Abstract
Pratt & Whitney's upper stage rocket engine development program, designated "RL60", has incorporated cold-sprayed copper to improve the design and function of this new engine. Combustion chamber designs contain two stainless steel manifolds connected by a series of copper tubes. The manifold where the hydrogen fuel exits is located near the injector face. The combustion gases from the injector would cause over-heating of this manifold. Thick copper application was needed to actively cool this manifold by conducting the cold temperatures from the hydrogen fuel inside the copper tubes. Plating copper greater than 0.050-inch thick resulted in poor adhesion following a subsequent braze cycle and required 2 weeks to plate. Cold sprayed copper was attempted which has surpassed plated copper in its ability to adhere through this braze cycle and can be applied in a few hours. In addition, the hazardous chemicals associated with copper plating have now been eliminated.
