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Nucleate pool boiling experiments were performed on plain and five laser-textured stainless-steel foils using saturated pure water, 100% ethanol, 0.4% and 4.2% mole fraction ethanol – water mixtures. All laser-textured samples contained untreated, smooth 0.5 mm wide regions and intermediate textured surfaces, that differ in the width of the laser patterned regions (from 0.5 mm to 2.5 mm). For smooth surfaces, we measured significant decreases in average heat transfer coefficients (HTC) and increases in bubble activation temperatures in comparison with the laser-textured surfaces for all the tested working fluids. Significant enhancement in HTC (280%) on a textured heating surface with 2.5-mm-wide laser pattern was recorded using pure water. For pure ethanol, the highest enhancement of 268% was achieved on a heating surface with 1.5-mm-wide laser pattern. The highest enhancement of HTC for the tested binary mixtures was obtained using 2.0-mm wide-laser-textured regions (HTC improved by 235% and 279% for the 0.4% and 4.2% mixtures, respectively). Our results indicate that laser texturing can significantly improve boiling performance when the intervals of the laser-textured patterns are close to the capillary lengths of the tested fluids. [ABSTRACT FROM AUTHOR]

A model of magnetohydrodynamic partial slip laser texture bearing (slider and journal) is developed. The influence of laser bump texture and slip laser texture partial configuration on the magnetohydrodynamic performance analysis of bearing is presented. An electrically conducting fluid is confined to bearing surfaces under uniform magnetic field perpendicular to slider bearing and inclined to the line of maximum film thickness to journal bearing. A one-dimensional analysis based on the narrow groove theory is considered to evaluate the nondimensional pressure distribution in bearing. Results of the nondimensional load capacity and coefficient of friction of magnetohydrodynamic partial laser bump texture and partial slip laser texture bearing configurations are analyzed. Partial slip configuration under MHD lubrication without laser bump texture brings in the performance improvement. [ABSTRACT FROM AUTHOR]

Poor wear properties severely limit the field of application and service life of titanium alloys. Three kinds of textures (dimple, groove and mesh) were prepared by laser texturing technique and compounded with micro-arc oxidation treatment to improve the tribological properties of titanium alloys in this study. The coatings' morphology, structure, and composition were characterized, and their antiwear properties were analyzed. The results show that the proportion of rutile phase in the coating increases with increasing textured area rate and that the textured edge coating has higher Si and P content, with increased thickness and densities. In terms of friction properties, the dimpled texture shows the best friction properties when textured alone, with a 28.6 % decrease in the average coefficient of friction compared to the substrate; in contrast, the meshed texture shows the best friction properties after the micro-arc oxidation treatment, with a 76.2 % decrease in the average coefficient of friction compared to the substrate. Studies have shown that laser texturing can reduce wear by retaining abrasive debris. However, laser texturing alone does not provide a significant increase in hardness at the edge location, which is more susceptible to damage during wear, leading to more severe wear. The "tip effect" encourages the growth of a micro-arc oxide layer, and the resulting hardness of the layer helps protect the texture structure from damage. The synergistic effect of the texture and the rough, hard structural features of the coating itself enhances the wear resistance of the composite coating. • Laser texturing combined with micro-arc oxidation enhances titanium alloy's wear resistance. • Impact of texture shapes on growth and composition of microarc oxide coatings was discussed. • The analysis studied wear reduction mechanisms of coatings and the impact of various texture shapes on wear [ABSTRACT FROM AUTHOR]

The decline in freshwater availability has spurred research into employing solar desalination technology. Recent research has concentrated on investigating the use of surface modification to improve the productivity of solar still for desalination. This paper presents the use of femtosecond laser texturing to induce a porous surface on the polymethyl methacrylate (PMMA) cover of a solar still for producing filmwise condensation. Vertical lines 2.5 mm wide were fabricated on the PMMA surface using ultrafast laser texturing, and experiments were conducted using the modified cover on a solar still at a constant basin water temperature. Results show that the static water contact angle measured on the cleaned laser textured surface is hydrophobic. However, the formation of the porous structure leads to a change in wetting state from Cassie-Baxter to Wenzel upon exposure to water vapour. This change in wetting state enables the formation of filmwise condensation under the continuous presence of water vapours. The solar still productivity improves by 15.4 % and 23.1 % using both cleaned and uncleaned laser textured surfaces respectively. The modified surface is stable upon repeated exposure to water vapour, thus proving to be an excellent surface modification method for enhancing PMMA covered solar still performance. • Filmwise condensation forms on the laser textured lines due to the porous surface. • Cassie-Wenzel droplet state transition is seen on the porous hydrophobic surface. • Laser texturing improves heat dissipation of the PMMA cover. • Freshwater output decrease with an increase in laser textured surface area ratio. • Modified PMMA morphology and chemistry remain stable after repeated experiments. [ABSTRACT FROM AUTHOR]

As the most common protective layer in car body protection, the paint layer is an effective barrier against corrosion of the material matrix. The adhesion between the paint layer and the substrate is an important factor in ensuring the long-term and effective protection of the paint layer. On the 5083 aluminium alloy substrate, a series of laser micro-texture with varying depths are produced by laser texturing, with the aspect ratio ranging from 0.12 to 1.76. The adhesion test of standard GB/T 5210–2006 was used to investigate the effect of different texturing depths on the adhesion strength of the paint layer. The cross-sectional microstructure and fracture morphology of the paint layer were analysed and characterized to study the deposition and fracture mechanism of the paint layer. The results show that the presence of laser micro-texture significantly enhances the adhesion of the paint layer, and the influence of laser micro-texture of different depths and dimensions on the adhesion of the paint layer is different. And found that the optimal depth size affecting the size of adhesion is around 0.67. By analyzing the cross-sectional microstructure and fracture morphology of the paint layer, it is found that the change in paint adhesion is the result of the change of developed interfacial area ratio (Sdr), the bonding condition of the paint layer and the substrate surface, and the bubble defect. At the same time, the process of the paint layer flowing on the substrate surface, filling the micro-texture, and forming bubbles was analysed. • Laser texturing produces a range of microfibres in depth-to-width ratio. • Significant improvement in surface roughness and specific surface area with laser texturing. • The gas recoil pressure created by gasifying the material is the main factor in forming laser microfabrics. • The depth-to-width of the micro-texture is most conducive to paint adhesion when the aspect ratio is around 0.67. [ABSTRACT FROM AUTHOR]

