Sciencemadness Discussion Board - Making metal powders

Making metal powders

plante1999 - 22-9-2012 at 04:22

In an home chemistry lab very often metal powders are needed. Example are Tin powder, Zinc powder or aluminium powder. In this thread I would like to discus about home chemist way to make metal powders from metal ingot. At the time I'm more interested to make tin powder, but many other metal powder's are used like aluminium powder for phosphorus production.

Thanks!

[Edited on 23-9-2012 by plante1999]

Hexavalent - 22-9-2012 at 09:58

I usually buy my metal powders, but for coarser stuff I get access to filings from the workshops (in the engineering department) at my school. This can probably be done in an amateur environment, e.g. filing down the ingot over a container. I have heard of people using blenders on aluminium, but how well that works and how safe it is, I've no idea.

LanthanumK - 22-9-2012 at 10:00

A file works well for creating small amounts of course magnesium or zinc powder.

kristofvagyok - 22-9-2012 at 12:01

Quote: Originally posted by plante1999

In an home chemistry lab very often metal powder's are needed. Example are Tin powder, Zinc powder or aluminium powder.

Pure metal powders are often hard to get, especially if analytical purity or any special grade stuff is needed.

The easiest way is usually go to the self and get the preferred stuff, or call Sigma and get a bottle of what is preferred

But I know that in a home lab this is aint so easy... So let's see.

I know someone who had made Al "powder" from Al foil with a blender. It wasn't at the quality of the "german black pyro Al", ut it was fairly good for flashpowder and thermite reactions. So this could be method no. 1.

Method no. 2 is also used in industry, it works with soft metals (even with Al), they make a relative large ball mills, they put a lot steel spheres in it and some of the metal what is need to milled. It will produce a really-really small grain size powder, the only problem that the steel spheres could spark and metal powders could ignite... So fill the ball mill with Ar or N2.

Method no. 3 could be electrochemistry, with well plated electrodes and proper current perfect metal powders could be made (powdered lithium is produced this way).

And my last method, no. 4 could be used for platinum, palladium, gold, ect. some metals could be reduced into metallic form from solutions with reducing gases like CO, SO2 and like these. With this method highly active metal powders could be made.

P.S.: method no. 5 also fits in the above category, because salts e.g. iron-oxalate could be reduced at elevated temperatures to pyrophoric iron.

elementcollector1 - 22-9-2012 at 12:13

Al: Possibly drill, cut ingot, ball mill result
Mg: Drill ingot, ball mill result
Less reactive metals: Chemical reduction of salts

phlogiston - 22-9-2012 at 14:01

For Al and Mg a somewhat common method among pyro's is to construct a device with a rotating drum pasted with sandpaper. The metal ingot is pressed against it. The drum is partially immersed in a bath of water or oil which prevents dust, keeps the temperature down, keeps the paper from clogging and in the case of oil provides some protection against oxidation.

kristofvagyok - 22-9-2012 at 14:24

My main problem with sandpaper was always that some "sand" will get into the metal powder what was made by that way. And the separation of a fine powder from a few percent of sand.... Nightmare.

elementcollector1 - 22-9-2012 at 14:31

Which is why the ball mill works so much better with turnings. I tried sandpaper for quite a while, and it was terrible. Hardly anything produced.

plante1999 - 22-9-2012 at 14:57

So in short we have at the time:

Ball mill for soft metal's like aluminium, reported to work very well.

A file for small amount of material, reported to work well.

Sandpaper, reported to work but give unpure metal powder, unsuitable for chemistry.

Coffee grinder/blender, reported to work but give coarse product.

(electro)Chemical reduction of noble metals, no report.

Reducing gas reduction of oxide, worked with iron oxide for me.

We need more ways and and more try at the procedures!

[Edited on 22-9-2012 by plante1999]

phlogiston - 22-9-2012 at 15:11

Not easily done at home, but possible if you are determined: another method is to pour the molten metal onto a rapidly spinning disc. It will spray the metal around and it will break up into tiny droplets that solidify in flight.
Other methods of atomizing molten metal are in use such as breaking up a flow of metal with an ultrasonic actuator or impinging a jet of pressurised gas onto it.

elementcollector1 - 22-9-2012 at 15:44

phlogiston, I don't think that's entirely within the reach of the home chemist, and potentially dangerous what with the molten metal, the spinning mist of molten metal, and the potential pyrophoricity of the result. Also, that produces spherical powders, whereas we think flakes are more suited to the task (having more surface area).

As for chemical reduction, it works better the nobler the metal is. For example, copper works extremely well in this process, as does bismuth. Sodium and magnesium, for obvious reasons, work poorly. Aluminum fares little better. Lead, tin, and indium would presumably give good results, having similar reactivity to bismuth.

Electrolysis: Only works well for a few different metals. Copper and silver work well. More reactive metals could be made by making the bath molten, but you'd have to keep the temperature below the melting point of the desired metal and above the melting point of the salt for it to even possibly work.

Ball mill: Good
File: Good, takes forever to get anything useful
Drill: Especially good in tandem with the ball mill
Sandpaper: Bad, impure result and takes forever
Coffee grinder: Good, useful for most demonstrations where an oxidation coating is not unwanted.
Blender: Not so good, only really useful for making smaller flakes (which can then be ball milled).
Chemical: Good, but only in certain cases
Electrochemical: Good if you monitor the bath each and every 5 minutes for a number of days until desired result is achieved
Reducing gas w/oxide: Never tried. Presumably, it would work well, but I can't say for sure.

gsd - 22-9-2012 at 17:09

1) Aluminum Paint is basically an emulsion of ball-milled aluminum paste is oil & resin. If oil could be leached out using a suitable solvent then you can have the residue as almost pure aluminum flakey powder.

