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14th July 2010 22:44
Alan,
I am wondering if anhydrous boric acid (B2O3) would make a good blanket for your melt. Heating boric acid to about 450 C converts it to a nice clear flowable glass. It is quite inert, and was used for semiconductor ingot production in the early years.
I suspect that might be useful in attempting to make Magnalum shot as well, by pouring blanketed melted MgAl into an excess of molten B2O3--especially if the MgAl melts at a higher temperature. Got any idea of the MgAl melting point?
On the other hand, the B2O3 might give up its oxygen in a spectacular fashion, so I would try this in very small quantities...with eye, face, and hand protection, of course.
Regarding commutation (sp.?), put it in liquid nitrogen, LN2, and quickly strike it.
Your comparison to obsidian is interesting, and I suspect LN2 will enhance the frangiability by great degree.
I love your hobbies. They are very close to those of mine when I was a young man...
PilotDave
Inorganic Chemist, Lancair IV Builder and Pilot, Pyro Enthusiast, Early supplier to the single-crystal, microchip and fiberoptic science.
"There are old pilots and bold pilots, but there are very few old bold pilots"
Have you seen Skylighter.com new e-book pyro making books? They are well-designed.
8th July 2009 23:07
Michael,
I got a large ingot from a scrap metal merchant quite cheaply.
Smaller bits and pieces I've got from eBay and scrap merchants. It is quite cheap in large quantities of uncontrolled purity. You can get a fair idea how pure it is by measuring its density. For pyrotechnic purposes if you can burn a sliver shaved from it then it will probably be fine.
Regards,
Alan
8th July 2009 09:46
Hi Alan, I was wondering where you get your magnesium from?
keep up the great work!!!
9th December 2008 12:23
Sara,
Are you sure it is Magnalium? That's an odd material to make a kettle out of? If it is Magnalium it is probably mostly Aluminium otherwise it would be very brittle.
You can probably clean it with Bicarbonate of Soda made into a paste with water, but being alkaline and somewhat abrasive it may dull any polish it might have (try on an inconspicuous place first). You can try weak acids like vinegar or lemon juice, but they won't help shift the grease. You can always re-polish it with Brasso or a similar polishing compound.
Regards,
Alan
9th December 2008 04:28
I have a tea kettle made of magnailium and wonder if you could tell me what I can use to clean it up? It is pretty dirty with some old grease baked on and I'd like to get it clean without ruining it. Thanks for any help.
27th January 2008 03:47
On the note of ammonia... possibly magnesium nitride reducing water to produce ammonia and magnesium oxide? If I recall rightly, magnesium reacts with N2 almost as happily as it does with O2, so it wouldn’t seem to be a stretch to suppose that you had some nitride formation...
24th December 2007 23:34
I am unsure of the exact chemistry, but it seems plausible that it is the result of a reduction reaction.
24th December 2007 16:49
I too have noticed ammonia formation when MgAl comes into contact with water. Do you know if this is possibly due to the Mg oxidizing and leaving the N and H to bond?
23rd December 2007 13:33
Unfortunately there is no easy way to reduce bulk Magnalium metal into a powder. Its brittleness makes the comminution process slightly easier than with ductile metals like Aluminium, but it still involves slow mechanical means.
Granular material can be produced just be smashing Magnalium up in a iron mortar. A big hammer, a canvas sack and a concrete slab is useful for the roughing process, but once you have things below a rock-salt size the process becomes madenly slow and is best achieved by an automated machine.
A hammer mill could be constructed to do all the hard work, bit it would be quite noisy. I've managed to make small amounts of ultra-fine Magnalium powder by ball milling granular material with commercial Aluminina deburring media designed for lapidary use. It took about a week with a pretty low yield passing 325 mesh, but produced some of the most frighteningly dangerous flash fuel I've ever used short of micron-Magnesium.
Manual comminution is generally sufficient to produce material suitable for glitter compositions. That's the price you pay for your art if you can't purchase pre-milled material commercially.
Things not to try: Coffee grinders. I half-destroyed the blades in a coffee grinder trying this (and finished it off sometime later with FerroSilicon). Magnalium is extremely hard and easily erodes the blades in seconds. It also produced quite a fireworks display inside the grinder, so I stopped it very quickly only to find half of the blades gone! A metal-fuel air explosion might occur with larger machines, the energy output (and shortwave light!) would be not something you'd like to experience first hand.
23rd December 2007 04:43
i want to know how to make magnalium powder
16th July 2010 11:20
John Dunk wrote...