Surface laser texturing is used to ensure mechanical anchoring and strengthen adhesion between the interfaces of bond coatless thermal barrier coating system. To anticipate a possible loss of mechanical properties and to adapt to the perpetual evolutions of chemical compositions of the system, we analyzed the microstructural evolutions of different Ni-based single crystal superalloys, induced during infrared nanosecond laser ablation. Localized asperities composed of a melted, re-solidified matter, with a different microstructure from that of the bulk material, were generated. Regarding asperity morphologies, recrystallization within the latter could be avoided. Then, to compare different Ni-base single crystal superalloys, the thermal-affected volumes were characterized for two patterns textured under different energetic conditions. It seems that all the studied single crystal superalloys behaved quite similarly during nanosecond laser ablation. Finally, according to these results, ablation kinetics between the γ and γ′ phases of Ni-based superalloys could not be homogeneous.

Making decisions and deducing control actions in manufacturing environments requires considering many uncertainties. The ability of fuzzy logic to incorporate imperfect information into a decision model has made it suitable for the optimization of both productivity and final quality. In laser surface texturing for wettability control, in fact, these aspects are governed by a complex interaction of many process parameters, ranging from those connected with the laser source to those concerning the properties of the processed material. The proposed fuzzy-based decision approach overcomes this difficulty by taking into account both the random error, associated with the process variability, and the systematic error, due to the modelling assumptions, and propagating such sources of uncertainties at the input level to the output one. In this work, the laser surface texturing was carried out with a nanosecond-pulsed laser on the surfaces of AISI 304 samples, changing the laser scanning speed, the hatch distance, the number of repetitions, and the scanning pattern. A significant change of the contact angle in the range 24–121° is observed due to the produced textures. The fuzzy maps highlight the inherent uncertainty due to both the laser texturing process and the developed model.

In this work, direct irradiation by a Ti:Sapphire (100 fs) femtosecond laser beam at third harmonic (266 nm), with a moderate repetition rate (50 and 1000 Hz), was used to create regular periodic nanostructures upon polystyrene (PS) thin films. Typical Low Spatial Frequency LIPSSs (LSFLs) were obtained for 50 Hz, as well as for 1 kHz, in cases of one spot zone, and also using a line scanning irradiation. Laser beam fluence, repetition rate, number of pulses (or irradiation time), and scan velocity were optimized to lead to the formation of various periodic nanostructures. It was found that the surface morphology of PS strongly depends on the accumulation of a high number of pulses (103 to 107 pulses) at low energy (1 to 20 µJ/pulse). Additionally, heating the substrate from room temperature up to 97 °C during the laser irradiation modified the ripples’ morphology, particularly their amplitude enhancement from 12 nm (RT) to 20 nm. Scanning electron microscopy and atomic force microscopy were used to image the morphological features of the surface structures. Laser-beam scanning at a chosen speed allowed for the generation of well-resolved ripples on the polymer film and homogeneity over a large area.

This paper analyses the possibility of obtaining surface-infused nano gold particles with the polyether ether ketone (PEEK) using picosecond laser treatment. To fuse particles into polymer, the raw surface of PEEK was sputtered with 99.99% Au and micromachined by an A-355 laser device for gold particle size reduction. Biomimetic pattern and parameters optimization were key properties of the design for biomedical application. The structures were investigated by employing surface topography in the presence of micron and sub-micron features. The energy of the laser beam stating the presence of polymer bond thermalisation with remelting due to high temperature was also taken into the account. The process was suited to avoid intensive surface modification that could compromise the mechanical properties of fragile cardiovascular devices. The initial material analysis was conducted by power–depth dependence using confocal microscopy. The evaluation of gold particle size reduction was performed with scanning electron microscopy (SEM), secondary electron (SE) and quadrant backscatter electron detector (QBSD) and energy dispersive spectroscopy (EDS) analysis. The visibility of the constituted coating was checked by a commercial grade X-ray that is commonly used in hospitals. Attempts to reduce deposited gold coating to the size of Au nanoparticles (Au NPs) and to fuse them into the groove using a laser beam have been successfully completed. The relationship between the laser power and the characteristics of the particles remaining in the laser irradiation area has been established. A significant increase in quantity was achieved using laser power with a minimum power of 15 mW. The obtained results allowed for the continuation of the pilot study for augmented research and material properties analysis.

Owing to the relevance of the turning operation to the metal working industry, intensive research is constantly undertaken in order to improve the quality of manufactured products, optimise production time, and reduce costs. Among the investigated topics, texturing of the cutting tool rake face has received increasing attention since it can affect tool life, process forces, and cutting temperature. The contribution of the present work resides in depicting the procedure for laser texturing the cutting edge chamfer of uncoated tungsten carbide inserts aiming at weakening the stability of the seizure region. Moreover, the performance of textured and non-textured tools was assessed when turning grey cast iron. Two parallel columns of dimples with an average diameter of 40 μm and variable distance between rows of dimples (60, 100, and 200 μm) were produced and the turning experiments were carried out dry and with the application of minimal quantity lubrication (MQL). The findings indicated that the lowest values for the turning force components were obtained when cutting with textured tools possessing dimples 100 μm apart and using MQL. Texturing did not affect tool life in dry turning; however, when cutting with MQL, the longest tool lives were obtained using the tools textured with dimples 60 and 100 μm apart. Finally, machined surface roughness was not affected by tool texturing and decreased slightly with the application of MQL. [ABSTRACT FROM AUTHOR]

