Review of methods to make nanoscale powders

Apologies if this is in the wrong forum but can anyone suggest some references that provide a review of the different manufacturing techniques for making nanoscale powders?

I am particularly interested in:
1) Nanoscale reactive powders - e.g. metals, organic compounds
2) Production capacity estimates
3) Figures for cost per gram
4) Comparison of how the production method, capacity and cost increase as you go from micrometric to nanometric powders
5) Methods that have been tried but were unsuccessful

I am new to the field and just want more bedtime reading

I've tried searching for "review nano powder manufacture" on Google Scholar but it just turns up methods for making specific powders rather than a more general introduction.

Thank you, I am reading it now

I do recall a method of making nanoscale powders that involved sending an electric pulse through a wire suspended in an inert gas. The wire vapourises and nanoscale powder is produced.

Obviously not an ideal method if you want kgs of the stuff!

Yeah, it's really interesting, as it points out that these high energy mills are well capable of going all the way to nano. The major issue is the contamination.
Look at the graph where they milled aluminum powder to test contamination.
With stainless steel jar and media the %SS in the powder was 0.5% after 100 minutes and 1.5% after 1000.
While by using tungsten carbide jar and media contamination was 5% after 100min and a wobbling 35% after 1000! . It seems that harder isn't always better, as the WC really likes to chew itself up.

I've been checking out prices of these machines and it seems they go from $2000 and up .

But they shouldn't be too hard to build , the hardest part would be the planetary gear system, for which a machine shop is a must.

Some more stuff I found online:
They make 39-96 nm Al-Cu particles :

Attachment: 0312223627.pdf (271kB)
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An excellent paper with lots of graphs and pictures, making nanoparticles for use in nanofluids:
http://ethesis.nitrkl.ac.in/192/1/final_report.pdf

[Edited on 23-4-2011 by condennnsa]

Well this is just off the top of my head, after all, everything I know about this is what I've read here and there on the web.
1) I figure that a quenched metal would decrease more rapidly in size in the first period of the milling time, because it will fracture by breaking apart. While an annealed piece, being softer and more ductile, would have to be bent over and over, which will cause it to eventually break apart to smaller pieces, so I figure that it will decrease in size more slowly.
2) I don't know I guess so.
3) Well I'm as surpised as you, and I didn't notice that myself.
I really don't have an explanation. Maybe it has to do with figure 2 on page 3, some kind of agglomeration effect. I think this is also related to the material ductility, as until the particles acquire sufficient fatigue in order to break apart, they can agglomerate. Therefore, I would not expect such a graph for brittle materials.




Here is a contraption I've come up with for a high energy ball mill design which does not use planetary gears.
Hope my paint sketch is clear enough, it's basically a system which allows to rotate the jar while eliminating its movement of revolution, thus creating high centrifugal forces on the walls. Its actually the same as a planetary system, but less efficient since in a planetary mill the rotating and revolving directions are actually opposite.

[Edited on 23-4-2011 by condennnsa]

[Edited on 23-4-2011 by condennnsa]

Yeah you're right, it was only a sketch though to illustrate the mechanism.

With some math and adjustable counterweights i think it could be made to work... like so

I am really tempted to try to build something like this, to see how it'd work for blackpowder. I remember reading somewhere that high energy mills decrease the mill time for BP by an order of magnitude compared to conventional ball milling.




[Edited on 23-4-2011 by condennnsa]

Quote: Originally posted by condennnsa

Yeah you're right, it was only a sketch though to illustrate the mechanism. With some math and adjustable counterweights i think it could be made to work... like so I am really tempted to try to build something like this, to see how it'd work for blackpowder. I remember reading somewhere that high energy mills decrease the mill time for BP by an order of magnitude compared to conventional ball milling.

Yes this is starting to be more promising . You could even mount another jar symetrically so that the off-axis forces cancel out.

Why do you need a ball mill to make black powder? You can already get saltpetre and sulphur in powder form.

Charcoal powder can be bought off Ebay or you can try activated charcoal for water filtration. I think even a plain ball mill will be enough to break up the activated charcoal to a fine enough powder.

Quote: Originally posted by IndependentBoffin

Frankly I do not think it will cost USD$2000 to build your own planetary ball mill professionally if you pay a workshop to do it. Say 1 day's work (8h @ USD$25 = USD$200), scavenged motorcycle or car engine (you can buy very old ones second hand cars for say USD$300 and other parts USD$500 at most.

patents

Quote: Originally posted by IndependentBoffin

Why do you need a ball mill to make black powder? You can already get saltpetre and sulphur in powder form. Charcoal powder can be bought off Ebay or you can try activated charcoal for water filtration. I think even a plain ball mill will be enough to break up the activated charcoal to a fine enough powder.

Quote: Originally posted by Bot0nist

Just mixing finely divided carbon sulfur, and KNO<sub>3</sub> will not make a good black powder. It is necessary to ball mill, or at least pulverize in a mortar and pedestal for long hours to get individual particles of sulfur and oxidizer to become impregnated in the pores of the carbon.