[NewCandle] More pics from Nick

[Horace Heffner]

Nick, my experience with anode glow is that, above the threshold  
operating voltage, the glow intensity is proportional to current  
density.  A small electrode will glow brighter than a large one at a  
given current.  My experience with Zr, if I recall correctly, is that  
the conditioned surface had a higher resistance than aluminum and had  
to be run at a higher voltage to get the same current density.  When  
run in the even much higher voltage electrospark mode, the actual  
sparks on Zr were more energetic, kind of a bright white and smaller  
in diameter if I recall - I think due to the much stronger dielectric  
breakdown potential.  My memory is just not so good these days.

Best regards,

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



On Sep 13, 2008, at 1:06 PM, Nick Reiter wrote:

> Hi All,
>
> Thanks again, Keith,
>
> A couple of random observations:
>
> 1.  The oxide layer with the oxalic may be thinner, or
> it may be stressed differently or is denser... because
> when I snipped out a little bit for the SEM from the
> pop can bottom that had been run with the phosphoric
> acid (bright yellow glow) the oxide crust there seemed
> to break into the dehydrated mud flat cracked tiles.
>
> 2.  Snipping out a piece from the oxalic run can did
> not seem to fracture the "ceramic" coating.  In the
> low mag picture shown with this set, you'll see a
> large smashed in dimple to the top of the photo.  This
> was actually done intentionally with the tip[ of some
> stainless tweezers, to try to make a hole in the
> coating to get some glimpse of thickness.  As you can
> see, it sort of conformally smooshed out with the
> aluminum.
>
> 3.  Now back in the heyday of AGD work, I remember
> trying some strips of Zr foil in lieu of Al foil, in
> the AC version where the strips were suspended in a
> mason jar with weak baking soda solution.  I THOUGHT
> that I witnessed a very weak glow, and so presumed
> that Zr and maybe even Ti might act similarly to Al.
> Well, this morning, I was in at the lab, and I made a
> simulated pop can bottom from Zr foil, and set it up
> in the same geometry and style (DC supply, graphite
> cathode, with the Zr foil disc in the bottom of a
> styrofoam cup puck.)  Tried weak oxalic, phosphoric,
> and baking soda electrolytes, and could not get a
> glow.  SO maybe Zr acts differently than Al after all,
> or maybe I was just seeing things back in the day when
> I swore I saw a faint emission.
>
> Overall, the brightest bluest glow of any situation
> was with polished rod electrodes, and either DC power
> with helical stainless wire cathode, OR AC with two
> rods, and citric acid.  I can polish a pop can bottom
> in situ, though, and try that first... maybe I'll get
> a stronger blue with oxalic.
>
> N
> --- Keith Nagel <NewCandleAdmin at ipdiscover.com> wrote:
>
>> OK, new batch of pics, a bit delayed by some
>> foolishness on my part.
>>
>>
> http://www.kpnconsulting.com/newcandle/download/nick4.htm
>>
>> It's a shame the resolution poops out right when
>> things get interesting,
>> but that's basically a given with test equipment,
>> right???
>>
>> For what it is worth, the oxide layer seems very
>> disordered. Can
>> you polish a surface before you oxidize?
>>
>> K.
>>
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