Laser-based surface texturing provides highly controlled interference fit between two parts. In this work, artificial intelligence-based models were used to predict the surface properties of laser processed stainless steel 316 samples. Artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) were used to predict the characteristics of laser surface texturing. The models based on feedforward neural network (FFNN) were developed to examine the effect of the laser process parameters for surface texturing on 316L cylindrical pins. The accuracy of the models was measured by calculating the root mean square error and mean absolute error. The reliability of the ANFIS and FFNN models for the output prediction of the laser surface texturing (LST) system were investigated by using the data measured from experiments based on a 3^3 factorial design, with main processing parameters set as laser power, pulse repetition frequency, and percentage of laser spot overlap. The relative assessment of the models was performed by comparing percentage error prediction. Finally, the impact of input data was examined using predicted response surface plots. Results showed that ANFIS prediction was 48% more accurate compared with that provided by the FFNN model. [ABSTRACT FROM AUTHOR]

Stability of functionalized surfaces is an often-neglected topic in phase-change heat transfer research. Here, we examine the chemical and morphological changes of textured surfaces on the molecular and atomic level after the critical heat flux incipience during saturated pool-boiling of water. SEM imaging, EDS, AES and XPS analyses are used to examine the surface changes. Copper samples were laser textured via ablation using a nanosecond fiber laser under air or argon atmosphere. Multiscale microcavities, which serve as preferential nucleation sites, were produced on the samples, which exhibited significantly enhanced heat transfer performance in pool-boiling tests. Repeated formation of a vapor film and accompanying temperatures of up to 320 °C during the tests resulted in changes of the surface chemistry and nanomorphology. It was determined that Cu (II) oxide and hydroxide transform into Cu (I) oxide and Cu metal as a result of repeated low-temperature annealing of the surface when a vapor film is formed during the transition towards film boiling. This additionally causes a wettability transition of the functionalized surfaces from hydrophilic towards hydrophobic. Both effects importantly influence the solid-liquid-vapor interface during phase-change heat transfer. Overall, surfaces functionalized via laser texturing exhibited significantly enhanced stability and boiling heat transfer performance. Unlabelled Image • Copper surfaces are modified using nanosecond laser-texturing • Pool boiling heat transfer on textured surfaces is significantly enhanced • A shift in boiling curves after the first CHF incipience is observed and investigated • Surface chemical composition is analyzed and correlated with boiling behavior • Conversion of CuO and Cu(OH) 2 into Cu 2 O and Cu as a result of CHF onset is detected [ABSTRACT FROM AUTHOR]

Contact line movement over laser-textured metal alloy surfaces depends on the texture, droplet state, inversion of wettability, and liquid flow rate. Ordered and anisotropic textures were created by a nanosecond pulse laser on aluminum-magnesium alloy surfaces. Microrelief was studied on a profilometer and scanning electron microscope. Changes in wetting properties and the characteristics of spreading were obtained. To implement wetting cycles, liquid was dispensed with a syringe pump using the bottom-up method. The results provide new, in-depth knowledge to understand the mechanisms of the contact line movement on laser-textured metal surfaces. We have shown that by creating a texture with given parameters (ordered or anisotropic), it is possible to predict a change in wettability from superhydrophilic to hydrophobic, as well as a droplet state. In this paper, we have demonstrated that the contact angle hysteresis determines not only the deviation of the contact angle from equilibrium, but also the adhesion force between the droplet and the surface, a droplet state (Wenzel or Cassie-Baxter), and the wetting anisotropy of local areas on laser-textured alloy. We have recorded two states of the droplet on formed textures: the Wenzel with air cushions on anisotropic and the Wenzel with complete filling of cavities with water on ordered textures. [ABSTRACT FROM AUTHOR]

In this study, double-layer coatings of graphene oxide (GO)-poly(vinyl pyrrolidone) (PVP) (PGO) were deposited on the micro-textured Ti6Al4V substrates by electrophoretic deposition. Results revealed that the combination of micro-dimples and bi-layer PGO coatings significantly reduced the friction coefficient of textured Ti6Al4V from 0.5 to <0.03. PGO layer provided both relatively smooth surface of PVP for suitable adhesion and a rigid layer of GO for load bearing. Moreover, the textured micro-dimples acted as sinks to preserve the PVP and GO fragments and wear debris leading to sustain low friction coefficient for a long period of operation. In addition, our results demonstrated that the bi-layer PGO coating on the micro-textured Ti6Al4V substrate resulted in significant improvement of MG63 cell attachment and proliferation. In summary, PGO coated textured Ti6Al4V with simultaneously improved wear resistance and biological function have the potential for orthopedic implants. • Bi-layer coating of GO-PVP(PGO) was deposited via on micro-textured Ti6Al4V. • The combination of micro-dimples and PGO coating significantly reduced wear rate of Ti6Al4V. • Textured micro-dimples acted as sinks to preserve the PVP and GO components and wear debris. • Bi-layer PGO coating on the micro-textured Ti6Al4V improved MG63 cell proliferation. [ABSTRACT FROM AUTHOR]

The aim of this work was to texturize surfaces of steel engine components to reduce the coefficient of dynamic friction and wear between two surfaces. The elements of the texture had the shape of a spherical half-shell and were produced by the overlap of femtosecond laser pulses with donut shape. The incubation effect was estimated using the D-scan method to relate the ablation threshold to the number of overlapping pulses. Thus, the control of the focal position of the laser beam and the number of overlapped pulses, taking into account the effects of incubation, made it possible to obtain this type of dimple with controlled shape and size. A distribution of dimples with density of 11% caused an 18% reduction in the coefficient of friction in a tribological pair DIN 16MnCr5 and SAE 52100 steel sphere. [ABSTRACT FROM AUTHOR]

