Interest in studying the combustion of metal powders dramatically raised since Russian scientists Kondratyuk and Tsander suggested the use of metals as energetic additives to rocket fuels at the beginning of the twentieth century. Since that time, it is obvious that an increase in the dispersion of flammable substances participating in heterogeneous combustion processes leads to an increase in rate and heat of combustion. The major energy contribution belongs to the process of oxidation, which is also bound up with powder dispersion and purity. Burning of metal nanopowders is accompanied by new physical and chemical laws (such as high reactivity under heating, threshold phenomena, formation of nitrides in air), which allow to fully appreciate the advantages and disadvantages of nanopowders when used in fuel systems.
Widespread use of metal nanopowders is currently hampered by the lack of enough advanced technology for their preparation, certification, and standardization procedures, instability during storage, and subjective factors: the possible toxicity of nanopowders, investment risks, cost of nanotechnologies, and so on. Therefore, the main objective for the authors is to inform a wide readership of fundamental and applied studies on the processes of oxidation and combustion of metal nanopowders.

Foreword XIII

List of Contributors XV

Introduction XIX

1 Estimation of Thermodynamic Data of Metallic Nanoparticles Based on Bulk Values 1

Dieter Vollath and Franz Dieter Fischer

1.1 Introduction 1

1.2 Thermodynamic Background 2

1.3 Size-Dependent Materials Data of Nanoparticles 4

1.4 Comparison of Experimental and Calculated Melting Temperatures 8

1.5 Comparison with Data for the Entropy of Melting 16

1.6 Discussion of the Results 17

1.7 Conclusions 19

1.A Appendix: Zeros and Extrema of the Free Enthalpy of Melting Gm-nano 20

References 21

2 Numerical Simulation of Individual Metallic Nanoparticles 25

D.S. Wen and P.X. Song

2.1 Introduction 25

2.2 Molecular Dynamics Simulation 27

      2.2.1 Motion of Atoms 27

      2.2.2 Temperature and Potential Energy 28

      2.2.3 Ensembles 29

      2.2.4 Energy Minimization 30

      2.2.5 Force Field 30

      2.2.6 Potential Truncation and Neighbor List 31

      2.2.7 Simulation Program and Platform 32

2.3 Size-Dependent Properties 33

      2.3.1 Introduction 33

      2.3.2 Simulation Setting 34

      2.3.3 Size-Dependent Melting Phenomenon 35

2.4 Sintering Study of Two Nanoparticles 38

      2.4.1 Introduction 38

      2.4.2 Simulation Setting 40

      2.4.3 Sintering Process Characterization 40

2.5 Oxidation of Nanoparticles in the Presence of Oxygen 45

      2.5.1 Introduction 45

      2.5.2 Simulation Setting 47

      2.5.3 Characterization of the Oxidation Process 48

2.6 Heating and Cooling of a Core–Shell Structured Particle 54

      2.6.1 Simulation Method 54

      2.6.2 Heating Simulation 56

      2.6.2.1 Solidification Simulation 59

2.7 Chapter Summary 61

References 63

3 Electroexplosive Nanometals 67

Olga Nazarenko, Alexander Gromov, Alexander Il’in, Julia Pautova, and Dmitry Tikhonov

