Is there galvanic corrosion in vacuum?
Is there galvanic corrosion in vacuum?
(OP)
Dear Colleagues,
I wonder if somebody could tell me if there is any galvanic corrosion between two metals (say Al and Cu)in vacuum.
As far as I know, there would have to be an electrolyte to form a complete electric circuit in order to permit the electrons flow.
Merry Christmmas!
Herivelto Bronzeado
Brazil
I wonder if somebody could tell me if there is any galvanic corrosion between two metals (say Al and Cu)in vacuum.
As far as I know, there would have to be an electrolyte to form a complete electric circuit in order to permit the electrons flow.
Merry Christmmas!
Herivelto Bronzeado
Brazil
Best Regards,
Herivelto S. Bronzeado
Brasília, Brazil
http://www.linkedin.com/profile/view?id=46319837&a...





RE: Is there galvanic corrosion in vacuum?
Nathan Brink
RE: Is there galvanic corrosion in vacuum?
Are the two dissimilar metals in contact with each other, even under vacuum? Can't prevent Galvanic Corrosion, then.
RE: Is there galvanic corrosion in vacuum?
An electrolyte is required for galvanic corrosion to allow for the ions produced as a result of the corrosion reaction to move. This is why car batteries don't work when they run low on water. Simply having two dissimilar metals in contact with each other is not enough.
Nathan Brink
RE: Is there galvanic corrosion in vacuum?
Let's think what Dhurjati Sen said that:
"... two dissimilar metals in contact with each other, even under vacuum, can't prevent Galvanic Corrosion ...."
My feeling is also that the Galvanic Corrosion will take place between the two diferent metal in vacuum (without any electrolyte) as an electric circuit may be formed inside the materials, alowing the transference of electrons between the metal.
This phenomenon seems to be similar to the Galvanic Corrosion that occurs inside the same material under diferent level of pressure.
Thank you for your thoughts!
Best Regards,
Herivelto S. Bronzeado
Brasília, Brazil
http://www.linkedin.com/profile/view?id=46319837&a...
RE: Is there galvanic corrosion in vacuum?
If an electrolyte is not necessary, but simply that two dissimilar metals are in contact, how do you suppose chrome plating protects steel?
Or a steel stud into an aluminum engine block? I've got cladding terminations in vacuum distillation towers with no such galvanic corrosion.
https://www.nace.org/Corrosion-Central/Corrosion-1...
NACE's blurb on galvanic corrosion says "in a corrosive electrolyte". I'm sure if when I get back to the office, if I open the ASM handbooks, they'll say the same thing...
Nathan Brink
RE: Is there galvanic corrosion in vacuum?
My doubt is if two dissimilar metals could criate an electric path inside them taht can cause eletrons to flow and than cause the galvanic corrosion even without any electrolyte arround.
May be this electrons flow will stop if the metals reach somehow an ion equilibrium, which may stop the corrosion in practical terms. Is it correct?
Sorry to insist in this matter. I am not a material engineer and I would like to get some experts thought on that. Thank you!
Best Regards,
Herivelto S. Bronzeado
Brasília, Brazil
http://www.linkedin.com/profile/view?id=46319837&a...
RE: Is there galvanic corrosion in vacuum?
"If an electrolyte is not necessary, but simply that two dissimilar metals are in contact, how do you suppose chrome plating protects steel?
Or a steel stud into an aluminum engine block? I've got cladding terminations in vacuum distillation towers with no such galvanic corrosion."
I really do not know about that.
However, perhaps the corrosion is so small that it will be ZERO in practical terms. My question is something "theorical".
Best Regards,
Herivelto S. Bronzeado
Brasília, Brazil
http://www.linkedin.com/profile/view?id=46319837&a...
RE: Is there galvanic corrosion in vacuum?
Dear guys, thanks for such a lively discussion.
As NBrink has said, there will not be any Galvanic Corrosion even if the dissimilar metals are in contact (electrically connected).....I agree whole-heartedly, if and only if there is PERFECT VACUUM.
Now, you get perfect vacuum only in text books. In all other vacuum scenarios, there would be some air that would serve as the electrolyte for ionic movements while the electrons move through the metals. Galvanic Corrosion would take place for sure specially if there is an area effect as well as the dissimilar metals are further apart in the Galvanic series!
RE: Is there galvanic corrosion in vacuum?
RE: Is there galvanic corrosion in vacuum?
It is not galvanic corrosion though as no metal is actually lost. It is caused by the interaction of the oxide layers (semiconductors) on the surface of the metals. This process can result in metals 'sticking' to each other after prolonged vacuum exposure. NASA has put a lot of work into this, along with what grease will survive vacuum exposure.
In theory it might be possible to form solid electrolytes on the surface of metals and drive some galvanic interaction in a perfectly dry environment. But I suspect that those surfaces would not be stable under normal conditions.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
RE: Is there galvanic corrosion in vacuum?
So, we should conclude from this discusson that the galvanic corrosion occurs ONLY if an electrolity is present.
Best Regards,
Herivelto S. Bronzeado
Brasília, Brazil
https://www.linkedin.com/in/heriveltobronzeado/
RE: Is there galvanic corrosion in vacuum?
Lots of things can either reduce galvanic corrosion to an acceptable level or even stop it entirely. The complete elimination of electrolyte is one of those things.