scholarly journals Femtosecond Laser Micro-/Nano-Texturing of Stainless Steels for Surface Property Control

Micromachines ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 512 ◽  
Author(s):  
Aizawa ◽  
Inohara ◽  
Wasa
Keyword(s):  
Contact Angle ◽  
Fractal Dimension ◽  
Femtosecond Laser ◽  
Surface Properties ◽  
Stainless Steels ◽  
Surface Property ◽  
Textured Surface ◽  
Surface Geometry ◽  
Static Contact ◽  
Property Control

Surface geometry has had an influence on the surface property, in addition to the intrinsic surface energy, of materials. Many physical surface modification methods had been proposed to control the solid surface geometry for modification of surface properties. Recently, short-pulse lasers were utilized to perform nano-texturing onto metallic and polymer substrates for the improvement of surface properties. Most of the papers reported that the hydrophilic metallic surface was modified to have a higher contact angle than 120–150°. Little studies explained the relationship between surface geometry and surface properties. In the present study, the laser micro-/nano-texturing was developed to describe this surface-geometric effect on the static contact angles for pure water. Micropatterns with multi spatial frequencies are designed and synthesized into a microtexture. This tailored microtexture was utilized to prepare for computer aided machining (CAM) data to control the femtosecond laser beams. The nano-length ripples by laser induced periodic surface structuring (LIPSS) supposed onto this microtexture to form the micro-/nano-texture on the AISI304 substrate surface. Computational geometry was employed to describe this geometric profile. The fractal dimension became nearly constant by 2.26 and insensitive to increase of static contact angle (θ) for θ > 150°. Under this defined self-similarity, the micro-/nano-textured surface state was controlled to be super-hydrophobic by increasing the ratio of the highest spatial frequency in microtextures to the lowest one. This controllability of surface property on the stainless steels was supported by tailoring the wavelength and pitch of microtextures. Exposure testing was also used to evaluate the engineering durability of this micro-/nano-textured surface. Little change of the measured fractal dimension during the testing proved that this physically modified AISI304 surface had sufficient stability for its long-term usage in air.

Smooth and Transparent Films Showing Paradoxical Surface Properties: The Lower the Static Contact Angle, the Better the Water Sliding Performance

Langmuir ◽  
2019 ◽  
Vol 35 (21) ◽  
pp. 6822-6829
Author(s):  
Sohei Kaneko ◽  
Chihiro Urata ◽  
Tomoya Sato ◽  
Roland Hönes ◽  
Atsushi Hozumi
Keyword(s):  
Contact Angle ◽  
Surface Properties ◽  
Static Contact Angle ◽  
Transparent Films ◽  
Static Contact

Dropwise Condensation Underneath Chemically Textured Surfaces: Simulation and Experiments

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Basant Singh Sikarwar ◽  
Nirmal Kumar Battoo ◽  
Sameer Khandekar ◽  
K. Muralidhar
Keyword(s):  
Contact Angle ◽  
Model Simulation ◽  
Contact Angle Hysteresis ◽  
Saturation Temperature ◽  
Static Contact Angle ◽  
Order Effects ◽  
Textured Surface ◽  
Dropwise Condensation ◽  
Textured Surfaces ◽  
Static Contact

Experimental observations of dropwise condensation of water vapor on a chemically textured surface of glass and its detailed computer simulation are presented. Experiments are focused on the pendant mode of dropwise condensation on the underside of horizontal and inclined glass substrates. Chemical texturing of glass is achieved by silanation using octyl-decyl-tri-chloro-silane (C18H37C13Si) in a chemical vapor deposition process. The mathematical model is built in such a way that it captures all the major physical processes taking place during condensation. These include growth due to direct condensation, droplet coalescence, sliding, fall-off, and renucleation of droplets. The effects arising from lyophobicity, namely, the contact angle variation and its hysteresis, inclination of the substrate, and saturation temperature at which the condensation is carried out, have been incorporated. The importance of higher order effects neglected in the simulation is discussed. The results of model simulation are compared with the experimental data. After validation, a parametric study is carried out for cases not covered by the experimental regime, i.e., various fluids, substrate inclination angle, saturation temperature, and contact angle hysteresis. Major conclusions arrived at in the study are the following: The area of droplet coverage decreases with an increase in both static contact angle of the droplet and substrate inclination. As the substrate inclination increases, the time instant of commencement of sliding of the droplet is advanced. The critical angle of inclination required for the inception of droplet sliding varies inversely with the droplet volume. For a given static contact angle, the fall-off time of the droplet from the substrate is a linear function of the saturation temperature. For a given fluid, the drop size distribution is well represented by a power law. Average heat transfer coefficient is satisfactorily predicted by the developed model.

