"Don Wilkins" wrote in message
...
On 8 Feb 2004 08:30:48 -0800, jim rozen
wrote:

,;In article , Ed
Huntress
,;says...
,;
,;"Industrial ceramics are commonly understood to be all industrially
used
,;materials that are inorganic, nonmetallic solids. Usually they are
metal
,;oxides (that is, compounds of metallic elements and oxygen), but many
,;ceramics (especially advanced ceramics) are compounds of metallic
elements
,;and carbon, nitrogen, or sulfur."
,;
,;This portion of your excellent discussion is what does it for me,
,;the fact that cemented carbides are composed to some large degree
,;of cobalt metal means that I would tend to shy away from the
,;'ceramic' label. Though I have to agree that the issue is a
,;confusing one - here the thing's name really depends on who
,;is doing the describing: physicist, ceramist, chemist, machinist,
,;etc.

Actually the cobalt content of cemented tungsten carbide is small
compared to the WC and other carbides. The reason cobalt is used is
that it wets the surface of WC and doesn't run wild dissolving the
carbide. Nickel or iron or a lot of other elements would be cheaper.

How you label these materials certainly will depend on your
background. I thought Ed and I might agree but it ain't gonna happen.
That makes no difference because we are both correct in the
environment in which we work.

Oh, I don't think we disagree, Don. I'm just being contrary. g

In trying to clarify something like this it's often more important to
identify the points of disagreement than those of agreement. I don't write
to explain things to people like you, who know more about the chemistry of
it than I'll ever know. I write to make as clear as I can the things that
are relevant and distinctive to the machinists and people with an
applications-engineering interest in materials.

So don't think we really disagree. My point there was that your
understanding of ceramics is based on a chemist's needs and understanding,
which is at the opposite pole from a ceramicist's needs and understanding.
People who do metalworking with these materials are somewhere in the middle
of those two extremes.

Tungsten carbide is a misunderstood material, lost in jargon and convention
within the metalworking trades. I've tried to deal with that and explain it
to a magazine audience for roughly 30 years, although not quite in the terms
we've been using here. Having your POV on it is extremely helpful -- for the
contrasts more than the similarities, actually. One could make a case that
it's a lack of confrontation between the different views on this subject
that have helped to muddy the waters over the last 80 years.

Now, if we had a potter here on the NG, we'd really be able to put some
perspective on it. g

Ed Huntress