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General Liquid/Water Cooling Discussion For discussion about Full Cooling System kits, or general cooling topics. Keep specific cooling items like pumps, radiators, etc... in their specific forums.

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Unread 01-22-2002, 12:50 PM   #51
DigitalChaos
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UPDATE!!! i posted some new pics to http://www.geocities.com/xdigitalchaosx/corrosion/

or just read it here and miss out on the closeup pics :

I learned that the black coating is possibly a good thing, The coating blocks corrosion. However i think that this coating only forms on Aluminum.. so are additives worth while to put in a copper and brass system? also i would think that the coating may reduce the performance of aluminum.... now for the update: everything has gotten darker, The PurpleIce more than the Redline (with new info this would indicate that purple ice is better at stopping the corrosion)... the Distilled water STILL has no signs of corrosion. With the purpleice it seems that there is pitting where the bubbles stay...Now, i would figure that in a functioning system with moving water, that the bubbles would not have a chance to stick to the aluminum... So.. you know what that means... another test, this time with pumps.

this may also give some info to the people wanting to know if they should leave their pumps constantly on or not!

Last edited by DigitalChaos; 01-22-2002 at 02:43 PM.
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Unread 01-22-2002, 03:17 PM   #52
Brad
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the black coating may protect the Al from corrosion, but does it still transfer heat effectively? It is most likely Al2O3, or AlO, which is aluminium oxide or something like that (trying to remember from chem classes 3 years ago)

I've tried to dig up thermal conductivity values for these, but no go so far.

Another thing that may be interesting to you is that it is most likely a very very thin layer of Aluminium Oxide, which isn't likely to affect temps too much at all. I know Joe is going to ream my arse for posting this link, but it does show that a thin layer of a not-very conductive metal mightn't affect temps at all. http://www.cluboverclocker.com/revie...ckel/index.htm

here we see nickel is only 98W/m-k, while copper is around 400. The testing shows they perform exactly the same, which I think is due to the ultra thin layer of nickel.



Now, lets assume this level of Aluminium Oxide is only a couple of microns thick. Unless it has an incredibly poor thermal conductivity, like less that 30 or something, I can't see it affecting temps too much at all.

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Unread 01-22-2002, 03:29 PM   #53
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aluminum hydroxide is typically white tho not black, although it is hard to say what it becomes when the other chemicals are present.
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Unread 01-22-2002, 03:31 PM   #54
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thats Al(OH)3, not Al2O3 or AlO. Although Al(OH)3 would have gone through the entire volume of water, making it all white I would have thought (precipitate)
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Unread 01-22-2002, 03:37 PM   #55
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wow.. thanks for the info guys... most of this is really starting to fit together... but i still dont like the pits from the bubbles... one more good reason to leave the pumps ON

a good way to test the thermal properties would be:
get a setup with just distilled water.. and aluminum parts

run it for a while till it is at its peak...

then dump in the additive while its still going... and immediately record the temps for the next hour or so, this is done because the additive changes the thermal properties of water, and will give us an idea what the temps are with out the layer...

then just keep the pumps on for a day... and do peak testing again... if there is a change in temps... then we know our answer
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Unread 01-22-2002, 03:48 PM   #56
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well, thats something you will have to try, let it run with distilled water for a day, record the temps, then the next day pour in some purple ice, and see what happens, if the temps suddenly go down, then level off, or if they slowly increase as the oxidation takes place, or something...
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Unread 01-22-2002, 03:53 PM   #57
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yup.... was hoping one of you guys would do it =) i dont have any aluminum stuff... hehe
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Unread 01-22-2002, 04:06 PM   #58
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thats the problem, I don't either hehe, and I think most people don't.
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Unread 01-22-2002, 04:17 PM   #59
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yea... well maybe i will try some non aluminum testin.... (brass and copper) because this is what most have... im starting to get tired of this test after all the BS im gettin over at the [h] forum
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Unread 01-22-2002, 04:36 PM   #60
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ehh, surely you are used to their stupidity by now?
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Unread 01-22-2002, 04:43 PM   #61
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Brad even though Al2O3 (corundum) has a slightly higher thermodynamic stability, in water the typical cycle for aluminum oxide precipitation and crystallization is Al3+ (aq) -> amorphous Al(OH)3 ->crystalline Al(OH)3 (also called gibbsite). If the suspension is subjected to high temperature and pressure perhaps something else would form but that isn't a viable scenario in a jar.
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Unread 01-22-2002, 04:52 PM   #62
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hrmm.. well do you think that the slight increase in temps... and very minimal increase in pressure of a real watercooling setup would do it?
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Unread 01-22-2002, 05:37 PM   #63
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well, he said bubbles were forming, does anyone feel like putting a seal over the top of the cup to let the bubbles build up, then put a flame into it, you should have a pop.

That means it is H2
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Unread 01-22-2002, 05:39 PM   #64
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hrmm.. that would take a lot more aluminum... i would not expect more than .5-1 cc of air comming of the 1" piece of aluminum
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Unread 01-22-2002, 05:42 PM   #65
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cut the Al into heaps of little pieces so you have a lot more surface area, the reaction will be much more vigorous and much more will happen
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Unread 01-22-2002, 07:13 PM   #66
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ahhh yes... silly me...
i will have to try that on the weekend when i get a chance

also someone suggested to me to test the ph of the mixture...
the hydrogen should make it more acidic if it IS hydrogen that is being given off
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Unread 01-22-2002, 07:22 PM   #67
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yeah, that'd be an idea too, I'd have thought it'd be going alkali, cause the H2 is escaping, so there is more OH.
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Unread 01-22-2002, 07:50 PM   #68
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the oxygen would be goin to the surface of the aluminum to cause the oxidation... they hydrogen would be the by product

i was thinking that some of the hydrogen would go into the water, and some would form bubbles


man... this has turned into something requiring WAY more time than i have... i thought it was gonna be as easy as just takin pics ever so often... and just seeing what one corrodes first
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Unread 01-22-2002, 07:58 PM   #69
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H2? I thought Hydrogen was stable as a single atom which would make it H.
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Unread 01-22-2002, 08:58 PM   #70
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H2 is when it is a gas, which is the only way it exists stably. It can be just H in things like NaOH
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Unread 01-22-2002, 09:21 PM   #71
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Yes, hmm I thought Hydrogen could float around in a single attom, not pairs, guess not
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Unread 01-22-2002, 09:27 PM   #72
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chemistry sucks... tell it to leave my damn cooling system alone
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Unread 01-22-2002, 09:35 PM   #73
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Yup Hydrogen is only found as H2 when unreacted with other elements. If the solution is acidic it's because of exess H+ ions (H2 is insoluble in water and so isn't acidic or basic), the solution will become less acidic with time as H+ is taken out of solution. Also acid/metal rections always form hydroxides not oxides, so if this was acid then you would have aluminium hydroxide forming and promptly disolving, not a protective coating of aluminium oxide. Also aluminium is so reactive that this corundum coating (this is the same stuff as saphire and high quality watch glass) forms within hours of Als exposure to air. Anodizing is just creating a thick coating.

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Unread 01-22-2002, 09:37 PM   #74
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I think I learned more about chemistry in this thread than all my schooling.

hehe :shrug:
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Unread 01-22-2002, 09:38 PM   #75
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awsome... so how do you anodized copper? like... how would i find the stuff i need?

you cant anodize copper can you?
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