Is this electrolysis

[polk county]

Electrolysis happens when two different metals are immersed in water. I have an aluminum boat with what looks like a aluminum motor housing. Why is this happening?

Thanks for the help

 

[asdasc]

Re: Is this electrolysis

I could be wrong, but I don't think that tray is aluminum. I think it is what they call pot metal, but I don't really know what that is.

It looks more like salt corrosion, do you use it in fresh or salt water? Another option is that you had a chip in the paint and the corrosion just started at the exposed metal.

 

[ezeke]

Re: Is this electrolysis

It looks like the result of water getting between the paint and the metal which sets up this kind of electrolysis (galvanic corrosion). This is usually at least partially the result of poor bonding of the paint, but will be found even with very good finish around mating surfaces.

http://www.nymarine.ca/Tips.html


http://pubs.acs.org/doi/abs/10.1021/ie50346a013

More than you probably want to know: http://corrosion.ksc.nasa.gov/pubs/tm584c.pdf

 

[slasmith1]

Re: Is this electrolysis

Electrolysis happens when two different metals are immersed in water. I have an aluminum boat with what looks like a aluminum motor housing. Why is this happening?

Thanks for the help

Look at the annode in that picture it appears as if the paint goes under the annode. Your mating surface for the annode should have all the paint removed from it or the annode won't protect your motor.

 

[F_R]

Re: Is this electrolysis

None of us knows what the alloy of the aluminum is that they made the tray from. It may be an alloy that is just prone to salt water corrosion, no matter what. One thing for almost certain, it isn't pure aluminum.