May be better route to go will be to carefully oxidize the commercial nanosize aluminum particles.

First of all you should know what powder do you want to mill? If you use coarse powder (or consisting of hard agglomerates) it will be extremely difficult to disperse it to nanoscale. Second is what mill do you use? Such purpose required high-energy mills (planetary mill or attritor). And water is not a surfactant, try to use polyacrylic acid (dispex,darvan) or something like that.

On the over hand, when you will drying the suspension particles will aggregate to compensate surface energy. So, may be better to use unhydrous alcohol as milling media.

I do not have experience on aluminum, but you can try by doing a previous milling with same material to be grind, mill and let jar covered with that aluminum, then mill Al powder with your surfactant. Did you consider to use a different surfactant also?

If you try, let us know results, please

We have milled different oxides from micron-size powder up to the nanoscale (below 20 nm) using a "planetary milling". The milling parameters were similar

Speed (rpm) 300 rpm

BTP (ball to powder ratio) = 7:1 (7 gr of balls for each 1 gr of powder)

time = always above 30 h

In our case, we stop the process each 6 min and wait 3 min before start again to avoid an enhancement of temperature inside jars.

Regarding surfactant we usually use ethanol or nothing

It is necessary to take into consideration the milling conditions that may results to the formation of unexpected products. Milling speed and time taken during the milling are very important in regards to the products formed. Otherwise consider the use of surfactants as suggested above.

Unfortunately I am not concerned with the production of nanoparticles.

But from what I read aluminum nanoparticles can be obtained by ball milling method, but were shortly abandoned. More recent approaches focus on bottom up synthesis techniques such as physical vapor deposition, chemical vapor deposition...

Because of morphological structure. Forces between grains and macrograins.

Very good process for making aluminum, alumina or aluminim nitride particles is electric explosion of aliminim wires in argon with following passivation by oxygen.

Yes the method suggested by Sergei would be good. But one should have some back ground knowledge about alumina. Aluminum oxide exists in several phases, namely α, γ-, δ-, η-, θ-, and χ-Al2O3 . As the structure differs so the hardness. Also one should note that it is refractory material and used in as gems with little color dope of other metal oxide. The effort to grind that stuff to nano size will differ from phase to phase. It is better to oxidize simply by air a large surface of pure aluminum. A layer of aluminum oxide at the most of 4 nm will be deposited and further aerial oxidation will be stopped. A mechanical scratching would lead to the desired size of the alumina thus produced. Or one should go for bottom –up approach using chemical method where aluminum alkoxide may be heated under appropriate capping agent in high boiling solvent under air for the desired decomposition to alumina.

you have to avoid agglomeration. Darvan C, or beycostat C213 or similar.

what is the nature of "ball" and volume faction ?

I do have several experiences with many oxides such as SnO2, Al2O3, WO3, TiO3, ....Using planetary ball mill, the way that I use to grind them into nanoparticles is as follow:

1. Calcinate the powder inside a tube furnace (usually in presence of He or Ar)

2. Use different forms of media particles, 1 mm and 2 mm ceramic balls, and 1(d)x3(h) mm ceramic solid cylindrical if initial size of powder is less 100 um (if not you need a pre-coarse milling or grinding).

3. Use m-Xylene as media, leave the mixture in room temperature (not oven) to vaporize the media once the process was finished.

4. Fill the ball mill cylinder (100 mm diameter and 200 mm length) with media, media particles, and powder so that only one third of cylinder being occupied (Normally in this ratio 50ml media: 10 gr ball: 1.5 gr powder, for given sizes).

5. Rotation must be performed in both directions: CW and CCW. Use 80-100 rpm CW for 2 hrs, 10 min rest time, same rpm CCW for 2 hrs, 10 min rest time. Do the process for 36 to 40 hours (you need to program the machine).

6. After the media gone, calcinate the powder again and grind it inside an agate mortar.

7. Analysis the powders; either using particle size analyzer or TEM. 15% or less must lay above 100 nm, rest below than 100 nm mostly between 10 to 50 nm, good job!!! You did it...

See also this book: Electronic Materials and Processes, Chapter: Hybrid Microelectronic Materials and Systems, check the subsection for ball mill process.

Calcination or heating at low T ?

1) calcination above 600°C will increase grain size and phase transformation will start.

2) contamination with ball milling for long time

3)if you want to avoid grain growth during sintering (below 1000°C), you could stabilize γ- phase with dopant.

Thank you for the suggestion. I'm very appreciated

Dmitry Permin: FYI I'm using Alumina alfa phase -100 mesh 99% (sigma aldrich)

from SEM image the largest size is around 2 micron.

Agglomeration seems as the major problem because the milled powder tend to stick to the ball and jars. It became obvious when using small ball (0.2 mm) as proposed by manufacturer. Anyone knows the suitable ball size?

I'm planning to used stearic acid as a surfactant to avoid the agglomeration. Is it ok?

Other methods is not the solution for my case because my project focused on the high yield nanoparticles fabrication using ball milling method.

Razali,

Better you try with INERT ENVIRONMENT,. which may give you good result

Dear Razali, actually we did not solve almost the same problem (for over oxides) yet, but maybe you should use some sophisticated drying methods – freeze drying of spray drying. And, as I know, surface of high-disperse powder is covered by hydroxyl groups (especially after high-energy ball milling), so using calcined powder in non-water medium (absolute alcohol) the degree of aglomeration is ought to be lower.

And didn’t you think about bead mill? e.g. http://www.netzsch-grinding.com/en/products-solutions/wet-grinding/zeta-rs-nano-mill.html

yeah that why after milling the zeta potential become highly negative. however buy washing several time with water can make it positive. The main problem is to get

Dillip Bisoyi. Do you think that inert environment will help reduce the particle size? Any reference?

first of all , I would ask you how many hours the ball milling takes? some times u need 50 hours to reach nanoscale.

also after ball milling use sonicator for 2 hours.

don't use water with ball milling

Najlaa Alharbi : It take 20 hours.. What is the best surfactant to replace water?

Alumina is one of the most hard materials available. So actually a good change that you are grinding the milling balls instead of your powder. Use a plastic jar and acidified water to stabilize the particles. The only milling bead you should use are are made of alumina, this in order to avoid contamination of your product with material from the milling beads. All in all milling can take up to several weeks using a rolling bench which turns relative slowly, ensuring the bead roll over each other in the jar. High impact milling can also provide enough energy to fuse particles together again.

I think some one get much more informations in the following web links:-

http://www.ncbi.nlm.nih.gov/pubmed/17252826

http://onlinelibrary.wiley.com/doi/10.1111/j.1151-2916.1996.tb08731.x/abstract

Thank you

Dear all,

I have figure out that the ball milling belt for the bowl was broken.

so annoying..

For physical grinding, use a bead dispenser to load your vials and plates with your desired amount of beads.

Here is a bead dispenser that I work with. Also using a large number of samples. LabTIE also has a large variety of Bead dispensers, fitting tubes, vials, 96-well 384-well etc.

https://www.labtie.com/seed-bead-powder-dispensers/112346-bead-dispensers

https://www.labtie.com/seed-bead-powder-dispensers/112346-bead-dispensers