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Slip casting of whiteware products (3 parameters that need to be…
Slip casting of whiteware products
Stage involved
1) Pouring of slurry/suspension/slip of ceramic body composition into a porous mould
2) Extraction of water into mould through [pores of mould
3) Forming of solid layer on surface of mould
4) Excess slip removed (except solid cast)
Advantages
i) For complex shaped and big products
ii) High reproducibility rate with smooth surface and fine details to original design
iii) Any form of ceramic suspension is possible as long as the suspension is stable chemically with right concentration
Disadvantages
i) Long processing time (depend on thickness and complexity of cast
ii) Need to dry cast and working mould
iii) Requires large working area
iv) Problem relating to preferential alignment when using clay
Involve 30-35% of water
Requires 2
important criterion
1) Slip requires
high solid content with controlled amount of water
with suitable level of viscosity
to enable flowability transportation, casting
The viscosity level is prepared
without sacrificing high solid content
2) Produced cast with good properties such as
dense
, solid with
good green strength
and not easily cracks
3
parameters
that need to be
controlled
slip density (mass/volume)
Viscosity
Thixotropy
The addition of electrolyte
(deflocculant)
will
reduce the viscosity
to a minimum point before increasing the viscosity again
Torsional Vicometer
can measure viscosity
The lower the value, the higher the viscosity
Requirement of
slurry
for slip casting
1) High solid content
2) Suitable slip viscosity
3) Suitable thixotropy
4) Stable and no chemical reaction and particles always in suspension
