Mixing metals in a loop.

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Thetaint

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May 18, 2011
Can someone explain why an aluminum rad and a copper block is bad? Other than copper is just better at heat dissipation.

I keep reading that the above setup will gavlanically corrode your (Cu)water block.
 

Daemonkin

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That's exactly what it will do. Over time it will eventually eat a hole in your water block and water goes all over your mb and other components.
 

deadlysyn

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That's exactly what it will do. Over time it will eventually eat a hole in your water block and water goes all over your mb and other components.

There was a thread around here a while back where the corrosion was so bad that they were able to put a thumb tack through the hole in the block. I'm not sure how old the thread is, but I'm sure if you were determined enough, you could find it.
 

Thetaint

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I must admit, my post was kind of a setup. The only way galvanic corrosion can occur is if the two mixed metals were connected electrically (NOT just electrolytically, it HAS to be both). The fact that the two are separated by the non-conductive tubing, this eliminates any chance of galvanic corrosion.

Say if you had aluminum fittings into a Cu waterblock (providing the Al actually comes in contact with the Cu) THEN you would be in for a world of hurt.

Also, typically in the pipeline corrosion industry that I am employed in, we will protect a steel line (or steel anything) with magnesium. Overtime the magnesium anode will sacrifice itself to protect the steel. Magnesium is more electronegative than steel (to ground) (Steel-ground is around -650mV CSE, and magnesium-ground is around -1700mV CSE). The most electronegative metal out of the 2 will always be the anode (or corroding metal). So lets say that the Al and Cu were making electrical contact, Aluminum to ground is about -950mV CSE, and copper to ground can range between -100 to -200mV CSE. This situation would actually result in the aluminum corroding, and cathodically protecting the copper.

Now I ask that you PLEASE dont take this is any sort of attack, as I think the people on this forum are some of the most helpful that I have seen. Everything I said is supported in that link provided by the above poster.
 

Conumdrum

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I remember that thread. It was writtend by a lady, with clown something in her name. I forget. Was early last year. Her brother had an old Koolance aluminum topped block and a copper radiator. In the span of a bit less than a year the aluminum had corroded so bad there was holes in the block. She had a picture of a pin pushed through one of the holes. The person lost some big money. She told him, but he went ahead and did it.

With a copper block and aluminum rad, the aluminum leaches to the copper and actually builds up deposits. The rad slowly gets thin spots. The deposits on the copper don't come off with just a toothbrush either.

Back in the day they used to use anti-freeze or some other type of liquid to help prevent that. Anti freeze isn't there to cool better in cars or our PC's. It's to increase the boiling point, lower the freezing point, and add anti-corrosion like rust etc in a car setup. It was what they had back then, even though it wwasn't made for PC watercooling.

It actually cools less (holding temp etc, all that physics stuff) than good ol water. We use pretty pure water because it's cheap, cools well, and has no hard water chemicals. Like the stuff on the outside of an old faucet. You use well/tap water in a loop, you'll get ugly hard water deposits on your res sides, and in the blocks etc.

There are industrial chemicals that have better cooling properties than water. Dunno if you want them in your house. There is also pure lab water thats is pretty expensive. We don't need that purity or snake oil stuff.

Distilled/deionized with silver or a biocide is enough. Copper/nickle, brass, chrome are all close enough that we don't have the issues like in the old days.

Hope that explains it.
 

wagex

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I must admit, my post was kind of a setup. The only way galvanic corrosion can occur is if the two mixed metals were connected electrically (NOT just electrolytically, it HAS to be both). The fact that the two are separated by the non-conductive tubing, this eliminates any chance of galvanic corrosion.

Say if you had aluminum fittings into a Cu waterblock (providing the Al actually comes in contact with the Cu) THEN you would be in for a world of hurt.

Also, typically in the pipeline corrosion industry that I am employed in, we will protect a steel line (or steel anything) with magnesium. Overtime the magnesium anode will sacrifice itself to protect the steel. Magnesium is more electronegative than steel (to ground) (Steel-ground is around -650mV CSE, and magnesium-ground is around -1700mV CSE). The most electronegative metal out of the 2 will always be the anode (or corroding metal). So lets say that the Al and Cu were making electrical contact, Aluminum to ground is about -950mV CSE, and copper to ground can range between -100 to -200mV CSE. This situation would actually result in the aluminum corroding, and cathodically protecting the copper.

