Ignition of ammonium perchlorate and aluminum

[RogueSwimmer]

I wanted to ask anybody who worked with APCP, but specifically just AP/Al without a binder, how easy is it to ignite this mixture with fuse or match. Is it as easy as BP or is it like KNSU/rcandy type of ignition?

 

It looks to burn very bright, indicating high temperatures, which could also be useful for igniting thermites. Has anyone used it as a thermite ignition substitute?

 

Lastly, I have looked into the dangers of mixed AP and aluminum and there are no observed adverse reactions between the two that can cause spontaneous ignition with or without moisture.

 

Appreciate any info.

[oldguy]

Don't play with matches. Good way to toast your fingers.

Visco fuse will ignite AP.

I have used AP 90 Mg/Al 10 compacted in a cardboard tube with a Visco fuse to ignite thermite.

[RogueSwimmer]

Thank you, sir. I looked at decomposition and ignition points of AP and they seem slightly higher than BP at around 450C, so with aluminum it should be even lower.

I would prefer to avoid magnalium with AP because of adverse AP/mg reactions. I may need to store this mixture for extensive periods of time, so it has to be decomposition-free.

 

I am currently looking at AP/Al burning temperature and if I find a document, will post it here. Basically, thermites need at least 1000C + mix to ignite them. If APAL is around there, then it would work.

 

I have found an unverified reference saying that APCP burns 2X hotter than KNSU, which would put it into 1500C range. Better reference is needed, of course. Although I did find another source that puts APCP with 86% solids in the 3200-3300F range, so pure stuff without a binder should b e 1800C+. This is not too far off the thermite temperature by itself.

Edited January 27, 2012 by RogueSwimmer

[oldguy]

If you make your own mgal & water quench it.

It's no problem with AP, as the AL in the mgal passivates the mg content.

[RogueSwimmer]

Initially, I thought APAL may be somewhat harder to light than KNSU propellant because of the melting point of NH4CLO3 is 380C, while KNO3 is 330C. Now, thermal decompositions of AP is lower than KNo3, at 30 kcal/mol vs. 75 kcal/mol. So the two probably have equal ignition temperatures, I would imagine.

 

The addition of aluminum to AP also helps with the hot spot formation, so that should lower the ignition temperature even further.

 

I could be somewhat wrong about this, but I think APAL is as easy to ignite as KNSU.

Edited January 28, 2012 by RogueSwimmer

[oldguy]

Space shuttle SRB motor consists of ammonium perchlorate (oxidizer, 69.6% by weight), aluminum (fuel, 16%), iron oxide (a catalyst, 0.4%), a polymer (such as PBAN or HTPB, serving as a binder that holds the mixture together and acting as secondary fuel, 12.04%), and an epoxy curing agent (1.96%).[4][5] This propellant is commonly referred to as Ammonium Perchlorate Composite Propellant, or simply APCP.

[RogueSwimmer]

^^^^^

Yes, sure. And?

[oldguy]

^^^^^

Yes, sure. And?

 

LOL, an AP/Al comp can lift a space shuttle into orbit.

I assure you it can ignite thermite.

[Seymour]

It's also the melting point of the Aluminium that you have to consider, especially since you're not talking about using a resin that could help it get started.

 

Also, particle size. For example, CuO and coarse atomised Aluminium takes a hot metal fueled or perchlorate mix to ignite it, while with dark flake Aluminium a relatively cool charcoal streamer will do it.

 

Now I know Ammonium perchlorate can make perfectly hot flames, especially with Aluminium, it really does seem almost criminal to use Ammonium perchlorate foor something like lighting thermite. Potassium perchlorate generally makes hotter mixes, but even Potassium nitrate with some Al is happily going to light thermite (even if it needs a prime of it's own).

 

It's no problem with AP, as the AL in the mgal passivates the mg content.

 

If only... I once made the mistake of using MgAl in an AP mix that was not dichromate treated, and had dextrin as a binder. After adding water I got a face full of Ammonia, and a cup of overflowing foam that seconds ago had the potential to be pretty purple fire. I'm sure the problem is much worse with Mg, but MgAl IS NOT unproblematic with Ammonium perchlorate. Dichromate does a lot of good, and I've stored untreated MgAl//AP mixes, with powder dried prior to mixing and bound in NC. That lasted a while, over a year.

 

 

Without pre-drying the chemicals, they go off pretty fast.

