dangerous amateur
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PbN6 and the use of dextrine
Hi there.
maybe you guys can help me a little.
I recently started experimenting with energetic materials and I'm about to try lead azide.
As far as I understand, dextrine or some stuff with equivalent behaviour is always added before the metathesis to prevent the growth of bigger
crystals.
Documents concerning LA often mention different types of lead azide.
RD 1333 grade, and "dextrinated" lead azide.
Dextrinated seems to be less sensitive.
Does that mean dextrine is added a second time to act as a phlegmatiser, or is this referring to the use of dextrine during the metathesis, and maybe
some dextrine trapped inside the crystals?
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quicksilver
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It's not "bigger" crystals that are of serious concern. It's crystal formation. Needles crystals in existence at any level is forbidden. Industrially
any needles demanded a destruction of the material*. Davis has some very important things to say on this. In the synthesis, temperature appears to
promote formation of needle crystals. Dextrin percentage addition via saturated solution during wash does inhibit formation later and during initial
however, there was a great deal of controversy dealing with industrial production as yield issues promoted higher temp while safety concerns appeared
to demand the opposite.
This is generally why the use of a microscope is often considered mandatory in synthesis of lead azide. The particulate will be single micron & a
very small percentage of needles will not be seen without microscopy. Azides (in particular lead azide) has a low threshold initiation to static.
Please read Davis and Federoff thoroughly prior to synthesis. There is an enormous amount of things to be concerned with dealing with azides. Not the
least is the level of toxicity. The welcome news is that there are some very in-depth quality, peer reviewed data that one can get the most
appropriate information from. Remember that patents will not reveal many safety issues & are often concerned with yield issues. Industrial
information, specifically concerning safety is strongly advised prior to any synthesis. The LD50 is very close to cyanide. The correct sizing is
easily air borne particulate. Use extremely high levels of caution, very small weight precursor, and effective protective equipment.
edit:
*That not a percentage of needles....it's any at all!
[Edited on 9-7-2011 by quicksilver]
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The WiZard is In
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Dextrin
As far as I understand, dextrine or some stuff with equivalent
behaviour is always added before the metathesis to prevent the
growth of bigger crystals.
Yes. However, dextrin is a was.
You can DL RD-1333 you may find it interesting.
djh
----
I would be remiss if I didn't note that the
British experience one unexpected explosion
during production of service lead azide for
every 6 000 batches.
[GWC Taylor Hazards in Manufacture And
Loading of Lead Azide. Proceedings of the
Symposium on Lead And Copper Azides
Held on 25th-26th October 1966. Explosives
Research and Development Establishment
Waltham, Abbey, England AD A011 026].
Like the IRA said of their failed attempt to
blow-up Margaret Thatcher —
She has to be lucky all the time. We only
have to be lucky once!!
Do you feel lucky today? ... Punk!
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The WiZard is In
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Quote: Originally posted by The WiZard is In  | As far as I understand, dextrine or some stuff with equivalent
behaviour is always added before the metathesis to prevent the
growth of bigger crystals.
Yes. However, dextrin is a was.
You can DL RD-1333 you may find it interesting.
|
And DL — Laboratory assessment of service lead azide and
the alternative forms RD1343 and RD1352., &c. All tooo large
for me to post here.
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The WiZard is In
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| Quote: Originally posted by quicksilver | | It's not "bigger" crystals that are of serious concern. It's crystal formation. Needles crystals in existence at any level is forbidden. Industrially
any needles demanded a destruction of the material*. Davis has some very important things to say on this. In the synthesis, temperature appears to
promote formation of needle crystals. Dextrin percentage addition via saturated solution during wash does inhibit formation later and during initial
however, there was a great deal of controversy dealing with industrial production as yield issues promoted higher temp while safety concerns appeared
to demand the opposite. |
LEAD AZIDE
MIL-L-3055C
12 January 1992
SUPERSEDING
MlL-L-003055rI(AR)
26 April 1985
MIL-L-3055A
28 September 1962
[US] MILITARY SPECIFICATION
LEAD AZIDE
1.2 Classification. The lead azide, detailed in this
specification, shall conform to one of the following types (see
6.2).
Type I - Dextrinated lead azide
Type II - Colloidal lead azide
3. REQUIREMENTS
3.3 Dimensions. (for Type 1 only). The lead azide shall be
free of needle shaped crystals (needle shape crystals are defined
as crystals having a length/diameter of 7/1 or greater) when
examined as specified in 4.5.3.
