Electrolysis of Alloy metals

[Ignus99]

Its been a very, very long time since the last time I was balancing chemical equations so I figured someone with it much more fresh in their minds would be able to help me. My situation is this, I am attempting to use two seperate alloys in direct contact with eachother and passing a high current through them, and was wondering if there would be any adverse side effects to it being in the rain and such (electorlysis build up on one side, and decomp of the other.... dont want that).

the two alloys are Copper-Magnesium, and Copper-Cadmium.

600V DC current will be running through it with a maximum amperage of 4000A, and will be directly exposed to the elements indefinitly.

THANKS in advance for your help!

New to the forums,
KVD.

[freeztar]

I regret that I can't help you, but I'm curious as to the function of such a system.

[Ignus99]

its for a light rail transit alternative contact wire, we are thinking about switching to copper magnesium from the current copper cadmium for the electrical properties without being carcinogenic like cadmium. unfortunetly its been years since ive didnt any kind of electrolysis.

[Ignus99]

nobody?!?!?! hehe, i didnt think it would be an issue, tricks on me eh? anyone with any help would be appreciated.

[Mercedes Benzene]

You really shouldn't have any problems other than normal wear and tear. Electrolysis is defined as the seperation of compounds using an electric current.
Since you're not dealing with any chemical compounds, then you don't have to worry about anything.

[Ignus99]

Originally Posted by Mercedes Benzene

You really shouldn't have any problems other than normal wear and tear. Electrolysis is defined as the seperation of compounds using an electric current.
Since you're not dealing with any chemical compounds, then you don't have to worry about anything.

this is a good point, but i've also heard somewhere that rust on a car is a form of electrolysis, when a drop of salt water falls on it, it creates a current and steals electrons from the iron. and cars are made of alloys as well... who knows, i may be talking out of my rear, but is there anything out there that can comfort me and my argument about rusty cars and a similar possibility on my application?

[freeztar]

Originally Posted by Ignus99

this is a good point, but i've also heard somewhere that rust on a car is a form of electrolysis, when a drop of salt water falls on it, it creates a current and steals electrons from the iron. and cars are made of alloys as well... who knows, i may be talking out of my rear, but is there anything out there that can comfort me and my argument about rusty cars and a similar possibility on my application?

From a basic standpoint (I'm not a chemist), it seems that water and O2 are going to be the potential culprits. Salt (NaCl) increases the conductivity of water. More salt equals more oxidation potential. You shouldn't have problems with salt on a rail, but of course there's current to deal with. It looks like you'll have to do a bit of chemistry work. Here's a good explanation of rust that I found: Road Salt Ate My Car!


You might find this interesting:
http://www.mse.eng.ohio-state.edu/~f...a/yoonbuch.pdf

[Mercedes Benzene]

this is a good point, but i've also heard somewhere that rust on a car is a form of electrolysis, when a drop of salt water falls on it, it creates a current and steals electrons from the iron. and cars are made of alloys as well... who knows, i may be talking out of my rear, but is there anything out there that can comfort me and my argument about rusty cars and a similar possibility on my application?

Rust on a car is a form of spontaneous oxidation. The electrons move as a result of a chemical change. The movement of electrons in a redox reaction is entirely different (and opposite) from running a current through a substance. Now, if there is a significant amount of ions in the rain water when the current is passed from the electrodes, some decay may be present, but in your application, it's doubtful that anything significant would occur. You're not using iron, and it seems that your alloys would be fairly unreactive.

That's my two cents.

[Turtle]

Originally Posted by Mercedes

Electrolysis is defined as the seperation of compounds using an electric current.

Let's not forget the electrolyte. Gotta have it for electrolysis.

Originally Posted by Mercedes Benzene

Rust on a car is a form of spontaneous oxidation. The electrons move as a result of a chemical change. The movement of electrons in a redox reaction is entirely different (and opposite) from running a current through a substance. Now, if there is a significant amount of ions in the rain water when the current is passed from the electrodes, some decay may be present, but in your application, it's doubtful that anything significant would occur. You're not using iron, and it seems that your alloys would be fairly unreactive.

That's my two cents.

Correct on the 'need rain' idea. However, pretty much any metal except gold can be broken down by electrolysis. In the marine environment, boat motors, rudders, and keels are fitted with sacrificial anodes made ususally of zinc which is less noble than other metals found in the boat and so 'goes first' as it were to the ravages of electrolysis.

I suggest sacrifical anodes for the track as well. If electrolysis is occuring, the anode breaks down and it's obvious; then you simply replace it.

[freeztar]

Great point Turts!
That reminds me of a show I saw a few months back. It was an episode of "Dirty Jobs" in which the poor sod had to delve into a levee to repair the worn annodes which were bolted on plates of metal lining the interior. They take the decay (electrolysis) and are replaced regularly. The steel walls remain intact.