Rich Grise wrote:
Ned Simmons wrote:
On Sat, 19 Feb 2011 19:37:27 -0800, Rich Grise

Of inconel and hastelloy, which would be closer to plain ol' ordinary
nichrome, like you'd use in a heating element?

All three are families of alloys that cover lots of territory. If you
pick a specific nichrome alloy you do a composition search on Matweb
to find the closest match.
http://www.matweb.com/search/CompositionSearch.aspx

Thanks! I have numbers here that I can look up. Probably should have,
but that isn't anywhere near as much fun as asking real live people. :-)

Speaking of looking stuff up, I looked up "resistivity of nichrome" or some
such, and this website came up; is this guy an idiot or what? I'm only an
electronic tech, but I've never seen such bull**** presented as fact:
(well, I have, but that's an entirely different thread. ;-) )

----------quote--------
Resistivity is a measure of how strongly a material opposes the flow of
electric current. Good electrical conductors have very low resistivities
and good insulators have very high resistivities. Resistivity is denoted by
the Greek symbol rho (?) and can be determined by rearranging this formula:

R = ?l / A

where ? is called the resistivity of the material, R is the resistance, l is
the length and A represents a cross-sectional area. The unit of resistivity
is then ohm-meters (?m).

Nichrome, a non-magnetic alloy that is commonly made up of 80% nickel and
20% chromium, has a resistivity ranging from 1.10 × 10-6 ?m to 1.50 × 10-6
?m (0.00000110 ?m to 0.00000150 ?m) and a very high boiling point
(~1400 °C). With such a low resistivity and high boiling point, this makes
nichrome a very good conductor of electricity and ideal material for making
wires and other insulation devices.

Nichrome is commonly wound up into coils and used in heating elements
(devices that convert heat into electricity through Joule heating) such as
hair dryers, toasters and ovens. However, nichrome wires are not used as
much as copper wires (resistivity = 1.7 × 10-8 ?m) due to the high cost of
chromium.

Harvey Kwan -- 2007
----------/quote--------
--- http://hypertextbook.com/facts/2007/HarveyKwan.shtml

"boiling point?"
"wires and other insulation devices?"

Doesn't this kind of impugn the credibility of his numbers? (1 ~ 1.5
ohm-meter)

I also looked up inconel 625, which is listed as approx. 130 microhm-cm;
If I get my units right, aren't they pretty much within like 20% of each
other?

And inco 625 almost _is_ nichrome except for some non-neglible amount of
molybdenum, which probably helps with high. temp tolerance, if I'm guessing
in the right ballpark.

Thanks,
Rich