Tuning the Surface Properties of Elastomers Using Hydrocarbon-Based Mechanically Assembled Monolayers

2001 ◽  
Vol 710 ◽  
Author(s):  
Kirill Efimenko ◽  
Jan Genzer
Keyword(s):  
Contact Angle ◽  
Fine Structure ◽  
Surface Structure ◽  
Surface Properties ◽  
Molecular Orientation ◽  
Angle Measurements ◽  
Static Contact ◽  
Contact Angle Measurements ◽  
Assembled Monolayers ◽  
Excellent Stability

ABSTRACTWe use static contact angle measurements and near-edge absorption fine structure to elucidate the surface structure and molecular orientation of hydrocarbon-based mechanically assembled monolayers (H-MAMs), structures formed by combination of assembly of alkyl moieties onto flexible elastomeric substrates and mechanical manipulation of the substrates. Specifically, we report that the organization of the grafted molecular array (“liquid”-like vs. solid-like) can be tailored by varying the degree of stretching of the elastomeric substrate. We also show that the H-MAM surfaces exhibit excellent stability.

The effect of CH4/H2 ratio on the surface properties of HDPE treated by CHx ion beam bombardment

2016 ◽  
Vol 30 (17) ◽  
pp. 1650214 ◽  
Author(s):  
Wanyu Ding ◽  
Yuanyuan Guo ◽  
Dongying Ju ◽  
Susumu Sato ◽  
Teruo Tsunoda
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Surface Properties ◽  
Chemical Bond ◽  
High Density Polyethylene ◽  
Ion Beam ◽  
High Density ◽  
Static Contact Angle ◽  
Structures And Properties ◽  
Static Contact

The surface of high density polyethylene (HDPE) substrate was bombarded by the CH[Formula: see text] group ion beam, which was generated by the mixture of CH4/H2. Varying the CH4/H2 ratio, HDPE surfaces with different chemical bond structures and properties were obtained. Raman and XPS results show that [Formula: see text] and [Formula: see text] bond structures are formed at HDPE surface bombarded by CH[Formula: see text] group ions. The [Formula: see text] bond fraction at bombarded HDPE surface depends on the H2 ratio in CH4/H2 mixture, because the H ion/atom/molecule can improve the growth of [Formula: see text] bond structure. For HDPE surface bombarded by CH4/H2 = 50/50, [Formula: see text] bond fraction reaches the maximum of 30.5%, the surface roughness decreases to 17.04 nm, and the static contact angle of polar H2O molecule increased to 140.2[Formula: see text].

Thermodynamic analysis and injection molding of hierarchical superhydrophobic polypropylene surfaces

2019 ◽  
Vol 40 (1) ◽  
pp. 86-97
Author(s):  
Can Weng ◽  
Jin Yang ◽  
Fei Wang ◽  
Tao Ding ◽  
Zhanyu Zhai
Keyword(s):  
Contact Angle ◽  
Injection Molding ◽  
Thermodynamic Analysis ◽  
Hierarchical Structure ◽  
Hierarchical Structures ◽  
Equilibrium Contact Angle ◽  
Surface Model ◽  
Textured Surface ◽  
Static Contact ◽  
The Hierarchical Structure