2) Long ago I have read in physics text book that if tin metal is cooled sufficiently then it becomes so brittle that it just crumbles in a powder. My attempt to do so by putting small beads of tin metal in the freezer of our household refrigerator failed probably because the temperature (-20 Deg C) was not low enough.

There even was a story in that book about an expedition to the north pole was put to great inconvenience because tin in their soldered metal containers gave away due to extreme cold.

gsd

elementcollector1 - 22-9-2012 at 17:35

Yes, that's due to allotropy. One allotrope of tin is bright, shiny and generally more rotund, and the other is gray, flaky and not as nice-looking. Then, once the tin heats back up, it turns back into the other allotrope, while still very flaky. This could generate some nice tin powder. I don't think any other metal does this quite as easily, if at all. The Wiki throw states that pure tin will transform into this allotrope at 13.2 C, while impurities can lower this to well below 0, or make the transformation impossible. 99% Sn solder would be a good choice for this, I think.

UnintentionalChaos - 22-9-2012 at 17:46

Gray tin is a funny thing. While thermodynamically favorable below 13.2C, it needs a kick in the pants to start. There are some preps in Brauer, I believe involving ammonium hexachlorostannate solution. More typically, you just need to seed white tin with a bit of gray tin.

Small amounts of certain other metals also have powerful inhibitory effects.

Hexavalent - 23-9-2012 at 01:53

I have just read a report on preparing ultrafine copper powder by the reduction of copper sulfate using ascorbic acid as a reducing agent, and might try it soon. I'm on my phone at the moment so I can't provide a link, but IIRC it was by a researcher called Songping-Wu.

hyfalcon - 23-9-2012 at 03:08

Quote: Originally posted by elementcollector1

Yes, that's due to allotropy. One allotrope of tin is bright, shiny and generally more rotund, and the other is gray, flaky and not as nice-looking. Then, once the tin heats back up, it turns back into the other allotrope, while still very flaky. This could generate some nice tin powder. I don't think any other metal does this quite as easily, if at all. The Wiki throw states that pure tin will transform into this allotrope at 13.2 C, while impurities can lower this to well below 0, or make the transformation impossible. 99% Sn solder would be a good choice for this, I think.

Isn't this what caused Napoleon's troops to freeze to death on the march out of Russia? Their tin buttons crumbled allowing their clothes to pop open and the subzero winter did the rest.

Yo-Yo - 23-9-2012 at 04:25

This page (possibly from a member)
http://members.pyroforum.nl/gamekeeper/metal_grinding_machin...
Gives some good advice including plans and comparisons for a powder grinder.

Fossil - 23-9-2012 at 04:54

Quote: Originally posted by Hexavalent

I have just read a report on preparing ultrafine copper powder by the reduction of copper sulfate using ascorbic acid as a reducing agent, and might try it soon. I'm on my phone at the moment so I can't provide a link, but IIRC it was by a researcher called Songping-Wu.

Aluminium can also be used to displace the copper, downside is it takes a couple days. Once you're done, filter and wash with HCl to clean the copper of any oxide and remove any leftover aluminium.

Endimion17 - 23-9-2012 at 05:14

You can make large quantities of very fine iron powder by reducing its oxide using hydrogen. It works for copper, too, and I think many other transition metals in very fine mesh form can be obtained that way.
Sometimes carbon(II) oxide can be used, but hydrogen is easier to isolate. Be careful, almost all freshly prepared fine metal powders are pyrophoric. It's best to use a low quality cork for closing reaction tubes and just leave the powder for a few days. Traces of oxygen seeping through the cork reduce the activity of the powder's surface.

Many metals can be reduced using organic reducers in aqueous solutions, but then it's the concentration that dictates the mesh size, and it's not a quick procedure for making a lot of powder relative to the vessel size.

Iron and lead oxalate upon heating give iron and lead (and lead(II) oxide, but higher temperatures prevent large quantities from forming) so finely dispersed that their active surface is extremely large. Be very careful because if it catches fire, it looks like a piece of coal, glowing dull red. It's very hot. It's a metal on fire, so don't play with it.

Sodium can be dispersed by rapid cooling of vigorously stirred melt in kerosene (preferably in a closed, oxygen deprived atmosphere). The more intensive the stirring is, the finer the grains become. Ultrasound probes could disperse it into real powder. Of course, it would be extremely reactive and would be useful for organic chemisty, but under inert gas conditions. That's not something an inexperienced amateur should perform.
Stirring has to be done with an overhead stirrer, and not a magnetic one, because sodium is paramagnetic and will coalesce under rotating magnetic field.
I've made such fine grain before and because I don't have inert gas cyllinder at home, I had to resort to purging the vessel using kerosene vapor. Traces of oxygen exist in non degassed kerosene, so the product always looked dull violet-gray.

I suppose calcium could also be dispersed in a ball mill like magnesium, but I'd purge oxygen out using argon or I'd end up with calcium and quicklime powder instead.

Quote: Originally posted by Fossil

Aluminium can also be used to displace the copper, downside is it takes a couple days. Once you're done, filter and wash with HCl to clean the copper of any oxide and remove any leftover aluminium.

You can never get reasonably pure copper that way. You get grains that contain aluminium inside. It's always contaminated because once the aluminium grain is covered by copper, the reaction stops - its surface is sealed shut. Unlike hydrogen reduction of iron(III) oxide, the end product is not porous because its units are joined by metallic bonds.

However if aluminium poses no problems for future plans, it's fine.

