Ceramic Processing

227 Pages·1995·12.714 MB·English

by  I. J. McColm (auth.), R. A. Terpstra, P. P. A. C. Pex, A. H. de Vries (eds.)

Ceramic Processing
Ceramic Processing
Edited by
R.A. Terpstra
Manager ofthe Centre for Technical Ceramics
N etherlands Organization for Applied Scientific Research
TNO, Eindhoven, The Netherlands
P.P.A.C. Pex
Pl'oject Manager, Membrane Materials Development
Netherlands Energy Research Foundation
ECN, Petten, The Netherlands
and
A.H. de Vries
Product Manager, Traditional Ceramics
Netherlands Organizationfor Applied Scientific Research
TNO, Eindhoven, The Netherlands
SPRINGER-SCIENCE+BUSINESS MEDIA, B.\I.
First edition 1995
© 1995 Springer-Science+Business Media Dordrecht
Originally published by Chapman & Hali in 1995
Softcover reprint of tbe hardcover Ist edition 1995
Typeset in 10/12 pt Times by Thomson Press (India) Ltd., New Delhi
Printed in Great Britain by St Edmundsbury Press, Bury St Edmunds
ISBN 978-94-010-4236-9 ISBN 978-94-011-0531-6 (eBook)
DOI 10.1007/978-94-011-0531-6
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Contents
List of contributors ix
Foreword by R. Metselaar xi
Preface xiii
1 Special ceramics for modern applications: which? why? how? 1
1.1. McColm
1.1 Introduction 1
1.2 Predictions arising from simple considerations of strength 5
1.2.1 Group 1: flawless material 6
1.2.2 Replacement of the surface energy term in
equation (1.7) 7
1.3 Materials predictions based on equation (1.16) 9
1.3.1 The product triangle 10
1.4 Some predictions based on fracture toughness 12
1.5 The size and shape of materials needed for processing 14
1.6 Prediction of limiting particle size arising from mechanical
grinding 16
1.7 Combination of ultrafine ceramic powders and fibres:
ceramic-ceramic composites 21
1.7.1 Composite toughness 23
1.8 Relative costs 26
1.9 Self-propagating high-temperature synthesis (SHS) 27
References 33
2 Laser vapour phase synthesis of ceramic powders 34
R.A. Bauer and J. Schoonman
2.1 Introduction 34
2.1.1 General introduction 34
2.1.2 The use of sensitizers 35
2.2 Experimental aspects 37
2.3 Results 38
2.3.1 Optical absorption measurements 38
2.3.2 Thermodynamic calculations 41
2.3.3 Visible spectroscopy 46
VI Contents
2.3.4 Synthesis of silicon 49
2.3.5 Synthesis of Si3N4 51
2.4 Discussion 54
2.5 Conclusions 55
References 56
3 Particle interactions in suspensions 58
KG. Horn
3.1 Introduction 58
3.2 Surface forces 59
3.2.1 Forces and energies 61
3.2.2 Flat and curved surfaces: the Derjaguin approximation 61
3.2.3 van der Waals forces 63
3.2.4 Electrostatic forces in a non-polar environment 68
3.2.5 Electrostatic forces in a polar liquid: double-layer
repulsion 69
3.2.6 DLVO theory 75
3.2.7 Charge correlation effects 77
3.2.8 Structural forces 78
3.2.9 Solvation forces 79
3.2.10 'Hydrophobic' forces 80
3.2.11 Capillary forces 81
3.2.12 Effects of surfactants 83
3.2.13 Effects of polymers 85
3.2.14 Short-range forces 87
3.2.15 Present status of theoretical and experimental
work on surface forces 88
3.3 Behaviour of suspensions 89
3.3.1 Dispersion 89
3.3.2 Dense suspensions 89
3.3.3 Consolidation 91
3.3.4 Rheology 92
3.3.5 Strength of consolidated body 93
3.4 Controlling interparticle forces 93
3.4.1 Minimizing attractive forces 94
3.4.2 Arranging repulsive forces 94
3.4.3 Other considerations 96
3.5 Some examples 97
3.5.1 Improved strength from homogenization of powder 97
3.5.2 Aggregation with strong attractive forces gives low
volume fraction 97
3.5.3 Adding the right amount of polymer dispersant 98
3.5.4 Effective use of block copolymer 98
3.5.5 Controlling rheology as well as stability 98
Contents Vll
3.5.6 Maintaining low viscosity until after forming 99
3.5.7 Using 'one stone to kill two birds' 99
References 100
4 Dry pressing of ceramic powders 102
D. Bortzmeyer
4.1 Introduction 102
4.2 Industrial problems 103
4.2.1 Compaction technology 103
4.2.2 A few compaction problems 104
4.3 Macroscopic behaviour: the classical approach 107
4.3.1 DensityI pressure relationship: theoretical and
experimental 107
4.3.2 piP relationship: influence of powder characteristics 109
4.3.3 piP relationship: influence of process parameters 115
4.3.4 Radial pressure coefficient 117
4.3.5 Wall friction coefficient 120
4.3.6 Green tensile strength 120
4.3.7 Conclusion 123
4.4 Macroscopic behaviour: the mechanical approach 124
4.4.1 Density distribution measurement 124
4.4.2 Continuum mechanics theory 127
4.4.3 Experimental 128
4.4.4 Results 129
4.4.5 Numerical simulation 131
4.4.6 Conclusion 132
4.5 Microscopic behaviour 133
4.5.1 Microstructure evolution 133
4.5.2 Micromechanics of compaction 135
4.5.3 Conclusion 139
4.6 Conclusions 140
Appendix: Tensor notation for stress 141
References 142
5 The principles of tape casting and tape casting applications 147
R.E. Mistler
5.1 Introduction 147
5.2 The doctor blade tape process 153
5.2.1 Materials technology and seleCtion 153
5.2.2 Tape casting process and equipment 156
5.3 Subsequent processing of unfired tapes 165
