James Freeman on mon 27 aug 12
Everything you ever wanted to know about pyroxines as grown in nature:
http://www.minersoc.org/pages/Archive-MM/Volume_39/39-307-768.pdf
The charts of temperature and pressure start about 1/3 of the way down.
The pressures discussed are about a zillion times too high for us (15 kBar
is the lowest I saw!), but perhaps there is a way to derive a suitable
answer.
Here's info on a specific pyroxene grown in ordinary lab furnace
temperatures and pressures: http://144.206.159.178/ft/566/11311/217423.pdf
Too deep for my sleep deprived brain to digest just now. Happy to dig up
more for you, if you wish. Enjoy!
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Mon, Aug 27, 2012 at 9:13 PM, Robert Harris wro=
te:
> A technical question for once!
>
> I'm doing some experiments with a tenmoku that is showing some interestin=
g
> pyroxene effects, and I'm exploring their formation. Increasing magnesium
> concentration just increases number of crystals rather than size (althoug=
h
> size also increases slightly).
>
> I was wondering if anyone knew at what temperature pyroxene crystals grew=
?
> I already slow cool between 2150 and 1400 at 90F/hr (I cool from 2300 to
> 2150 @200F), so I was wondering if anyone had a good feel for a hold temp
> that would increase pyroxene crystal size.
>
> Thanks
> Robert
>
> --
> ----------------------------------------------------------
>
Steve Slatin on mon 27 aug 12
Robert -- IIRC, Bowen's reaction series is the key to finding=3D0Athe olivi=
ne=3D
-pyroxene-feldspar melting points.=3DA0 I don't have=3D0Amy references with=
me =3D
or I'd try to run it down.=3D0A=3DA0=3D0ABest --=3D0A=3D0ASteve Slatin -- =
=3D0A=3D0A=3D0AN4=3D
8.0886450=3D0AW123.1420482=3D0A=3D0A=3D0A________________________________=
=3D0A=3DA0=3DA0=3D
=3D0A=3DA0 =3D0AA technical question for once!=3D0A=3D0AI'm doing some exp=
eriments w=3D
ith a tenmoku that is showing some interesting=3D0Apyroxene effects, and I'=
m =3D
exploring their formation. Increasing magnesium=3D0Aconcentration just incr=
ea=3D
ses number of crystals rather than size (although=3D0Asize also increases s=
li=3D
ghtly).=3D0A=3D0AI was wondering if anyone knew at what temperature pyroxen=
e cr=3D
ystals grew?=3D0AI already slow cool between 2150 and 1400 at 90F/hr (I coo=
l =3D
from 2300 to=3D0A2150 @200F), so I was wondering if anyone had a good feel =
fo=3D
r a hold temp=3D0Athat would increase pyroxene crystal size.=3D0A=3D0AThank=
s=3D0ARo=3D
bert
Robert Harris on mon 27 aug 12
A technical question for once!
I'm doing some experiments with a tenmoku that is showing some interesting
pyroxene effects, and I'm exploring their formation. Increasing magnesium
concentration just increases number of crystals rather than size (although
size also increases slightly).
I was wondering if anyone knew at what temperature pyroxene crystals grew?
I already slow cool between 2150 and 1400 at 90F/hr (I cool from 2300 to
2150 @200F), so I was wondering if anyone had a good feel for a hold temp
that would increase pyroxene crystal size.
