Tribology on the Small Scale A Bottom Up Approach to Friction, Lubrication, and Wear

by Mate, C. Mathew

• ISBN13: 9780198526780
• ISBN10: 0198526784
• Format: Hardcover
• Copyright: 2008-03-01
• Publisher: Oxford University Press

Summary

Friction, lubrication, adhesion, and wear are prevalent physical phenomena in everyday life and in many key technologies. This book explains how these tribological phenomena originate from atomistic and microscale physical phenomena and shows how this understanding can be used to solvemacroscale tribology problems. The book is intended to serve both as a textbook for advanced undergraduate and graduate courses in tribology and as an introduction to the field for those scientists and engineers working with technologies where a good grasp of tribology is essential.

Author Biography

Dr C. Mathew Mate
Hitachi San Jose Research Center, California
Mathew Mate received his Bachelor's in Engineering Science from the University of California at Berkeley in 1981 and his Ph.D. in Physics from the same university in 1986. He joined the IBM Almaden Research Center as a postdoc in 1986 and became a permanent member of the research staff in 1988. In 2003, Mathew became part of the Research Center of Hitachi Global Storage Technologies when IBM sold its disk drive business to Hitachi. While working at IBM and Hitachi, he has become one of the pioneers of elucidating how friction and lubrication occur at the atomic and molecular level and applying this knowledge to practical technology problems such as disk drive reliability. In 2001, he was awarded the MRS Medal from the Materials Research Society in recognition of his pioneering studies of friction at the atomic and molecular level.