5.3.1 Shaping 165
5.3.2 Multilayer processing 166
References 172
Vlll Contents
6 Plastic forming of ceramics: extrusion and injection moulding 174
M.A. Janney
6.1 Introduction to extrusion 174
6.2 Formulation principles 174
6.2.1 Role of additives 175
6.2.2 Powder 178
6.3 Mixing 179
6.4 Soil mechanics 183
6.4.1 Extrusion theory 183
6.4.2 Wet strength 184
6.5 The extrusion process 185
6.5.1 Equipment 185
6.5.2 Mechanics of flow 186
6.5.3 Dies 190
6.5.4 Defects 191
6.6 Additional topics 192
6.6.1 Ultrasonic extrusion 192
6.6.2 Multilayer or coaxial extrusion 194
6.7 Introduction to injection moulding 194
6.7.1 A little history 195
6.7.2 Limitations 195
6.7.3 The process 195
6.8 Detailed discussion of the process 196
6.8.1 Powder considerations 196
6.8.2 Formulation 197
6.8.3 Mixing 199
6.8.4 Equipment 199
6.8.5 Binder removal 201
6.8.6 Moulding parameters 201
6.8.7 Defects 204
6.8.8 Other factors 205
6.9 New approaches to forming complex shapes 206
References 209
Index 213
Contributors
R.A. Bauer, PHD, Department ofInorganic Materials, TNO, Eindhoven, The
Netherlands.
D. Bortzmeyer, PHD, Leader of Shape Forming Group, Rhone-Poulenc
Research, Aubervilliers, France.
R.G.Horn PHD, Professor of Materials Science, University of South Australia,
Adelaide Australia.
M.A. Janney, PHD, Metals and Ceramics Division, Oak Ridge National
Laboratory, Tennessee, USA.
I.J. McColm, DSe, DPHIL, FRSC, C. CHEM., FIM, FRSA, Professor of
Ceramic Materials, Department of Industrial Technology, University of
Bradford, UK.
R.E. Mistler, SeD, Richard E. Mistler Inc., Morrisville, Pennsylvania, USA.
J. Schoon man, MSe PHD, Professor of Applied Inorganic Chemistry, Delft
University of Technology, The Netherlands.
Foreword
Two years after the foundation of the European Ceramic Society the first
ECerS Conference was held in Maastricht, The Netherlands. After this
successful conference it was felt that the ECerS should not only stimulate
ceramic research but also run projects of an educational character. To this end
the Netherlands Ceramic Society decided to sponsor a summerschool on
ceramic processing intended for young ceramists from European countries.
Several internationally recognized ceramic specialists were prepared to lecture
and the course was fully attended. In fact, this course showed that there is
a clear need for dedicated courses at a moderate fee. A venue was chosen where
the participants would have ample opportunities for personal contacts. In this
way the summerschool gave the students more than purely technical training.
After the meeting the ECerS Council established an Educational Committee
to take care of educational matters on a permanent basis. Following an
initiative of the French Ceramic Society a special Conference of Higher
Educational Institutions in Ceramics was organized under the name Euro
forum in 1992 in Limoges, France. The second Euroforum was held in 1994 in
Hohr-Grenzhausen, Germany. These meetings aim to bring together educa
tors, graduates and industrial managers. Further activities under the auspices
of the ECerS are planned.
Having been involved in the preparation of the course, it is a great pleasure
to introduce the book of the proceedings of the NKV-summerschool. The
contents and the level are such that we trust that many ceramists will benefit
from the book.
I congratulate the editors and organizers of the summerschool on their
initiative.
R. Metselaar
Past-president. ECerS
Preface
This book has been edited from the lectures given at the NKV-summerschool
on ceramic processing which was organized by the Netherlands Ceramic
Society (NKV), 5-9 September 1991 in Petten, The Netherlands.
The NKV-summerschool was sponsored by:
• The Netherlands Ceramic Society, NKV
• The European Ceramic Society, ECerS
• Ceramic Manufacturers Association, VKI
• The Netherlands Energy Research Foundation, ECN
• The Netherlands Organisation for Applied Scientific Research, TNO
• The National Ceramic Centre, NKA
• The Centre for Technical Ceramics, CTK
• N.V. Royal Sphinx, Maastricht
• Hoogovens Industrial Ceramics, HIC
• Gimex, Geldermalsen
• NIF A Instruments, Leeuwarden
• CAM Implants, Leiden
• Royal Tichelaar, Makkum
• Ceratec, Haaften
The following people were responsible for organizing the NKV-Summer
school:
• Dr ir R.A. Terpstra, CTK (Chairman)
• Ir P.P.A.C. Pex, ECN (Secretary)
• Mr A.H. de Vries, TNO-Ceramics (Treasurer)
• Prof. dr R. Metselaar, CTK/Eindhoven University ofTechnology (Scientific
Advisor)
• Mrs C.A.L. Ruitenburg, ECN (Local organizer)
• Ing. PJ. van Tilborg, ECN (Local organizer)
The NKV-summerschool was arranged to provide (graduate) students, scien
tists and engineers an opportunity to attend an advanced course in ceramic
processing taught by internationally well-known lecturers.
The lectures were presented by specialists on topics most relevant for
ceramic processing, starting from powder synthesis and the behaviour of
powder particles in dispersions in relation to colloidal consolidation