Sustained Frictional Instabilities on Nanodomed Surfaces: Stick–Slip Amplitude Coefficient

Abstract

Understanding the frictional properties of nanostructured surfaces is important due to their increasing application in modern miniaturised devices. In this work, lateral force microscopy was used to study the frictional properties between an AFM nanotip and surfaces bearing well-de ned nanodomes comprising densely packed prolate spheroids, of diameters ranging from tens to hundreds of nanometres. Our results show that the average lateral force varied linearly with applied load, as described by Amontons' rst law of friction, although no direct correlation between the sample topographic * To whom correspondence should be addressed † 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 properties and their measured friction coe cients was identi ed. Furthermore, all the nanodomed textures exhibited pronounced oscillations in the shear traces, similar to the classic stick-slip behaviour, under all the shear velocities and load regimes studied. School of Chemistry, University of BristolThat is, the nanotextured topography led to sustained frictional instabilities, e ectively with no contact frictional sliding. The amplitude of the stick-slip oscillations, σ f , was found to correlate with the topographic properties of the surfaces, and scale linearly with the applied load. In line with the friction coe cient, we de ne the slope of this linear plot as the stick-slip amplitude coe cient (SSAC ). We suggest that such stick-slip behaviours are characteristics of surfaces with nanotextures, and that such local frictional instabilities have important implications to surface damage and wear.We thus propose that the shear characteristics of the nanodomed surfaces can not be fully described by the framework of Amontons' laws of friction, and that additional parameters (e.g. σ f and SSAC) are required, when their friction, lubrication and wear properties are important considerations in related nanodevices.

Natural and bioinspired nanostructured bactericidal surfaces

“…Surfaces bearing well-defined nanotextures have been increasingly found in modern applications to facilitate enhanced functionalities and desired properties [24], [27], [29]. Due to the ease of fabrication and distinct electronic, optical, mechanical and thermal properties, silicon is widely used in industrial applications.…”

“…Killing bacteria physically though nanostructures rather than chemical means has since become very topical, and several recent reviews on antimicrobial surfaces have focused on different types of antimicrobial coatings to prevent infections [14], [15], use of nanoparticles as antimicrobial agents [16], antimicrobial surfaces based on polymers [17] and other smart materials [18], [19], [20], [21], and naturally occurring antimicrobial surfaces [22], [23]. More generally, nanoparticle dispersions (nanofluids) [24], [25], [26] and nanostructured surfaces are increasingly found in modern formulations and technological applications for controlled adhesion or friction [27], [28], [29] and for enhanced or additional performance and functionalities [30]. Furthermore, the knowledge of nanostructure-bacteria interactions is also intimately related to the topic of nanotoxicity [31] and to our fundamental understanding of interactions between nanoparticles and organised soft matter [32], [33], [34].…”

Frictional properties of self-adaptive chromium doped tungsten–sulfur–carbon coatings at nanoscale

“…As the shape and the radii of the three tips before and after experiments remains similar, the deviation of m parameter from 2/3 power law should be related to different area-load dependence for the tip in contact with Cr-doped coatings as a consequence of their different surface microstructure. Recently it has been shown, that surface geometry, and not the roughness amplitude, influenced the measured friction with AFM [36,37].…”

Probing the nanofriction of non-halogenated phosphonium-based ionic liquid additives in glycol ether oil on titanium surface

“…We observed in Fig. 5 that the line describing the linear friction-load relation does not extrapolate back to the origin but toward F0 as FN = 0, where F0 is the friction at zero load attributed to the contribution of the adhesion force [54][55][56]. This adhesion is mainly from van der Waals, electrostatic, and capillary forces [57].…”