Whether they are rocket propellants or fireworks, all explosives contain a fuel and an oxidizing agent. Sometimes both are in the same molecule, like in TNT; sometimes the explosive is a mixture, like Thermite.
In mixtures, the smaller the particles, the higher the explosive force. American scientists have reported in the journal Angewandte Chemie a new aerosol spray drying method for the generation of periodate nanoparticles that can be used in the formulation of highly reactive explosives.
Energetic mixtures usually have a higher energy density than explosive materials with both components in a single molecule. However, mixtures generally release the energy more slowly because the reaction partners have to find each other.
Nanoenergetics researchers are attempting to achieve faster and more intensive mixing of the fuel and oxidizing agents by drastically reducing the scale of the distances involved. In most nanoenergetic formulations, nanoaluminum (aluminum nanoparticles) is used as the fuel and metal oxides as the oxidizing agents.
Highly oxidizing compounds with high oxygen content, such as perchlorate are an alternative, but cannot be stored as long, partly because they are very hygroscopic. Perchlorates can also cause health problems and environmental damage. Periodates are possible substitutes. They are minimally toxic and don’t absorb water. However, the production of nanoparticles of periodate salts has proven very difficult.
A team led by Michael R. Zachariah at the University of Maryland has now overcome this problem. Their secret is a simple but versatile aerosol spray drying process. An aqueous solution is continuously atomized to form microdroplets, which give off water as they dry, forming nanoscopic grains of salt.
By using special electron microscopic and mass spectrometric techniques in which the samples can be heated extremely fast, the researchers explored the reaction mechanisms involved.
They discovered that the release of gas-phase oxygen is critical for the ignition and combustion of the periodate formulations. The decomposition of potassium periodate (KIO4) takes place in two steps. First oxygen splits off.
The resulting KIO3 then further decomposes to potassium iodide (KI) and oxygen. “Different from most metal oxide decompositions, the first step of periodate decomposition is exothermic, releasing heat,” explains Zachariah. “This is presumably the reason for the low ignition temperature.”About the Author
Michael Zachariah | Angewandte Chemie
More genes are active in high-performance maize
19.01.2018 | Rheinische Friedrich-Wilhelms-Universität Bonn
How plants see light
19.01.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
19.01.2018 | Materials Sciences
19.01.2018 | Health and Medicine
19.01.2018 | Physics and Astronomy