I have an aluminum cap I was using to cap my t-line until I could find a nylon or brass one but I never found one locally. Well when I removed the system recently I noticed the cap had quite a bit of corrosion on the inside and outside. Water in the system never touched the cap but it still corroded all over. I tried taking a picture but it just wont come out well.

That corrosion in the cap is a good thing. It's sacrificial - so the copper/brass corrodes less (e.g. stays shinier) than without the aluminum anode. This is a selling point. We do the same for vehicles and steel structures, why not waterblocks. Give it a copper wire tail to hang in the coolant.

Aluminum does pit when it corrodes. So chunks can fall off.

Still, I think people might buy these as expendable anti-corrosion anode plugs. Replace every 6 months...

Or, you could just use 10% glycol, and avoid the problem all together? :shrug: Why mix metals when you dont HAVE to?

try google
you are wrong

jfetting, thank you.

i've been doing some tests with aluminum and brass and copper in water together.. and i haven't been able to get the aluminum to corrode badly enough that chunks start falling off it.

that's gotta take YEARS

But if its caused by condenstion, the condensation will be pure water and the glycol will have no effect.

geek and SMan
the 2 of you are congratulating each other on how equally ignorant you both are about the same subject

BTW SMan - why Aluminium anyway, can't you just machine some brass caps instead and solve the whole issue?

put them in a closed system with a reasonable flow rate, and watch galvanic corrosion take place.

look through dansdata to see this is action with a aluminum WB, and copper radiator.

i can't be bothered to explain simple chemistry.

all fine and good until said chunks clog your loop

not just water evaporates, guys....think puddle of gasoline/mineral spirits/acetone/alcohol.

cathar said nickel plating is possible for 25 cents each....and is there a problem with machining out of brass?

if you wanted a sacrificial metal, just stick zinc in your system. and i don't think comparing the use of sacrifical metals, in oxygen rich environments applies to water cooling. where the whole point of sacrifical metals, is that they are more reactive to oxygen, and therefore stop the steel from rusting.

Aluminum is a poor sacrifical metal, because its expensive, and also a aluminium oxide layer protects the rest of the aluminium form oxidisation. thatis until a bit falls off, in the case of a water cooling system.

guys, if the aluminum is anodized, nothing is going to react, corrode, fall off, blah blah f-in BLAH..

why the hell can't any of you understand that?

i've been advised to never nickel plate aluminum, and i have been shown what nickel plated aluminum can look like when finished. very interesting and nothing you want to do with.

and bill, who the hell are you talking too? who is "geek" and who's congratulating who?

Geek is Jfettig. Nickel plating AL certainly is not uncommon. Example: http://www.enetshoponline.com/niplcoramsif.html

or

http://www.bakerprecision.com/aqp5c.htm

or

http://www.pfonline.com/articles/pfd0318.html

Corsair and Silver Prop Used Nickel plated AL on ther water blocks aswell

Not saying you should do it thought. Type 2 anodozing would be fine IMO. Should be able to get all 50 done at the same time for not much $$$. Unless you wanted different colors... Looks like great machine work.

If you did nickel plate them, and a customer asked about corrosion, then you could say any copper in the system must decay until it falls off before the cap loses its shine. Nickel, paired with copper, eats.

You are right anodising will pretty well stop reaction with copper. And how often do we see any computer components older than a decade anyway?

As I said before, any doubts about adding aluminum to a copper system you may answer with the good news that your aluminum plug actually helps protect any copper it electrically connects with.

So you can guarantee a perfect anodize on every part?

every piece will be completely anodized. (once they are anodized, each piece will be seperated.

if YOU scratch that anodization(takes a pretty deep scratch, not something light), than that is no longer my problem, as it was you who messed it up.

look at dtek, they anodized their aluminum topped waterblocks.. do you see problems? no.

I don't own a dtek waterblock - I prefer not to mix metals in my water loop. What others do is their perogative.

SMan
I was addressing the 2 most ignorant posters in this thread
ignorance is curable, but it may take some effort
it seems clear you do not think, just gather opinions you feel are in support of your point
I am hoping geek will get an education

this topic has been talked to death on OCers, and here
search some: galvanic corrosion, cell corrosion, etc.
examples abound, there was a D-Tek al top on OCers, some really nifty nickle plated al on OCAU - look around

aluminum is a acceptable material, with appropriate precautions:
1) anodize it
2) ALWAYS use a corrosion inhibitor
and if you follow #2, you can skip #1; UNLESS you have a moist air environment (where the corrosion inhibitor cannot protect the surface - as a previous poster did make clear)

sound like your application ?

go learn something

I think you have a few options. in order of preferance

1. Make them out of brass
2. Nickle plate them
3. Type 2 anodize them

Personaly i feel that all 3 of those options offer acceptible protection but it is clear that others have higher standards than i do. If you make things to sell to the public you need to cater for them. Arguing the toss does not sell the caps! The way you will sell the most caps is by producing brass caps. This is the same reason that i have started making copper/brass waterblocks insted of copper/alu. Not because of my needs/oppinions but because i want them to sell and therfore you must choose the option that is most desirable to whoever is buying.

FYI i run an aluminium res with an aluminium cap. The res and cap are not anodised or plated in any way. When i take the cap off there is allways a few drops of condensed coolent on its underside. So far after 6months it has not corroded. Thats why i do not worry too much but it does not mean it cant happen.

ok, thanks.

the caps are anodized now, and corrosion should not be a problem.

I do know what I am doing, my family has been in the machining industry for several decades, and I've felt that unanodized aluminum is pretty safe in a watercooling loop, as I've never in my life have seen badly corroded aluminum. I may see spots of corrosion after several months/years, but those are preventative and removable by just using a 3m scotch brite pad to 'scrape' it off.

And in the years of experience, I've been suggested against nickel plating aluminum, as anodization is the only real way to go for aluminum.

dunno why they weren't made out of brass to begin with

does your res touch the case, out of curiosity?

if t-line touches case, and case touches copper rad, corrosion _will_ result

They were made out of aluminum because aluminum was on hand, I guess. Maybe it was free. Stang_Man then sells them cheap. We all win.

"Corrosion _will_ result" - well really vague tarnishing is about all the "corrosion" we're likely to see on sealed anodised. Of all places corrosion could occur, I'll take visibly through clear tubing on an easily washable part. We should hope the anode corrodes, because any galvanic corrosion on the anode plug is proof of corrosion protection in less accessible copper components. Why "protect" this component from performing a useful service?

My hot water tank has an anode plug, too. It's marked so. Perhaps I should take it out and send it to a plating service?

welcome Kobuchi, to those who post w/o knowledge

only magneisum, 99.9%, will function as an anode in a cu/al system

no. stick your anode where you will not forget it - your source of info

Harsh but ohh so funny/true.

I got a question, would Zinc be a good anode in these systems? (pleading ignorance here, but in the back of my head there is a nugget of info that says it is a good anode in galvanic corrosion environments. )

zincs work for a boat, but not for WCing
had one in my chiller with a ss bath and an aluminum Little Giant pump, the zinc did nothing

in terms of galvanic potentials pure magneisum is the only way,
but still far better to preclude corrosion of any sort due to the corrosion product