[Hammarlund] Graphite is NOT an Abrasive...it is TOO!

[Barry L. Ornitz]

Kenneth Gordon wrote:

> That was myself, Barry, and despite your often superior
> knowledge and education, and despite your rather long
> explanation of why graphite can't possibly be an abrasive,
> my experience has proven quite otherwise.

Note that I deliberately did not name you.  Your experience is
in complete disagreement with the Society of Tribologists and
Lubrication Engineers, NASA, American Society of Mechanical
Engineers Tribology Division, etc.

> Every time I have used graphite to lubricate any metal
> bearing, including an automobile engine in which I used a
> (at the time) highly touted graphite/oil mix, the eventual
> result was severe wear.
>
> The automobile engine I am referring to was totally worn out
> within 10,000 miles because of this "lubricant", which
> "lubricant" didn't stay on the market long.

If this can be proven, why did you not go after the
manufacturer for damages?

I tend to distrust anything sold on hype such as these
products.  The PTFE containing automotive lubricants are sold
on hype too.  Unless you actually know the exact chemical
content of the oil, it could have contained natural graphite
instead of the far superior synthetic material.  If the engine
were already using oil, adding extra carbon to the oil just
means more burnt carbon in the engine.  Amorphous carbon, as I
noted earlier, along with diamond is abrasive.

> When I mentioned a geologist or gem-ologist, I meant Charles
> Knowles, recently retired from the University of Idaho from
> his position as the Idaho State Geologist. He, spontaneously
> one day, gave me an unasked for lecture concerning why
> graphite was an abrasive.

I know a Charles Knowles but perhaps not the same person.  But
as a geologist he is not a tribologist (and I am not either).
But I am very familiar with fluid flow and high shear fluid
properties as a chemical engineer.

> His explanation was almost as long as yours on why it is a
> lubricant.
>
> I don't remember the details, but as I recall, it had
> something to do with the fact that although the cleavage
> planes between some "sections" (my choice of word) of carbon
> in graphite are very loose and thus slide across one
> another, the carbon itself is hard. The end result,
> eventually, over a period of time, after you have broken
> nearly all the loose bonds, leaving only the strongly bonded
> carbon, is something very much like extremely fine
> carborundum.

If you had bothered to read the reference I posted, you should
have noticed this being discussed:

"Graphite itself does not undergo plastic flow. Graphite
loaded 90� to the basal plane would have a higher friction
(and slightly abrasive quality) than when loaded with the
basal or lubricating plane. Fortunately, all lamellas orient
under load to their lubricating attitude."

> I am sure Charles will be most happy to discuss the details
> with you or anyone else who asks.

Let me add the following quote from the same reference that
especially applies to a geologist.  As I noted in my earlier
post, natural graphite is normally far from pure.

"Graphite comes in the natural state or artificially produced
in an electric furnace. The best grades of mined graphite are
vein type which is structurally identical to artificial
graphite. Impure graphite of ANY type is unacceptable as a
lubricant."     {my emphasis}

> I will talk with him next week and, if possible, get his e-
> mail address for you.

I shall be happy to discuss the matter with him or anyone
else.

        73,  Barry L. Ornitz     WA4VZQ     ornitz@tricon.net