Foreword ....................................................... xv
Introduction ................................................. xvii
Contributors .................................................. xxi
1 Superlubricity for Incommensurate Crystalline and
Disordered Interfaces ........................................ 1
J.B. Sokoloff ................................................ 1
1.1 Superlubricity for Incommensurate Interfaces ............ 1
1.2 Superlubricity for Disordered Interfaces ................ 3
1.3 Friction Resulting from Multiscale Roughness ............ 6
1.4 Superlubricity Resulting from Polymer Brushes .......... 11
1.5 Conclusions ............................................ 14
References .................................................. 14
2 Superlubricity of Clean Surfaces ............................ 17
M. Hirano ................................................... 17
2.1 Introduction ........................................... 17
2.2 Preliminaries: Tomlinson's Picture ..................... 18
2.3 The Criterion for the Occurrence of Tomlinson's
Mechanism .............................................. 21
2.4 Atomistic Origin of Friction ........................... 25
2.4.1 Frictional Model ................................ 25
2.4.2 Static Friction ................................. 26
2.4.3 Dynamic Friction: Energy Dissipation ............ 27
2.5 Superlubricity ......................................... 30
2.5.1 Superlubricity and Adiabatic Motion of Atoms .... 30
2.5.2 Friction Diagram ................................ 31
2.5.3 Superlubricity and High Dimensionality .......... 33
2.5.4 Energy Recurrence Phenomena ..................... 34
2.6 Summary ................................................ 36
References .................................................. 37
3 Theoretical Studies of Superlubricity ....................... 39
С.Е. Сатраñá and M.H. Müser ................................. 39
3.1 Introduction ........................................... 39
3.2 Theory ................................................. 40
3.2.1 Friction and Superlubricity ..................... 40
3.2.2 Dry Friction on Idealized Zero Temperature
Analytic Models ................................. 41
3.2.1 Disorder, Symmetry and Dimensionality ........... 44
3.2.4 Thermal and Quantum Effects ..................... 46
3.3 Computer Simulations ................................... 47
3.3.1 Rough Interfaces, Elastic Solids and
Superlubricity .................................. 47
3.3.2 Lennard-Jones Systems ........................... 50
3.3.3 Adsorbed Layers, Confined Fluids and Boundary
Lubrication ..................................... 51
3.3.4 Solid Lubricants and Layered Structures ......... 52
3.3.5 Metallic Contacts ............................... 53
3.3.6 Carbon Films and Hydrogen-Terminated Surfaces ... 54
3.4 Conclusions ............................................ 54
References .................................................. 55
4 Ab-initio Atomic Scale Study of Nearly Frictionless
Surfaces .................................................... 57
S. Ciraci, T. Yildirim, S. Dag and O. Gulseren .............. 57
4.1 Introduction ........................................... 57
4.2 Frictionless Sliding ................................... 59
4.2.1 General Theoretical Arguments ................... 59
4.2.2 Recent Experimental Progress .................... 60
4.3 Description of Theoretical Model ....................... 60
4.3.1 Atomistic Models and Details for Ab-initio
Calculations .................................... 60
4.4 Superlow Friction Coefficient Between Hydrogenated
Diamond Surfaces ....................................... 61
4.4.1 Force Variations in the Sliding Friction of
Two Hydrogenated Diamond Surfaces ............... 63
4.4.2 Sliding Friction of Hydrogenated Diamond (001)
Slabs ........................................... 63
4.4.3 Effect of Oxidation ............................. 67
4.5 Ab-initio Study of Atomic-Scale Friction Between
Cubic BN-Surfaces ...................................... 68
4.6 Conclusions ............................................ 75
Acknowledgements ............................................ 75
References .................................................. 76
5 Molecular Dynamics Simulations of Tribology ................. 79
J.D. Schall, P.T. Mikulski, G.M. Chateauneuf, G. Gao and
J.A. Harrison ............................................... 79
5.1 Introduction ........................................... 79
5.2 MD Simulation Methods .................................. 80
5.2.1 Outline of Method ............................... 80
5.2.2 Simulation of Tribology ......................... 83
5.3 Reactive Potentials .................................... 84
5.3.1 Covalent Potentials ............................. 84
5.3.2 Development and Fitting of Bond-Order
Potential ....................................... 88
5.3.3 Covalent + Intermolecular Forces (AIREBO) ....... 91
5.4 Recent MD Work ......................................... 92
