Edouard Bastarache Inc. on sat 21 jul 07
----- Original Message -----
From: Edouard Bastarache Inc.
To: Karen Latorre
Sent: Friday, July 20, 2007 11:35 PM
Subject: Re: Winkelmann and Schott COE Figures AND
an INSIGHT question on COE
Karen,
Edouard, thanks for the links. Interesting
information.
"Welcome"
A question on the information at the links you
provided: Where I see the
term "Bass" on the graphs Edouard, this is your
method of measurement,
correct?
"Yes, it is the method I used at the time of the
project"
Regarding the information at the two links, the
following information is
interesting: "It should be remembered that these
expansions (dilatations)
are valid only if the « Custer added material »
mixture is completely melted
(or transformed into a frit). This is not valid
for a paste where there
would remain nonmolten crystalline materials and
badly amalgamated in the
vitreous phase."
The tests I'm conducting are using a base of 100%
frit from two different
suppliers. The two frits that are in question are
from the same supplier. I
would expect that the frits we use in glaze
formulation have been fully
melted as part of the fritting process. Is this a
correct assumption, or is
there a possibility that the frits from this one
supplier have not achieved
a true full melt and therefore have some
un-amalgamated portions in the
material (and thereby the calculated COE values
are not matching reality)?
While I don't think this is what's causing the
discrepancy (if it were, I'd
expect the INSIGHT COE values to also be off, but
they're not), reading your
information caused me to wonder about this point.
"Well, the COE calculation applies to melted
mixtures.
Frits are "already melted mixtures."
You can verify this using GlazeChem which
seemingly uses Winkelmann's
method`:
Ferro frit #3110 :
Na2O 0.64 Al2O3 0.09 SiO2 3.03
K2O 0.06 B2O3 0.10
CaO 0.29
Alumina:Silica ratio is 1.00:32.01
Neutral:Acid ratio is 1.00:15.78
Alk:Neut:Acid ratio is 1.00:0.19:3.03
Expansion: 104.2 x 10e-7 per degree C
Oxides causing abnormal expansion:
B2O3
Or use any other programme you have access to,
you will find a COE according to the method used.
Using Chris Hogg's free programme I get this
for the same material :
RTE (0-500 C) = 0.53%
David Hewitt gave me the name of themethod used in
Hogg's
programme but I do not recall the name, and David
is not with us anymore to help us."
The other interesting information is that W&S
values are only valid from
20 to 100C whereas others are valid from 20 to
400C. Does this mean that the
W&S values don't extend well into the higher
temperature levels and
therefore using them to guess at the
compatibility of a glass to glass
interface would lead to incorrect values? This
could be the source of the
discrepancy I'm seeing between the W&S values and
the INSIGHT values of COE.
"Right, in the case of Winkelmann' s. I dont know
about Schott's"
Is there information somewhere on the processes
used to measure the
various sets of COE data? I don't think this is a
factor in what I'm seeing.
I'm just curious.
"No"
"I translated Smart's report on Appen's method to
calculate the COE,
but it is not uploaded yet, I also made
calculations by hand to get
familiar with it" :
http://perso.orange.fr/smart2000/dilatation.htm
Later,
Edouard Bastarache
Le Français Volant
The Flying Frenchman
Sorel-Tracy
Quebec
http://perso.orange.fr/smart2000/livres.htm
http://www.pshcanada.com/Toxicology.htm
http://www.ceramique.com/cerambooks/rayons/technologie.php
http://www.flickr.com/photos/30058682@N00/
http://myblogsmesblogs.blogspot.com/
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