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Axt
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Bi-metallic Fuse and intermetallic reactions
An idea that arose from the thermites file on FTP2 - A survey of combustible metals, thermites, and intermetallics, this file shows some
metal-metal reactions are quite energetic. One of the best was palladium/Aluminium.
Reaction temp - 2653K
State of product - liquid
Heat of reaction - 2890 (cal/cm3)
Thats all good.
Therefore I tried twisting palladium wire around aluminium, the problem here was the Pd was 0.2mm against the Al of 1mm. I used 4:1 ratio of the
strands but that was still nowhere near enough palladium.
Hitting the wire with the propane torch resulted in a bright light but the fuse-wire wouldnt sustain, usually only travelling about 1cm. Crappy movie
of this --><a href="http://www.geocities.com/roguemovies5/index.html">movie</a>.
Getting the shits I wrapped 50cm of Pd around about 4cm of Al, this fired up and burnt very fast, at a guess about 1m a second. unfortunately I didnt
video this but it shows that it does have promise as a fast silent fuse if you can get both wires in 0.2mm and braid them together.
Hardly cost effective .. but fun!
[Edited on 22-6-2004 by Axt]
[Edited on 30-6-2005 by chemoleo]
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Axt
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Forgot to say, the molten alloy exploded into a shower of sparks when it hit the ground, a few of which can be seen in the movie. Somewhat like a red
hot lighter flint against concrete, except it was bright white.
Just giving observations.... I dont think there are any cheaper wires to play with that are likely to work.
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Axt
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Grrr .. how long are you open to edit these posts?
Nickel looked like it may do something useful, so I tried 0.6mm nichrome around the 1mm Al, after heating it red hot for about 10 sec. it glowed
brighter red for a couple seconds as it fused together ... that is all. Looks like only the expensive ones will be interesting with Al.
Ti/C looks to be good as well! If someone has Ti powder from a pyro supplier mix with carbon and see what happens. I think ive read about Ti/B being
used as an underwater explosive in a patent somewhere (yields gaseous products).
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PHILOU Zrealone
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Following the movie you showed only one metal wire takes fire...my guess is that it would burn aswel on its own...
Also the important thing is the presence of oxygen it being taken from water after preheating or from the air...so surface contact is important....you
obviously took this in account in your second experiment with a sheet of Pd rolled.
No real uses then or advantages vs Mg/Al alloy fine ribons coated with NC and tressed in a rope kind of fuse.
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Axt
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Im somewhat lost by your comments.
The wires are twisted together therefore if one burns they both do, and individually aluminium and palladium glow red and melt, they dont burn bright
white.
The second experiment was exactly the same except far more Pd was wrapped around the Al for its length. Effectively it was an Al core sheathed in Pd.
I must not have stressed how fast this was, the 4cm was gone in an instant with a funny glow followed by bright white "flame" .... At least
thats what I remember as it took me by surprise, and with such a short length.
I believe it propagates by the reaction between the metals rather then atmospheric oxygen or water. Though im not curious enough to burn up more
palladium to find out 
Obviously im not suggesting people start using palladium fuses in their M-80's but this is mad science isnt it! 
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PHILOU Zrealone
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Sorry I don't see what reaction between those two metals if no oxygen and no water is present?
Aluminium paladide?
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Marvin
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Eutectic formation at a guess.
Sodium (or is it potassium) and mercury are supposed to emit flashes of light as they are touched, likewise you are supposed to get flashes of light
from the reaction that forms the sodium-potassium eutectic.
I assume the flashes of light have to be thermally produced.
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chemoleo
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A reaction does take place, with distinct stoichiometric proportions.
For instance, taken from here :
http://www2.latech.edu/~bli/JMR2000.pdf
(Also see http://www.metalfoam.net/papers/kobashi02.pdf )
Ni + Ti → NiTi + 67kJ mol-1 (1)
Ni + Ti → Ti2Ni + 83kJ mol-1 (2)
Ni + Ti → Ni3Ti + 140kJ mol-1 (3)
Ni + Ti → Ni4Ti3 + heat (4)
With the reaction heat and the heat provided by pre-heating, combustion becomes self-sustaining. As NiTi, Ti2Ni
and Ni3Ti are three stable phases while Ni4Ti3 is metastable in NiTi alloys, reactions (1), (2) and (3) always take place and reaction (4) only occurs
at pre-heating temperature below 525°C.
Anyway... there are a number of reactions of interest... with metals/non-metals that are easily available :
Al + 2B ---> 742 cal/gram (-Q, heat of reaction)
4Al + 3C --> 371 (not exactly intermetallic)
2Al + Ca --> 558
3Al + Fe --> 278
Al + Li --> 345
Al + Ni --> 330
Al + Pd --> 327 (so not really that high)
2Al + 3S --> 800 (not exactly intermetallic)
2Al + Ti --> 314
2B + Mg --> 479
Be + 2C --> 1750 (well...(not exactly intermetallic again)
Ca + Si --> 529
2Ca + Sn--> 377
Fe + Si --> 225
Mg + S --> 1500 (a little higher huh...)