 

I have found an unverified reference saying that APCP burns 2X hotter than KNSU, which would put it into 1500C range. Better reference is needed, of course. Although I did find another source that puts APCP with 86% solids in the 3200-3300F range, so pure stuff without a binder should b e 1800C+. This is not too far off the thermite temperature by itself.

 

 

It really depends on the formula doesn't it? You have mixes ranging from metal free and with an oxygen ballance favouring carbon momoxide (or even CO + C), to high metals and an oxygen ballance solidly set on making CO2. The latter, if I remember correctly is going to be closer to 3000deg C than 1500deg C.

Edited January 28, 2012 by Seymour

[RogueSwimmer]

It's also the melting point of the Aluminium that you have to consider, especially since you're not talking about using a resin that could help it get started.

 

Indeed, that came to mind as well. 660C for aluminum and 380C for AP. I believe ratio 75/25 or 80/20, while far from OB would work decent. Higher aluminum to near OB at 40-45% would result in the hottest mix, but would be harder to ignite, methinks. I will try several ratios. With that said, KCLO4 has a melting point of 525C and it can be quite sensitive to heat as 70/30 FP. Part of that is of course the heat decomposion of KCLO4, which is actually slightly negative at -0.6kcal/mol.

 

As far as wasting AP on thermite ignition, this would be really true if APAL burns over 2000C.

Edited January 28, 2012 by RogueSwimmer

[RogueSwimmer]

Anyone cares enough to mix a tiny batch AP with aluminum and try lighting it with 1/4 inch of fuse? I am still waiting on arrival of my AP here.

[anapogeetoofar]

AP and aluminum without a binder and APCP are about as similar as silver fulminate and black powder. Do not use this in any significant amount. Ever.

There is a damn good reason why when making APCP you mix the aluminum with the HTPB before adding any AP. I know of more than one person who has failed to do this and learned not to do it again by receiving a face full of AP/AL fire. Just the friction of being stirred in a bowl set it off, and remember, this is no where near a stoichiometric mixture. A pinch or two of epoxy grade aluminum in a baggie full of AP makes a fantastic exploding rife target. A pinch or two.

If you try to use this in a rocket, it will CATO quite spectacularly, I can assure you. Maybe it would work on whistle tooling, just be damn sure you have a good blast shield.

 

I might be being way to paranoid, but there Your fingers, you be the judge.

 

Just my 2 cents.

[RogueSwimmer]

@anapogeetoofar

 

Thank you for the response and warnings, but please put on your flame suit.

 

I know of more than one person who has failed to do this and learned not to do it again by receiving a face full of AP/AL fire

 

I would like to hear some specifics on the "more than one" cases. I am familiar with the gentleman who mixed 6 micron Al with AP in a coffee bean grinder and some of the mix sprinkled into the motor and started a very hot fire. That's quite irresponsible, but there was no "face full of fire". He was further injured by fighting the 2000C fire with his bare hands.

 

 

Just the friction of being stirred in a bowl set it off, and remember, this is no where near a stoichiometric mixture.

 

I've not yet tested it for any sensitivities, but it doesn't sound like you've tested it either. KCLO4/al is pretty hard to ignite via friction and is a far more sensitive oxidizer. I will obviously conduct diligent testing with it for friction, spark, and impact, but it seems beyond unlikely that it even matches BP sensitivity.

******************************

 

 

I don't think you are paranoid, you just seem to not know exactly what you're talking about. No problem, that's why we have discussions to get to the bottom of these issues.

Edited January 30, 2012 by RogueSwimmer

[Potassiumchlorate]

AP/Al is easily ignited with a visco fuse. a 2:1 mix in an open tube will make a simple but expensive fountain/sparkler.

[RogueSwimmer]

Thank you, Kclo3.

 

Another thing I have just stumbled upon was the rumored corrosion of AP. I've been trying to look up its "rusting ability" on metals and such, but have not found too many sources. I hear people say that it rusts blenders and such, but I'd like to find out more on that topic.

 

Can it really eat away aluminum or steel? This isn't HNO3, for Pete's sake! I know ammonium nitrate when left on the metal in the open air will turn into spectacular blue color and definitely rust the heck out of. I've lost my brass steering spoon to that.

