Tungsten magnetism 2

[metman]

Tungsten is ferromagnetic meaning essentially it is naturally magnetic.

There is a link on the

http://www that

talks about a scam(s) of Gold plated Tungsten being sold as Gold Bullion.

I will provide that link later if possible because I inadvertently deleted the email containing the link.

Within the thread there are different suggestions for testing to determine if a bar or coin is actually pure Gold or plated Tungsten.

The idea of using a magnet sounded best to me – not that I have any Gold, it is all academic to me – until someone said there are 4 or 5 different classes of Tungsten and two of these classes have NIL magnetism.

I responded by asking what was meant by classes of Tungsten since it is an element. Maybe if it is alloyed with small quantities of alloying elements with little effect on density, magnetism can be reduced or eliminated?

I am not interested in other test methods such as density because there is only 0.16% difference in density between the two metals and volumetric measurement is therefore a problem even using a Acrylic tube filled with water and insert the “Gold” bar endwise. Ultrasound can be used but the equipment is not inexpensive, etc, etc.

What is the effect of small additions of alloying elements on the ferromagnetism of Tungsten? How small is small you will ask and so will I ask.

 

[metman]

http://news.coinupdate.com/largest-private-refinery-discovers-gold-plated-tungsten-bar-0171/

 

[Ron]

I doubt that the tungsten has enough magnetism to be picked up by a permanent magnet. I would use a needle compass to detect it....much more sensitive than a magnet.

 

[IRstuff]

Duh???

The tried and trued test for gold, as indicated in many a movie, is to bite down on it. Gold and tungsten have RADICALLY different hardnesses.

As for magnetism, that'll probably depend on whether is been allowed with something else. I have some "tungsten" weights, possibly alloyed with steel, that are VERY attracted to a very strong magnet.

TTFN

FAQ731-376

 

[metman]

Yeah but if it is Tungsten ya might break a tooth!

 

[berkshire]

Forged, as in forgery, gold bars have been around for thousands of years, they were the driving force that inspired Archimedes to come up with the principal of specific gravity.
Tungsten bars, gold plated, have been known, the ones that they have discovered that is, for at least the last ten years.
One thing that cannot be gotten around is the tremendous difference between the melt temperature of gold and tungsten.
If there is any doubt about the veracity of a particular bar, take it to a refiner and get it recast.
B.E.

 

[metman]

...that'll probably depend on whether is been allowed with something else.

IR, are sure that is allowable? Heh heh

 

[ultramat]

Here are some additional information about magnetism and classes:

Tungsten alloys come in different classes. You can see a detailed description here:

http://ultra-mat.com/site/products/refractory-metals/tungsten

In the table you will see the properties of the different tungsten alloy classes. Pure tungsten does not have classes by the way.

Please see the following example:
1)
90% W
6% Ni
4% Cu
is listed as tungsten alloy class 1 and the magnetic properties are NIL because it does not contain Fe.

2)
90% W
6% Ni
4% Fe
is listed as tungsten alloy class 1 and the magnetic properties are Slightly magnetic because it does contain Fe.

I hope this is helpful.

 

[metman]

Thank you ultramat,

That must be the answer.

So then if it were the nil mag class of plated Tungsten alloy, it would be approximately 5.5% less dense than Gold and therefore could be reasonably found as fake Gold using specfic gravity.

If the specific gravity looks good (100% W or Au) and Ron's compass needle does not wobble it probably is Gold.

Maybe we should see if Fort Knox will melt down or not. Might as well -- the economy is about to melt down.

 

[metman]

Just in case you want to buy some Gold Bullion:

You can test for fake bars without having to damage the bar with ultrasonic testers. Below is a quote the Perth Mint received from a supplier of them:

“The 1090 Flaw Detector allows you to look into the Bar for voids/defects as well as UT velocity which is determined the products elastic modulus i.e Tungsten Velocity is 5183-5460m/sec and Gold is 3,240m/sec. For example if you calibrate for Au then the testing Tungsten bar of the same thickness, the UT thickness would read approximately half the actual because of the speeding-up of the sound through the Tungsten.”

 

[rconner]

I'm not sure I'd bet the farm on being able to tell the difference on the basis of density!!

 

[metman]

rconner,

I heard that loud and clear and is why my tongue was in cheek when typing "...probably is Gold."