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Introduction | |
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Why is it called tribology? | |
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Economic and technological importance of tribology | |
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Some tribology success stories | |
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Reducing automotive friction | |
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MEMS and solving adhesion in Digital Micro-mirror Devices | |
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Slider-disk interfaces in disk drives | |
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A brief history of modern tribology | |
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Scientific advances enabling nanoscale tribology | |
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Breakthrough technologies relying on tribology at the small scale | |
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Nanoimprinting | |
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IBM's millipede for high density storage | |
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Nanotechnology | |
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References | |
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Characterizing surface roughness | |
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Types of surface roughness | |
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Roughness parameters | |
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Variations in Z-height | |
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Asperity summits roughness parameters | |
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Surface height distributions | |
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Measuring surface roughness | |
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Atomic force microscopy (AFM) | |
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Example: Disk surfaces in disk drives | |
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References | |
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Mechanical properties of solids and real area of contact | |
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Atomic origins of deformation | |
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Elastic deformation | |
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Basic relations | |
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Elastic deformation of a single asperity | |
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Approximating a single asperity contact | |
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Elastic contact area for a sphere on a flat | |
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Example: Spherical steel particle sandwiched between two flat surfaces | |
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Plastic deformation | |
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Basic relations | |
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Hardness | |
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Real area of contact | |
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Greenwood and Williamson model | |
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Example: TiN contacts | |
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Real area of contact using the Greenwood and Williamson model | |
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Example: Recording head on a laser textured disk surface | |
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Inelastic impacts | |
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References | |
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Friction | |
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Amontons' and Coulomb's laws of friction | |
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Adhesion and plowing in friction | |
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Adhesive friction | |
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Plowing friction | |
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Work hardening | |
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Junction growth | |
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Static friction | |
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Stick-slip | |
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Velocity-controlled stick-slip | |
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Time-controlled stick-slip | |
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Displacement-controlled stick-slip | |
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References | |
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Surface energy and capillary pressure | |
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Liquid surface tension | |
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Capillary pressure | |
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Capillary pressure in confined places | |
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The Kelvin equation and capillary condensation | |
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Example: Capillary condensation of water in a nanosized pore | |
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Example: Capillary condensation of an organic vapor at a sphere-on-flat geometry | |
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Interfacial energy and work of adhesion | |
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Surface Energy of Solids | |
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Why solids are not like liquids | |
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Experimental determination of a solid's surface energy | |
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Contact angles | |
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Estimating interfacial energies | |
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Zisman method for estimating surface energy for a solid | |
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Types of wetting | |
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Contact angle measurements | |
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Contact angle hysteresis | |
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Adhesion hysteresis | |
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References | |
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Surface forces derived from surface energies | |
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The Derjaguin approximation | |
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Dry environment | |
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Force between a sphere and a flat | |
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Example: Adhesion force between two polystyrene spheres | |
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Example: Adhesion force between a polystyrene sphere and a PTFE Flat | |
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Example: Adhesion force for an atomically sharp asperity | |
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Adhesion-induced deformation at a sphere-on-flat contact | |
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The Johnson-Kendall-Roberts (JKR) theory | |
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The Derjaguin-Muller-Toporov (DMT) theory | |
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Adhesion deformation in nanoscale contacts | |
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Wet environment | |
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Force for a sphere-on-flat in a wet environment | |
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Example: Lubricant meniscus force on an AFM tip | |
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Solid-solid adhesion in the presence of a liquid meniscus | |
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Water menisci in sand | |
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Meniscus force for different wetting regimes at contacting interfaces | |
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Toe dipping regime | |
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Example: Toe dipping adhesion with exponential distribution of summit heights | |
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Pillbox and flooded regimes | |
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Immersed regime | |
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Example: Liquid adhesion of a microfabricated cantilever beam | |
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References | |
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Physical origins of surface forces | |
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Normal force sign convention | |
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Repulsive atomic potentials | |
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Van der Waals forces | |
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Van der Waals forces between molecules | |
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Retardation effects for dispersion forces | |
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Van der Waals forces between macroscopic objects | |
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Molecule-flat surface interaction | |
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Flat-Flat interaction | |
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Sphere-flat interaction | |
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The Hamaker constant | |
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Determining Hamaker constants from Lifshitz's theory | |
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Example: Van der Waals force on a polystyrene sphere above a Teflon flat | |
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Surface energies arising from van der Waals interactions | |
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Van der Waals adhesive pressure | |