5.4.1 Tribochemistry at the Sliding Interface ......... 92
5.4.2 Intrafilm Tribochemistry ........................ 96
5.4.3 Self-assembled Monolayers ....................... 98
5.5 Conclusion ............................................ 100
Acknowledgements ........................................... 100
References ................................................. 100
6 What Causes Low Friction; What Causes High Friction ........ 103
Y. Zhu and S. Granick ...................................... 103
6.1 Introduction .......................................... 103
6.2 Superlubricity in Boundary Lubrication ................ 103
6.3 Controlling the Boundary Condition of Hydrodynamic
Flow .................................................. 108
6.3.1 The Mechanism that Controls Slip in
Low-viscosity Fluids ........................... 109
6.3.2 "Slip" at Partially-Wetted Surfaces with
Roughness Varied ............................... 110
6.3.3 "Slip" Can Be Modulated by Dissolved Gas—at
Both Wetted and Partially-Wetted Surfaces ...... 112
6.4 Outlook—The Purposeful Reduction in Friction .......... 114
6.5 Concluding Remarks .................................... 115
Acknowledgements ........................................... 115
References ................................................. 115
7 Frictional Dynamics at the Atomic Scale in Presence of
Small Oscillations of the Sliding Surfaces ................. 119
S. Jeon, T. Thundat and Y. Braiman ......................... 119
7.1 Introduction .......................................... 119
7.2 Experimental .......................................... 120
7.2.1 Results and Discussion ......................... 121
7.2.2 Summary ........................................ 129
Acknowledgements ........................................... 129
References ................................................. 129
8 Effect of Surface Roughness and Adsorbates on
Superlubricity ............................................. 131
V.N. Samoilov, C. Yang, U. Tartaglino and B.N.J. Persson ... 131
8.1 Introduction .......................................... 131
8.2 Model ................................................. 132
8.3 Numerical Results ..................................... 134
8.3.1 Clean Smooth and Rough Surfaces ................ 134
8.3.2 Dependence of the Friction on the Load ......... 137
8.3.3 Role of Adsorbates ............................. 143
8.4 Summary and Conclusion ................................ 145
Acknowledgements ........................................... 146
References ................................................. 146
9 Atomic-Scale Investigation of Superlubricity on
Insulating Surfaces ........................................ 147
E. Gnecco, A. Socoliuc and E. Meyer ........................ 147
9.1 Introduction .......................................... 147
9.2 The Tomlinson-Prandtl Model ........................... 148
9.3 The Superlubric Regime ................................ 152
9.4 Experimental Evidence of Superlubricity: Quasistatic
Case .................................................. 154
9.1 Experimental Evidence of Superlubricity: Dynamic
Case .................................................. 157
9.6 Conclusions and Outlook ............................... 159
References ................................................. 160
10 Superlubricity of Fullerene Intercalated Graphite
Composite .................................................. 161
K. Miura and N. Sasaki ..................................... 161
10.1 Introduction .......................................... 161
10.2 Sliding of Graphite Flakes ............................ 162
10.2.1 Sliding of Graphite Flakes over Graphite ....... 162
10.2.2 Lateral Force versus Load Acting between
Graphite Surfaces .............................. 164
10.3 Superlubricity of a Graphite/С60 Monolayer Film/
Graphite .............................................. 165
10.3.1 Structure of a Graphite/С60 Monolayer
Film/Graphite System ........................... 165
10.3.2 Ultralow Lateral Movement of Сбо Molecules ..... 166
10.4 Superlubricity of С60 (C70) Intercalated Graphite
Composite ............................................. 168
10.4.1 Preparation and Structure of С60 (C70)
Intercalated Graphite Composite ................ 168
10.4.2 Superlubricity of С60 (C70) Intercalated
Graphite Composite ............................. 171
10.5 Origin of Superlubricity of Fullerene Intercalated
Graphite Composite .................................... 172
10.5.1 Elastic Property of New Composite .............. 172
10.5.2 Internal Sliding of New Composite .............. 173
10.5.3 Guideline for Designing Ultralow Friction
System ......................................... 175
10.5.4 Intercalated Fullerenes Can Control Ultralow
Friction ....................................... 176
References ................................................. 177
11 Superlubricity of Ag Nanometer-Thick Layers under
Macroscopic Sliding System in UHV Condition ................ 179
M. Goto and F. Honda ....................................... 179