[Edited on 23-9-2012 by Endimion17]

Copper powder

Mailinmypocket - 23-9-2012 at 07:32

Found this on lambdasyn. The page should load fine, it is translated with Microsoft translator.

bquirky - 23-9-2012 at 08:09

I have previously made tens of Kg's of powdered metals like copper and iron and even some nickle via the electrochemical route when i was playing with sintering.

The trick is to use an extremely small cathode to create a ver high current density on the surface. and run the cell at such a large over voltage (and subsequently large current) that there is very vigorous gas production on the cathode this will help the metal granuales fall off and keep the partical sizes small.

Ive have never tried this with zinc but id guess that with some agitation to break up the zinc sponge it would work quite well.

It may even work with Aluminium if a sutible electrolyte can be found.
I have tried with acetone/aluminium chloride and ethanol / aluminium chloride and managed to get a few ma to flow at about 20-30 volts i ended up with perhaps a half a gram of grey powder on the cathode. this fizzed when put into NaOH so it might have been Al powder.

I have allso reduced Copper Sulfate with brown sugar (I don't think there's anything special about brown sugar its just what i had at hand) I don't know the exact chemical reaction.

in a 200ml beaker
I created a hot saturated solution of CuSO4. added about 40 grams of brown sugar heated untill just about boiling then i added about half a gram of NaOH granules. the beaker rapidly fizzed up and turned bright orange.

the resulting copper powder after washing/settling and decanting several times was extremely fine and alittle conductive if pressed firmly.

bquirky - 23-9-2012 at 08:19

Oh incidently a few Kg of powdered iron in water will create a visible quantity of hydrogen bubbles that go's for days

I ment to make a h2 candle that worked that way but forgot bout it

elementcollector1 - 23-9-2012 at 11:24

I didn't think iron was reactive enough to produce hydrogen from water. Even magnesium only works at elevated temperatures.

Eddygp - 23-9-2012 at 11:33

I find the file suitable for small quantities. Reduction is a good option though.

platedish29 - 23-9-2012 at 15:58

Think about a 1" tubing, which at one end, on top, you plug a CO2 extinguisher tank, and at the other open end you put a flat closure with screw adpter. Screw the closure as to allow for the thinnest squeeze possible, in a preliminary test with water. Then do another test with molten lead. If successful, it will work for most metals in the melting range of your burner.

ldanielrosa - 23-9-2012 at 22:52

I'm taking the ball mill route. I have aluminum running now, but I'll attempt to powder some steel wool next. I'll let y'all know when it's done.

triplepoint - 23-9-2012 at 23:05

Quote: Originally posted by ldanielrosa

I'm taking the ball mill route...

I've been considering getting a ball mill. One of my concerns is noise. If I got a mill, I would probably build a sound-insulating enclosure based on one of the plans available online. What is your experience with noise from your mill and how do you deal with it?

phlogiston - 24-9-2012 at 01:38

I place a box covered with sound isolation foam over the container, and it dampens the sound rather well. With the mill in an uncovered hole in the ground with the box over the rotating drum I can only barely hear it 20m away.

phlogiston - 24-9-2012 at 04:06

Quote:

My main problem with sandpaper was always that some "sand" will get into the metal powder what was made by that way. And the separation of a fine powder from a few percent of sand.... Nightmare.

Actually, sandpaper is very often made using aluminium oxide grit.
If you are making aluminium powder there is going to be some oxide in it anyway, so the few additional aluminium oxide particles from the sandpaper probably make little difference.

[Edited on 24-9-2012 by phlogiston]

elementcollector1 - 24-9-2012 at 19:04

Yeah, but the hacksaw method produced bright, shiny flakes of powder. No contamination short of oxide layer on the surface.
I will have to see if my aluminum from foil actually works in thermite reactions, that will be a test for this weekend (ugh, college).

Bot0nist - 8-10-2012 at 17:25

It has been touched on in this thread, but never plainly stated. A very fine Cu powder can be had easily from copper pipings and such by first using them to make copper sulfate, either through electrochemical cell or through the action of a hydrogen peroxide/sulfuric acid soulution.

Make a concentrated solution of the prepared copper sulfate and add to it a pinch of NaCl and a few small strips of cheap Al foil. A rapid and exothermic reation will percipitate very fine Cu metal. If the solution is kept moderatly cooled and rapidly stired the powder will be finer and more consistant. Wash with warm water and dry for use immediately, or protect it from oxidation.

The powdered Cu is fine enough to produce a fast and beautifully bright flashpowder with KClO3 or KClO4. I doubt it is storage friendly, or even safe though.

hyfalcon - 9-10-2012 at 01:25

At least the powder mixes can be kept separately till time to use them. Some of these exotic primaries as has already been mentioned don't store well.

weschem - 11-11-2012 at 11:13

Has anyone tried putting a whole ingot in a ball mill to turn it into powder? If so how long did it take? Im currently building a ball mill out of an old bench grinder, steel rods, and a paint can. What kind of size particles have others been seeing?

elementcollector1 - 13-11-2012 at 12:17

Well, I've put aluminum chunks in the ball mill to help with milling and to possibly provide more aluminum. All I've seen is that they're getting shinier (I think the milling action is 'polishing' them).

As for size of particles, just by judging from sight the largest stuff was about 2-3mm in size after 4 straight days of milling, where the initial stuff had been somewhere around 5-6mm. The smallest stuff was too small to judge without a ruler, but I would hazard a guess at 400 mesh. Both the larger and smaller stuff were dark gray, as compared to the shiny stuff I put in there.

lead metal powder

platedish29 - 31-12-2012 at 17:09

Lead metal powder can be chemically prepared to a fine mesh from elemental lead.
1 mol lead, 2 mol acetic acid, make it to about 25% conc. of the acid into water. 100ml H2O2 "nothing" happens. Plus 150mL, vigorous reaction. Might be because of right dilution nut I don't think so.
The black powder left behind is Pb in a very fine mesh, not PbO2.
This will turn into PbO before melts.
Yield: for every 500g Lead, about 50g lead pwd. is left behind

Oscilllator - 31-12-2012 at 21:17

Dont displacement reactions produce fine metal powders? If so, they could quite easily be used to produce fine metal powders by the home chemist.

