A crackle challenge

All Recipes and Chemistry!

Moderators: richardh08, Boophoenix, Lloyd

Post Reply
User avatar
richardh08
Site Admin
Posts: 2226
Joined: Wed Aug 07, 2013 1:54 pm
Location: Bedfordshire

A crackle challenge

Post by richardh08 »

The crackle topic has gone very quiet as of late, while we wait for independent evaluation of our latest formulation.

At some point during our research into the topic, Ken and I set ourselves the target of finding a cheap, heavy-metal-free and easy to manufacture crackle formulation. We believe we have succeeded, but we need to wait for confirmation.

In the meantime, I'm getting bored.

Conventionally, everyone 'knows' that crackle compositions must a) contain lead or bismuth compounds, b) nitrocellulose and c) magnesium-aluminium alloy. We (and the Chinese) have shown that both a) and b) are false.

I'm a simple-minded person, so the challenge that I am setting to myself, and anyone else who cares to take it up, is to find an even simpler formulation. The simplest effective composition that Ken and I know of contains copper oxide, magnesium and aluminium (either alloyed or as separate elements) and an organic binder. Can this be improved on?

The requirements are severe: I'm requiring that that the formulation should be even simpler, and that it should contain no esoteric, hard to obtain or expensive ingredients. It needs to show the classic characteristics of ignition-delay-report, and must be reliable in its performance.

Thoughts, anyone?
Even when I'm wrong, I'm convincing.
sambo
Posts: 957
Joined: Sat May 16, 2015 6:04 pm

Re: A crackle challenge

Post by sambo »

You mean even simpler than 3 ingredients ?
User avatar
richardh08
Site Admin
Posts: 2226
Joined: Wed Aug 07, 2013 1:54 pm
Location: Bedfordshire

Re: A crackle challenge

Post by richardh08 »

No.

Ok, I guess this question needs a slightly fuller answer than that :lol:

Let's assume that the key reaction in the report is a thermitic one. That requires a metal oxide and a metal/metal alloy. Since neither of these is likely to act well as a physical binder, a third component is needed to make grains that don't immediately fall apart after they have been formed. I can't see how you could do better than a 3-component mix.

The best simple formulation that Ken and I have so far found contains: CuO, MgAl alloy, aluminium and a binder. Subtract the additional aluminium and you have something that works, but isn't particularly effective. Arguably, that still contains four components if you count the magnesium and aluminium separately.

What I'm talking about is removing one or other of those two metals and still having a composition that reliably produces a reasonably loud report. Everything that we have learned in the last couple of years of experimentation suggests that this might be possible.
Even when I'm wrong, I'm convincing.
davidg
Posts: 280
Joined: Mon Jul 29, 2013 2:07 pm
Location: Manchester

Re: A crackle challenge

Post by davidg »

An interesting challenge. I have been experimenting on these lines but had no luck yet.
User avatar
richardh08
Site Admin
Posts: 2226
Joined: Wed Aug 07, 2013 1:54 pm
Location: Bedfordshire

Re: A crackle challenge

Post by richardh08 »

Here's proof of concept: https://youtu.be/asFa_EO2K1U.

At the moment it's no more than that. It appears that minor changes to almost anything totally inhibit the effect and a lot more time will be needed to figure out why, and what can be done to fix them.
Even when I'm wrong, I'm convincing.
dave321
Posts: 388
Joined: Sat Apr 25, 2015 11:53 pm

Re: A crackle challenge

Post by dave321 »

Richard,

so are you saying this is aluminium/ copper oxide / binder ?
or magnesium / copper oxide / binder ?
if so I am guessing particle size of materials may well be crucial
User avatar
Pyro-Gear
Site Admin
Posts: 3034
Joined: Wed Jul 10, 2013 8:24 am

Re: A crackle challenge

Post by Pyro-Gear »

The former is correct, particle size, aluminium 350# copper oxide around 270-350 #
sambo
Posts: 957
Joined: Sat May 16, 2015 6:04 pm

Re: A crackle challenge

Post by sambo »

Might be of interest - well it's data if nothing else...

I'm making some "nano" copper powder which I will turn to "nano" copper oxide. I'll give it a whirl with the above when I'm done and see what the result is !

Sam
dave321
Posts: 388
Joined: Sat Apr 25, 2015 11:53 pm

Re: A crackle challenge

Post by dave321 »

nano materials will explode easily,
eg. nano aluminium/nano molybdenum trioxide, usually classed as nano thermites

they are a potent area of current research
I have a perfect application for the above combination, which could be turned into a commercial product, but the materials are hard to come by..........any sugestions?

they would certainly explode as a dragons egg ! but would be expensive
User avatar
richardh08
Site Admin
Posts: 2226
Joined: Wed Aug 07, 2013 1:54 pm
Location: Bedfordshire

Re: A crackle challenge

Post by richardh08 »

For preference, I don't like using the word 'expensive' in connection with any pyrotechnic composition!

The mix we have, although a little fragile, seems to behave just like any other dragon egg formulation, and it certainly isn't expensive.

It is sufficiently simple that it ought to be possible to work out exactly what the chemistry is and that, currently, is my main aim.

I'm going to transfer my further thoughts and musings into the Members only section, purely for the purpose of making it slightly less embarrassing for me when I get something completely wrong.
Even when I'm wrong, I'm convincing.
Post Reply