Much of this Thematic Series is dedicated to experiments and models dealing with friction, wear and adhesion on the nanoscale, where works ranging from atomic-scale sliding friction as well as manipulation of nano-objects, nanotribology of novel functional materials, boundary lubrication and dissipation mechanisms at finite separations are also presented.
Figure 1: Schematic illustration for the synthesis of N-rGO.
Figure 2: N-rGO dispersion nanolubricant at different concentration.
Figure 3: Schematic of the ball-pot assembly in a four-ball tester.
Figure 4: Coefficient of friction at low N-rGO concentrations.
Figure 5: Coefficient of friction at high N-rGO concentrations.
Figure 6: Variation of COF over time for base oil and nanolubricant with N-rGO (3 mg/L).
Figure 7: Wear scar diameter (WSD) of stainless steel balls lubricated with (a) base oil and (b) N-rGO nanolu...
Figure 8: Comparison of the measured temperature of base oil and N-rGO (3 mg/L) nanolubricant as a function o...
Figure 9: Unit load and current of ID fan A and B for (a) Ch 1, (b) Ch 2 before overhaul (replacement of base...
Figure 10: Power Consumption data for ID Fan A and B for few months.
Figure 1: The schematic of hydrodynamic lubrication in a 1D slider bearing considering the effect of the EDL. ...
Figure 2: Dimensionless electrical potential distribution obtained by solving the linear PBE and the nonlinea...
Figure 3: The effect of the zeta potential on the apparent viscosity of the lubricant based on different assu...
Figure 4: The effect of the zeta potential on the apparent viscosity of the lubricant and the dependence of t...
Figure 5: Comparison of the hydrodynamic load capacity of the lubricant including the effect of the zeta pote...
Figure 6: The effect of zeta potential on the hydrodynamic load capacity of the lubricant and the dependence ...
Figure 1: Representation of the applied cryogenic treatment.
Figure 2: Schematics of the used scratch method to measure friction and wear: (a) pre-scan to get the initial...
Figure 3: SEM image of a) CHT specimen and b) DCT specimen, showing a martenstic matrix with precipitated glo...
Figure 4: Elastic recovery values for nanoindentations performed with a conical indenter (r ≈ 100 µm) at 1000...
Figure 5: a) Evolution of wear coefficient during the tests at 1000 μN of applied normal load and b) cumulati...
Figure 6: Evolution of the relative average roughness after each test cycle.
Figure 7: Evolution of the friction coefficient during the nanowear test.
Figure 8: Scanning probe microscopy (SPM) image after 30 cycles of nanoscratch testing in a DCT specimen. The...
Figure 9: Depth profiles after a wear test in a DCT specimen in the a) longitudinal and b) transversal direct...
Figure 1: Geometrical scheme of the system under investigation. Stamp of a cylindrical shape with radius a0, ...
Figure 2:
(a) Kinetic dependence of the friction force Fx(t), calculated at parameters τmax = 106 Pa, = 1.0, ...
Figure 3: (a) Time dependence of the order parameter φ(t), calculated using the same parameters as in Figure 2 and co...
Figure 4: (a) Time dependence of the friction force Fx (Equation 16) using the parameters of Figure 2 and an increasing temperat...
Figure 5: (a) Dependence of the friction force Fx on the stamp coordinate X (upper friction surface), corresp...
Figure 1: Structure of the studied ILs.
Figure 2: (a) AFM observation of the worn surface of Si submitted to nanotribological tests under dry conditi...
Figure 3: CoF as a function of the Sommerfeld parameter, Z, for (a) humid and (b) dry PEG (black circle) and ...
Figure 4: Contact angles of (a) humid and (b) dry PEG + [BMIM][DCA] (1), PEG + [BMIM][TfO] (2), PEG + [EMIM][...
Figure 5: CoF vs Sommerfeld parameter, Z, for (a) TfO-based, (b) DCA-based and (c) EtSO4-based ILs mixed with...
Figure 6: AFM images and height profiles of the sliding tracks in (a) dry PEG, (b) PEG + [EMIM][TfO] and (c) ...
Figure 7: XPS regions of (a) C 1s, (b) S 2s, and (c) N 1s for, from bottom to top, in (a) Si/PEG, Si/PEG + [E...
Figure 1: Friction coefficient plotted as a function of fluid viscosity and shear velocity divided by load (S...
Figure 2: Schematic of a QCM immersed in aqueous suspensions of −ND and +ND, for sliding friction studies on ...
Figure 3: Representative friction coefficient versus time plots for alumina (left) and stainless steel (right...
Figure 4: Representative AFM images of stainless steel 304 (left) and alumina (right) QCM electrodes after 1 ...
Figure 5: SEM images of SS304 QCM electrodes after oscillated in (a) water, (b) −ND, and (c) +ND suspensions ...
Figure 6: RMS roughness σ versus scan size L for QCM electrodes comprised of alumina (left) and stainless ste...
Figure 7: Time course of changes in mechanical resistance, R (top, open squares), and frequency f (bottom, fi...
Figure 1: A sketch of the 1D slider-substrate model. The large sphere represents the slider, which moves alon...
Figure 2: The potential-energy profile experienced by the slider as it moves along a hypothetical chain with ...
