Manufacturing and Performance of Nanometric Al/MoO3 Energetic Materials
2007; American Institute of Aeronautics and Astronautics; Volume: 23; Issue: 4 Linguagem: Inglês
10.2514/1.25461
ISSN1533-3876
AutoresK.C. Walter, David R. Pesiri, Dennis Wilson,
Tópico(s)Rocket and propulsion systems research
ResumoNanometric powders of aluminum (Al) and molybdenum trioxide (MoO 3 ) have been combined to create an inorganic energetic material. When optimized, the burn rate of these materials (∼400 m/s) exceeds that of conventional thermites (based on micron-sized powders), but is less than that of conventional explosives. Similar burn rates around 350 m/s are measured for these superthermites using n-Al powder in the size range between 30 and 90 nm in diameter (20-60 m 2 /g, 60-80 wt % Al) and an oxygen-to-fuel mass ratio of 1.4. The burn rate decreases when the surface area of the MoO 3 is decreased from 64 to 40 m 2 /g, or when oxygen to fuel is changed from 1.2. Thus, for each average particle diameter, there is an optimum burn rate at an oxygen-to-fuel ratio that depends on the wt % Al present in the material and the particle size distribution of the powder. The burn rate is dependent on several materials and processing factors such as the quality of the nanometric ingredients, the processing method, and exposure to air and light, so the effect of aging and environmental exposure on the individual ingredients has been investigated. The results of this powder aging study suggests that the surface area of n-MoO 3 can decrease twofold within 10-12 days, and the Al-metal content in n-Al can decrease as much as 50% over two years. Adequate handling and storage procedures must therefore be followed for the effective use of nanometric powders and their superthermite mixes.
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