Security

 

In this field the CNST works in collaboration with forensic science and DSTO investigating areas such as:                                                                            

  • Highly sensitive chemical & bio sensors
  • Fingerprinting using quantum dots
  • Examining the structure of explosive molecules
  • Human identification using microfluidics

 

Energetic materials are explored within the security area of CNST research. Such structures are defined as a class of material with a high amount of stored chemical energy that can be released. These have novel applications through a range of areas including munitions, detection and neutralisation of explosives and the mining sector. The CNST focusses on exploring the chemistry of nano-energetic materials and examining the structure of these explosive molecules.

Porous Silicon (pSi)

Porous silicon energetic materials are a new class of explosives called “nano-energetics.” They work because of an extremely intimate mixture between the fuel (silicon) and oxidizing agent – reactions that would otherwise not happen now occur explosively. The advantage of these materials is the way that the porous silicon can be prepared using standard techniques available to the electronics industry, and the way that the performance of the material can be tuned by controlling the preparation conditions.

 

pSi energetic material initiated by a spark

Using certain acids and a controlled electrical current, standard silicon wafers can be etched with pores as small as 3 nanometres (3 millionths of a millimetre), in layers up to 100 microns. The surface area of these materials is very high – over 800 m2 per gram. Oxidizing agents are impregnated into these pores and the material is initiated with a spark, impact or high energy laser. The resulting reactions generate temperatures up to 1200 oC and are able to perform useful work. Reaction velocities of the burning flame front exceed 500 m/s.

pSi energetic material initiated by laser pulse

 

The aim of this project is to investigate and characterise these materials, using techniques such as high speed video recording, calorimetry, and electron microscopy. As a result of these investigations, research has determined that porous silicon can deflagrate (i.e. burn explosively) but cannot detonate. Results also indicate the pSi is sensitive to impact, friction, flame and shock.