electrolytic plasma polishing?

[coppercone2]

Has anyone here been around this process?

It is like electropolishing but you use high voltages (300V or so) to polish objects. Looks like a rather expensive power supply is needed for this task, but the results are excellent and for a regular polish user it might be a small price to pay in exchange for your lungs.

But this process looks to be pretty high up on the 'potentially deadly' list.

Anyone have any experience? Not really too approachable but it might be interesting to talk about.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6471503/

[Alex-lab]

This process is highly energy consuming. It needs about 1A/cm2 at corresponding voltage about 100V, which depends on the specimen material etc.
The main feature of this treatment is operation within negative differential resistance (NDR) region on the current-voltage curve. To get into NDR you should overcome current peak, therefore you may need even more power for the process initiation.
As far as I know, the mechanism has not yet been well understood.

[coppercone2]

I tried it with a 250V supply @ 200 ma. I setup a little stainless dish of citric acid and put a wire in a grabber hook fluke safety thing in a vise. I lowered the wire into the solution until the meter read like 200V (a few mm). The wire looks clean but not as nice as initial (its like 14 gauge solid wire).

While I guess its a fail, it does a wonderful job of deburring. I got something close to a dome shape after the wire was cut with electricans side cutters.


I think maybe if you just try to do it that way, its too close to the surface and air gets in there. I think you would need a tiny part that is on a tiny wire that is in the middle of the bath to do this properly, you can't skim the surface, but it might be useful if you need a smooth wire end with no work

Also tried it with a nail that was in OK condition (wood nail). The very tip that was submerged got shiny, it looks nice. But like a very small bit.

I read it takes 200V. I notice the PSU makes a different noise right around 200V, it sounds... fizzy. Not sure if its because I was closer to surface or if its the plasma forming.

I am guessing for it to be easy/practical to setup a experiment,you need more juice.


I don't like the idea of working on it without a interlock box. Its too easy to forget something and touch the work piece.


BTW if you can think of a experiment that you think would work with a 250V 250mA supply, let me know.I think a larger electrolyte tank might help, and suspending the object on a teflon solid wire so it does not expose more surface, since I have so little to work with. And ammonium sulfate.

************

also, where did you get the density from? I read 0.2A/cm2. You say 1A/cm2

if my number is correct, then for ~250mA, I should be able to do 1.25 square centimeters.

this means a 6.3mm sphere should be polishable I think

For practical objects, I imagine the only thing you can do for electronics is a small washer, or a tiny screw (more like watch maker), assuming you got fixturing of some kind that can do it...