Drop splashing is a very common phenomenon when liquid drops impact on solid surfaces. In this study, picosecond laser fabricated hybrid superhydrophobic/-philic (SH/SHL) surfaces with designed patterns are successfully applied to control drop splashing on solid surfaces. Using high-speed imaging, the water drop impact behaviors on differently patterned hybrid SH/SHL surfaces were investigated. The experimental results show that the water drop splashing could be restrained greatly on patterned hybrid SH/SHL surfaces, compared with SH or SHL surfaces. On a hybrid SH/SHL surface with a 2 mm diameter circular SH pattern, the drop splashing for a Weber number up to 600 (the corresponding impact velocity is 4.2 m/s) can be totally suppressed. Moreover, we found that the oriented distribution of splashing can be regulated by the shape and size of SH patterns. These results suggest that patterned hybrid SH/SHL surfaces could be a practical approach to regulate or control drop splashing. • Patterned superhydrophobic/-philic surfaces are first proposed to control drop splashing on solid surfaces. • Picosecond laser is a facile and efficient tool to regulate the size and shape of superhydrophobic patterns on superhydrophilic surfaces. • Superhydrophobic surfaces are beneficial for suppressing the splashing generated at the early stage of drop impact. • Oriented distribution of splashing can be regulated by the shape and size of superhydrophobic patterns. [ABSTRACT FROM AUTHOR]

This study provides a novel way to research the drag friction of tools and shows significant potential in reducing tool wear and prolonging tool life. First, we fabricated amphiphobic micro-/nano-structures on the cemented carbide tool surface by a pulsed fiber laser. Various kinds of texture morphology could be obtained by controlling the laser parameters, including laser energy density (D), scanning speed (V), and the scanning number of the laser beam (N). Then, the contact angles (CA) were tested for the untextured, micro-textured, and micro-/nano-textured tools. The consequences indicated that the micro-/nano-textured tool showed the lowest wettability. The water contact angle (WCA) and oil contact angle (OCA) of it could, respectively, be achieved to 147 ± 3° and 135 ± 3°. Finally, cutting performance and anti-friction mechanism of textured cemented carbide tools with various wettability levels were experimentally investigated by cutting the 15-5PH stainless steel with solution treatment. The results indicated that in the state of minimal quantity of lubrication (MQL), the cutting force, the average friction coefficient on the rake face, and the cutting temperature could be reduced by the micro-/nano-texture with low wettability on the tool surface. Simultaneously, we analyzed the mechanism of formation of micro-/nano-bulge structures on the tool surface. [ABSTRACT FROM AUTHOR]

Two distinct surface topographies consisting of micro- and nano-surface were developed using laser texturing (LT) and anodization process respectively and their effect on the surface-related properties of Ti-6Al-4V fabricated using Laser Engineered Net Shaping (LENS) were determined. The topographies developed using laser texturing (25, 50 and 75% overlap) were examined using 3D profilometer, whereas, Field Emission Scanning Electron Microscopy (FE-SEM) was used to analyze Titania NanoTubes (TNT) formed using anodization. Though all the surface modified specimens exhibited hydrophilic behavior, least contact angle values were observed for the specimen surface modified with TNT. 25LT and 50LT specimens offered about 8 fold higher corrosion resistance than TNT specimens. All the surface modified samples exhibited non-toxicity to blood cells as well as to the mesenchymal stem cells (hMSCs) with a higher rate of proliferation and differentiation hMSCs observed on 75LT specimens and TNT specimen. There is an urgent need to increase the current life-span of commercially used implant. Ti-6Al-4V implant material with enhanced mechanical stability than its wrought counterpart has been developed using LENS technique. Hence, we have attempted to modify its surface to develop micro- and nano-surface topographical features using laser texturing and anodization. Our results lay the foundation to modify the implant surface using a simple and cost effective technique which would not only accelerate bone healing but also improve the long-term stability of the implant by providing resistance to corrosion due to the aggressive ions present in the biological microenvironment. Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract The paper reports an investigation on the mechanical durability of textured thermoplastic surfaces together with their respective wetting properties. A range of laser-induced topographies with different aspect ratios from micro to nanoscale were fabricated on tool steel inserts using an ultrashort pulsed near infrared laser. Then, through micro-injection moulding the topographies were replicated onto polypropylene surfaces and their durability was studied systematically. In particular, the evolution of topographies on textured thermoplastic surfaces together with their wetting properties were investigated after undergoing a controlled mechanical abrasion, i.e. reciprocating dry and wet cleaning cycles. The obtained empirical data was used both to study the effects of cleaning cycles and also to identify cleaning procedures with a minimal impact on textured thermoplastic surfaces and their respective wetting properties. In addition, the use of 3D areal parameters that are standardised and could be obtained readily with any state-of-the-art surface characterisation system are discussed for monitoring the surfaces' functional response. Graphical abstract Unlabelled Image Highlights • The mechanical durability of textured surfaces is studied. • Laser-induced topographies were replicated onto polypropylene surfaces. • The surface energy and the Wenzel/Cassie-Baxter state of the textured surfaces were quantified. • The hydrophobicity decreased with the progressive abrasion of the topographies. • Standardised 3D areal parameters were correlated with surface wettability. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Wettability of AISI 304 was tailored by ns laser texturing in different atmospheres. • Wetting modifications follow changes in surface chemistry among the atmospheres. • Laser processing parameters modulate the resulting wettability in each atmosphere. • Both superhydrophilic (θ = 0°) and superhydrophobic (θ = 152°) surfaces were obtained. • No costly vacuum chambers or additional coatings required. Abstract Wettability plays a major role in a variety of surface related phenomena, as corrosion, heat transfer or tissue adhesion on implants. Consequently, great research effort is being devoted to control the wetting degree of functional surfaces. Pulsed laser texturing at micro/nanometric level has been widely used for that purpose as a precision/time efficient technique. This work studies the role of the processing atmosphere in controlling the wettability of commercial AISI 304 by laser texturing. A pulsed laser source (λ = 532 nm) working at the nanosecond regime was employed and five different atmospheres were tested (i.e. O 2 , Air, CO 2 , N 2 , Ar). The results show clear differences in the wetting behaviour depending solely on the processing environment, ranging from hydrophilicity (31°) to hydrophobicity (125°). Those differences in wettability were found to be a consequence of changes in surface chemistry between samples processed under the various gases. The laser processing parameters showed a capability to tune the final wetting behaviour by controlling the topography and modulating the chemical composition given by the processing environment. It is demonstrated how the effects of the atmosphere can be exploited to tailor the wettability of the untreated surfaces (θ = 88°) up to the desired value, ranging from superhydrophilicity (θ = 0°) to superhydrophobicity (θ = 152°). [ABSTRACT FROM AUTHOR]

