Synthesis and Characterization of Lead-Free Primary Explosives

This project is planned to be performed under the supervision of Prof. Thomas M. Klapötke (Ludwigs- Maximilians-Universität München, Germany), who is one of the leading researchers in the field of energetic compounds (inorganic chemistry). Primary explosives are inherent parts of ammunition and blasting initiators. Lead azide and lead styphnate are the most common primary explosives. Unfortunately, when initiated, these lead containing primers decompose and form lead-containing aerosols, which can be inhaled. These particles cause chronic lead poisoning in case of regular exposure. Population groups affected by this pollution are e.g. marksmen, police officers, soldiers, and tunnel miners. Recent studies on the lead content of the blood of people exposed to these lead aerosols found levels 10 times as high as health limits. Therefore, there is a real need for "green explosives", replacing lead compounds in primers. In principle, a primary explosive is a compound that is sensitive to heat, shock, friction, or electric sparks. When initiated, the primer decomposes and produces a tremendous amount of heat and/or shock. Thus, the primary explosive transmits the detonation to the secondary explosive, which is less sensitive. The secondary explosive serves as the propellant of the bullet (in case of ammunition) or transmits the detonation to the main blasting agent (in case of blasting). The search for lead-free primary explosives has been going on for more than two decades. Aim of this project is to investigate two classes of compounds with regard to their properties and their applicability as lead-free primary explosives in ammunition and blasting initiators. In particular, two nitrogen rich anions, 5,5`-azotetrazolate (containing 85% N) and 5-nitrotetrazolate (containing 61% N) will be precipitated or crystallized with (mostly) nonpoisonous transition metal cations. The six to ten new compounds will be synthesized and investigated using modern analytical techniques like X-Ray diffraction, MS, NMR, FT-Raman, and FT-IR spectroscopy, as well as DSC and RADEX thermal analyses and methods for the characterization of the performance of an explosive, like drophammer tests, bulging of a lead-block (Trauzl-Test), spark spraying, the friction test, the electrostatic test, and the steel shell (Koenen) test in a Scientific Detonation Chamber. All these methods will be available and applied during the postdoctoral research work. The implementation of nontoxic primary explosives would be a further step towards the removal of lead from applications in human surroundings, a trend that has been going on for decades.