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Drag reduction effect of ultraviolet laser-fabricated superhydrophobic surface
摘要： Superhydrophobic (SH) surface has been found effective for drag reduction in wall-bounded turbulence for decades, especially the metallic durable SH surfaces are believed very promising for improving the velocity and voyage of marine vehicles. We present stainless steel SH surfaces with U-groove patterns that fabricated by ultraviolet laser texturing and coating modifier treatment. The drag-reducing effects of the SH surfaces are tested by a self-built gravity sliding speed improving evaluation device. The results show that the different drag-reduction performance of the SH surfaces can be achieved by adjusting the line spacing of the crossing U-groove patterns. With the line spacing equalling to 80 μm, the ultraviolet laser textured stainless steel SH surface acquires the static contact angle of 161.5° and the dynamic sliding angle of only 2°, which leads to the maximum speed improving rate of 29.7%.
关键词： drag reduction,Superhydrophobic surface,stainless steel,laser texturing
更新于2025-09-23 15:23:52
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The interaction between the osteosarcoma cell and stainless steel surface, modified by high-fluence, nanosecond laser pulses
摘要： The irradiation of metallic surfaces by high-fluence laser pulses in an oxygen-containing atmosphere inevitably modifies the surface topography, chemistry, and wettability. These modifications significantly influence cell-surface interactions and, consequently, surface biocompatibility. We investigate how surface texturing by high-fluence nanosecond laser pulses from a Nd:YAG laser (wavelength of 1064 nm) influences cell adhesion and morphology with the aim of assessing its impact on initial cell behaviour. Quantitative and qualitative analysis of osteosarcoma cell adhesion, viability, and cell morphology were evaluated after 24-hour exposure to non-treated and laser-textured stainless-steel (AISI 316L) surfaces by fluorescent and scanning electron microscopy. The results reveal that this, initial interaction between the cells and the laser-textured surfaces leads to round shaped cells with a smaller footprint. Contrarily, on the non-processed stainless-steel and control-glass surfaces the polygonal, highly elongated, and flattened cells are observed. The cells on the laser-textured surfaces are less dendritic, with short tubular protrusions and an overexpression of extracellular vesicles, which are rarely found on non-treated and control samples. This likely happens due to the formation of nanostructured, high-temperature oxides that are induced by laser ablation. The analysis by X-ray photoelectron spectroscopy reveals that the laser-textured stainless-steel surfaces contain Cr hexavalent oxide, which is more toxic than the native oxide layer on the non-processed samples.
关键词： MG63 cells,cell adhesion,Laser surface engineering,laser texturing,nanosecond-laser ablation
更新于2025-09-23 15:21:01
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Design of Chemical Surface Treatment for Laser Textured Metal Alloy to Achieve Extreme Wetting Behavior
摘要： Extreme wetting activities of laser-textured metal alloys have received significant interest due to their superior performance in a wide range of commercial applications and fundamental research studies. Fundamentally, extreme wettability of structured metal alloys depends on both surface structure and surface chemistry. However, compared with the generation of physical topology on the surface, the role of surface chemistry is less explored for the laser texturing processes of metal alloys to tune the wettability. This work introduces a systematic design approach to modify the surface chemistry of laser textured metal alloys to achieve various extreme wettabilities, including superhydrophobicity/superoleophobicity, superhydrophilicity/superoleophilicity, and co-existence of superoleophobicity and superhydrophilicity. Microscale trenches are first created on the aluminum alloy 6061 surfaces by nanosecond pulse laser surface texturing. Subsequently, the textured surface is immersion-treated in several chemical solutions to attach target functional groups on the surface to achieve the final extreme wettability. Anchoring fluorinated groups (-CF2- and -CF3) with very low dispersive and non-dispersive surface energy leads to superoleophobicity and superhydrophobicity, resulting in repelling both water and diiodomethane. Attachment of polar nitrile (-C≡N) group with very high non-dispersive and high dispersive surface energy achieves superhydrophilicity and superoleophilicity by drawing water and diiodomethane molecules in the laser textured capillaries. At last, anchoring fluorinated groups (-CF2- and -CF3) and polar sodium carboxylate (-COONa) together lead to very low dispersive and very high non-dispersive surface energy components. It results in the co-existence of superoleophobicity and superhydrophilicity, where the treated surface attracts water but repels diiodomethane.
