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This paper deals with the influence of laser surface texturing on tribological performance of two different tool steels: (a) Böhler K100 produced by conventional production technology and (b) Böhler K390 Microclean® produced by powder metallurgy. The surface of heat-treated tool steels was modified using three different texture patterns. Impact of laser surface texturing was analyzed after different treatments. Furthermore, selected samples were borided to evaluate the combined influence of laser surface texturing and boriding on tribological performance of surface-treated samples. The results show that boriding was not beneficial for wavy surface type, and the steel production technology had a certain influence on the spinning tool. The laser surface texturing had an effect on decreasing the coefficient of friction on the K100 tool steel; however, it did not influence the tribological performance of the K390 Microclean® tool steel. Boriding process was efficient in decreasing the coefficient of friction for both steels. The low coefficient of friction values did not have a positive influence on the wear depth. [ABSTRACT FROM AUTHOR]

Micro-textures on cutting tool surface have been reported for their benefits in terms of reduction of adhesion, wear, force and friction during the cutting process. However, these benefits are dependent on the micro-texture parameters. This paper presents an experimental study on the effect of micro-textures during orthogonal cutting of aluminium, aiming to determine a suitable parameter combination. Micro-textures were fabricated on the rake face of tungsten carbide (WC) cutting tools by a picosecond laser. Circular dimples were selected as the texture unit cell, and the parameters included diameter, depth, pitch and distance from the cutting edge. Experiments were conducted by varying these parameters using the Taguchi method. Signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were used to find the optimal levels of the selected parameters and to study the effect of the micro-textures on cutting forces, shear angle, contact area as well as adhesion of aluminium. It is found that diameter was the most influential parameter based on the factors taken into consideration. Then, a confirmation test using the derived levels of texture parameters was carried out to demonstrate the effectiveness of the micro-texture. The best combination of texture parameters was identified considering all the responses and the range of parameters. [ABSTRACT FROM AUTHOR]

The unfavorable environmental conditions of certain tribological systems, such as operation at high temperatures or under vacuum, set the need to replace liquid with solid lubricants. Multi-Wall-Carbon Nanotubes (MWCNTs) have been emphasized as a very effective solid lubricant. The particles have been used to create self-lubricating materials by acting as reinforcement phase in composites or as solid-lubricant coating that works in conjunction with textured surfaces to prevent the removal of particles from the contact. However, both approaches are restricted to some extent. In the case of composites, the solid lubricant concentration is limited so as not to influence the mechanical stability of the final component. For coated surface structures, the textured surfaces can degrade during the experiment. The present study focuses on the combination of these approaches in order to create enhanced self-lubricating surfaces with MWCNTs as the solid lubricant. A custom-made ring-on-block tribometer is used to study the behavior of laser textured MWCNT-coated and MWCNT-reinforced nickel matrix composites under the conditions of unidirectional sliding in conformal contact. It is shown that the combination of both approaches allows for a maximum 4-fold reduction in friction and a 115-fold reduction in wear rate compared to the reference. Additionally, the lubrication mechanism of the MWCNTs is investigated in more detail and a structural degradation model of the mechanically stressed MWCNTs is proposed. Our results highlight the integrated solution as a suitable approach for self-lubricating surfaces subjected to unidirectional sliding. [ABSTRACT FROM AUTHOR]

The aim of this work is to present the effect of synergy interaction hybrid surface treatment of tool ceramics using methods of CVD chemical coating deposition and selective laser texturing on the structure and properties of obtained hybrid surface layer. Comprehensive research results in scanning electron microscopy (SEM), morphology with atomic force microscope (AFM) as well as chemical composition of produced coatings with EDS scattered energy spectrometer are presented. Exploitative properties, including adhesion with the "scratch test" method, wear resistance using the "pin on disc" method, roughness were also tested. As a result of the research, it was found that the creation of a hybrid layer of the CVD coating/laser texturing on the tool ceramics contributes to the improvement of the exploitative properties of the tested material. The honeycomb texture (in the micro-scale) created as a result of the selective laser treatment with the nanoripples (in nano scale) causes a decrease in the friction coefficient and the width and depth of the wear. Nanoripples LIPSS are a barrier to the damage propagation in the coating after exceeding the critical load confirmed during the adhesion tests. [ABSTRACT FROM AUTHOR]

The model of ball-on-disk test was established and three kinds of textures with different geometric characteristics were designed on the surface of the cemented carbide disk. The optimal geometric characteristic of texture was obtained by finite element analysis. The hole-textures of different parameters were processed on the surface of the cemented carbide disk by laser machining. The effects of texture and lubricant on friction and wear behaviour were analysed by comparing four different cemented carbide disks through the ball-on-disk contrast tests. Ball-on-disk orthogonal tests were carried out to obtain the best geometric parameters of the hole-texture. The results of numerical simulation showed that the wear depth of the hole-texture disk was the smallest among all three different textured disks. The results of contrast tests showed that the texture filled with lubricant could effectively improve the friction and wear of cemented carbide disk in dry sliding against TC4 titanium alloy balls. It was found that the adhesion of the surface textured cemented carbide disk was the most serious and the adhesion of the surface textured cemented carbide disk with lubricant filled into the textures was the lowest among four tested samples, which indicated that the texture could significantly increase the adhesion of titanium alloy to the surface of cemented carbide disk, while the solid lubricant could effectively reduce it. Meanwhile, the main effect mechanisms of textures were also discussed. In addition, the best geometric parameters of the texture were determined to be 100 μm in diameter, 80 μm in depth and 600 μm in spacing through orthogonal tests. It was also found that the spacing had the greatest effect on the friction coefficient and the wear volume, and the friction coefficient and the wear volume decreased with the increasing of the spacing. [ABSTRACT FROM AUTHOR]