3.1 Introduction 67

3.2 Electrical Explosion of Wires Technology for Nanometals Production 67

      3.2.1 The Physics of the Process of Electrical Explosion of Wires 68

      3.2.2 Nonequilibrium State of EEW Products – Nanometals 70

      3.2.3 The Equipment Design for nMe Production by Electrical Explosion of Wires Method 71

      3.2.4 Comparative Characteristics of the Technology of Electrical Explosion of Wires 73

      3.2.5 The Methods for the Regulation of the Properties of Nanometals Produced by Electrical Explosion of Wires 74

3.3 Conclusion 75

Acknowledgments 75

References 76

4 Metal Nanopowders Production 79

M. Lerner, A. Vorozhtsov, Sh. Guseinov, and P. Storozhenko

4.1 Introduction 79

4.2 EEW Method of Nanopowder Production 81

      4.2.1 Electrical Explosion of Wires Phenomenon 81

      4.2.2 Nanopowder Production Equipment 84

4.3 Recondensation NP-Producing Methods: Plasma-Based Technology 85

      4.3.1 Fundamentals of Plasma-Chemical NP Production 89

      4.3.2 Vortex-Stabilized Plasma Reactor 90

      4.3.3 Starting Material Metering Device (Dispenser) 92

      4.3.4 Disperse Material Trapping Devices (Cyclone Collectors and Filters) 93

      4.3.5 NP Encapsulation Unit 94

4.4 Characteristics of Al Nanopowders 95

4.5 Nanopowder Chemical Passivation 97

4.6 Microencapsulation of Al Nanoparticles 99

4.7 The Process of Producing Nanopowders of Aluminum by Plasma-Based Technology 102

      4.7.1 Production of Aluminum Nanopowder 102

      4.7.2 Some Properties of Produced Nanopowders of Aluminum, Boron, Aluminum Boride, and Silicon 103

References 104

5 Characterization of Metallic Nanoparticle Agglomerates 107

Alfred P. Weber

5.1 Introduction 107

5.2 Description of the Structure of Nanoparticle Agglomerates 108

5.3 Experimental Techniques to Characterize the Agglomerate Structure 112

      5.3.1 TEM and 3-D TEM Tomography 113

      5.3.2 Scattering Techniques 115

      5.3.3 Direct Determination of Agglomerate Mass and Size 117

5.4 Mechanical Stability 120

5.5 Thermal Stability 124

5.6 Rate-Limiting Steps: Gas Transport versus Reaction Velocity 126

5.7 Conclusions 127

Acknowledgments 128

References 128

6 Passivation of Metal Nanopowders 133

Alexander Gromov, Alexander Il’in, Ulrich Teipel, and Julia Pautova

6.1 Introduction 133

6.2 Theoretical and Experimental Background 136

      6.2.1 Chemical and Physical Processes in Aluminum Nanoparticles during Their Passivation by Slow Oxidation under Atmosphere (Ar + Air) 136

      6.2.2 Chemical Mechanism of Aluminum Nanopowder Passivation by Slow Air Oxidation 140

6.3 Characteristics of the Passivated Particles 143

      6.3.1 Characteristics of Aluminum Nanopowders, Passivated by Gaseous and Solid Reagents (Samples No 1–6, Table 6.7) 148

      6.3.2 Characteristics of Aluminum Nanopowders, Passivated by Gaseous and Solid Reagents (Samples No 7–11, Table 6.7) 149

6.4 Conclusion 150

Acknowledgments 150

References 150

7 Safety Aspects of Metal Nanopowders 153

M. Lerner, A. Vorozhtsov, and N. Eisenreich

7.1 Introduction 153

7.2 Some Basic Phenomena of Oxidation of Nanometal Particles in Air 154

7.3 Determination of Fire Hazards of Nanopowders 155

7.4 Sensitivity against Electrostatic Discharge 158

7.5 Ranking of Nanopowders According to Hazard Classification 159

7.6 Demands for Packing 160

References 161

8 Reaction of Aluminum Powders with Liquid Water and Steam 163

Larichev Mikhail Nikolaevich

8.1 Introduction 163

8.2 Experimental Technique for Studying Reaction Al Powders with Liquid and Gaseous Water 166

      8.2.1 Oxidation of Aluminum Powder with Distilled Water 168

8.3 Oxidation of Aluminum Powder in Water Vapor Flow 174

8.4 Nanopowders Passivated with Coatings on the Base of Aluminum Carbide 175

8.5 Study of Al Powder/H2O Slurry Samples Heated Linear in "Open System" by STA 183

8.6 Ultrasound (US) and Chemical Activation of Metal Aluminum Oxidation in Liquid Water 184

8.7 Conclusion 194

Acknowledgments 195

References 195

9 Nanosized Cobalt Catalysts for Hydrogen Storage Systems Based on Ammonia Borane and Sodium Borohydride 199

Valentina I. Simagina, Oksana V. Komova, and Olga V. Netskina

9.1 Introduction 199

      9.1.1 Experimental 200

      9.1.2 Study of the Activity of Nanosized Cobalt Boride Catalysts Forming in the Reaction Medium of Sodium Borohydride and Ammonia Borane 202

9.2 A Study of Nanosized Cobalt Borides by Physicochemical Methods 204

      9.2.1 A Study of the Crystallization of Amorphous Cobalt Borides Forming in the Medium of Sodium Borohydride and Ammonia Borane 208