Hexavalent - 1-1-2013 at 08:23

Generally, yes. I imagine that the higher the temperature of the reactants, the finer the powder obtained; a higher temperature means a faster rate of reaction, which means that the metal particles have less time to form, and consequently are smaller in size (the same is true when growing crystals).

AJKOER - 1-1-2013 at 10:54

Quote: Originally posted by Bot0nist

It has been touched on in this thread, but never plainly stated. A very fine Cu powder can be had easily from copper pipings and such by first using them to make copper sulfate, either through electrochemical cell or through the action of a hydrogen peroxide/sulfuric acid solution.

Make a concentrated solution of the prepared copper sulfate and add to it a pinch of NaCl and a few small strips of cheap Al foil. A rapid and exothermic reation will percipitate very fine Cu metal. If the solution is kept moderatly cooled and rapidly stired the powder will be finer and more consistant. Wash with warm water and dry for use immediately, or protect it from oxidation.

The powdered Cu is fine enough to produce a fast and beautifully bright flashpowder with KClO3 or KClO4. I doubt it is storage friendly, or even safe though.

Here is a new (but perhaps too dangerous) way to similarly prepare Aluminum powder. Begin by forming a concentrated solution from slowly dissolving Aluminum in dry CH3OH. Source per Wikipedia (http://en.wikipedia.org/wiki/Methanol):

"One of the potential drawbacks of using high concentrations of methanol (and other alcohols, such as ethanol) in fuel is the corrosivity to some metals of methanol, particularly to aluminum. Methanol, although a weak acid, attacks the oxide coating that normally protects the aluminum from corrosion:

6 CH3OH + Al2O3 → 2 Al(OCH3)3 + 3 H2O

The resulting methoxide salts are soluble in methanol, resulting in a clean aluminum surface, which is readily oxidized by dissolved oxygen. Also, the methanol can act as an oxidizer:

6 CH3OH + 2 Al → 2 Al(OCH3)3 + 3 H2

This reciprocal process effectively fuels corrosion until either the metal is eaten away or the concentration of CH3OH is negligible."

Note, if someone could suggest a safer organic solvent, please comment.

One could add a few small Mg strips slowly into such a cooled organic solution (but certainly test this reaction first for safety and extent of the exothermic reaction while wearing appropriate safety gear in a ventilated environment). If the solution is kept moderately cooled and rapidly stirred, perhaps a fine Al powder could be formed. There is also the question of yield owing to the reaction between Mg and any CH3OH containing the Al(OCH3)3. Please see comments at http://www.sciencemadness.org/talk/viewthread.php?tid=20283

Bottomline: a not cheap, slow, toxic and still potentially a dangerous exothermic, but to some extent theoretically workable, path to fine Aluminum powder.

[Edited on 1-1-2013 by AJKOER]

elementcollector1 - 1-1-2013 at 10:58

Can you reuse methanol afterwards?

AJKOER - 1-1-2013 at 11:47

Can you reuse methanol afterwards?

My implied replacement reaction is:

3 Mg + 2 Al(OCH3)3 --> 3 Mg(OCH3)2 + 2 Al (s)

and, in my opinion, it is not wise to have significant CH3OH present so do not focus on recovering any alcohol. One reason is a potential reaction with the newly formed Aluminum reducing yield, which is to some extent reduced by a competing reaction with Mg:

2 Al + 6 CH3OH --> 2 Al(OCH3)3 + 3 H2 (g)

Mg + 2 CH3OH --> Mg(OCH3)2 + H2 (g)

However, the speed of these side reactions is reduced by the presence of water. But, Al (and Mg slowly) will react with water:

2 Al + 6 H2O --> 2 Al(OH)3 + 3 H2

While very dry CH3OH is needed to foster the initial reaction between Al (and Mg) and Methyl alcohol (or a little I2 or CS2 see http://pubs.acs.org/doi/abs/10.1021/ja01972a014 ), but the amount of H2O allowed into the system subsequently, is not immediately clear to me with respect to yield maximization.

I would start with using cheap watered down CH3OH (but at least 95%, see page 95 at http://www.biodiesel.org/docs/ffs-methanol/methanol-safe-han... ) and add a little Iodine and see if you can dissolve, even slowly, some Al. If successful, cautiously add with precautions some Mg strips with stirring. If any Al precipitate forms, quickly separate and protect especially from moisture.

[Edited on 2-1-2013 by AJKOER]

Metacelsus - 1-1-2013 at 16:05

Decomposition of certain carboxylic acid salts (such as oxalates and citrates) can produce extremely fine metal powders. The less active the metal, the better it works. For example, zinc oxalate decomposes to mostly zinc oxide, but iron oxalate gives iron powder. Don't even try it with metals above carbon in the activity series.

Keep in mind, fine metal powders can be pyrophoric.

bbartlog - 1-1-2013 at 16:26

Ferrous oxalate decomposes to a mixture of roughly half metallic iron and half FeO on heating, per Hurd (The pyrolysis of carbon compounds).

AJKOER - 1-1-2013 at 16:47

Here is a possibly safer experiment to form Al powder, but still expensive.

First, note that AlCl3 and MgCl2 are both somewhat soluble in Ethanol.

So, if one inserted a Mg strip in a warm solution of AlCl3 in Ethanol, one may be able to collect Aluminum powder.

Again, the presence of water may effect Al yield.