11.1 Introduction .......................................... 179
11.2 Experimental Details .................................. 180
11.3 Film-Thickness Effect on the Lubricity of Ag Film ..... 182
11.4 Determination of the Shear Plane in Superlubricity
of Ag Film ............................................ 186
11.5 Morphological Effect on Superlubricity ................ 188
11.6 Effect of Crystal Orientation on Superlubricity ....... 192
11.7 Origin of Ag Film Superlubricity ...................... 195
11.8 Conclusion ............................................ 197
References ................................................ 198
12 Superlubricity between Graphite Surfaces ................... 199
M. Dienwiebel and J.W.M. Frenken ........................... 199
12.1 Introduction .......................................... 199
12.2 Incommensurability-Induced Transition to Frictionless
Sliding ............................................... 200
12.3 Atomic-Scale Observation of Superlubricity between
Graphite Surfaces ..................................... 200
12.4 Towards Applications .................................. 204
12.5 Summary ............................................... 205
Acknowledgements ........................................... 206
References ................................................. 206
13 Superlubricity of Molybdenum Disulfide ..................... 207
J.M. Martin ................................................ 207
13.1 Low, Ultralow and Superlow Friction ................... 207
13.2 Characterization of Sputter-Deposited MoS2 Coatings ... 208
13.3 Experimental Details for UHV Tribometry and MoS2
Film Deposition ....................................... 210
13.4 Ultralow and Superlow Friction of MoS2 Coatings ....... 210
13.5 HRTEM Investigation of MoS2 Wear Debris ............... 216
13.6 Possible Explanation for Superlubricity of MoS2 ....... 217
13.7 Ultralow Friction by MoS2 Single Sheets. Towards
Superlubricity under Boundary Lubrication ............. 220
13.8 Ultralow Friction by MoS2 Nanoparticles ............... 223
13.8.1 Nanotribology on MoS2 Crystals ................. 223
References ................................................. 224
14 Superlubricity of Tungsten Disulfide Coatings in Ultra
High Vacuum ................................................ 227
L. Joly-Pottuz and M. Iwaki ................................ 227
14.1 Introduction .......................................... 227
14.2 WS2 Coatings .......................................... 228
14.3 IF-WS2 coatings ....................................... 230
14.4 Conclusions ........................................... 235
Acknowledgements ........................................... 235
References ................................................. 235
15 Superlubricity by H2S Gas Lubrication of Mo ................ 237
I.L. Singer and T. Le Mogne ................................ 237
Abstract ................................................... 237
15.1 Introduction .......................................... 237
15.2 Experimental .......................................... 239
15.2.1 Friction and Surface Analysis Apparatus ........ 239
15.2.2 Sample Preparation and Friction Test
Procedures ..................................... 239
15.3 Results ............................................... 240
15.3.1 Friction Coefficient vs. Gas Pressure .......... 240
15.3.2 Friction Coefficient vs. Speed ................. 245
15.4 Discussion ............................................ 247
15.5 Conclusions ........................................... 250
Acknowledgements ........................................... 250
References ................................................. 250
16 Superlubricity in Diamondlike Carbon Films ................. 253
A. Erdemir and O.L. Eryilmaz ............................... 253
16.1 Introduction .......................................... 253
16.2 Superlubricity in Crystalline Solids .................. 254
16.2.1 Lamellar Solids ................................ 254
16.2.2 Other Solids ................................... 256
16.3 Superlubricity in Amorphous Carbons ................... 257
16.3.1 Diamondlike Carbon Films ....................... 258
16.3.2 Synthesis and Main Characteristics of DLC
Films .......................................... 258
16.3.3 Classification ................................. 259
16.3.4 Lubrication Mechanisms ......................... 259
16.3.5 Origin of Superlubricity in DLC Films .......... 262
16.4 Summary and Future Direction .......................... 268
Acknowledgements ........................................... 269
References ................................................. 269
17 Superlow Friction of a-C:H Films: Tribochemical and
Rheological Effects ........................................ 273
J. Fontaine and C. Donnet .................................. 273
17.1 Introduction .......................................... 273
17.2 The Wide Friction Range of DLC Films .................. 274
17.2.1 General Behavior ............................... 274
