Sickman
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Casting Metal Picrates
Casting Metal Picrates
Examples: Melting Point / Ignition Temperature
Sodium Picrate 210 / 313
Potassium Picrate 250 / 331
Calcium Picrate 316 / 323
Chromium Picrate 275.5 / 296.5
Cobalt Picrate 226 / 327.5
Strontium Picrate 290 / 341
Silver Picrate 296 / 332
Barium Picrate 200 / 332
Note: all temperatures are in degrees Celsius. Dehydration temperatures have been omitted.
Reference: Urbanski, Chemistry and Technology of Explosives Table 119
Given the fact that in the above examples the average range between the melting points and ignition temperatures is 66.5 degrees Celsius, with some
being much wider and others narrower, it seems possible that many metal picrates may be safely melted and cast.
The potential of cast metal picrates may find many uses; There crystal structure and explosive properties changed. Various materials such as oxidizers
and fuels may be added to them to further change their properties.
These cast metal picrates may be useful in the form of a cast pellet with a bridgewire inserted before solidification of the melt for use as an
electric match.
There may be drastic changes in explosive properties between a cast picrate and free flowing picrate crystals. As with most cast explosives the
material is likely to be desensitized. The deflagration to detonation transition speed may increase or reversly may not be realized at all. If
casting does in fact enhance the initiatory abilities of the picrates it may be promoted from a flash igniter to a more useful primary explosive,
capable of initiating the detonation of certain sensitive secondary explosives.
Regrettably, I’ve been unable to find very much more information about other picrates' melting points. For example: Lead Picrate. Any more info
would be appreciated! I have several experiments lined up to see what is possible with casting metal picrates.
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Rosco Bodine
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My CRC states lead picrate melts at 130C with loss of its 1 H2O .
You will find that increasing the density actually slows
the DDT for these materials which behave more like
a flash powder on steroids , they DDT rapidly when loose
but burn when compacted . You will likely never get the jump in self-accelleration needed to make any of these useful as high ordering primaries
capable of detonating
secondary high explosives by impetus or impulse in
any reasonably small quantities .
And you are contemplating some dangerous experiments there , which I can't recommend or really see any value ,
except to at great risk likely confirm what I'm saying .
Complementary mixtures of basic lead picrate with other materials or complex multiple salts , clathrates , ect .
would be more worthwhile and much safer experiments .
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Sickman
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Yes, Rosco!
The whole "be a better explosive" comment was simply to get people thinking as I never casted a picrate before, I would'nt know what will happen as
far as faster or otherwise VoD is concerned.
My main interest, and I may call it my sole interest now in picrates is in creating reliable electric matches.
The idea is to use nitrocellulose laquer as a binder or simply cast the picrate. To form stable, "tough", reliable, ignition capability.
As you say a loose powder is better, perhaps a picrate cast bridgewire in combination with a loose powder of the same picrate would make a chemically
compatible and reliable "situation" for igniting pressed primary explosives only, of course!
[Edited on 2-9-2006 by Sickman]
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quicksilver
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One of the most interesting Ematch issues I have worked with is a bridgewireless electric match utilizing 95% lead styphnate and 5% graphite. Made an
intimate mix by the use of wetting: this will funtion with as little as one amp.....it does work and work well.
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Mr. Wizard
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What voltage was driving the one amp? Did you mean one volt?
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franklyn
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| Quote: | Originally posted by Rosco Bodine
you are contemplating some dangerous experiments there , which I can't recommend or really see any value ,
except to at great risk likely confirm what I'm saying . |
Put that in C A P I T O L letters
Given Picric acid has been in military use for 120 years and through two world
wars , I think it unlikely any overlooked preparation of it has missed attention.
Industrially, the sort of treacherous processing you suggest would be performed
remotely by robots. No one uses Picric acid for anything but as a dye nowadays.
Read the image below at the middle of page 164
in " The Chemistry of Powder and Explosives by T.L. Davis " from the library
http://www.sciencemadness.org/library/books/the_chemistry_of...
Page five is omitted but states " ALL metallic picrates are primary explosives "
and the last image from Military Explosives read about " accidental explosions "
.
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quicksilver
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| Quote: | Originally posted by Mr. Wizard
What voltage was driving the one amp? Did you mean one volt? |
..... compound tested and it works with a pair of D cells. (3v). In that what would provide heat to light a flashlight bulb would get this hot enough
to pop. There are a few variables here but most importantly is the weight / size of the level of material effecting the resistence.
Enclosed is the patent (tough to find) dealing with the original testing. It was indeed utilized but had some issues with static and was replaced by a
much more expensive bridge-wire-less dip material utilizing zirconium at a sub-sieve level instead of graphite.
Attachment: BridgeWirelessDetonators_ Styphate.pdf (176kB)
This file has been downloaded 770 times
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Sickman
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Franklyn,
"Industrially, the sort of treacherous processing you suggest would be performed
remotely by robots. No one uses Picric acid for anything but as a dye nowadays."
This statement seems very ignorant. The references you have sighted prove more than they disprove that picric acid and the picrates are safe to
manufacture and handle.
In fact the manufacture and handling of black powder is more hazardous in my experiance than that of Picric acid and picrates.
Your last reference states that several picrates are comparable to high explosives some being even less sensitive than TNT.
In many trials conducted by me a severe hammer blow was required to get most of the picrates to do anything.
If it were up to me I would classify the picrates not as primary explosives, but rather as pyrotechnic molecules, because they don't behave like
primaries such as silver fulminate and lead azide, creating a high order detonation wave, but rather have a very fast flame front. They are also far
less sensitive to impacts than any "unequivical primaries". They behave like Rosco said very much like a fast flash powder.
All energetic materials are hazardous to a degree, but using a policy of safety first, usually keeps things safe when we combine it with common sense
and knowledge.
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franklyn
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| Quote: | Originally posted by Sickman
Franklyn, This statement seems very ignorant.
| Quote: | Originally posted by franklyn
No one uses Picric acid for anything but as a dye nowadays. |
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I consider pyrotechnic formulas for fireworks to be a trivial use
You remind me of those people who leave dried handprints next to the sign that says wet paint.
The sensitivity and reactivity of pressed crystals is not the same as for the molten picrate.
Very few secondary explosives are even melt cast and at less than the boiling point of water.
For that they are blended with TNT or a low melting polymer binder , most are just pressed
in a softened state.
I've had the idea that just as phenol and formaldehyde can form bakelite, picric acid
could also form a polymer plastic. If this would form at all it would be a better option.
[Edited on 4-9-2006 by franklyn]
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