Table Of Contenteditor
Kwang-Leong Choy
Imperial College, UK
Innovative Processing of
Films and Nanocrystalline
Powders
Imperial College Press
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INNOVATIVE PROCESSING OF FILMS AND NANOCRYSTALLINE POWDERS
Copyright © 2002 by Imperial College Press
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ISBN 1-86094-316-0
PREFACE
The processing and coating industries manufacturing advanced engineering ceramic
films and powders are under increasing pressure to achieve lower processing costs,
improved efficiency in production, better performance, and less pollution and this
has provided an incentive and driving force for scientists and engineers all over the
world to improve the present processes and develop novel methods. Their common
goals are to lower processing costs and to manufacture new materials in a way
which cannot be achieved by conventional methods. Information on newly
developed processing methods is limited and difficult to obtain because it is
scattered over the various research disciplines involved and so it is time to introduce
a book to draw the information together and to review the latest research into these
methods.
This book is based on a two-day international conference on "Innovative/Cost-
Effective Materials Processing Methods" which was held at Imperial College on 6-7
July, 2000. The aim of the conference was to bring together international engineers
and materials scientists to give technical presentations on the emerging innovative
and cost-effective processing methods which are either in production or at the
research and development stage. These methods are concerned with the fabrication
of films and powders for structural and functional applications. The contributing
authors have been chosen for their pioneering research on the innovative processing
of films and powders and the methods described here have the potential to
revolutionise materials fabrication by providing alternative cost-effective processing
methods to increase both production efficiency and product performance.
The process principles and equipment used for each new method will be
presented and in some cases examples of process modelling and advanced on-line
in-situ process monitoring techniques will be included to help in understanding the
process described. The issues and strategies associated with the scaling-up of the
process will be addressed and various structural characterisations will be presented,
together with an evaluation of the properties of a range of the materials concerned.
Finally the correlation of processing, microstructure and properties, and the potential
applications of each new method will be illustrated with specific case studies.
The innovative and cost-effective processing of films and nanocrystalline
powders provides a useful source of reference for both academic and industrial
researchers on the new processing methods which are emerging for the fabrication
VI Innovative Processing of Films and Nanocrystalline Powders
of these materials. In this book, as stated above, it is hoped that the benefits offered
by these techniques will be clearly demonstrated, including their cost-effectiveness,
efficiency of production, and the development of materials with unique
microstructures for improved performance in engineering components for structural
and functional applications. It will thus stimulate scientific and technological interest
and lead to the eventual exploitation and implementation of these techniques in
materials processing. Finally, it is envisaged that these materials processing methods
have the potential to produce new advanced materials with novel microstructures
and functions to meet the demand for the industrial and social requirements of the
21st century.