17.2.2 Experimental Evidence of Superlow Friction ..... 275
17.3 Conditions for a-C:H Films to Achieve Superlow
Friction .............................................. 277
17.3.1 General Requirements to Achieve Superlow
Friction with DLC Films ............................... 277
17.3.2 Influence of Hydrogen Content in the Film:
Low Interacting Surfaces ....................... 278
17.3.3 Influence of the Mechanical Behavior of the
Film: Compliant Surfaces ....................... 281
17.4 Achievement and Preservation of Superlow Friction
with a-C:H Films ...................................... 283
17.4.1 How to Achieve Superlow Friction: Tribonlm
Build-Up Controlled by Surface Chemistry of
the Counterface ................................ 283
17.4.2 How to Preserve Superlow Friction:
Tribo-reactivity of the Contact Controlled by
Gaseous Environment ............................ 285
17.5 Conclusion ............................................ 292
References.................................................. 293
18 Suppression of Moisture Sensitivity of Friction in
Carbon-Based Coatings ...................................... 295
C. Freyman, B. Zhao and Y.-W. Chung ........................ 295
18.1 Introduction .......................................... 295
18.2 Synthesis ............................................. 297
18.3 Surface Characterization .............................. 298
18.3.1 Compositional Analysis ......................... 298
18.3.2 Surface Roughness .............................. 301
18.4 Tribological Testing .................................. 302
18.5 Water-Film Interactions ............................... 304
18.6 Mechanical Properties ................................. 306
18.6.1 Hardness and Elastic Modulus ................... 306
18.6.2 Film Stress .................................... 307
18.7 Conclusion ............................................ 309
References ................................................. 309
19 Application of Carbon Based Nano-Materials to Aeronautics
and Space Lubrication ...................................... 311
K.W. Street, Jr. K. Miyoshi and R.L. Vander Wal ............ 311
19.1 Introduction .......................................... 311
19.2 Experimental .......................................... 312
19.2.1 Instrumentation ................................ 312
19.2.2 Sample Preparation ............................. 315
19.2.3 Analytic Techniques and Post Mortem Analysis ... 316
19.3 Results and Discussion ................................ 317
19.3.1 Nano-onion Investigations ...................... 317
19.3.2 Multi-walled Nanotube Investigations ........... 322
19.3.3 Single-walled and Surface Fluorinated
Nanotube Investigations ........................ 332
19.4 Concluding Remarks .................................... 338
References ................................................. 338
20 Superlubricity of CNx-coatings in Nitrogen Gas
Atmosphere ................................................. 341
K. Kato and K. Adachi ...................................... 341
20.1 Introduction .......................................... 341
20.2 Fundamental Properties of CNx-coatings ................ 341
20.2.1 Coating Method ................................. 341
20.2.2 Hardness and Microstructure .................... 343
20.3 Superlubricity of CNx-coating on Si-wafer sliding
against Si3N4 ball .................................... 345
20.3.1 Friction on CNx-coatings in Vacuum After
Short Time Exposure to Air, O2 or N2 ........... 345
20.3.2 Friction on CNx-coatings in Gases of 7.4×104
Pa ............................................. 345
20.4 Superlubricity of CNx-coating on Si3N4 Disk Sliding
against Si3N4 Ball or CNx-coating on Si3N4 Ball ....... 348
20.5 Mechanisms of Low Friction and Low Wear of
CNx-coatings .......................................... 351
20.5.1 The Effect of Humidity in N2 on Friction ....... 355
20.5.2 The Effect of O2 in N2 on Friction ............. 358
20.5.3 The Effect of Surface Roughness on Friction .... 358
20.5.4 Tribolayers of Superlubricity .................. 360
20.6 Summary ............................................... 363
References ................................................. 363
21 Achieving Ultralow Friction by Aqueous, Brush-Assisted
Lubrication ................................................ 365
S. Lee and N.D. Spencer .................................... 365
21.1 Introduction .......................................... 365
21.2 Macroscopic Scale Contacts ............................ 368
21.2.1 Rigid Materials ................................ 368
21.2.2 Soft Materials ................................. 374
21.3 Micro/Nanoscopic Scale Studies ........................ 378
21.3.1 General Aspects ................................ 378
21.3.2 Water-soluble Polymer Brushes .................. 384
21.4 Summary and Outlook ................................... 391
References ................................................. 392
22 Friction Control at the Molecular Level: From
Superlubricity to Stick-Slip ............................... 397
