Foreword	6
	Preface	10
	Contents	12
	About the Authors	28
	Chapter 1: Introduction	30
	1.1 Needs for Coatings	30
	1.2 Thin Films vs. Thick Films	31
	1.3 Thermal Spray Coating Concept	31
	1.4 Description of Different Thermal Spray Coating Processes	33
	1.5 History of Thermal Spray	36
	1.6 Thermal Spray Applications	37
	1.7 Overview of Book Content	42
	References	43
	Chapter 2: Overview of Thermal Spray	45
	2.1 Surface Treatments or Coatings	45
	2.1.1 Why Surface Treatment or Coatings	45
	2.1.2 Surface Treatments	46
	2.1.2.1 Strain Hardening	46
	2.1.2.2 Surface Hardening	46
	2.1.2.3 Thermo Chemical Treatments	46
	2.1.3 Coatings	47
	2.1.3.1 Electro/Electroless Plating	47
	2.1.3.2 Chemical Vapor Deposition	47
	2.1.3.3 Physical Vapor Deposition	48
	2.1.3.4 Pulsed Laser Deposition	50
	2.1.3.5 Thermal Spray	50
	2.2 Brief Descriptions of Thermal Spray Applications	53
	2.3 Overview of Thermal Spray Processes	55
	2.3.1 Compressed Gas Expansion	56
	2.3.2 Combustion Spraying	56
	2.3.3 Electrical Discharge Plasma Spraying	56
	2.4 Substrate Preparation	60
	2.5 Energetic Gas Flow Generation	61
	2.5.1 Cold Spray	61
	2.5.1.1 Conventional High-Pressure Cold Spray	61
	2.5.1.2 Low-Pressure Cold Spray	62
	2.5.2 Flame Spray	63
	2.5.2.1 Powder Flame Spraying	63
	2.5.2.2 Wire, Rod, or Cord Flame Spraying	63
	2.5.3 High-Velocity Oxy-fuel Spraying	64
	2.5.4 Detonation Gun Spraying	66
	2.5.5 Direct Current Blown Arc Spraying or d.c. Plasma Spraying	67
	2.5.6 Vacuum Induction Plasma Spraying	68
	2.5.7 Wire Arc Spraying	70
	2.5.8 Plasma-Transferred Arc Deposition	71
	2.6 Material Injection	72
	2.6.1 Powder Injection	72
	2.6.2 Wire, Rod, or Cord Injection	75
	2.6.3 Liquid Injection	78
	2.6.3.1 Gas Atomization	78
	2.6.3.2 Mechanical Injection	78
	2.7 Energetic Gas-Particle Interactions	79
	2.7.1 Momentum Transfer	79
	2.7.2 Heat Transfer	80
	2.7.3 Effect of the Surrounding Atmosphere	82
	2.7.3.1 Particle In-Flight Oxidation	83
	2.7.3.2 Substrate and Successive Passes	83
	2.7.3.3 Chemical Reactions Other Than Oxidation	84
	2.7.3.4 Limiting Gas-Induced Reactions	84
	2.8 Coating Formation	85
	2.8.1 Coatings from Fully or Partially Melted Particles in Conventional Spraying	85
	2.8.2 Adhesion of Conventional Coatings	88
	2.8.2.1 Hot Particles	88
	2.8.2.2 Cold Particles	90
	2.8.3 Coatings Resulting from Solution or Suspension Spraying	91
	2.8.4 Residual Stresses	92
	2.9 Control of Coating Formation	93
	2.9.1 Coating Temperature Control Before, During, and After Spraying	93
	2.9.2 Control of Other Spray Parameters	95
	2.9.2.1 Surface Preparation	95
	2.9.2.2 Standoff Distance	96
	2.9.2.3 Impact Angle	96
	2.9.2.4 Beads	96
	2.9.2.5 Passes	96
	2.10 Summary and Conclusions	97
	Nomenclature	97
	References	98
	Chapter 3: Fundamentals of Combustion and Thermal Plasma	101
	3.1 Combustion	101
	3.1.1 Definitions	101
	3.1.2 Combustion at Equilibrium	102
	3.1.3 Combustion Kinetics	104
	3.1.3.1 One-Step Reactions	104
	3.1.3.2 Simultaneous Interdependent and Chain Reactions	105
	3.1.3.3 Criterion for Explosion	106
	3.1.4 Combustion or Deflagrations, Detonations	107
	3.1.4.1 Combustion (Deflagration)	107
	3.1.4.2 Detonation	110
	3.2 Thermal Plasmas Used for Spraying	112
	3.2.1 Definition	112
	3.2.2 Plasma Composition	113
	3.2.3 Thermodynamic Properties	116
	3.2.4 Transport Properties	117
	3.2.4.1 Electrical Conductivity	117
	3.2.4.2 Molecular Viscosity	118
	3.2.4.3 Thermal Conductivity	120
	3.3 Basic Concepts in Modeling	123
	3.3.1 Introduction	123
	3.3.2 Conservation Equations	123
	3.3.2.1 Continuity Equations	124
	3.3.2.2 Momentum Equations	126
	3.3.2.3 Energy Equations	127
	3.3.2.4 Electromagnetic Field Equations	128
	3.3.2.5 Laminar or Turbulent Flows	130
	3.3.3 Gas Composition, Thermodynamic, and Transport Properties	132
	3.3.3.1 Gas Composition	132
	3.3.3.2 Thermodynamic Properties	134
	3.3.3.3 Transport Properties	134
	3.4 Summary and Conclusions	134
	Nomenclature	135
	References	138
	Chapter 4: Gas Flow-Particle Interaction	140
	4.1 Introduction	140
	4.2 Single Particle Trajectory	141
	4.2.1 Single Particle Motion	141
	4.2.2 Particle Injection and Trajectory	143
	4.2.2.1 Radial Injection	143
	(a) Influence of the Injection Conditions	144
	(b) Influence of the Injector Acceleration and Inclination	146
	(c) Influence of Other Parameters	147
	(d) Optimization of the Injection	147
	(e) Influence of Plasma Jet Fluctuations	148
	(f) Influence of the Plasma Flow Computational Model	150
	4.2.2.2 Axial Injection	151
	(a) Flame Spraying	151
	(b) HVOF	151
	(c) D-Gun	151
	(d) Plasma Spraying	152
	(e) Cold Spray	154
	4.2.3 Drag Coefficient: Micrometer Sized Single Sphere	155
	4.2.3.1 Calculations Without Any Correction	155
	4.2.3.2 Corrections Due to Various Effects	158
	(a) Influence of the Temperature Gradients	158
	(b) Influence of the non-Continuum Effect	160
	4.2.3.3 Trajectory Corrections Due to Various Effects	161
	(a) Effect of Temperature Gradient	161
	(b) Effect of Rarefaction and Vaporization	162
	(c) Effect of Turbulence	162
	4.2.3.4 Other Effects	163
	(a) Particle Shape	163
	(b) Particle Charging	164
	4.2.4 Drag Coefficient: Submicron and Nanometer-Sized Particles	165
	4.2.4.1 Problem of Particle Inertia	165
	4.2.4.2 Thermophoresis Effect	166
	4.3 In-Flight Single Particle Heat and Mass Transfer and Chemical Reactions	167
	4.3.1 Basic Conduction, Convection, and Radiation Heat Transfers	167
	4.3.2 In-Flight Particle Heating and Melting	169
	4.3.2.1 Basic Assumptions and Governing Equations	169
	4.3.2.2 Example of Results	170
	(a) DC Plasma Jets	170
	(b) RF Inductively Coupled Plasmas	171
	(c) HVOF Spraying	173
	i. Radial Injection	173
	ii. Axial Injection	173
	4.3.3 Heat Transfer to a Single Sphere	175
	4.3.3.1 Influence of Temperature Gradients	175
	4.3.3.2 Influence of non-Continuum Effect	179
	4.3.3.3 Role of Heat Conduction in Fully Dense Particles	180
	(a) Particle Immersed in an Infinite Hot Gas at Constant Temperature	180
	(b) Particles in-Flight	185
	4.3.3.4 Heat Conduction in Porous Particles	187