Abstract In this study, thermodynamic analysis of the hierarchical structure of the 3D cylinder-textured surface model was performed. The wetting states at different penetration depths, the effects of three components on the wetting properties, and all equilibrium contact angle of the hierarchical structure were investigated. It was found that the interaction between micropillars and nanopillars can affect the transition energy barrier and the transition pitch in the wetting-state transition process. This showed that all components would play a key role in enhancing the surface hydrophobicity. Polypropylene (PP) surfaces with mono micropillars and hierarchical structures were both fabricated by injection molding. Mold inserts for hierarchical structures were obtained by the combination of a punching plate and an anodized aluminum alloy plate. The static contact angle (CA) and the roll-off angle of injection-molded PP surfaces were measured and analyzed from the perspective of thermodynamic analysis. With the hierarchical structures, a static CA of about 163° as well as a roll-off angle of about 5° was approached. Compared with a mono micropillar-structured PP surface, the hierarchical-structured PP surface has a larger static CA and a smaller roll-off angle. The work demonstrates an inexpensive and reproducible technique to fabricate function-designed controlled hierarchical structures on PP material.

scholarly journals Surface Characterization and Copper Release of a-C:H:Cu Coatings for Medical Applications

Coatings ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 119 ◽  
Author(s):  
Stefan Nißen ◽  
Jan Heeg ◽  
Marion Wienecke ◽  
Detlef Behrend ◽  
Mareike Warkentin ◽  
...  
Keyword(s):  
Contact Angle ◽  
Surface Properties ◽  
Surface Characterization ◽  
Bacterial Colonization ◽  
Composite Coatings ◽  
Anodic Stripping Voltammetry ◽  
Ringer’S Solution ◽  
Copper Release ◽  
Static Contact ◽  
Cu Ions

This paper focuses on the surface properties of a-C:H:Cu composite coatings for medical devices and how the release of Cu2+ ions from such coatings can be controlled. The released Cu ions have the potential to act as a bactericidal agent and inhibit bacterial colonization. A PVD–PECVD hybrid process was used to deposit a-C:H:Cu composite coatings onto Ti6Al4V substrates. We examine the layer surface properties using atomic force microscopy and static contact angle measurements. An increasing surface roughness and increasing contact angle of Ringer’s solution was measured with increasing copper mole fraction (XCu) in the coatings. The contact angle decreased when a supplementary bias voltage of −50 V was used during the a-C:H:Cu deposition. These findings are in line with earlier published results regarding these types of coatings. The release of Cu2+ ions from a-C:H:Cu coatings in Ringer’s solution was measured by anodic stripping voltammetry. Different layer structures were examined to control the time-resolved Cu release. It was found that the Cu release depends on the overall XCu in the a-C:H:Cu coatings and that an additional a-C:H barrier layer on top of the a-C:H:Cu layer effectively delays the release of Cu ions.

Controlling porosity and density of nanocellulose aerogels for superhydrophobic light materials

TAPPI Journal ◽  
2018 ◽  
Vol 17 (03) ◽  
pp. 145-153 ◽  
Author(s):  
Chengua Yu ◽  
Feng Wang ◽  
Shiyu Fu ◽  
Lucian Lucia
Keyword(s):  
Contact Angle ◽  
Freeze Drying ◽  
Engine Oil ◽  
High Porosity ◽  
Water Mixture ◽  
Waste Engine Oil ◽  
Hydrophobically Modified ◽  
Static Contact ◽  
Oil Water ◽  
Hydrophobic Material

A very low-density oil-absorbing hydrophobic material was fabricated from cellulose nanofiber aerogels–coated silane substances. Nanocellulose aerogels (NCA) superabsorbents were prepared by freeze drying cellulose nanofibril dispersions at 0.2%, 0.5%, 0.8%, 1.0%, and 1.5% w/w. The NCA were hydrophobically modified with methyltrimethoxysilane. The surface morphology and wettability were characterized by scanning electron microscopy and static contact angle. The aerogels displayed an ultralow density (2.0–16.7 mg·cm-3), high porosity (99.9%–98.9%), and superhydrophobicity as evidenced by the contact angle of ~150° that enabled the aerogels to effectively absorb oil from an oil/water mixture. The absorption capacities of hydrophobic nanocellulose aerogels for waste engine oil and olive oil could be up to 140 g·g-1 and 179.1 g·g-1, respectively.