Also, the reaction between Mg and Ethanol is slow unless the Ethanol is heated to above its boiling temperature (78 C at atmospheric pressure: see http://www.freepatentsonline.com/6297188.html ).

However, the reaction of the newly formed Al and Et-OH in the presence of AlCl3 may be unfortunately significant. See "Corrosion Phenomenon and Its Analysis of 6063 Aluminum Alloy in Ethyl Alcohol" at http://www.jim.or.jp/journal/e/pdf3/50/06/1433.pdf where the Ethanol was 99.5%. Perhaps in slightly more dilute amounts, one may be able to achieve an acceptable yield of Aluminum as the presence of water impedes the Al/alcohol reaction.

[Edited on 2-1-2013 by AJKOER]

jock88 - 2-1-2013 at 10:49

Never heard this mentioned before.
One starting point for Al powder when making it with a ball mill is Al foil.
A better and far cheaper source of Al would be to obtain a wood plainer and plain some Al slabs. It states with most (electric of course) wood plainers that
they are capable of plaining Al.
Use the plain at the lightest setting to get as thin and light of shavings as possible.
Never tried it myself.

Fantasma4500 - 2-1-2013 at 11:27

Copper powder

as ive played too much around with HCl + CuCl2 i know that if you dilute the solution of CuCl2 (not sure if HCl is needed for this) and dump in a piece of aluminium (or some tightly wrapped aluminium foil) copper should start forming, and its also very fine and easy to get off aswell..
only problem would be the contamination of aluminium, but i guess more HCl could be added to react with the aluminium, and it could be rinsed with water, or even NaOH, as HCl reacts quite slowly with copper..

for magnesium powder with sandpaper method, ive got 2 things, just additions not really new things..

magnesium water anode, round, somehow set to spin, perhaps electrical screwdriver?

the other method where the sandpaper is spinning and magnesium metal is pressed down onto the sandpaper, i read that a weak solution (was it 5%?) of potassium dichromate was used along with water so that the magnesium wouldnt react with the water.

a method that SHOULD work for nano size aluminium, but not very easy to get running would be to vapourize aluminium (yes, bring it to a boil) and then cool the aluminium fumes down with liquid nitrogen, this is an idea that was illustrated on youtube, i dont know if it would work, but i know that nasa have nanosized aluminium powder (ALICE rocket motor project)
or at least they say its nano size.

oh also another thing on magnesium, ballmilling magnesium is said to selfignite if its ballmilled for long time without giving it air, making a weak but (obviously) extremely hot explosion when you open.
but that would be several days constant ballmilling without letting in air.

Simbani - 3-1-2013 at 05:21

There are many ways to make nanopowdered metals, like sol-gel, planetary milling, explosive forming and so on.
There actually is nanometric magnesium available, but I wouldn´t touch that stuff. It seems to be pyrophoric. BTW, you can buy nano powders from companys, it´s expensive but if one badly wants a few gram of 20nm Al, why not?

An easy way is to make nanometric (maybe down to 5nm) Fe2O3 or Fe3O4 particles is to dissolve ironII- or III-sulfate in distilled water and very slowly under strong magnetic stirrment adding very dilute (5%) ammonia solution. Do this in a old beaker and make a big amount, filtering and drying is almost impossible because this stuff is so fine.

Metallurgy -- brittle metals

Fantasma4500 - 22-7-2013 at 06:04

again i post about metals, dont know if chemistry in general is the place to post about this?

anyhow, what i have gotten in my mind is brittle metals, as we all know, finer particles = faster reaction

i got onto this idea by magnalium, an magnesium and aluminium alloy of 50-50 by weight, its melted together and colled down, powdered by various methods
the finished metal is so brittle that if you squeeze a chunk with pliers or similar it will powder, crumble and fly to all sides
this has an application in pyrotechnics, as 80 mesh for flares

to the main point: i looked up what this is called, its seemingly called 'Intermetallic' compound

it seems to be possible to make CuZn brittle aswell, both are hard materials and only copper can be produced easily in a fine powder, but zinc is harder to produce in fine powders
i couldnt find anything on this wonderful brittle metal alloy ''Roman yellow brass, CuZn''
as by proportions etc.

so im asking if any of you have heard anything similar to the properties of magnalium?
meaning, a very easy manufacturing of metal powders, to be reacted with anhydrous gasses and so forth

edit -- link to wiki site on Intermetallic

[Edited on 22-7-2013 by Antiswat]

bfesser - 22-7-2013 at 06:41

As it so happens, while trolling through old posts looking for good stuff for my <a href="viewthread.php?tid=25000">Topical Compendium</a>, I came across a few threads relating to copper powders. I haven't added them to the compendium yet, but here are a couple relevant finds:<ul><li><a href="viewthread.php?tid=2654#pid29059">Self-made Copper powder (fine precipitation)</a></li><li><a href="viewthread.php?tid=44">Reduction of copper(II) by fructose</a></li></ul>And these are already on the compendium:<ul><li><a href="viewthread.php?tid=23967">Pyrophoric copper: How?</a></li><li><a href="viewthread.php?tid=17619#pid222867">[untitled post]</a></li></ul>(I haven't added them yet, because I'm trying to fix the broken links and images beforehand.)