Zirconium nitride is used as a selective surface for concentrated solar heating applications and one of the methods to form a zirconium nitride is texturing of zirconia surface by a high intensity laser beam under high pressure nitrogen gas environment. Laser texturing also provides hydrophobic surface characteristics via forming micro/nano pillars at the surface; however, environmental dust settlement on textured surface influences the surface characteristics significantly. In the present study, laser texturing of zirconia surface and effects of the dust particles on the textured surface in a humid air ambient are investigated. Analytical tools are used to assess the morphological changes on the laser textured surface prior and after the dust settlement in the humid air ambient. It is found that laser textured surface has hydrophobic characteristics. The mud formed during condensate of water on the dust particles alters the characteristics of the laser textured surface. The tangential force required to remove the dry mud from the textured surface remains high; in which case, the dried liquid solution at the mud-textured surface interface is responsible for the strong adhesion of the dry mud on the textured surface. The textured surface becomes hydrophilic after the dry mud was removed from the surface by a desalinated water jet. [ABSTRACT FROM AUTHOR]

The photovoltaics market has been growing rapidly in the past decade or so, driven by policy support, growing economies of scale, and technological improvements. Continued advances in photovoltaics manufacturing and technologies may drive further cost reductions and facilitate market growth going forward. Here, we review one such potential advance: the use of ultrafast laser processing in silicon photovoltaic production. We provide an overview of the current major capabilities of ultrafast laser processing of silicon, including texturing, hyperdoping, and combined texturing and hyperdoping. We describe each process, survey recent advances, compare to alternative methods, and report the state-of-the-art of each process in relation to photovoltaic devices. We also discuss the major challenges facing each process. We close with a prospectus for research and applications. We conclude that there are no major technical obstacles to the application of ultrafast laser texturing to photovoltaics manufacturing currently, while ultrafast laser hyperdoping requires further research and development before adoption. We also show that the use of hyperdoping for intermediate band silicon photovoltaics likely requires concurrent surface texturing or other absorption-enhancement techniques to yield photoconversion efficiency improvements. [ABSTRACT FROM PUBLISHER]

The study of surface texturing on a metallic surface has become a great area of interest of researchers in the last few decades. Surface texturing is employed for enhancing the performance of the surface in its working environment. As the characterization techniques have been evolving very fast, researchers have started mimicking the natural surfaces to take the advantages of their characteristics (such as self-cleaning, load capacity, reducing coefficient of friction). Manufacturing of natural inspired surface requires having a great control over the process to achieve the micro or nano features on the natural surfaces. Hence, the selection of the most suitable process and optimum parameters for machining of arrays of micro or nano features at large scale is highly desirable. This study reports an overview of different micromachining processes used for texturing on metallic surfaces and research gaps to be filled in the available literature. Electrochemical micromachining has tremendous potential on account of its versatility in different applications. It is a promising and economically viable machining process for micromanufacturing industries for fabrication of micro textures and micro features on metallic surfaces. Production of textured surface at large scale requires a sustainable technology, which can serve the purpose of enhancing the performance of the surface without changing the original properties of the surface. Indeed, laser surface texturing, through-mask electrochemical micromachining, lithography, micro- or nanocasting and so on are the existing methods which involve multiple steps for generation of textured surfaces. This article also reports some original experimental investigations for generation of different kinds of micro textures on metallic surfaces, namely, arrays of micro dimples, micro channels and micro pillars using a single-step maskless electrochemical micro-texturing process with a pre-patterned micro tool. [ABSTRACT FROM AUTHOR]

Abstract: This work presents a novel texture design for implants surface functionalization, through the creation of line‐shaped textures on Ti6Al4V surfaces and subsequent sintering of hydroxyapatite (HAp) powder into the designated locations. HAp‐rich locations were designed to avoid HAp detachment during insertion, thus guaranteeing an effective osseointegration. This process starts by creating textured lines using a Nd:YAG laser, filling these lines with HAp powder and sintering HAp using a CO2 laser. The adhesion of HAp is known to be influenced by HAp sintering parameters, especially laser power and scanning speed and also by the textured lines manufacturing. Different laser parameters combinations were used to assess the sintering and adhesion of HAp to the textured lines. HAp adhesion was assessed by performing high energy ultrasonic cavitation tests and sliding tests mimicking an implant insertion, with Ti6Al4V/HAp specimens sliding against animal bone. The HAp content retained after these tests was measured and results showed that an excellent HAp sintering and adhesion was achieved when using a scan speed of 1 mm/s and laser power between 9 and 9.6 W. It is important to emphasize that results indicated that the HAp bioactivity was maintained when using these conditions, validating this functionalization process for the production of hip prosthesis with improved bioactivity. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1534–1545, 2018. [ABSTRACT FROM AUTHOR]

In the present work, the authors study the tribological characteristics of textured stainless steel surfaces with different texture depths ranging from 1.3 to 23 µm created by laser surface texturing and ultra‐precision diamond cutting. The periodicity of the surface textures is kept constant at 90 µm for each fabrication technique and texture depth. Subsequent ball‐on‐disk friction tests show that friction and wear can be effectively reduced by the surface texturing. It is found that the effectiveness of the surface textures greatly depends on the depth and the geometry of the textures, as well as on testing parameters such as the applied load and the sliding velocity. Surface textures with the lowest depth demonstrate a slightly increased COF as well as an increased mass loss under low loads or sliding velocities. On the other hand, surface textures with intermediate depths show a significant reduction in the COF and wear. The observed friction and wear reduction can be mainly attributed to a combined effect of the surface textures consisting of the generation of an additional hydrodynamic pressure, the storage of produced wear particles as well as the action as secondary source for lubricant (reservoir effect). [ABSTRACT FROM AUTHOR]

