Unexpected Frictional Behavior of Laser-Textured Hydrophobic Surfaces

Jendoubi, Hiba; Smerdova, Olga; Brunetière, Noël

doi:10.3390/lubricants9030031

Cited by 8 publications

(3 citation statements)

References 30 publications

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“…The effect of faster sliding by the 150 µm laser-grooved block was slightly more discernable on ice closer to the melting temperature at −2.2 °C. At −8.8 °C, the 150 µm laser-grooved slider was only slightly faster than the grooved and polished reference slider, possibly due to larger resistance-to-sliding from roughness on colder ice [32]. It is interesting that larger differences in the sliding speed were observed on warmer ice, despite overall slower sliding.…”

Section: Sliding Speed Of Laser-grooved Blocksmentioning

confidence: 93%

Surface Hierarchy: Macroscopic and Microscopic Design Elements for Improved Sliding on Ice

et al. 2021

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Frictional interaction with a surface will depend on the features and topography within the contact zone. Describing this interaction is particularly complex when considering ice friction, which needs to look at both the macroscopic and microscopic levels. Since Leonardo da Vinci shared his findings that roughness increases friction, emphasis has been placed on measuring surface coarseness, neglecting the contact area. Here, a profilometer was used to measure the contact area at different slicing depths and identify contact points. Metal blocks were polished to a curved surface to reduce the contact area; further reduced by milling 400 µm grooves or laser-micromachining grooves with widths of 50 µm, 100 µm, and 150 µm. Sliding speed was measured on an inclined ice track. Asperities from pileup reduced sliding speed, but a smaller contact area from grooves and a curved sliding surface increased sliding speed. An analysis of sliding speed versus contact area from incremental slicing depths showed that a larger asperity contact surface pointed to faster sliding, but an increase in the polished surface area reduced sliding. As such, analysis of the surface at different length scales has revealed different design elements—asperities, grooves, curved zones—to alter the sliding speed on ice.

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Section: Sliding Speed Of Laser-grooved Blocksmentioning

confidence: 93%

Surface Hierarchy: Macroscopic and Microscopic Design Elements for Improved Sliding on Ice

et al. 2021

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“…8 Dai et al 9 used laser processing technology to prepare circular, triangular and water-drop-shaped micro-textures on the surface of bearing steel, showed that the surface micro-texture will produce micro-fluid hydrodynamic effect, and the effect of water droplet texture and triangular texture was better. Hiba et al 10 used femtosecond laser to process lattice hexagonal micro-textures on polytetrafluoroethylene polymer samples, showed that micro-textured surfaces have higher friction coefficients than smooth surfaces. Tang et al 11 showed that the change of dimple area fraction is of great significance to reduce friction and wear, the optimum dimple area fraction of 5% can reduce friction and wear.…”

Section: Introductionmentioning

confidence: 99%

Performance analysis of tilting pad thrust bearing incorporating the surface roughness, texture and turbulence effect

Wang,

Zou,

Duan

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part J:

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In order to improve the lubrication performance of the friction pair, the effect of composite micro-texture on the lubrication performance of the tilting pad thrust bearing is studied. Based on the structural model of tilting pad thrust bearing considering composite micro-texture, the lubrication characteristics of thrust bearing with composite micro-texture parameters and tilting pad parameters are analyzed. At the same time, the theoretical model of tilting pad composite micro-texture bearing considering roughness and turbulence effect is established, and the performance of thrust bearing considering roughness and turbulence effect is studied. The results show that the performance of composite micro-textured bearings is better than that of single micro-textured bearings, the performance of tilting pad bearings is better than that of parallel pad bearings, and the performance of circular composite fish-shaped micro-textured tilting pad bearings is the best. The optimal bearing fulcrum position is near the inner diameter, and the optimal fulcrum circumferential inclination angle is about 27.5°. Considering the roughness and turbulence effect, the maximum pressure and bearing capacity of the bearing improves, and the friction coefficient significantly reduces.

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“…In water-lubricated hydrodynamic journal bearings, the polytetrafluoroethylene (PTFE) surface coatings are widely used because the friction property is improved and bearing life is extended. The physical properties of PTFE differ from metals in that their lower surface energy reduces friction, which makes the flow more difficult for fluids to adhere, and thus slip velocity exists in surface coatings [2][3][4]. Since the effect of slip velocity on fluid flow is significant, the effect of slip velocity on the static characteristics of bearings is considered, which will meet the actual conditions more.…”

Section: Introductionmentioning

confidence: 99%

A Three-Dimensional Slip Velocity Model for Water-Lubricated Hydrodynamic Journal Bearings

Cheng²,

Sun³

et al. 2022

JMSE

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Hydrodynamic journal bearings, coated with polytetrafluoroethylene (PTFE) and lubricated by water, have been widely used in ships and large-scale pumps, and the function is to maintain the stability of rotor system. However, slip velocity exists on the PTFE-coated surface, whose effect is still an open question. This study aims to investigate the static characteristics of water-lubricated hydrodynamic journal bearings under three-dimensional slip velocity boundary conditions. Firstly, under the non-slip boundary condition, the CFD (computational fluid dynamics) method with ANSYS Fluent is verified based on the Reynolds lubrication equation and the open literature. Then, a three-dimensional slip velocity equation that is based on the Navier slip velocity boundary condition is proposed and embedded into Fluent. Finally, the effects of slip length on the static characteristics are analyzed. Under the same eccentricity ratio, with the increase in slip length, the load capacity decreases due to the decrease of the pressure circumferential gradient, and the friction power decreases. Under the same eccentricity ratio and the same slip length, with the increase in the attitude angle, the load capacity and friction power increase. However, under the non-slip boundary condition, the effects of attitude angle on the load capacity and friction power are insignificant. This paper could provide a reference for studying slip velocity in the hydrodynamic journal bearing.

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Unexpected Frictional Behavior of Laser-Textured Hydrophobic Surfaces

Cited by 8 publications

References 30 publications

Surface Hierarchy: Macroscopic and Microscopic Design Elements for Improved Sliding on Ice

Surface Hierarchy: Macroscopic and Microscopic Design Elements for Improved Sliding on Ice

Performance analysis of tilting pad thrust bearing incorporating the surface roughness, texture and turbulence effect

A Three-Dimensional Slip Velocity Model for Water-Lubricated Hydrodynamic Journal Bearings

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