Energetic Materials Development at Technanogy Materials Development

Abstract

An energetic material has been routinely manufactured from nano-metric powders of aluminum (Al) and molybdenum trioxide (MoO3). 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 “super-thermites” using n-Al powder in the size range between 30 and 90 nm in diameter (20–60 m2/g, 60–80 wt%Al) and an oxygen to fuel (O/F) mass ratio of 1.4. The burn-rate decreases when the surface area of the MoO3 is decreased from 64 to 40 m2/g, or when O/F is changed from 1.2. Thus, for each average particle diameter, there is an optimum burn-rate at an O/F 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 nano-metric 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-MoO3 can decrease two-fold 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 nano-metric powders and their super-thermite mixes.

Comparison of Performance of Fast‐Reacting Nanothermites and Primary Explosives

“…Content of Al in airtight reservoir does not change during 10 years [40]. Walter et al [43] have published a curve representing the increase of the alumina layer with time, for a sample kept in a non-air-tight clear glass vial. The thickening from 2.1 nm to 2.9 nm has been studied during 4000 h. The curve has a logarithmic shape.…”

Nanomaterials in Pyrotechnics

“…Walker 20 developed a modified sol-gel method for Fe 2 O 3 xerogels. It allows the design and control of the interfacial area between oxidant (iron oxide matrix) and metal-reducing agent.…”

Processing, Application and Characterization of (Ultra)fine and Nanometric Materials in Energetic Compositions

“…Drawbacks are the sensitivity towards spark ignition and their ageing properties [3][4][5]. fine aluminium powder with a metallic oxide (e.g.…”