Function Of Normal Load Research Articles

Multiscale Parametrization Of a Friction Model For Metal Cutting Using Contact Mechanics, Atomistic Simulations, And Experiments

In this study, we developed and parametrized a friction model for finite element (FE) cutting simulations of AISI4140 steel, combining experimental data and numerical simulations at various scales. Given the severe thermomechanical loads during cutting, parametrization of friction models based on analogous experiments has been proven difficult, such that the cutting process itself is often used for calibration. Instead, our model is based on the real area of contact between rough surfaces and the stress required to shear adhesive micro contacts. We utilized microtextured cutting tools and their negative imprint on chips to orient chip and tool surfaces, enabling the determination of a combined surface roughness. This effective roughness was then applied in contact mechanics calculations using a penetration hardness model informed by indentation hardness measurements. Consistent with Bowden and Tabor theory, we observed that the fractional contact area increased linearly with the applied normal load, and the effective roughness remained insensitive to cutting fluid application. Additionally, we calculated the required shear stress as a function of normal load using DFT-based molecular dynamics simulations for a tribofilm formed at the interface, with its composition inferred from ex-situ XPS depth profiling of the cutting tools. Our friction model demonstrated good agreement with experimental results in two-dimensional FE chip forming simulations of orthogonal cutting processes, evaluated by means of cutting force, passive force, and contact length prediction. This work presents a proof of concept for a physics-based approach to calibrate constitutive models in metal cutting, potentially advancing the use of multiscale and multiphysical simulations in machining.Graphical abstract

Atomic-Scale Friction Study: Underpotential Deposition (UPD) of Silver on I-Modified Au(111) in Aprotic Electrolyte

Friction in general is one of the main sources of energy loss, and therefore finding ways for better controlling friction is of uttermost importance. Atomic-scale friction is measured using electrochemical lateral force microscopy (EC-LFM) where the AFM tip slides on the surface of electrode under electrochemical control. It helps us to understand interfacial and tribological behavior on nanoscale. In ionic liquids (ILs) including solvate ILs, the friction as function of normal load has been studied on HOPG and Au(111), which shows that the structure of ions is a decisive factor for the friction behavior [1-4]. Our interest was focused on the adsorption of foreign metals, ranging from (sub)monolayer (underpotential deposition (UPD)) to multilayer (bulk) deposition and the adsorption of organic adsorbates, and its influence on friction as function of potential on single crystal electrodes in aqueous electrolyte[5-7].The underpotential deposition (UPD) of silver had often been studied on gold in aqueous electrolyte since the lattice constants of silver and gold are fairly identical (Å, Å) [8-12]. Previous results clearly show that the Ag UPD process is very sensitive to the presence of other adsorbates (e.g. SO4 2-, ClO4 -). Especially, the Ag UPD on iodine covered surface of Au(111) shows completely different atomic structures after the 1st, 2nd, and 3rd Ag UPD compared to the results on Au(111) [9, 13].In this study, we investigate the interfacial properties on I-modified Au(111) during the Ag UPD in aprotic electrolyte. We observed two sets of Ag UPD peaks in cyclic voltammetry (CV). The charge density for these peaks is about 216 µC/cm² close to the theoretical charge density for the monolayer (222 µC/cm²). We observed the iodine structure at low normal load (FN < 20nN), which shows that the iodine adlayer on Au(111) and Ag monolayer forms a (˅3×˅3)R30°. It indicates that the iodine adlayer is stable during the Ag UPD. At high normal load, the AFM tip penetrates into iodine layer and reveals the structure of Au(111) or Ag monolayer depending on the potential. It is remarkable that there is no irreversible wear during the penetration of AFM tip meaning that the iodine structure appears again with decreasing normal loads. At high normal load where the tip penetrates into iodine layer and interacts with substrates (Au and Ag), the friction on Ag monolayer is higher than on Au(111). Interestingly, even though the cyclic voltammetry (CV) shows that the amount of water in the electrolyte has minor influence, the friction increases with an increase in water content on the I/Ag/Au(111).[1] H. Li, M.W. Rutland, R. Atkin, Physical Chemistry Chemical Physics 15 (2013) 14616-14623.[2] H. Li, M.W. Rutland, M. Watanabe, R. Atkin, Faraday discussions 199 (2017) 311-322.[3] O.Y. Fajardo, F. Bresme, A.A. Kornyshev, M. Urbakh, Scientific Reports 5 (2015) 6.[4] A. Elbourne, J. Sweeney, G.B. Webber, E.J. Wanless, G.G. Warr, M.W. Rutland, R. Atkin, Chem. Commun. 49 (2013) 6797-6799.[5] S. Iqbal, S. Wezisla, N. Podgaynyy, H. Baltruschat, Electrochimica Acta 186 (2015) 427-435.[6] M. Nielinger, H. Baltruschat, Physical Chemistry Chemical Physics 9 (2007) 3965-3969.[7] N. Podgaynyy, S. Iqbal, H. Baltruschat, Surface Science 631 (2015) 67-72.[8] T. Hachiya, K. Itaya, Ultramicroscopy 42 (1992) 445-452.[9] K. Ogaki, K. Itaya, Electrochimica acta 40 (1995) 1249-1257.[10] M. Espladiu, M. Schneeweiss, D. Kolb, Physical Chemistry Chemical Physics 1 (1999) 4847-4854.[11] C.H. Chen, S.M. Vesecky, A.A. Gewirth, Journal of the American Chemical Society 114 (1992) 451-458.[12] P. Mrozek, Y.-e. Sung, M. Han, M. Gamboa-Aldeco, A. Wieckowski, C.-h. Chen, A.A. Gewirth, Electrochimica acta 40 (1995) 17-28.[13] S. Sugita, T. Abe, K. Itaya, The Journal of Physical Chemistry 97 (1993) 8780-8785.