Perceived Glossiness: Beyond Surface Properties

2019 ◽  
Vol 2019 (1) ◽  
pp. 37-42
Author(s):  
Davit Gigilashvili ◽  
Jean-Baptiste Thomas ◽  
Marius Pedersen ◽  
Jon Yngve Hardeberg
Keyword(s):  
Surface Properties ◽  
Human Subjects ◽  
Surface Geometry ◽  
Surface Reflection ◽  
Different Color

Gloss is widely accepted as a surface- and illuminationbased property, both by definition and by means of metrology. However, mechanisms of gloss perception are yet to be fully understood. Potential cues generating gloss perception can be a product of phenomena other than surface reflection and can vary from person to person. While human observers are less likely to be capable of inverting optics, they might also fail predicting the origin of the cues. Therefore, we hypothesize that color and translucency could also impact perceived glossiness. In order to validate our hypothesis, we conducted series of psychophysical experiments asking observers to rank objects by their glossiness. The objects had the identical surface geometry and shape but different color and translucency. The experiments have demonstrated that people do not perceive objects with identical surface equally glossy. Human subjects are usually able to rank objects of identical surface by their glossiness. However, the strategy used for ranking varies across the groups of people.

scholarly journals Research and Prediction of Wettability of Irregular Square Column Structure on Polymethyl Methacrylate (PMMA) Surface Prepared by Femtosecond Laser

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 529
Author(s):  
Bangfu Wang ◽  
Juan Song
Keyword(s):  
Contact Angle ◽  
Femtosecond Laser ◽  
Prediction Model ◽  
Polymethyl Methacrylate ◽  
Groove Width ◽  
Complete Wetting ◽  
Column Structure ◽  
Pmma Surface ◽  
Incomplete Wetting ◽  
Wetting Model

Based on the contact angle prediction model of a traditional square column structure, the prediction models for wettability of a parallelogram square column structure (PSCS) on polymethyl methacrylate (PMMA) surface prepared by femtosecond laser were established. An experiment was conducted to analyze the rationality of the established complete wetting model and incomplete wetting model. It was found that the incomplete wetting prediction model of the square column structure was more in line with the actual situation. For PSCS, the length of both the long and short sides of the boss and the width of the groove exerted an impact on the contact angle prediction results. Under the condition that the length of the long and short sides of the boss remained unchanged and the groove width increased, the contact angle increased under complete wetting and incomplete wetting. In contrast, under the condition that the long side length of the boss and the groove width remained unchanged and the short side length of the boss increased, the contact angle increased under complete wetting but decreased under incomplete wetting. The maximum contact angle reached 135.65°, indicating that PSCS on PMMA surface enhanced the surface hydrophobicity of the material.

scholarly journals Biomimetic Approach for the Elaboration of Highly Hydrophobic Surfaces: Study of the Links between Morphology and Wettability

Biomimetics ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 38
Author(s):  
Quentin Legrand ◽  
Stephane Benayoun ◽  
Stephane Valette
Keyword(s):  
Contact Angle ◽  
Ginkgo Biloba ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Textured Surfaces ◽  
Replication Process ◽  
Wetting Behavior ◽  
Static Contact ◽  
Biomimetic Approach ◽  
Highly Hydrophobic

This investigation of morphology-wetting links was performed using a biomimetic approach. Three natural leaves’ surfaces were studied: two bamboo varieties and Ginkgo Biloba. Multiscale surface topographies were analyzed by SEM observations, FFT, and Gaussian filtering. A PDMS replicating protocol of natural surfaces was proposed in order to study the purely morphological contribution to wetting. High static contact angles, close to 135∘, were measured on PDMS replicated surfaces. Compared to flat PDMS, the increase in static contact angle due to purely morphological contribution was around 20∘. Such an increase in contact angle was obtained despite loss of the nanometric scale during the replication process. Moreover, a significant decrease of the hysteresis contact angle was measured on PDMS replicas. The value of the contact angle hysteresis moved from 40∘ for flat PDMS to less than 10∘ for textured replicated surfaces. The wetting behavior of multiscale textured surfaces was then studied in the frame of the Wenzel and Cassie–Baxter models. Whereas the classical laws made it possible to describe the wetting behavior of the ginkgo biloba replications, a hierarchical model was developed to depict the wetting behavior of both bamboo species.

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