Robert Hickman

MATERIAL PROPERTIES OF NET SHAPE, VACUUM PLASMA SPRAYED RHENIUM AND TUNGSTEN

The development of materials with unique and improved properties using low cost processes is essential to increase performance and reduce the cost of propulsion systems. Specifically, advancements are needed for non-eroding nozzles in boost and tactical solid rocket motors. These motors operate at very high pressures and temperatures and must survive high thermal stresses with minimal erosion to maintain performance. Recently, innovative Vacuum Plasma Spray (VPS) processes have been demonstrated for fabricating large, net shape, components. VPS W-Re and W-Re-HfC samples were fabricated for characterization and hoop tensile testing. The results are compared to previously tested VPS pure W. Standard metallurgical techniques were used to characterize the effect of processing parameters on the microstructure of the spray formed deposits. Post heat treatments were optimized to further consolidate the material with minimal grain growth. The materials are high density with fine grain structures. Net shape throats were also fabricated and hot fire tested.

Advanced Materials and Processes for Boost Phase Nozzles

The development of materials with unique and improved properties using low cost processes is essential to increase performance and reduce cost of solid rocket motors. Specifically, advancements are needed for boost phase nozzles. These motors operate at very high pressures and temperatures. The nozzle must survive high thermal stresses with minimal erosion to maintain performance. Current R&D is focused on non-eroding throat and nozzle materials such as tungsten (W), tungsten-rhenium (W-Re), tungsten-rhenium-hafnium carbide (W-Re-HfC) alloys, and tantalum carbide (TaC). Innovative Vacuum Plasma Spray (VPS) processes have been developed to fabricate these materials to net shape. Samples were fabricated for characterization and material property testing. Standard metallurgical techniques were used to characterize the effect of processing parameters on the microstructure of the spray formed deposits. Advanced single and 2-piece nozzles have been fabricated and hot fire tested.