Friction on I‐Modified Au(111) in a Tetraglyme Electrolyte

AbstractIn situ electrochemical lateral force microscopy (EC‐LFM) has been employed to study the ordered structure of Li+ containing tetraglyme (G4) in front of I‐modified Au(111) and its influence on friction as function of normal load. Since the effect of water in aprotic electrolytes is a critical issue, the influence of water on the ordered structure and friction was also been investigated. Lateral force maps recorded at low normal load (FN&lt;30 nN) show that the adsorbed iodine forms a structure ( independent of potential. With increasing normal load, observed atomic corrugations at both potentials (0.45 V and −0.4 V) are in agreement with the Au(111) ( structure while returning to a structure with decreasing normal load. Thus we conclude that the AFM tip penetrates into the iodine adlayer without irreversible wear. Astonishingly, no clear friction increase was observed upon penetration into the iodine adlayer; also no corresponding step was found in force separation (FS) curves. On the other hand, FS curves for I‐modified Au(111) in pure G4 solvent and Li+ containing electrolyte clearly showed several steps suggesting that G4 molecules are forming up to five ordered layers. It is noteworthy that we observed two different push‐through forces for the innermost layers. Considering the higher reproducibility of FS curves on I‐modified Au(111) compared to bare Au(111) we assume that the low surface energy of the iodine monolayer leads to negligible interaction between G4 molecules and iodine adlayer, resulting in less perturbations of the structure by the solid phase and also an increase of push‐through force. Charts of friction forces vs. normal load are found to be independent of applied potential and the concentration of water.

Tribological behaviour of SiC and AL2O3 filled glass-epoxy composite

Metal glass fibre reinforced composites which are considered as advanced composite materials play a significant role in aerospace, marine and automotive industries. In the current study, an attempt has been made to examine the tribological characteristics of glass fibre reinforced plastic (GFRP) composite filled with aluminium oxide (Al2O3) and silicon carbide (SiC) powder particles. Experiments were performed on pin-on-disc tribometer to evaluate the friction and wear rate as a function of normal load and sliding velocity under different conditions. For each composition of glass-epoxy composite filled with and without fillers, sliding tests were performed with normal load (20 N, 40 N, 60 N, 80 N 100 N) and sliding velocity (2.62 m/s, 4.18 m/s, 5.23 m/s, 6.85 m/s, 7.85 m/s) respectively. The metal GFRP composites were fabricated using hand-lay-up technique. The filler content (SiC &amp; Al2O3) in epoxy-glass composite were varied. SiC was varied from 0 to 10% while Al2O3 was kept constant at 5%. To study the worn surface of glass-epoxy composite material scanning electronic microscopy is used. Before and after the experiment, weights of the composites (pin specimens) were studied on digital balance for wear loss. The present studies reported that the fabricated metal epoxy-fibre composite has performed excellent wear resistance when compared with epoxy-fibre composite without metal powders. The present work findings offer new insights into reinforcement in epoxy-glass composites with metal powders.

