Cold Spray Technology (eBook)

Front Cover 1
Title Page 4
Copyright Page 5
Table of Contents 6
Preface 11
Chapter 1 Discovery of the Cold Spray Phenomenon and its Basic Features 14
1.1 Supersonic Two-phase Flow around Bodies and Discovery of the Cold Spray Phenomenon 15
1.1.1 Experimental setup and research techniques 15
1.1.2 Structure of disturbances induced by reflected particles 16
1.1.3 Interaction of a supersonic two-phase flow with the surface. Effect of coating formation 23
1.2 Spraying with a Jet Incoming onto a Target 26
1.2.1 Acceleration of particles in cold spray 27
1.2.1.1 Diagnostic methods 28
1.2.1.2 Experimental measurement of particle velocity 31
1.2.2 Description of the setup 34
1.2.3 Interaction of individual particles with the surface 35
1.2.4 Transition from erosion to coating formation process. Critical velocity 37
1.2.5 Effect of jet temperature on the deposition efficiency 38
Symbol List 42
References 44
Chapter 2 High-velocity Interaction of Particles with the Substrate. Experiment and Modeling 46
2.1 Deformation of Microparticles in a High-velocity Impact 46
2.1.1 Experimental setup and materials 47
2.1.2 Measurement technique 48
2.1.3 Statistical processing 50
2.1.4 Results of microscopic studies 51
2.1.5 Dependence of strain on impact velocity 52
2.2 Spraying of the Initial Layer and its Influence on the Coating Formation Process 53
2.2.1 Activation of the surface by the particles. Induction time. 54
2.2.2 Critical parameters 58
2.2.3 Determination of the mass of the first coating layer 59
2.2.4 Steady stage of coating formation 60
2.2.5 Kinetics of coating-mass growth 61
2.2.6 Deposition efficiency 62
2.2.7 Correction to the deposition efficiency 65
2.3 Modeling of Interaction of Single Particles with the Substrate within the Framework of Mechanics of Continuous Media 66
2.3.1 Impact of a spherical particle on a rigid substrate 67
2.3.1.1 Impact of elastic particles 67
2.3.1.2 Elastoplastic impact 68
2.3.2 Impact of microparticles on deformable substrates 73
2.4 Formation of a Layer of a High-velocity Flow in the Vicinity of the Microparticle–Solid Substrate Contact Plane 76
2.4.1 Background 77
2.4.2 Modeling of the high-velocity flow layer 79
2.5 Particle–Substrate Adhesive Interaction under an Impact 82
2.5.1 Estimates of the contact time and particle strain in a high-velocity impact 83
2.5.2 Temperature of the particle–substrate contact area in a high-velocity impact 84
2.5.2.1 Analytical modeling 84
2.5.2.2 Results 87
2.5.2.3 Numerical estimates 89
2.5.3 Specific features of adhesive interaction of a non-melted particle with the substrate 89
2.5.3.1 Governing equation for the number of bonds formed 90
2.5.3.2 Heated volume 92
2.5.3.3 Critical velocities 92
2.5.3.4 Diagram of thermal states 93
2.5.3.5 Volume of the material at the melting point 94
2.5.3.6 Contact temperature 94
2.5.3.7 Activation energy 95
2.5.3.8 Adhesion energy 96
2.5.3.9 Elastic energy 97
2.5.3.10 Comparison of energies 98
2.5.3.11 Adhesion probability 99
2.5.3.12 Optimization problem 101
2.5.3.13 Polydispersity 101
2.5.4 Effect of surface activation on the cold spray process 103
2.5.4.1 Activation energy 103
2.5.4.2 Numerical experiment 104
2.5.4.3 Modeling results 105
2.5.4.4 Dependence of the coated area on the particle velocity 106
2.5.4.5 Dependence of the coated area on the particle temperature 109
2.6 Numerical Simulation of Self-organization Processes During the Particle–Surface Impact by the Molecular Dynamics Method 110
2.6.1 Impact of a spherical copper cluster on a rigid substrate 110
2.6.2 Melting at the contact plane in an impact of a nickel cluster on a rigid wall 118
2.6.2.1 Melting of spherical clusters 119
2.6.2.2 Analysis in the near-contact region of the cluster–rigid wall impact 121
Symbol List 124
References 128
Chatper 3 Gas-dynamics of Cold Spray 132
3.1 Flow in a Supersonic Nozzle with a Large Aspect Ratio and a Rectangular Cross Section 134
3.1.1 Experimental determination of gas-flow parameters at the exit of a plane supersonic nozzle 134