Surface texturing of metals and alloys has recently been identified as an environmentally friendly alternative to the use of high-performance lubricants with complex formulations. Adding micro-scale textures to one or both sliding surfaces of mechanical components can reduce friction and wear compared to conventional/untextured surfaces. This study investigates the effect of laser textured surfaces on the tribological behavior of titanium Ti6Al4V. Multiple texture types were created by varying the energy density of pulse and scanning speed of the laser. These variations modify the outer layers of the alloy, rising the generation of specific topographies and changing the initial properties by means of microstructural modifications and oxidation processes. The performance of these surfaces was evaluated using a ceramic ball in a ball-on-flat reciprocating tribometer under lubricated conditions. Wettability of the tribological system was examined by measuring the contact angle of the oil used on textured and conventional surfaces. Tribological performance of textured surfaces was found to strongly depend on the laser patterning parameters. Replacing conventional surfaces with textured surfaces reduced friction up to 62% and wear up to two orders of magnitude. Wear mechanisms are discussed from optical microscopy and SEM/EDS observation of wear tracks on titanium disks and ceramic balls. [ABSTRACT FROM AUTHOR]

Abstract Laser gas assisted texturing of tungsten surface is carried out towards achieving increased solar absorption at the surface. Morphological and metallurgical changes at the textured surface are examined using the analytical tools. Hydrophobic characteristics of the surface are assessed incorporating the water droplet contact angle measurement technique. The influence of environmental dust on the laser textured surface is investigated mimicking the humid air ambient. The adhesion of the dry mud on the textured surface is determined through measurement of tangential forces required to remove the dry mud from the surface. It is found that laser gas assisted processing results in surface texture composing of micro/nano pillars and formation of WO 3 compounds in the treated layer. Hydrophobicity of the surface improves significantly after the laser texturing; in which case, the water droplet contact angle increases from 64° to 94°. The dry mud and dried liquid solution residues influence the UV visible absorption of the laser textured surface. In this case, absorption reduces almost 20% because of scattering of incident UV visible radiation by the residues at the textured surface. Highlights • Laser gas assisted texturing results in WO 2 and WO 3 compounds at surface. • Laser treatment improves surface hardness and hydrophobicity. • Absorptivity of laser surface improves significantly because of WO 3 compound. • Dust adhesion surface lowers absorptivity of laser treated surface. • Force required removing dry mud from laser textured surface is significantly higher than friction force. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Two types of textures are obtained by ns laser radiation of aluminum surface. • A procedure for the unification of texture formed by ns laser radiation is proposed. • The connection between wettability, texture and elemental composition are defined. • The elemental composition of the periodic textures is uneven over the surface. Abstract Laser texturing of metals is a promising way to create surfaces with unique functional properties. The widespread implementation of this method into industry is hampered by the lack of theoretical basis to predict the change in their functional properties. We propose a procedure for the unification of textures formed on aluminum surfaces after nanosecond laser radiation texturing. Using amplitude and hybrid roughness parameters, as well as power spectrum density function, we conditionally divided formed textures into two groups. The first is anisotropic multimodal from nano- to micro-scale texture in three coordinate directions. The second group combines periodic texture with separate elements. The static contact angle grew more slowly in time on the first group surfaces after laser texturing but reached higher values. We found the relationship between the contact angle evolution, the location of the texture elements relative to each other and the elemental composition. The elemental composition of the second group of the texture is uneven over the surface, depends on the location of the texture elements formed after laser radiation. The results can be used for laser texturing of aluminum surfaces for predictive evaluation of wetting properties, changing them in time based on analysis of the created texture. [ABSTRACT FROM AUTHOR]

Abstract Tool surface modification strategies are expected to achieve energy efficient dry cutting pertaining tribological advantages of textured surfaces. Current work focuses on both experimental and finite element based approaches to understand the effect of textured and coated textured tools on machining performance of Ti6Al4V alloy. Novel chevron textured tools were fabricated using nanosecond fiber laser and further coated with PVD-TiAlN coating. 2D FE simulation studies for turning with uncoated textured and TiAlN coated-textured tools were performed and compared with plain and coated-plain tools. The effectiveness of the textured tools is evaluated in terms of cutting forces, average friction coefficient, tool-chip contact length, chip disentangling behavior, and shear stresses between coating-substrate adhesions. Results confirm that the coated textured tool is helpful in machining performance improvement of Ti6Al4V alloys even at comparatively higher cutting speeds and feed. The concept of interface multipoint micro-cutting (IMP-μC) at varying machining speeds was observed from FE simulations and verified from experimental results. Highlights • Plain and chevron textured tools were used with uncoated and TiAlN coatings for turning of Ti6Al4V. • Cutting tests were conducted for forces, apparent friction, chip contact length, curling and disentangling behavior. • Experimental results are validated for FE simulations and compared for the analysis. • Texture induced derivative cutting phenomenon is explained with FE simulations and experimentally validated. • Reduction in maximum shear stresses at flank for textured tools reduced delamination of coatings. [ABSTRACT FROM AUTHOR]

In this work, a mathematical relationship has been formulated between laser texturing process variables and the Ultimate Tensile Strength (UTS) of the AZ31B Mg alloy joints made by Cold Metal Transfer welding (CMTW) process. The nominal depth (D), diameter (Ø) and separation distance (SD) were the input parameters and three-factor and two-level central composite design (CCD) was applied to build up the experimental design matrix. By fixing the already optimized parameters of CMTW viz: current intensity 60A, Welding Speed 6 mm/sec, Gas flow rate 14 L/min and Nozzle to Plate Distance 6 mm and with the experimental matrix using laser texturing process variables, twenty joints were produced using CMTW process. The UTS was measured by standard ASTM procedure. The ANOVA was performed to find out the most significant main and interaction parameters and empirical relationship was determined. The laser texturing process (LST) variables were optimized by making response graphs and contour plots using Minitab software. The formulated mathematical relationship would be useful to forecast the UTS of CMT welded AZ31B joints for stipulated confidence limit. The contour plots will be helpful to acquire the optimal conditions of LST process variables. [ABSTRACT FROM AUTHOR]