Kwang-Leong CHOY
CONTENTS
Preface v
List of Contributors vii
Chapter 1 Review of Advances in Processing Methods: Films and
Nanocrystalline Powders 1
Kwang-Leong Choy
Chapter 2 Process Principles and Applications of Novel and Cost-Effective
ESAVD Based Methods 15
Kwang-Leong Choy
1. Background 15
2. Fundamental of ESAVD 16
2.1. Definition 16
2.2. Process Principles 17
2.3. Process Parameters 20
2.4. Electrostatic Atomisation and Spraying 20
2.5. Electrical Field 22
2.6. Thermal Field 23
2.7. Microstructure of ESAVD Deposits 24
2.8. Advantages 29
2.9. Comparison of ESAVD with Other Electrospraying Techniques 30
2.10. Applications 32
3. Case Studies 34
3.1. ESAVD of Thick Films 34
3.2. ESAVD of Thin Films 42
3.3. Other Variants of ESAVD 53
4. Conclusions and Outlook 66
Acknowledgements 66
References 66
x Innovative Processing of Films and Nanocrystalline Powders
Chapter 3 Application of Pulsed Injection MOCVD to the Deposition of Oxide
Single Layers and Superlattices 71
Jean-Pierre Senateur, Catherine Dubourdieu, V. Galindo, Francois Weiss and
Adolf as Abrutis
1. Introduction 71
2. Deposition of Oxide Films from the Metal-Organic Vapour Phase 75
3. Experimental Set-up and Characterisation 81
4. Results 81
4.1. Oxide Films Grown by Pulsed Injection CVD 81
4.2. Oxide Multilayered Structures Deposited by Pulsed Injection CVD.. 97
5. Conclusions 101
References 102
Chapter 4 Novel Synthesis Nanocrystalline Diamond Films 107
Stanislaw Mitura
1. Introduction 107
2. Experimental 110
2.1. Nucleation of Diamond Particles Ill
2.2. Synthesis of Nanocrystalline Diamond Coatings 117
3. Characterisation 119
3.1. Structural Investigations 119
3.2. Characterisation of the Raman Spectra 120
3.3. AES and Micro X-ray Investigations of Substrate/Film Interface .... 121
3.4. Tribological Investigations 127
3.5. Corrosion Resistance 127
4. Medical Applications 128
4.1. Pre-clinic Investigation 130
4.2. Examples in Medicine 133
5. Mechanical Applications 136
6. Applications in Jewellery 139
7. Conclusions 141
References 142
Acknowledgements 142
Contents xi
Chapter 5 CCVD:Low-Cost Vapour Deposition of Thin Films in the Open
Atmosphere 147
Andrew T. Hunt
1. Introduction to the Combustion CVD Process 145
2. Case Studies 150
2.1. Capacitor Coatings 150
2.2. Coating Conformality 151
2.3. Epitaxial Coatings 152
2.4. Frequency agile thin films for wireless communications 153
2.5. Protective Coatings for Ceramic Matrix Composites and
Corrosion Resistance 154
2.6. Resistor Coatings 157
2.7. Flame Characterization 158
2.8. Fuel Cell Applications 159
3. Summary, Conclusion, and Future Directions 161
References 161
Chapter 6 Hypersonic Plasma Particle Deposition of Nanocrystalline
Coatings 165
S. L. Girshick, J. V. R. Heberlein, P. H. McMurry, W. W. Gerberich, D. I.
lordanoglou, N. P. Rao, A. Gidwani, N. Tymiak, F. Di Fonzo, M. H. Fan, and
D. Neumann
1. Introduction 165
2. Experimental Apparatus 166
3. Particle Synthesis 168
3.1. Thermal Plasma Synthesis 168
3.2. Particle Synthesis with a Thermal Plasma Expanded Through
a Subsonic Nozzle 168
4. Rationale for Operating in the Hypersonic Flow Regime 171
5. Particle Synthesis with a Supersonically Expanded Plasma 172
6. Film Deposition 174
6.1. Apparatus and Operating Conditions 174
6.2. Numerical Modelling of Flow and Particle Trajectories 174
6.3. Experimental Results 178
7. Film Post-Treatment 182
8. Focused Nanoparticle Beam Deposition of Patterned Microstructures 184
9. Summary and Conclusions 188
xi i Innovative Processing of Films and Noncrystalline Powders
Acknowledgments 188
References 189
Chapter 7 Aerosol-Based Flame Synthesis: A Microreactor for Silica
Nanoparticle 193
Karsten Wegner and Sotiris E. Pratsinis
1. Introduction 193
2. Experimental 197
3. Results and Discussion 201
3.1. Jet Mixing 201
3.2. Flame Characterization 203
3.3. Nanoparticle Synthesis 207
4. Conclusions 215
Acknowledgments 216
References 216
Chapter 8 Synthesis of Nanopowders by the Microwave Plasma Process-Basic
Considerations and Perspectives for Scaling-Up 219
Dieter Vollath and D. Vinga Szabo
1. Introduction 219
2. The Microwave Plasma Process 221
2.1. Basic Considerations 221
2.2. The Experimental Set-Up 225
3. Morphology of the Products 228
3.1. Single Phase Ceramic Nanopowders 228
3.2. Ceramic Coated Nanoparticles-Ceramic-Ceramic Nanocomposites.. 233
3.3. Polymer Coated Nanoparticles-Polymer-Ceramic Nanocomposites.. 236
4. Scale Up of the Equipment for Synthesis 237
5. Application of Nanomaterials 242
5.1. Diffusion Barrier Against Grain Growth during Sintering 242
5.2. Modification of the Chemical Surface Properties 242
5.3. Modification of the Physical Properties 243
6. Conclusions 248
References 249
Contents xiii
Chapter 9 Deposition of Electron Beam Evaporant in a Low Vacuum Gas
Flow Environment 253
J.F. Groves and H.N.G. Wadley
1. Motivating Development of a New Vapor Deposition Technology 253
2. Depositing Electron Beam Evaporant from a Gas Flow 254
2.1. Vapor Creation Using an Electron Beam 255
2.2. Vapor Transport in a Flowing Gas Stream 257
2.3. Directed Vapour Deposition 258
3. Experimental Study of "Directed Vapour Deposition" 259
3.1. Gas Flow Fundamentals 260
3.2. Visualizing the Carrier Gas Flow 262
3.3. Visualising the Interaction between Carrier Gas and Vapour Flows .. 263
3.4. Deposition Efficiency at Constant E-beam Power 266
3.5. Deposition Efficiency Under Constant Gas Flow Conditions 268
4. Model-Based Study of "Directed Vapour Deposition" 269
4.1. Model Description 271
4.2. Simulation of DVD Conditions 272
5. Application of DVD to the Creation of Thermal Barrier Coatings 275
6. Enhancing "Directed Vapour Deposition" 277
7. Initial Results from a Second Generation of "Directed Vapour Deposition" ... 280
8. Conclusions 282
Acknowledgments 283
References 283
Index 289
CHAPTER ONE
REVIEW OF ADVANCES IN PROCESSING METHODS:
FILMS AND NANOCRYSTALLINE POWDERS
K. L. Choy
Department of Materials, Imperial College of Science, Technology and Medicine,
Prince Consort Road, London SW7 2BP, UK
There is a rapid growth in the use of advanced engineering ceramic films and
powders for structural and functional applications. The processing and coating
industries manufacturing these engineering materials are under immense pressure to
fulfil the targets of reducing processing costs and increasing production efficiency
while achieving better product performance with lower associated pollution. Such
demand has been brought about by the increased competitiveness of the processing
industries in the global market which has prompted extensive research and
development programmes around the world to develop innovative processing
methods, which will be more cost-effective than conventional techniques.
The book highlights some of the innovative and cost-effective materials
processing techniques relevant to the surface engineering and powder processing
communities in particular. Their potential impact on cost-effectiveness, production
efficiency and the generation of novel microstructures is also presented. This book
is based on a two-day international conference on "Innovative/Cost-Effective
Materials Processing Methods" which was held at Imperial College on 6-7 July
2000. The aim of the conference was to bring together international engineers and
materials scientists to give reviews on the emerging innovative and cost-effective
processing methods which are either already in production or at the research and
development stage.
In order to appreciate the urgent need for new and econonmic materials
processing methods, let us take a step back to look at the various conventional
methods of producing coatings and powders, together with a summary of their
advantages, limitations and their technological niche markets. These methods
include solid state, wet chemical, liquid phase/molten state and vapour processing