Thermal barrier coating systems are usually build-up with bond coats to ensure a good adhesion of the ceramic top coat and to protect the substrate against oxidation and corrosion. Such system is often subjected to complex thermo-mechanical loading. Because of the very different damage processes encountered during service operations, a simplified system was investigated by removing the bond-coat. Recently adhesion bond strength was enhanced using laser surface texturing of the substrate in thermal spraying processes. Atmospheric plasma spray yttria-stabilized-zirconia thermal barrier coating system was deposited on the Ni-based AM1 single crystalline superalloy without bond coat. Adhesion bond strength was already increased compared to conventional processing method. Top coat durability was evaluated at high temperature and damage mechanisms were studied. Isothermal and cyclic oxidation tests showed durability of 1000 h and 400 cycles at 1100 °C. The oxidation mechanisms at the substrate/top coat interface changed due to fast solidification during the laser texturing process. Then, TBC system was studied under high temperature mechanical solicitation in tension creep. The textured interfaces were not damaged after 1% creep strain while top-coat/substrate interfacial cracking was observed for grit-blasted specimens. Moreover, no preferential crack development in the substrate was observed. Patterns provided an enhanced adhesion by changing the stress distribution near the interface. [ABSTRACT FROM AUTHOR]

In the present work, pulsed laser assisted texturing of the piston ring and its influence on tribology characteristics were studied experimentally and theoretically. Influence of laser wavelengths of 532 nm and 1064 nm on surface morphology of dimples, formed on the piston ring samples was studied. Subsequently, the laser wavelength of 532 nm was used for texturing to generate dimples with different sizes, aspect ratio and area density. Tribological characteristics of textured samples consisting of dimples with size, aspect ratio and area density ranging from 40 μm to 130 μm, 0.1 to 0.3 and 5% to 38%, respectively were measured experimentally by using reciprocating tribometer. The results showed that the aspect ratio concerning minimum friction varied with dimple size. The results also indicated that the area density of 16% showed low friction compared to other fractions for all the dimple diameters considered for the analysis. A reduction in cylinder liner wear rate of 72% was observed when tested with textured ring sample of the desired dimension compared to the liner tested with the non-textured ring. A theoretical model based on Reynolds equation was used to determine lubricant film thickness between textured surface and a non-textured counter surface. The experimental studies on friction coefficient were then compared with the theoretical results on film thickness. [ABSTRACT FROM AUTHOR]

The current work focused on the development of hydroxyapatite (HAP) coating on laser textured metallic implants using electrophoretic deposition. HAP was synthesized by sol-gel technique and its phase purity and surface morphology were confirmed by FT-IR, XRD and SEM analysis. 316 L SS and Ti-6Al-4V metal implants were polished and the surface was modified using Nd-YAG laser operating at a pulse interval of 10 ns at various overlapping rate of 0%, 25% and 50%. The laser treated surface was characterized for its surface roughness using surface profilometry and surface morphology. The surface roughness of the metallic implants was increased by increase in the overlapping rate. The prepared HAP powder was electrophoretically deposited on bare and laser textured Ti-6Al-4V and 316 L stainless steel followed by vacuum sintering at 300 °C for 2 h. Scratch analysis results showed an improvement in adhesion strength for the HAP coatings on laser treated specimens than untreated metal. Corrosion efficiency of the coated samples was studied in SBF solution using EIS and potentiodynamic polarization studies. The result from the corrosion experiments proved increased corrosion resistance property of laser textured coated samples when compared to bare alloy due to higher adhesion of HAP coating on the metal surface. [ABSTRACT FROM AUTHOR]

Ti6Al4V samples with micro-dimple arrays were subjected to laser shock peening in contact with foil (HCLSP). The surface roughness, micro-hardness, the residual stress distribution and the surface morphology of the micro-dimple arrays were studied to evaluate the effects of HCLSP. Moreover, the surface topography of the foils in contact was also analyzed. The gap existence between the foil and the to-be treated surface led the mechanism of HCLSP to be different compared to regular laser shock peening. The surface roughness reduction, the work-hardening effects, the compressive residual stress and the micro crack enclosure were achieved. A simplified ball-hitting-surface model was utilized to analyze the HCLSP impact. The model could well explain the experimental results. When treated by the HCLSP with H62 foil at the laser power density of 4.24 GW/cm 2 , the Ti6Al4V samples with micro-dimple arrays exhibit well surface topography and mechanical performance. [ABSTRACT FROM AUTHOR]

Laser texturing of carbon steel surfaces is carried out under the high pressure N2 assist gas. The morphological and metallurgical changes in the laser treated layer are examined. The hydrophobic characteristics of the laser textured surfaces are assessed incorporating the water droplet contact angle measurement method. It is found that laser treated surfaces composes of micro/nano textures with the average surface roughness (Ra) in the order of 2.4 μm. The combination of evaporation and melting at the irradiated spot reduces the texture height and surface roughness. The presence of closely spaced laser scanning tracks generates self-annealing effect in the treated layer while modifying the thermal strain in this layer. Laser textured surface demonstrates hydrophobic characteristics and some small variation of water droplet contact angle is observed because of non-uniform texture distribution at the surface; nevertheless, this variation is small. [ABSTRACT FROM AUTHOR]