3.4. Particle size. The particle size
4.5.3 Dimension. (for Type I only). Examine the slide
prepared in 4.5.2 using a minimum magnification of 150 times and
reflected light for presence of needle shaped crystals. Measure
the longest dimension of the crystal with the aid of a mechanical
stage. For this examination, use transmitted and reflected light
and an ocular micrometer which has been calibrated by means of
the stage micrometer. Consider the longest dimension to be the
distance between the two most remote points of any one crystal.
A minimum of 100 crystals shall be examined.
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quicksilver
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Right on the money!
Free of needles means just that.
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hissingnoise
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Davis's "COPAE" can be downloaded from the site library, BTW . . .
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The WiZard is In
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Military Specification Lead Azide RD-1333 [CMC]
3.2.2.1 Aggregates.—The aggregates shall contain no well
defined translucent crystals when examined microscopically
(see 4.3.2) similar to Figure 6.
4.3.2 From - Major Defect - Defect Code 08001.-Spread a
thin layer of the sample on a glass slide and allow to dry
at room temperature. Examine this material under a
microscope using a magnification of approximately 150.
djh
---
And now something completely different.
AD-AO11 026
PROCEEDINGS OF THE SYMPOSIUM ON LEAD AND COPPER
AZIDES HELD ON 25TH-26TH OCTOBER 1966
Explosives Research and Developmernt Establishment
Waltham Abbey, England
26 October 1966
DISTRIBUTED BY:
National Technical Information Service
U. S. DEPARTMENT OF COMMERCE
"Brass azide", Cu SUB xZn SUB (1-x) (CH)N3, has a variable composition due to solid
solution formation as indicated by X-ray powder photographs and chemical
analysis of different samples. It can be prepared by mixing a suspension of
basic zinc azide with dilute copper and zinc porchlorate solutions and ageing
the crystals in the mother liquor for at least 6 months. Best results lere
obtained with 0.6 g. basic zinc azide + 9.5 ml 0.1 M zinc perchlorate + 1.5 ml
0.1 M, copper perchlorate + 90 ml water. Basic zinc azide was prepared by
precipitation of IV sodium azide with an equal volume of 0.5M zinc perchlorate at 80o - 90o C.
-
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hissingnoise
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In the micrograph of service (dextrinated) Pb(N<sub>3</sub> <sub>2</sub> in COPAE there are no crystal faces visible!
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The WiZard is In
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Large crystals
some it would seem want large crystals!
 
Attachment: Lead azide crystallization.pdf (156kB)
This file has been downloaded 1004 times
Attachment: Lead azide controlling reactivity.pdf (571kB)
This file has been downloaded 949 times
djh
----
Rules of the lab
1. When you don't know what you're doing, do it neatly.
2. Experiments must be reproducible, they should fail the same way each
time.
3. First draw your curves, then plot your data.
4. Experience is directly proportional to equipment ruined.
5. A record of data is essential, it shows you were working.
6. To study a subject best, understand it thoroughly before you start.
7. To do a lab really well, have your report done well in advance.
8. If you can't get the answer in the usual manner, start at the answer and
derive the question.
9. If that doesn't work, start at both ends and try to find a common middle.
10. In case of doubt, make it sound convincing.
11. Do not believe in miracles--rely on them.
12. Team work is essential. It allows you to blame someone else.
13. All unmarked beakers contain fast-acting, extremely toxic poisons.
14. Any delicate and expensive piece of glassware will break before any use
can be made of it. (Law of Spontaneous Fission)
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dangerous amateur
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Thanks for your replies.
Well, I don't have a respirator, and I don't have a microscope.
I guess that puts me out of business...
When I do it I want to get a product that is as insensitive as possible. This stuff has to many variables I cannot control.
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Fusionfire
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What is interesting is that small crystals of lead azide have a deflagration velocity of 600 m/s, but large crystals have a detonation velocity of
8000m/s (both initiated by an exploding wire). See Chaudri, M.M. & Field, J.E. (1974) Proc. Royal Society London A 340, pp. 113-128
If someone has access to an electronic copy to share with the rest of us that'd be great, I just have a paper one.
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quicksilver
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It's the mature & appropriate thing to assess the issue from all sides. It's seriously - one nasty bastard IMO (PbNO3). Industry sample
micrographs will not display a single needle. They destroy a sample that exhibits such. The material is generally in the single micron (2-9um) size
range and maintains a "chalky" texture when properly mfg. The needle samples made for comparison photographs are mfg in the low milligram range.
