[NewCandle] Salt water aluminum roll hydrolysis update

[Nick Reiter]

Thanks Keith - I just sent you over some deelightful squidiforms...

n


> Thanks for the update.
> 
> If you have new pics, send them to this email address,
> rather than the
> old gis account. I stopped using them when I moved, and
> frankly I
> am loathe to ever use an ISP provided email address again
> because
> ISPs are unwilling to provide any kind of forwarding when
> you cancel
> service. These domains ( especially k at kpnconsulting.com
> ) will remain
> for as long as I will remain.
> 
> By their nature, corrosion processed inply a voltage
> gradient. Where
> the cathodic region ends up depends on a lot of things, but
> mostly
> geometry of the corroding metal. I would expect regions
> inside the
> roll, where corrosion is minimal, to be slightly negative,
> as you
> see. The full gradient will be much larger, but difficult
> to measure
> as it is on a micro scale rather than the macro scale of
> your entire
> roll. For example, edges tend to preferrentially corrode,
> and thus are more
> positive.
> Protected inner areas will then be forced negative.
> 
> I too have a few tubes of aluminum / silver nitrate going
> from
> our last discussion. Mine are slowly producing hydrogen at
> the bottom of the tube, where there is still a large
> amount
> of bulk silver dendrites. There are patches of clean metal
> on the larger surface area samples, which are no doubt
> anodic.
> The smaller surface area sample remains covered with
> dendrites.
> A black "rust" has corroded back many of the dendrites.
> 
> I don't see any gray gell in this experiment, but I have
> certainly
> seen it before. I think it's aluminum hydroxide. I have
> for
> example seen it in a solution of aluminum nitrate using an
> aluminum cathode and aluminum anode, with a few volts
> applied
> across the two with a DC supply. What I assume has
> happened
> is that enough hydrogen has been generated to push the
> pH of the solution basic ( if those -OHs can't be released
> as
> O they've got to do something to the pH, huh? ).
> 
> The lozenge shape of my current aluminum samples was an
> attempt
> to control the macro voltage gradients, and I am gratified
> that
> they did do so. The lack of sharp corners prevent anodic
> hot spots from forming.
> 
> K.
> 


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