ceramic powder forming
DESCRIPTION
ceramic powder formingTRANSCRIPT
V.M. Sglavo – CerSciTech - UNITN 2011
pressing! -! granulated powder!
extrusion, injection moulding! -! ceramic paste!
tape casting, slip casting! -! ceramic suspension!
Forming technologies from powders
powder solvent
additives
water, organic solvent
deflocculant, binder,!plasticizer, lubricant
formability
V.M. Sglavo – CerSciTech - UNITN 2011
Granulation
• direct granulation (pellettization)
water jet
granules
powder
Principles of ceramics processing, 2nd ed., J.S. Reed, J. Wiley & sons, 1995!
500 µm
V.M. Sglavo – CerSciTech - UNITN 2011
Introduction to the principles of ceramic forming, J.G. Heinrich, CFI, 2004!
[mm/
h]
V.M. Sglavo – CerSciTech - UNITN 2011
• spray drying
Principles of ceramics processing, 2nd ed., J.S. Reed, J. Wiley & sons, 1995!
V.M. Sglavo – CerSciTech - UNITN 2011
0% binder
ΔT ΔT
1% binder
ΔT ΔT
4% binder
ΔT ΔT
Granules shape
deformability!
V.M. Sglavo – CerSciTech - UNITN 2011
Example: alumina granules
dispersant = citric acid (0.25 wt%) binder = PVA (1 wt%)
counter-current drying air
J. Ceram. Sci. Tech., 02 [02] 75-88 (2011)!
V.M. Sglavo – CerSciTech - UNITN 2011
granule 1 granule 2 granule 3
J. Ceram. Sci. Tech., 02 [02] 75-88 (2011)!
V.M. Sglavo – CerSciTech - UNITN 2011
Pressing
p = 20-100 MPa
ease of filling
filling shoe!
punch!
mould!
Principles of ceramics processing, 2nd ed., J.S. Reed, J. Wiley & sons, 1995!
V.M. Sglavo – CerSciTech - UNITN 2011
Principles of ceramics processing, 2nd ed., J.S. Reed, J. Wiley & sons, 1995!
V.M. Sglavo – CerSciTech - UNITN 2011
additives
granules
Principles of ceramics processing, 2nd ed., J.S. Reed, J. Wiley & sons, 1995!
V.M. Sglavo – CerSciTech - UNITN 2011
duttile!
Pressing & porosity!
Principles of ceramics processing, 2nd ed., J.S. Reed, J. Wiley & sons, 1995! Introduction to the principles of ceramic forming, J.G. Heinrich, CFI, 2004!
V.M. Sglavo – CerSciTech - UNITN 2011
Principles of ceramics processing, 2nd ed., J.S. Reed, J. Wiley & sons, 1995!
V.M. Sglavo – CerSciTech - UNITN 2011
Pressure distribution!
p = 8.83 MPa
p = 200 MPa
pressione (MPa) densità (%)
132
Principles of ceramics processing, 2nd ed., J.S. Reed, J. Wiley & sons, 1995!
without lubricant
Introduction to the principles of ceramic forming, J.G. Heinrich, CFI, 2004!
V.M. Sglavo – CerSciTech - UNITN 2011
density gradients: • absence of lubricant (B, C) • uneven filling (B) • L/D >2 (A, B) • too high compaction
(sping-back) (A, B, C)
D
L
OK
A B C
Principles of ceramics processing, 2nd ed., J.S. Reed, J. Wiley & sons, 1995!
V.M. Sglavo – CerSciTech - UNITN 2011
Isostatic pressing!
é limited pressure gradients!
ê limited geometric shapes!
p ≤ 100 MPa
flexible mould (rubber)
liquid (oil) flexible cylinder (rubber)
Principles of ceramics processing, 2nd ed., J.S. Reed, J. Wiley & sons, 1995!
p ≤ 500 MPa
V.M. Sglavo – CerSciTech - UNITN 2011
dry bag!
Introduction to the principles of ceramic forming, J.G. Heinrich, CFI, 2004!
V.M. Sglavo – CerSciTech - UNITN 2011
wet bag!
Introduction to the principles of ceramic forming, J.G. Heinrich, CFI, 2004!