Breakdown of metal passivation layers

[Excom]

Hi All

I hope that someone where can help me out.

Let's assume that we take a piece of Al foil and a Pt wire and put them into an ionic solution. We then apply a voltage difference of 2 V between the two. Al(+) and Pt(-). After a few seconds the Al electrode starts to corrode. Nothing new about that but can anyone tell me what happens before the corrosion starts? I assume that the aluminum oxide is being removed. I am interested in figuring out what voltage that is needed to remove the aluminum oxide. And the kinetics of it.

If this can be described in a theoretical manner I will prefer that as I would like to compare different metal oxides at different voltages.

Thanks

Best regards
Tom

 

[Borek]

Way too many unknown factors for a theoretical treatment, experiments are a way to go.

 

[Excom]

Okay, thanks.

Instead of testing every metal oxide there must be a way of finding those oxides that are most likely to be the best.

Any idea of how to this?

 

[Borek]

to be the best

In what sense?

 

[Excom]

I want to find the best materials for passivating electrodes in ionic solutions.