Re: [ATM] Fwd: [Fwd: [atm_free] Effect of pH on polishing fused silica was Re. Session 24...]

[Dave Smith <smithersscope@yahoo.com>]

Hi Dominic,
CeO reduction...That's a good thought. My gut response
was reduction of the organic lap moieties (complex
sugars and carbs); seems like they'd be more readily
reduced than the CeO, but I'm a biochemist, not a
chemist.
What I can't figure is why reduction of carbs would
increase drag? Are reduced carbs "stickier" substances
by nature? If so, then is it essentially the same
effect as increased heat?
Seems to me pH would be easier to control (especially
once the mirror and lap are in motion) than heat. I
would expect the drag to respond in a sigmoidal
fashion if it's a true pH effect (the old Bohr
principle). In other words as the pH decreases I
suspect the range where one would go from normal drag
to "tremendous" drag to be very narrow. It would be
tricky to nail down reproducibly. And if it truly is a
matter of lap composition (in terms of chemical
makeup), I'd bet no two laps behave the same.
Also seems logical that that new synthetic lap
material might be more well-behaved than traditional
pitch (with respect to the pH effect), if it really is
a "known" mixture.
...just thinking out loud.
Dave

--- Dominic-Luc Webb <dlwebb@canit.se> wrote:

> On Thu, 30 Aug 2007, Guy Brandenburg wrote:
> 
> > Interesting comments on pH levels and polishing
> with CeO2
> 
> Hmmmm... sounds like this is giving a reduced form
> of CeO...
> 
> Dominic
> 
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
> 



       
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