	4.3.3.5 Vaporization	190
	(a) Heating of the Vapor	193
	(b) Radiation of the Vapor	195
	4.3.3.6 Chemical Reactions with the Vapor	196
	4.3.3.7 Chemical Reactions with the Particle	198
	(a) Diffusion Controlled Reactions	198
	(b) Reactions Taking Place Between Condensed Phases	200
	(c) Reactions Controlled by Convection Within the Liquid Phase	201
	4.4 Ensemble of Particles and High-Energy Jet	203
	4.4.1 General Remarks	203
	4.4.2 Particle Injection	205
	4.4.2.1 Types of Injector	205
	4.4.2.2 Gas Flow Within the Injector	206
	4.4.2.3 Particle Flow at the Injector Exit	207
	(a) Straight Injector	207
	(b) Straight Double-Flow Injector	209
	(c) Curved Injector	211
	4.4.2.4 Interaction Between the Plasma Flow and the Carrier Gas Jet	212
	4.4.2.5 Concluding Remarks About Particle Injection	214
	4.4.3 Particles and Plasma Jet with No Loading Effect	214
	4.4.3.1 Modeling of Interactions with Particles	214
	4.4.3.2 Example of Results	215
	(a) d.c. Plasma Jet	215
	(b) Cold Spray	217
	4.4.4 Loading Effect	218
	4.4.4.1 Modeling	218
	4.4.4.2 Examples of Results	219
	(a) Ar R.F. Induction Plasma with Copper Particles	219
	(b) d.c. Plasma with Alumina Particles	221
	(c) HVOF	221
	(d) Cold Spray	222
	4.5 Liquid or Suspension Injection into a Plasma Flow	222
	4.5.1 Liquid Injection	223
	4.5.1.1 Spray Atomization	223
	4.5.1.2 Mechanical Injection	227
	4.5.2 Liquid Penetration into the Plasma Flow	229
	4.5.3 Liquid Fragmentation	230
	4.5.3.1 Simple Approach	230
	4.5.3.2 More Elaborated Description	232
	4.5.4 In-Flight Heat Transfer to Droplets	234
	4.5.5 Cooling of the Plasma Flow by the Liquid	235
	4.5.6 Influence of Arc Root Fluctuations	236
	4.5.7 Case of No Fragmentation	238
	4.6 Summary and Conclusions	239
	Nomenclature	239
	References	242
	Chapter 5: Combustion Spraying Systems	254
	5.1 Historical Perspective and General Remarks	254
	5.2 Flame Spraying	255
	5.2.1 Principle	255
	5.2.2 Powder Flame Spraying	256
	5.2.2.1 Spray Conditions	256
	5.2.2.2 Materials Used	260
	(a) Metals	260
	(b) Self Fluxing Alloys	260
	(c) Few Ceramic (Oxide) Materials	260
	(d) Reactive Spraying	260
	(e) Polymers	260
	(f) Glass	262
	5.2.3 Liquid Flame Spraying	262
	5.2.4 Wire, Rod, or Cord Spraying	262
	5.2.4.1 Wire	263
	5.2.4.2 Rod and Cord	264
	5.2.5 Flame Modeling	265
	5.3 High Velocity Flame Spraying (HVOF-HVAF)	266
	5.3.1 HVOF or HVAF Powder Spraying	266
	5.3.1.1 HVOF Processes Description	266
	5.3.1.2 HVOF Gas Flow Description	269
	5.3.1.3 Results of HVOF Gas Flow Modeling	269
	5.3.1.4 HVOF Particle Temperatures and Velocities	277
	5.3.1.5 Particle Oxidation	280
	5.3.1.6 HVAF and Modified HVOF Processes	283
	5.3.1.7 Coating Formation	286
	5.3.1.8 Summary of HVOF and HVAF Torch Evolution	287
	5.3.2 HVOF Wire Spraying	287
	5.3.3 Applications: General Remarks	289
	5.3.4 Coatings Sprayed with Combustible Gases and Oxygen	289
	5.3.4.1 Metals	289
	5.3.4.2 Cermets	290
	5.3.4.3 Ceramics	291
	5.3.4.4 Polymers	291
	5.3.5 Coatings Sprayed with Liquid Fuel and Oxygen	292
	5.3.6 HVOF-HVAF Modeling	293
	5.3.6.1 1D Calculations	293
	5.3.6.2 2D Or 3D Calculations	295
	(i) Combustion Calculation	295
	(ii) Flow Calculation	295
	5.4 Detonation Gun (D-Gun)	296
	5.4.1 Process Description	296
	5.4.1.1 (a) First Stage Comprising	297
	5.4.1.2 (b) Second Stage with	298
	5.4.1.3 (c) Third Stage Including	298
	5.4.2 In-Flight Particle Properties	302
	5.4.3 Graded Coatings	305
	5.4.4 Coating Properties	305
	5.4.4.1 Plain Fatigue and Fretting Fatigue	305
	5.4.4.2 Oxidation-Resistant Coatings	306
	5.4.4.3 Thermal Barrier Coatings (TBCs)	307
	(a) TBC´s Bond Coat	307
	(b) TBC´s Ceramic Layer	307
	(c) Graded Coatings	308
	5.4.4.4 Wear-Resistant Coatings	309
	(a) WC-Co	309
	(b) Alumina	311
	(c) Alumina-Titania	312
	(d) Tribological Coatings	312
	(f) Corrosion and Wear-Resistant Coatings	312
	(g) Erosion Resistance	313
	Other Cermets	314
	Alloys	315
	5.4.4.5 D-gun Modeling (1D)	315
	5.5 Summary and Conclusions	317
	Nomenclature	318
	References	319
	Chapter 6: Cold Spray	331
	6.1 Introduction to the Different Cold Spray Processes	331
	6.1.1 High-Pressure Cold Spray	331
	6.1.1.1 Conventional Cold Spray	331
	6.1.1.2 Kinetic Spray Process	333
	6.1.1.3 Pulsed Gas Dynamic Spraying Process	334
	6.1.2 Low Pressure Cold Spray	335
	6.1.3 Vacuum Cold Spray	337
	6.2 High-Pressure Cold Spray Process	338
	6.2.1 Process Gas Dynamics	338
	6.2.1.1 One-Dimensional Geometry and Isentropic Expansion of the Flow	338
	(a) Very Simple Models	338
	(b) More Complex Models	340
	6.2.1.2 Effect of Boundary Layer and the Shock on the Substrate	341
	6.2.1.3 2D and 3D Compressible Models	342
	6.2.1.4 Nozzle Design	351
	6.2.2 Coating Adhesion and Cohesion	352
	6.2.2.1 Deposition of the First Layer	352
	(a) Induction Time	352
	(b) Particle and Substrate Deformation	352
	(c) Phenomena at Impact	354
	(d) Minimum Particle Diameter	355
	(e) Critical Velocity	356
	(f) Empirical Expressions for the Critical Velocity	358
	(g) Material Suitability	360
	(h) Substrate	361
	6.2.2.2 Coating Formation	361
	(a) Basic Phenomena	361
	(b) Deposition Efficiency	365
	6.2.3 Deposition Parameters	368
	6.2.3.1 Spray Conditions	368
	(a) Spray Gases	368
	(b) Nozzle Design	368
	6.2.3.2 Particles	369
	(a) Spray Angle	369
	(b) Influence of Particle Diameter, Specific Mass, and Specific Heat	370
	(c) Particle Temperature	370
	(d) Laser-Assisted Cold Spray	372
	(e) Particle Oxidation	373
	(f) Carrier Gas	373
	(g) Loading Effect	373
	(h) External Parameters	374
	(i) Heat Treatment After Spraying	375
	6.2.3.3 Substrates	375
	6.2.3.4 Composite Materials	376
	(a) Cermets with Tungsten Carbide	377
	(b) Other Cermets	379
	i. Separate Injection	379
	ii. Metal-Ceramic Blends	380
	iii. Particles Made of Metal and Ceramic	381
	(c) Composite Metals	381
	6.3 Coating Materials and Applications	382
	6.3.1 General Remarks	382
	6.3.2 Metals	382
	6.3.2.1 Aluminum	384
	6.3.2.2 Copper	385
	6.3.2.3 Nickel	386
	6.3.2.4 Selective Galvanizing	386
	6.3.2.5 Superalloys	387
	6.3.2.6 Titanium	387
	6.3.2.7 Iron and Steel	388