Thanks
Robert
--
----------------------------------------------------------
Steve Slatin on tue 28 aug 12
Robert -- James' comment finally got the penny to drop.=3DA0 There's=3D0Aan=
app=3D
let at http://melts.ofm-research.org/Applet/applet_download.html=3D0Athat y=
ou=3D
can use to calculate virtually all the interesting melting points.=3D0A=3D=
A0=3D
=3D0AIt's free, but remember to adjust to standard pressure before beginnin=
g,=3D
=3D0Aor you'll get garbage results.=3D0A=3D0ASteve Slatin -- =3D0A=3D0A=3D0=
AN48.0886450=3D
=3D0AW123.1420482=3D0A=3D0A=3D0A----- Original Message -----=3D0AFrom: Jame=
s Freeman =3D
=3D0ATo: Clayart@LSV.CERAMICS.ORG=3D0ACc: =3D=
0ASent=3D
: Monday, August 27, 2012 8:22 PM=3D0ASubject: Re: Pyroxene crystallisation=
=3D
=3D0A=3D0AEverything you ever wanted to know about pyroxines as grown in na=
ture=3D
:=3D0Ahttp://www.minersoc.org/pages/Archive-MM/Volume_39/39-307-768.pdf=3D0=
A=3D0A=3D
The charts of temperature and pressure start about 1/3 of the way down.=3D0=
AT=3D
he pressures discussed are about a zillion times too high for us (15 kBar=
=3D
=3D0Ais the lowest I saw!), but perhaps there is a way to derive a suitable=
=3D
=3D0Aanswer.
ivor and olive lewis on tue 28 aug 12
Dear Robert Harris,
Without information about your ingredients my guess is that you are toying
with an Iron oxide rich system based on K2O-CaO-MgO-Al2O3-SiO2.
Looking at the phase diagrams for a simplified system by eliminating K2O an=
d
Fe2O3 it would seem that you are cooling through the Quaternary Piercing
Points (Lowest freezing or solidification point similar to a Eutectic point=
)
before your crystals have chance to grow.
My immediate suggestion would be to go for an Isothermal Transformation at
2200F and hold for at least an hour. If that is unsatisfactory re-test with
a hold at 2100F. You may need to think about using draw rings to check on
progress.
Regards,
Ivor Lewis,
REDHILL,
South Australia
James Freeman on tue 28 aug 12
Robert...
Here is an even better reference, specifically about growing pyroxenes in a
ceramic glaze:
http://www.sciencedirect.com/science/article/pii/S002230930400883X
Apparently all of the scientific work has been done for you, and it is
yours for a mere $31. I regret that I was unable to find you a free copy
of the article online, but a college library, if you have access, can
likely order it for you. Don't we all read The Journal of Non-Crystalline
Solids on a regular basis?
Take care.
...James, your helpful reference librarian
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Mon, Aug 27, 2012 at 9:13 PM, Robert Harris wro=
te:
> A technical question for once!
>
> I'm doing some experiments with a tenmoku that is showing some interestin=
g
> pyroxene effects, and I'm exploring their formation. Increasing magnesium
> concentration just increases number of crystals rather than size (althoug=
h
> size also increases slightly).
>
> I was wondering if anyone knew at what temperature pyroxene crystals grew=
?
> I already slow cool between 2150 and 1400 at 90F/hr (I cool from 2300 to
> 2150 @200F), so I was wondering if anyone had a good feel for a hold temp
> that would increase pyroxene crystal size.
>
> Thanks
> Robert
>
> --
> ----------------------------------------------------------
>
Robert Harris on tue 28 aug 12
Ivor - You're absolutely right about the system we're dealing with. Also,
magnesium is both limiting, and obviously essential to crystal growth.
Increasing magnesium concentration increases both size (to a small extent)
and number of crystals - to an extent that they become ugly rather than an
attraction. This would imply to me that growth is being restricted mostly
by magnesium concentration.
Ideally I'm trying to reduce the number of nucleation events, while
allowing the crystals to grow slightly larger - in a slightly magnesium
restricted environment.
I definitely think the temperatures you talk about are useful though. I'll
let you know how it goes.
Thanks again
Robert
Without information about your ingredients my guess is that you are toying
> with an Iron oxide rich system based on K2O-CaO-MgO-Al2O3-SiO2.
>
> Looking at the phase diagrams for a simplified system by eliminating K2O
> and
> Fe2O3 it would seem that you are cooling through the Quaternary Piercing
> Points (Lowest freezing or solidification point similar to a Eutectic
> point)
> before your crystals have chance to grow.
>
> My immediate suggestion would be to go for an Isothermal Transformation a=
t
> 2200F and hold for at least an hour. If that is unsatisfactory re-test wi=
th
> a hold at 2100F. You may need to think about using draw rings to check o=
n
> progress.
>
> Regards,
>
> Ivor Lewis,
> REDHILL,
> South Australia
>
--
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