Some topics in theoretical nanofriction
Description
As is natural for all properties determined by surfaces and interfaces rather than by bulk, adhesion and friction increase in importance when the objects that come into contact and move relative to one another are nanosized. In this talk I propose to review some theory and simulation work recently done in our group on topics and models that are inspired by nanofriction. Among them are: * Some strange phenomena determined by the sliding of periodic but incommensurate systems. * The effect of high temperatures and surface melting on the friction felt by an AFM tip. * The negative differential friction predicted for high-speed sliding coaxial nanotubes. * The diffusive-ballistic crossover predicted for the frictional slip time of gold nanoclusters on graphite.
| Slides | |
| 0:00 | (NANO)FRICTION SOME THEORETICAL SURPRISES |
| 1:05 | Rferences |
| 1:29 | 1. MOVING MOIRE' PATTERNSAROUND |
| 3:03 | Lubricated Friction |
| 3:42 | Harmonic Chain Among Two Periodic Sliding Substrates[4] |
| 4:26 | The system dynamicsis described by |
| 4:51 | Length ratios: commensurability |
| 5:08 | Lubricant sliding velocity: surprise! |
| 7:07 | Solitions: kinks and anti-kinks |
| 9:29 | Consequences of kinks |
| 9:31 | Animations: kinks |
| 10:14 | Animations: anti-kinks |
| 10:27 | Animations: the Golden Mean |
| 10:34 | MOIRE' PATTERNS: THEY ARE THE REAL OBJECTS THAT CAN BE DRAGGED! |
| 11:19 | 2. NANOFRICTION CLOSE TO THE MELTING TEMPERATURE |
| 11:28 | Animations: the Golden Mean |
| 12:17 | 2. NANOFRICTION CLOSE TO THE MELTING TEMPERATURE |
| 13:06 | FRICTION DROPS AT HIGH TEMPERATURE... |
| 13:37 | ....LIKE IN ICE SKATING. |
| 14:04 | ...BUT FRICTION MAY ALSO DECREASE AT HIGH TEMPERATURE! |
| 14:49 | A POLYCRYSTALLINE SURFACE |
| 14:56 | NANOFRICTION: A (RARE) WELL DEFINED FRICTION EXPERIMENT |
| 15:08 | ON A NORMAL SURFACE YOU'D LOSE YOUR TIP |
| 16:01 | TRY A NONMELTINGSURFACE: |
| 16:18 | THEORY + SIMULATION |
| 16:46 | HIGH TEMPERATURE FRICTION SIMULATIONS |
| 17:02 | HIGH T PLOWING SIMULATIONS |
| 17:04 | HIGH TEMPERATURE FRICTION SIMULATIONS |
| 17:12 | HIGH T PLOWING SIMULATIONS |
| 17:31 | PLOWING FRICTION |
| 18:06 | PLOWING FRICTION: FORCES |
| 18:40 | FRICTIONAL DROP! |
| 19:15 | ....JUST LIKE IN ICE SKATING! |
| 19:20 | TIP CARRIES LIQUID CLOUD, AS IN SKATING |
| 19:40 | PLOWING FRICTION |
| 20:08 | WEARLESS, GRAZING FRICTION (1) |
| 20:16 | FRICTIONAL DROP! |
| 20:56 | WEARLESS, GRAZING FRICTION (1) |
| 21:07 | WEARLESS, GRAZING FRICTION (2) |
| 21:52 | WEARLESS, GRAZING FRICTION (3) |
| 22:40 | ANALOG: IMPURITY PINNING OF THE FLUX LATTICE |
| 23:37 | THE “PEAK EFFECT” IN SUPERCONDUCTORS (1) |
| 24:40 | THE “PEAK EFFECT” IN SUPERCONDUCTORS (2) |
| 24:47 | LINEAR RESPONSE THEORY (1) |
| 25:51 | LINEAR RESPONSE THEORY (2) |
| 26:08 | CONCLUSIONS (1) |
| 26:28 | CONCLUSIONS (2) |
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