	6.3.2.8 Tantalum	388
	6.3.2.9 Pure Silicon	389
	6.3.2.10 Pure Silver	389
	6.3.2.11 Metallic Coatings on Polymers	389
	6.3.3 Composites	389
	6.3.3.1 Pure Iron (99.5%) Or Stainless Steel (304L) Reinforced by Diamond	390
	6.3.3.2 Aluminum and Copper	390
	6.3.3.3 Fabrication of Cermet Coatings	391
	6.3.3.4 Fe-Al Intermetallic Compounds	392
	6.3.4 Ceramics	392
	6.4 Low Pressure Cold Spray (LPCS)	395
	6.4.1 Coating Formation	395
	6.4.2 Examples of Coatings	396
	6.5 Summary and Conclusions	398
	Nomenclature	399
	References	400
	Chapter 7: D.C. Plasma Spraying	409
	7.1 Description of Concept	409
	7.2 Equipment and Operating Parameters	412
	7.3 Fundamentals of Plasma Torch Design	414
	7.3.1 Torch Cathode	415
	7.3.2 Arc Column	417
	7.3.3 Torch Anode	419
	7.3.4 Arc Voltage and Power Dissipation	420
	7.3.5 Arc Stability	420
	7.3.6 Electrode Erosion	426
	7.4 Particle Injection	429
	7.5 Plasma Torch and Spray Process Modeling	434
	7.6 Plasma Torch and Jet Characterization: Time Averaged	438
	7.6.1 Effect of Plasma Gas	439
	7.6.2 Effect of Plasma Gas Injector Design	442
	7.6.3 Effect of Anode Nozzle Design	444
	7.6.4 Effect of Surrounding Atmosphere	447
	7.6.5 Effect of Cathode Shape	447
	7.6.6 Effect of Standoff Distance	448
	7.6.7 Summary of Design and Operating Parameters	450
	7.7 Plasma Jet Characterization: Transient Behavior	450
	7.7.1 Plasma Jet Instability	450
	7.7.2 Effect of Arc Voltage Fluctuations on Plasma Jet and Particle Characteristics	453
	7.8 Different Plasma Torch Concepts	459
	7.8.1 Shrouds and Other Fluid Dynamic Jet Stabilization	459
	7.8.2 Fixed Anode Attachment Position	463
	7.8.3 Central Injection Torches	466
	7.8.4 Torches for Inside Diameter Coatings	469
	7.8.5 High-Power Plasma Spray Torch	470
	7.8.6 Water-Stabilized Plasma Torch	470
	7.9 Low Pressure and Controlled Atmosphere Plasma Spraying	472
	7.10 Plasma-Sprayed Materials and Coatings	480
	7.10.1 Oxide Materials	481
	7.10.1.1 Alumina	481
	7.10.1.2 Titania and Alumina-Titania Coatings	483
	7.10.1.3 Chromium Oxide	484
	7.10.1.4 Zirconia	484
	7.10.1.5 Other Oxides	485
	7.10.2 Non-oxide Ceramics	486
	7.10.3 Cermets	488
	7.10.4 Metals or Alloys	489
	7.10.4.1 Vacuum Plasma-Sprayed Metal Coatings	489
	7.10.4.2 Air Plasma-Sprayed Metal Coatings	490
	7.11 Summary and Conclusions	491
	Nomenclature	492
	References	493
	Chapter 8: R.F. Induction Plasma Spraying	504
	8.1 Introduction	504
	8.2 The r.f. Induction Plasma Torch	506
	8.2.1 Basic Concepts	506
	8.2.2 Energy Coupling Mechanism	508
	8.2.2.1 Electromagnetic Coupling and Skin Depth	508
	8.2.2.2 Energy Coupling Efficiency	512
	8.2.2.3 Minimum Sustaining Power	513
	8.2.3 Induction Plasma Torch Design	515
	8.2.3.1 Flow Stabilization Mechanism	515
	8.2.3.2 Segmented Metal Wall Torches	517
	8.2.3.3 Ceramic Wall Torches	517
	8.2.3.4 Hybrid Plasma Torches	519
	8.2.4 Temperature, Fluid Flow, and Concentration Fields	522
	8.2.4.1 Temperature Fields	522
	8.2.4.2 Flow Fields	524
	8.2.4.3 Concentration Fields	528
	8.3 Modeling of the Inductively Coupled Plasma Discharge	534
	8.3.1 Basic Assumption	536
	8.3.2 Governing Equations	536
	8.3.2.1 Continuity Equation	536
	8.3.2.2 Momentum Equations	536
	8.3.2.3 Energy Equation	537
	8.3.2.4 Species Conservation Equations	538
	8.3.2.5 Vector Potential Equations	540
	8.3.2.6 Equations and Boundary Condition for Extended Field Model	543
	8.3.2.7 Turbulence Model	545
	8.3.3 Typical Results of Fluid Dynamic Modeling	546
	8.4 Plasma-Particle Interaction Model	557
	8.4.1 Governing Equations	559
	8.4.1.1 Continuity, Momentum, Energy, and Mass Conservation Equations	559
	8.4.1.2 Particle Trajectory Equations and Plasma-Particle Interactions	560
	8.4.2 Typical Result: Effect of Particle Loading	561
	8.5 Vacuum Induction Plasma Spraying	574
	8.5.1 Basic Equipment Design	574
	8.5.2 Parametric Analysis and Operating Conditions	579
	8.5.3 Reactive Induction Plasma Spraying	587
	8.5.4 Suspension Induction Plasma Spraying	589
	8.5.5 Supersonic Induction Plasma Spraying	592
	8.6 Summary and Conclusions	594
	Nomenclature	594
	References	596
	Chapter 9: Wire Arc Spraying	602
	9.1 Description of Concept	602
	9.2 Equipment and Operating Parameters	604
	9.3 Wire Materials and Specific Applications	607
	9.3.1 Wires	607
	9.3.2 Cored Wires	610
	9.4 Metal Droplet Formation	612
	9.5 Process Characterization	622
	9.5.1 Gas Velocity Measurements	624
	9.5.2 Metal Droplet Velocity Distributions	625
	9.5.3 Metal Droplet Temperature	632
	9.5.4 Coating Characteristics	633
	9.5.5 Fume Formation	637
	9.6 Process Modeling	638
	9.7 Single Wire Arc Spraying	643
	9.8 Special Developments: Low-Pressure Wire Arc and 90 Angle Spraying	647
	9.9 Summary and Conclusions	648
	Nomenclature	649
	References	649
	Chapter 10: Plasma-Transferred Arc	655
	10.1 Description of Concept	655
	10.1.1 Tungsten Inert Gas	657
	10.1.2 Metal Inert Gas	657
	10.2 Equipment and Operating Parameters	658
	10.3 Coating Materials and Applications	663
	10.3.1 Corrosion and Wear	663
	10.3.2 Self-Lubricating Coatings	665
	10.3.3 Rebuilding of Parts	666
	10.3.4 Free-Standing Shapes	666
	10.4 Process Characterization	666
	10.4.1 Temperature Distributions in the Arc and Arc Voltages	667
	10.4.2 Heat Flux to the Substrate	670
	10.4.3 PTA Process Modeling	674
	10.5 Effect of Process Parameter Changes on Coating Properties	676
	10.6 Process Modifications and Adaptations	679
	10.6.1 Variation of Ratio of Pilot Arc Current to Transfer Arc Current	680
	10.6.2 Variation of Powder Feed	680
	10.6.3 Nitriding of Coating	680
	10.6.4 Modulation of Deposition Parameters	681
	10.6.5 High-Energy PTA	682
	10.6.6 PTA Combined with Tape Casting	684
	10.6.7 PTA Deposition with a Negative Work Piece Polarity	684
	10.6.8 Hard Coatings on Magnesium	685
	10.7 Examples of Specific Applications	685
	10.7.1 Increasing Hardness	685
	10.7.2 Increasing Wear Resistance	686
	10.7.3 Abrasive Wear in Petrochemical, Mining, and Agricultural Applications	688
	10.7.4 Combined Corrosion and wear	689
	10.7.5 Refurbishing of Worn Parts	690
