High Strength, Nano-Grained Tungsten for Zero-Erosion Nozzle Throat Inserts

Boost phase intercept missiles must be capable of rapidly and accurately intercepting a target. The solid rocket motors needed to achieve intercept during the boost phase require aluminized propellants operating at very high pressures to obtain thenecessary high thrust levels. This requirement presents a severe operational environment with nozzle throat temperatures exceeding 5000F. Throat inserts capable of operating in such an environment must aslo be non-eroding such that the thrust vector ofthe interceptor missile is very predictable, and thus more accurate. This Phase I program will demonstrate a nanograined tungsten material fabricated by chemical vapor deposition that exhibits very high strengths and ultra-high temperature stability, andthus is capable of operating under the extreme thermal stresses imposed during firing. Mechanical and thermal properties will be measured at both ambient and elevated temperatures such that a low cost/low risk fabrication approach can be determined.High strength, nano-grained tungsten has been identified as a potential candidate material for non-eroding throat inserts in solid rocket motors. Performance and/or cost benefits from such material insertion can be realized across a range of boost andtactical missile systems. A zero erosion nozzle throat insert has been recognized as one of the necessary technological advances to meet the goals of the DoD Integrated High Payoff Rocket Propulsion Technology (IHPRPT) program.