Now I ask that you PLEASE dont take this is any sort of attack, as I think the people on this forum are some of the most helpful that I have seen. Everything I said is supported in that link provided by the above poster.

the tubing may indeed be non conductive... but the water flowing through shure as heck aint lol and the water also picks up the cu and al molecules and deposits them on the next and bam there they are touching :)
just get nickel plated block and be good :)
 

Thetaint

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Yep....stainless top on a copper block. Stainless sacrificed itself to protect the Cu base. That deposit on the Cu is actually a good thing in the corrosion world, and is a byproduct of cathodic protection. However, not so good in a block. And the res.? Stainless with probably brass fittings. In theory, fittings should only go into acrylic/acetal, as they will electrically isolate the fittings from the block.
 

Thetaint

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the tubing may indeed be non conductive... but the water flowing through shure as heck aint lol and the water also picks up the cu and al molecules and deposits them on the next and bam there they are touching :)
just get nickel plated block and be good :)

You are about the nickel plating. And you are also right about the water. For any electrochemical corrosion cell to work (and therefore corrode) it requires a few things, if any of them are removed, no corrosion. You need the anode (more electronegative metal), the cathode (more electropositive metal), an electrolyte (water, high conductance=bad), and a metallic path (any sort of metal, including themselves, to complete the path).
 

Thetaint

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Seems like the guy in that thread had some additive issue as well. Poor design on the manufacturers part.

There is another type of corrosion that can occur from moving liquids across metal. But that generally is only an issue with high pressure systems, and when the liquid is filled with crap. Natural gas and oil usually bring up some nasty water. We have a division that inserts metal discs into pipelines, then pulls them and compares the weight before and after, over a period of time.
 

deadlysyn

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I decided to become determined to find the thread that came to mind. It was all the way back on page 31 in this sub forum (if that gives you an idea of my determination). The member that posted it was CrazyV, it was a Koolance block (copper base, aluminum top), and Primochill ICE for the coolant.

Here is the thread.
http://www.overclockers.com/forums/showthread.php?t=636600

I also passed by a few of my old threads, and as much as I hate to say it, a year and a half ago, I think I seemed as newb as they get.:p
 

Thetaint

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I decided to become determined to find the thread that came to mind. It was all the way back on page 31 in this sub forum (if that gives you an idea of my determination). The member that posted it was CrazyV, it was a Koolance block (copper base, aluminum top), and Primochill ICE for the coolant.

Here is the thread.
http://www.overclockers.com/forums/showthread.php?t=636600

I also passed by a few of my old threads, and as much as I hate to say it, a year and a half ago, I think I seemed as newb as they get.:p


Yeah that makes sense. The copper and aluminum were touching, so galvanic corrosion could occur.

Watercooling products have come so far over the years. Its funny when you look at the LAST page of the pictures thread, and then the FIRST page. First page seems so ghetto.
 

Higdon

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Honestly, Thetaint, this whole thread just sounds like you stroking your ego and showing the rest of us how much more you know about this stuff than the people that have been doing it for years. I am not saying this is your intention, this is how it comes across. We have very smart people here who work in more industrial fields than I can think of. I would think that someone would want to be careful before we start a pissing contest.
 

Thetaint

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May 18, 2011
There is absolutely no pissing contest intended. Just saying that mixed metal components electrically isolated will not corrode each other galvanically. I just thought i would explain it, as opposed to being an internet troll and going "NO U WRONG LOLOL".
 

rge

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The fact that the two are separated by the non-conductive tubing, this eliminates any chance of galvanic corrosion.

Um, no.

Corrosion occurs as copper ions soluble in water deposit on the aluminum forming the galvanic cell. One method that corrosion inhibitors work, is by preventing ions from becoming soluble or by scavenging ions.

Most galvanic corrosion occurs from metals separated by water exactly as an aluminum block and copper rad are in your example. It would be uncommon to see a manufacturer stupid enough to actually screw some aluminum into copper with water present, which is why that way isnt to common.

Why do you think we have corrosion inhibitors? Do you think corrosion inhibitors were designed or would work if people attached aluminum to copper? the answer is no. Corrosion inhibitors exist to prevent soluble ions from attaching to non-similar metals, ie to protect the exact type of corrosion that occurs when mixing an aluminum rad with copper block or vice versa.

Many years ago, when more common to mix metals, there were frequent pics of corrosion from running an aluminum radiator with a copper block or brass rad with aluminum block.