Table of Contents

Introduction	p. 1
Why is it called tribology?	p. 2
Economic and technological importance of tribology	p. 3
Some tribology success stories	p. 4
Reducing automotive friction	p. 4
MEMS and solving adhesion in Digital Micro-mirror Devices	p. 5
Slider-disk interfaces in disk drives	p. 7
A brief history of modern tribology	p. 10
Scientific advances enabling nanoscale tribology	p. 12
Breakthrough technologies relying on tribology at the small scale	p. 14
Nanoimprinting	p. 16
IBM's millipede for high density storage	p. 18
Nanotechnology	p. 19
References	p. 20
Characterizing surface roughness	p. 24
Types of surface roughness	p. 24
Roughness parameters	p. 26
Variations in Z-height	p. 26
Asperity summits roughness parameters	p. 28
Surface height distributions	p. 29
Measuring surface roughness	p. 30
Atomic force microscopy (AFM)	p. 30
Example: Disk surfaces in disk drives	p. 33
References	p. 37
Mechanical properties of solids and real area of contact	p. 39
Atomic origins of deformation	p. 39
Elastic deformation	p. 43
Basic relations	p. 43
Elastic deformation of a single asperity	p. 44
Approximating a single asperity contact	p. 44
Elastic contact area for a sphere on a flat	p. 45
Example: Spherical steel particle sandwiched between two flat surfaces	p. 46
Plastic deformation	p. 48
Basic relations	p. 48
Hardness	p. 49
Real area of contact	p. 50
Greenwood and Williamson model	p. 51
Example: TiN contacts	p. 53
Real area of contact using the Greenwood and Williamson model	p. 54
Example: Recording head on a laser textured disk surface	p. 55
Inelastic impacts	p. 59
References	p. 61
Friction	p. 63
Amontons' and Coulomb's laws of friction	p. 63
Adhesion and plowing in friction	p. 66
Adhesive friction	p. 66
Plowing friction	p. 68
Work hardening	p. 70
Junction growth	p. 70
Static friction	p. 72
Stick-slip	p. 74
Velocity-controlled stick-slip	p. 75
Time-controlled stick-slip	p. 77
Displacement-controlled stick-slip	p. 78
References	p. 81
Surface energy and capillary pressure	p. 82
Liquid surface tension	p. 82
Capillary pressure	p. 85
Capillary pressure in confined places	p. 87
The Kelvin equation and capillary condensation	p. 90
Example: Capillary condensation of water in a nanosized pore	p. 91
Example: Capillary condensation of an organic vapor at a sphere-on-flat geometry	p. 91
Interfacial energy and work of adhesion	p. 92
Surface Energy of Solids	p. 93
Why solids are not like liquids	p. 93
Experimental determination of a solid's surface energy	p. 95
Contact angles	p. 96
Estimating interfacial energies	p. 97
Zisman method for estimating surface energy for a solid	p. 98
Types of wetting	p. 101
Contact angle measurements	p. 101
Contact angle hysteresis	p. 103
Adhesion hysteresis	p. 104
References	p. 110
Surface forces derived from surface energies	p. 113
The Derjaguin approximation	p. 113
Dry environment	p. 114
Force between a sphere and a flat	p. 114
Example: Adhesion force between two polystyrene spheres	p. 115
Example: Adhesion force between a polystyrene sphere and a PTFE Flat	p. 115
Example: Adhesion force for an atomically sharp asperity	p. 116
Adhesion-induced deformation at a sphere-on-flat contact	p. 117
The Johnson-Kendall-Roberts (JKR) theory	p. 117
The Derjaguin-Muller-Toporov (DMT) theory	p. 121
Adhesion deformation in nanoscale contacts	p. 121
Wet environment	p. 122
Force for a sphere-on-flat in a wet environment	p. 122
Example: Lubricant meniscus force on an AFM tip	p. 123
Solid-solid adhesion in the presence of a liquid meniscus	p. 125
Water menisci in sand	p. 126
Meniscus force for different wetting regimes at contacting interfaces	p. 128
Toe dipping regime	p. 128
Example: Toe dipping adhesion with exponential distribution of summit heights	p. 129
Pillbox and flooded regimes	p. 131
Immersed regime	p. 132
Example: Liquid adhesion of a microfabricated cantilever beam	p. 133
References	p. 135
Physical origins of surface forces	p. 137
Normal force sign convention	p. 137
Repulsive atomic potentials	p. 138
Van der Waals forces	p. 139
Van der Waals forces between molecules	p. 139
Retardation effects for dispersion forces	p. 142
Van der Waals forces between macroscopic objects	p. 142
Molecule-flat surface interaction	p. 142
Flat-Flat interaction	p. 144
Sphere-flat interaction	p. 145
The Hamaker constant	p. 145
Determining Hamaker constants from Lifshitz's theory	p. 146
Example: Van der Waals force on a polystyrene sphere above a Teflon flat	p. 151
Surface energies arising from van der Waals interactions	p. 152
Van der Waals adhesive pressure	p. 153
Van der Waals interaction between contacting rough surfaces	p. 154
