Re: ORGLIST: sintering temperature,

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From: Jacob Zabicky (zabicky$##$bgumail.bgu.ac.il)
Date: Tue Nov 13 2001 - 03:08:25 EST


Hello Bahman,

There is no such property as a defined "sintering temperature." Ceria is a
refractory ceramic oxide of very high melting point (2600 C), however,
sintering processes are carried out at lower temperatures. How low? --that
depends on the purity of the oxide and the particle size. Two examples:

a.Make a compressed pellet of a pure ceria fine powder (say 5 micrometer
particles) and heat it for a couple of days at 2400 C. The particles will
weld to their next neighbors and you'll end up with a solid body (it will
possibly crack because of residual stresses) where the original particles
disappeared. This is a sintering process that could also be carried out at
other temperatures below the m.p.

b. Make a compressed pellet of a mixture of ceria fine powder with a small
amount of another unreactive fine oxide powder (say both oxides consist of
5 micrometer particles) and heat it for a couple of days at 1800 C. The
particles will weld to their next neighbors and you'll end up with a solid
body (it will probably crack because of residual stresses) where the
original particles disappeared. The sintering took place by forming
eutectoids at the interfaces between particles of different composition.
Such eutectoids may melt at temperatures much lower than those of the pure
oxides, greatly increasing the speed of the diffusion processes that cause
sintering.

All the best,

Jacob

At 1:01 12/11/1, bahman elyasi wrote:
>Hi friends:
>
>who knows what is the sintering temperature of CeO2 (ceria) ?
>
>Thanks
>
>
>
>
>
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Prof. Jacob Zabicky
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