Reactive metal wires in a fuel oxidizer mixture

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The discussion centers on the potential effects of incorporating thin magnesium wires into a slow-burning pyrotechnic mixture, specifically a combination of potassium nitrate (KNO3) and powdered charcoal. It is suggested that the presence of magnesium, known for its rapid combustion in oxidizer mixtures, could significantly accelerate the ignition and combustion rate of the KNO3-charcoal mix. The idea is to create multiple ignition points to enhance the overall combustion speed. While this presents an intriguing combustion science problem, there are concerns regarding safety, as such mixtures can detonate and produce pressure waves even when unconfined. The conversation emphasizes caution and discourages non-experts from experimenting with these materials.

Nov 8, 2022

#1

hilbert2

Science Advisor

Insights Author

TL;DR: Small mass-% of reactive metal (magnesium or similar) wires being able to accelerate the combustion of a pyrotechnic mixture.

Suppose there's some slow burning pyrotechnic mixture like KNO##_3## with powdered charcoal, and several really thin threads/wires of magnesium metal (or zirconium or magnesium/aluminum alloy) are made go through a pile of that mixture. Now I would guess that because a mixture of finely powdered magnesium with oxidizers burns with a really fast "flash", and is used in fireworks for that purpose, the effect of even a small amount of magnesium wires through that kind of KNO##_3##-C mixture would be to make it combust much faster with the fire propagating more rapidly on the surface of those metal wires. So the idea is to make the slow pyrotechnic mix ignite at several points at the same time to accelerate the combustion rate. I'm not sure if this has any real application unless those reactive metals become much more expensive for some reason, but it's a bit interesting as a combustion science problem.

I haven't been risking playing with that kind of mixes after teenage years anymore, but I have been working in a fire safety / combustion project some years ago. Definitely not recommending this as an experiment for non-scientists, because those "flash" pyrotechnic mixtures can actually detonate with a pressure wave even when unconfined, if a large enough pile of them is ignited.