[edit]
peach reported pyrophoricity of copper residues left from destructive distillation of copper(II) acetate.
<a href="viewthread.php?tid=10948#pid201138">The Wiki method to copper acetate and distillation</a>

[Edited on 28.7.13 by bfesser]

SM2 - 22-7-2013 at 06:57

bfesser is right. In lieu of having the right, dedicated hardward, going for a colloid is the best, and the particle size WILL be very small. I've played with brittle metals and metaloids, both at room temp., and liq. N2. Usually I just get a fracture along the crystalline lattice. Some metals (like tungsten) and sometimes made into solid form by combining the W powder with a *tiny* bit of something else (which mostly escapes during the procedure), and applying great pressure and heat to the mass.

unionised - 22-7-2013 at 13:02

Trust me, getting brittle metals isn't always a matter of messing about with liquid nitrogen etc.
http://en.wikipedia.org/wiki/Zinc_pest

Fantasma4500 - 22-7-2013 at 13:57

well copper is pretty fairly simply as of what i have found it to be..
CuCl2 + HCl + Al
this also produces Cu(I)Cl which can be isolated as a tetraammine where the copper powder will be left as sticky bits in the filter

but for CuZn, the deal is not getting the Cu powder as its mostly not so reactive as the Zn powder
Zn powder can be reacted with S, i have even seen this confined so well that it gave off an actual bang, apart from this it has been used as rocket fuel
it can be used to generate H2S later on (ZnS + HCl)
but if this could be done with other alloys... as in using other metals, even lead, then you could get to very quickly react it to get fx. lead acetate in short time

also recall FeSO4 by CuSO4 + steel wool, in which coated the steelwool with wet copper powder which i got a quite neat amount of

Endimion17 - 23-7-2013 at 06:22

You can always heat zinc. It will turn brittle above 210 °C and you can smash it with a hammer.

12AX7 - 23-7-2013 at 19:33

CuZn doesn't really have a weak phase, as far as I know. Beta brass is white, hard, not very ductile, but as far as I know, tends to remain strong.

That said.. the most zinc-rich brass alloy I can find is 40%Zn "architectural bronze", which still has 20% elongation (not as ductile as common 30%Zn "cartridge brass", which is very ductile, up to 50% elongation, maybe even more).

Looking at the phase diagram, I see three intermetallics, corresponding roughly to 47%at, 63%at and 83%at. The latter suggests roughly CuZn5, the others aren't so specific. All of them have a moderate solubility range (even at room temperature), suggesting two things: the electronic bonding and atomic radii are similar (which is true), or the crystal structures are somewhat pliable (which tends to imply a tolerance for slippage and defects, i.e., properties which make metals malleable).

Don't think about Al-Zn: the system is an almost-simple binary eutectic, so all alloys range smoothly from soft zinc, to hard alloy, back to soft aluminum. No help there.

Mg-Zn, however, is useful similar to Mg-Al: there are several intermetallics, all of which have very little (solid state) solubility range. The plot shows Mg12Zn13, Mg2Zn3, a laves phase (MgZn2), and Mg2Zn11. I believe I once made some MgZn2, and it worked very nicely in a pyrotechnic composition: the bright blue-green of zinc, with a bit of extra reactivity thanks to the magnesium. (Any time you see a laves phase on a phase diagram, you can be pretty well assured it's brittle. They aren't necessarily weak -- I'm sure some among the refractory metals are more like cermets in performance -- however, this one you can reasonably guess is weak, given its moderate melting point.)

And, just for completeness, the Al-Mg system shows Al140Mg89, and gamma phase (around 58%at, with some solubility range; in this case, we already know it is a brittle phase, despite it having some range). Both are low melting phases, not much above the lowest eutectic (gamma MP = 736 K).

Al-Cu at 50%wt (i.e., ~Al2Cu) is quite brittle, but with so much (near-inert) copper content, I don't think it's too useful pyrotechnically or chemically. It is useful metallurgically, as it has a low melting point (slightly less than pure aluminum), so is a good way to increase copper content (i.e., a master alloy) in aluminum melts.

Tim

Fantasma4500 - 24-7-2013 at 05:37

thanks for the inputs
always saw it as being very strange to powder an such hard metal as zinc and sell it in that great quantities, is there any indications of when you have the zinc at 'brittle temperature' so to call it?
i did melt alot of zinc, and i saw it as being very mysterious, because some yellow surface formed on it (C2H2 and O2 was present if that would make a difference) i never found out if it was ZnO or what it was
burned with a blue colour like sulfur, but where would the sulfur come from? the link gave some clearness, got abit lost at it haha

one thing on these metal ratios, are these taken by grammes (Mg Zn2, 100g Mg 200g Zn?) or is it taken as molar ratios?
MgZn sounds like something that could potentially become very very useful, love the sparks and colours zinc gives myself, have dumped many handmade grammes of zinc dust into flames back in time

by what i see, magnesium is what holds these brittle intermetallic properties, perhaps it could be run together with something else..? ive seen them write about addind calcium and lithium metal in the range of 10% by weight, calcium seemingly to form a CaO surface that would stop it from burning

who knows, perhaps the zinc could completely take the all toxic barium's place in pyrotechnics if enough people were made aware of this?
i should perhaps tell some persons i know makes magnalium and such stuff at home and sells it in great quantities about this??
i am in fact going somewhere today to get to make some metal bars and such, so i will have a nice amount og zinc from wheel balancing pieces laying around for future testing of this

thanks alot, this is something i need to save (:

12AX7 - 24-7-2013 at 21:51

Zinc oxide is yellow when hot, white when cool (thermochromic). This can also be seen over molten aluminum alloys rich in zinc, for the same reason (7000 series zinc-bearing alloys are sometimes used in sheet, structural forms and extrusions).

I specified "%wt" when the percentage is by weight, or "%at" when by atomic (molar) ratio. Formulas are explicitly atomic ratio and need not specify. It will be illuminating to study basic chemistry and familiarize yourself with chemical formulas, atomic mass and calculating ratios by atom and by weight.

Magnesium holds no special powers, in and of itself; it is simply the luck of how the atoms fit together. For example, the laves phase requires two slightly different size atoms, and occurs very commonly in all systems with this property, even piles of balls.