Hydrophobic surface on brass has attracted intensive attention owing to its importance in scientific research and practical applications. Laser texturing provides a simple and promising method to achieve it. Reducing wettability transition time from hydrophilicity to hydrophobicity or superhydrophobicity remains a challenge. Herein, wettability transition of brass surfaces with hybrid micro/nano-structures fabricated by laser texturing was investigated by immersing the samples inside different mediums. Scanning electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy and surface contact angle measurement were employed to characterize surface morphology, chemical composition and wettability of the fabricated surfaces of brass samples. Wettability transition time from hydrophilicity to hydrophobicity was shortened by immersion into isopropyl alcohol for a period of 3 h as a result of the absorption and accumulation of organic substances on the textured brass surface. When the textured brass sample was immersed into sodium bicarbonate solution, flower-like structures on the sample surface played a key role in slowing down wettability transition. Moreover, it had the smallest steady state contact angle as compared to the others. This study provides a facile method to construct textured surfaces with tunable wetting behaviors and effectively extend the industrial applications of brass. [ABSTRACT FROM AUTHOR]

Cold spray is a technique allowing the deposition of metallic powders on several different substrates. The deposition process is ruled by different factors, among these, of particular interest are the superficial roughness and texturing of the substrate. The aim of this research was to study the influence of different superficial texturing on the deposition process of aluminium powders on an AA 2024 T3 plate. Samples with different superficial texturing were produced by laser engraving through a Yb:YAG fibre laser, varying the laser treatment parameters. Aiming to highlight the influence of the laser treatment, the deposition process was carried out on all the samples under the same spraying condition. The cross-section of the interface between the substrate and the coating and the microstructure of the coating itself were observed to study the influence of the superficial texturing on the coating formation. It was found that the superficial texturing influences both the adhesion mechanism and the microstructure of the coating. [ABSTRACT FROM PUBLISHER]

Surface engineering is widely used in different areas, such as the aerospace industry or the biomechanical and medical fields. Specifically, laser surface modification techniques may obtain specific surface finishes for special applications. In texturing laser procedures, the control of processing parameters has a great influence on the geometry and characteristics of the treated area. When these processes are carried out on titanium alloys, thin oxide layers are usually developed on the irradiated surface, formed through the thermochemical combination of vaporized material with atmospheric oxygen in the air. In thermal oxidation treatments of Ti6Al4V, the highest concentration of oxides is mainly composed by rutile (TiO2), producing surface property modifications such as hardness, among others. In this research, a thermochemical oxidation of Ti6Al4V alloy has been performed through laser texturing, using laser scanning speed (Vs) and pulse rate (f ) as process control variables, and its influence on the beam absorption capacity of the modified layer have been analyzed. Combined evaluations of microgeometrical features and mechanical properties, such as hardness, verified that, by means of laser texturing treatments, the ability to generate specific topographies and increase the initial hardness of the alloy is obtained. The most advantageous results for the increase of hardness by thermochemical oxidation have been detected in low scan speeds of laser beam treatments, resulting in an increase of approximately 270% using a scanning speed of 10 mm/s. On the other hand, a dependence between roughness values, in terms of Ra and Rz, and the energy density of pulse (Ed) has been observed, showing higher values of roughness for a 17.68 J/cm2 energy density of pulse. [ABSTRACT FROM AUTHOR]

The influence of the clamping frame material in Friction Assisted Joining of polymer-metal sheets is investigated. An experimental campaign was conducted by varying the clamping frame material (steel and wood) and the heating time. The process was applied to join Al-Mg aluminum alloy and Polyvinyl Chloride sheets. Thermal analysis and energy measurements were conducted during the process. The morphology, fracture surface and strength of the joints were analyzed. The clamping frame made of wood enabled different advantages to be achieved, including reduction of the energy loss towards the clamping frame, faster heating of the materials being joined, and more uniform distribution of the temperature over the joining area, which resulted in increased mechanical strength. Under optimal conditions the joint efficiency approached 97%. [ABSTRACT FROM AUTHOR]

Poly-ether-ether-ketone (PEEK) is a thermoplastic polymer marked by high mechanical properties and chemical inertia. PEEK is also a well-known biomaterial which has been subjected to intensive research over the last decades. In particular, it has recently been shown that laser surface texturing as well as diamond-like carbon (DLC) film deposition was able to reduce PEEK wear in tribological testing. This study focuses on evaluating the mechanical and tribological performance of PEEK surfaces modified via laser surface texturing (LST) combined with DLC coating. An ultrashort-pulse laser was used in order to pattern a hexagonal array of 33 μm in diameter dimples onto the PEEK surface. The depth of dimples was varying (2, 12 and 21 μm) as well as the dimple density (10, 30 and 48%). Subsequently, a 2-μm thick DLC film was deposited on the textured PEEK surface. It was shown that LST did not significantly affect the DLC/PEEK adhesion in pull-off testing, however, deep dimples and high dimple densities led to a large deformation of the substrate and caused the film to be more susceptible to cracking in scratch testing. The DLC-coated LST PEEK surfaces were rubbed against an alumina ball in dry conditions, water and bovine calf serum solutions. DLC-coated PEEK with shallow dimples and a low dimple density enabled to significantly, reduce wear and friction in distilled water and reduce wear in bovine calf serum compared with smooth DLC-coated PEEK. Smooth and LST DLC films exhibited a great stability in terms of microstructure and chemistry in all tested media. [ABSTRACT FROM AUTHOR]

The present investigation aimed to determine the influence of the texturing strategy on the mechanical behavior of metal-polymer hybrid joints made by friction-assisted joining. An experimental campaign was conducted on AA7075 aluminum alloy and PolyEther Ether Ketone (PEEK). Laser texturing was performed on the aluminum surface before joining to improve the mechanical interlock between the substrates. Different laser texturing conditions were used by varying the number of scans and the distance between consecutive laser tracks. Microscopic analysis was conducted on the treated samples to determine the main geometrical characteristics. Single-lap shear tests were performed to determine the mechanical behavior of the produced connections. Fracture surface analysis was also performed to establish the main failure mechanisms. According to the achieved results, the laser texturing strategy significantly influenced the mechanical behavior of the joints, the peak force, the absorbed energy, and the failure mode. The density of the laser texturing affected the stress on the aluminum protrusions and the mechanical behavior. Adopting a higher number of scans improved the mechanical interlock and, consequently, the mechanical behavior of the joints. [ABSTRACT FROM AUTHOR]

