Catalytic Ignition System for Advanced Boost-Phase Intercept Applications

Phase III IHPRPT goals call for a 70% increase in density Isp for monopropellant systems. Advanced HAN-based monopropellants such as AF-m315 have the potential not only to exceed this goal, but also to exceed the density Isp of NTO/MMH. But before suchpropellants can be commercialized, a reliable ignition system must be developed. While a heated bed of Shell-405 catalyst can ignite the propellant, the catalyst support is unable to survive for more than a few seconds. A reliable catalytic ignitionsystem is thus a required, enabling technology. Development of such a catalyst will enable performance increases well beyond the IHPRPT goals. By some estimates, the performance increase can be as high as 78% or even 80%, and would hence be ideal for themost demanding applications. Ultramet has completed several projects directed toward the development of a catalytic ignition system for HAN-based monopropellants, and many key developments have been made. Ultramet has previously demonstrated roomtemperature exothermic activity (<25 C onset temperature) with several different catalyst/propellant combinations, and extremely fast activity in spot plate testing with others. The most reactive catalysts at room temperature were those that did notutilize a platinum group metal. Ultramet has also identified and/or synthesized high surface area, high melting point, oxidation-resistant support materials with surface areas in excess of 2800 m2/cm3 and melting points in excess of 2750 C. This comparesvery favorably with the support used for Shell-405, which has a surface area of only ~800 m2/cm3 and decomposes to alpha-Al2O3 at ~1100 C. In this project, Ultramet will take the knowledge gained in the previous work and combine it into a catalyst/supportcombination wherein the support is catalytically active and can assist in decomposing the propellant if/when the overlying catalyst (e.g. iridium) is chemically etched and removed from the support. The goal will be to reliably ignite HAN-basedmonopropellants at low temperature using a catalyst that can tolerate prolonged time at operating temperature. The proposed technology will make the use of advanced, environmentally friendly, high-performance monopropellants a reality. This will not onlyeliminate the use of toxic propellants such as hydrazine, but also allow the use of propellant blends that promise a dramatic increase in density specific impulse relative to hydrazine.