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The relatively poor antibacterial capability of intrinsic hydrophilic zirconia ceramics limits its wide applications in the field of biological implants. To further exploit and enhance the biocompatibility of zirconia ceramics, a facile silicone oil-assisted laser-heat process was developed to prepare the superhydrophobic zirconia ceramic surface with microcolumn array structure and low surface energy. The characterization results indicated that the micro/nano hierarchical structure was induced by laser texturing on the zirconia ceramic surface, and part of the crystal structure was transformed from tetragonal phase to monoclinic phase. The deposition of carbon-containing hydrophobic functional groups and silicon atoms on the surface was accelerated and the surface energy was significantly reduced by silicone oil-assisted heat treatment. The surface wettability was transitioned from hydrophilicity to superhydrophobicity after the silicone oil-assisted laser-heat process. The bacterial adhesion can be effectively blocked due to the air layer trapped by the surface micro/nanostructures, and the surface antibacterial rate was increased by more than 80%. The ionic corrosion was also slowed down under the combination of the air layer and the reduced solid-liquid contact area on the superhydrophobic surface, which improved the corrosion resistance of the surface. The enhanced antibacterial capability and corrosion resistance on the superhydrophobic zirconia ceramic surfaces prepared by the developed process are expected to provide a key avenue for biomedical applications. [Display omitted] • A laser-based process was developed to fabricate superhydrophobic zirconia ceramic. • Superhydrophobic surface was achieved by altering surface structure and chemistry. • The underlying mechanism of surface wettability transition was analyzed. • Surface antibacterial capability can be enhanced due to superhydrophobicity. • Surface corrosion resistance can be improved due to superhydrophobicity. [ABSTRACT FROM AUTHOR]

Slagging and fouling of boilers are typical technological problems in the combustion of solid fuels (especially coal and biomass). This study proposes a novel approach based on laser texturing of the near-surface layer of steel used to make heating surfaces of coal-fired boilers. This approach is aimed at improving the resistance of metal surfaces to slagging. The formation of slag deposits on the surfaces of AISI 310 S steel modified by laser radiation has been experimentally studied. The formation of slag melt was analyzed on the surface of modified and polished steel plates during heating to 1400 °C. High-temperature heating and interaction with slag led to a change in the chemical composition of the steel. A significant increase in the chromium content (up to 47%) of the steel surface and the transformation of its texture with the formation of grains up to 2.5 µm in size were established. Laser surface treatment significantly increased the resistance of the steel to such changes and also reduced the grain size to 1.5 µm. As a result of laser modification of surfaces, the temperature of slag formation shifts to higher values (higher by 60–75 °C compared to the unmodified polished surface). The anisotropic texture (cauliflower type) contributed to a decrease in the size of the slag spreading front, and also had by self-cleaning properties from the mineral melt. The latter allows to increase the reliability and energy efficiency of boiler equipment. [Display omitted] [ABSTRACT FROM AUTHOR]

Self-powered sensors detect a variety of crucial parameters for industrial processes without any external power source for Industry 4.0. It has capabilities to acquire, analyze, and make decisions on real-time data, these sensors are essential for the advancement of automated production systems and smart factories. In this regard, Triboelectric nanogenerators (TENGs) have potential to provide effective solution as self-powered vibration sensor for continuous monitoring of machine tools. Different techniques have been used to enhance the performance of TENG such as material doping, chemical etching, ion injection, etc. However, laser surface texturing is a low-cost, contact less, efficient technique which can be used for improving the response of TENG-based self-powered vibration sensors. In this context, Laser Induced Backside Texturing is a laser micro texturing approach to improve the electrical performance. It induces waviness and surface roughness, which leads to increased surface charge density and triboelectrification capabilities. In this work, laser micro texturing was performed using with 405 nm wavelength semiconductor diode laser to generate line pattern texture on the Fluorinated Ethylene Propylene (FEP). Laser textures TENG (LT-TENG) was developed with laser textured FEP as tribonegative material and pristine Aluminium as tribopositive material, the open-circuit voltage, short-circuit current and power density achieved 23 %, 41 %, and 47 % enhancement respectively, generating 794 V, 44 µA, and 2371.6 µW/cm2. This increase in output leads to an increased sensitivity of the sensor. When mounted on the machines, LT-TENG was able to detect their working state, vibration frequency, and harmonics i.e. 46, 92, 184 Hz for the vacuum pump and 140, 280, 410 Hz for the heat gun. These detected vibration frequencies, and their harmonics were similar to the frequencies detected by the commercial accelerometer (CTC AC115), confirming potential use of LT-TENG as a low-frequency vibration sensor. The developed LT-TENGs was integrated with the Internet of Things (IoT) supported microcontroller, which collects real-time data for continuous monitoring and analysis for machine health monitoring in smart devices. [Display omitted] • IoT-enabled Laser Textured TENG-based Self Energizing Vibration sensor is presented. • Single Triboelectric Nanogenerator acts as energy harvester and vibration sensor. • Laser Textured TENG have shown notable 41 % enhancement in current. • Laser Textured TENG improves the sensitivity towards vibration sensing. [ABSTRACT FROM AUTHOR]

