Grounding Mixed Metal Loops

[Nanook]

Hypothetically, couldn't you just hook up a simple cable with a good connection from your rad to a strong grounding point and eliminate all galvanic corrosion?

[Tristerin]

Or just use #science and a corrosion inhibitor.  I only run copper/alu loops.  I have pictures of radiators and blocks (aluminum) cut open after 6 months of 24/7 load showing...gasp...zero corrosion

 

Anyhow - wouldn't that electrical current need to be in the water, which would then transfer to the radiator (or vica versa) directly into the PSU/ case metals?  Im not sure on your end but I just use literal car antifreeze 

[For Science!]

4 minutes ago, Nanook said:

Hypothetically, couldn't you just hook up a simple cable with a good connection from your rad to a strong grounding point and eliminate all galvanic corrosion?

No (that's not how it works, but I wouldn't be able to explain it, so you're going to have to read up on it yourself), but you can put in sacrificial metals that corrode first (instead of the Aluminium) this was used in TT radiators that had a sacrifical zinc coating. It was shite though.

 

 

[Nanook]

9 minutes ago, For Science! said:

No (that's not how it works, but I wouldn't be able to explain it, so you're going to have to read up on it yourself), but you can put in sacrificial metals that corrode first (instead of the Aluminium) this was used in TT radiators that had a sacrifical zinc coating. It was shite though.

 

 

My reasoning was that in a mixed metal loop with flowing fluid you basically creating a galvanic cell (a battery). If you give that battery an opportunity to discharge itself to an exterior grounding source (grounding terminal on a wall outlet), then the loop should maintain charge equilibrium and thus no corrosion.

 

So is that wrong?

[For Science!]

Just now, Nanook said:

My reasoning was that in a mixed metal loop with flowing fluid you basically creating a galvanic cell (a battery). If you give that battery an opportunity to discharge itself to so exterior grounding source, then the loop should maintain charge equilibrium and thus no corrosion.

 

So is that wrong?

Well, it is the act of current passing from one metal to another that causes it, so the more noble metal stays as is as the less noble metal gets eaten away. If the case of copper and aluminium, copper is more noble and so the ions flow in that direction and the aluminium gets eaten away. If you had a common ground (i.e. something even more noble than copper) now you have both metals corroding instead of just the aluminium. If you have another metal that is less noble than the other two, (i.e. zinc) then you have a sacrifical metal, but as described above, it is not a good idea.

[RollinLower]

29 minutes ago, Tristerin said:

Or just use #science and a corrosion inhibitor.  I only run copper/alu loops.  I have pictures of radiators and blocks (aluminum) cut open after 6 months of 24/7 load showing...gasp...zero corrosion

didn't know those also worked for galvanic corrosion. the more you know i guess?

 

[Tristerin]

1 minute ago, RollinLower said:

didn't know those also worked for galvanic corrosion. the more you know i guess?

 

Vehicles have been doing this since the inception of anti-freeze - they are just large, HOT, conductive, mixed metal loops.  I personally use Prestone 50/50 pre mix with their patented Cor-Guard.  Its a documented chemical and more documented then top brand loop juice in terms of what is in it and %'s.

[Nanook]

22 minutes ago, For Science! said:

Well, it is the act of current passing from one metal to another that causes it, so the more noble metal stays as is as the less noble metal gets eaten away. If the case of copper and aluminium, copper is more noble and so the ions flow in that direction and the aluminium gets eaten away. If you had a common ground (i.e. something even more noble than copper) now you have both metals corroding instead of just the aluminium. If you have another metal that is less noble than the other two, (i.e. zinc) then you have a sacrifical metal, but as described above, it is not a good idea.

I am aware that current passing from one metal to the next in a galvanic cell causes corrosion. For example, in a copper (cathode) and zinc (anode) battery electrons flow from the Zn to Cu due to a potential difference. Cu atoms are reduced and plate out from a CuSO4 solution onto the cathode, while at the same time Zn atoms are being oxidized and entering solution. This causes the "dissolving" or "corrosion" of the Zn anode. This same process occurs in a loop, so if you shorted the ground with a physical wire from the bare metal of a rad or CPU bloc, then electron passage could be shorted along the wire to say a wall outlet ground terminal. This would cause electrostatic equilibrium and stop potential differences of the metals and thus end corrosion.

 

It works kinda like an antistatic bracelet you are supposed to wear when building. It discharges and equilibrates you with ground, so just running a wire from your loop to some strong external ground should perform the same function.

[GhostRoadieBL]

On ships it's large sacrificial zinc blocks which corrode more readily than other metals, there's also a system using a platinum anode to saturate the water with negative ions. Cathotic protection is super expensive and not worth the couple dollars for swapping fluid every few months or adding a zinc rod for a small loop. 

[For Science!]

6 minutes ago, Nanook said:

I am aware that current passing from one metal to the next in a galvanic cell causes corrosion. For example, in a copper (cathode) and zinc (anode) battery electrons flow from the Zn to Cu due to a potential difference. Cu atoms are reduced and plate out from a CuSO4 solution onto the cathode, while at the same time Zn atoms are being oxidized and entering solution. This causes the "dissolving" or "corrosion" of the Zn anode. This same process occurs in a loop, so if you shorted the ground with a physical wire from the bare metal of a rad or CPU bloc, then electron passage could be shorted along the wire to say a wall outlet ground terminal. This would cause electrostatic equilibrium and stop potential differences of the metals and thus end corrosion.

