Half a croissant, on a plate, with a sign in front of it saying '50c'
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Coated Diamond Coatings

One monatomic layer of fluorine, please.
(+1, -1)
  [vote for,

In another Idea I mentioned a specific use for diamond coatings (link). I mentioned that diamond is a non-stick material, but in an annotation [Ling] mentioned that diamond can attract grease. Obviously this must be fixed!

One of the things that has bothered me, in my imaginations about all the intermolecular bonds of something like diamond, is, "What about the potential for bonds at the surface of the substance?" In many substances those surface atoms simply latch onto whatever atoms or molecules happen by (metals acquire a thin oxide coating), but what do the carbons do, at the surface of a diamond? I'm pretty sure that they are willing to form double-bonds with adjacent carbons (since carbon does double-bonds so easily). But I'm not positive. PERHAPS some of them just "dangle", but in Chemistry, dangling bonds don't usually stay unattached very long.

The fact that diamond attracts grease would fit with a scenario in which diamond has available molecular bonds at its surface. To remove the attraction, the bonds must be tied down permanently.

Well, the most permanent chemical bond a carbon atom can form is with a fluorine atom. That famous substance Teflon is a chain of carbon atoms surrounded by fluorines. And we all know how resistant Teflon is, to stuff sticking to it.

So, whenever we coat something with diamond, to give it surface hardness and other nice properties -- but especially when we want to use the inertness of diamond -- let us also apply just a whiff of fluorine gas. The Idea is that the fluorines will break up those double-bonds at the surface of the diamond, and form a layer. This layer will greatly enhance the chemical inertness of the diamond, because the fluorines bind tightly, and are physically big enough to not let any other atoms get at the carbons.

Vernon, Aug 20 2004

Diamond-Coated Heat Exchangers http://www.halfbake...20Heat_20Exchangers
As mentioned in the main text. [Vernon, Oct 04 2004]

Fluorinated Diamondlike Carbon Coatings http://www.nasatech...Oct01/MSC22364.html
from nasatech.com [st3f, Oct 04 2004]


       Sure. But what will protect the fluorine?
Worldgineer, Aug 20 2004

       Seems sensible to me, +
scubadooper, Aug 20 2004

       Sounds good.
DesertFox, Aug 20 2004

       "what will protect the fluorine?"   

       Heh. Actually very few substances are able to break up the carbon-fluorine bond. NOTHING can steal the carbon from the fluorine, but a few metals (ELEMENTAL sodium, potassium, and a couple others) can steal the fluorine from the carbon. If that happens, then likely the carbons will either revert to double-bonds at the surface of the diamond, or some exotic substance like cesium carbide might form as the new layer at the surface of the diamond. I THINK the diamond will not otherwise be affected.   

       I suppose that instead of seeking an all-purpose coating, we seek to protect the diamond with whatever is appropriate for the conditions that are expected. A fluorine layer will be adequate for MOST conditions, however. And it's fairly rare to find conditions that include metallic sodium, to say nothing of those other elements.   

       [st3f], arrrrrgh! (Mostly baked!) Thanks for the link, though. 'Tis a good thing I have specified "diamond" and not "diamond-like" coatings. :)
Vernon, Aug 20 2004

       Yeah, just what we need. More Fluorocarbons.
GutPunchLullabies, Aug 20 2004

       Mostly baked? Perhaps a little more than half baked? It belongs here. +
sartep, Aug 20 2004

       [GutPunchLullabies], fluorocarbons are OK. CHLOROcarbons, however, are somewhat less stable, and can release chlorine that messes around in the ozone layer.
Vernon, Aug 21 2004


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