Ultrafine HfC/TaC for Rocket Thrusters

Liquid rocket engine performance can be dramatically improved by increasing the wall temperatures for operation concurrent with a reduction in the component weight. The bipropellant fuel combustion temperatures are between 3000 "approx" 3500 C. The conventional thrusters and exit nozzles made of niobium alloys have a maximum operating temperature limit of 1600 C. A regenerative cooling technology is normally used to keep the wall temperatures below its limit. This type of cooling is not effective for smaller engines because of the lower propellant flow rate and great wall area/flow rate ratio. The state-of-the-art propulsion systems made of rhenium coated with iridium permit wall temperatures to be as high as 2200 C. Unfortunately, Re-Ir components are heavy and expensive. In this SBIR research program, MMI proposes to develop a lightweight high temperature material, (Hf,Ta)C, through a novel approach. The precursor to (Hf,Ta)C is in a liquid form, which is potentially capable of infiltrating reinforcement materials such as graphite fibers to form composites. The resulting (Hf,Ta)C phase will be nano-crystalline, which will have improved toughness/ductility. In Phase I, efforts will be focused on materials synthesis and consolidation. Composite formation, component fabrication and testing will be pursued in Phase II along with an industrial partner.