Okay Guys,
Is there a good way to tell the difference in Aluminum or Magnesium scrap? I think I have aluminum but I'm not totally sure. I bought some transmission tails and valve covers the scrap place said were aluminum. I just would like to know if there is an easy way for me to tell the difference. Thanks for the help Ron

Magnesium is "HIGHLY FLAMIBLE" carefully take a small piece and hit it with a torch. If its Magnesium it will "Caution, very, quickly burn.

Aluminum will not react to simple flame, it will only melt with enough direct heat.

Alan T.

Magnese will feel more 'brittle' than alum, and will be 30% lighter.

And will burn.. :D

'Rekd

BTW, if the tranny tails are off a VW, it's magnese..

'Rekd

Ya, it'll burn very hot and water will not put it out! Make sure you are in a well ventilated out doors type area and don't look at it burn.... it'll leave spots on your eyes for day and may cause perm eye damage.

lsfoils wrote:
<<...and water will not put it out! >>

In Navy fire fighting training they told us that water on burning mag would cause an explosion. Something about the chemical reaction producing hydrogen. The "only" way to extinguish it is smothering.

robotic regards,

Tom
= = = = =
"Time's fun when you're having flies."
- - Kermit the Frog

Ya, I remember this being described as one of the ways to "burn" water. It gets so hot that the water molecule "cracks" into its basic elements, oxygen and hydrogen....

Thanks to all for the suggestions. I can cut a small piece off with a saw and test it with the torch on a sand pile. I just sometimes don't feel comfortable taking the word of a guy in a scrap place I don't know, especially with something like this that could cause lots of damage if I get it wrong. Some call me paranoid, I like to call it being able to live to a ripe old age. Thanks Ron

Don't consider yourself paranoid. There's a very thin line between brilliant and stupid, as well as success and failure. Caution is mandatory.

'Rekd

Hi Matt,

Maybe this would be a good time to suggest a Safety Forum...

Good suggestion. A safety forum is a great idea. I have never machined Magnesium but I did use a bar of it years ago. We shaved tiny slivers of it off the bar and used to build fires when camping. The only way to kill a piece of burning Mag. is to throw dirt on it and smother it out. Water is a definate no=no.

Alan T.

GREAT idea! I'll set one up tonite.

Thanks!

'Rekd

WOW!!!!!!
That one just slipped past us all.
Great idea!!:p :p

PEACE:D

Wow,
This is cool, a group of people who think like I do, safe is better, thinking ahead is good. Glad I could ask a question that inspired a new forum that was needed. Ron

Were all here. To help and be helped.


PEACE:D

Originally posted by lsfoils
Hi Matt,

Maybe this would be a good time to suggest a Safety Forum...

Done!

Don't ignit magnesium! If you haven't already anyway. It will not be put out by any means other than the exhaustion of fuel. Sand only makes it a little less dangerous. There is a chemical that you can buy from the pharmacy, you put a couple of drops on the material and if it turns grey it is mag. I'll try to find the info on it if anyone is still interest...still has any skin.

Hobbiest,
That would be good information to know. If you remember what chemical it is please post it. Thanks Ron

Here is the info for telling whether aly or mag. Magnesium is distinguished from aluminum by the use of a silver nitrate solution. The solution does not react with aluminum, but leaves a black deposit of silver on magnesium. Magnesium is produced in large quantities from sea water. It has excellent machinability, but special care must be used when machining because of its low kindling point. Knew I'd find it sooner or later!

Hobbiest,
Thanks for the info.
Ron

Find the volume of the part by putting it in a cylindrical waterbucket. Measure waterlevel before and after the part is in. The difference is the volume. Then weigh the part. You can now find the density. Al is 2.7kg/liter and Mg is 1.6kg/liter. Safe and simple.

Best regards

John

Too many pieces to that puzzle though. Silver nitrate is easier, and just as safe.

Originally posted by motordude
Find the volume of the part by putting it in a cylindrical waterbucket. Measure waterlevel before and after the part is in. The difference is the volume. Then weigh the part. You can now find the density. Al is 2.7kg/liter and Mg is 1.6kg/liter. Safe and simple.