Example: Stuck microcantilevers	p. 156
Example: Gecko adhesion	p. 158
Van der Waals contribution to the disjoining pressure of a liquid film	p. 160
Liquid-mediated forces between solids	p. 162
Solvation forces	p. 162
Example: Squalane between smooth mica surfaces	p. 164
Oscillatory solvation forces at sharp AFM contacts	p. 166
Forces in aqueous medium	p. 167
Electrostatic double-layer force	p. 167
Hydration repulsion and hydrophobic attraction	p. 169
Contact electrification	p. 171
Mechanisms of contact electrification	p. 172
Conductor-conductor contact	p. 172
Example: Recording head slider flying over a disk in a disk drive	p. 175
Metal-insulator and insulator-insulator Contacts	p. 177
AFM studies of contact electrification	p. 179
References	p. 181
Measuring surface forces	p. 186
Surface force apparatus	p. 188
Atomic force microscope	p. 192
Examples of forces acting on AFM tips	p. 195
Van der Waals forces under vacuum conditions	p. 195
Capillary condensation of contaminants and water vapor	p. 197
Bonded and unbonded perfluoropolyether polymer films	p. 200
Electrostatic double-layer force	p. 202
References	p. 204
Lubrication	p. 207
Lubrication regimes	p. 207
Viscosity	p. 209
Definition and units	p. 209
Non-Newtonian behavior and shear degradation	p. 211
Temperature dependence	p. 214
Fluid film flow in confined geometries	p. 214
Slippage at liquid-solid interfaces	p. 216
Definition of slip length	p. 217
Measuring slip at liquid-solid interfaces	p. 218
Pressure drop versus flow rate method	p. 218
Drainage versus viscous force	p. 219
Mechanisms for slip at liquid-solid interfaces	p. 220
Molecular slip	p. 220
Molecular slip at low energy surfaces	p. 220
Slippage of polymers melts	p. 222
Apparent slip	p. 222
Example: Shear stress in the presence of slip	p. 225
Why does the no-slip boundary condition work so well?	p. 225
Fluid film lubrication	p. 226
Hydrodynamic lubrication	p. 228
Inclined plane bearing	p. 229
Rayleigh step bearing	p. 229
Journal bearings	p. 230
Gas bearings	p. 232
Slip flow in gas bearings	p. 234
Elastohydrodynamic lubrication	p. 235
Pressure dependence of viscosity	p. 235
Pressure-induced elastic deformation	p. 236
Example: Minimum film thickness between sliding gear teeth	p. 238
Experimental measurements of elastohydrodynamic lubrication	p. 239
Important physical and chemical properties of lubricants	p. 241
Surface tension	p. 241
Thermal properties	p. 242
References	p. 243
Lubrication in tight spots	p. 246
Confined liquids	p. 246
Boundary lubrication	p. 255
Molecular mechanisms of boundary lubrication	p. 256
Molecularly thin liquid boundary lubricant layers	p. 260
Example of the importance of end-groups in a liquid lubricant film	p. 262
Capillary and disjoining pressures	p. 265
Disjoining pressure	p. 265
Distribution of a liquid film around a pore opening	p. 267
Example: Measurement of the disjoining pressure of a perfluoropolyether lubricant	p. 269
Lubricant distribution between contacting surfaces	p. 270
Meniscus force	p. 272
Example: Stiction of a recording head slider	p. 272
Calculating meniscus force	p. 273
Example: Calculation of stiction force of disk drive sliders in the pillbox regime	p. 275
Padded or stiction-free slider	p. 276
Liquid menisci at high speeds	p. 278
References	p. 279
Atomistic origins of friction	p. 284
Simple models for adhesive friction	p. 284
Atomistic models for static friction	p. 286
Frenkel-Kontorova model	p. 287
Experimental realizations of ultra-low friction in incommensurate sliding systems	p. 289
Tomlinson model	p. 290
Example: An AFM tip sliding across an NaCl crystal at ultra-low loads	p. 291
Molecular dynamic simulations	p. 295
Example: Cold welding	p. 295
Why static friction occurs in real-life situations	p. 295
Atomic origins of kinetic friction	p. 297
Sliding isolated molecules and monolayers across surfaces	p. 297
Quartz crystal microbalance	p. 299
Example: Xe on Ag(111)	p. 300
Movement of a liquid film on a surface with the blow-off technique	p. 301
Example: Wind-driven flow of perfluoropolyether lubricants on silicon wafers	p. 302
Pinning of an absorbed layer	p. 307
References	p. 308
Wear	p. 313
Simple model for sliding wear	p. 314
Major influences on wear rates	p. 317
Wear maps	p. 318
Mechanisms of wear	p. 319
Wear from plastic deformation	p. 319
Adhesive wear	p. 320
Example: An atomic level simulation of adhesive wear	p. 321
Abrasive wear	p. 321
Oxidative wear	p. 325
Metals	p. 325
Carbon overcoats	p. 326
Ceramics	p. 326
Plasticity at the nanoscale	p. 327
References	p. 329
Index	p. 331
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