On Sat, 22 Nov 2003 17:44:56 -0800, "Harold & Susan Vordos"
wrote:

Actually, I think that diamonds only sublime. I'm not convinced there's a
liquid phase of carbon, but I'm no chemist. This statement should open up
another round, yes?

At standard pressure, carbon does indeed sublime. At
some higher pressure carbon has a triple-point -- a
condition of pressure and temperature where a substance
exists in all three phases (solid, liquid, gas) simultaneously.

Sublimation 3642 C
Triple-point 4492 C

Since it has a triple-point, carbon has a liquid phase.

I don't happen to have the triple-point conditions for
carbon, but for a common substance (water) the conditions
are 273.16 K and 611.66 Pascals (0.0 C and .088715 psi).
The fact that the triple-point of the normal form of ice
is so near 0 C (actually a tiny fraction of a degree above it)
makes having a triple-point cell fairly easy. My father has
one that he picked up somewhere. Cool it to about the freezing
point and it has liquid water, ice, and water vapor all
existing simultaneously at about 1/100 of an atmosphere pressure.

--
--Pete
"Peter W. Meek"
http://www.msen.com/~pwmeek/

It is worse that that. Norton is the world leader in diamond film coating.

Dan


Gary Coffman wrote in message

Certainly the engineers at Norton, the world's largest
manufacturer of abrasives, know this.

Gary

I am always willing to learn. I knew one doesn't use Silicon Carbide
on steel, but had the wrong reason. Thanks for correcting me. Now I
am curious about the use of Silicon Carbide on other high strength
materials as Titanium. Not that I really need to know. Aluminum
oxide works well on Ti.

Thanks again,
Dan



"Harold & Susan Vordos" wrote in message


But I disagree with what was said about silicon Carbide.

Ah! Now we're talking. I have in my possession enough published
information to substantiate the fact that silicon carbide does, indeed,
dissolve in steel.

One must consider that at the point of contact, terrific heat is generated,
so the rules sort of change. Because of the intense heat, there is dulling
of the grain attributed to dissolving into steel. I'll gladly forward a
scan of the information to you. One of my references is a soft bound
booklet by Norton Company, copyright 1951. It is titled Lectures on
Grinding. On page 19 there are two paragraphs that describe the accepted
theory of the reaction.

Anyone interested in a scan is invited to request it. I'll get it out as
quickly as possible.

Harold

I thot yours was a good example of "if you can't dazzle them with
brilliance, baffle them with bull****".

Whatever.

Out.

(gradstdnt) wrote

John Doe posses an outstanding ability to describe his reasoning
with such detail and yet make such a technical issue clear to the
layman. He makes such a difficult task look so easy. A true
indicator of a real porfessional. We should applaud Mr. Doe for
his significant contribution to this thread.

John Doe wrote in message
8...
(gradstdnt) wrote

You need to look at some very basic chemisty behind the diamond.

BZZZT!

In article , Dan Caster says...

It is worse that that. Norton is the world leader in diamond film coating.

Worse, or better? :^)

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

jim rozen wrote:

In article , George E. Cawthon says...

On sublimation of diamond. Although 3550 degree C is listed
as a melting point in several references some of the same
references indicate that it actually sublimes. Still, these
references don't fit what appears to be a valid reference
that says diamond breaks down at a much lower temp, and that
reference gave breakdown temps in the presence of oxygen and
in the presence of nitrogen. I believe that was in one of
Bob Powell's references.

At this point you are in the range of solid state chemistry.

I used to work with guys who 'did' solid state chemistry,
for things like crystaline lighting phospors, and for
ZrOx oxygen sensors. This was at GTE labs in waltham, mass.

Some of the guys had PhDs, and others simply worked in the
lab and wore those funny pointy hats with stars and plantets
on them. They also tended to have jars around with strange
labels, eye of newt and jaw of toad, etc. It's a very
strange discipline and most of it is art, to go along with
a small amount of science. Things like 'fluxes' that
work at 1600 deg C.

All I *can* say with some certainty is that a) one should not
attempt to intuit the results of an experiment based on
ordinary chemistry rules, and b) trust the experience of
those who have worked in the field.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

My physical chemistry is pretty old. My first chem book was
by Linus Pauling. Hell, all of my chemistry is pretty old
now. Lot's of it is still valid, but more and more new
knowledge seems to be less intuitive, which probably means
that our concept of some of the basics is wrong, or maybe
its just chaos. And yep, (a) got me in trouble.

So you are a non believer of covalent bonds and their ability to hold
the universe together. In any case, dismiss as you may and believe
whatever old wives tales may provide you. Just don't let Mrs. get her
rings too close to any iron as some believe they will readily dissolve.

John Doe wrote in message 8...
I thot yours was a good example of "if you can't dazzle them with
brilliance, baffle them with bull****".

Whatever.

Out.

(gradstdnt) wrote

John Doe posses an outstanding ability to describe his reasoning
with such detail and yet make such a technical issue clear to the
layman. He makes such a difficult task look so easy. A true
indicator of a real porfessional. We should applaud Mr. Doe for
his significant contribution to this thread.

John Doe wrote in message
8...
(gradstdnt) wrote

You need to look at some very basic chemisty behind the diamond.

BZZZT!

"George E. Cawthon" wrote in message
...
snip----
My physical chemistry is pretty old. My first chem book was
by Linus Pauling. Hell, all of my chemistry is pretty old
now. Lot's of it is still valid, but more and more new
knowledge seems to be less intuitive, which probably means
that our concept of some of the basics is wrong, or maybe
its just chaos. And yep, (a) got me in trouble.

