disintegrating magnet in Aurum Cantus ribbon tweeter

[rastanearian]

I am in the process of replacing the ribbons in a pair of Aurum Cantus G3i-130 and have discovered that the shiny finish of the magnet has disintegrated into a fine magnetic powder. This deterioration has only occurred in the gap.
Much sticky tape later and I have cleaned the surface quite thoroughly.

Any comments on refinishing the gap surface? Yes? No? With what?
Perhaps it was just the finish that broke down and nothing further is required?

I want to be sure before I put the new ribbons in.

Thanks in advance for any advice.

 

[rastanearian]

Bueller? Bueller?

 

[bolserst]

My understanding is that it is the neodymium that is suseptible to oxidation, not the coating. The shiny nickle coating is there to protect the neodymium for oxidation. If you don't recoat it with some kind of protective layer, my guess it that the outer layer will continue to oxidize and turn into powder.

 

[rastanearian]

Great paper. Thanks.
It looks like I'll have to tear the whole driver apart to get at the magnets for a proper coating. They will need to be cleaned and thoroughly dried before any sealant is applied.
I am going to try a clear lacquer. It should do the trick.

Thanks again.