Interesting

[Donny M]

I set up another electrolysis tank to derust Rose's front rims. The only material I had for an anode was some aluminum plate and some 6 1/8" copper tube. I also didn't have any washing soda or TSP on hand so I borrowed some Cascade dishwasher detergent. Boy did this thing cook Drawing 40 amps on the 200 amp (start setting) on the charger was no problem. I let it cook for 16 hours drawing 20 amps, here's the nice little surprise after the cooking was finished:



Other side:


I'll bet I won't have to worry about flash rust

I'm sure that getting to correct salts and using the optimum current would make this more efficient.
Off to paint

[Scott]

sweet

[Rudi]

Donny:

Does this mean you are going to write a neat How To Electroplate Your Cub Front Rims More

[George Willer]

Donny,

I'm guessing you had the positive connected to the rim and the negative to the copper?

[Jim Becker]

No he had to have the positive on the copper. Metal disappears from the positive electrode providing the positive ions in the liquid.

[beaconlight]

Does copper hold paint well?
Bill

[Donny M]

No he had to have the positive on the copper. Metal disappears from the positive electrode providing the positive ions in the liquid.

Jim,
Exactly, as you would with a steel anode.

Bill,
I was wondering that myself. I think with the small amount of copper on the rims they should hold paint ok, time will tell

Rudi,

This is no more than a standard electrolysis tank with two differences, 1st is the anode which is copper and 2nd I have a high amount of Cascade concentration.
To plate the rims efficiently, one would need copper sulfate and sulfuric acid, something which I'm not willing to get into at this point.

[Buzzard Wing]

That is pretty cool Donny!!

Guess your rims weren't as beat up as mine (they are many years younger and not from northern VT). Mine took a pretty long time in the big tank, at least 3 days each.

I figure copper is too expensive these days.

Larry

[Arizona Mike]

Ronny, how do they look inside

[Donny M]

Spike,

They look the same inside except for the Star Of David, the imprint still has white paint in it

[George Willer]

Donny,

I'm guessing you had the positive connected to the rim and the negative to the copper?

Where did I go wrong? An electron carries an arbitrary negative charge so I would think the negative terminal (cathode) has a surplus from which the electrons flow through the electrolyte to the positive (anode) which has too few... taking material along with the flow. This flow in our cleaning tanks removes material from the part we are cleaning and deposits it as crud on the anodes.

That's why I assumed Donny's system plated the copper from being reversed. Thinking I may have mis-remembered what I learned nearly 60 years ago I looked it up.

http://www.finishing.com/faqs/howworks.html

[Jim Becker]

Did your electrolite start to get a green color? If Cascade has any phosphates in it (not unlikely), your solution probably now has some copper phosphate in it. Copper phosphate is used some as a fungicide. I don't think it is known to be particularly hazardous. Likewise, the aluminum probably would result in some aluminum phosphate. Aluminum phosphate is used in baking as a leavening agent. So presumably it is safe enough.

[Boss Hog]

Donny
Did it have that black layer on it and did I understand you used both copper and aluminum and how did they hold up
David

[Donny M]

Jim,

The Cascade has no more than a 6% phosphate content, according to the label. The soultion is somewhat green but Cascade also has blue/green chips, who knows what that stuff is The Cascade is working great removing rust but it's not as efficient as it could be if I really wanted to plate the rims.

David,
Yes there is black muck in the solution. It's boiling away pretty hard (25 amps) so it doesn't have time to develop a film on the surface. The copper anode also builds a black muck layer, I read someplace that this is exaggerated by high current during the process.
The copper tube I'm using is 6 1/8" dia with a .075" wall and is holding up just fine. I didn't try the aluminum.

One thing I have noticed using the copper; the current doesn't drop off as it does when using steel. If anything it's increasing, I guess the more it's used the more copper phosphate is added to the soultion.

[Jim Becker]

George,
Your reference page has a pretty good explanation. I bet if you go back and review it, it will become clear to you. What Donny did is essentially the same as "A second demonstration" on that page.

I hope I get this right, or at least close enough to get some warped version of the general idea. I'm not a chemist.

When a piece of iron rusts, the process is oxidation. Iron looses it's electrons, becoming a positive ion and combines with a negative oxygen ion. Fe + O2 --> Fe2O3. Fe2O3 is ferric oxide, common red rust.

To copper plate something a copper anode is stuck in a solution and given a positive charge. The positive charge is looking for electrons, which is sucks out of some of the copper. This leaves some positive copper ions on the surface of the copper anode. These ions dive into the solution, where they are attracted by the other electrode that has a negative charge (the cathode). As soon as they run into the negative electrode, they snatch enough electrons to become neutral (this is reduction) and grab onto the surface of the electrode. At this point, they become part of the copper plating on the electrode. This is going to work a lot better on the clean (non-rusted) parts of the cathode, which I think you can see in Donny's rim pictures.

Meanwhile, we still have a surplus of electrons hanging around on the rim, trying to go cause other reduction reactions. One of the things it works on is the rust on the electrode (the reason we are messing with this thing in the first plae). One possible reduction action is to undo the oxidation that caused the rust in the first place. So SOME of the rust will be separated back into iron, with the oxygen bubbling off into the air. So yes, some of the rust is actually turned back into iron that is put back in the rust pits that it came from. Some of the rest of the rust is reduced back into a different iron oxide. Ferrous ferric oxide (Fe3O4) is a common black rust. I believe that is what most of the black residue is on the parts we have cleaned. When it forms, it doesn't hold as tightly on the part as the red rust does. Consequently, a mixture of it, red rust and iron comes loose and a lot of it falls to the bottom of the container. Another posible iron oxide is ferrous oxide (FeO). It is also black. I hope we aren't producing much of that because it is potentially explosive.

The anode needs a continuous supply of electrons to send back to the battery charger so the battery charger can send them back to the cathode. It got some from those copper ions that jumped off the anode to swim towards the wheel rim. But that only supplies enough electrons to give back to the copper when it reaches the rim. So more need to come from somewhere. The only source left is the negatively charged phosphate ions swimming in the solution. Since they are negatively charged, they are attracted to the anode. They give up their extra electrons on contact. And I presume they take up residence on the anode as the glop we need to clean off every so often.

So the bottom line is that positive ions move towards the cathode while negative ions move towards the anode. The positive ions, being metals, form nice crystaline structures that become plating while the negative ions are things like phosphates that turn to glop.