I'm not so sure you're alone here, George. Since the theory of quantum
mechanics hit the scene, seems many of the rules no longer fit. The
recent PBS viewing of the string theory may enlighten all of us eventually,
assuming, of course, that we can understand just what they're proposing.
To me, makes no sense, but then I have a hard time finding my way home.
Not understanding something that even Einstein didn't shouldn't surprise me.
g

Harold

Okay I looked at the web site you referenced. And found C2H2
acetylene listed as a compound with a triple covalent bond. Which
according to you means it is very unlikely to have that bond break.
So why am I inclined not to have a container of acetylene compressed
to more than 30 psi? Does acetylene not burn?

Dan



(gradstdnt) wrote in message
http://people.deas.harvard.edu/~jone...lent_bond.html

Harold & Susan Vordos wrote:

"George E. Cawthon" wrote in message
...
snip----
My physical chemistry is pretty old. My first chem book was
by Linus Pauling. Hell, all of my chemistry is pretty old
now. Lot's of it is still valid, but more and more new
knowledge seems to be less intuitive, which probably means
that our concept of some of the basics is wrong, or maybe
its just chaos. And yep, (a) got me in trouble.

I'm not so sure you're alone here, George. Since the theory of quantum
mechanics hit the scene, seems many of the rules no longer fit. The
recent PBS viewing of the string theory may enlighten all of us eventually,
assuming, of course, that we can understand just what they're proposing.
To me, makes no sense, but then I have a hard time finding my way home.
Not understanding something that even Einstein didn't shouldn't surprise me.
g

Harold

Chaos theory and fractals mess me up enough. OTOH, I don't
know what I knew yesterday, or was it last week?

"Harold & Susan Vordos" wrote


The red wheels, if they are the ruby red, are aluminum oxide, just as the
old salmon colored wheels are.


Harold, I have wondered about that.... I have some fairly large ruby wheels
I obtained years ago, and without exception, they are excellent on hardened
steels... (by excellent, I mean cool cutting).... much better than the
white, and infinitely better than the grey aluminum oxide. I recently found
some for my surface grinder, and they also work very well on cast iron and
mild steel. Why are they red? Marketing hype? Why do they seem to work
better? I have other wheels just as coarse and soft acting, and they don't
do any where near as well.

Mark

I don't know how to tell you this, but a Ruby is AL203 == Aluinum Oxide in a
trigonal chrystal structure with a hardness of 9. Diamond being a hardness
of 10.


"Mark Winlund" wrote in message
...

"Harold & Susan Vordos" wrote


The red wheels, if they are the ruby red, are aluminum oxide, just as
the
old salmon colored wheels are.


Harold, I have wondered about that.... I have some fairly large ruby
wheels
I obtained years ago, and without exception, they are excellent on
hardened
steels... (by excellent, I mean cool cutting).... much better than the
white, and infinitely better than the grey aluminum oxide. I recently
found
some for my surface grinder, and they also work very well on cast iron and
mild steel. Why are they red? Marketing hype? Why do they seem to work
better? I have other wheels just as coarse and soft acting, and they
don't
do any where near as well.

Mark

Well, you told me, congratulations. That being said, the question is, is
the ruby color significant? Since all of the wheels I mentioned are
aluminum oxide, why is the ruby wheel better (in my experience) than the
others? The question was mostly directed at Harold, who is an acknowledged
expert on grinding.

Mark



"hg" wrote in message
.. .
I don't know how to tell you this, but a Ruby is AL203 == Aluinum Oxide in
a
trigonal chrystal structure with a hardness of 9. Diamond being a
hardness
of 10.


"Mark Winlund" wrote in message
...

"Harold & Susan Vordos" wrote


The red wheels, if they are the ruby red, are aluminum oxide, just as
the
old salmon colored wheels are.


Harold, I have wondered about that.... I have some fairly large ruby
wheels
I obtained years ago, and without exception, they are excellent on
hardened
steels... (by excellent, I mean cool cutting).... much better than the
white, and infinitely better than the grey aluminum oxide. I recently
found
some for my surface grinder, and they also work very well on cast iron
and
mild steel. Why are they red? Marketing hype? Why do they seem to work
better? I have other wheels just as coarse and soft acting, and they
don't
do any where near as well.

Mark

Mark Winlund wrote:

Well, you told me, congratulations. That being said, the question is, is
the ruby color significant? Since all of the wheels I mentioned are
aluminum oxide, why is the ruby wheel better (in my experience) than the
others? The question was mostly directed at Harold, who is an acknowledged
expert on grinding.

Mark

"hg" wrote in message
.. .
I don't know how to tell you this, but a Ruby is AL203 == Aluinum Oxide in
a
trigonal chrystal structure with a hardness of 9. Diamond being a
hardness
of 10.


"Mark Winlund" wrote in message
...

"Harold & Susan Vordos" wrote


The red wheels, if they are the ruby red, are aluminum oxide, just as
the
old salmon colored wheels are.


Harold, I have wondered about that.... I have some fairly large ruby
wheels
I obtained years ago, and without exception, they are excellent on
hardened
steels... (by excellent, I mean cool cutting).... much better than the
white, and infinitely better than the grey aluminum oxide. I recently
found
some for my surface grinder, and they also work very well on cast iron
and
mild steel. Why are they red? Marketing hype? Why do they seem to work
better? I have other wheels just as coarse and soft acting, and they
don't
do any where near as well.

Mark




the best grinder i ever had: did not get red until after she started
up.. boy did she get red......