir
onments, which are a consequence of the combustion process. The deteri
oration, known as blanching, can be characterized by increased roughne
ss and burn-through sites in the wall of the combustion chamber lining
and can seriously reduce the operational lifetime of the combustion c
hamber. A Cu-30 vol.%Cr coating produced by vacuum plasma spraying was
effective in protecting the copper alloy substrate against blanching.
The coating properties were characterized after cyclic oxidation expo
sure to 650 degrees C in air followed by high pressure hydrogen chargi
ng. When exposed to an oxidizing environment at high temperatures, the
coating formed a protective chromia scale that was substantially unre
duced by high pressure hydrogen.