Jess McKenzie on thu 26 nov 09
Two items:
1. Thanks to Ivor for that reference. Out here in
the provinces, we are able to obtain such books only
through purchase or through our local public library
via interlibrary loan. Right now, we are waiting
word on a book recommended by Lou Turner:
Introduction to Phase Equilibria in Ceramics by
Clifton Bergeron and Subhash Risbud, and we don't
want to antagonize our librarian. But Ivor's
recommendation comes next.
2. Speaking as a "non-ceramic chemist," I think Earl
Krueger's point is well taken--in these systems
(glazes, etc) the intimacy of components is known to
affect melting rates. Thus to obtain precise data,
physical chemists in the 1800s derived the original
eutectic point data by studying the freezing points
of melts, rather than the melting points of solid
mixtures. Components of a molten mix--about as
intimate as one could hope for--yielded the most
reproducible data sets.
~jess
Date sent: Thu, 26 Nov 2009 10:54:39 +1030
Send reply to: ivor & olive lewis
From: ivor & olive lewis
Subject: Re: eutectics and more....
To: Clayart@LSV.CERAMICS.ORG
[ Double-click this line for list subscription
options ]
Dear Earl Krueger,
You make a valid point.
<<...One thing I have not seen discussed in the
recent conversations
on melting/eutectics is the degree of intimacy of the
components of
the eutectic...>>
From the Oxford Dictionary of Science and other
sources of information
there are several things to consider which apply to
the Eutectics
featured in Phase Equilibrium Diagrams of Oxide
Systems.
1. A Eutectic Substance is a Solid Solution or an
Alloy.
2. It is crystalline.
3. Its particulate components will be in the form of
Ions (atoms or
groups of atoms that have gained or lost electrons)
Atoms or
Molecules.
4. One particle, as defined above, in a solid
solution is replaced by
a different Ion, Atom or Molecule.
5. Replacement takes place so that substitution
happens at crystal
lattice sites.
So you might say intimacy is at the atomic level,
which seems to rule
out ingredients of a normal glaze recipe batch. Frits
are out because
they are usually amorphous or glassy. Nepheline
Syenite seems to
qualify. Potash felspar would not, it undergoes a
Peritectic reaction
(A whole new ball game. Lets not go there. But it is
important)
Please read my note to Jess McKenzie about two
varieties of Eutectic.
You might research Arthur S. Watts. Much of what he
wrote in the
middle of last century is published by the American
Ceramics Society.
His work is based on results derived from testing for
Deformation
Eutectic Mixtures.
Best regards,
Ivor Lewis,
Redhill,
South Australia
Carolyn Boeri on fri 27 nov 09
What I like about this conversation is that it demonstrates the Tao of
Physics. And yes I would like to experience the tao of molten glass, the
ultimate intimacy. Now That is another one of the book titles I am saving,
for my next life.
tata,
Carolyn
----- Original Message -----
From: "Jess McKenzie"
To:
Sent: Thursday, November 26, 2009 10:53 PM
Subject: Re: eutectics and more...
> Two items:
>
> 1. Thanks to Ivor for that reference. Out here in
> the provinces, we are able to obtain such books only
> through purchase or through our local public library
> via interlibrary loan. Right now, we are waiting
> word on a book recommended by Lou Turner:
> Introduction to Phase Equilibria in Ceramics by
> Clifton Bergeron and Subhash Risbud, and we don't
> want to antagonize our librarian. But Ivor's
> recommendation comes next.
>
> 2. Speaking as a "non-ceramic chemist," I think Earl
> Krueger's point is well taken--in these systems
> (glazes, etc) the intimacy of components is known to
> affect melting rates. Thus to obtain precise data,
> physical chemists in the 1800s derived the original
> eutectic point data by studying the freezing points
> of melts, rather than the melting points of solid
> mixtures. Components of a molten mix--about as
> intimate as one could hope for--yielded the most
> reproducible data sets.
>
> ~jess
>
>
> Date sent: Thu, 26 Nov 2009 10:54:39 +1030
> Send reply to: ivor & olive lewis
>
> From: ivor & olive lewis
>
> Subject: Re: eutectics and more....
> To: Clayart@LSV.CERAMICS.ORG
>
> [ Double-click this line for list subscription
> options ]
>
> Dear Earl Krueger,
>
> You make a valid point.
>
> <<...One thing I have not seen discussed in the
> recent conversations
> on melting/eutectics is the degree of intimacy of the
> components of
> the eutectic...>>
>
>
>
> From the Oxford Dictionary of Science and other
> sources of information
> there are several things to consider which apply to
> the Eutectics
> featured in Phase Equilibrium Diagrams of Oxide
> Systems.
>
>
>
> 1. A Eutectic Substance is a Solid Solution or an
> Alloy.
>
> 2. It is crystalline.
>
> 3. Its particulate components will be in the form of
> Ions (atoms or
> groups of atoms that have gained or lost electrons)
> Atoms or
> Molecules.
>
> 4. One particle, as defined above, in a solid
> solution is replaced by
> a different Ion, Atom or Molecule.
>
> 5. Replacement takes place so that substitution
> happens at crystal
> lattice sites.
>
>
>
> So you might say intimacy is at the atomic level,
> which seems to rule
> out ingredients of a normal glaze recipe batch. Frits
> are out because
> they are usually amorphous or glassy. Nepheline
> Syenite seems to
> qualify. Potash felspar would not, it undergoes a
> Peritectic reaction
> (A whole new ball game. Lets not go there. But it is
> important)
>
>
>
> Please read my note to Jess McKenzie about two
> varieties of Eutectic.
> You might research Arthur S. Watts. Much of what he
> wrote in the
> middle of last century is published by the American
> Ceramics Society.
> His work is based on results derived from testing for
> Deformation
> Eutectic Mixtures.
>
>
>
> Best regards,
>
>
>
> Ivor Lewis,
> Redhill,
> South Australia
>
>
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