Figure 3: The time dependence (a) and (b) of the slider velocity vSL and (c) of the chain center of mass vCM ...
Figure 4: The dynamical friction force as a function of the damping coefficient γ that fixes the (unphysical)...
Figure 5: Three snapshots of the instantaneous velocities of a few chain atoms as a function of their positio...
Figure 6: Dynamic friction force as a function of the slider speed vSL. For comparison, the horizontal dashed...
Figure 7: (a): A snapshot of the velocities of the chain particles while the slider, instantly at the vertica...
Figure 8: The square modulus of the Fourier transforms of the velocities vj(t), at six subsequent times. Here...
Figure 9: The time-averaged square modulus of the Fourier transform of the chain velocities, for a few charac...
Figure 10:
The positions (a) and heights (b) of the peaks of as functions of vSL. Panels (c) and (d): detail ...
Figure 11:
A direct comparison of the peak wave vectors of , with the dynamic friction Fd as a function of vSL...
Figure 12: A scheme of the steps performed to identify the phonons whose phase velocity equals vSL, and the co...
Figure 13:
The positions of the observed peaks of (symbols), compared with the values of k of the phonons who...
Figure 14: (a): The motion of the slider (solid line) as it is pulled by a spring having elastic constant Kpull...
Figure 15: For smaller and smaller support velocity vpull, the maximum elastic force experienced by the slider...
Figure 1: Three-dimensional geometric model of fluid in a micro-dimple array and a single micro-dimple unit.
Figure 2: The computational domain.
Figure 3: The division of the fluid domain in the micro-dimple unit.
Figure 4: Variations of the dimensionless average film carrying force and the computing time.
Figure 5: The typical meshed model of a micro-dimple unit.
Figure 6: Pressure distribution on the upper wall of the lubricant in the micro-dimple unit.
Figure 7: Pressure distribution of the cross-sectional area of the lubricant in a micro-dimple unit.
Figure 8: The pressure distribution on the upper wall for (a) Re = 5, (b) Re = 50 and (c) Re = 250.
Figure 9: Effect of Reynolds number on the pressure distribution on the middle section of the micro-dimple un...
Figure 10: Effect of texture density and aspect ratio on the dimensionless average film carrying force for (a) ...
Figure 11: Variation of the fluid velocity in the micro-dimple unit with (a) λ = 0.025, (b) λ = 0.075, (c) λ =...
Figure 12: Effect of texture density and aspect ratio on the dimensionless average film shear force for (a) Re...
Figure 13: Effect of texture density and aspect ratio on the friction coefficient for (a) Re = 5, (b) Re = 50 ...
Figure 14: Effect of Reynolds number on (a) the dimensionless average film carrying force, (b) the dimensionle...
Figure 15: Effect of Reynolds number on the optimum texture density and optimum aspect ratio.
Figure 1: Schematic of the wear-induced atomic force microscopy (AFM) experimental protocols using (A) conven...
Figure 2: Atomic force microscopy (AFM) contact mode topographic images of wear tracks resulting from wear ex...
Figure 3: Summary of the steps for computing the wear volume from AFM topographic images (image size: 5 × 5 µ...
Figure 4: A and B (grey scale is 35 nm) are the AFM contact mode topographic images before and after the wear...
Figure 5: Wear volume as a function of the sliding time at a sliding velocity of 880 µm/s and a normal load o...
Figure 6: Wear rate as a function of the applied normal load with a given sliding velocity (880 µm/s) and a 2...
Figure 1: Friction force maps for a) an oxidized Si(100) surface scanned with an intact Ar-sputter cleaned SiO...
Figure 2: Graphs exemplifying the absence of contact ageing for slide–hold–slide experiments under UHV condit...
Figure 3: Development of friction for different tip–surface pairs upon activation of the interface. 1 – Contr...
Figure 4: Lateral force loops of the same line from different scan frames. The respective scan number is indi...
Figure 5: Surface topography of the same area before (upper row) and after (lower row) the friction sequences...
Figure 6: Scanning electron microscopy (SEM) images (secondary electrons (SE), back-scattered electrons (BSE)...
Figure 7: TEM images of a cross section through the apex of a Au/Si tip that had been sliding against Au(111)...
Figure 1: a) Scheme of a MoO3 nanocrystal on MoS2. The AFM tip is firmly positioned on top on the nanocrystal...
Figure 2: a) Example of a nanomanipulation during which half of a nanoparticle is scan-imaged, before the tip...
Figure 3: Dependence of nanoparticle shear stress on the contact area. a) Relative shear stress obtained from...
Figure 4: Front perspective: a snapshot of a MD-simulated frictional interface between a colloidal monolayer ...
Figure 5: a) A graphene nanoribbon manipulated along a Au(111) surface. A probing tip lifts the GNR verticall...
Figure 6: Single-molecule tribology. a) Schematic drawing of the experiment: A single porphyrin molecule is a...
Figure 7: Non-contact friction experiments of NbSe2. At certain voltages and distances, one finds dramaticall...
Figure 8: The “Swiss Nanodragster” (SND), a 4’-(p-tolyl)-2,2’:6’,2”-terpyridine molecule, was moved across an...
Figure 9: Example of a change of conformation potentially triggered at surfaces. a) Trans (1) and cis (2) iso...