iandol on fri 23 nov 01
Dear Paul,
You ask and silica mix:>
The Phase diagram for this system seems to suggest that there is no =
Eutectic for the substances Corundum and Quartz (Otherwise Silica and =
Alumina) which are but is seems there is a chemical reaction between =
them if you can melt the silica and dissolve the alumina in the melt, =
you will create Mullite on cooling. The diagram shows a Eutectic between =
Mullite and Silica at 1595 deg Celsius and another between Mullite and =
Corundum at ~1850. Pretty hot stuff!!(That may be a shock to those who =
recite current rubric)=20
<standards - Silica, Alumina, calcium , Sodium and/or Potassium .>>
Again, it is difficult to get the materials needed for mixtures which =
would take advantage of any Eutectic Melting points. The only one I have =
made so far has been thanks to Michael Banks who supplied me with the =
approximately right mineral to mix with Wollastonite and silica. That =
was for 1170 in the CaO-Al2O3-SiO2 System.=20
For example, if you really need to use mixtures which may melt at low =
eutectic temperatures, you would need to get hold of and weigh out the =
right proportions of Potassium Tetra-Silicate, Quartz and Potash Felspar =
to imitate the 710 deg Celsius point.
Since I have an article under review which deals with reading phase =
diagrams, I am not willing at the moment to say more, but if you want to =
find some useful mixtures of a Genre called "Deformation Eutectics" =
(which are ignored by recent writers of important books and a very =
different beast from the points on Phase Equilibrium Diagrams), contact =
me "off list" and I will let you have some information.
Best regards,
Ivor Lewis. Redhill, South Australia
LOGAN OPLINGER on sat 1 dec 01
To: Paul Taylor (and All),
This is the first chance I've had to reply to your posting. I cannot claim any expertise re: making frits or with ceramic eutectics. What I can offer is possible directions in which to look for information.
The book CERAMIC SCIENCE for the POTTER, 1972, by W. G. LAWRENCE has a chapter (17) on Phase Equilibria Diagrams, and two tables in Appendix A-2 on binary (two component) and ternary oxide eutectics. I won't repeat the compositions or melting points here because of possible copyright restrictions. The reference cited is PHASE DIAGRAMS for CERAMISTS by LEVINE, E. M. et. al., 1964, published by the American Ceramics Society.
I did a web search on the reference cited, and found several university libraries (U. S.) that have the ACS series in their technical reference sections. Amazon.com also has copies for sale, but very pricy!
Another source of information is THE CHEMICAL FORMULARY, 1952, by BENNETT, H. ed. In Vol. IX under Ceramics, Glass, & Cements are several formulations for frits and enamals (some, but not all have the melting points given), and also a recipe for a crucible clay body. Other volumes also have some formulations for enamals, frits & glazes. (Our University of Guam Library has only the first 10 volumes, of the 35 volume series, but even these are a wealth of information on everything from acid resistant ceramics & paints, artists paints to cosmetics to food recipes to waterproofing compounds.)
You may also be able to find some useful information at the following web site:
http://www.uni-wuerzburg.de/mineralogie/links/matscience/matscience.html#ceramics
and
http://www.uni-wuerzburg.de/mineralogie/links/glossaries/databases.html#Helpful
I must go now, the UOG library closes early on Saturdays. If I may be of more help, please contact me through my e-mail adress.
Logan Oplinger
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