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In Reply to: Some more data. posted by Jon Risch on January 06, 2002 at 10:28:09:
OFHC is typically specified as being 99.97% pure or better, with a minimum of 99.95% purity, and with less than 0.02% Oxygen,I'm not aware of any of the OFHC standards which allow for 0.02% oxygen. That level of oxygen would still cause embrittlement of the copper when heated in reducing atmospheres, which is precisely what OFHC was developed to prevent. It's processed in an oxygen-free atmosphere so there's no oxygen to get into it in the first place.
while ETP may only be 99.9% pure, with as much as 0.08% oxygen. Some grades of ETP are slightly better, say 99.95% pure, but the oxygen content is still not limited to the smaller values that OFHC is limited to.
ETP is intentionally and very precisely oxygenated (and I'm not aware of any standards which allow for more than 0.04%). It could just as well be processed in the same oxygen-free atmosphere as OFHC. The oxygen is intentionally added to scavenge impurities which would otherwise be left in suspension, and when left in suspension, reduces conductivity. OFHC can't take advantage of oxygen scavenging so it needs to be of a higher inherent purity in order to maintain the same level of conductivity as ETP, all else being equal.
While the nominal conductivity of the two may be nearly identical, the amount of crystalline disruption due to impurities is probably a lot less for the OFHC copper.
I don't see that this would be the case, all else being equal, given that the impurities of OFHC are left in suspension and effectively become part of the crystal as opposed to singular inclusions within the crystal as occurs with oxygen scavenging.
se
Follow Ups:
If you have some more definite numbers (I was told these by a cable engineer), then I would be interested it them.Minimums and typical are different based on what I was told.
I have seen OFHC as being as high as 99.99% purity, and seen other numbers for ETP as well, but what is typically available is what one should be looing at.
As for the crystal disruption of 0.X percent oxygen vs. 0.0X percent of some other impurity, in either case, there will be a disruption in the regular crystal lattice of the copper. I would have to think that
if there were one tenth (or less) as many crystalline dissruptions in the nature of impurites, that there would be less over all crystalline disruption period.
Jon Risch
If you have some more definite numbers (I was told these by a cable engineer), then I would be interested it them.
Minimums and typical are different based on what I was told.The CDA's got some problems on their web site (getting a "Could not connect to JRun Server" message) so I can't pull up the standards specs right now. They're covered under the following:
UNS 10100 (OFHC certified)
UNS 10200 (OFHC)
UNS 11000 (ETP)They're available from the following page so you can try later if they get their "JRun Server" problem solved:
Standard & Properties for Copper and Copper Alloys
I have seen OFHC as being as high as 99.99% purity, and seen other numbers for ETP as well, but what is typically available is what one should be looing at.
OFHC certified is minimum 99.99%. OFHC is minimum 99.95%. ETP is minimum 99.9% with 0.04% oxygen.
As for the crystal disruption of 0.X percent oxygen vs. 0.0X percent of some other impurity, in either case, there will be a disruption in the regular crystal lattice of the copper. I would have to think that
if there were one tenth (or less) as many crystalline dissruptions in the nature of impurites, that there would be less over all crystalline disruption period.When the impurities are left in suspension, they're distributed throught the crystals. When they're scavenged by the oxygen and taken out of suspension, then the crystals simply form around them.
Think of it this way: Take a tube and insert a cylinder of open cell foam the same size as the inside of the tube. Measure the restriction of airflow due to the open cell foam. Then melt the foam so it just forms a single solid pellet. Place that in the tube amd measure the restriction of airflow again.
The restriction of airflow will be considerably less with the latter even though the foam has the same mass and occupies the same amount of space as it did before. That's because when it's a foam, and its mass is spread out over a much wider area, it significantly reduces the mean free path of the air molecules.
The same goes for impurities in copper. When the impurities are left in suspension, like the foam, they also reduce the mean free path of the conduction electrons. When the impurities are scavenged and congealed into more tightly packed clusters, the mean free path of the conduction electrons is greater and the relative conductivity increases.
se
http://properties.copper.org/standard-designations/wrought-coppers.htm
Jon Risch
Still can't get through via the CDA's main page. What route did you take to get there?se
Your link took me here (I have been here before, but they do have new stuff :-) ):
http://properties.copper.org/Since the "Standard Designations for Copper and Copper Alloys – Wrought and Cast." link was giving an error, I tried the "European Standard Compositions for Copper and Copper Alloys." link:
http://properties.copper.org/euro-standards/homepage.htm
Which lead me to:
http://properties.copper.org/euro-standards/astm.htmland: (table 18) is
http://properties.copper.org/standard-designations/wrought-coppers.htm
Just a little side trip around the error.
Jon Risch
Your link took me here (I have been here before, but they do have new stuff :-) ):
http://properties.copper.org/
Since the "Standard Designations for Copper and Copper Alloys – Wrought and Cast." link was giving an error, I tried the "European Standard Compositions for Copper and Copper Alloys." link:http://properties.copper.org/euro-standards/homepage.htm
Which lead me to:
http://properties.copper.org/euro-standards/astm.htmland: (table 18) is
http://properties.copper.org/standard-designations/wrought-coppers.htm
Just a little side trip around the error.
Pull over. I think I'm gonna be car sick. :)
Oh well, by hook or by crook.
Anyway, getting back to the subject at hand, this puts the numbers issue to rest. For basic OFHC (UNS10200/C10200) the maximum oxygen content allowed is 0.001%. For the electronics grade UNS10100/C10100, the maximum is a mere 0.0005%.
For ETP (UNS11000/C11000), the footnote reads "Oxygen and trace elements may vary depending on the process." I've just never seen it specified at greater than 0.04%.
Thanks for the trail blazing, M'bweebwee. You can put that machete away now. :)
se
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