      9.2.2 The Effect of the Reaction Medium on the State of Cobalt Boride Catalysts 214

9.3 Conclusions 223

Acknowledgments 224

References 224

10 Reactive and Metastable Nanomaterials Prepared by Mechanical Milling 227

Edward L. Dreizin and Mirko Schoenitz

10.1 Introduction 227

10.2 Mechanical Milling Equipment 228

10.3 Process Parameters 229

10.4 Material Characterization 232

10.5 Ignition and Combustion Experiments 233

10.6 Starting Materials 235

10.7 Mechanically Alloyed and Metal–Metal Composite Powders 236

      10.7.1 Preparation and Characterization 236

      10.7.2 Thermal Analysis 242

      10.7.3 Heated Filament Ignition 245

      10.7.4 Constant Volume Explosion 249

      10.7.5 Lifted Laminar Flame (LLF) Experiments 250

10.8 Reactive Nanocomposite Powders 254

      10.8.1 Preparation and Characterization 256

      10.8.2 Thermally Activated Reactions and their Mechanisms 257

      10.8.3 Ignition 263

      10.8.4 Particle Combustion Dynamics 267

      10.8.5 Constant Volume Explosion 268

      10.8.6 Consolidated Samples: Mechanical and Reactive Properties 271

10.9 Conclusions 273

References 274

11 Characterizing Metal Particle Combustion In Situ: Non-equilibrium Diagnostics 279

Michelle Pantoya, Keerti Kappagantula, and Cory Farley

11.1 Introduction 279

11.2 Ignition and Combustion of Solid Materials 281

      11.2.1 Ignition 281

      11.2.2 Propagation 282

      11.2.3 Flame Speeds 286

11.3 Aluminum Reaction Mechanisms 287

11.4 The Flame Tube 289

11.5 Flame Temperature 292

      11.5.1 Background 292

      11.5.2 Radiometer Setup 294

      11.5.3 Infrared Setup 295

      11.5.4 Linking Radiometer and IR Data for a Spatial Distribution of Temperature 295

11.6 Conclusions 297

Acknowledgments 297

References 297

12 Characterization and Combustion of Aluminum Nanopowders in Energetic Systems 301

Luigi T. De Luca, Luciano Galfetti, Filippo Maggi, Giovanni Colombo, Christian Paravan, Alice Reina, Stefano Dossi, Marco Fassina, and Andrea Sossi

12.1 Fuels in Energetic Systems: Introduction and Literature Survey 301

      12.1.1 An Overall Introduction to Energetic Systems 302

      12.1.2 Experimental Investigations on Micro and Nano Energetic Additives 304

      12.1.3 Theoretical/Numerical Investigations on Energetic Additives 305

      12.1.4 Thermites 308

      12.1.4.1 Nanocomposite Thermites 308

      12.1.5 Explosives 311

      12.1.6 A Short Historical Survey of SPLab Contributions 315

      12.1.7 Concluding Remarks on Energetic Additives 319

12.2 Thermochemical Performance of Energetic Additives 319

      12.2.1 Ideal Performance Analysis of Metal Fuels 319

      12.2.2 Solid Propellant Optimal Formulations 320

      12.2.3 Hybrid Rocket Performance Analysis 322

      12.2.4 Oxidizing Species in Hybrid Rocket Nozzles 324

      12.2.5 Active Aluminum Content and Performance Detriment 325

      12.2.6 Two-Phase Losses 326

      12.2.7 Concluding Remarks on Theoretical Performance 329

12.3 Nanosized Powder Characterization 330

      12.3.1 Introduction 330

      12.3.2 Facilities Used for Nanosized Powder Analyses 331

      12.3.3 Tested nAl Powders: Production, Coating, and Properties 331

      12.3.3.1 Production of nAl Particles 331

      12.3.3.2 Coating of nAl Particles 332

      12.3.3.3 Morphology and Internal Structure of nAl Particles 333

      12.3.3.4 BET Area and Aluminum Content of nAl Particles 333

      12.3.4 DSC/TGA Slow Heating Rate Reactivity 337

      12.3.4.1 Nonisothermal Oxidation of 50 nm Powder 338

      12.3.4.2 Nonisothermal Oxidation of 100 nm Powder 339

      12.3.4.3 Passivation/Coating Efficiency 339

      12.3.5 High Heating Rate Reactivity 341

      12.3.5.1 nAl Powder Ignition Experimental Setup 341

      12.3.5.2 nAl Powder Ignition Representative Results 342

      12.3.6 CCP Collection by Strand Burner 344

      12.3.6.1 Condensed Combustion Product Analysis 344

      12.3.7 Concluding Remarks on Powder Characterization 350

12.4 Mechanical and Rheological Behavior with Nanopowders 350

      12.4.1 Solid Propellants and Fuels: Mechanical and Rheological Behavior 350

      12.4.2 Viscoelastic Behavior 352

      12.4.3 Additive Dispersion 354

      12.4.4 Rheology of Suspensions 355

      12.4.5 Aging Effects 359

      12.4.6 Experimental Results: Data Processing and Discussions 360

      12.4.7 Tested Formulations 361

      12.4.8 Uniaxial Tensile Stress–Strain Tests 362

      12.4.9 Dynamic Mechanical Analysis 364

      12.4.10 Rheological Tests 365

      12.4.11 Concluding Remarks 367

12.5 Combustion of Nanopowders in Solid Propellants and Fuels 367

      12.5.1 Solid Rocket Propellants 368

      12.5.1.1 Particle Clustering Phenomena 368

      12.5.1.2 Propellant Volume Microstructure 369

      12.5.1.3 Steady Combustion Mechanisms of AP/HTPB-Based Composite Propellants 370

      12.5.1.4 Transient Combustion Mechanisms 374

      12.5.1.5 Concluding Remarks 379

      12.5.2 Solid Rocket Fuels for Hybrid Propulsion 380

      12.5.2.1 Tested Ingredients and Solid Fuel Formulations 380

      12.5.2.2 Experimental Setup 381

      12.5.2.3 Time-Resolved Regression Rate 383

      12.5.2.4 Ballistic Characterization: Analyses of the Results 386

      12.5.2.5 Concluding Remarks on Solid Fuel Burning 394

      12.5.3 Chapter Summary 395

Nomenclature 396

References 400

Index 411

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