Fractal parameters developed to evaluate the effects of laser textured surface on oil contact angle and tribological parameters

2021 ◽  
Vol 33 (2) ◽  
pp. 022021
Author(s):  
Chang-Shuo Chang ◽  
Muhammad Arif Mahmood ◽  
Tsung-Wen Tsai ◽  
Chang-Fu Han ◽  
Chen-Kuei Chung ◽  
...  
Keyword(s):  
Contact Angle ◽  
Textured Surface ◽  
Fractal Parameters ◽  
Tribological Parameters

Addition of Cellulose Nanofibers to Control Surface Roughness for Hydrophobic Ceramic Coatings

2021 ◽  
Vol 21 (8) ◽  
pp. 4492-4497
Author(s):  
Eun Ae Shin ◽  
Gye Hyeon Kim ◽  
Jeyoung Jung ◽  
Sang Bong Lee ◽  
Chang Kee Lee
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Surface Energy ◽  
Water Contact Angle ◽  
Ceramic Coating ◽  
Cellulose Nanofibers ◽  
Ceramic Coatings ◽  
Coating Material ◽  
Textured Surface ◽  
Water Contact

Hydrophobic ceramic coatings are used for a variety of applications. Generally, hydrophobic coating surfaces are obtained by reducing the surface energy of the coating material or by forming a highly textured surface. Reducing the surface energy of the coating material requires additional costs and processing and changes the surface properties of the ceramic coating. In this study, we introduce a simple method to improve the hydrophobicity of ceramic coatings by implementing a textured surface without chemical modification of the surface. The ceramic coating solution was first prepared by adding cellulose nanofibers (CNFs) and then applied to a polypropylene (PP) substrate. The surface roughness increased as the amount of added CNFs increased, increasing the water contact angle of the surface. When the amount of CNFs added was corresponding to 10% of the solid content, the surface roughness average of the area was 43.8 μm. This is an increase of approximately 140% from 3.1 μm (the value of the surface roughness of the surface without added CNFs). In addition, the water contact angle of the coating with added CNF increased to 145.0°, which was 46% higher than that without the CNFs. The hydrophobicity of ceramic coatings with added CNFs was better because of changes in the surface topography. After coating and drying, the CNFs randomly accumulated inside the ceramic coating layer, forming a textured surface. Thus, hydrophobicity was improved by implementing a rugged ceramic surface without revealing the surface of the CNFs inside the ceramic layer.

scholarly journals Wettability on Different Surfaces

2020 ◽  
Author(s):  
Yeeli Kelvii Kwok
Keyword(s):  
Contact Angle ◽  
Textured Surface ◽  
Original Material ◽  
Textured Surfaces ◽  
Hydrophobic Surfaces ◽  
Hydrophilic Surfaces ◽  
Young's Equation

Wettability has been explored for 100 years since it is described by Young’s equation in 1805. It is all known that hydrophilicity means contact angle (θ), θ < 90°; hydrophobicity means contact angle (θ), θ > 90°. The utilization of both hydrophilic surfaces and hydrophobic surfaces has also been achieved in both academic and practical perspectives. In order to understand the wettability of a droplet distributed on the textured surfaces, the relevant models are reviewed along with understanding the formation of contact angle and how it is affected by the roughness of the textured surface aiming to obtain the required surface without considering whether the original material is hydrophilic or hydrophobic.

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.

scholarly journals Laser Texturing for Superwetting Titanium Alloy and Investigation of Its Erosion Resistance

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1547
Author(s):  
Zhiguo Wang ◽  
Jinpeng Song ◽  
Tianyi Wang ◽  
Huixin Wang ◽  
Qinghua Wang
Keyword(s):  
Contact Angle ◽  
Superhydrophobic Surface ◽  
Erosion Resistance ◽  
Surface Texturing ◽  
Laser Surface ◽  
Laser Surface Texturing ◽  
Textured Surface ◽  
Ti Alloy ◽  
Textured Surfaces ◽  
Superhydrophilic Surface

Erosion of materials is one of the major causes that lead to the malfunction of equipment and facilities, and surface texturing can be a solution for enhancement of erosion resistance. In this work, superwetting (superhydrophilic/superhydrophobic) titanium (Ti) alloy surface with periodic microstructure was prepared by a facile laser-based surface texturing approach which combines laser surface texturing and low-temperature annealing. The effect of laser-induced surface texture and wettability on the erosion resistance of the laser textured surface was studied. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to analyze the chemical surface microstructure and surface on the untreated and laser textured surfaces. The hardness and contact angle of the untreated surface, superhydrophilic surface and superhydrophobic surface were measured by microhardness tester and contact angle goniometer. Using an in-house built erosion experimental setup, the erosion resistance of the untreated surface, superhydrophilic surface and superhydrophobic surface was investigated. The experimental results demonstrate that micro-bumps are formed after laser surface texturing. In the meantime, the surface hardness for the laser textured surface with a step size of 150 μm is increased by 48% under the load of 1.961 N. Compared with the untreated surface, the erosion resistance is increased by 33.9%, 23.8% and 16.1%, respectively, for the superhydrophobic surface. The SEM results show that the untreated surface has large and deep impact pits, while the superhydrophobic surface only has small and shallow impact pits, indicating that the erosion process resulted in less damage to the substrate. The EDS results shows that superhydrophobicity plays a critical role in protecting the substrate from erosion. It is thus believed that the superhydrophobic surface has pronounced effects for improving the hardness and erosion resistance of Ti alloy.

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.