Effect of minor La addition on wear behaviour of Mg-10Dy alloy

Magnesium alloys have attracted significant attention as a potential replacement material for aluminium alloys in the automobile industry due to their superior strength-to-weight ratio. The addition of rare earth elements to Mg alloys enhances its strength and tribological properties owing to the solid solution strengthening as well as increased melting temperatures of the second phase. The aim of the current study is to examine the effect of minor La addition on the wear behaviour of as-cast Mg-rare-earth alloy (Mg-10 wt%Dy) in dry sliding conditions at different loads. The addition of rare earth elements to the magnesium alloys improves the wear strength effectively at different loads. The experiments were performed using ball-on-disc tribometer with a steel ball counterface as a function of normal load and at a constant sliding velocity. The wear surfaces were analyzed using a 3D profilometer and a field emission scanning electron microscopy to investigate wear rate and wear mechanisms. It was observed that due to the formation of stable oxide surface layers and improved hardness of La containing alloy, the wear rate is significantly lower than the Mg-10Dy alloy at different applied normal loads. Abrasion, delamination, oxidation, and plastic deformation were established as the governing wear mechanisms.

Spark Plasma Sintering and tribological behavior of Ti3SiC2–Ti5Si3–TiC composites

Herein, we study the effect of TiC content on the tribological behavior of four Ti3SiC2/Ti5Si3/TiC composites, prepared through Spark Plasma Sintering. The tribological properties were investigated under dry sliding, against Al2O3 counterpart at room temperature, under different normal loads and sliding speeds. Vickers indentation results showed that the composites preserve some damage tolerance properties. Scanning Electron Microscopy (SEM) and Raman spectroscopy results showed that the low wear stage is associated with the formation of a lubricious tribofilm consisting of a mixture of Ti6O11 Magnéli-phase and graphitic carbon. On the other hand, the tribo-oxidation products of the free TiC composite were identified as a mixture of TiO2 and SiO2 oxides. The composite reinforced up to 25 wt % TiC showed no transition from the low to the high wear rate as a function of normal loads. The influence of processing variables on microstructure development and wear mechanisms of the composites is discussed.

Bioinspired Adhesion Polymers: Wear Resistance of Adsorption Layers.

Mussel adhesive polymers owe their ability to strongly bind to a large variety of surfaces under water to their high content of 3,4-dihydroxy-l-phenylalanine (DOPA) groups and high positive charge. In this work, we use a set of statistical copolymers that contain medium-length poly(ethylene oxide) side chains that are anchored to the surface in three different ways: by means of (i) electrostatic forces, (ii) catechol groups (as in DOPA), and (iii) the combination of electrostatic forces and catechol groups. A nanotribological scanning probe method was utilized to evaluate the wear resistance of the formed layers as a function of normal load. It was found that the combined measurement of surface topography and stiffness provided an accurate assessment of the wear resistance of such thin layers. In particular, surface stiffness maps allowed us to identify the initiation of wear before a clear topographical wear scar was developed. Our data demonstrate that the molecular and abrasive wear resistance on silica surfaces depends on the anchoring mode and follows the order catechol groups combined with electrostatic forces > catechol groups alone > electrostatic forces alone. The devised methodology should be generally applicable for evaluating wear resistance or "robustness" of thin adsorbed layers on a variety of surfaces.

Evaluation of Wear Properties of Stir Cast AA7050 -10% B&lt;sub&gt;4&lt;/sub&gt;C &lt;i&gt;Ex Situ&lt;/i&gt; Composite through Fuzzy-TOPSIS MCDM Method

The present paper discussed the dry sliding wear and friction behavior of flux assisted stir cast AA7050-10% B4C composite. The K2TiF6 flux improves the wettability of B4C in molten aluminium. The casted composite were heat treated as per T-6 standard. The microstructure studies confirm the uniform distribution of B4C with the layers of Ti compound around it. Both As Casted Composite hereafter called as ACC and Heat Treated Composite hereafter called as HTC under gone dry sliding wear test at room temperature. The experiments were designed using Taguchi L18 mixed design. The responses of the experiment were optimized using fuzzy-TOPSIS MCDM method. From the experimental investigation it was concluded that wear rate of the composite material is a function of normal loads and sliding speed. Moreover, wear rate, coefficient of friction and amount of heat generation for HTC is comparatively less than ACC. This may due to the homogeneous distribution of particles and also formation proper interfacial bond between matrix and reinforcements after heat treatment.