Edit: or another example is mixed metals with car radiators and engine blocks. Corrosion inhibitors break down and loose effectiveness over years, which is why your supposed to have rad flushed every 5-7 years or so. Maybe next time I will just tell the mechanic, no sir just fill up rad with distilled water, my engine and rad are separated by hoses.
 
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Thetaint

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Um, no.

Corrosion occurs as copper ions soluble in water deposit on the aluminum forming the galvanic cell. One method that corrosion inhibitors work, is by preventing ions from becoming soluble or by scavenging ions.

Most galvanic corrosion occurs from metals separated by water exactly as an aluminum block and copper rad are in your example. It would be uncommon to see a manufacturer stupid enough to actually screw some aluminum into copper with water present, which is why that way isnt to common.

Why do you think we have corrosion inhibitors? Do you think corrosion inhibitors were designed or would work if people attached aluminum to copper? the answer is no. Corrosion inhibitors exist to prevent soluble ions from attaching to non-similar metals, ie to protect the exact type of corrosion that occurs when mixing an aluminum rad with copper block or vice versa.

Many years ago, when more common to mix metals, there were frequent pics of corrosion from running an aluminum radiator with a copper block or brass rad with aluminum block.

Edit: or another example is car aluminum core radiators with iron engine blocks. Corrosion inhibitors break down and loose effectiveness over years, which is why your supposed to have rad flushed every 5-7 years or so. Maybe next time I will just tell the mechanic, no sir just fill up rad with distilled water, my engine and aluminum rad are separated by hoses.

No, of course having inhibitor doesn't stop if the two metals are coupled. It wouldnt do a damn thing to stop it lol.

The only reason that you would have galvanic corrosion in an Al rad and Cu block, is due to the flow. If electrolyte was stagnant, it wouldnt be an issue. But, we should keep that pump on just in case :D

And my statement about no electrical contact stopping galvanic corrosion is 100% true. If copper from the block makes its way to the Aluminum rad, then TOUCHES the rad, well I guess that is an electrical contact.

Hell, even just one metal in an electrolyte will galvanically corrode with itself. Which inhibitor can assist with.

One more thing, I really don't want to turn this into a pissing match, nor do/will I argue. Lets be civil people.
 

RollingThunder

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No, of course having inhibitor doesn't stop if the two metals are coupled. It wouldnt do a damn thing to stop it lol.

The only reason that you would have galvanic corrosion in an Al rad and Cu block, is due to the flow. If electrolyte was stagnant, it wouldnt be an issue. But, we should keep that pump on just in case :D

And my statement about no electrical contact stopping galvanic corrosion is 100% true. If copper from the block makes its way to the Aluminum rad, then TOUCHES the rad, well I guess that is an electrical contact.

Hell, even just one metal in an electrolyte will galvanically corrode with itself. Which inhibitor can assist with.

One more thing, I really don't want to turn this into a pissing match, nor do/will I argue. Lets be civil people.

Mixing metals in a loop.

Originally Posted by Thetaint

Can someone explain why an aluminum rad and a copper block is bad? Other than copper is just better at heat dissipation.

I keep reading that the above setup will gavlanically corrode your (Cu)water block.

Thetaint,

What seems provocative here is that you already knew the answer to the question you posted. It projects the appearance of baiting responders that may not be as informed on the subject as you are into a debate.

Your technical explanation would have been more useful if it was posted as a technical resource in the "Cooling Forum," don't you agree?

RT
 
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rge

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No, of course having inhibitor doesn't stop if the two metals are coupled. It wouldnt do a damn thing to stop it lol.

The only reason that you would have galvanic corrosion in an Al rad and Cu block, is due to the flow. If electrolyte was stagnant, it wouldnt be an issue. But, we should keep that pump on just in case :D

And my statement about no electrical contact stopping galvanic corrosion is 100% true. If copper from the block makes its way to the Aluminum rad, then TOUCHES the rad, well I guess that is an electrical contact.

Hell, even just one metal in an electrolyte will galvanically corrode with itself. Which inhibitor can assist with.

One more thing, I really don't want to turn this into a pissing match, nor do/will I argue. Lets be civil people.

After rereading the thread, perhaps you just did not understand that copper solubility would 100% of the time cause deposits on aluminum creating the galvanic cell, otherwise you would not have stated..."The fact that the two are separated by the non-conductive tubing, this eliminates any chance of galvanic corrosion".

So did not mean to come across as pissing match, just trying to prevent someone new into water cooling from reading this thread and thinking it is ok to use an alum rad with copper block, without corrosion inhibitors, then end up with an expensive mess.