	10.7.6 Freestanding Shape Fabrication	690
	10.8 Summary and Conclusions	691
	Nomenclature	692
	References	693
	Chapter 11: Powders, Wires, Cords, and Rods	698
	11.1 Powders	699
	11.1.1 Introduction	699
	11.1.2 Powders Manufacturing Techniques	701
	11.1.2.1 Atomization	701
	(a) Gas Atomization	702
	(b) Gas Atomization of Amorphous Alloys	704
	(c) Water Atomization	706
	11.1.2.2 Fusing and Crushing	708
	11.1.2.3 Milling and Sintering	708
	11.1.2.4 Milling	709
	(a) Ball Milling	709
	(b) Attrition Milling	711
	(c) Cryomilling	711
	(d) Other Techniques	712
	11.1.2.5 Mechanical Alloying and Milling	712
	11.1.2.6 Spray Drying	716
	11.1.2.7 Spheroidization	720
	(a) Plasma Spheroidization of Powders	720
	(b) Production of Spherical Particles from Suspension	725
	11.1.2.8 Cladding	726
	(a) Mechanical Alloying with Attritors	726
	(b) Sintering	726
	(c) Mechanofusion	727
	(d) Deposition from Gaseous Phase	729
	(e) Electrolytic Coatings (Also Called Galvanic Plating)	729
	(f) Chemical Precipitation	730
	11.1.2.9 Sol-Gel and Solutions	730
	(a) Sol-Gel	730
	(b) Solutions	731
	11.1.2.10 Self-Propagating High-Temperature Synthesis	732
	11.1.2.11 Other Methods	734
	(a) Use of Adhesives	734
	(b) Blends	735
	11.1.2.12 Powders with a Metal Matrix in Which Hard Nanometer-Sized Particles Are Uniformly Distributed	735
	(a) Spray Drying Solutions	735
	(b) Integrated Mechanical and Thermal Activation	736
	(c) Other Method	736
	11.1.2.13 Example: Different Powders of ZrO2-8 wt% Y2O3	737
	11.1.3 Examples of the Influence of Powder Morphologies on Coating Properties	739
	11.1.3.1 YSZ Powders	739
	11.1.3.2 Al2O3-TiO2 Powders	739
	11.1.3.3 WC-Co Powders	740
	11.1.3.4 Mechanofused Alumina-Stainless Steel Particles	742
	11.1.3.5 Micrometer-Sized Particles Cold Sprayed	742
	11.1.4 Conventional Particle Classification Method	742
	11.1.4.1 Sieving	743
	11.1.4.2 Air Classification	744
	11.1.5 Characterization	745
	11.1.5.1 Sampling	745
	11.1.5.2 X-ray Diffraction	746
	11.1.5.3 Elements Distribution	746
	11.1.5.4 Composition and Purity	747
	11.1.5.5 Particle Shape	747
	11.1.5.6 Size Distribution	748
	(a) Light Scattering	748
	(b) Coulter Counter	749
	11.1.5.7 Flow Ability	749
	11.1.5.8 Apparent Density	750
	11.1.5.9 Surface Area	751
	11.1.6 Powder Feeders	751
	11.1.6.1 Gravity Fed Hoppers	751
	11.1.6.2 Volumetric Powder Feeders	752
	11.1.6.3 Fluidized-Bed Feeders	754
	11.1.6.4 Powder Feeders for Small Particles	754
	(a) Powder Pump	754
	(b) Vibration Feeder	755
	11.1.6.5 Powder Feed Rate Control	755
	11.1.7 Hazards Related to Particulate Materials	755
	11.1.7.1 Micrometer-Sized Particles	755
	11.1.7.2 Nanomete-Sized Particles	756
	11.2 Wires	757
	11.2.1 Wire Materials	757
	11.2.2 Cored Wires	758
	11.2.3 Wire Feeders	759
	11.3 Rods	759
	11.4 Cords	759
	11.5 Polymer Particles	760
	11.5.1 General Remarks	760
	11.5.1.1 Definitions	760
	11.5.1.2 Polymer Coatings	762
	11.5.2 Sprayed Polymer Powders	762
	11.5.2.1 Polymers	763
	11.5.2.2 Composites Polymer/Ceramic	765
	11.6 Summary and Conclusions	767
	Nomenclature	769
	References	769
	Chapter 12: Surface Preparation	778
	12.1 Introduction	778
	12.2 Machining	778
	12.3 Cleaning	780
	12.3.1 Vapor Degreasing	780
	12.3.2 Baking in an Oven	781
	12.3.3 Ultrasonic Cleaning	781
	12.3.4 Wet or Dry Blasting	781
	12.3.5 Acid Pickling	781
	12.3.6 Brushing	781
	12.3.7 Dry Ice Blasting	782
	12.4 Masking	783
	12.5 Roughening by Grit Blasting	784
	12.5.1 Roughness Measurement	784
	12.5.2 Grit-Blasting Equipment	789
	12.5.3 Grit-Blasting Nozzles	790
	12.5.4 Grit Material	791
	12.5.4.1 Aluminum Oxide	792
	12.5.4.2 Silicon Carbide Grits	793
	12.5.4.3 Angular Chilled Iron	793
	12.5.4.4 Other Grits	794
	12.5.5 Blasting Parameters	794
	12.5.5.1 Impact Angle	795
	12.5.5.2 Blasting Distance	795
	12.5.5.3 Blasting Pressure	796
	12.5.5.4 Blasting Time	796
	12.5.5.5 Influence of the Grit	798
	12.5.5.6 Substrate Young´s Modulus	799
	12.5.6 Grit Residues	799
	12.5.6.1 Grit Residues Characterization	800
	12.5.6.2 Influence of the Blasting Angle	801
	12.5.6.3 Influence of the Blasting Time	801
	12.5.6.4 Influence of the Grit Size	801
	12.5.6.5 Grit Residue Removal	802
	12.5.7 Grit Wear	804
	12.5.8 Residual Stress Induced by Grit Blasting	806
	12.5.9 Conclusion	807
	12.6 High-Pressure Water Jet Roughening	809
	12.6.1 Equipment and Description of the Process	809
	12.6.2 Water Jet-Blasting Parameters	811
	12.6.2.1 Blasting Distance	812
	12.6.2.2 Blasting Time	812
	12.6.2.3 Water Jet Pressure	813
	12.6.2.4 Substrate Material	814
	12.6.3 Comparison Grit and Water Jet Blasting	815
	12.7 Abrasive Water Jetting	816
	12.8 Laser Treatment: Protal Process	816
	12.8.1 Laser Ablation	816
	12.8.2 Protal Experimental Setup	818
	12.8.3 Example of Results	819
	12.8.3.1 Substrate Modifications	819
	12.8.3.2 Splat Formation	821
	12.8.3.3 Coating Adhesion	822
	12.9 Summary and Conclusions	822
	Nomenclature	823
	References	824
	Chapter 13: Conventional Coating Formation	829
	13.1 Introduction	829
	13.2 Spray Parameters	832
	13.3 Physical and Chemical Description of Substrates	834
	13.3.1 Physical Aspect of Substrate Surfaces	835
	13.3.1.1 Substrate Surface Topography	835
	13.3.1.2 Adsorbates and Condensates	835
	13.3.2 Oxide Layer Development on Metals or Alloys	838
	13.3.2.1 General Remarks	838
	13.3.2.2 Different Preheating Processes Used	838
	13.3.2.3 Examples of Oxide Layer Thickness and Composition	840
	13.4 Single Particle Impact, Flattening, and Solidification (When Melted)	842
	13.4.1 Introduction	842
	13.4.1.1 In a Solid State	842
	13.4.1.2 Molten Particles	844
	13.4.2 Different Possibilities of Particle or Splat-Substrate Adhesion	844
	13.4.2.1 Diffusion	844
	13.4.2.2 Crystallographic Structure and Chemical Continuity at the Interface Between Splat and Substrate	846
	13.4.2.3 Adiabatic Softening and Shear Localization	848
	13.4.2.4 Chemical	851
	13.4.2.5 Mechanical	852
	(a) Unmelted Particles	852
	(b) Molten Particles	853
	13.4.3 Splat Formation from Unmelted Particles Impacting on Smooth Substrates	854