[Edited on 23-6-2004 by chemoleo]
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Axt
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| Quote: | Originally posted by chemoleo
Al + Pd --> 327 (so not really that high) |
Yes, but what is more important in regards to wires twisted together, energy per gram or energy per volume? I chose the latter for my assumptions
which places the Al/Pd higher up the scale. Also most of the others cant be sourced in wires.
The state of the product may also have an influence on the ability for the reaction to propogate as hinted to in the combustable metals file, liquid
products are more likely to self sustain then solid products, rules out Al/Fe etc.
[Edited on 24-6-2004 by Axt]
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Axt
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Better movie added,
<center><img src="http://www.sciencemadness.org/scipics/axt/pdalfuse.jpg">
<a href="http://geocities.com/roguemovies6/">MOVIE AVAILABLE</a></center>
As was posted in the other thread, twisting Al foil around the tiny 0.2mm Pd wire gave a better (easier) ratio then wrapping a load of Pd around the
heavier 1mm Al wire as before, though I think it was slower burning at about 5" a sec with a lot less wire involved.
Is there any good online sources for metal wires? I found a british one <a href="http://www.advent-rm.com/default.asp">here</a> but the
prices are fucking rediculous about 10x more then I pay for Pd.<br>
[Edited on 9-12-2005 by Axt]
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Axt
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Nichrome will sustain a reaction with Al ... just. The reaction procedes lazily with no flame at about 2" a second.
<center><img src="http://www.sciencemadness.org/scipics/axt/nichromeal.jpg">
<a href="http://geocities.com/roguemovies6/">MOVIE AVAILABLE</a></center><br>
[Edited on 9-12-2005 by Axt]
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Nick F
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I've been playing with Al/Ni in powder form. My Al is bright flake (the really annoying kind which floats around in the air and covers
everything), and the Ni is a dark, dusty powder.
It certainly works, in fact I might be able to get a vid... And both powders are easy to get in the form of resin additives.
Al forms a eutectic with Cu, I wonder if there might be a good reaction between these two? Shouldn't be hard to find out...
(Does it even have anything to do with eutectic formation?)
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Marvin
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To a certain extent eutectic behaviour is just evidence for formation of a compound. But then all a compound really is in physical terms, is a
certain ratio of reactants that gets the most energy out. For covelently bonded molecules or ionic salts these corrispond well to formal charges, ie
electron swapping. For metallic lattices and van der waals systems in solution things are less obvious.
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Axt
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| Quote: | Originally posted by Nick F
I've been playing with Al/Ni in powder form. |
The product may be more interesting then the reaction, if it is as pyrophoric as the PdAl or Hf (or whatever it is in lighter flints) it may be quite
amusing to load some into, or on top of a HE.
Ive never seen Ni as a resin filler, but I have Cu and it wont react with Al, at least not in a self sustaining reaction.
I am interested in seeing it as a movie, get it up if you can.
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Nick F
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Well, a eutectic might be a good place to start. I had a look at my metallurgy notes on microstructure, unfortunately the diagrams are awful. The
Al-Cu phase diagram looks like it has a couple of dozen regions, but I can't read any of the numbers or labels (such as crystal structure etc, I
guess higher density forms are desired). I'll see if the online version is clearer...
The Al/Ti combination could be useful, since both metals are fairly cheap in the form of fine wires which could be braided together to give the right
ratio, and both metals are flammable in air, which would help things along a little.
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Nick F
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The AlNi doesn't appear to do anything interesting, although I haven't done any serious experiments with it. Just a boring-looking black
powder...
I don't expect it to be pyrophoric, if it was going to oxidise then I think it would have done so while it was still glowing white hot after the
reaction  (it is produced as a powder, rather than a blob, so surface area is
high...)
Lighter flints are misch metal, ~80% cerium, other rare-earths as impurities, and some iron and magnesium, usually. There was a 1lb chunk of it on
ebay once, quite cheap too. Don't know why I didn't buy it  .
And I stand corrected - the resin filler was nickel silver. I couldn't find exact figures for its composition.
AlNi video coming later tonight, hopefully...
[Edited on 8-7-2004 by Nick F]
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Axt
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Actually, check patent US 4,880,483. The "pyrophoric iron & nickel" refered to is FeAl and NiAl, generated enough heat to ignite
thermite. NiAl is said to generate higher temps then FeAl.
______________________________________
1 part pyrophoric iron powder
2 parts zirconium powder
3 parts ferric oxide powder
______________________________________
All powders being about 325 mesh in size will spontaneously ignite when exposed to air and generate sufficient heat to melt through a 30 mil thick
1010 steel sheet on which the mixture is held.