3.1.1.1 Experimental setup 134
3.1.1.2 Analysis of experimental results 136
3.1.2 Calculation of gas parameters inside the nozzle 138
3.1.2.1 Allowance for the displacing action of the boundary layer 138
3.1.2.2 Calculation of flow parameters averaged over the cross section 141
3.2 Investigation of Supersonic Air Jets Exhausting from a Nozzle 145
3.2.1 Experimental setup and research techniques 145
3.2.2 Profiles of parameters in jets 146
3.2.2.1 Mach number profiles 146
3.2.2.2 Profiles of excess temperature 147
3.2.3 Streamwise distribution of axial parameters 148
3.2.4 Jet thickness 150
3.2.5 Effect of the jet-pressure ratio 151
3.3 Impact of a Supersonic Jet on a Substrate 153
3.3.1 Pressure distribution on the substrate surface and velocity gradient at the stagnation point 154
3.3.1.1 Velocity gradient at the stagnation point 155
3.3.1.2 Comparison of pressure distributions in the jet and on the substrate surface 156
3.3.2 Effect of the distance from the nozzle exit to the substrate on jet parameters. Oscillations of the jet 157
3.3.3 Near-wall jet 159
3.3.4 Thickness of the compressed layer 162
3.4 Heat Transfer Between a Supersonic Plane Jet and a Substrate Under Conditions of Cold Spray 165
3.4.1 Method for measuring the heat-transfer coefficient 166
3.4.2 Heat-transfer coefficient 168
3.4.3 Temperature of the substrate surface 172
3.5 Optimization of Geometric Parameters of the Nozzle for Obtaining the Maximum Impact Velocity 174
3.5.1 Pattern of gas and particle motion 175
3.5.2 Model for calculating gas and particle parameters 176
3.5.3 Computer application 177
3.5.4 Determination of impact temperature of particles 182
3.5.5 Optimization of nozzle parameters in terms of the impact velocity of particles 183
Symbol List 186
References 188
Chapter 4 Cold Spray Equipments and Technologies 192
4.1 Equipment and Technologies Developed by ITAM SB RAS (Russia) 192
4.1.1 Development of the main elements of the equipment 192
4.1.1.1 Nozzle unit 193
4.1.1.2 Powder feeder 196
4.1.1.3 Gas heater 198
4.1.2 Facilities for applying corrosion-resistant coatings onto pipes 205
4.1.2.1 Facility for applying corrosion-resistant coatings onto the outer surface of long pipes 205
4.1.2.2 Facility for applying corrosion-resistant coatings onto the inner surface of long pipes 208
4.1.3 Portable setup for cold spraying 211
4.1.4 Technologies 214
4.1.4.1 Electro-conductive corrosion-resistant coatings onto electro-technical part 214
4.1.4.2 Metal–polymer coatings and their properties 217
4.2 Eqiupment and Technologies Developed by Ktech Corporation (USA) 229
4.2.1 Equipment and performance data 229
4.2.1.1 System layout 229
4.2.1.2 Pre-chamber and supersonic nozzle assembly 230
4.2.1.3 Gas heater 231
4.2.1.4 Gas control module 233
4.2.1.5 Laboratory powder feeder 234
4.2.1.6 Process control and data acquisition system 235
4.2.2 Spray forming titanium alloys 236
4.2.2.1 Experimental setup 237
4.2.2.2 Powder materials 237
4.2.2.3 Parameter development tests with helium 238
4.2.2.4 Spray forming tests 242
4.2.2.5 Material property results 243
4.2.2.6 Spray formed shapes 246
4.3 Cold Spray System Kinetic 3000 Developed by Cold Gas Technology (Germany) 247
4.3.1 Brief description of equipment 247
4.3.1.1 Control unit 247
4.3.1.2 LINSPRAY® gas heater 249
4.3.1.3 Powder gun 250
4.3.1.4 Powder feeder 251
4.4 Low Pressure Portable Cold Spray System 251
4.4.1 Process history 252
4.4.2 Description of portable equipment 253
Symbol List 256
References 258
Chapter 5 Current Status of the Cold Spray Process 261
5.1 Gas-dynamics of Cold Spray 261
5.2 Interaction of High-speed Particles with the Substrate. Bonding Mechanism 273
5.3 Cold Spray Technologies and Applications 297
5.3.1 Aluminum-containing coatings 297
5.3.2 Copper-containing coatings 299
5.3.3 Nickel-containing coatings 306
5.3.4 Zinc-containing coatings 312
5.3.5 Titanium-containing coatings 314
5.3.6 Coatings with brittle components 317
References 323
Index 337