	13.4.3.1 Introduction	854
	13.4.3.2 High-Pressure Cold Spray Conditions	855
	13.4.3.3 Unmelted Particles (High Power HVOF or HVAF Sprayed)	857
	13.4.3.4 Unmelted Particles from Low-Pressure Cold Spray	860
	13.4.4 Splat Formation from Molten Particles Impacting onto Smooth Substrates	861
	13.4.4.1 Introduction	861
	(a) Measurements	863
	(b) Modeling	863
	13.4.4.2 The First Instants of Impact	864
	13.4.4.3 Molten Particle Flattening and Solidification	865
	(a) General Remarks	865
	(b) Adsorbates and Condensates: Transition Temperature	868
	(c) Droplet Flattening	871
	(d) Droplet Solidification	874
	(e) Splat Fragmentation	879
	(f) Modeling	880
	(g) Impact of Cermet Particles Normal to the Substrate	883
	13.4.5 Splat Formation from Partially Molten Particles on Smooth Substrates	885
	13.4.5.1 Zirconia Particles Plasma Sprayed	885
	13.4.5.2 Impact of Polymer Particles	885
	13.4.6 Splat Formation from Unmelted Particles Off Normal on Smooth Substrates	888
	13.4.7 Flattening and Solidification of Molten Particle on a Smooth Substrate	888
	13.4.7.1 Impact Splashing	888
	13.4.7.2 Flattening Splashing	889
	13.5 Splat Formation on Rough Surfaces	890
	13.5.1 Solid Ductile Particles	890
	13.5.1.1 High Pressure Cold Spray	890
	13.5.1.2 Low Pressure Cold Spray	891
	13.5.2 Molten Metal, Alloy, Ceramic, and Cermet Particles	891
	13.5.2.1 Idealized Surfaces	891
	13.5.2.2 Real Surfaces	893
	13.5.3 Polymer Particles	895
	13.6 Coating Formation	896
	13.6.1 Molten Particles Deposited by Thermal Spraying	896
	13.6.1.1 Principles of Coating Generation	896
	13.6.1.2 Splat Layering: Motionless Torch and Substrate	901
	13.6.1.3 Splat Layering: Bead Formation	903
	13.6.1.4 Coating: Pass Formation	905
	(a) Effect of Spray Pattern	906
	(b) Other Important Effects	907
	13.6.2 Polymer Coatings	909
	13.6.2.1 Control of Particle in-Flight Melting	909
	13.6.2.2 Substrate Preheating	910
	13.6.2.3 Coating Temperature Control	910
	13.6.2.4 Coating Cooling Rate: Crystallinity	911
	13.6.2.5 Polymer Coatings Post-treatment	911
	13.6.2.6 Polymer Coatings Reinforced with Hard Particles	912
	13.6.3 Ductile Particles	914
	13.6.4 PTA Coatings	918
	13.6.5 Coatings Obtained by Very Low Pressure Plasma Spray	919
	13.6.5.1 Dense and Thin Coatings	919
	13.6.5.2 Coatings from Vapor Phase	920
	13.6.6 Use of Robot Manipulators	922
	13.6.7 Coating Structure Modeling	924
	13.7 Temperature Control of Substrate and Coating in Thermal Spraying	925
	13.7.1 Introduction	925
	13.7.2 Splat Cooling	927
	13.7.3 Cooling Methods	930
	13.7.3.1 Heat Fluxes Contributing to Substrate and Coating Heating	930
	13.7.3.2 Cooling Methods	933
	13.7.4 Coating Mean Temperature Control	935
	13.8 Influence of Powder Manufacturing Process on Coating Properties	937
	13.8.1 Chemical Reactions	937
	13.8.2 Particle Morphology	939
	13.8.3 Nanostructured Agglomerated Particles	941
	13.9 Influence of Wire, Cored Wires, Rods, and Cords on Coating Properties	942
	13.9.1 Flame or HVOF or HVAF-Sprayed Wires	942
	13.9.1.1 Flame Spraying	942
	13.9.1.2 HVOF Spraying	943
	13.9.1.3 HVAF Spraying	943
	13.9.2 Flame-Sprayed Rods	944
	13.9.3 Arc Sprayed	944
	13.9.3.1 Wires	944
	13.9.3.2 Cored Wires	945
	(a) Metals	945
	(b) Ceramics and Cermets	945
	13.10 Stresses Within Coatings	946
	13.10.1 Residual Stress	946
	13.10.1.1 Thermal Stresses	947
	(a) Quenching Stress	948
	(b) Expansion Mismatch Stress	950
	(c) Stress Due to Temperature Gradient	951
	13.10.1.2 Mechanically Induced Stresses	951
	(a) Grit Blasting	951
	(b) Peening Effect	952
	(c) Other Stresses	954
	13.10.1.3 Resulting Residual Stress	955
	13.10.1.4 Effect of Residual Stress on Coating Adhesion	956
	13.10.2 Service Stresses	959
	13.10.2.1 Intrinsic Stresses	960
	13.10.2.2 Thermal Stresses	960
	(a) Thermal Barrier Coatings	960
	(b) Functionally Graded Materials	962
	13.10.2.3 Fatigue of Tribological Coatings	962
	13.10.3 Conclusions Relative to Residual Stresses	963
	13.11 Finishing Coatings	963
	13.11.1 Machining (Turning, Milling)	963
	13.11.2 Grinding	963
	13.11.3 Abrasive Belt Grinding and Polishing	964
	13.11.4 Other Finishing Methods	965
	13.11.4.1 Hand Stoning, Buffing, and Polishing	965
	13.11.4.2 Tumbling and Burnishing	965
	13.12 Post Treatment of Coatings	965
	13.12.1 Fusion of Self-Fluxing Alloys	966
	13.12.1.1 Principle	966
	13.12.1.2 Fusing Processes	966
	13.12.1.3 Fusing Problems	967
	13.12.1.4 Examples of Results	967
	13.12.2 Heat Treating or Annealing	968
	13.12.2.1 Definition	968
	13.12.2.2 Examples of Results	968
	13.12.3 Hot Isostatic Pressing	970
	13.12.4 Austempering Heat Treatment	971
	13.12.5 Laser Glazing	971
	13.12.5.1 Continuous Wave (c.w.) CO2 Lasers	972
	13.12.5.2 Pulsed CO2 Lasers	973
	13.12.5.3 Pulsed Nd/YAG Lasers	973
	13.12.5.4 Power Diode Laser	974
	13.12.6 Sealing	974
	13.12.6.1 General Remarks	974
	13.12.6.2 Sealing Processes	975
	(a) Organic Sealants	975
	(b) Inorganic Sealants	976
	(c) Metals	976
	(d) Other Means	976
	13.12.6.3 Examples of Results	976
	(a) Organic Sealants	976
	(b) Inorganic Sealant	977
	13.12.7 Spark Plasma Sintering	978
	13.12.8 Peening or Rolling Densification	979
	13.12.9 Diffusion	980
	13.13 Summary and Conclusions	980
	Nomenclature	982
	References	984
	Chapter 14: Nanostructured or Finely Structured Coatings	1003
	14.1 Introduction	1004
	14.1.1 Why Nanostructured Coatings	1004
	14.1.2 How to Spray Nanostructure Coatings?	1007
	14.2 Spraying of Complex Alloys Containing Multiple Elements to Form Amorphous Coatings	1009
	14.2.1 Amorphous Alloys Containing Phosphorus	1009
	14.2.2 NiCrB and FeCrB Alloys	1010
	14.2.3 Iron-Based Amorphous Alloys	1011
	14.3 Agglomerated Ceramic Particles Spraying with Hot Gases	1015
	14.3.1 Spray Conditions	1015
	14.3.2 Applications	1026
	14.3.2.1 Wear-Resistant Coatings	1027
	14.3.2.2 Abradable Coatings	1030
	14.3.2.3 Thermal Barrier Coatings	1032
	14.3.2.4 Biomedical Applications	1034
	14.3.2.5 Other Applications	1034
	14.4 Attrition or Ball Milled Cermets or Alloy Particles Sprayed with Hot Gases	1035
	14.4.1 Alloys	1036