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Van der Waals interaction between contacting rough surfaces | |
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Example: Stuck microcantilevers | |
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Example: Gecko adhesion | |
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Van der Waals contribution to the disjoining pressure of a liquid film | |
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Liquid-mediated forces between solids | |
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Solvation forces | |
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Example: Squalane between smooth mica surfaces | |
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Oscillatory solvation forces at sharp AFM contacts | |
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Forces in aqueous medium | |
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Electrostatic double-layer force | |
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Hydration repulsion and hydrophobic attraction | |
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Contact electrification | |
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Mechanisms of contact electrification | |
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Conductor-conductor contact | |
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Example: Recording head slider flying over a disk in a disk drive | |
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Metal-insulator and insulator-insulator Contacts | |
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AFM studies of contact electrification | |
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References | |
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Measuring surface forces | |
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Surface force apparatus | |
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Atomic force microscope | |
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Examples of forces acting on AFM tips | |
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Van der Waals forces under vacuum conditions | |
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Capillary condensation of contaminants and water vapor | |
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Bonded and unbonded perfluoropolyether polymer films | |
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Electrostatic double-layer force | |
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References | |
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Lubrication | |
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Lubrication regimes | |
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Viscosity | |
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Definition and units | |
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Non-Newtonian behavior and shear degradation | |
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Temperature dependence | |
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Fluid film flow in confined geometries | |
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Slippage at liquid-solid interfaces | |
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Definition of slip length | |
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Measuring slip at liquid-solid interfaces | |
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Pressure drop versus flow rate method | |
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Drainage versus viscous force | |
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Mechanisms for slip at liquid-solid interfaces | |
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Molecular slip | |
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Molecular slip at low energy surfaces | |
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Slippage of polymers melts | |
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Apparent slip | |
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Example: Shear stress in the presence of slip | |
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Why does the no-slip boundary condition work so well? | |
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Fluid film lubrication | |
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Hydrodynamic lubrication | |
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Inclined plane bearing | |
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Rayleigh step bearing | |
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Journal bearings | |
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Gas bearings | |
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Slip flow in gas bearings | |
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Elastohydrodynamic lubrication | |
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Pressure dependence of viscosity | |
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Pressure-induced elastic deformation | |
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Example: Minimum film thickness between sliding gear teeth | |
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Experimental measurements of elastohydrodynamic lubrication | |
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Important physical and chemical properties of lubricants | |
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Surface tension | |
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Thermal properties | |
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References | |
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Lubrication in tight spots | |
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Confined liquids | |
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Boundary lubrication | |
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Molecular mechanisms of boundary lubrication | |
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Molecularly thin liquid boundary lubricant layers | |
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Example of the importance of end-groups in a liquid lubricant film | |
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Capillary and disjoining pressures | |
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Disjoining pressure | |
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Distribution of a liquid film around a pore opening | |
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Example: Measurement of the disjoining pressure of a perfluoropolyether lubricant | |
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Lubricant distribution between contacting surfaces | |
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Meniscus force | |
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Example: Stiction of a recording head slider | |
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Calculating meniscus force | |
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Example: Calculation of stiction force of disk drive sliders in the pillbox regime | |
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Padded or stiction-free slider | |
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Liquid menisci at high speeds | |
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References | |
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Atomistic origins of friction | |
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Simple models for adhesive friction | |
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Atomistic models for static friction | |
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Frenkel-Kontorova model | |
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Experimental realizations of ultra-low friction in incommensurate sliding systems | |
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Tomlinson model | |
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Example: An AFM tip sliding across an NaCl crystal at ultra-low loads | |
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Molecular dynamic simulations | |
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Example: Cold welding | |
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Why static friction occurs in real-life situations | |
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Atomic origins of kinetic friction | |
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Sliding isolated molecules and monolayers across surfaces | |
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Quartz crystal microbalance | |
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Example: Xe on Ag(111) | |
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Movement of a liquid film on a surface with the blow-off technique | |
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Example: Wind-driven flow of perfluoropolyether lubricants on silicon wafers | |
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Pinning of an absorbed layer | |
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References | |
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Wear | |
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Simple model for sliding wear | |
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Major influences on wear rates | |
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Wear maps | |
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Mechanisms of wear | |
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Wear from plastic deformation | |
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Adhesive wear | |
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Example: An atomic level simulation of adhesive wear | |
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Abrasive wear | |
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Oxidative wear | |
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Metals | |
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Carbon overcoats | |
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Ceramics | |
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Plasticity at the nanoscale | |
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References | |
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Index | |