Best regards

John

LoL, damn engineers! ;)

'Rekd

Ha!!

magnesium also rusts nearly instantly with conyacy with water

magnesium also rusts nearly instantly with conyacy with water

how do they keep mag wheels clean?

robotic regards,

Tom
= = = = =
"Here's champagne to our real friends, and real pain to our sham friends"

Real Mag wheels are basically magnesium.
The normal mag wheels used on cars are not magnesium but aluminium with a small (few %) of magnesium.

Great use for a magnesium stick is to use it in your iron casting project. Using its high burning temperature to set off "termite" mixture of iron oxide and aluminium powders

A combustion reaction is often an oxidation and reduction reaction. Since the oxidation of one substance involves the reduction of another, this type of reaction is often called redox reaction. In the following reaction,

2 Al + Fe2O3 = 2 Fe + Al2O3
The element Al is oxidized, but Fe is reduced. This reaction is also called a displacement reaction because Al displaces Fe in the oxide.


Using ordinary rust with aluminium powder you can quickly get melted iron. Of course there are many issues related to such quick reaction but it is hell fast.

Of course the Fe2O3 and Alum powder have to be very fine to be of any use, I have seen this experiment on my chemistry class in high school and it was terrific. After a bright light of the magnesium stick a red stream of hot iron precipitated in a sand bucked located below.

The aluminum powder needs to be REALLY fine though. Aluminum shavings from milling will not work

Termite powder (iron oxide & aluminium powder basically) normally is started with a magnesium cord, other heat sources are not enough hot...

Be careful burning metalic powders.
Depending upon the particle size (surface area to volume or sav) you might get a particle size which may go beyond a slow or quick burn rate.
The rate of reaction is reportedly far greater than the sav, the rate of reaction is inversely proportional to the particle radius,but by an exponential amount.
A really fine particle has much more surface to burn its relatively small mass.
In other words ,"KABOOOOM!!!!).
A little variability one day may cause something unexpected.
But now you might expect it!
By the way, some early rocket fuel consisted of powdered aluminum and diesel fuel, some solid fuels may also incorporate powdered aluminum.
-Mark

I seem to recall reading somewhere that if you put a few small drops of distilled white vinegar on magnesium it will bubble furiously while aluminum will do nothing. I'll have to check to be sure.

Some many years ago some magnesium found its way into a very large (30ft high) camp fire. Magnesium was a nose wheel from a cargo plane that failed xray testing. Weighed about 80lbs. When it finally got started it burnt the entire fire down to ashes in about 10 minutes. Anyone venturing closer than 30ft or so got sunburn and some lost eyebrows. As it was at night it was seen by aircraft and reported as a flight hazard. Everything looked like one continuous flsah from a camera - for half an hour. The fire brigade arrived and tried to bury it in sand. It didn't kill it, just turned the sand to glass. In the morning the hole was about a foot deep, four feet round and glazed.

Anyhow; magnesium rings far less than aluminium so its usually easy to detect by ear if you've got a known bit of Al, magnesium damps sound much better than Al. Magnesium is noticeably ( 1/3rd) lighter than the equivalent volume of Al. but is far harder to dent. The corrosion is different too. Al forms a relatively flat corrosion layer, even in the presence of salt, Magnesium will form high powdery white growths. If the mag has a surface finish the Nitrate test doesn't work so make sure you cut back to the metal base before testing it. If its a pure mag alloy like used in wheels or gearboxes simple pool or battery acid will bubble on clean mag. where it would not on Al.

Andrew

OK throwing all caution to the wind, and with a great deal of stupidity, you can turn your hot pot of castiron into good quality steel be .........yes you have guessed throw in a chunk of magnesium.........better also learn how to run....very fast too.....

wont catch me doing this

Hello,
the only way you can turn castiron into steel is to remove the carbon. Castiron has more than 1,2%C (if I remember correctly), Fe with less C than that is steel.
When introducing Mg in the castiron melt you get nodular cast iron, which is a very tough cast iron.

