[NewCandle] Stretching (and hiding) nanosquiddies

[Horace Heffner]

Slight correction.


On Feb 22, 2009, at 10:55 AM, Nick Reiter wrote:

>
> Hi Keith,
>
> Rusty wheels slowly turn, and squeak, but yes, very good, I am  
> seeing the analogy.  Hm.  I suppose that there could be some odd  
> current paths then, if one considers that the aluminum foil rolls,  
> in their native state, have hidden surfaces aplenty, where the  
> ingress of electrolyte / salt water is limited in rate.
>
> Well, by all means, jazz that foil with a battery I shall.
>
> n

I think corrosion is often driven by differing but closely located  
surface elements creating very short range electrolytic currents via  
their differing electronegativities.  Cathodic protection works if  
the potential of the eroding material is raised enough to make all  
the elements on the surface cathodic.

One interesting thing about this is that the relatively cathodic  
spots on the surface can take on deposits of similar metal from  
solution, and, providing the gradient is only sufficiently large at  
sharp tips,  thus can grow dendrites or fibers - all without current  
being supplied.  I think reducing surface potential to the extent a  
point is not needed to add material, but rather material is deposited  
at all points, would tend to suppress dendrite formation and produce  
more club-like protrusions or other geometries, and in the extreme  
tend to create a fairly uniform covering.

If this is true then carefully varying electrolysis potential, even  
across a very small small range, could increase of decrease the rate  
and type of dendrite formation.

Best regards,

Horace Heffner
http://www.mtaonline.net/~hheffner/





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