Electrolytic rust removal

[3v0]

Does anyone have any knowledge about using PWM in this process?

The long version
Electrolytic rust removal is a form of reverse electroplating. Rust is pulled from the part to be cleaned and deposited on sacrificial anodes. When the rust is gone the process stops. It generally takes at least 24 hours to derust a part.

If one pushes too much current (power) through the electrolyte it heats up and the parts absorb hydrogen and become brittle. I am wondering what would happen if one used PWM to keep the average power level the same but at an increased voltage. This has been studied for electro plating but I have not seen mention of it for this process.

The basic process is described numerous times on the web.

 

[alec_t]

If it is only the heating, and not the instantaneous current or voltage, which causes H absorption then IMO PWM should be ok provided the workpiece has significant thermal inertia.

 

[shortbus=]

While not rust electrolysis related, have you ever heard of or tried using molasses for rust removal? Not the grocery store stuff but the kind from a animal/farm feed store. It doesn't work as fast as electrolysis but still does work pretty fast (days to weeks, depending on amount of rust)

Is Zombie Engines your blog? Had a look there and will go back and read more.

 

[3v0]

Alec I will do a bit more research and see if I can confirm that.

Shortbus
I have heard of using molasses. But I recall reading the feed store stuff did not work as well as the people food variety. I did think about it but it is even more of a mess and you have to keep buying new molasses.

ZombieEngines is my blog. It is just a chronicle of me playing with small engines others have discarded.

If you like fun mechanical stuff you may also like my other blog Essick VR30RE Vibratory Roller which covers my efforts to bring a small road roller back to life. I had it working for about 15 minutes and the front drum suspension failed.

 

[3v0]

I have recently learned that the process is a lot cleaner if carbon rods or blocks are used in place on the steel anodes. Does anyone know of a source of carbon blocks or rods at least 10 inches long?

 

[Mike_2545]

quick search of Ebay found this **broken link removed**

 

[Mickster]

Interesting blogs 3v0, I have added the links to my favourites for further reading.

 

[Joe G]

check a welding supply house for the carbon rods. Usually about a foot long from .125" and up.

 

[3v0]

If the guy on ebay was selling 8 or 16 for that price I would jump on it. But he only has the 4.

Trying to do this on the cheap which I should have mentioned up front. Maybe looking for the impossible.

 

[KeepItSimpleStupid]

Look under graphite: https://www.ebay.com/itm/Graphite-S...462?pt=LH_DefaultDomain_0&hash=item4ac5cf2f16

There is graphite and carbon graphite and I don;t know what the difference is: **broken link removed**

 

[atferrari]

And those used for arc projectors (Lincoln). Not even sure if in use today...