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M0CNL > TECH 27.05.06 10:23l 80 Lines 3932 Bytes #999 (0) @ WW
BID : D10501M0CNL
Read: GUEST DL1LCA
Subj: Re: Resistivities of metals
Path: DB0FHN<DB0MRW<DB0SON<DB0SIF<DB0FHK<DB0MKA<DB0LJ<DB0RES<DK0WUE<SP7MGD<
7M3TJZ<ZL2BAU<GB7ESX<GB7COS
Sent: 060527/0519Z @:GB7COS.#31.GBR.EU #:32217 [Essex, Point Clear] FBB7.00i
From: M0CNL@GB7COS.#31.GBR.EU
To : TECH@WW
VK2ZRG WROTE:
> Hello Dick and readers,
>
> I've compiled a list of metal resistivities/conductivities from various
> sources. CHEMIX is a programme that gives lots of data on all the elements.
> It came from the web. CHEMIX gives conductivities, the first column of
numbers.> I've taken a reciprocal for the second column and the third column is
relative
> resistance to copper (1.678). The 4th, 5th and 6th columns come from books.
> Radiotron Hbook is "Radiotron Designers Handbook" and Ref data ITT pub is
> "Reference Data for Radio Engineers" 4Th Ed. The 7th column is from the list
> from Paul M0CNL, posted on packet the other day. The last column is data that
> I gleaned fron the Encyclopedia Britannica.
> Paul's number of 18 for chromium could be out by a factor of 10. Clearly his
> numbers for brass and tin are out be a few orders of magnitude. So I'm still
> not sure what the right answer for chromium is. I've yet to find out exactly
> what happens to the properties of chromium at 37C.
>
> ------- Relative to copper -------- Resistivities
> ....From CHEMIX programme..... ARRL Radiotron Ref data M0CNL Encylp
> M Conduct. Resistivity Hbook HBook ITT pub list Britan
> Ag 0.630 1.587 0.946 0.94 0.950 0.950 1.590 1.590
> Al 0.377 2.653 1.581 1.60 1.640 1.640 2.650 2.655
> Au 0.452 2.212 1.319 1.40 1.416 1.416 2.440 2.440
> Co 0.172 5.814 3.465 5.600 5.600
> Cr 0.077 12.920 7.700 1.80 18.00 13.00
> Cu 0.596 1.678 1.000 1.00 1.000 1.000 1.673 1.682
> Fe 0.093 10.753 6.409 5.68 5.600 5.600 9.660
> Ni 0.143 6.993 4.168 5.10 5.050 5.050 0.000 10.51
> Pb 0.048 20.833 12.417 12.80 12.78 12.78 22.00 20.65
> Pt 0.096 10.417 6.208 6.160 6.160 11.00
> Rh 0.211 4.739 2.825
> Sn 0.091 10.989 6.549 6.70 6.700 6.700 1150 11.36
> Ti 0.023 43.478 25.913 48.70
> V 0.048 20.833 12.417 26.00
> Zn 0.166 6.024 3.590 3.40 3.400 3.400 6.00
>
> Brass 3.7-4.9 3.90 3.90 700
>
> Resistivities are in micro ohm-cm
>
> 73s from Ralph VK2ZRG@VK2WI.#SYD.NSW.AUS.OC
As I explained in my SP to you those figures were not "mine" as such, they
were taken from a website that when you asked me, I couldn't remember the
address of and that they were only from some research that I had quickly done
at the time. I have since gone back through my history logs and found that
they came from:
http://www.answers.com/topic/table-of-resistivities
and have since noted that they do have some kind of disclaimer at the top of
the list which I only seem to be able to see part of, but looking at the page
source rather than the webpage reveals:
THE CONTENT OF THIS TABLE IS UNCERTAIN, ESPECIALLY THE COEFFICIENTS OF
RESISTANCE. RESISTIVITIES SEEM TO BE ESSENTIALLY CORRECT, BUT THEIR VALUES ARE
APPROXIMATE (EVEN WHEN HAVING MANY SIGNIFICANT DIGITS) - THE RESISTIVITIES ARE
ALL ON THE CORRECT ORDER (multiplied by the correct power of 10).
Which kind of says that there may be errors but they believe them to be
"ESSENTIALLY CORRECT" and that "THE RESISTIVITIES ARE ALL ON THE CORRECT
ORDER" so I posted them believing them to be so.
I am sure that your post is not intentionally trying to make me look stupid,
but from the way I read it, it does. This is not intended as the start of a
flame war or anything like it, just that I think that people should be
presented with all the information and let them make up their own minds.
All the best
Paul
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