# Effect of impurities on Thermal Co-efficient

Hello,
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?
Thanks,
Mark
Normally the thermal coefficients of metal conductivity is conform by their electrical conductivity. 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.
Regards Nick.
"Mark" ???????/???????? ? ???????? ?????????: news: snipped-for-privacy@g47g2000cwa.googlegroups.com...
Hello Nick,
I am not sure that I understand.
Do you mean that the heat coefficient is proportional to the resistivity?
Btw My education is in physics and I do not know engineering terms.
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.
Mark
jbuch wrote:
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.
A. Bulsari
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 more competitive.
Regards,
Mark
(Touloukian)
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 temperature.
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.
Jim
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 value.
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.
A. Bulsari

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