24 replies to this topic

[tajmiester]

Not if the aluminium if fine enough. Didn't you ever do the experiment in school with the Potassium, Sodium -> Aluminium etc put in a bath of water. If you scratch off the micro film of aluminium oxide (or powder it...) you get a pretty reactive metal.

Tris

[Stuart]

I cant remember. Probably. Couldnt you just put something else in the pan other than water like some linseed oil. Then just pour the lot over some fine mesh to seperate most of it off and then you got ready coated Al powder/fillings.


Stuart

[tajmiester]

Yeah, that might do the job but it depends on how fine the stuff coming out of the grinder is. You might find it difficult to separate really fine Al from oil, oil being quite viscous.

Tris

[Matt]

BigG just said add boric acid!!!

[BigG]

Matt, Boric Acid will not help to prevent the reaction Tris speaks about. I assumed he adds some nitrate into the water?.

Tris - The reaction should not happen. Even on very fine particles, there is a protective film. The reaction might happen when you repeatedly "scratch the surface", but in case you do it only once, and the film will be recreated when the al rotate through the air before it hits the water.

[tajmiester]

Your right. I was subconsiously thinking of ball milling the aluminium. When ball milling it, the aluminium is continuously being broken down and there is not enough oxygen to keep replenishing the oxide layer. If you only grind the Al once you shouldn't get this problem, unless you intend to ball mill it after.

Tris

[jman]

If you use the blender, do you think it'll dull the blades horribly?

- Jared

[alany]

Doesn't it [the grinding method] just fling water everywhere and contaminate the product with carbide/silica and the bonding agent? It can't imagine that a few percent abrasive in flash is a good thing.

[Arthur Brown]

Commercial Al powder is made by blowing a jet of inert gas thru a stream of molten aluminium and grading the product for size, flake is milled powder. Fine micro needles are made by pouring molton Al onto a rapidly spinning disc.

[BigG]

Doesn't it [the grinding method] just fling water everywhere and contaminate the product with carbide/silica and the bonding agent?  It can't imagine that a few percent abrasive in flash is a good thing.

Apparently not. One of our club members sent a sample of his grinded AL to a lab, it had virtually no contamination. I guess it does depend on the sanding paper, but the oxide silicon one seem to adhere amazingly well. As for water splashing everywhere ? you do need the balance, to fast and it?s water everywhere. To slow and you stall. There is a range in the middle that the water doesn?t splash.