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