Regards

John

Hi John,
I thought that by adding magnesium to molten cast iron the effect of superheating the iron burnt off the carbon in the iron. the following passage gives full details.

Gray iron is brittle but soft and easily machined. White cast iron, or white iron, which is harder and more brittle, is made by cooling the molten iron rapidly. The carbon remains distributed throughout the iron as cementite (iron carbide, Fe3C). A malleable cast iron can be made by annealing white iron castings in a special furnace. Some of the carbon separates from the cementite; it is much more finely divided than in gray iron. A ductile iron may be prepared by adding magnesium to the molten pig iron; when the iron is cast the carbon forms tiny spherical nodules around the magnesium. Ductile iron is strong, shock resistant, and easily machined.

which means your are almost right, and more right than me!!

Regards

Roger

Hello Roger,
thanks for your reply. Again, adding Mg does not remove any carbon from the melt, it only changes the shape and distribution of the graphite. To remove carbon, one needs to add oxygen (O2). The O2 dissolves the carbon and leaves the melt as CO or CO2. The Mg causes the graphite to grow as spheres, where as in "normal" castiron the graphite grows as flakes. It does not remove any carbon in the process. The Mg is vaporised and the vapor travels throught the melt and lowers the sulphur content and promotes formation of spherodial graphite.

regards

John

Most domistic trans cases are Aluminum but REKD is right VW heads are ok mag usualy turns almost black from weather I heard of a guy sanding on a VW case to pretty it up and his shurt was filled with the dust and he made a spark when he hit a stud in the case and he lit up like a road flare to make mater's worse the polister shirt shrinkwrped him the chips from milling do make an exelinte distress flare. There are a lot of nice castings in the scrap thies days. alot of aircrart castings are also Mag

Ok, sorry guys, but I had to register to say this.

I was laughing at this thread when I saw this......
I seem to recall reading somewhere that if you put a few small drops of distilled white vinegar on magnesium it will bubble furiously while aluminum will do nothing. I'll have to check to be sure.

All other amusing methods aside, that is indeed the easiest way to test. Its pretty much standard practice in welding; an "old welder's trick" of sorts.

Just put a drop on the metal; if it foams it's magnesium, if nothing its aluminum.


Cheers, I'm off to read more about ball screws.......
:cheers:

When I was in the Army,I saw a guy set a Thermite grenade on top of a V-8 engine block and pull the pin.About 15 seconds later,it dropped on the ground.I was impressed.At one time,thermite was commonly used to weld thick iron sections.I really don't think it would be an economical method of melting iron for casting.Not sure what is in that massive white cloud of smoke either but,I am sure it is not healthy to breathe it.

BTW, if the tranny tails are off a VW, it's magnese..

'Rekd

Not always. Original (very old) transmissions and engine blocks from VW were an aluminum/magnesium alloy. Later air cooled models (around 1970 comes to mind) they started hasing out the magnesium. One needs to be really careful though because automakers are starting to reintroduce magnesium to reduce weight and vibration/noise in certain parts.

This was one of the few posts which held my attention straight to the end!
Well done!

Eric

Given all the interesting talk on burning metal powder some may be interested in http://en.wikipedia.org/wiki/Thermite especially some of the links to videos/pictures towards the bottom.

Okay Guys,
Is there a good way to tell the difference in Aluminum or Magnesium scrap? I think I have aluminum but I'm not totally sure. I bought some transmission tails and valve covers the scrap place said were aluminum. I just would like to know if there is an easy way for me to tell the difference. Thanks for the help Ron
Yes there is a very good and safe way to tell the difference between Aluminum and Magnesium. Place a small drop of Duzall Flux on the piece in question. If the remains clear it is Aluminum. If the drop turns jet black it is magnesium. Duzall is liquid flux used for soft soldering. It can be obtained from most welding supply houses. Duzall is a trade name of the Esab Co.
This stuff is not expensive comes in a small plastic bottle and is acid based, so be carefull with it. Handle it with the respect that any acid needs.