Different kinds of materials are broadly employed to manufacture bioimplants. Metals are commonly used for the fabrication of lower body components such as knee prostheses and hip replacements because of their good mechanical properties. Among the available metallic biomaterials, cobalt alloys are commonly used. However, the hostile environment of the human body promotes the corrosion of the metallic bioimplant, and the wear due to the sliding contact could also increase the corrosion. There is, therefore, a constant attempt to study the surface of metallic biomaterials to enhance their functionality. In the present work, two kinds of surface modification techniques were employed on ASTM F-1537 cobalt alloy samples: laser surface texturing and boriding. Tribocorrosion tests were carried out using a linear reciprocating tribometer coupled with a standard three-electrode electrochemical cell. Tafel polarization plots were used to calculate the material loss due to corrosion. Also, non-contact profilometry was employed to estimate the tribocorrosion volume loss. In addition, the worn tracks were analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The textured + borided samples increased 1.5 times the tribocorrosion resistance compared to the untreated samples. The differences in the tribocorrosion performance among the modified surfaces were discussed in this paper. • The texturing and boriding increased the tribocorrosion resistance of the surface. • The material loss due to corrosion was lower than the material loss due to tribocorrosion. • The texturing decreased the real contact area and the boriding retarded wear. [ABSTRACT FROM AUTHOR]

[Display omitted] • Annealing treatment was used as an auxiliary method, which combined with femtosecond laser and stearic acid modification to prepare superhydrophobic samples, providing an auxiliary method for the preparation of superhydrophobic materials. • The formation mechanism of superhydrophobic surface was systematically studied. • The prepared surface has excellent wear resistance stability. • The prepared surface has excellent corrosion resistance. • The prepared surface does not introduce any toxic substances and can be used in the field of medical devices. Nitinol shape memory alloys are widely used in medical devices due to their special properties. However, the release of nickel ions into human liquid during corrosion process would cause great harm to human body. It has been found that super-hydrophobic surface with superior anti-corrosion performance could greatly solve this issue. Therefore, the preparation of green and healthy super-hydrophobic layer on nickel-titanium alloy surface has significant medical value. In this work, we explored a newly method of fabricating healthy super-hydrophobic surface with contact angle (WCA) of 153.2° ± 1.5°, and roll angle (RA) of 6° ± 0.5°by combination of nitinol alloy laser irradiation. Particularly, high temperature annealing was firstly adopted in the fabrication procession of super-hydrophobic surface, which can bring great reference value to the research in this filed. Besides, the formation mechanism was also revealed via the analysis of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Furthermore, corrosion behavior was also investigated by electrochemical impedance (EIS) analysis to illustrate preventing nickel ions release performance. Unlike the traditional super-hydrophobic surface preparation methods, this method does not introduce any toxic substances, which has great application prospects in the medical field. [ABSTRACT FROM AUTHOR]

WC10Co4Cr and WC10Co4Cr + (2 %, 3 %, 4 %) graphene nanoplatelets (GNPs) coatings were applied on laser-textured (circular shape: 100 μm in diameter and 200 μm in pitch) IS-2062 steel using the HVOF technique. The surface morphology of coated and uncoated surfaces was investigated using SEM, XRD, and EDS prior and after electrochemical corrosion tests in 3.5 % NaCl solution at room temperature. The results show that the coating binder (Co and Cr alloys) breaks down in NaCl solution, leading to localized pitting corrosion on the surface. The addition of GNPs to WC10Co4Cr coating powder improved the surface's corrosion resistance and reduced the emergence of localized pits. The WC10Co4Cr + 2%GNPs-coated substrate exhibited the lowest corrosion rate of (0.078361 mm/year) compared to other coatings and pristine substrate with the highest corrosion rate of (0.70679 mm/year). [Display omitted] • The addition of GNPs to WC10Co4Cr powder, corrosion resistance improved and reduced the emergence of localised pits. • The corrosion rate of IS-2062 steel was found to be 0.70679 mm/year, which is improved by WC10Co4Cr + 2%GNPs coating configuration. • GNPs particles acts as solid lubricant during scratch testing. • Laser texturing improved the mechanical interlocking of deposited coating. [ABSTRACT FROM AUTHOR]

Stainless steel substrates were textured with a checkboard pattern by a NIR laser with different scan pitches and laser powers. The as-textured surfaces were found to be hydrophilic. However, after holding in air for 7–15 days, the surfaces exhibited strong superhydrophobicity with contact angles close to 150° due to a reduction in the oxygen content. Thin-film Ag, Cu, Zn and Al coatings were deposited on the textured surfaces. The as-sputtered Ag and Cu films improved the hydrophobicity of the as-textured surface. However, the as-sputtered Zn and Al coatings increased the hydrophilicity. For all of the coatings, the hydrophobicity improved after aging in air for 7– 15 days. Furthermore, all of the coatings enhanced the corrosion resistance of the textured surface. Overall, the results indicate that laser texturing followed by thin-film metal deposition provides a feasible means of tuning both the wettability and the corrosion resistance of stainless steel surfaces. • The as-textured stainless steel surfaces were found to be hydrophilicby laser modification process. • After holding in air for 7–15 days, the surfaces exhibited strong superhydrophobicity with contact angles close to 150°. • Two processes (texture and metal coating) improved the hydrophobicity of the as-textured surface. • All of the coatings enhanced the corrosion resistance of the textured surface. [ABSTRACT FROM AUTHOR]

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.

