Erosion Resistant Thermally Conductive Throat Inserts for Solid Fuel Rockets

Ramjets can increase the range of missiles, because airbreathing propulsion systems pack more energy into each missile by eliminating oxidizer. Boron is frequently added to fuel due to the high energy of combustion. To fully extract energy from combustion, the boron trioxide product must be condensed. To condense boron trioxide, heat must be conducted away from the nozzle of the ramjet. To efficiently conduct heat through the throat, the nozzle must be made of highly thermally conductive materials. The throat must also be resistant to erosion caused by impinging alumina particles, byproducts of the reaction of aluminum additives in the fuel. Graphite and carbon-carbon, common ramjet nozzle materials, erode when used with aluminized fuels. Tungsten liners prevent nozzle erosion from aluminized fuels. The ideal throat material must have a high emissivity to absorb heat by radiative heat transfer. This phase I study will develop ramjet throats with high thermal conductivities. Two manufacturing methods for fabricating the refractory liners will be investigated. The liner thermal conductivity and the emissivity will be measured and used for thermal and structural models to determine the effectiveness of the liner and support combination. Finally, liners and supports will be produced for testing and evaluation.