I don't know of any Ca and Li bearing magnesium alloys offhand. I've heard of Al-Li alloys before, and Ca is occasionally used, for example to enhance the conductivity of lead, or (along with magnesium, which is more commonly used) to purify and modify iron alloys, mainly to make ductile instead of gray cast iron.

Zinc cannot replace barium because barium has a bright, pure green. Zinc exhibits two primary spectral lines, hence its varying description as some combination of blue and green: neither line is perfectly blue or green, and the ratio of the two varies with conditions, so that some parts of a zinc flame will be bluer or greener than others.

Copper might be a better candidate, having a reasonably green spectral line, but because cooler copper flames tend to be blue, the color would not be very pure, it would tend to be blue around the edges, or turn blue at the end. Blue is also most prominent in the presence of chlorine, a common ingredient in pyrotechnics as perchlorate for example. A green copper composition would have to avoid chlorine.

Tim

Fantasma4500 - 26-7-2013 at 04:41

infact my whole adventure for so far (but surely continuing later on) went pretty horribly wrong
couldnt get the first bit of aluminium to melt, zinc went fine, nothing yellow seen even
then i put on my much more thick ''steel'' container for getting the al molten
seemingly by the massive fireball that was VERY GREEN at daylight, with the smooth charasteristics of Zn + S somehow, it removed itself in the hot fire
it wasnt steel im pretty sure of
ZnO is yellow when hot, but wouldnt this effect stop when it cools down, because i recovered abit of the can that was somewhat blown apart, and im gonna test for what the hell that thing was, never seen zinc itself go off like that by pure heat, carbon and abit of air..??

the bottom of the beforehand assumed steel also changed colour due to heating, just like iron does, we did melt the zinc and cast it into a bar from that very container, possibly an alloy, even with magnesium in...?
the whole thing started and stopped burning in approx 0.2 seconds

never found anywhere about the atomic ratios, but now that you put it like that it seems too clear, just like you dont write H2O1 but instead H2O

actually one interesting thing about colours is CuCl2
i like CuCl2, so useful for so many things
anyhow about the colours, related to CuCl2, when its put in a fire it gives off both green and bright lightblue flames, i didnt know the temperature had effect on this however, that makes sense why it decides to sometimes give off green instead of lightblue
perhaps the blue is what gives zinc its characteristic green colour, one other thing, there was a sure but very faded smell of sulfur after the metal can went into a mushroom cloud, just further confuses me, could be that they alloyed actual sulfur in metal anyways

i think ill add rough temperature check of flames to my list of what you can use CuCl2 for, as when you have a dispersion of HCl and CuCl2 in a flask with hydrogen and you ignite it, the colour is PURE lightblue, no trace by any means of green, indicating a temperature thats low

another thing, do you know if it by the book (theoretically) would act more blinding if a bright flash was coloured bright green, rather than a less ''bright'' colour spectrum, or less easily detected such as purple or red..?
lately i was blinded by a 1:1:2 KClO4 Ba(NO3)2 MgAl giving a spot lasting for more than 10 minutes, only 5.5 grammes.. and i have had some serious blindings but this was first time i used Ba(NO3)2 in these kinds of things

subsecret - 29-7-2013 at 20:00

I've had pretty good experience with iron (II) oxalate. I recommend keeping it under an inert gas atmosphere (I used CO2, but I still need to get a drying tube for it). CO2 is not the best but it's better than air. Upon heating, the iron oxalate decomposes to iron and iron oxide (As mentioned earlier). Would keeping it under a better inert atmosphere keep the oxides from forming?

Iron (II) oxalate is rather easy to synthesize, and it's a good beginning experiment. I've done it several times myself.

http://www.youtube.com/watch?v=_2HHuUMkg58

That's a fantastic video for those who would like to attempt this experiment.

Pyro - 30-7-2013 at 12:48

A good milling media is a box of bullets, in the US you can buy all types of stuff for reloading bullets including the slugs. (front bit that shots out), If you buy FMJ's they are lead with a copper coat=no sparks. they come in boxes of 100 for something like 10$

[Edited on 30-7-2013 by Pyro]

AJKOER - 30-7-2013 at 16:13

On this forum, there has been prior discussion on the use of Ascorbic acid (Vitamin C) on CuSO4 as a path to fine metallic Copper (see for example discussion at http://www.sciencemadness.org/talk/viewthread.php?tid=2654 ).

Here is a reference ( "Preparation of Fine Copper Powder With Chemical Reduction Method and Its Application in MLCC" at http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=42... ) noting not only a path via CuSO4 and Ascorbic acid but also [Cu(NH3)4]++ and Ascorbic acid. To quote:

"In this paper, the preparation of fine copper powder with chemical reduction method was investigated. Polyhedron nonagglomerated monodispersed copper powders by the reaction of CuSO4ldr5H2O and ascorbic acid were synthesized at pH 6~7 and reaction temperature of 60degC~70degC. It was also found by X-ray diffraction (XRD) analysis that a mixture of copper and cuprous oxide could be obtained when [Cu(NH3)4]2+ was reduced by ascorbic acid. Reaction temperature and pH have great effects on efficiency and particle size of copper powders."

Now, this may present a larger number of alternatives to the home chemist as there are many available ways of forming [Cu(NH3)4]++ complex. For example, Cu + aqueous NH3 + H2O2, or Cu + aqueous NH3 + Na2CO3.H2O2, ....One can also prepare a convenient copper salt (like copper acetate from Cu/Acetic acid/H2O2) and add aqueous ammonia to form the royal blue copper ammine complex.

