General Properties of Nanomaterials

Some important general properties of nano-energetic materials (this term refers to nanoparticles of explosives, oxidizers and fuels either in free flowing or encapsulated form) are  

1) The melting temperature of a nanoparticle dramatically decreases and in some cases, it may be nearly 300 k lower than for bulk material [101]. 

3) The activation energy of NMs being very small compared with bulk materials, makes them very energetically favored. Thus oxidation becomes relatively easier at the nanolevel compared with the microlevel. Similarly, ignition delay of metallic nanoparticles is expected to be several times smaller than the conventional particles. 

4) Thermal conductivity of nano-metal powders (similar to n-Al powder) is, in general, higher compared with micron-sized metal powders. This can increase the energy transfer in the sub-surface region as well as alter the burn-rate characteristics and minimize the incomplete combustion of metal powders. 

In a nutshell, the performance of weapons and munitions increases with the use of nanosized particles because of the increased surface area and enhanced heat transfer resulting in reduced ignition delay, burn time, improved mechanical properties and high density-specific impulse. Further, formulations based on micron-sized materials with a wide distribution suffer from defects such as slow energy release, incomplete combustion and inability to support rapid combustion which can be overcome with the use of nanoparticles or nanomaterials [102]. 

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