SICR

Shock-Induced Chemical Reactions (SICR) in Powder Mixtures:

Shock compaction of energetic powder mixtures to synthesize new materials is one of the oldest material processing techniques and has been studied extensively by several researchers over the past five decades. The high temperatures caused by the shock deformation are sufficient to trigger reactions between the powder reactants, resulting in the desired compounds.

Our goal is to simulate this complex chemo-thermo-mechanical phenomenon using our meshless code based on SPH.

Here are some interesting animations of the simulations of compaction and reaction processes. As a model reaction, formation of Niobium Silicide from the powders of Niobium and Silicon is considered in our work.

The figure above shows a mixture of Niobium (light grey) and Silicon (dark grey) powder particles kept between two inert steel plates. The left wall is given an impact velocity. The particles are assumed to be circular in shape and equally distributed in size. The right wall is modelled as a non-reflecting boundary, so that the incident shock never reflects back in the mixture. The particles are not allowed to cross the top and bottom surfaces so that the system is periodic in y-direction. Mathematical description of these boundary conditions can be found in Benson (2001).

In the inset of the figure, SPH discretization of a Silicon particle is shown.

Results:

Overall mass fractions of the Niobium, Silicon and Niobium Silicide at 1250 m/s impact velocity:

The figure below shows contour plots of product mass fractions at different instances for an impact velocity of 1250 m/s.

Below, animations of SICR at 1500, 1250 and 1000 m/s, respectively, are shown. Regions in red color indicate fully reacted regions. Partially reacted regions are colored from blue to orange in the order of increasing mass fraction of the product.

Animation of SICR at 1500 m/s impact velocity.

Animation of SICR at 1250 m/s impact velocity.

Animation of SICR at 1000 m/s impact velocity.