Titanium dioxide and vanadium oxides have been applied extensively in industrial and medical fields. The objective of this study was to develop various composite structures of titanium and vanadium oxide (Ti-V-O) coatings on pure titanium through high-temperature annealing and laser texturing oxidation, separately; additionally, surface morphologies, tribological and hydrophilic properties, and antibacterial and biocompatibility abilities of these Ti-V-O coatings were evaluated. TiV alloy thin films were deposited on pure titanium and then annealed to form Ti-V-O coatings through thermal oxidation and laser texturing oxidation. Ball-on-disc wear tests and contact angle tests were conducted to evaluate the tribological properties and wettability of the coatings, respectively. The antibacterial activity of the coatings was estimated by SYTO9 nucleic acid staining with Staphylococcus aureus (Gram-positive bacteria). The cell cytotoxicity of the coatings was analyzed following the ISO 10995-5:2009 standard with human skin fibroblast cells. The Ti-V-O coatings, subjected to annealing at 700 °C, demonstrated higher hardness (Hv 1171) and a lower friction coefficient (0.6). The highest hardness (Hv 2711) and the lowest friction coefficient (0.52) were obtained for the Ti-V-O after laser surface texturing oxidation at 100 kHz. The oxide coating obtained from 100 kHz laser texturing oxidation exhibited the lotus effect because of its systematic textured microstructures, and displayed superhydrophobic surface properties. Compared with the unannealed TiV coating, both the samples with high-temperature annealing and laser surface texturing oxidation had excellent antibacterial properties to Staphylococcus aureus. However, the Ti-V-O thin films exhibited notable cell cytotoxicity. Although the cell viability on Ti-V-O coatings were not ideal, this study confirmed improvement in surface hardness, tribology, and antibacterial performance in Ti-V-O coatings, which may have potential for use in biomedical tools, devices, and equipment.

Tailoring the wetting characteristics of materials has gained much interest in applications related to surface cleaning in both industry and home. Zimbabwe black granite is a middle-to-fine-grained natural stone commonly used as countertops in kitchens and bathrooms. In this study, the laser texturing of Zimbabwe black granite surfaces is investigated with the aim to enhance its hydrophobic character, thus reducing the attachment of contaminants on the surface. Two laser sources (λ = 1064 and 532 nm) were used for this purpose. The treatment is based on the irradiation of the stone by a laser focused on the surface of the targeting sample. The influence of different laser processing parameters on the surface characteristics of granite (wettability, roughness, and chemistry) was statistically assessed. Most suitable laser processing parameters required to obtain the highest hydrophobicity degree were identified. It has been possible to identify the 532 nm laser wavelength as the most effective one to increase the hydrophobic degree of Zimbabwe black granite surface. The phenomenon governing wettability changes was found to be the surface roughness patterns, given the unaltered chemical surface composition after laser processing. [ABSTRACT FROM AUTHOR]

It is well known that elastomers usually possess poor dry sliding friction properties due to their highly adhesive character. In order to overcome this problematic behavior in industrial applications, interfacial materials such as oils, greases, coatings, or lacks are normally used in order to separate or to functionalize the contact surfaces of elastomers. Alternatively, the high adhesion tendency of elastomers may be explicitly reduced by modifying the elastomer composition itself or by enabling a reduction of its effective contact area through, for example, surface laser texturing. This second approach, i.e., the reduction of the adhesive character of elastomers through laser structuring, will be the main topic of the present study. For this purpose, different micro-sized grooved structures were produced on flat injection molds using an ultra-short pulsed laser. The micro-structured molds were then used to produce injection molded micro-ridged Liquid Silicone Rubber (LSR) sample pads. The investigations consisted firstly of determining the degree of replication of the mold micro-structures onto the surface of the LSR pads and secondly, to ascertain the degree of reduction of the friction force (or coefficient of friction) of these micro-ridged LSR pads in comparison to the benchmark (unstructured LSR pads) when tested under dry conditions against Aluminum alloy (Al-6082) or PA6.6-GF30 plates. For this second part of the investigation, the normal force (or contact pressure) dependency of the coefficient of friction was determined through stepwise load increasing friction tests. The results of these investigations have shown that the production of micro-ridged surfaces on LSR pads through laser structuring of the injection molds could be successfully achieved and that it enables a significant reduction of the friction force for low normal forces (or contact pressures), where the component of adhesion friction is playing an important and determining role in the overall friction behavior of the LSR elastomer. [ABSTRACT FROM AUTHOR]

The ablation resistance and adhesion strength of laser textured and as-sprayed functionally graded LaMgAl 11 O 19 /YSZ based thermal barrier coating (FG-TBC) was studied and compared with a duplex coating of LaMgAl 11 O 19 and YSZ (DC-TBC). The thermal barrier coatings were sprayed over Hastelloy C263 using atmospheric plasma spray process (APS). The laser texturing was performed using a picosecond pulsed laser. The width-to-depth ratio and groove spacing were varied to analyse and correlate the significance of groove parameters in providing strain tolerance under extreme thermal loading conditions. The ablation behaviour of the coatings was investigated using a scramjet test rig. The shear force induced through the ablation load spalled the as-sprayed DC-TBC. The thermal stress mismatch instigated through the difference in coefficient of thermal expansion (CTE) between discrete YSZ and LaMgAl 11 O 19 layers led to the failure of the as-sprayed DC-TBC. The as-sprayed FG-TBC exhibited an improved ablation resistance. The varying thermo-mechanical properties along the ceramic layer thickness in as-sprayed FG-TBC minimise the concentration of thermal stress across the coating and imparts better thermal stability. The improved mechanical interlocking of molten splats during re-solidification of five discrete layers of ceramic composites inhibits the concentration of stress around the weak links. Compared to the textured DC-TBCs, the textured FG-TBCs exhibited minimal level of distortion and better resistance to ablation. The textured surfaces restrict the propagation of crack across the top surface and also provide improved strain tolerance. The graded structure minimises the stress built up and improves the coating resistance compared to textured DC-TBCs. The adhesion strength of all test surfaces was analysed following the standard test procedure. The textured surfaces having higher surface roughness (in terms of surface area) exhibited improved adhesion strength. The groove parameters were observed to have significant influence in improving the ablation resistance and adhesion strength of the coatings. [ABSTRACT FROM AUTHOR]

