Copper Oxidization?

[Serra]

I was at my in-laws house earlier today looking at a Zalman CNPS7700Cu (http://www.ncix.com/products/index.php?sku=13700&vpn=CNPS7700-CU&manufacture=ZALMAN%20TECH) (the best pre-heatpipe-era cooler invented) that was in a computer I had pieced together for them a long time ago when I realized that although it was made of solid copper with (as far as I was aware) no special treatment, it wasn't showing any signs of oxidization (discoloring/turning green). To me this seemed strange, as I don't think copper products are given anodized platings and it's definitely not painted, so... why isn't it noticeably oxidized? It's likely over 3 years old and has been in contact with a computer that's on probably 18 hours/day.

I tried researching an answer, but all I can get is that as far as any old review sites knew at the time, it was solid copper and none make any mention of a coating. Metallurgical sites etc all seem to be of the consensus that anodizing isn't something you see on solid copper and suggest a paint/varnish or just cleaning copper every so often... so, I guess I'm hitting a dead end.

Any thoughts?

[STEvil]

chemically coated

[Serra]

Makes sense. I'm just going to go out on a limb and ask whether anyone knows whether it has any notable impact to thermal performance. I'm going to assume it's a very thin layer and doesn't provide much impact, but if anyone can verify that would be good to know.

[DeltZ]

low humidity of indoor conditions means that oxidation doesn't really occur?

[[XC] Hicks121]

low humidity of indoor conditions means that oxidation doesn't really occur?

Thats along the lines I was thinking too, much higher than ambients in the case when on keep the humidity down.

[[XC] Lead Head]

Just like how your wrenches and steel computer cases don't rust in side, but leave em outside in the rain for a day, and look what happens.

Anyways, it takes A LONG time for copper to turn green, and even then it has to be in real harsh weather. I believe first copper will turn a brownish color, then eventually start turning the green we are familiar with.

The 18 year old copper plumbing in my house has no corrosion on it yet, even the pipes that constantly sweat in the summer

[[XC] gomeler]

It's chemically coated. The moment your hand touches uncoated copper it will begin to oxidize. I see this all the time when I build a cascade, starts to turn brown.

[Serra]

Hmmm, now there seems to be some new arguments on both the treated & untreated sides of the fence.

I suppose it all relates to speed of noticeable / effecting oxidization. Some say it happens almost instantly, some say it takes forever to happen in an indoor environment. So... which is it? That was one of the things I searched while thinking about this issue initially and couldn't find any information aside from "it begins to odixize quickly"... but "quickly" isn't much of a qualifier.

If it just goes a slightly duller brown, does that affect temperature conduction? I'd be inclined to think that a slight dulling wouldn't have a measurable impact, but I have no proof to back that up (I do know that a thicker layer conducts at about 1/20th the rate of regular copper though).

[Zaskar]

Lead Head;3007661']Just like how your wrenches and steel computer cases don't rust in side, but leave em outside in the rain for a day, and look what happens.

Anyways, it takes A LONG time for copper to turn green, and even then it has to be in real harsh weather. I believe first copper will turn a brownish color, then eventually start turning the green we are familiar with.

The 18 year old copper plumbing in my house has no corrosion on it yet, even the pipes that constantly sweat in the summer

Thats correct.
Isnt the green actually some crystal/mineral that starts to grow/build up after time?

[Serra]

Thats correct.
Isnt the green actually some crystal/mineral that starts to grow/build up after time?

Nope, the green is actually the final stage of copper oxidization.

[[XC] Lead Head]

Actually, I remember seeing something on the history channel that it can take upto 20 years or so for super exposed copper, like copper roofs to finally turn all green.

[STEvil]

Depends on the conditions.

I have heatsinks which begin oxidizing within weeks and others which are still almost new looking. Some are chemically coated, others are not. Lapping removes it from any of them.

Also it is important to note that there are different stages of oxidization. Copper turning green takes a long time.

[bhavv]

I surely hope that none of my copper oxidises:

http://i118.photobucket.com/albums/o102/bhavvv/DSC00056.jpg

O.o ... Theres a lot of copper for one PC.

[fart_plume]

part of the reason the heatsinks aren't oxidizing as fast is they are hotter than the surrounding air, thus the humidity is being burned off before it can condense on the copper. I have a thin sheet of copper I bought 6 or so years ago from McCarr-Master and it has still yet to show any signs of oxidation. If I left it outside it would start to oxidize in a matter of weeks. So so everyone will know even stainless steel will oxidize overtime. The only metal I know of that doesn't oxidize is gold.

[aspire.comptech]

To get rid of copper oxidation you can squirt some ketchup on the affected area and let it sit for about 20-30min then rinse it off and it'll be shiny like new.

Nifty little trick us water coolers often use for the bases of blocks.