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The great coolant debate - Page 3

post #21 of 22
Here is a quote from another thread backing up what I've thought all along:

(http://www.overclock.net/water-cooling/915966-ek-blocks-nickel-plating-issues-failures-4.html)

"The truth about using Silver Kill Coils and distilled water only:

"kill" coils are biocide replacement, they offer no corresion resistance.

Distilled water is used as ppl think it stays non-conductive and so will limit galvanic corrosion - the problem is, once the distilled water is in the loop and in contact with all the waterblocks, tubing and radiator channels, it quickly becomes conductive again.

While most metals used in waterloops these days are very close on the galvanic scale, the very use of silver kill coils can actually be the main cause of galvanic corrosion to occur in modern waterloops.

The problem:
Modern waterloops use copper, nickel plated copper and nickel plated brass components, and the anodic index of those metals are all within the safe 0.15V (they're actually close to 0.05V) which basically stops galvanic corrosion.

The introduction of the silver kill coil in the loop is the biggest problem and IMHO the cause of the corrosion that is occurring in some ppls loops. Basically, once you add silver to the water loop, it decreases the galvanic compatibility just enough to allow galvanic corrosion to occur.

Basically, the difference between the anodic index of the silver and the other metal components in the loop are just over the safe point and is now around 0.20V-0.25V - which is just enough for galvanic corrosion to start in extreme environments (ie. inside a water loop).

So by only using distilled water, which does not stop corrosion, and then introducing the silver, you are in fact creating an environment where galvanic corrosion can occur and since the liquid in the loop is just distilled water, there is nothing to stop it."
post #22 of 22
Silver is generally safe because it is considered a Noble Metal meaning that it is inherently resistant to corrosion. Electroplating other metal surfaces with silver as actually a way inhibit galvanic corrosion. However because of its expense there is an obvious limit to doing this extensively.

EDIT: In addition, the Electronegativities of copper and silver are very close together (both aprox 1.9) which, if I am remembering my chemistry classes correctly, would inhibit galvanic corrosion between them.
    
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CPUMotherboardGraphicsRAM
i7 970 4.15 @ ~1.39v HT ON, Turbo Off EVGA x58 3x SLI 2x EVGA GTX 980 SLI (watercooled), 1x EVGA GTX ... 6 GB 1600 OCZ DDR3 Gold Edition 7-7-7-18 @1475Mhz 
Hard DriveOptical DriveOSMonitor
Samsung 840 SSD 250GB, 2xSamsungF3 1TB (Raid0) 22x Super Multi, 8x Blu-ray Reader Windows 7 Ultimate x64 2x Yamakasi Catleap Q270s (2560x1440) 
PowerCaseMouseAudio
Kingwin 1000w Platinum HAF 932 Black Interior Logitech G500 Logitech Z5500 
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