Moisture-induced ageing in granular media and the kinetics of capillary condensation

Bocquet, Lydéric; Charlaix, Élisabeth; Ciliberto, S.; Crassous, Jérôme

doi:10.1038/25492

Cited by 384 publications

(402 citation statements)

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“…It is, however, contrary to what Bocquet et al [127] and Riedo et al [128] assumed to describe the influence of humidity on friction. Their time scale for formation and breakage of nanocontacts is, however, much faster.…”

Section: Meniscus Forcecontrasting

confidence: 52%

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On the Adhesion between Fine Particles and Nanocontacts: An Atomic Force Microscope Study

et al. 2006

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To optimize the handling of fine powders in industrial applications, understanding the interaction forces between single powder particles is fundamental. The forces between colloidal particles dominate the behavior of a great variety of materials, including paints, paper, soil, and many industrial processes. With the invention of the atomic force microscope (AFM), the direct measurement of the interaction between single micron-sized particles became possible. The adhesional contact between a particle and a substrate is a parameter for analyzing pull-off force data generated by AFM. The aim of this study was to understand surface interactions between fine particles. I measured the adhesion forces between AFM tips or particles attached to AFM cantilevers and different solid samples. Smooth and homogeneous surfaces such as silicon wafer, mica, or highly oriented pyrolytic graphite (HOPG), and more rough and heterogeneous surfaces such as iron particles or patterns of TiO 2 nanoparticles on silicon wafer were used. First, I addressed to the wellknown issue that AFM adhesion experiment results show wide distributions of adhesion forces rather than a single value. My experimental results show that variations in adhesion forces comprise fast (i.e., from one force curves to the next) random fluctuations and slower fluctuations, which occur over tens or hundreds of consecutive measurements. Slow fluctuations are not likely to be the result of variations in external factors such as lateral position, temperature, humidity, and so forth because those were kept constant. Even if two solid bodies are brought into contact under precisely the same conditions (same place, load, direction, etc.) the result of such a measurement will often not be the same as for the previous contact. The measurement itself will induce structural changes in the contact region which can change the value for the next adhesion force measurement.In the second part I studied the influence of humidity on the adhesion of nanocontacts. Humidity was adjusted relatively fast to minimize tip wear during one experiment. For hydrophobic surfaces, no signification change of adhesion force with humidity was observed. Adhesion force-versus-humidity curves recorded with hydrophilic surfaces either showed a maximum or continuously increased. I demonstrate that the results can be interpreted with simple continuum theory of the meniscus force. The meniscus force is calculated based on a model that includes surface roughness and takes into account different AFM tip (or particle) shapes by a two-sphere-model.Experimental and theoretical results show that the precise contact geometry has a critical influence on the humidity dependence of the adhesion force.Changes of tip geometry on the sub-10-nm length scale can completely change adhesion force-versus-humidity curves. Our model can also explain the differences between earlier AFM studies, where different dependencies of the adhesion force on humidity were observed.Keywords: Atomic force microscopy (AFM), cantile...

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Section: Meniscus Forcecontrasting

confidence: 52%

“…To describe this mathematically roughness was modeled by a single spherical asperity [39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

On the Adhesion between Fine Particles and Nanocontacts: An Atomic Force Microscope Study

et al. 2006

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“…If the contact time is below a critical value, it has been observed that F c increases with increasing contact times. 16,17 Another assumption in eq 1 is that the surfaces in contact are perfectly smooth, and of course this is not always the case for real surfaces. Recent investigations have demonstrated that the surface roughness plays a crucial role in the humidity and time dependence of capillary forces.…”

Section: Introductionmentioning

confidence: 99%

“…Recent investigations have demonstrated that the surface roughness plays a crucial role in the humidity and time dependence of capillary forces. [16][17][18][19] These studies show that many capillaries can form between the asperities of two surfaces in contact, and this leads to an increase of F c with increasing contact time and humidity. Finally, in eq 1 F c does not depend on the normal load, whereas recent studies have shown that for rough surfaces the adhesion forces can depend on the normal load if there are plastic deformations of the asperities in the contact.…”

Section: Introductionmentioning

confidence: 99%

“…However, it may take a long time to reach the equilibrium state, since the formation of a water bridge is a thermally activated process. 16,17,20 The energy barrier for the formation of bridges of height h and cross section R c 2 is ∆E(h) ) k B T ln(P S /P)hR c 2 /V M . By considering the thermally activated capillary condensation between two rough surfaces sliding one on the other, two important effects have been observed.…”

Section: Introductionmentioning

confidence: 99%

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The ²/₃ Power Law Dependence of Capillary Force on Normal Load in Nanoscopic Friction

et al. 2004

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During the sliding of an atomic force microscope (AFM) tip on a rough hydrophilic surface, water capillary bridges form between the tip and the asperities of the sample surface. These water bridges give rise to capillary and friction forces. We show that the capillary force increases with the normal load following a 2 / 3 power law. We trace back this behavior to the load induced change of the tip-surface contact area which determines the number of asperities where the bridges can form. An analytical relationship is derived which fully explains the observed interplay between humidity, velocity, and normal load in nanoscopic friction.

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Physicochemical processes of frictional healing: Effects of water on stick‐slip stress drop and friction of granular fault gouge

2014

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Understanding the micromechanical processes that dictate the evolution of fault strength during the seismic cycle is a fundamental problem in earthquake physics. We report on laboratory experiments that investigate the role of water during repetitive stick-slip frictional sliding, with particular emphasis on the grain-scale and atomic-scale mechanisms of frictional restrengthening (healing). Our experiments are designed to test underlying concepts of rate and state friction laws. We sheared layers of soda-lime glass beads in a double direct shear configuration at a constant normal stress of 5 MPa. Shear stress was applied via a constant displacement rate from 0.3 to 300 μm/s. During each experiment, relative air humidity (RH) was kept constant at values of 5, 50, or 100%. Our data show a systematic increase in maximum friction (μ max ), stick-slip friction drop (Δμ), and frictional healing rate, with increasing RH. The highest values of interevent dilation occur at 100% RH. Postexperiment scanning electron microscope observations reveal details of contact junction processes, showing a larger grain-to-grain contact area at higher RH. We find that the evolution of contact area depends inversely on slip velocity and directly on RH. Our results illuminate the fundamental processes that dictate stick-slip frictional sliding and provide important constraints on the mechanisms of rate and state friction.

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Moisture-induced ageing in granular media and the kinetics of capillary condensation

Cited by 384 publications

References 12 publications

On the Adhesion between Fine Particles and Nanocontacts: An Atomic Force Microscope Study

On the Adhesion between Fine Particles and Nanocontacts: An Atomic Force Microscope Study

The ²/₃ Power Law Dependence of Capillary Force on Normal Load in Nanoscopic Friction

Physicochemical processes of frictional healing: Effects of water on stick‐slip stress drop and friction of granular fault gouge

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Moisture-induced ageing in granular media and the kinetics of capillary condensation

Cited by 384 publications

References 12 publications

On the Adhesion between Fine Particles and Nanocontacts: An Atomic Force Microscope Study

On the Adhesion between Fine Particles and Nanocontacts: An Atomic Force Microscope Study

The 2/3 Power Law Dependence of Capillary Force on Normal Load in Nanoscopic Friction

Physicochemical processes of frictional healing: Effects of water on stick‐slip stress drop and friction of granular fault gouge

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The ²/₃ Power Law Dependence of Capillary Force on Normal Load in Nanoscopic Friction