Tribological characterization of jaspilite by linear scratch test

Rotary drilling is usually done with diamond-impregnated drill bits. These tools may present an unsatisfactory lifespan when working on a banded iron formation of Carajás Mineral Province, Brazil, known as jaspilite, a complex material composed of alternated bands of silicates (jasper) and iron oxides, and quartz veins. The performance of this bit is linked to the interaction between the diamond and the jaspilite, which is little understood. The abrasive wear response of this tribosystem has been investigated by a series of single-point scratch tests using Rockwell C, Vickers and Knoop diamond indenters as function of normal load (0.2–90 N). The effect of the distance between parallel scratches, which range from 5 times the scratch width to total superimposition, scratching speed (0.01–1 mm/s) and environmental conditions (dry, distilled water and bentonite drilling fluid) on wear and friction behavior were studied with Vickers indenter. Severe wear by chipping was dominant in all loads with Vickers indenter, at lower speeds and lubricated conditions. Mild wear mechanisms (such as burnishing, ploughing and scale-like cracking) had been observed in tests with Rockwell and Knoop indenter, at high speeds and in iron oxides. A correlation between wear mechanisms and friction was observed, except in the tests varying speed and environmental conditions. Furthermore, the degree of superimposition had no influence on friction and wear mechanisms.

On the normal contact stiffness and contact resonance frequency of rough surface contact based on asperity micro-contact statistical models

Contact stiffness is an important parameter for describing the interface characteristics in many engineering applications. In this paper, five different statistical micro-models including the Greenwood-Williamson (GW), Zhao-Maietta-Chang (ZMC), Kogut-Etsion (KE), Jackson-Green (JG) and Brake are employed to predict the normal contact stiffness for rough surface contact. It is found that the expressions of contact stiffness obtained using the statistical micro-models are very complex and the direct relationship between the contact stiffness and normal load is not available. Accordingly, an explicit approximated expression for contact stiffness is established in terms of normal load based on the results of numerical simulations. The normal contact stiffness as a function of normal load can be approximated using a power law, in which the coefficient and power are related to surface roughness parameters, material properties as well as nominal contact area. The close agreement between the predicted results and full numerical simulations verify the accuracy of the established explicit expression. The contact stiffness calculated using the predictive expressions are also compared with available experimental results from both ultrasonic method and contact resonance method. Further, the explicit expression of contact resonance frequency for rough surface contact with respect to the normal load is also provided, which can be used to evaluate the contact resonance frequency. The predicted contact resonance frequency is also validated through comparing with experimental results.

Lateral hardness and the scratch resistance of glasses in the Na2O-CaO-SiO2 system

We report on the lateral hardness of glasses from the Na2O-CaO-SiO2 (NCS) system, including CS and NS binaries. Quantitative data are provided on the work of lateral deformation, obtained through instrumented indentation by monitoring the lateral force as a function of normal load. Experiments were conducted in the regime of elastic-plastic deformation, that is, in the absence of microscopic cracking for normal loads of 50–70 mN. The scratch hardness is determined from the work of deformation per deformed volume. Parallel observations of the elastic properties are undertaken so as to reference scratching data to glass composition and structure. We find that structural densification and high rigidity favor higher scratch hardness. For the considered range of chemical compositions, the scratch hardness exhibits an approximately linear correlation with bulk modulus and packing density. It increases in the direction of compositions with higher content of CaO, and decreases with the content of Na2O. Furthermore, we find a strongly linear correlation between scratch hardness and the deviation of experimental compressibility from the mean-field estimate of the Makishima-Mackenzie model. This points to the importance of intermediate-range structural heterogeneity in the scratching process.

Experiment and simulation of friction coefficient of polyoxymethylene

PurposeThe purposes of this paper include studying the friction coefficient of polyoxymethylene (POM) under a broad range of normal load and sliding velocity; developing a mathematical model of friction coefficient of POM under a broad range of normal loads and sliding velocities; and applying the model to dynamic finite element (FE) analysis of mechanical devices containing POM components.Design/methodology/approachThrough pin-on-disc experiment, the friction coefficient of POM in different normal loads and sliding velocities is investigated; the average contact pressure is between 5 and 15 Mpa and the sliding velocity is from 0.05 to 0.9 m/s. A friction algorithm is developed and embedded in the FE model to simulate the friction of POM in different normal loads and sliding velocities.FindingsThe friction coefficient of POM against steel declines with the increase of normal loads when the contact pressure is between 5 and 15 Mpa. The friction coefficient of POM against steel increases markedly when the sliding velocity is between 0.05 and 0.15 m/s, it decreases sharply between 0.15-0.45 m/s and then it stabilizes at high sliding velocity between 0.45 and 0.9 m/s. The friction coefficient of POM in different working operations has a significant effect on contact stress and shear stress. The simulation data and experiment data of POM friction force fit very well; therefore, it can be concluded that the friction algorithm and FE model are accurate.Originality/valueThe friction coefficient of POM under a broad range of normal loads and sliding velocities is investigated. The friction coefficient model of POM is established as a function of normal loads and sliding velocities in the dry sliding condition. A friction algorithm is developed and embedded in the FE model of the friction of POM. The mathematical model of the friction coefficient accurately agrees with the experiment data, and simulation data and experiment data of the POM friction force fit very well.

