juanruiz on fri 17 dec 99
This is kinda Important question:
Why would one want to add lithia to a body and how would this relate to
its microstructure?
Thanks in advance
Juan Ruiz
juanruiz13@hotmail.com
Michael Banks on sat 18 dec 99
By adding lithia to ceramic bodies (in the form of lithium carbonate,
petalite, spodumene etc.), it is possible to control the coefficient of
thermal expansion (CTE) of them from virtually any positive number down to
zero or even negative values. Low expansion (or even zero expansion) bodies
are useful for flame-proof ware, raku bodies and other applications, such as
solid propellant rocket nozzles.
Lithia reacts with alumina and silica in ceramic bodies in the solid state
(sintering) below the melting point to produce low-expansion crystalline
mineral phases. By carefully adjusting the Li2O/Al2O3/SiO2 ratios in the
recipe, virtually any lithium aluminosilicate mineral can be encouraged to
form by sintering. Bodies with zero or negative expansion result from
recipes approximating the composition of the lithium minerals eucryptite
(1:1:2), spodumene (1:1:4) and petalite (1:1:8).
Michael Banks,
Nelson,
New Zealand
> ----------------------------Original message----------------------------
> This is kinda Important question:
>
> Why would one want to add lithia to a body and how would this relate to
> its microstructure?
>
> Thanks in advance
> Juan Ruiz
Stephen Parry-Thomas on mon 20 dec 99
Hello Juan,
The following might help you as far as I am aware lithia mica, lepidolite are
used in clay bodies to make them "flameproof" - a loose term. A clay body
formulated with lithia will have a very low thermal expansion. One of the
problems with a clay body contains a large amount of lithia can be difficult
to use on the wheel, due to the type of crystal shape tends to compact. Most
of the worlds lithium ores are in the USA. I could give a more details if you
want them.
kind regards,
Stephen Parry-Thomas.
www.morrigancraftpottery.co.uk
Ron Roy on mon 20 dec 99
Better get as much info as possible before dabbling in lithia bodies -
Lawrence has a good section and so do Taylor and Bull in Ceramics Glaze
technology.
Bodies with very low expansion (useful for flame ware) can be made with
both lithium and magnesium.
If I remember correctly - you need to go higher than cone 10.
I would avoid lithium carbonate completely - it is somewhat soluble and
this can lead to different expansions in the same piece because the salts
will migrate.
This kind of technology requires good control and most of the glazes we use
will simple not fit low expansion bodies so new glazes have to be
developed.
RR
>----------------------------Original message----------------------------
>This is kinda Important question:
>
>Why would one want to add lithia to a body and how would this relate to
>its microstructure?
>
>Thanks in advance
>Juan Ruiz
>juanruiz13@hotmail.com
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Don Curtis on sat 25 dec 99
In a message dated 12/20/1999 4:25:17 PM Eastern Standard Time,
MorriganCP@cs.com writes:
<< www.morrigancraftpottery.co.uk >>
I was curious reading your recent comments on lepidolite. Do you know where
in the US you can purchase some? I have a glaze which I really like that
calls for some.
Thanks,
Don
DCurtis171@aol.com
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