Re: stainless conductivities

[brian whatcott <inet@INTELLISYS.NET>]

At 18:19 6/11/99 -0500, Tim Sullivan wrote:
...
> > The typical "resistance wire" we use in wire-wound resistors and in
> > heaters is nichrome wire. ... Nichrome is an alloy with
> > the approximate composition of 60% Ni, 25% Fe, and 15% Cr.
> > ...
> > Michael D. Edmiston...

> ...
> If we are saying that SS has an anomalously low conductivity, then we need to
> say what the standard is. A deviation from the [Wiedemann-Franz] relation
might
> be taken as evidence of anomalous transport. Here is some data taken from the
> CRC:
>  .../abbreviated/

> Substance:              thermal         electrical      product
>                        conductivity    resistivity
>
>                        (J/s-cm-K)      (microohm-cm)   [[uW.ohm/K]]

> Titanium                0.17            80              14
...
> SS 304                  0.17            72              12
...
> Copper                  3.89            1.7             6.6
...
> Solder 50-50            0.30            15              4.5
...
> So stainless does seem to be on the extremes both of resistivity and the
> [Wiedemann-Franz] ratio, though it isn't exactly alone. Interesting that it
> shares the extreme with (commercial) titanium, since one usually thinks of
> alloys as having the higher resistance.
>
> Tim Sullivan
> sullivan@kenyon.edu


I enjoyed this exchange.
Spooked by talk of the complexity of the phonon/electron
mechanisms for conductivity, I took a look at a sample of recent
science reportage of work in this general area,
from IOP London.   Here's the URL:

 http://www.ioppublishing.com/PEL/article/cm08003l1/full/

I concluded it was a product not totally out of reach
of the well-disposed.

brian whatcott <inet@intellisys.net>
Altus OK