• A method based on image processing is proposed to identify the regular deterministic laser texture pattern. • A detailed image processing steps followed to identify the texture pattern. • A proposed radial length function is used to identify the pattern using correlation measures. • The ISO concept of circularity definition extended to triangle, elliptical, square patterns. • The error of the measurement is calculated using the proposed method. Texturing of surfaces is often done to improve the surface properties. The purpose of this study is to develop a methodology for two dimensional inspection of the quality of textured surfaces automatically using machine vision techniques. The quality is measured in an absolute sense, using the value of offset between ideal shapes that inscribe and circumscribe the boundary of a machined feature. This gives an idea about machining accuracy rather than similarity between the machined texture shape and intended ideal shape which most of the existing methods try to measure. The techniques developed are tested on textures created on polished titanium surface using laser micro machining technique. In this study the textured surfaces made up of four different shapes namely circle, ellipse, triangle and square are considered. The automatic classification of texture shapes into the mentioned categories is achieved by finding their correlation with ideal shapes. For the purpose of measuring the machining accuracy, this paper extends the ISO definition of circularity error to ellipse, triangle and square shapes and proposes a method to fit least square triangle and square shapes to a given two dimensional point clouds. The error and the average dimension of the features are calculated from circumscribing, inscribing and least square fit shapes. The results generated by the proposed algorithms are found to be in good agreement with the known dimension values set during machining of the samples and manual measurements done using a stereo-microscope images. This indicate the suitability of this procedure for characterization of textured surfaces for different applications. [ABSTRACT FROM AUTHOR]

This paper reports on study of laser texturing assisted abrasive flow finishing (LT-AFF) process of the hobbed spur gear (HSG) to further improve their microgeometry, surface finish, micohardness, microstructure, wear resistance, and material removal rate (MRR) as compared to AFF process. Preliminary experiments were conducted to identify optimum values of power and focal length of the continuous fiber laser of 1064-nm wavelength, and number of passes for laser texturing of the HSG made of 20MnCr5 alloy steel. Identified optimum values were used to produce homothetic texture on flank surfaces of HSG in a direction perpendicular to the lay profile generated by hobbing. Influence of laser texturing was studied by comparing deviations in microgeometry, average and maximum surface roughness values, microhardness, wear resistance, and MRR of HSG directly finished by AFF and laser-textured hobbed spur gears (LTHSG) finished by AFF. Previously optimized value of viscosity of AFF medium was used during finishing of HSG and LTHSG. Deviations in total profile, total lead and total pitch, and radial runout were used to indicate deviation in microgeometry of the spur gears. Results reveal that AFF of LTHSG reduced surface roughness and errors in microgeometry and improved microhardness, microstructure, wear resistance, and MRR than direct of AFF of HSG. Improved microgeometry and surface quality of spur gears will lead to their increased operating performance and service life thus reducing their running noise and vibrations and preventing their premature and failures. This research proves that productivity of AFF process can be improved significantly by laser texturing for finishing the spur gears. [ABSTRACT FROM AUTHOR]

Substrate preparation plays an important role in the performance of thermal spray coating, especially on softer materials like magnesium and aluminium alloys. Conventional substrate preparation methods such as grit blasting may not be the most suitable choice due to grit embedding, lower coating adhesion strength and environmental concerns. Laser texturing can be an attractive alternative to the grit blasting method for such materials. AZ91D substrate was prepared for thermal spray coating using grit blasting and laser texturing techniques. WC-12Co powder was thermally sprayed on AZ91D magnesium alloy using the high-velocity oxygen fuel technique. The adhesion strength of the coating, thus produced, was determined using the ASTM 633C adhesion strength test. Scanning electron microscopy was used to investigate substrate morphology and to qualitatively analyse substrate and coating interface. X-ray diffraction was used to identify phase compositions. The coating was characterised for roughness, porosity, micro-hardness and fracture toughness. Laser texturing as a substrate preparation technique has been able to produce well-adhered coatings, with adhesion strength of 45.6 MPa, and comparable coating characteristics with those of the grit blasting technique. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Patterned GFRP superhydrophobic surface was fabricated by laser texturing. • Achieve over 88% of the underwater acoustic absorption from 50 kHz to 250 kHz. • High acoustic absorption ascribes to the multiple interface scattering effect. Abstract Underwater acoustic absorption metasurfaces (UAAMs), featured with artificial periodic unit cells as acoustic micro-absorbers, are crucial for the enhancement of the underwater stealth, energy transition, sonar detection, etc. How to implement the acoustic metasurfaces for practical engineering applications requires the support of efficient manufacturing techniques. Here we present a simple way of laser texturing for fabrication of the patterned superhydrophobic surface on glass fiber reinforced plastic (GFRP). Unlike the traditional acoustic absorbing material whose thickness should match the corresponding wavelength, the laser textured superhydrophobic micro-grooves have thickness less than the absorption sound wavelength by 2–3 orders of magnitude but promisingly demonstrate over 88% of the underwater incident acoustic power absorption from 50 kHz to 250 kHz. The physical mechanism of the UAAM ascribes to the multiple interface scattering effect induced by the air layer between water and superhydrophobic micro-nano structures. [ABSTRACT FROM AUTHOR]