 

 

http://books.google.com/books?id=KXwgAZJBWb0C&pg=RA1-PT109&lpg=RA1-PT109&dq=ammonium+perchlorate+corrosion&source=bl&ots=RfHYEtDxYn&sig=Z8aGNYojpCwcVaLMBbL6bksz3Dg&hl=en&sa=X&ei=hCYnT-CHFIe2twe2_pXWAw&ved=0CDcQ6AEwAw#v=onepage&q=ammonium%20perchlorate%20corrosion&f=false

 

There is some extensive corrosion data on AP vs. metals. Hell, every metal is resistant to AP corrosion, and those that may not be are subjected to boiling temperatures. So it is once again a gibberish that I was reading on here as far as corrosion goes:

 

http://www.amateurpyro.com/forums/topic/3805-ammonium-perchlorate/page__p__52634__hl__%2Bammonium+%2Bperchlorate__fromsearch__1#entry52634

 

Tyron and Optimus are the ones who commented about corrosive nature of AP. Are they still around here?

Edited January 30, 2012 by RogueSwimmer

[Mumbles]

I can speak from some experience with mixes similar to AP/Al. Ammonium Perchlorate is commonly used in colored strobe compositions. These are typically magnesium or magnalium fueled however. These types of mixes are generally quite sensitive, especially to impact. It does not take a very strong hammer strike. They're often mixed with something like vaseline to lower the sensitivity to a reasonable level. Depending on how the mix is processed the stability can be on the order of seconds (ie very poor processing) to a year or so. Some people have been known to have functional mixes for years, but that is not all that common. I do know people who have worked directly with AP/Aluminum mixes, but haven't heard any first hand reports of sensitivities. I do know that they have made some very intelligent and experienced builders rather nervous to be around, but I've also seen them survive lifts and stuff.

 

http://books.google....rrosion&f=false

 

There is some extensive corrosion data on AP vs. metals. Hell, every metal is resistant to AP corrosion, and those that may not be are subjected to boiling temperatures. So it is once again a gibberish that I was reading on here as far as corrosion goes:

 

http://www.amateurpy...h__1#entry52634

 

Tyron and Optimus are the ones who commented about corrosive nature of AP. Are they still around here?

 

I fail to see how you're making any points with that first link. All the data is for stainless steel. Please, enlighten me as to how that corresponds to anything we've talked about thus far with regards to aluminum, or any other metal fuel commonly used in pyrotechnics. You're out of your mind if you think all metals are resistant to ammonium perchlorate.

[oldguy]

If you cut back on the AP about 20% & add 20% Stearine (Stearic acid).

It will make the mix more insensitive. (but, I’m a novice, so take that with a grain of salt)

Works for me.

[anapogeetoofar]

Look, I'm not here to argue about this, so I wont. Go ahead and mix it up, and test it, let me know what happens. Prove me wrong. I have a big mouth, and making me look like an idiot will surely help make it smaller.

Just tread with caution.

 

I can't find any articles or anything for the accidents, one I know happened because I know the man, the other one I have no solid proof of, so lets just consider that statement redacted. All I could find was Don huff's accident, which I think involved a coffee grinder or shop vac. Not really relevant.

 

I do, however have first hand experience with AP/Al. Like I said, pinch or two in nearly a pound of AP renders it in a state where it is quite eager to go high order. If you want the specifics on that, Send me a PM.

I can definitely assure you it will not work as a rocket propellant though. Maybe In whistle tooling, probably not. When bound with neoprene it either CATO'ed or fizzled, I'm going to say when its dry it will be even worse.

 

Tell you what, I'll make up some, document the aluminum %, and see when it becomes sensitive to a .22 subsonic. Maybe I'll try the hammer test tomorrow. Experiments is fun, data is fun, learning is fun. Theres bound to be smoke and noise, also fun.

[RogueSwimmer]

I fail to see how you're making any points with that first link. All the data is for stainless steel

Good eye' date=' sir, I've missed that fine print up on top. I've still yet to find any reference on corrosion of other lower density metals like aluminum, brass, or nickel.

 

AP/Mg mixes are very sensitive, indeed and look to be about as violent as best flash powders.

 

[media']

[/media]

 

If you cut back on the AP about 20% & add 20% Stearine (Stearic acid).

I will definitely consider that as long as it doesn't make the mix too tough to ignite. It would probably decrease the temperature' date=' so that would be a minus.