	14.4.2 Cermets	1037
	14.4.2.1 WC-Co	1037
	14.4.2.2 Cr3C2-NiCr	1038
	14.4.2.3 Other Cermets	1038
	14.5 Spraying Hypereutectic Alloys with Hot Gases	1039
	14.6 Production of Nanostructured Coatings by Cold Spray	1041
	14.6.1 Alloys	1041
	14.6.2 Composites	1042
	14.6.3 Amorphous Alloys	1044
	14.7 Solutions or Suspensions Spraying	1045
	14.7.1 Sub-Micrometer and Nanometer-Sized Particles in Plasma or HVOF Jets	1046
	14.7.1.1 Particle Inertia	1046
	14.7.1.2 Particle Trajectory	1048
	14.7.1.3 Particle Flattening	1051
	14.7.1.4 Particle Heat Transfer	1052
	14.7.2 Liquid Injection	1052
	14.7.2.1 Radial Injection into Plasma and HVOF Jets	1052
	14.7.2.2 Axial Injection	1055
	(a) d.c. Plasmas	1055
	(b) HVOF	1056
	(c) r.f. Plasmas	1057
	14.7.3 Spray Torches Used	1059
	14.7.3.1 General Remarks	1059
	14.7.3.2 d.c. Plasma Torches Used	1060
	14.7.3.3 r.f. Torches Used	1062
	14.7.3.4 HVOF Torches Used	1062
	14.7.4 Solutions or Suspensions Preparation	1062
	14.7.4.1 Solutions	1063
	14.7.4.2 Suspensions	1065
	14.7.4.3 Sol Preparation: A New Process Called ``PROSOL´´	1066
	14.7.4.4 Suspensions of Amorphous Powders	1066
	14.7.5 Liquid Stream: Hot Flow Interactions	1067
	14.7.5.1 General Remarks	1067
	14.7.5.2 Solutions	1070
	14.7.5.3 Suspensions	1075
	14.7.5.4 Conclusions	1077
	14.7.6 Coating Manufacturing Mechanisms	1078
	14.7.6.1 Splats	1078
	(a) Solutions	1078
	(b) Suspensions	1079
	14.7.6.2 Spray Beads	1081
	(a) Solutions	1082
	(b) Suspensions	1084
	14.7.6.3 Coatings	1085
	(a) Solutions	1086
	(b) Suspensions	1087
	(i) Plasma Spraying	1087
	Influence of Particle Morphologies and Size Distributions	1087
	Unmolten Tiny Particles	1096
	Lamellar or Granular Structures	1098
	Spraying Mixtures of Powders	1099
	(ii) HVOF Spraying (HVSFS)	1101
	14.7.6.4 Environmental Impact (Life Assessment Impact: LCA)	1104
	14.7.7 Applications	1105
	14.7.7.1 Thermal Barrier Coatings	1105
	(a) Solutions	1105
	(b) Suspensions	1106
	14.7.7.2 Solid Oxy-Fuel Cell Components	1107
	14.7.7.3 Wear-Resistant Coatings	1108
	(a) WC-Co	1108
	(b) Alumina	1108
	(c) Zirconia-Alumina	1110
	(d) Alumina-Zirconia-Yttria	1111
	(e) TiO2-TiC Coatings	1111
	14.7.7.4 Titania Photo-Catalytic Coatings	1111
	14.7.7.5 Coatings for Medical Applications	1112
	14.7.7.6 Anti-Corrosion Coatings	1114
	14.7.7.7 SnO2 Layers	1114
	14.7.7.8 Inconel Coatings	1114
	14.7.7.9 Antierosion Coatings	1115
	14.7.7.10 Adhesive Layer on Smooth and Thin Substrate	1115
	14.8 Summary and Conclusions	1115
	Nomenclature	1117
	References	1118
	Chapter 15: Coating Characterizations	1134
	15.1 Introduction to Coating Characterizations and Testing Methods	1136
	15.1.1 Differences Between Coatings and Bulk Materials	1136
	15.1.2 Characterization and Testing Methods Used for Coatings	1137
	15.1.3 Statistical Methods	1138
	15.1.3.1 (a) Normal Distribution	1139
	15.1.3.2 (b) Weibull Statistic	1140
	15.1.3.3 (c) Variance	1141
	15.2 Nondestructive Methods	1142
	15.2.1 Visual Inspection	1142
	15.2.2 Laser Inspection	1143
	15.2.3 Coordinate Measuring Machines	1143
	15.2.4 Machine Vision and Robotic Evaluation	1143
	15.2.5 Acoustic Emission	1144
	15.2.6 Laser-Ultrasonic Techniques	1144
	15.2.7 Thermography	1145
	15.2.8 Coating Thickness	1146
	15.3 Metallography and Image Analysis	1146
	15.3.1 Coating Preparation	1147
	15.3.1.1 Sectioning	1147
	(a) Abrasive Cutting	1147
	(b) Precision Sectioning	1147
	15.3.1.2 Mounting	1148
	15.3.1.3 Grinding	1149
	15.3.1.4 Polishing	1150
	15.3.1.5 Etching	1151
	15.3.1.6 Focused Ion Beam	1151
	15.3.1.7 Examples of Conventional Coatings Preparation	1151
	15.3.2 Microscopy	1152
	15.3.2.1 Optical Microscopy	1152
	15.3.2.2 Scanning Electron Microscopy	1153
	15.3.2.3 Image Analysis	1155
	15.3.2.4 Atomic Force Microscopy	1156
	15.3.2.5 Transmission Electron Microscopy	1157
	15.4 Materials Characterization	1158
	15.4.1 X-Ray Spectroscopy or X-Ray Fluorescence	1159
	15.4.2 Infrared Spectroscopy	1159
	15.4.3 Mössbauer Spectroscopy	1160
	15.4.4 X-Ray Diffraction	1160
	15.4.5 Small- and Ultrasmall-Angle X-Ray Diffraction (USAXF)	1162
	15.4.6 Neutron Scattering	1164
	15.4.7 X-Ray Absorption Spectroscopy	1166
	15.4.8 Electron Probe X-Ray Microanalysis	1167
	15.4.9 Auger Electron Spectroscopy	1167
	15.4.10 X-Ray Photoelectron Spectroscopy	1167
	15.4.11 Other Techniques	1168
	15.5 Void Content and Network Architecture	1168
	15.5.1 Archimedean Porosimetry	1170
	15.5.2 Mercury Intrusion Porosimetry (MIP)	1171
	15.5.3 Gas Permeation and Pycnometry	1171
	15.5.4 Small-Angle Neutrons Scattering	1173
	15.5.5 Ultrasmall-Angle X-Ray Scattering	1174
	15.5.6 Stereological Protocols (Coupled to Image Analysis) (ST)	1176
	15.5.7 Electrochemical Impedance Spectroscopy	1181
	15.6 Adhesion-Cohesion	1182
	15.6.1 Introduction	1182
	15.6.2 Simple Adhesion Tensile Test	1183
	15.6.3 Other Types of Tensile Tests	1185
	15.6.4 Shear Stress	1187
	15.6.5 Fracture Mechanics Approach	1188
	15.6.6 Bending Test: Adhesion and Interface Toughness Measurements	1190
	15.6.7 Indentation: Interface Toughness Measurement	1192
	15.6.8 Other Methods	1194
	15.6.8.1 Double Cantilever Beam Test	1194
	15.6.8.2 Double Torsion Test	1195
	15.6.8.3 Scratch Test	1195
	15.6.8.4 Laser Shock	1196
	(a) Coating Adhesion	1196
	(b) Splat Adhesion	1197
	15.7 Mechanical Properties	1198
	15.7.1 Hardness and Indentation Test	1198
	15.7.1.1 Hardness	1198
	15.7.1.2 Indentation	1202
	15.7.2 Young´s Modulus	1205
	15.7.2.1 Indentation	1205
	15.7.2.2 Four-Points Bending	1206
	15.7.2.3 Knoop Hardness	1206
	15.7.2.4 Ultrasound Propagation	1206
	15.7.3 Toughness	1207
	15.7.4 Residual Stress	1208
	15.7.4.1 X-Ray Diffraction	1208
	15.7.4.2 Neutron Diffraction	1209
	15.7.4.3 Material Removal	1210
	(a) Layer Removal Method	1211
	(b) Hole Drilling Method	1211
	15.7.4.4 Bending	1212
	15.8 Thermal Properties	1214
	15.8.1 Mass Density	1214
	15.8.2 Expansion Coefficient	1215
	15.8.3 Thermal Conductivity and Thermal Diffusivity	1215
	15.8.4 Specific Heat at Constant Pressure	1217
	15.8.5 Thermal Shock Resistance	1218
