Aluminium in a Waterloop - A no no??

AFK_Matrix

AFK_Matrix

AFK_Matrix

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Hi,

Ok was looking at a Aluminium reservoir and got told on another forum to avoid any aluminium in a water loop. But could someone please explain why not to have aluminium in a loop? The aluminium I was looking at was anodized and they still said this was a no go. How comes?

Thanks
 
It isn't aluminium specifically afaik. The thing is to avoid mixed metals if you can - e.g. a copper block and an aluminium res, or whatever. Having mixed metals allows them to corrode in the system.

Most people on this forum don't may much attention to this though, as it is surprisingly difficult to actually get a system that has only one metal in it. If you're using additives that stop corrosion and/or de-ionised water, you should be fine.
 
The reason why its a no no is all to do with reactivity of the metals.
the aluminium 'sacrafices' its self.
beacsue theryes 2 mixxed metals, aboth speread far apart int he reactivity series, ti forms a crude battery ( thats right ...; like what you put in ** TV remote ! ) becasue fo this the aluminium will erode and reacty quickly casueing all sorts of problems includign cosmetic problems, weakening, blocking, etc etc
if it is unavoidable it is recomended to ad and extra 10-15 % of anti freazer to your loop than the normal 5%. this will help prevent such reactions but still best if you can just avoid aluminium !
 
Your mixing straight away as pump parts arnt copper and nor are the brass barbs or the rads anyway
 
gcsechem389xa.gif


that will give you some idea !
as you can see the metals near the top react Very quickly, you know how fast aluminum will develop an oxide layer just in air.

If you have a gold ring, or silver jewelry you will notice how it just never tarnishes, or goes dull. (if left in storage for a long time )
 
Basically, the more reactive Aluminium is happy to shed it electrons into the water, and the less reactive copper is equally happy to eat them up.

It's not that simple either, the electrons 'dissolve' (more on this later) to form Ionised water (ah-ha I hear you cry... this is why we use 'de-ionised' water) this Ionised water then flows round the loop and woop! meets the copper, the copper reacts, bonding to this happy extra electron like an old chum, and floating off... bingo! you've lost some of your copper waterblock (corrosion)...

Meanwhile, at the Aluminium block, electrons are still being pulled off by oxidising the Aluminium to alumium oxide (oxygen comes from the water) and releasing Hydrogen (which will form as bubbles on the surface of the block)... Hence you get a not-very-thermally-conductive layer on that Block/res made from AlO (ALuminium Oxide) and Hydrogen bubbles.

AND if that isn't enough, all these flowing electrons means that there's an electrical current flowing through your loop... it won't affect much, but it'll build up over time and what if it adds that extra deadly 0.01V to the wrong leg on one of your volt reg's and suddenly you've got a Vcore of 12...
(it'll run.... all over the motherboard)

THAT's why you avoid mixing metals, and why Aluminium isn't a very good metal for water loops, unless you have anti-corrosion additives.

And to think i dropped Chemistry...

Hope that clears things up...

Mike
 
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welshtom said:
Pumps are plastic, rads are copper and brass is made out of copper!
Click to expand...

The pumps are mainly plastic but they have a magnetic coil around the shaft which causes the prop to turn. Just looking at the spare one i have for the eheim pumps and it doesnt look like copper - more plasticy but it cant be if its magnetic.

Didnt realise rads were copper - they didnt feel heavy enough to be

Brass is a compound of zinc and copper and zinc is slightly higher than aluminium in the reactivity series + DD high flow barbs are aluminium arnt they?
 
Most barbs are, unless of course they are of the plastic/nylon type.

According to all this then the Zalman reserator is a very good example of how not to do it. If i remember rightly the reserator itself is aluminium and the blocks are copper.

You can cut down the galvanic corrosion by using a quality additive which prevents corrosion in the first place. After all, take a car engine for example. That is a total mix of different metals and they don't have much of a problem with corrosion in the waterways. If they did the engine would end up seizing due to overheating.
 
pastymuncher said:
Accorrding to all this then the Zalman reserator is a very good example of how not to do it. If i remember rightly the reserator itself is aluminium and the blocks are copper.
Click to expand...

Not quite, Isn't the inside of the res painted in the same finish as the outside? hence the water wouldn't come into contact with the actual aluminium.

besides, The coolant you get with the reserator almost certianly has an anti-corrosion additive.
 
Aaah, all this brings me back 3.5 years to A-level chemistry.

I'll add a useless bit of information now as the good stuff is already gone.

Audi use/(used?) Aluminium in their cars and was the main reason why they didn't rust (obviously they can't rust as rust is Iron oxide but hey, I'm making it simple) or should I say corrode. The aluminium oxide layer which is built up protects the car from corrosion very well as it is a stable compound. So, lt's put this more simply:

Audi use Aluminium for the cars
Air (oxygen) reacts with it forming Alu Oxide
The car doesn't corrode easily
Car looks good for a long time,
The End. It's a smidsy adventure :D.
 
Mikebert4 said:
Not quite, Isn't the inside of the res painted in the same finish as the outside? hence the water wouldn't come into contact with the actual aluminium.

besides, The coolant you get with the reserator almost certianly has an anti-corrosion additive.
Click to expand...
Most if not all aluminium WC parts are anodised which puts a hard surface coating on the aluminium. This works well till it gets scratched and the soft alu is exposed.
 
DaveMac said:
Most if not all aluminium WC parts are anodised which puts a hard surface coating on the aluminium. This works well till it gets scratched and the soft alu is exposed.
Click to expand...


ahhh... you learn somthing every day :D


I suppose that anodising would be effective, but i've always stuck like glue to copper in my WC systems. saves all this effort and debate.
 
Thanks for all the replys I get what you mean now :). Now this all has to do with the reservoir I want in my loop. Basically its an Aquatube which is aluminium but anodized. So surely like the Zalman it would be protected?? There is going to be an acrylic version soon but its gonna cost more, so was just wondering if the Aluminium version would be ok. From all your replys I guess I am going to have to go for the Acrylic one.

Thanks
 
I've been having a google :)

If it's Anodised it'll be fine, I guess the real danger comes with cheap blocks/Rad's that arn't anodised or copper...

I'd still go for an acrylic res or somthing, but thats because I like my PC to look goood (yes, yes, i do have UV water and UV cathodes! leave me alone!)

but essentially, If it's aluminium, make sure it's anodised, and if it is:

A: Don't scratch it
B: Use some anti-corrosion additive just in case...
 
The most vulnerable point on any anodised block, res etc. is threads for the barbs, especially if metal barbs are used.

As long as you use the correct addative ratio to prevent/reduce galvanic corrosion the alu version is fine, though I would wait for the acrylic version to remove the potential and reduce the amount of addative required.
 
I use all copper and I still have about 15% corrosion inhibitor in the form of Zerex Racing Coolant - I like to play it safe.
 
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