Similar results are obtained when aluminum powder is substituted for some or all of the zirconium powder, Fe.sub.3 O.sub.4 is substituted for some or
all of the ferric oxide, and pyrophoric nickel powder substituted for some or all of the pyrophoric iron. The content of pyrophoric powder can range
from about 15% to about 30% of the mixture, by weight, and the proportion of thermite metal oxide oxidizer to thermite metal reducer should be close
to stoichiometric as in any thermite mixture.
EDIT: Reading it again, it seems to me that the "pyrophoric iron/nickel" is actually the NiAl that has had the Al leached out with a basic
solution, creating a massive surface area inside the metal grains, still useful.
[Edited on 11-7-2004 by Axt]
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Nick F
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That would be interesting to try. I'll try to set off some mixture in a container which will limit air exposure, then react it with sodium
hydroxide solution...
I'm having some problems with my camera software, but I'm still confident that I'll be able to get a video at some point...
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Nick F
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Here's a vid of a couple of grams of NiAl. I set it off on the mdf board to provide a reducing atmosphere, so I can try to make some pyrophoric
Ni from the residue. The camera didn't cope very well, but it'll give you a rough idea of what it's like. At the start, all that is
burning is a little\pile of Mg shavings. I had to blow on it a little to get the flame up and ignite the NiAl, although normally that isn't
necessary.
Enjoy!
Edit: I have realised that the video is about 7Mb, and is therefore to big to attach... I'm looking for other ways to show you!
[Edited on 12-7-2004 by Nick F]
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Axt
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Im interested in how energetic it is, as plating Ni onto Al wire may be the only practical way of creating an intermetallic fuse, though the plating
process looks difficult. Axe's FTP2 might help if you cant reduce it.
Leached Ni seems to be the catalyst in these new fangled hydrogen fuel cells as well, another interesting use.
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Nick F
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Yes, I'll have to get an FTP account...
It seems a little less energetic than CaSO4/Al. I'm not sure how well a simple Al cored, Ni coated fuse would work. For the fuse to be of a
useful diameter (ie, a diameter that is thick enough to sustain the reaction), I think the metals would be too thick, and not in intimate enough
contact. I think the way to do it would be to coat fine Al wires in Ni, and then twist several together until you found a size that worked. Or simply
twist fine Al and Ni wires together in the right ratio, this would certainly be easier.
You can see from the table below that it has more cal/gram than AlPd, so I think it would be quite possible to make a useful fuse...
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Axt
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Table below?? ... I know what you mean
Ni has a shade on Pd by weight, but not by volume.
NiAl = 1710 cal/cm<sup>3</sup>
PdAl = 2890 cal/cm<sup>3</sup>
CrAl<sub>3</sub> = 430 cal/cm<sup>3</sup>
Your right that the surface area and intimacy has a large influence on how well it will propagate, the NiCr (80:20) wouldn't fire when a single
0.6mm wire was used but did when 3 fine 0.25mm wires were wrapped into the Al, the Pd would fire along a single 0.2mm wire.<br>
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chemoleo
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Just out of interest - how about mixing Al powder and Ni powder? I guess Ni powder could be made by reductiion of a Ni-salt solution, like with Zn
powder.
I haven't checked whether it would work, but there are a number of other metal powders worth investigating... such as Fe, Pb..etc!
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Nick F
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In my first post on the subject:
"I've been playing with Al/Ni in powder form. My Al is bright flake (the really annoying kind which floats around in the air and covers
everything), and the Ni is a dark, dusty powder."
Oh, yeah, the table is normally above, isn't it! Well, it's below when you're replying! Oh, yeah, Pd kicks Ni's ass, doesn't
it .
I have chromium powder aswell, but I don't want to waste it for 430cal/cm3! Well OK, maybe just a tiny bit...
I'd really like to find a good zinc-based mixture... Anyone?
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Axt
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| Quote: | Originally posted by Nick F
I'd really like to find a good zinc-based mixture... Anyone? |
Only exotic ones,
Zn<sub>2</sub>Zr = 1160 cal/cm<sup3</sup>, will probably sustain.
CeZn = 535 cal/cm<sup3</sup>, will probably sustain.
PuZn<sub>12</sub> = 600 cal/cm<sup3</sup>, unlikely to sustain.
U<sub>2</sub>Zn<sub>17</sub> = 530 cal/cm<sup>3</sup>, unlikely to sustain.
And of course ZnS = 1210 cal/cm<sup>3</sup>
I found a patent specifically on PdAl & PtAl fuse, check US patent #2911504. Though it sheds no more light on it then what is already known, only
mention of burnrate is "instantaneous", must be pretty fast if done right.<br>
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