D. Mazuyer, A. Tonck and J. Cayer-Barrioz .................. 397
22.1 Introduction .......................................... 397
22.2 Experimental .......................................... 402
22.2.1 The Molecular Tribometer ....................... 402
22.2.2 The Materials .................................. 403
22.2.3 Experimental Procedure ......................... 405
22.2.4 Properties of the Confined Layer under
Loading ........................................ 406
22.3 Results and Discussion ................................ 409
22.3.1 Squeeze Behavior of the Adsorbed Layer of
the Friction Modifiers ......................... 409
22.3.2 Frictional Properties of the Adsorbed Layers
of Friction Modifiers .......................... 411
22.3.3 Physical Interpretation ........................ 422
References ................................................. 424
23 Super Low Traction under EHD & Mixed Lubrication Regimes ... 427
P. Vergne .................................................. 427
23.1 Introduction .......................................... 427
23.1.1 Superlubricity, Near Frictionless Sliding and
Super Low Traction ............................. 427
23.1.2 Chapter Objectives and Summary ................. 428
23.2 Traction versus Super Low Traction .................... 428
23.2.1 Generalities on EHD Traction ................... 428
23.2.2 Super Low Traction and Experimental Issues ..... 430
23.3 Experimental conditions ............................... 431
23.4 Lubricated Super Low Traction ......................... 432
23.4.1 Newtonian Isothermal Piezoviscous Behavior ..... 432
23.4.2 Shear Thinning ................................. 435
23.4.3 Thin Film EHD Conditions ....................... 436
23.5 Discussion and Conclusion ............................. 440
Acknowledgements ........................................... 442
Annex: Main Properties of the Lubricants ................... 442
References ................................................. 442
24 Superlubricity of In Situ Generated Protective Layer on
Worn Metal Surfaces in Presence of Mg6Si4O10(OH)8 ........... 445
J. Yuansheng and L. Shenghua ............................... 445
24.1 Introduction .......................................... 445
24.2 Tribochemical Principles of In Situ Reconditioning
of Rubbing Metal Surfaces ............................. 446
24.2.1 Tribological Process ........................... 446
24.2.2 Tribochemical Reactions ........................ 447
24.3 Superlubricity of Protective Layer Generated by ART
Mechanochemical Reconditioner Package ................. 450
24.3.1 Protective Layer Generated in Railway
Locomotive Trials .............................. 450
24.3.2 Observation of the Protective Layer on
Cylinder Bore .................................. 451
24.3.3 Nano-hardness .................................. 453
24.3.4 Surface Roughness .............................. 454
24.3.5 Coefficient of Friction ........................ 454
24.3.6 Protective Layer Generated in Laboratory
Conditions ..................................... 455
24.4 Possible Sources of Superlubricity of In Situ
Generated Protective Layer on Worn Metal Surfaces ..... 461
24.4.1 Phase Structure of the Protective Layer ........ 462
24.4.2 Raman Spectrometry Analysis .................... 466
24.4.3 Possible Sources of Superlubricity ............. 466
Acknowledgements ........................................... 467
References ................................................. 467
25 Superlubricity of Diamond/Glycerol Technology Applied to
Automotive Gasoline Engines ................................ 471
M.I. De Barros Bouchet and M. Kano ......................... 471
25.1 Introduction .......................................... 471
25.2 Methods ............................................... 472
25.2.1 DLC Materials Preparation ...................... 472
25.2.2 Tribological Tests ............................. 472
25.2.3 Engine Tests ................................... 474
25.2.4 Nanoscratch Measurement ........................ 475
25.2.5 Mechanical Measurements ........................ 475
25.2.6 Surface Analyses Techniques .................... 475
25.2.7 Microstructural Analysis Technique ............. 476
25.3 Results and Discussion ................................ 477
25.3.1 DLC Materials Characterizations ................ 477
25.3.2 Steel/DLC Tribological Systems Lubricated by
Glycerol Mono-Oleate (GMO) ..................... 481
25.3.3 DLC/DLC Tribological Systems Lubricated by
Glycerol and GMO ................................484
25.3.4 Superlubricity Mechanism as Studied by Surface
Analyses ....................................... 485
25.3.5 Engine Test Results and Application ............ 489
25.4 Conclusion ............................................ 491
Acknowledgements ........................................... 491
References ................................................. 492
Subject Index ................................................. 493
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