Nanothermites

The recent introduction of the ?nano? dimension to pyrotechnics has made it possible to develop a new family of highly reactive substances: nanothermites. These have a chemical composition that is comparable to that of thermites at submillimeter or micrometric granulometry, but with a morphology having a much increased degree of homogeneity.  This book discusses the methods of preparation of these energetic nanomaterials, their specific properties, and the different safety aspects inherent in their manipulation.

Introduction ix

Chapter 1. Elaboration of Nanoparticles  1

1.1. Solid-phase elaboration  2

1.1.1. Mechanical milling  2

1.2. Liquid-phase elaboration 19

1.2.1. Sonochemistry 19

1.2.2. Microemulsion synthesis  23

1.2.3. Solvothermal syntheses 28

1.2.4. Sol-gel syntheses 39

1.3. Gas-phase elaboration 43

1.3.1. Condensation in inert gas  43

1.3.2. Explosion of metal wires  46

1.3.3. Thermal plasma synthesis  48

1.3.4. Laser ablation 60

1.3.5. Pyrotechnic synthesis  73

Chapter 2. Methods for Preparing Nanothermites  87

2.1. Introduction 87

2.2. Physical mixing  89

2.2.1. Mixing in hexane 89

2.2.2. Mixing in isopropanol  92

2.2.3. Mixing in water  95

2.2.4. Mixing in other solvents 96

2.2.5. Dry mixing 97

2.2.6. Aerosol synthesis of the “building blocks” for physical mixing  98

2.3. Coating 100

2.3.1. Coating oxide with fuel 101

2.3.2. Coating fuel with oxide 102

2.3.3. Coating of fuel with a metal layer 104

2.4. Sol-gel method 104

2.4.1. Formation of oxide around the metal particles  105

2.4.2. Preparation of oxides subsequently mixed with metal 108

2.5. Impregnating porous solids 111

2.6. Assembly  114

2.6.1. Chemical methods  114

2.6.2. Biological methods  117

2.6.3. Electrical methods  118

2.7. Structuring at the surface of substrates 121

2.8. Conclusions and perspectives  125

Chapter 3. The Experimental Study of Nanothermites 127

3.1. Introduction 127

3.2. Study and properties of main fuels 128

3.2.1. Nanometric aluminum  129

3.2.2. Other fuels of interest  157

3.3. Oxidizers of interest for nanothermites  166

3.3.1. Metal or metalloid oxides  167

3.3.2. Oxidizing salts  189

3.4. Methods for the characterization of nanothermites  195

3.4.1. Reactive characterization  196

3.4.2. Morphological characterizations  219

3.5. Conclusion: performance of nanothermites and their enhancement  225

Chapter 4. Nanothermites and Safety  229

4.1. Introduction 229

4.2. Pyrotechnic safety 229

4.2.1. Definition and measurement of sensitivity  230

4.2.2. Techniques used for the desensitization of nanothermites 232

4.2.3. Pyrotechnic risk assessment 236

4.2.4. Regulatory aspects  239

4.3. Neutralization of nanothermites 239

4.4. Toxicological risk 243

4.4.1. Toxicity of the constituents and reaction products of nanothermites  244

4.4.2. Analyses of specific risks and good practices  250

4.5. Conclusions and perspectives  257

Conclusion 259

Bibliography  263

Index 323

Eric Lafontaine is in charge of the scientific field at the Direction générale de l'armement (French Government Defense procurement and technology agency). He specializes in the property structure relationships of materials.

Marc Comet is a researcher at Laboratoire NS3E (ISL - CNRS - University of Strasbourg) in France. His achievements include many publications, patents and international distinctions in the field of nanothermites and energetic nanomaterials.