关键词： Design,chemical modification,laser texturing,superhydrophilicity,superoleophobicity,superhydrophobicity
更新于2025-09-23 15:21:01
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Influence of laser texturing on the wettability of PTFE
摘要： Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer showing excellent thermal and electrical insulation properties and a low coefficient of friction. Due to its large stability, and hydrophobic nature, the wettability of PTFE surfaces can be reduced to transform them into superhydrophobic. In this regard, laser texturing is a fast, simple and versatile method to produce superhydrophobic PTFE surfaces in one-step, and over large areas. In this work, we used a CO2 laser to modify the surface of PTFE samples. We studied the effect of the processing parameters (laser power or irradiance, scanning speed, and spacing -overlapping- between scan lines) on the wettability of textured surfaces using water, mineral oil and ethanol/water solutions as test fluids. Laser-treated surfaces showed a hierarchical micro- and nanotopography with a cotton-like appearance. The higher roughness and large quantity of air pockets make these laser-treated surfaces superhydrophobic, and highly oleophobic. Furthermore, they remain unaltered after being in contact with strong alkali and acid solutions or after slight friction. The self-cleaning performance of these surfaces was also demonstrated. The present findings suggest that CO2 laser texturing of PTFE is suitable for the large-scale preparation of surfaces with low-wettability to different liquids.
关键词： Polytetrafluoroethylene (PTFE),self-cleaning,wettability,laser texturing
更新于2025-09-23 15:19:57
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Surface functionalization by nanosecond-laser texturing for controlling hydrodynamic cavitation dynamics
摘要： The interaction between liquid flow and solid boundary can result in cavitation formation when the local pressure drops below vaporization threshold. The cavitation dynamics does not depend only on basic geometry, but also on surface roughness, chemistry and wettability. From application point of view, controlling cavitation in fluid flows by surface functionalization is of great importance to avoid the unwanted effects of hydrodynamic cavitation (erosion, noise and vibrations). However, it could be also used for intensification of various physical and chemical processes. In this work, the surfaces of 10-mm stainless steel cylinders are laser textured in order to demonstrate how hydrodynamic cavitation behavior can be controlled by surface modification. The surface properties are modified by using a nanosecond (10–28 ns) fiber laser (wavelength of 1060 nm). In such a way, surfaces with different topographies and wettability were produced and tested in a cavitation tunnel at different cavitation numbers (1.0–2.6). Cavitation characteristics behind functionalized cylindrical surfaces were monitored simultaneously by high-speed visualization (20,000 fps) and high frequency pressure transducers. The results clearly show that cavitation characteristics differ significantly between different micro-structured surfaces. On some surfaces incipient cavitation is delayed and cavitation extent decreased in comparison with the reference – a highly polished cylinder. It is also shown that the increased surface wettability (i.e., hydrophilicity) delays the incipient cavitation.
关键词： Surface engineering,Laser texturing,Hydrodynamic cavitation,Fluid dynamics,Hydrophobic/hydrophilic surface
更新于2025-09-23 15:19:57
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Laser Micro-Texturing of Sintered Tool Materials Surface
摘要： The purpose of this paper is to show the effect of tool materials surface treatment while using laser texturing on the structure and properties of cemented carbides and sialon ceramics. The tests were made on multi-point inserts subjected laser texturization and honeycomb-like texture was obtained. Comprehensive investigations in the scanning electron microscope (SEM) were made. Morphology was examined by the use of atomic forces microscope (AFM) and confocal microscope. The chemical composition of the tested materials using energy-dispersive X-ray spectrometer (EDS) was investigated. Moreover, exploitative properties, including wear resistance using the "pin on disc" method and roughness, were also tested. It was found that the laser texturing provides a suitable modification of the structure improving tribological properties. Tests suggest that laser texturing can contribute to the durability of cutting tool’s edge, which qualifies this type of surface treatment for wide industrial applications.
关键词： Laser Induced Periodic Surface Structures (LIPSS),cemented carbides,laser texturing,sialon tool ceramics
更新于2025-09-19 17:13:59
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Roughness and wettability properties of plain and silica-coated copper surfaces textured with picosecond laser
摘要： Many recent studies have investigated the mechanism of wettability transition of laser-textured copper surfaces on di?erent materials. Furthermore, several such studies have focused on approaches to accelerate wettability transition from hydrophilicity to hydrophobicity, such as temperature annealing and the use of chemical solutions. However, few researchers have focused on maintaining the initial hydrophilicity of laser-textured surfaces. This study presents a hybrid surface modi?cation method involving chemical bath deposition and ultrafast laser. First, the selected copper substrates are modi?ed using the sol-gel method through dip coating. Subsequently, the coated copper surfaces are irradiated with a picosecond laser. After laser texturing, bumpy structures are formed, and SiO2 nanoparticles can be sintered on the surfaces. Thus, the original hydrophilicity can be maintained, and the surface roughness can be enhanced simultaneously. By using this hybrid modi?cation method, a heterogeneous surface with high-precision patterns can be obtained. Moreover, the mechanism of wettability transition of laser-textured copper surfaces with di?erent laser ?uences is discussed using the Wenzel and Cassie Baxter wetting model by analyzing the chemical composition and surface morphology of the treated surfaces.