Nanocelluloses are emerging as natural materials with favourable properties for coating industry and can be applied by state-of-the-art spraying technology. While additional functionalities are commonly introduced through chemical modification, the surface microstructuring of nanocellulose coatings with high throughput methods remains unexplored. Here, a femtosecond laser is used for texturing spray-coated coatings made of cellulose nanofibrils (CNF) or cellulose nanocrystals (CNC). For coating thickness of 1.5 to 8 μm, processing limits were determined with maximum ablation energy linearly increasing with coating thickness and minimum ablation energy decreasing or increasing depending on the apparent coating density. Within applicable processing window of pulse rate and power setting, the operational ranges were determined for creating one-dimensional and two-dimensional surface patterns, requiring a higher laser energy for CNC compared to CNF coatings and yielding thinnest possible resolved patterns of 17 μm as determined by the laser spot diameter. The laser ablation under low energy corresponds to an increase in surface roughness and intensifies surface hydrophilicity, while the line patterns are able to pin water droplets with rising water contact angles up to 90°. Present feasibility study opens future possibilities for managing surface properties of nanocellulose coatings in applications where tuning of surface hydrophilicity is required. [Display omitted] [ABSTRACT FROM AUTHOR]

• Laser texturing improved the laser actuation performance of nitinol shape memory alloy. • Textured nitinol showed significant improvement in actuation performance due to enhanced optical absorbance. • Influence of single- and two-stage texturing on actuation performance of nitinol was explored. • Improvement in actuation performance was demonstrated for continuous wave fiber and CO 2 lasers. Laser surface texturing of nitinol was performed using a nanosecond fiber laser to modify the surface structure and enhance the laser actuation performance of nitinol. The influence of laser processing parameters on surface morphology and chemical composition was studied in detail. The influence of texturing on the laser actuation behavior was evaluated using a continuous wave fiber laser and a CO 2 laser. Compared to the pristine sample, the textured samples demonstrated better displacements and faster actuation. During laser actuation using a fiber laser, the textured sample showed maximum and minimum displacement enhancements of 65% and 15%, respectively. The actuation performance of the textured sample was approximately twice that of the pristine sample during the irradiation with CO 2 laser. This paper presents the viability of laser surface texturing to enhance the actuation performance of shape memory alloys, and the results indicate that the power required for actuation can be reduced to avoid the use of bulky power and control units. [ABSTRACT FROM AUTHOR]

Excessive friction encountered during the sliding of mechanical pairs usually causes detrimental effects on both the component surfaces and their performance. Elevated contact stresses owing to high friction lead to increased wear and shortened service lifetimes. To mitigate this issue, this study explored a solution involving a surface modification of AISI M2 tool steel. The approach included a titanium nitride (TiN) coating and the laser texturing of a rectangular array of micro-dimples on the metal surface. The effect of laser texturing parameters on dimple size was investigated, and the use of 8-W laser power together with 0.1-second irradiation duration was able to fabricate the desired dimple size to enhance the lubrication. The influences of the dimple density on the coating adhesion, wettability, friction, and wear of laser-textured surface were also examined. The coating adhesions of the untextured and textured TiN-coated surfaces were not significantly different. The textured surface exhibited oleophilic behavior, and oil was more likely to spread on the surface with a higher dimple density. Under a load of 50 N, the surfaces with dimple densities of 5 % and 9 % exhibited low friction compared to the untextured surface. Wear was found to be low on the textured surface due to the enhanced lubricating effect and improved load-carrying capacity. Additionally, the empirically derived Archard wear coefficients showed non-linear wear behavior throughout the sliding length. The obtained results evidence that the laser texturing is feasible for improving tribological performance of the low friction-coated high-speed steel surfaces. • Laser texturing with rectangular array of micro-dimples reduces friction and wear of TiN-coated AISI M2 steel. • The use of 8-W laser power and 0.1-second irradiation duration can fabricate desired dimple size for enhanced lubrication. • Dimple density influences friction, wear, and wettability, except for the coating adhesion of the laser-textured surface. • The empirically derived Archard wear coefficients exhibited non-linear wear behavior of the laser-textured surface. • Textured surface exhibits oleophilic behavior and improved load-carrying capacity. [ABSTRACT FROM AUTHOR]

