TECNOLOGIA DOS MATERIAIS CERÂMICOS
VI – DRYING
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
PRESSING FILTER
RAW MATERIALS
SLIP CASTING
DRYING
FINISHING
SINTERING
GRANULATION SPRAY DRYING
PRESSING
CLASSIFICATION
WASTE
ADITIVES DOSAGE
GRINDING AND/OR DRY MIX
GRIDING AND/OR WET MIX
ADITIVES
WASTE
PLASTIC FORMING
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
I-WET ROUTE II-DRY ROUTE
http://www.lippert.de
Drying
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Drying
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Drying
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
http://digitalfire.com/4sight/glossary/glossary_firing_shrinkage.html
http://earthwork7.blogspot.pt/2011_09_01_archive.html
Drying: what could go wrong?
Crasks !
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Linear/volumic deformation !
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Drying: what could go wrong?
Warping !
http://www.fireverseceramics.com/clay-memory-and-movement.html
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Drying: what could go wrong?
http://www.ceramicindustry.com/articles/82979-lean-drying
Drying: inside the drying chamber
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
H2O H2O
H2O
H2O
H2O H2O
air in movement
static air with high relative humidity
surface continuous liquid film
Risk of water saturation!
T Tboiling
T Tboiling
Liquid evaporation rate = f( T , liquid surface area)
= 1/f (liquid concentration in air)
Liquid evaporation rate = f( velocity of Q transfer into the system)
f (liquid concentration in air)
Drying
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Critical moisture content (CMC) corresponds to
the termination of shrinkage. Until CMC a
superficial liquid film is distributed uniformly
throughout the volume.
What really happens at this point?
At CMC the superficial liquid film is interrupted!
Liquid evaporation is no more controlled by T
(and liquid film surface area) but by liquid
diffusion from interior towards exterior of
ceramic piece.
Drying
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
(CMC)
(CMC)
A
B
C D
surface continuous liquid film
A B
C D
Drying
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
surface continuous liquid film
A B
C D
air
(CMC)
Drying
surface continuous liquid film
A B
C D
A
B
C D
surface continuous liquid film
(CMC)
(CMC)
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Drying
surface continuous liquid film
A B
C D
(CMC)
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
surface continuous liquid film
Risk of water saturation!
http://www.ceramicindustry.com/articles/82979-lean-drying
Drying: inside the drying chamber
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
H2O H2O
H2O
H2O
H2O H2O
static air with high relative humidity
Drying
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Drying
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Drying
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Sintering
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Sintering
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Sintering
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Sintering
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Sintering
TECNOLOGIA DOS MATERIAIS CERÂMICOS M. Clara Gonçalves 2015
Further reading
Ceramic Processing and Sintering. M. N. Rahaman CRC Press (2003)
Sintering of Ceramics – New Emerging Techniques. Arunachalam
Lakshmanan (Ed.) INTECWEB.ORG (2012)