Shear thinning in non-Brownian suspensions.

We study the flow of suspensions of non-Brownian particles dispersed into a Newtonian solvent. Combining capillary rheometry and conventional rheometry, we evidence a succession of two shear thinning regimes separated by a shear thickening one. Through X-ray radiography measurements, we show that during each of those regimes, the flow remains homogeneous and does not involve particle migration. Using a quartz-tuning fork based atomic force microscope, we measure the repulsive force profile and the microscopic friction coefficient μ between two particles immersed into the solvent, as a function of normal load. Coupling measurements from those three techniques, we propose that (1) the first shear-thinning regime at low shear rates occurs for a lubricated rheology and can be interpreted as a decrease of the effective volume fraction under increasing particle pressures, due to short-ranged repulsive forces and (2) the second shear thinning regime after the shear-thickening transition occurs for a frictional rheology and can be interpreted as stemming from a decrease of the microscopic friction coefficient at large normal load.

Ionic Liquid Lubrication of Stainless Steel: Friction is Inversely Correlated with Interfacial Liquid Nanostructure

Atomic force microscopy (AFM) is used to measure the friction of a stainless steel surface lubricated with six different ionic liquids (ILs). The measurements reveal that, contrary to expectations, friction and the degree of interfacial ionic liquid nanostructure are inversely correlated. Six ILs were confined between a sharp Si tip and a stainless steel surface, and the friction force was measured as a function of normal load. Trihexyl(tetradecyl)phosphonium bis(trifluoromethane)sulfonamide (P6,6,6,14 TFSI) and trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate (P6,6,6,14 (iC8)2PO2) are the most effective lubricants, reducing lateral forces and friction coefficients by up to 3 times compared with the imidazolium-based ILs and the shorter-chained P4,4,4,1 TFSI. Force–separation profiles reveal no obvious interfacial layers for P6,6,6,14 (iC8)2PO2 and P6,6,6,14 TFSI, in contrast to extensive layering for the other ILs. The bulkiness of the [P6,6,6,14]+ cation weakens the electrostatic in...

Wear maps of HIP sintered Si3N4/MLG nanocomposites for unlike paired tribosystems under ball-on-disc dry sliding conditions

Hot isostatically pressed monolithic and multilayer graphene (MLG) reinforced silicon nitride nanocomposites have been investigated by ball-on-disc tests under variable loading conditions. Tests were carried out at room temperature with three different normal loads (10, 40 and 80N), and six sliding speeds (10, 20, 50, 100, 150 and 200mm/s) without lubrication using commercial silicon carbide ball counterparts for 54 tribosystems. The aim of the research work was to construct 2D wear transition and 3D wear rate maps of the investigated ceramic composites. The 3D maps visualizing the specific wear rate and the dimensionless wear coefficient as a function of normal load and sliding speed have been completed with morphological analysis of wear tracks and identification of the dominant wear mechanisms. The presented ceramic wear maps provide useful aid for predicting the wear performance of the investigated nanocomposites under various loading conditions.

Characterization of air plasma-sprayed yttria-stabilized zirconia coatings deposited with nitrogen

Air plasma-sprayed (APS) yttria-stabilized zirconia (YSZ) conventional and nanostructured coatings were deposited with nitrogen as the primary plasma gas. Nanostructured coatings were deposited as a function of critical plasma spray parameter (CPSP). Microstructural characteristics, e.g., phase distribution, porosity, microhardness, percentage of partially melted (PM) regions, surface roughness, and wear performance, were evaluated for deposited coatings. Effect of CPSP on wear performance of coatings was most prominent at highest normal load considered. Conventional and nanostructured coatings deposited with nitrogen showed different trends for specific wear rate as a function of normal load. While specific wear rate for conventional coatings was nearly constant, it increased with increasing load for nanostructured coatings. Thus, even though nanostructured coatings provided better wear resistance at lower normal loads, conventional YSZ coatings become more wear resistant at higher loads. For example, at highest normal load considered, specific wear rate of conventional coatings was around 12 % smaller than that for corresponding nanostructured coatings.

