Reactive metal wires in a fuel oxidizer mixture

[hilbert2]

TL;DR Summary

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.

 

[jbsteele]

So, the answer is that it is possible to accelerate the combustion rate of a slow burning pyrotechnic mixture by introducing thin wires of reactive metals such as magnesium or magnesium/aluminum alloy. It is important to note, however, that these mixtures can be hazardous and should only be handled by experts.