Battery effect w/Swiftech MCW462 block?

[krp]

If one uses mixed metals in a liquid cooling system, (i.e. copper waterblock with an aluminum radiator for example), one risks galvanic corrosion because the coolant acts as an electrolyte with the dissimilar metals acting as poles of a battery.

Does this still happen if the two unlike metals are in direct electrical contact with each other?

For example: The Swiftech MCW462-xx waterblocks have a copper base with an anodized aluminum top, do the Swiftech waterblocks experience galvanic corrosion as a result, or does the fact that the two halves are in direct electrical contact prevent this somehow? Or does the metal to metal contact give the "circuit" a return path and make the corrosion worse??

[hielko]

Does this still happen if the two unlike metals are in direct electrical contact with each other?

I'm not really sure, but I think the answer is yes. Galvanic corrosion is a redox reaction and those don't care about direct or indirect contact. As long there's contact a reaction will take place...

[krp]

I kinda suspected that direct contact wouldn't help much.

I recall many years ago having several problems with a water-intake line for my parents home, (on a lake), which had a brass check-valve on the intake that kept falling off every couple years because the galvanized iron pipe would rot away with the most severe corrosion closest to the brass fitting on the end, tapering almost like a sharpened pencil in the last couple feet!

I suspect the blue anodizing Swiftech just started using is to try ans slow down corrosion problems...probably the top (which probably attacks the top aluminum half the worst.)

In any case, I think I will go with Dangerden's all copper block. Thanks!

[GuyBFF]

Swiftech was talking about upgrading customer units to anodized due to the problem which they recognize. As for as I know not many problems with anodized blocks as long as you run water wetter or anti-freeze (in moderation).
I'd still stick with Danger Den Maze 2 (love mount and die cooling, I just installed one), or BE Jagged Edge (if you need a second choice).
Get a copper rad, All BE Cooling, Danger Den Cube or one of those heater core styles.
Swiftech makes best air cooled, but who knows why aluminum / copper mix and 1/4" swivel fittings (no fan on the aluminum, maybe just riding coat tails of MC462 Design and copied looks?) I think compares to the Senfu units. Also is know to leak at swivel joints.

[hielko]

You can also put a metal in your reseviour to prevent redox reactions with the copper or aluminium. the metal you will need to use should be 'lesser' than aluminium. Zink (dutch name, I hope the english name is similair) should do the trick.

[GuyBFF]

It's "zinc", but the dutch spelling gets the point across anyways .
All you need is a very small piece (half a AAA battery) and should last very long, I'm just always cautious about introducing other particles to the coolant (I don't know if dissolved zinc particles would say chew up the pump seals, I've heard of UV additive doing this - the non dye types)