The effects of laser texturing on the corrosion and wettability of AA2024-T3 using an IR Nd:Vanadate picosecond (ps) laser was studied. Three types of texture patterns were generated: dimples with 5% and 50% area density (percentage of surface area textured); cross groove patterns with an area density of 64%; and concentric ring patterns with an area density of 70%. For the higher area densities, the surface character changed from hydrophilic to hydrophobic. The evolution of the open circuit potential over time, potentiodynamic polarization curves and electrochemical impedance spectroscopy were then investigated and analysed. The results revealed that ultrashort ps laser surface texturing did not modify the corrosion behaviour of AA 2024-T3 in the test solution. [ABSTRACT FROM AUTHOR]

Surface finishing of parts plays a critical role in engineering applications. Although the efforts towards improving surface finish have been made over the past decades, the recent developments in science and technology accelerate the progresses made towards superior surface characteristics. Tailoring the physical and chemical characteristics of the surfaces enable to extend the surface engineering studies in many new fields including medical, biological, environmental engineering, and architecture. The current interest in self-cleaning of surfaces for energy applications, such as solar thermal and solar photovoltaic energy harvesting, makes the surface finish as one of the hot topics of the research. In the present study, laser texturing of silicon surface is presented in line with the self-cleaning characteristics. It is found that laser texturing gives rise to hydrophobicity characteristics at the surface because of: i) micro/nano size pillars, and ii) nitride phase formed at the surface. [ABSTRACT FROM AUTHOR]

Laser welding of dissimilar metals (steel and aluminium) was investigated with the aim to increase the maximum tensile shear load of the Fe-Al joints. The increase was achieved by texturing the surface of steel prior to the laser spot welding process which was performed in a lap-joint configuration with the steel positioned on top of the aluminium and with a texture faced down to the aluminium surface. This configuration enabled an increase of the bonding area of the joints, because the molten aluminium filled in the gaps of the texture, without the need of increasing the process energy which typically leads to the growth of the intermetallic compounds. Different textures (containing hexagonally arranged craters, parallel lines, grid and spiral patterns) were tested with different laser welding parameters. The Fe-Al joints obtained with the textured steel were found to have up to 25% higher maximum tensile-shear load than the joints obtained with the untextured steel. [ABSTRACT FROM AUTHOR]

For texturing of multicrystalline silicon wafers for solar cells, a HF-free texturing process was proposed by employing alkali cleaning (anisotropic etching) process after laser texturing. KOH/isopropyl alcohol (IPA) was more effective than KOH because the cleaning rate was rather slow but the shape of textured surface could be kept during the cleaning. After laser texturing with 5 min KOH/IPA cleaning at 80°C, the solar cell efficiency was increased from 4.6% to 12.6% because of the removing droplets of laser induced defects and the formation of microscopic textures by anisotropic etching. [ABSTRACT FROM PUBLISHER]

Laser gas assisted texturing of alumina surface is considered and the effects of graphene film on the properties of the textured surface are examined. Since laser texturing under the high pressure nitrogen gas jet environments results in formation of aluminum nitride compounds, free energy of the textured surface reduces considerably. The mismatch between the surface free energies of the graphene film and the laser textured surface makes it difficult to transfer the graphene film on the textured surface without rippling and edge defects. A graphene oxide film is formed at the textured surface prior to transferring of the graphene film. The characteristics of the laser textured and the graphene transferred surfaces are assessed using the analytical tools including electron and atomic force microscopes, Raman spectroscopy, X-ray diffraction, and UV visible absorbance spectroscopy. Surface hydrophobicity of the graphene transferred and laser textured surfaces is determined incorporating the water droplet contact angle measurement technique. Friction coefficient of the graphene transferred and laser textured surfaces are measured using the scratch tester. It is found that laser texturing results in hydrophobic characteristics because of the micro/nano size pillars formed at the surface and reduced surface energy due to aluminum nitride compounds. Transferring of the graphene film on to the laser textured surface reduces both the water droplet contact angle and the contact angle hysteresis. The presence of the graphene film reduces the friction coefficient and it does not alter notably the absorption characteristics of the laser textured surface. [ABSTRACT FROM AUTHOR]