关键词： Roughness,Copper,Laser texturing,Wettability,Picosecond laser,Sol-gel
更新于2025-09-19 17:13:59
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A Study on the Effect of Ultrashort Pulsed Laser Texturing on the Microstructure and Properties of Metastable S Phase Layer formed on AISI 316L Surfaces
摘要： Austenitic stainless steels (ASS) are an important material within the food and medical industries. However, their current limitations of poor wear resistance and susceptibility to bacterial colonisation have limited further uptake. Low-temperature plasma nitriding can address the poor durability of the ASS alloys by forming the S phase, therefore, providing combined improvement in hardness, wear resistance and corrosion resistance. Additionally, pulsed laser texturing can also be used to introduce functional antibacterial textures. However, due to the thermal nature of laser patterning and the thermodynamic metastability of the S phase, almost no research has been conducted thus far on combining the technologies. Therefore, this study for the first time has investigated the response of S phase treated surfaces to ultrashort (nano and femtosecond) laser texturing. The results have shown that, both theoretically and in practice, laser pulses within the nanosecond regime led to the damage of the surface, decomposition of the metastable S phase and loss of the corrosion resistance. In contrast, no change of the S phase surface layer could be detected following femtosecond laser texturing. Hence, demonstrating the feasibility of texturing S phase surfaces using femtosecond pulsed lasers, thus paving the way towards long-lasting multi-functional antibacterial stainless steel surfaces.
关键词： low-temperature nitriding,active-screen plasma,S phase,AISI 316L,thermal stability,pulsed laser texturing
更新于2025-09-19 17:13:59
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Effect of laser texturing on the surface characteristics and bonding property of 30CrMnSiA steel adhesive joints
摘要： The influence of laser texturing on the bonding property of 30CrMnSiA steel joints were investigated. Three patterns including dimple, groove and grid were laser textured on the 30CrMnSiA steel substrate by nanosecond fiber laser. The processed surface was characterized by surface morphology, surface roughness (Ra and Rz) and wettability. The single lap adhesive joints were fabricated and fracture surfaces were observed. The accelerated hygrothermal aging experiments were performed. The results indicated that surface roughness and wettability were both enhanced after laser texturing. The grid patterned substrate was improved pronouncedly, where Ra increased by 400% and Rz was 13 times higher than as-received specimens, and the contact angle was decreased from 65° to 24°. The shear strength of adhesive joints for dimple pattern was not improved evidently, while it was 14.6 MPa and 23.3 MPa in the groove and grid patterned specimens, which was increased by 219%, 348% compared to as-received ones, respectively. The coverage of adhesive layer on the fracture surface was increased and the fracture mode of dimple and groove patterned specimens was adhesive failure and a cohesive failure was achieved for those joints with grid pattern. The bonding property was decreased after hygrothermal aging, and the residual strength of specimens with grid pattern was the highest. The fracture mode was not changed in all adhesive joints.
关键词： Laser texturing,Wettability,Roughness,Adhesive strength,Hygrothermal aging
更新于2025-09-19 17:13:59
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Quadri-directionally anisotropic droplets sliding surfaces fabricated by selective laser texturing of aluminum alloy plates
摘要： A periodic array patterned superhydrophobic surface consisted of asymmetric multi-directional stairway units was prepared by selective laser texturing of aluminum alloy plate, which was endowed for the first time with the quadri-directionally anisotropic droplets sliding characteristic. Through the layer-by-layer subtractive laser ablation procedure, the unique unequal tread depths of the micron-sized stairway-structure in four directions were ingeniously constructed. The achieved surface with an arbitrary desired sliding angle in any of the four directions constructed a transitional superhydrophobic state between Wenzel’s and Cassie’s states of the supported water droplets. The comprehensive mechanism of the supernatural quadri-directional anisotropy was verified to be mainly summarized into the synergy and balance between the droplet’s resistance effect of gravity force and the pinning-effect controlled adhesion force. The two obstructive effects were verified to be in exact accordance with each other on the movement of water droplets. The quadri-directionally anisotropic sliding droplets characteristic induced by the simple but powerful selective laser texturing method can provide a fresh cognition of anisotropic wettability and enormous potential applications in microfluidic systems for biochemical separation.
关键词： Laser texturing,Anisotropic droplets sliding,Quadri-directional,Superhydrophobic
更新于2025-09-19 17:13:59