Basically, no, even with a wire on the external, you still have a path of electron flow between the copper and aluminiujm in the loop, so it will still pass current. You seem to be very convinced that it will work, and I would recommend you to try it out yourself, and also at the same time also question why galvanic corrosion is not a solved problem for other industries if this idea actually had any grounding to it.

[Nanook]

2 minutes ago, For Science! said:

Basically, no, even with a wire on the external, you still have a path of electron flow between the copper and aluminiujm in the loop, so it will still pass current. You seem to be very convinced that it will work, and I would recommend you to try it out yourself, and also at the same time also question why galvanic corrosion is not a solved problem for other industries if this idea actually had any grounding to it.

In theory the electrochemistry of it should work, but theory and real world.....well um yeah. At the least I bet it would slow down corrosion some.

[Mick Naughty]

Well the rads are already attached to the chassis, and so is the psu. So when you plug it into the wall and ground the entire system, isn’t that the same goal? Or are you trying to add a 1/0 cable to a pc and connect it to a ground spike? 

[Lipe123]

The wire just makes everything worse by allowing even more current to pass between the metals.

 

Use a chemical corrosion blocker.

[Nanook]

13 minutes ago, Lipe123 said:

The wire just makes everything worse by allowing even more current to pass between the metals.

 

Use a chemical corrosion blocker.

I don't think a simple grounding cable would make anything worse, but it probably wouldn't solve the issue completely. It would be a form of cathodic protection, but cathodic protection is not 100%. Still a chemical corrosion blocker plus a wire providing a more direct path to ground or even to an exterior sacrificial metal such as zinc would help.

[Lipe123]

2 minutes ago, Nanook said:

I don't think a simple grounding cable would make anything worse, but it probably wouldn't solve the issue completely. It would be a form of cathodic protection, but cathodic protection is not 100%. Still a chemical corrosion blocker plus a more direct path to ground or even an exterior sacrificial metal such as zinc would help.

Literally using the word "ground" means current flow to ground. And you are connecting all the components together , the path to the other components will then have WAY less resistance than a ground connection.

Ground is literally a stake in the soil outside your house, it's not exactly and amazing conductor.. so you will promote current flow between the components. 

 

When there is current there is corrosion.

[Nanook]

13 minutes ago, Lipe123 said:

Literally using the word "ground" means current flow to ground. And you are connecting all the components together , the path to the other components will then have WAY less resistance than a ground connection.

Ground is literally a stake in the soil outside your house, it's not exactly and amazing conductor.. so you will promote current flow between the components. 

 

When there is current there is corrosion.

Of course current flows to ground. The idea is that providing a better ground would alleviate some of the current flowing between metals in a mixed Al/Cu loop. It would provide an exterior path for electrons in the loop and it would be harmless. If Cu blocks are ripping away electron from an Al rad, then providing a direct contact grounding wire or sacrificial metal would allow the Cu to rip electrons away from that instead of the Al rad. This the Al gets to keep its electrons and shouldn't corrode, erm as much as without cathodic protection  least. Running a wire from the loop to an exterior sacrificial metal such as a small bar of Zn would provide that cathodic protection.

 

Some form of cathodic protection for a loop would be something cool to test. If it works out good, then it is pretty convenient and cheap to replace an external chunk of Zn.

[Lipe123]

2 minutes ago, Nanook said:

Of course current flows to ground. The idea is that providing a better ground would alleviate some of the current flowing between metals in a mixed Al/Cu loop. It would provide a path an exterior path for current out of the loop that would be harmless. Running a wire from the loop to an exterior sacrificial metal such as a small bar of Zn would probably be even better.

 

Some form of cathodic protection for a loop would be something cool to test. If it works out good, then it is pretty convenient and cheap to replace an external chunk of Zn.

No current flows toward the direction of least resistance. You basically have a galvanic battery with a + and - side and now you are putting a wire between them and then also connecting that wire to ground. The shortest route for current would be directly between the components not to ground in this case.

 

Cathodic protection is stupid, that dissolving metal is going to cause buildup of small particles and its a short term fix.

 

Bro you are trying to make this work too hard. If it was a thing everyone would be doing it.

[Nanook]

6 minutes ago, Lipe123 said:

No current flows toward the direction of least resistance. You basically have a galvanic battery with a + and - side and now you are putting a wire between them and then also connecting that wire to ground. The shortest route for current would be directly between the components not to ground in this case.

 

Cathodic protection is stupid, that dissolving metal is going to cause buildup of small particles and its a short term fix.

 

Bro you are trying to make this work too hard. If it was a thing everyone would be doing it.

There would not be a wire connecting the Cu block and Al rad. Maybe just a platinum probe inserted into the loop somewhere and then connected to a wire would would be connected to a chuck of Zn in solution in a container outside the entire rig.