(399a) Role of Nano-Particles in Energetic Materials Development

If the solid-solid reaction is strongly exothermic a rich spectrum of completely new phenomena can occur. Many exothermic solid-solid reactions as, for example, aluminothermic operations and intermetallic processes are far more energetic than energetic substances which can detonate, as for instance TNT or RDX Therefore, some time ago we asked an interesting question: Is it possible to find conditions under which the solid-solid reactions listed above will detonate ? The rapid and violent form of energy release, called detonation, is caused by a shock wave propagating into the energetic material. This shock heats the material by compressing it and thus triggering a chemical reaction. Eventually a balance is attained such that the chemical reaction supports the shock. In this process material is consumed several order of magnitude (103-108) faster than in a flame, making detonation easily distinguishable from other energy release processes. For example, a good solid explosive converts energy at a rate 1010 W/cm2 in the detonation front. For perspective, this is hundred times higher energy flux than regular laser or energy beam. Our analysis of the problem reveals that four different regimes of operation can exist: kinetic, slow SHS deflagration, fast SHS deflagration and SHS detonation. The kinetic regime is extremely slow and is important only in corrosion science. A typical SHS reaction, which have been studied so far is of the type of slow SHS deflagration. If mixture of ultra-fine particles is thermally initiated, the velocity of propagation are in the range of 10-800m/s and we refer to this regime as a fast deflagration SHS. However, if such a mixture of powders is initiated by a shock wave a fast detonation regime can result with velocities 4-10km/s. We call this regime a SHS detonation regime. The lecture will discuss following problems: ? reactivity and shear stress ? stored energy in nano-particles ? reaction and role of diffusion ? ultra-fine particles and detonation ? potential for the new type of explosives ? nano-sized slurries in hydrocarbons ? amorphous carbon as fuel