• The surface topography of laser-textured cross-hatched materials was studied. • The results of roughness measurement using the contactless WLI method were analysed. • A procedure to mitigate the influence of high-frequency noise was proposed. • The noise was characterised by autocorrelation, power spectral, and direction functions. • The procedure was validated by studying the laser-texturing direction in profile data. The precision of surface roughness determination using ISO 25178 parameters relies on various factors that directly impact the measurement process. In industry applications, the contactless roughness measurement reduces data collection time. However, it introduces several potential errors, including those stemming from the environment. One of the main types of errors encountered during topography analysis is measurement noise, which arises from different external disturbances. High-frequency noise is particularly studied as a result of vibration. In the present study, the laser-texture cross-hatched surface topographies were analysed using the results obtained from white light interference measurements. Measurement noise was defined based on noisy data, also called noise surface, which is the result of filter decomposition methods. This data separation technique was supported with power spectral analysis, autocorrelation function applications and texture direction characterisation. It was suggested to conduct a comprehensive study of the noisy data to enhance the understanding of texturing direction. Various data filtration techniques were studied, namely robust Gaussian, spline, fast Fourier transform and morphological closing-opening filters. The results of the proposed procedure were validated against variations in the values of ISO 25178 surface texture parameters. Validating the proposed approach, the variations of noise-sensitive surface texture parameters were compared to the variations of the same parameters but received by averaging three repeated measurements, as proposed by international standards. The main advantage of the proposed method against standards procedure was reducing the time of data collection when the measurement must be repeated and averaged. In conclusion, a method for reducing high-frequency measurement noise was introduced through the application of the proposed procedure. [ABSTRACT FROM AUTHOR]

[Display omitted] • LIPSS with a periodicity of 270 nm can reduce adhesion of E. coli in more than 35 %. • LIPSS periodicity is a key factor in bacteria adhesion process. • LIPSS with the greatest depth (highest SDAEs) favour E. coli adhesion in every case. • LIPSS with a periodicity higher than bacterial size favour biofilm formation. • Same LIPSS can lead to differences in bacterial adhesion depending on wettability. Bacterial adhesion is a serious problem in the healthcare and food industries, causing health problems and economic losses. This study evaluates the generation of Laser-Induced Periodic Surface Structures (LIPSS) with different periodicities to reduce bacterial adhesion on ferritic stainless steels. LIPSS nanostructuring evolves from hydrophilic to hydrophobic with air exposure. Fresh samples with 870 nm LIPSS show nearly 50 % reduced E. coli adhesion, but this effect diminishes in stabilized samples. This effect on bacterial adhesion can be attributed to LIPSS periodicity being like bacterial size, which would allow bacteria to accommodate and provide a suitable environment for their adhesion. Our results show that, in stable samples when the LIPSS periodicity is around 400 nm, reductions by almost 30 % are achieved and this reduction reaches 35 % when periodicity is close to 270 nm. These results indicate that smaller spatial periods prevent bacteria from fitting into valleys, so they remain on the peaks, hindering bacterial adhesion. Additionally, deeper LIPSS produced by a higher Surface Density of Applied Energy (SDAE), enhance bacteria-material interaction and, thus, increases adhesion. [ABSTRACT FROM AUTHOR]

Surface modification is assuming a strategic role for interface properties tuning, either in the case of interaction between implant and tissue or substrate and coating. However, sometimes a lack of integration between a comprehensive implant surface characterization and, for instance, biological phenomena occurrence can be detected, dealing with inherently different fields of study. This work aims to provide a suitable approach that could allow correlation between substrate features and surrounding environment alterations, whether it biological or not. A chain of characterization techniques and their role within the research path will be explored employing a case study: biomedical Ti6Al4V titanium alloy treated with ultra-short laser for surface texturing and its features and interactions with a natural polymer-based composite as a potential coating. [ABSTRACT FROM AUTHOR]