Titanium alloys have become indispensable materials for lightweight and high-thrust-to-weight-ratio aeroengines owing to their low densities and high specific strengths. However, as the thrust-to-weight ratio increases, the temperature in an aeroengine increases to values considerably above the service temperature of the titanium alloy. Effective design and preparation of the interface structure are a potential approach to enhance the service life and dependability of thermal barrier coatings (TBCs). In this study, TBCs were prepared by spark plasma sintering (SPS) on Ti-6Al-4V, and a texture was engraved at the bond coating (BC)/top coating (TC) interface by a fibre laser. The laser texturing induced segmentation cracks. High-density segmentation cracks (dense vertical cracks (DVCs)) could be formed at densely spaced areas of the texturing. Based on the bimodal structure characteristic obtained by SPS, bimodal-structured DVC TBCs were realised, which provided the coating with higher strain tolerance and thermal insulation performance. After 138 cycles of thermal shock at 800 °C, the spallation area of a 2-mm square coating was only 34.55 % of that of unengraved TBCs. In addition, the laser-textured coating had a better thermal insulation performance. The thermal insulation temperature of a hexagonal 2-mm coating reached 215 °C. [Display omitted] • Induced segmentation cracks in thermal barrier coatings by laser texturing • Thermal barrier coatings with density segmentation cracks and bimodal structures were realised • Laser texturing at the interface gave the better thermal insulation performance [ABSTRACT FROM AUTHOR]

• Pool boiling tests were conducted on surfaces with uniform and mixed wettability. • Superbiphilic surfaces offer enhancements at atmospheric and subatmospheric pressures. • The enhancement with superbiphilicity is more significant for atmospheric pressure (up to 98%). Surface wettability is one of the key parameters in the manipulation of the boiling phenomenon. Although there are a number of studies on the effect of surface wettability on boiling heat transfer, there are few research efforts to explain the boiling phenomenon on superbiphilic surfaces at sub-atmospheric pressures. In this study, pool boiling experiments were conducted to investigate the boiling heat transfer performance of surfaces with uniform (superhydrophobic and superhydrophilic) and mixed (superbiphilic) wettability. This study presents the results obtained from four different surfaces for both atmospheric (103.7 kPa) and sub-atmospheric (28.3 kPa) pressures and aims to provide an understanding of the wettability effect using saturated deionized water as the working fluid in the heat flux range of 7 - 290 kW/m2. The experimental results show that the superbiphilic surface (superhydrophobic spots with a pitch size of 3 mm and diameter of 0.7 mm) offers improvements in boiling heat transfer at both atmospheric and sub-atmospheric pressures up to 98% and 54%, respectively. Due to bubble coalescence being more likely to occur at sub-atmospheric pressure, the enhancement effect of superbiphilicity on boiling heat transfer is more significant for atmospheric pressure. [ABSTRACT FROM AUTHOR]

A reliable strategy to enhance the bonding ability in hybrid titanium carbon laminates (HTCLs) is proposed, which is based on the pinning effect produced by bionic micro texture etched by laser on titanium and multi-walled carbon nanotubes (MWCNTs) introduced into adhesive layer. The characteristic of bionic micro texture is determined, and the strengthening mechanism of bonding interfaces is revealed. The HTCLs samples with various micro texture groove widths, laser scanning times and MWCNTs content are fabricated via an autoclave process. The micro texture morphologies, surface wettability, interlayer bonding properties under different conditions are studied. Results show that the recast layers formed on titanium during etching are beneficial to improve the interfacial bonding properties. Compared with no micro texture, the contact angle with micro texture can be reduced by 68.4%. Both micro texture and MWCNTs can reduce the defects at the interlayer interfaces and improve the interfacial adhesion. In this work, the maximum tensile shear strength (TSS) and interlaminar shear strength (ILSS) can be obtained with the micro texture groove width of 30 μm, the laser scanning of 30 times and the MWCNTs content of 0.4 wt%, which are 56.39% and 32.84% higher than that without any treatment, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

The paper reports an investigation into the functional response of textured surfaces with different designs that incorporated arrays of micro-dimples and grooves (40 μm diameter/width and 15 μm depth for both patterns) produced on tungsten carbide (WC) blocks by employing nanosecond (ns) and femtosecond (fs) lasers. In particular, the tribological performance of the textured WC blocks against stainless steel (SS316L) counterbody was evaluated in terms of friction and wear under dry condition compared to an untextured specimen. Friction tests were carried out on a reciprocating sliding tester while unidirectional ball-on-disc method was utilised to assess wear on the mating surfaces. The untextured surface exhibited a continuous rise in the friction coefficient from 0.15 to 0.5 from the start of the cycle to the end while the specimens textured with ns and fs lasers reached steady-state condition after 100 and 200 cycles with values between 0.35-0.45 and 0.3-0.4, respectively. Energy dispersive spectroscopy following wear tests showed a pronounced material transfer from the balls to the textured surfaces with stainless steel filling up some of the dimple and groove cavities; however, the reverse phenomenon was not apparent. Additionally, texturing with the fs laser exhibited formation of nano-ripples/structures in the produced dimples and grooves that can be further studied for creating nano-textured cutting tools or surfaces with super-hydrophobic/anti-ice properties. [ABSTRACT FROM AUTHOR]

A facile and highly-efficient laser scanning process coupled with a simple silanization modification was used to prepare textured titanium (Ti) surfaces with stable superhydrophilicity and superhydrophobicity. Femtosecond pulsed laser scanning along two mutually perpendicular directions led to the formation of binary structures featuring micrometer-scale spikes covered with nanometer-scale ripples. The period of the spikes significantly increased and the period of the ripples irregularly changed in the narrow range of 550–600 nm with the increase of laser fluence. The obtained laser-textured Ti surfaces were hydrophilic or even superhydrophilic, and the superhydrophilic laser-textured Ti surface using a laser fluence of 1.5 J/cm 2 was observed to retain its wetting property after 30 days of storage in ambient atmosphere. After silanization, all the laser-textured Ti surfaces exhibited high hydrophobicity or superhydrophobicity, and the superhydrophobic laser-textured Ti surfaces using laser fluences of 1.5 and 1.8 J/cm 2 remained stable when stored in air for over 30 days. The results imply the potential applications of these surfaces in a variety of fields. [ABSTRACT FROM AUTHOR]