Scaling the sandbox—Mechanical (dis) similarities of granular materials and brittle rock

AbstractAnalog sandbox experiments are an important tool to understand brittle tectonic deformation. To date, most experiments are interpreted kinematically only. With the advent of reliable, small‐scale force sensors, however, their dynamic evolution becomes available for analysis, offering new insights into the transient evolution of tectonic systems. Both rock and granular materials show an evolution of strain hardening and weakening during loading in the brittle‐plastic regime, but so far, this similarity has only been appreciated qualitatively. As strain weakening is a vital parameter controlling fault reactivation and lifetime, it requires proper scaling. We therefore measured and analyzed two common granular analog model materials (quartz sand and glass microbeads) using ring‐shear tests at a range of normal loads typical for analog experiments. We find two different modes of strain weakening as a function of normal load: Strain weakening at normal loads &lt;1 kPa is due to partial loss of extrapolated cohesion, while at normal loads &gt;1 kPa it is controlled by reduction of internal friction, which is consistent with previous measurements in this range. We show that this introduces a scale dependence into the scaling and restricts the possible use of the tested materials to crustal‐scale models with a length scaling factor of . For these we quantitatively compare the model materials' transient strength evolution to that known from natural rock and the Earth's crust.

Experimental Investigation of aluminum doping crumb rubber/epoxy composite in reciprocating motion

The experimental investigation of reciprocating motion between the aluminum doped crumb rubber /epoxy composite and the steel ball has been carried out under Reciprocating Friction Tester, TR-282 to study the wear and coefficient of frictions using different normal loads (0.4Kg, 0.7Kgand1Kg), differentfrequencies (10Hz, 25Hz and 40Hz).The wear is a function of normal load, reciprocating frequency, reciprocating duration and the composition of the material. The percentage of aluminum presents in the composite changesbut the other components remain the same.The four types of composites are fabricated by compression molding process having 0%, 10%, 20% and 30% Al. The effect of different parameters such as normal load, reciprocating frequency and percentage of aluminum has been studied. It is observed that the wear and coefficient of friction is influenced by the parameters. The tendency of wear goes on decreasing with the increase of normal load and it is minimum for a composite having 10%aluminum at a normal load of 0.7Kg and then goes on increasing at higher loads for all types of composite due to the adhesive nature of the composite. The coefficient of friction goes on decreasing with increasing normal loads due to the formation of thin film as an effect of heat generation with normal load.

In Vivo Measurement of the Friction Between Human Skin and Different Medical Compression Stockings

The friction behaviour of five medical compression stockings (MCSs) against forearm skin was investigated in vivo as a function of normal load under dry and wet conditions. In addition, the interfacial moisture transport and skin hydration were analysed to understand the influence on friction. The friction coefficients of dry fabrics showed no significant differences between a traditional MCS and versions with modified material composition and base structure. Under wet conditions, the modified MCS fabrics showed considerably lower friction coefficients than the traditional MCS fabric. Changes in the material composition led to 20–30 % lower friction coefficients, different base structures to 50–60 % lower friction. The water transport properties of the MCS fabrics suggest that removal of interfacial water is useful for reducing the friction between MCSs and skin. The results provide information for the optimisation of MCSs regarding improved comfort and moisture transport properties.

Structure and nanotribology of thermally deposited gold nanoparticles on graphite

We present experiments involving the structural and frictional characterization of gold nanoparticles (AuNP) thermally deposited on highly oriented pyrolytic graphite (HOPG). The effect of thermal deposition amount, as well as post-deposition annealing on the morphology and distribution of gold on HOPG is studied via scanning electron microscopy (SEM) measurements, while transmission electron microscopy (TEM) is utilized to confirm the crystalline character of the nanoparticles. Lateral force measurements conducted via atomic force microscopy (AFM) under ambient conditions are employed to investigate the nanotribological properties of the gold nanoparticles as a function of normal load. Finally, the increase in lateral force experienced at the edges of the nanoparticles is studied as a function of normal load, as well as nanoparticle height. As a whole, our results constitute a comprehensive structural and frictional characterization of the AuNP/HOPG material system, forming the basis for nanotribology experiments involving the lateral manipulation of thermally deposited AuNPs on HOPG via AFM under ambient conditions.