The use of lasers to fabricate micro-textures on the surface of medical implants is an effective method to improve their bio-tribological properties. In the present study, three distinct configurations of micro-textures, namely, co-axial circles, hexagon, and line with varying spacing of 300 µm, 400 µm, and 500 µm, were fabricated on Ti3Al2.5V alloy using Nd:YAG fibre lasers. The influence of micro-textured geometries on microhardness, coefficient of friction (COF), and wear rate was estimated. The tribological properties of the polished and textured samples were investigated using a linear reciprocating tribometer against silicon nitride (Si 3 N 4) balls under simulated body fluid (SBF) lubricant. Orthogonal results indicate that the co-axial circles with a spacing of 305 µm prove to be the most efficient in enhancing the tribological performance of textured surfaces. This configuration demonstrates a significant improvement, with a 33.62 % reduction in friction coefficient and a 61.81 % reduction in wear rate compared to polished samples. The decrease in spacing appears to enhance the anti-friction and anti-wear properties of the textured surfaces. The working mechanism behind the reduction in the friction coefficient and wear rate lies in the capacity of the textures to trap particles. • Laser surface texturing (LST) of Ti3Al 2.5 V surface: co-axial circles, hexagon and line texture. • Tribological behaviour of the various configurations with spacing of 300 µm, 400 µm, and 500 µm was studied under lubricated conditions. • The friction and wear reduction for various textures varies. • Texture spacing has a remarkable effect on the tribological properties. [ABSTRACT FROM AUTHOR]

• Ti6Al4V systems were produced by laser surface texturing and hydrothermal treatment. • Physicochemical features of Ti6Al4V systems with pyramid micropillars were profiled. • Ti6Al4V systems demonstrated adequate mineralization performance compared to SLA. • Ti6Al4V systems can potentially enhance bone-implant interactions. New orthopaedic implant designs, coupled with tailored surface enhancements, strive to accelerate initial bone formation by enhancing the interface with the adjacent bone tissue. In this study, we report the conceptualization and in vitro testing of Titanium 6-Aluminium 4-Vanadium (Ti6Al4V) systems, focusing on the formation of a pyramid-inspired architectural structure integrating the precision of laser surface texturing with hydrothermal treatment and biofunctionalization with human fibronectin. This configuration features micro-scaled pillars with uniform width and height, accompanied by grooves of diverse dimensions, providing spatial confinement for human mesenchymal stem cells (MSC). Textured Ti6Al4V systems were profiled in terms of physicochemical characteristics (surface roughness, chemical composition, crystalline structure, and wettability) and in vitro mineralization capacity in comparison with conventional sand-blasted, large-grit, acid-etched (SLA). Notably, textured Ti6Al4V systems exhibited robust MSC adhesion, and their mineralization capacity was on par with, or even exceeded, that of the SLA Ti6Al4V surfaces. Together, the findings presented in this work indicate that engineering pillar micro-structures with controllable dimensional features coupled with hydrothermal treatment and fibronectin coating is a promising strategy to modulate MSC activation for potential enhancement of osseointegration. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate novel laser-treated structures designed to improve the adhesion performance and corrosion resistance of AA7075-T6 bonded joints. The spacing, position, and surface area parameters of the laser-treated grooves were investigated to understand their role in adhesion performance even under corrosion conditions. Laser-treated surfaces were analyzed using microscopic, topographic, and chemical methods to determine their scientific contribution to adhesion and corrosion performance. Laser-treated adherends were also bonded to mechanically test their bond strength both before and after exposure to corrosion for varying periods of time. Roughness and therefore surface area have a significant effect on adhesion performance; however, it is worth noting that the best adhesion performance both before and after corrosion exposure was achieved when the required surface area was properly designed and, laser treated according to the salt water exposure directions to inhibit its diffusion into the adhesion interface. The performance of the novel laser-treated structures in terms of adhesion performance under corrosive atmosphere was also supported by failure analysis. The mixed failure mode was significantly shifted to the cohesive failure mode, especially for bonded joints with box-type laser-treated structures. [Display omitted] • Reducing groove spacing resulted in an increase in surface area and bond strength. • Novel laser-treated structures resulted in significantly more surface area. • Deeper grooves positively affected the adhesion strength and corrosion resistance. • Direction of the grooves had an important effect on the inhibition of salt water. • Box type structure had an optimum adhesion strength even under corrosion exposure. [ABSTRACT FROM AUTHOR]