	15.8.6 Differential Thermal Analysis, Thermogravimetry, and Differential Scanning Calorimetry	1220
	15.8.6.1 (a) Phase Changes	1221
	15.8.6.2 (b) Reactive Plasma Spraying	1222
	15.8.6.3 (c) Oxidation Resistance	1223
	15.9 Wear Resistance	1224
	15.9.1 Abrasive Wears	1224
	15.9.2 Adhesive Wears	1225
	15.9.3 Erosive Wear	1227
	15.9.4 Surface Fatigue	1230
	15.9.5 Corrosive Wears	1234
	15.9.6 Fretting	1238
	15.10 Corrosion Resistance	1239
	15.10.1 General Remarks	1239
	15.10.2 Corrosion Characterization	1243
	15.10.2.1 (a) Electrochemical Measurements	1243
	15.10.2.2 (b) Fog and Salt-Spray Test	1245
	15.10.2.3 (c) Molten Salt	1245
	15.10.2.4 (d) Oxidation	1246
	15.11 Summary and Conclusions	1246
	Nomenclature	1247
	ASTM Standards	1249
	A: Adhesion-Cohesion	1249
	C: Corrosion	1250
	M: Mechanical Properties	1251
	Ma: Materials Characterization	1252
	Me: Metallography and Image Analysis	1253
	ND: Non-destructive Methods	1253
	S: Statistical Methods	1253
	T: Thermal Properties	1253
	V: Void Content and Network Architecture	1254
	W: Wear	1254
	References	1256
	Chapter 16: Process Diagnostics and Online Monitoring and Control	1272
	16.1 Introduction	1273
	16.1.1 What Is Expected from Thermal-Sprayed Coatings?	1273
	16.1.2 Coatings Repeatability, Reliability, and Reproducibility	1273
	16.1.3 How Sprayed Coatings Quality Was Improved Through the Spray Process Monitoring	1276
	16.1.3.1 At the Beginning	1276
	16.1.3.2 Eighties-Nineties	1276
	16.1.3.3 Mid-1990s to Now: Development of Sensors	1278
	16.1.4 Spray Process Parameters That Should Be Controlled	1278
	16.2 High-Energy Jets Characterization	1279
	16.2.1 Plasma Jets	1280
	16.2.1.1 Temperature Measurements	1280
	(a) Emission Spectroscopy of Symmetrical Jets	1280
	(b) Emission Spectroscopy of Nonsymmetrical Jets	1283
	(c) Laser Spectroscopy for Jets at Temperatures Below 8,000 K	1284
	16.2.1.2 Velocity Measurements	1284
	16.2.1.3 Turbulences Characterization	1285
	16.2.1.4 Electrode Erosion	1286
	16.2.2 Flames and Cold Spray	1287
	16.2.2.1 Flame Temperatures	1288
	(a) Laser	1288
	(b) Thermocouple	1289
	16.2.2.2 Flame and Cold Flow Velocity Measurements: PIV	1289
	16.2.2.3 Measurements Based on Laser Scattering	1290
	16.2.2.4 Turbulences	1290
	16.3 Sensors	1290
	16.3.1 Hot Gases Flow: Enthalpy Probe	1291
	16.3.1.1 Incompressible Jets	1292
	16.3.1.2 Subsonic Jets	1293
	16.3.1.3 Supersonic Jets	1293
	16.3.1.4 Precision of Measurements	1293
	16.3.1.5 Example of Results	1294
	16.3.2 Particles In-Flight Distribution	1295
	16.3.2.1 Hot Particles	1297
	16.3.2.2 Cold Particles	1302
	16.3.2.3 Liquid Injection	1303
	16.3.3 In-Flight Hot Particle Temperature and Velocity Measurement	1305
	16.3.3.1 Ensemble or Local Measurements	1305
	16.3.3.2 Particle Temperature and Velocity Measurements	1310
	(a) Principle of the Different Sensors	1310
	(b) Calibration Problems	1313
	(c) Example of Results	1313
	(i) Plasma Spraying	1313
	(ii) HVOF Spraying	1319
	(iii) Wire Arc	1321
	16.3.3.3 Transient Measurements of Particle Temperatures and Velocities	1321
	16.3.3.4 Particle Temperature Measurements	1323
	16.3.3.5 Particle Size or Diameter	1323
	16.3.4 In-Flight Velocity Measurements of Cold Particles	1324
	16.3.5 Are Such Measurements Sufficient to Monitor Coating Properties?	1327
	16.3.5.1 Conventional Hot Processes	1327
	16.3.5.2 Cold Spray	1329
	16.3.6 Coating Under Formation	1329
	16.3.6.1 Hot Gases Heat Flux	1329
	16.3.6.2 Substrate Temperature Control	1330
	16.3.6.3 Stress Development During Spraying	1330
	16.3.6.4 Coating Thickness Measurement	1331
	16.4 Online Control or Monitoring?	1332
	16.4.1 Coating Properties Monitoring	1332
	16.4.1.1 Spray Pattern Through Robot Trajectory Planning	1332
	16.4.1.2 Coating Monitoring Through In-Flight Particle Parameters	1333
	16.4.1.3 Artificial Neural Networks and Fuzzy Logic	1336
	16.4.2 Online Control?	1341
	16.5 Other Possible Measurements	1341
	16.5.1 Particle Vaporization	1341
	16.5.2 Splat Formation	1342
	16.5.2.1 Case of Molten or Semimolten Particles	1342
	(a) Interface Splat-Substrate	1342
	(b) Modeling	1343
	(c) Flattening and Cooling Measurements	1344
	16.5.2.2 Case of Unmelted Particles	1348
	16.5.3 Plasma-Liquid Injection	1349
	16.5.3.1 Particle Imaging Velocity	1349
	16.5.3.2 Shadography	1350
	16.5.3.3 Infrared Detection of Liquid Injection	1353
	16.6 Summary and Conclusions	1354
	Nomenclature	1357
	References	1358
	Chapter 17: Process Integration	1372
	17.1 Introduction	1373
	17.2 Potential and Real Risks	1373
	17.2.1 Powders: Respiratory Problems and Explosions	1374
	17.2.1.1 Particles and Pulmonary System	1374
	17.2.1.2 Toxicity of Powders	1375
	17.2.1.3 Explosiveness of Powders	1375
	17.2.2 Gases	1376
	17.2.2.1 Gases Used for the Spray Process	1376
	17.2.2.2 Gases Resulting from the Spray Process	1377
	17.2.2.3 Gases Storage	1378
	17.2.3 Prevention and Safety Measures	1378
	17.2.3.1 Powders	1379
	17.2.3.2 Gases	1379
	17.2.4 Other Risks	1380
	17.2.4.1 Noise	1380
	17.2.4.2 Radiation	1381
	17.2.4.3 Thermal Risks	1382
	17.2.4.4 Electric Risks	1382
	17.2.4.5 Risks Associated with the Use of Robots	1382
	17.3 Ancillary Equipment	1383
	17.3.1 The Spray Booth	1383
	17.3.1.1 What for?	1383
	17.3.1.2 Typical Design	1383
	17.3.2 Exhaust Systems	1386
	17.3.3 Power Supply	1386
	17.3.4 Gas Supply	1387
	17.3.5 Compressed Air Supply	1387
	17.3.6 Cooling Water	1387
	17.3.7 Micrometer-Sized Powder Feeders and Solutions or Suspensions Feeders	1388
	17.3.8 Gun Movements	1389
	17.3.9 Control Panel	1389
	17.4 Controlled Atmosphere	1389
	17.4.1 Soft Vacuum Plasma Spraying	1389
	17.4.2 Vapor Phase Deposition	1394
	17.4.3 Inert Plasma Spraying	1395
	17.4.4 Cold Spray with Helium	1396
	17.5 Finishing and Post-Treatment of Coatings	1396
	17.5.1 Finishing	1397
	17.5.1.1 Machining (Turning, Milling)	1397
	17.5.1.2 Grinding	1397
	17.5.1.3 Abrasive Belt Grinding and Polishing	1398
	17.5.1.4 Super Finishing	1399
	17.5.1.5 Other Finishing Methods	1399
	(a) Hand Stoning, Buffing, and Polishing	1399
	(b) Tumbling and Burnishing	1399