Frankly, many of the more "unique" primaries are a degree safer. It's occasionally said that as the synthesis gets simpler the safety level gets
narrower.
There are some very interesting alternatives in the large "primaries" thread.
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hissingnoise
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| Quote: | | It's occasionally said that as the synthesis gets simpler the safety level gets narrower. |
Trinitrotriazidobenzene, safe to handle, difficult to synthesise but what a primary?
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mabuse_
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| Quote: |
a "chalky" texture |
That's how mine looks. Like wet chalk (but it's dry).
| Quote: |
I don't have a respirator, and I don't have a microscope. |
Me neither.
I always handle it in a way that a spontaneous detonation won't hurt me (I think).
Not a proper solution though.
The thing is, if you abuse the stuff, it's actually very hard to set off. It requires a strong blow with a hammer, and rubbing it with the hammer over
a concrete surface failed to set it off.
It gives one a feeling of relative safety. On the other hand this might be very well a stochastic thing. Maybe sometime there is a needle in the right
position and triggers the stuff from a far lower stimulation.
Silver acetylide/nitrate double salt may be an alternative, there also seem to be some very interesting compounds based on 5-ATZ, what will be my next
eperiment.
I know all to practical discussion is not wanted here but anyway:
It IS possible to make reliable detonators with a setup that provokes ETN to cook off. IMHO hard to beat in terms of safe handling...
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quicksilver
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There is a very good reason why I say that was a mature decision on the part of the OP.
I have built computers since around the late 1980's - that's a long time.... by the way. I was building one for a close friend rather recently as he
wanted a "gaming computer" that he was willing to spend about $2000 for and was unfamiliar with Overclocking (done correctly). But he was too paranoid
to put it together himself. I took the responsibility and was familiar with the AMI CMOS issues & heat problems of both the mobo and processors. I
was winding up and I was installing the RAM when it happened. I forgot for one time only to ground myself and had to buy some new RAM.
My little story here is obvious. I have been working with static issues for a very long while. And I forgot only once (maybe twice) going back to when
computer ran on DOS 3.31 XT chips and 640k was considered big memory. IF that was not a RAM chip card but a sample of a primary I would have
negligently harmed myself through carelessness. Let's say I built my 1st computer in 1989, that's 22 years of experience. I lost about $40 but I
learned a very valuable lesson. I NEVER thought I would make that type of error; but I did. And, YES, the static issue DOES actually screw up certain
components in a computer. Some people haven't seen so they think it's too rare to consider......but it really does.
On another level:
The issue with practical discussion is the level of depth. A comment on whether one material has better initiation value than another is totally
within bounds. The concept is one of going overboard would be: "here is my new CAD of a pressing machine for det caps".
It's almost like pornography. It's a bit tough to define but you know it when you see (or read) it. 
[Edited on 13-7-2011 by quicksilver]
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dangerous amateur
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I'm aware of ESD. Fortunately I've got a little table with a metal workplate. I think that should kill most potential differences.
| Quote: |
interesting compounds based on 5-ATZ |
Can you propose a certain compound? I'm a little lost due to the vast number of possibilities...
Are there some commercially used among them yet?
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hissingnoise
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| Quote: | | It's almost like pornography. |
Except that the masturbation induced is purely mental . . .
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Herr Haber
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Unless I totally misunderstood every topic about LA on Sciencemadness *needles are bad*
That would mean that I totally misunderstood Davis and Urbanski too.
Someone on Wikipedia was very ill advised when he chose his picture:
https://en.wikipedia.org/wiki/Lead(II)_azide
These needles seem to be VERY large dont you think?
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hissingnoise
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More on the sensitive ß-lead azide from NatureScience . . .
(LEAD azide, PbN6, exists in two allotropic forms1,2, one (α) orthorhombic and the other (β) monoclinic. α-Lead azide is readily prepared by mixing
in the normal way solutions containing azide and lead ions; β-lead azide crystallizes as needles when aqueous solutions of sodium azide and lead
nitrate interdiffuse slowly1. Table 1 summarizes the crystallographic relations1,3. Both forms are explosive and α-lead azide is in common use as a
detonator. It is said1,2 that β-lead azide is much more sensitive and dangerous than α-lead azide.)
http://www.nature.com/nature/journal/v176/n4483/abs/176653a0...
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