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Oxygen in Copper

Could someone give me a very brief 'review' of the role of oxygen in copper & various grades.

As someone who constructs a lot of apparatus, sometimes involving 77K or

4.2K, sometimes at >300K, sometimes high currents, I often use copper. Its electrical & thermal conductivity are often important.

There are loads of different grades, & sometimes you cannot get the shape/size you want in the premium OFHC oxy-free-high-conductivity material, which is also expensive & horribly soft especially if its been heated.

You also see PDO (phosphorous deoxydised), often tube, poor conductivity esp. at low temperature ETP electrolytic tough pitch FRHC fire refined high conductivity other unqualified 'high conductivity' HC grades.

Could someone summarise the role of oxygen in copper (obviously crucial) & something about these other grades with regard to thermal & electrivcal conductivity? Or point me to a coherent comparison? Its sometimes hard to find data, especially at low (or elevated) temperatures, and its very hard to get an overall 'picture' of the situation. Yes, I have don Google searches; hard to form a clear overall view! I'm a half electronic engineer half physicist; Im not a metallurgist.

Harvey

Reply to
Harvey Rutt
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The influence of oxygen on condutivity is low since it is present as precipitates. Simply speaking: 1% copper-oxide in pure copper will reduce the conductivity by 1%.

Michael Dahms

Reply to
Michael Dahms

copper.

heated.

conductivity

crucial) &

electrivcal

Harvey:

A brief summary article on the electrical conductivity of copper and its alloys can be found in the Articles on the Key to Metals site at

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New Year to the group!

Pittsburgh Pete

Reply to
metalengr

Still one of the best sources of thermophysical property data is the CINDAS compilation..... which attempts to cover the range of data from

0K to the melting point of the material.

YOu can find it in libraries. It is large and expensive.

The database in original paper format was 13 volumes with nearly 1000 pages in each volume.

It was my first data source whenever I needed cryogenic data on materials. There have been several other compilations of specific cryogenic data, most of which are out of print.

There was an excellent book on cryogenics and cryogenic material properties by Reed and Clark published in the 1980's. It seems to be out of print as well, but librarians can find you a copy.

Most of these books explain the need for purity and order of the copper crystalline structure for high thermal conductivity at cryogenic temperatures.

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Thermophysical Properties of Matter Database The Thermophysical Properties of Matter Database (TPMD), contains thermophysical properties of over 5,000 materials with approximately

50,000 data curves. This is the searchable, electronic version of the Thermophysical Properties of Matter, the TPRC data series. It is available in CD-ROM or Web-based formats. The database is continually updated and expanded.

Advances in Cryogenic Engineering Materials (Advances in Cryogenic Engineering, Vol 34) by A. F. Clark, R.P. Reed (Hardcover)

Reply to
jbuch

Thank you - that is a good start to better understanding! So presumably all the effects on thermal & electrical conductivity are due to the presence or absence of the other things such as phosphorous in PDO copper.

But it also leads to the question *why* OFHC & PDO? Why are people so keen on removing the oxygen if it doesnt affect conductivity? Must be some other (mechanical properties?) effect those precipitates have?

Further info on PDO/ETP/FRHC etc would still be very welcome.

This bit of the jigsaw, whilst very welcome, almost increases my mystification!

Harvey

Reply to
Harvey Rutt

Very useful thanks! If anyone has anything similar for thermal condiuctivity, especially at low temperature, that woulod be magic!

Harvey

Reply to
Harvey Rutt

In nearly-pure metals, electrical and thermal conductivity run more or less parallel (Wiedemann-Franz law).

HTH

Michael Dahms

Reply to
Michael Dahms

To many oxides embrittle copper.

Even a low a mount of oxides react with diffusing hydrogen during heat treatment in hydrogen-containing atmospheres. The resulting high-pressure water-bublles severely embrittle copper. Hence non-oxygen-free copper-grades are not suitable to brazing and welding.

Michael Dahms

Reply to
Michael Dahms

This is the nub of the problem. Its easy to get data on pure metals. But they are pretty useless engineering materials often, & hard to come by! The nearest thing is OFHC, but availability is somewhat limited (stock sizes etc) & cost high.

Getting data on ETC, FRHC, PDO seems rather harder, especially away from room temp.

Harvey

Reply to
Harvey Rutt

I cant believe all the wrong answers that people give here.. do any of these people work in the industry??? Oxygen is added to copper to increase the electrical conductivity. Spec call for 150 - 400 ppm not a whole lot..

Adding oxygen oxidizes impurities and takes them out of solid solution (where they would morally reduce electrical conductivity). IN the old days....early to mid 1900's Oxygen free copper had lower conductivity than standard oxygen bearing copper and probably still does in many instances.. Refining techniques produce copper with lower impurity level Oxygen free copper came to being, not because of higher conductivity, but because some applications, cannot tolerate oxygen in the copper, i.e. hydrogen brazing will cause oxygen bearing copper to embitter by forming H20 in the copper matrix. Many people are using OF copper that don't really need it and they pay a nice premium for it

Tom Chandler

Reply to
TC

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