	17.5.2 Fusion of Self-Fluxing Alloys	1399
	17.5.2.1 Principle	1399
	17.5.2.2 Fusing Processes	1400
	17.5.2.3 Examples of Results	1401
	17.5.3 Heat Treating or Annealing	1402
	17.5.3.1 Definition	1402
	17.5.3.2 Examples of Results	1402
	17.5.4 Hot Isostatic Pressing	1404
	17.5.5 Austempering Heat Treatment	1405
	17.5.6 Laser Glazing	1405
	17.5.7 Sealing	1408
	17.5.7.1 General Remarks	1408
	17.5.7.2 Sealing Processes	1408
	(a) Organic Sealants	1409
	(b) Inorganic Sealants	1409
	(c) Metals	1410
	(d) Other Means	1410
	17.5.7.3 Examples of Results	1410
	(a) Organic Sealants	1410
	(b) Inorganic Sealant	1410
	17.5.8 Spark Plasma Sintering	1413
	17.5.9 Peening or Rolling Densification	1413
	17.5.10 Diffusion	1414
	17.6 Summary and Conclusions	1414
	Nomenclature	1415
	References	1415
	Chapter 18: Industrial Applications of Thermal Spraying Technology	1422
	18.1 Introduction	1424
	18.2 Advantages and Limitations of the Different Spray Processes	1425
	18.2.1 Flame Spraying	1425
	18.2.1.1 Powders	1426
	(a) As-Sprayed Coating	1426
	(b) Remelted Coating (Flame, Furnace, Induction)	1426
	18.2.1.2 Wire, Rod, or Cord	1426
	18.2.2 D-Gun Spraying	1427
	18.2.3 HVOF-HVAF Spraying	1427
	18.2.4 Wire Arc Spraying	1428
	18.2.5 Plasma Spraying	1428
	18.2.5.1 Air Plasma Spraying	1429
	18.2.5.2 Inert Atmosphere Plasma Spraying	1429
	18.2.5.3 Vacuum d.c. Plasma Spraying (VPS)	1429
	18.2.5.4 Induction Plasma Spraying (VIPS)	1430
	18.2.6 Plasma-Transferred Arcs (PTA)	1430
	18.2.7 Plasma Transferred Arc	1431
	18.2.8 Cold Spray	1432
	18.3 Thermal-Sprayed Coating Applications	1432
	18.3.1 Wear Resistant Coatings	1433
	18.3.1.1 Abrasive Wears	1433
	(a) Self-Fluxing Alloys	1433
	(b) Cermet Coatings, Especially Those HVOF or HVAF Sprayed	1434
	18.3.1.2 Erosive Wear	1436
	18.3.1.3 Friction and Adhesive Wears	1438
	(a) Ceramic Materials	1439
	(b) Cermets	1440
	(c) Metals	1442
	(d) Polymers	1443
	18.3.1.4 Scuffing	1443
	18.3.1.5 Cavitation Wear	1444
	18.3.1.6 Surface Fatigue Wear	1445
	18.3.1.7 Wear by Fretting and Fretting-Corrosion	1447
	18.3.1.8 Thermal Fatigue and Thermal Shock	1449
	(a) Thermal Fatigue	1449
	(b) Thermal Shock	1450
	18.3.1.9 Wear by Very High Stresses	1452
	18.3.2 Corrosion and Oxidation Resistant Coating	1454
	18.3.2.1 Room Temperature Corrosion	1454
	(a) Atmospheric and Marine Corrosion	1454
	(b) Chemical or Parachemical Corrosion	1456
	18.3.2.2 High Temperature Corrosion	1459
	18.3.2.3 Oxidation	1462
	18.3.2.4 Corrosive Wear	1464
	(a) Low Temperature	1465
	(b) High Temperature	1466
	18.3.3 Thermal Protection Coatings	1467
	18.3.3.1 Thermal Barrier Coatings for Aero Engines	1468
	(a) Conventional Plasma Spraying	1469
	(b) New Spray Processes	1472
	(c) Coatings Against Fretting	1473
	18.3.3.2 Thermal Barrier Coatings for Land-Based Turbines	1473
	18.3.3.3 Thermal Barrier Coatings for Diesels	1475
	18.3.3.4 Other Applications	1475
	18.3.4 Clearance Control Coatings	1476
	18.3.5 Bonding Coatings	1478
	18.3.6 Electrical and Electronic Coatings	1479
	18.3.6.1 Dielectrics	1480
	18.3.6.2 Resistors and Conductors	1481
	18.3.6.3 Electronic Devices	1481
	18.3.6.4 Electromagnetic Shielding	1482
	18.3.6.5 Magnetic Materials	1482
	18.3.6.6 Sensor Applications	1483
	18.3.6.7 Other Applications	1483
	18.3.7 Freestanding Spray-Formed Parts	1483
	18.3.8 Medical Applications	1487
	18.3.9 Replacement of Hard Chromium	1490
	18.3.10 Applications Under Developments	1492
	18.3.10.1 Solid Oxide Fuel Cells	1492
	18.3.10.2 Other Sensors	1493
	18.3.10.3 Decorative Coatings	1494
	18.3.10.4 Spent Nuclear Fuel	1494
	18.3.10.5 Combined Cycle Power Plant Combinations	1495
	18.3.10.6 Future Nuclear Fusion Reactor	1495
	18.4 Thermal-Sprayed Coatings by Industry	1495
	18.4.1 Aerospace	1496
	18.4.2 Land-Based Turbines	1499
	18.4.3 Automotive	1499
	18.4.3.1 Power Train Components	1500
	18.4.3.2 Rebuilding and Dimensional Restoration	1502
	18.4.3.3 Thermal Barrier Coatings (See Sect.18.3.3.3)	1502
	18.4.3.4 Other Applications	1502
	18.4.4 Electrical and Electronic Industries	1502
	18.4.5 Corrosion Applications for Land-Based and Marine Applications	1504
	18.4.5.1 Sacrificial Coatings	1504
	18.4.5.2 No-Sacrificial Coatings	1506
	18.4.6 Medical Applications	1507
	18.4.7 Ceramic and Glass Manufacturing	1508
	18.4.8 Printing Industry	1509
	18.4.9 Pulp and Paper	1511
	18.4.10 Metal Processing Industries	1513
	18.4.10.1 Components of Furnaces or Boilers	1513
	18.4.10.2 Molds	1515
	18.4.10.3 Die Casting	1515
	18.4.10.4 Entrance and Exit Rolls of Steel Processing Line	1516
	18.4.10.5 Galvanized and Aluminized Steel Sheets	1516
	18.4.11 Petroleum and Chemical Industries	1516
	18.4.12 Electrical Utilities	1519
	18.4.12.1 For Fluidized Bed Combustor Boilers	1519
	18.4.12.2 For Coal-Fired Boilers	1519
	18.4.13 Textile and Plastic Industries	1520
	18.4.14 Polymers	1520
	18.4.15 Reclamation	1522
	18.4.16 Other Applications	1524
	18.4.17 Thermal-Sprayed Coatings in the Different Countries	1526
	18.5 Economic Analysis of the Different Spray Processes	1534
	18.5.1 Different Cost Contribution Factors	1534
	18.5.2 Direct Cost Factors	1535
	18.5.2.1 The Cost of Materials	1535
	18.5.2.2 The Cost of Gases, Electricity, and Consumables	1537
	18.5.2.3 Direct Labor Cost	1541
	18.5.2.4 Direct Cost for Quality Control, Packing, and Labeling	1541
	18.5.3 Indirect or Fixed Cost Factors	1542
	18.5.3.1 Capital Investments	1542
	18.5.3.2 Other Indirect or Fixed Costs	1543
	18.5.4 Few Examples	1543
	18.5.4.1 Cost of d.c. Plasma Spraying of Partially Yttria-Stabilized Zirconia	1543
	18.5.4.2 MCrAlY Coatings Sprayed by Arc Spray and High-Power Plasma Spraying	1545
	18.5.4.3 Manual Wire Flame Zn Coating per Square Meter	1546
	18.5.4.4 Cost Comparison Between APS and Wire Arc for NiAl (Aeronautic)	1546
	18.5.4.5 Cost Comparison for Hard Chromium Replacement on a Jack	1548
	18.6 Summary and Conclusions	1550
	Appendix: Use of the Different Spray Materials	1551
	A.1 Metals	1551
	A.2 Ceramics (Oxides)	1560
	A.3 Cermets	1563
	A.4 Abradables	1564
	Nomenclature	1565
	References	1566