[Edited on 31-7-2013 by AJKOER]

bfesser - 30-7-2013 at 16:43

JKOER, I linked to that thread on page 2 of this topic (tl;dr?

). But thanks for finding that reference. I printed it out a few years ago while researching ascorbate redox reactions, but now that I see the title, I might be able to find it. A related paper is available for <a href="viewthread.php?tid=10601&page=28#pid142659">download in References</a>.

[Edited on 31.7.13 by bfesser]

Zyklon-A - 14-12-2013 at 09:42

I just made a ball mill from an electric mixer, but the problem is, it spins way to fast, it turns it into a centrifuge, and does not grind the Al at all.
I can't slow it down any more, but I might be able to add another cylinder to it and that would slow it down, right?

TheChemiKid - 14-12-2013 at 11:31

Here is a good video on how to make very fine metal powders.

bfesser - 14-12-2013 at 11:42

The video is alright, but the methods employed are labor intensive and far from ideal. For one thing, a file must only be used in one direction! They're only designed to work on a forward stroke of the file (reverse if you're holding the work piece); stroking it back and forth like that causes it to dull, clog, and work very slowly. A file is not a rasp! Second, it's probably easier to improvise a small ball mill—even hand-cranked—than to find a suitable steel plate and bar.

Pyro - 14-12-2013 at 11:59

that is an unbelievably labour intensive, wasteful and time consuming method.

grinding between those steel plates introduces all kinds of other metal oxides, and it spreads around fine Mg powder.

Just buy powders, If you can't, get someone who can to send some to you. I have more semi fine Mg powder than I will ever need, just U2U me.

Dornier 335A - 14-12-2013 at 13:15

As I have said many times in the comments of that video, it is only practical for making very small amounts of fine metal powders. For larger amounts I use, and recommend, a ball mill.
The method remains interesting though, because particle sizes not reached by a week of ball milling is achieved in five minutes. The process is faster and dust and oxidation is prevented by milling under a suitable non-polar solvent. I have for example successfully made nano-thermite with Fe₂O₃ and magnalium which explodes like the fastest flash powder.

thebean - 14-12-2013 at 18:14

For my copper I make a saturated solution of CuSO4 and drop some iron in there. You can substitute certain metals in this method. The other approach I use is filing metal ingots with a rat tail file.

Brain&Force - 14-12-2013 at 18:34

thebean, try adding salt and aluminum foil (or old drink cans) to your CuSO₄. That works a whole lot faster; plus you don't have to scrape copper off the aluminum pieces if they're sufficiently thin.

Zyklon-A - 14-12-2013 at 18:58

I think a hand-cranked ball mill would be more labor intensive video's method, but a electric ball mill would be great.

bfesser - 15-12-2013 at 07:02

Ever heard of gears and pulleys?

Zyklon-A - 15-12-2013 at 13:50

Yes, but I think it would time consuming to spin it.
Also, even with gears and pulleys, you cannot spin it too fast or it will no longer work, so you would still have to spin it a long time.
Plus installing a motor would not be that hard.

[Edited on 15-12-2013 by Zyklonb]

Mesa - 22-12-2013 at 10:35

I've made a few powders from alkoxides... It's not feasable for those on the higher end of the reactivity series, but for the quality and grain size I've gotten(despite sloppy labwork) it's been worthwhile to learn.

symboom - 12-12-2016 at 11:00

Maybe theres some way it can be made from metal foams
Which maybe brittle because of there structure

http://www.tms.org/pubs/journals/JOM/0012/Banhart-0012.html

https://m.youtube.com/watch?v=8FHTK2LZNTY

[Edited on 13-12-2016 by symboom]

AJKOER - 21-12-2016 at 09:30

Forming a metal powder increases surface area (and potential reactivity) at the expensive of structural strength. However, I vaguely recall reading about making an alloy and then dissolving the more reactive metal with, say, an acid resulting in the preservation of some structure.

The intended application, per my limited recollection, was electrode construction with the resulting structure providing good surface area.

More general applications are likely possible in other areas where surface area and a larger solid structure are appropriate.

Here is a reference to the apparent method referred to as dealloying, to quote:

"Dealloying or selective leaching refers to the selective removal of one element from an alloy by corrosion processes. A common example is the dezincification of unstabilized brass, whereby a weakened, porous copper structure is produced. The selective removal of zinc can proceed in a uniform manner or on a localized (plug-type) scale. It is difficult to rationalize dezincification in terms of preferential Zn dissolution out of the brass lattice structure. Rather, it is believed that brass dissolves with Zn remaining in solution and Cu replating out of the solution. Graphitic corrosion of gray cast iron, whereby a brittle graphite skeleton remains following preferential iron dissolution is a further example of selective leaching. The term ""graphitization is commonly used to identify this form of corrosion but is not recommended because of its use in metallurgy for the decomposition of carbide to graphite."

Link: https://www.nace.org/Dealloying/

For a recent review of the expanding field of dealloying and dealloying materials, see
http://www.annualreviews.org/doi/abs/10.1146/annurev-matsci-... .

[Edit] In the cited context of fine Zn/S powder, which as mentioned at the top of this page, can be explosive, the employment of a thin Zinc tubes created by dealloying surrounded by sulfur, I would expect a less explosive, slower and possibly more uniform, burn reaction. Related example, a burning Magnesium ribbon in air, except that the structure of the ribbon via dealloying, has been augmented to increase the burn rate.

[Edited on 22-12-2016 by AJKOER]

D4RR3N - 7-1-2017 at 17:25

A Carbide Rotary Burr File on a drill would work but its easier just to buy the powder.

TheMrbunGee - 19-1-2017 at 01:29

I made a video on zinc powder..

https://www.youtube.com/watch?v=bclTkQzd0Q8