Highlights • Study on the laser-texturization of AZO films with 355 nm nanosecond laser pulses. • High haze factor of laser-textured samples in the 400–900 nm wavelength range. • Morphologies generated by the laser process plays a key role in light scattering. • AZO samples with high haze factor lead to an improvement in the cells Jsc current. Abstract With the objective of increasing light scattering and obtaining a higher light absorption in thin-film solar cells, we have textured aluminum-doped zinc oxide (ZnO:Al) films deposited by RF magnetron sputtering on glass substrates using a nanosecond pulsed laser working at 355 nm. The textures have been achieved by simply patterning the ZnO:Al surfaces through direct scribing, using either a linear pattern consisting of equally separated parallel grooves, or a crisscross pattern obtained by performing a second array of laser scribes perpendicular to the former. The relationship between the light scattering properties of the textured films and its morphology are discussed considering two different scattering sources: the pattern formed by the grooves that works as a diffraction grating, and a random roughness of low amplitude created during the laser process. To further characterize the textured samples, amorphous silicon solar cells were deposited onto ZnO:Al films with different textures and their spectral response and short-circuit current (J sc) measured. An increment of 15% in J sc compared to non-textured solar cells is achieved, with ample room for improvement. [ABSTRACT FROM AUTHOR]

Highlights • Laser texturing as a method for Ti-6Al-4V is presented. • Ti-6Al-4V with various macro patterns are produced. • The influence of various patterns on the grinding performance is analyzed. • A series of comparative experiments are conducted on Ti-6Al-4V with/without various micro patterns. Abstract This study investigates the grinding performance of laser textured Ti-6Al-4V surfaces using CBN grinding wheels. The analysis includes examination of the surface topography and chemistry, grinding force, grinding force ratio, surface roughness, grinding temperature, and grinding wheel wear. Six different texturing patterns with the same parameters of groove pitch, depth, and width are designed and compared to non-textured Ti-6Al-4V. The experimental results indicate that laser texturing the surface produces clear reductions in the grinding force of up to 45–56% and the grinding temperature of up to 41–52% compared to the non-textured surface. The optimal effect among the Ti-6Al-4V samples is found when grinding a sample textured with a cross-helix pattern. The results of this study confirm the feasibility of reducing the difficulty in grinding difficult-to-machine Ti-6Al-4V materials through the application of laser texturing. [ABSTRACT FROM AUTHOR]

Laser texturing of Inconel 718 alloy surface under high nitrogen gas pressure is considered and the resulting surface morphology and wetting state are examined. Analytical tools are used to characterize the laser textured surface. Environmental dust particles and liquid solution formed from the water condensate on the dust particles in humid air ambient are analyzed. The tangential force required to remove the dried liquid solution from the laser textured and as received surfaces are measured incorporating the micro-tribomoter. It is found that laser treatment results in micro/nano size pillars on the textured surface and forms nitride compounds on the surface. This, in turn, modifies the wetting state of the workpiece surface from hydrophilic to hydrophobic. A liquid solution is formed due to the dissolution of alkaline and alkaline earth metals of the dust particles into the water condensate in humid air ambient. The liquid solution has high pH and forms different sizes of crystals on the surface upon drying. The liquid solution spreads on the textured surface while forming a film. It adheres strongly to the surface upon drying; in which case, the tangential force required removing the dried liquid from the surface remains high, which is more pronounced for the as receive surfaces. [ABSTRACT FROM AUTHOR]

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The interplay between a prosthetic and tissue represents an important factor for the fixation of orthopedic implants. Laser texturing tests and electropolishing were performed on two materials used in the fabrication of medical devices, i.e., CoCr and Ti6Al4V-ELI alloys. The material surface was textured with a diode-pumped solid state (DPSS) laser and its effect on the surface quality and material modification, under different combinations of laser power and marking speed, were investigated. Our results indicate that an increment of energy per unit length causes an incremental trend in surface roughness parameters. Additionally, phase transformation on the surface of both alloys was achieved. Chemical analysis by energy dispersive X-ray spectrometer (EDX) shows the formation of (Co(Cr,Mo)) phase and the M23C6 precipitate on the CoCr surface; while quantitative analysis of the X-ray diffractometer (XRD) results demonstrates the oxidation of the Ti alloy with the formation of Ti2O and Ti6O from the reduction of the α-Ti phase. The behaviors were both related with an increase of the energy per unit length. Control of the final surface roughness was achieved by an electropolishing post-treatment, minimizing the as-treated values. After polishing, a reduction of surface roughness parameters was obtained in a range between 3% and 44%, while no changes in chemical composition or present phases were observed.

This research investigates the slurry and cavitation erosion resistance of a polytetrafluoroethylene (PTFE) top-coat applied to standalone high velocity oxy-fuel (HVOF) sprayed and laser textured Vanadium Carbide (VC) coating over SS316 steel. The static contact angle, microstructural characterization, EDS mapping, microhardness, fracture toughness, elastic modulus, slurry erosion, and cavitation erosion of all the samples namely SS316, HVOF sprayed VC, Laser textured VC, and PTFE modified VC were evaluated. Results demonstrate that the inclusion of a PTFE top-coat significantly enhances the erosion resistance over HVOF sprayed and laser textured VC coatings. Further, the laser textured VC surface was also found to be successful in reducing the slurry and cavitation erosion of SS316 steel, which could be attributed to its higher microhardness, presence of circular textures, and higher H/E ratio. When the failure mechanism was examined using SEM images, it was found that brittle failure occurred on hard surfaces while ductile failure occurred on soft surfaces. [Display omitted] • Significant improvement in erosion resistance with PTFE top-coat on HVOF sprayed and laser textured VC coatings. • Higher microhardness, circular textures, and higher H/E ratio contribute to improved erosion resistance. • Brittle failure observed on hard surfaces, while ductile failure observed on soft surfaces. [ABSTRACT FROM AUTHOR]