 

Tell you what, I'll make up some, document the aluminum %, and see when it becomes sensitive to a .22 subsonic

 

I don't intend to detonate basic AP/AL, but if you feel like shooting it, go for it. Aluminum sensitizes it, but there is still a critical diameter of 20mm+ and it would have a velocity of your Kclo3 cheddite or ammonal if not pressed. . And it is not more sensitive than ammonal. That's why I am about 99.99% sure you won't detonate it by any friction or hammering it (unless you have a sledge hammer), but whether it can be ignited is a different question. I don't think it can be, because it is a slow burning mix. Slow compositions tend to have lower sensitivity to stimuli, usually.

 

I am far more concerned about corrosive nature of AP/Al as for storing purposes.

Edited January 31, 2012 by RogueSwimmer

[anapogeetoofar]

And it is not more sensitive than ammonal.

Yes it is, I have first hand experience with that. You even said yourself

Slow compositions tend to have lower sensitivity to stimuli, usually.

AN/Al mixtures burn far slower than than the AP equivalent, safe to assume greater sensitivity, no?

Though experience really isn't necessary, considering I can't think of a single amine (or alkali, or organic) perchlorate that isn't significantly more sensitive/reactive/unstable than its nitrate cousin.

 

I am far more concerned about corrosive nature of AP/Al as for storing purposes.

 

Oh, well, the lids in mason jars I assume are mode of some sort of low grade steel, and I store all of my AP in them without any noticeable corrosion whatsoever, rubber seals are good as new as well. Aluminum doesn't seem to be affected either, at least with a dusting of dry AP, might be different when in solution, or in a high moisture situation. Though I do live in Florida so I think "high moisture" is covered. I don't think long term storage will be much of a problem if stored airtight.

Obviously with a binder it does just fine, even with Mg. Perhaps you could granulate it with neoprene, red gum, NC lacquer or the like. What exactly is your intended application?

[RogueSwimmer]

AP/AL is less sensitive than ammonal as HE, but obviously more sensitive as pyrotechnical mixsture, because ammonal is not even used as such, being next to impossible to light. With that said, AP/Al is no more dangerous than black powder based on the burn rate and ignition temperature. If you were to grind BP in a coffee grinder you would get a plastic pipe bomb, too. Nobody is stupid enough to try that with black or smokeless powders, right? And those are not "extremely" dangerous by any means.

 

I am experimenting with underwater welding/ metal cutting. I need AP/Al either to be as my main pyrotechnical charge or at least ignite thermite.

Edited January 31, 2012 by RogueSwimmer

[RogueSwimmer]

Just to update from my experiments, because there is some serious misinformation going on here.

 

Tested AP (325 mesh) with spherical aluminum (650 mesh). 75/25. It can ignite with a fuse, but it needs to have at least 10mm of fuse be embedded in it. I had to light it with KNSU/Si mix. Burns nice and bright....and very slow.

 

Friction- got nothing.

 

Impact- well, I've got it to detonate from a relatively modest hammer swing. That was very unexpected because I've failed to detonate DBSP and CuO/Al thermite with similar efforts. So, if you like exploding targets, this is a good candidate for a low-powered rifle.

 

 

I wouldn't mind lighting this mix with dry KNSU/Silicon mix, but the incompatibility of KNO3 and AP as well as that of KNO3 and aluminum has me ruling against it. While they won't be mixed, one will be on top of the other, so some reaction may happen over time.

[anapogeetoofar]

Got exactly the same results, strangely unresponsive to friction, but definitely responsive to a hammer blow, which I expected considering my previous experience with it. This was with 200 micron AP though, no idea what finely ground would be like.

 

I wouldn't mind lighting this mix with dry KNSU/Silicon mix, but the incompatibility of KNO3 and AP as well as that of KNO3 and aluminum has me ruling against it. While they won't be mixed, one will be on top of the other, so some reaction may happen over time.

 

KClO4/silicone/Al 60/20/10 Burns hot, real hot. Is also completely moldable/castable I use it to ignite ANSIAL propellant grains, which you can literally hit with a blowtorch for minutes without getting more than little flare-ups.

Just make sure to either use GE, or a neutral cure silicone, which can be ordered online.

 

And just out of curiosity, since I know absolutely nothing about underwater welding, would the large amount of corrosive gas produced by AP not make for poor welds? I cant imagine hot HCl would make a fantastic replacement for argon.

[RogueSwimmer]

It's more a cutting, not welding. For welding, I'd have to suit up in scuba, which I have no intention of doing with whatever it is that I design.

 

Thanks for the tip about PP mix.How easy/hard is it to light it, btw?

Edited February 5, 2012 by RogueSwimmer

[anapogeetoofar]

E matches primed with BP ignite it just fine.