Droplet Spreading on Textured Surface Based on SPH Method

2013 ◽  
Author(s):  
Shuai Meng ◽  
Zhen Zhao ◽  
Qian Wang ◽  
Rui Yang
Keyword(s):  
Contact Angle ◽  
Water Drop ◽  
Particle Interaction ◽  
Textured Surface ◽  
Sph Method ◽  
Droplet Spreading ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
Main Effects

Droplet spreading occurs when a water drop hits the surfaces in a relatively low speed, which is a very important process in many applications (for example printing technologies and especially observation of diffusion of liquid state contaminant). This paper is aimed at analyzing contact angle and roughness, the two main factors’ effect on droplet spreading using SPH (smoothed particle hydrodynamics) method. When fluid-fluid and fluid-solid particle-particle interaction is added according to Alexandre Tartakovsky and Paul Meakin, surface tension and contact angle can be simulated. Line-shaped projections of different height are applied here as rough surfaces. The result shows two main effects of textured surface with different contact angle: unequal spreading in different direction and capillary phenomenon in the gap formed by the line-shaped projections.

Evaporative Characteristics of Al2O3 Nanofluid Droplet on Heated Surface

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Dae Yun Kim ◽  
Jae Bin Lee ◽  
Seong Hyuk Lee ◽  
Jung-Yeul Jung
Keyword(s):  
Contact Angle ◽  
Heated Surface ◽  
Dynamic Contact Angle ◽  
Average Diameter ◽  
Contact Angles ◽  
Textured Surface ◽  
Al2o3 Nanoparticles ◽  
Cnc Machine ◽  
Data Logger ◽  
Temperature Detector

The present study experimentally investigates the evaporative characteristics for a nanofluid droplet on heated surface. For experiments, the alumina (Al2O3) nanoparticles having a 50 nm average diameter were distributed in deionized (DI)water. The equilibrium contact angles (ECA) of DI-water on bare (without texturing) and hole-patterned textured (by µ-CNC machine) copper surfaces were 60o and 82o. Also, advancing and receding contact angles were 73.3o and 25.8o for bare surface, and 101.3o and 55.2o for textured surface. Surface temperature was fixed as 100±0.2oC, measured by resistance temperature detector (RTD) sensors with data logger. During the experiments, the ambient temperature was 22oC with the relative humidity of 32%. At the initial stage, the dynamic contact angle (DCA) of 0.01 vol.% nanofluid droplet on the textured surface drastically increased over its own ECA due to the generation of large bubbles inside the droplet. However, the contact angle of 0.1vol.% nanofluid droplet at t = 5 s was smaller than that of 0.01vol.% case because the increase in nanofluid concentration caused the reduction of surface tension. After that, DCA gradually decreased until dried out, and total evaporation time was significantly delayed in the case of textured surface. Moreover,the heat transfer characteristics during evaporation phenomenon was affected by the nanofluid concentration and the contact area with the heated surface.

Fabrication of superhydrophobic surface on AISI316L stainless steel using a nanosecond pulse laser

2021 ◽  
pp. 095440542110406
Author(s):  
Viboon Tangwarodomnukun ◽  
Supawan Kringram ◽  
Hao Zhu ◽  
Huan Qi ◽  
Nopporn Rujisamphan
Keyword(s):  
Contact Angle ◽  
Stainless Steel ◽  
Metal Surface ◽  
Pulse Laser ◽  
Laser Power ◽  
Superhydrophobic Surface ◽  
Ambient Air ◽  
Nanosecond Pulse ◽  
Textured Surface ◽  
Nanosecond Pulse Laser

Laser texturing process is a promising method to alter the wettability of metal surface on which micro/nano rough structures are created for changing the contact angle between the textured surface and liquid droplet. This paper aims at fabricating a superhydrophobic surface on AISI316L stainless steel, and a nanosecond pulse laser was employed for texturing line and point patterns on the metal surface. The influences of texturing patterns, laser power, scan speed, irradiation duration, and aging hours on the water contact angle and morphology of workpiece surface were investigated. According to the results, the hydrophilic surface was obtained right after the texturing process, and the surface turned to be hydrophobic after being left in ambient air for 15 days. The aging of laser-textured surface was also performed to induce the chemisorption of hydrocarbons toward the surface. This post process was able to shorten the hydrophilic-to-hydrophobic transition from days to a few hours. The aging duration of 2 and 0.5 h was respectively recommended for yielding and stabilizing the superhydrophobicity on line- and point-patterned surfaces. The maximum contact angle of 159.61° was achievable when the point pattern was textured on the stainless steel surface by using the laser power of 10 W and irradiation duration of 0.18 ms.

The Effects of Laser Texturing Parameters on Wear Properties of Rollers with Fractal Geometry

2008 ◽  
Vol 375-376 ◽  
pp. 328-332
Author(s):  
Hong Bin Liu ◽  
Da Ping Wan ◽  
De Jin Hu
Keyword(s):  
Fractal Dimension ◽  
Wear Rate ◽  
Power Density ◽  
Fractal Geometry ◽  
Laser Power ◽  
Processing Parameters ◽  
Laser Power Density ◽  
Textured Surface ◽  
Laser Texturing ◽  
Fractal Parameters

The processing parameters of laser texturing are linked with the wear property of roller surface based on the relationship between the fractal parameters and surface roughness. The influence of laser power density, scanning speed and pulse width on the roughness is analyzed though experiments. The effect of fractal parameters on the wear rate of the roller is analyzed with fractal geometry model for wear prediction. Condition of achieving engineering surface with optimal fractal dimension is presented and the expression of the optimal fractal dimension is derived. It shows that the roughness of laser textured surface and normalized wear rate are mainly determined by laser power density and fractal dimension, respectively. Moreover, to get the textured surface with smallest nominal wear rate, processing parameters of laser texturing, especially the laser power density, should be controlled properly besides the material properties of the roller. The result will provide guidance for the processing.

Sign in / Sign up

Export Citation Format

Share Document