Can anyone tell me how to find out the effect of impurities in copper
wire on thermal co-efficient of conductivity?
More specifically, does a small amount of iron in copper wire
significantly increase it's resistance at high temperatures as compared
to pure copper?
Normally the thermal coefficients of metal conductivity is conform by their
So you can mesure and calculate the coefficient of electric resistance
depending on impurities, and be sure that the thermal conductivity
coefficient will be the same conformity.
"Mark" ???????/???????? ? ???????? ?????????:
I believe he is making reference to the Wiedemann-Franz Law ..... well
known in Thermal Physics.
If the electron is the (dominant or only) vehicle by which both the
thermal energy and electrical charge are conducted, then there must be a
relationship between the thermal and electrical conductivity.
Sometimes, phonons conduct enough thermal energy to break the
proportioning between thermal and electrical conductivities.
You can "Google" the rest now.
Thank you for the interesting article.
However it does not seem to answer my question.
I would like to know how the thermal coefficient of resistance depends
on the quality of copper wire. I do not see how thermal conductivity
is related. It may be my ignorance since I only have a batchelors
degree in physics.
The best of the copper producers do not seem to know how impurities
affect thermal and electrical conductivity, except for a few simple
heuristics. Even some of those producing/processing copper
particularly for thermal and electrical conduction purposes do not
find it worthwhile/economical to find out.
I have heard from their customers (companies using copper wire) that
the copper wire suppliers have shown no interest in development work
of this kind, the first step of which would be to find out the
quantitative effects of impurities or alloying elements on
conductivity and other properties. Thermal coefficient of electrical
resistance is much farther away.
Thank you for your response. Now I feel better about failing to find
the answers I was looking for.
It is curious that it has not been studied more since when one
considers the huge role that copper plays in our society. On the other
hand I would not expect businesses to spend to much time on it since
they can not afford to spend money on research if it does not make them
Actually there is a literature of sorts on "Thermophysical Properties of
Matter" ,by Touloukin and it is available in a few large good libraries.
It is dated from the 1970's, nine volumes of nearly 1000 pages each
volume and hundreds of figures with thousands of citations to original work.
Frankly, few people really are able to need access to data at cryogenic
or elevated temperatures... as most engineering is done around room
Like in clothes..... if you aren't "average" like, you will pay extra
for what you need, because most people aren't interested in your super
large size clothes.... or your need for data not at room temperature.
It is such a mess to have data on thousands of materials, and then to
have to have data for hundreds of temperatures for each of those
thousands of materials.
However, if you know how to ask for data, an afternoon on the telephone
talking with copper producers and distributors will surely get you to
someone who can pretty much answer your questions.
If you don't know how to ask for data, hell may freeze over before you
get the data you want.
It is a bit more pathetic than that. First of all, if this were
supposed to be pure research, one would expect universities to study
this, but today even most publicly funded universities won't do
anything other than customer service irrespective of its academic
If businesses - copper producers and processors would work on this,
they would increase their competitiveness (by offering better
combinations of properties, possibly at a lower cost) but any such
investment these days should have a guaranteed and a short pay back
period. Even though the clients of copper wire suppliers are
interested, the suppliers are not interested in these issues. (See the
Internet sites and you will find most of them claiming to invest
heavily in R&D, environmental protection, and show a lot of concern
for the welfare of their employees.)
The situation for most other materials is not too different.