[Display omitted] • Laser texturing enhances slurry erosion resistance of coated and uncoated samples. • HVOF spraying combined with laser texturing creates superhydrophobic surfaces. • Influence of impact angle; maximum mass loss for VC + TiC at 90°, VC-TiC + 50%CuNi-Cr and CuNi-Cr at 30°. Laser texturing method was used in the current study to create a micro-textured surface over SS316 steel with HVOF (High Velocity Oxy-fuel) sprayed VC-TiC and CuNi-Cr based coatings. The static contact angle, cross-sectional characterization, hardness, EDS mapping, surface roughness, porosity percentage, XRD analysis, bond strength and slurry erosion resistance of textured and non-textured surfaces were measured. Slurry erosion experiments were carried out in accordance with ASTM G-73 standards. According to the findings, laser texturing was found as an effective technique for increasing the static contact angle of the surfaces, which in turn increases the slurry erosion resistance of the surfaces. SEM images were used to analyze the failure mechanism, and it was discovered that hard surfaces experienced a brittle mode of failure, whereas soft surfaces experienced a ductile mode of failure. [ABSTRACT FROM AUTHOR]

The human body is an extremely aggressive environment in terms of corrosion. Titanium and its alloys are one of the most popular biomaterials used for implant applications due to biocompatibility. However, every element introduced into the body is treated as a foreign body. The human body’s immune response may, therefore, lead to implant rejection and the need for reoperation. For this purpose, it seems important to carry out surface modifications by applying coatings and inter alia by texturing to implants. The objective of this paper is to investigate the effect of surface treatment on the chosen properties of the pure titanium (Grade II) samples obtained by selective laser melting (SLM) processing. The samples were divided into five groups: Initial state (after polishing), after surface modification by the physical vapour deposition (PVD) method—CrN and TiN coatings were deposited on the surface of the tested material, and after laser texturing. The paper presents the results of the microscopic investigation, chemical and phase compositions, and physicochemical and electrochemical properties of the tested samples. Based on the results obtained it can be concluded that the hybrid surface modification shows significant effects on the properties of the pure titanium. The samples with the textured PVD-deposited TiN coatings were characterized by favorable physicochemical properties and were the highest performing in terms of pitting corrosion resistance.

Enhancement of pool boiling heat transfer can be attained with a number of passive and active techniques. The paper experimentally analyses the impact of laser treatment of the copper surfaces on pool boiling heat transfer of distilled water and ethyl alcohol. The samples were modified with a laser beam to produce longitudinal grooves of highly developed microstructures in the laser textured area. Specimens of different groove depths, groove widths and micro-fin widths were produced. The results indicate a significant influence of laser processing on heat flux dissipated from the surfaces and heat transfer enhancement for all the samples tested. The experimental results have been generalized in the form of a heat flux correlation based on a modified model of enhanced pool boiling heat transfer.

This article features with the enhancement of the static coefficient of friction by laser texturing the contact surfaces of tribological systems tested under dry friction conditions. The high-rate laser technology was applied for surface texturing at unprecedented processing rates, namely using powerful ultrashort pulses lasers in combination with ultrafast polygon-mirror based scan systems. The laser textured surfaces were analyzed by ion beam slope cutting and Raman measurements, showing a crystallographic disordering of the produced microscopic surface features. The laser induced self-organizing periodic surface structures as well as deterministic surface textures were tested regarding their tribological behavior. The highest static coefficient of friction was found of µ20 = 0.68 for a laser textured cross pattern that is 126% higher than for a fine grinded reference contact system. The line pattern was textured on a shaft-hub connection where the static coefficient of friction increased up to 75% that demonstrates the high potential of the technology for real-world applications.

In this research, an investigation on machinability of nickel-based superalloy (Inconel 600) under the influence of textured tungsten carbide cutting tools is conducted. Two main machinability indicators, namely, wear and life, have been investigated. Three types of micro-texture patterns i.e. dimples, lines and splines are laser engraved on the flank face of the cutting tool. Experiments are done with different cutting velocities, feed rate and depth of cut considering the texture pattern one among the input parameters. Firstly, while machining Inconel 600 with plain (non-textured) tungsten carbide cutting tool, it is investigated that at low velocity, the cutting nose caused damage due to abrasion and friction between the tool-chip interface. Severity in tool edge has increased along with adhesive wear and built-up edge at the cutting radius with increase in velocity. Thereafter, using textured on the tools, it is observed that the cutting tool wear resistance has tremendously increased with different textured patterns due to significant reduction in friction and heat. At low velocity (50 m min ^−1 ) the tool wear measured is in the range of 100–150 μ m and maximum of 394 μ m at high cutting velocity of 150 m min ^−1 . The tool life was calculated using Taylor’s equation based on Gaussian method. Tool lives for dimple and line textures are found superior. It is concluded that textured tools have potential to machine hard materials like Inconel superalloys with longer tool life.

The advent of additive manufacturing (AM) is rapidly shaping healthcare technologies pushing forward personalisation and enhanced implant functionalisation to improve clinical outcomes. AM techniques such as powder bed fusion (PBF) have been adopted despite the need to modify the as-built surface post manufacture. Medical device manufacturers have focused their efforts on refining various physical and chemical surface finishing approaches, however there is little consensus and some methods risk geometry alteration or contamination. This has led to a growing interest in laser texturing technologies to engineer the device surface. Herein, several bioinspired micro and nano textures were applied to laser PBF Ti-6Al-V4 substrates to alter physicochemical properties and in-turn we sought to understand what influences these alterations had on a human osteosarcoma cell line (MG63). Significant variations in roughness and time dependent contact angles were revealed between different patterns provide a tool to elicit desired biological responses. All surface treatments effectively enhanced early cell behaviour and in particular coverage was increased for the micro-textures. Influence of the patterns on cell differentiation was less consistent with alkaline phosphatase content increased only for the channel, grid and dual textures. While long term (21 days) mineralisation was found to be significantly enhanced in grids, dual, triangles and shark skin textures. Further regression analysis of all physicochemical and biological variables indicated that several properties should be used to strongly correlate cell behaviour, resulting in 82 % of the 21 day mineralisation dataset explained through a combination of roughness kurtosis and glycerol contact angle. Overall, this manuscript demonstrates the ability of laser texturing to offer tailored cell-surface interactions, which can be tuned to offer a tool to drive functional customisation of anatomically customised medical devices., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)