On Thu, 14 Jun 2012 14:50:44 -0500, dpb wrote:

On 6/13/2012 11:31 PM, Martin Eastburn wrote:
Not marked on the rods ?

http://compare.ebay.com/like/3307387...pes&va r=sbar


Both look the same. Ugh.

Likely has to do with at what temp does one change magnetism.
Something simple like that. Or melting temp.

Get specifics of each rod and compare to spot a difference.
Test for difference.
...

There are differences in ductility and hardness owing to the differing
compositions but I doubt there's any way w/o an actual test rig to
determine the one over another at least w/o known samples for
comparison, not just a given single unknown sample.

Nickel's specific gravity is about 10% great than iron's; enough so
it'd be relatively easy to tell the difference between 99% Ni and a
55/45 alloy of Ni/Fe. But, copper's SG is very close to nickel, so I
think Monel (cupro-nickel) rod would be hard to dstiguish from 99% Ni
by SG alone. Weathered Monel can also have a grayish surface.

--
Ned Simmons

On 6/14/2012 3:38 PM, Ned Simmons wrote:
....

Nickel's specific gravity is about 10% great than iron's; enough so
it'd be relatively easy to tell the difference between 99% Ni and a
55/45 alloy of Ni/Fe. But, copper's SG is very close to nickel, so I
think Monel (cupro-nickel) rod would be hard to dstiguish from 99% Ni
by SG alone. Weathered Monel can also have a grayish surface.

If that were all that were in a typical rod, undoubtedly so.

Being so hot today I've given outside work up for a while, I looked at a
couple datasheets typical composition numbers and calculated a rod
density for the two...

D55=0.53*8.9+.45*7.86+.012*2.26+.007*2.33+0.003*7. 43
D55 =
8.3197
C55=.53+.45+0.012+0.007+0.003 % Ni+Co Fe C Si Mn
C55 =
1.0020
D99=0.85*8.9+14.5*(.08*7.86+0.02*2.26+.025*7.43+.0 2*2.33
+.025*8.96)/16.5
D99 =
8.5583
C99=0.85+14.5*(0.08+0.02+0.025+0.02+0.025)/16.5 % Ni Fe C Si Cu
C99 =
0.9994
D55/D99
ans =
0.9721


The ratio of the two is within 3% owing to the Cu+Mn primarily in the 99
bringing up the weight more than their "fair share" in comparison. The
datasheet was min/max (Ni/others) so the 14.5/16.5 factor is to bring
the total composition fraction to roughly unity; otherwise the
percentages sum to 102%.

The "C" values are sanity checks on the percentages...

So, undoubtedly could tell if had two to compare side-by-side, still a
little tougher to decide if the difference one is seeing is the rod
difference or a possible variation in composition between vendors...

I hadn't tried to compute before but thought it might work out even
closer overall before than this estimate so didn't suggest
weight/density as a reliable distinguisher, either.

--

"Ned Simmons" wrote in message
...
...

Nickel's specific gravity is about 10% great than iron's; enough so
it'd be relatively easy to tell the difference between 99% Ni and a
55/45 alloy of Ni/Fe. But, copper's SG is very close to nickel, so I
think Monel (cupro-nickel) rod would be hard to dstiguish from 99%
Ni
by SG alone. Weathered Monel can also have a grayish surface.

Ned Simmons

I haven't found a simple chemical test yet. If you dissolve a piece in
nitric acid and add ammonia the iron will precipitate out, FWIW.

Maybe someone with known samples of both could try a grinding spark
test?

jsw