Titanium (Ti) alloy is vulnerable to erosion and corrosion effect of sea water in the application of marine equipment and prone to degradation and failure. In order to further enhance the erosion-corrosion resistance of Ti alloy, a laser-heat hybrid treatment is applied to fabricate superwetting Ti alloy surface. The surface morphology, chemical composition and surface wettability of Ti alloy before and after laser processing are characterized. The surface behaviors of the superwetting Ti alloy surface during corrosion and erosion-corrosion interaction are evaluated by electrochemical station and two-phase flow erosion equipment. The experimental results indicate that the periodic micro-bump structure induced by laser texturing and the low surface energy after heat treatment contribute to the surface wettability transformation into superhydrophobicity with the contact angle of 156.2°. Compared with the untreated Ti alloy surface, the laser-heat-treated superhydrophobic surface exhibits a smaller corrosion current density and a larger potential in NaCl solution, showing better corrosion resistance. The surface erosion-corrosion resistance has also been increased by 18% due to the decrease of solid-liquid contact area caused by air cavity of superhydrophobic surface. This can provide a solid laser-based fabrication method of Ti alloy for long-term and stable application in marine environment. [Display omitted] • Laser-heat hybrid treatment was developed to fabricate superwetting Ti alloy. • Superhydrophobic surface was achieved by altering surface structure and chemistry. • Corrosion resistance can be significantly enhanced due to superhydrophobicity. • Erosion-corrosion resistance was distinctly improved after laser-heat treatment. • The mechanisms of corrosion and erosion-corrosion interaction were analyzed. [ABSTRACT FROM AUTHOR]

The present work seeks to develop a novel and systematic approach to quantifying the repeatability of textured surfaces, a relevant property for several technological fields. Specifically, aluminum alloy and stainless steel specimens were subject to nanosecond pulsed laser texturing to produce arrays of ablation craters in a typical configuration employed to improve wettability and tribological performance. Feature repeatability was firstly assessed in terms of crater volume and interfacial area, after which an additional parameter was developed based on the Pearson's Correlation Coefficient (PCC). Within the tested laser parameter range, the crater volume exhibited highest repeatability in the high energy dose regime on aluminum alloy specimens, while the crater volume was more repeatable in the low energy dose regime on stainless steel specimens. This difference was attributed to the development of an oxide ring surrounding the craters on stainless steel at high energy dose. This outcome was confirmed through analysis of the point-to-point repeatability, where process repeatability was determined for different portions of the ablation craters. • Surface metrology provides useful tools to study the process repeatability. • Repeatability of laser processed craters depends on the energy dose irradiated. • Surface height, area and void volume may have different repeatability. • Process surface repeatability varies point-to-point within the same processed area. [ABSTRACT FROM AUTHOR]

Pulsed laser-based micro-texturing induces topographical and chemical modifications on surfaces that yield beneficial properties such as anti-microbial effect, micro-hydrodynamic bearing, and surface hardening. These properties find a multitude of applications in surface treatment and tribology. However, laser texturing of free form surfaces is a cost and effort-intensive process, specifically medical implants or ergonomically designed tools/devices. Such components often require numerically controlled 3 or 5 axes machines and sophisticated computer-aided manufacturing (CAM) software for precise tool movement. In this manuscript, the authors have designed, fabricated, and validated a jerk-free, cost-effective Stewart platform that works in tandem with an existing laser machining setup. A microcontroller and stepper motor based linear actuators were used to orient and translate the six degrees-of-freedom (DoF) platform. A customized computer program helped maneuver the workpieces (medical implants) for the micro texturing of the 3D surface profiles. As laser irradiation demands a time-invariant focal length for effective ablation, the platform maintains the focal length from the galvo-scanner of the laser machine to the workpiece while maneuvering the workpiece throughout the texture trajectory. To estimate the smoothness of the platform during motion, vibrational parameters were also measured and analyzed. Such cost-effective platforms may find applications in free form texturing in non-contact mode of machining as well as in metrology. Texturing was performed successfully on implants freeform surface with an average diameter of ~35–40 μm and depth of ~15–20 μm. [Display omitted] • A cost-effective Stewart platform was designed for freeform texturing of implant. • Jerk-free 3D maneuvering with ±25 μm tolerance was achieved by customized program. • The platform works in tandem with an existing laser machining setup. • 6 degrees-of-freedom was achieved using a microcontroller and linear actuators. • Electrochemical studies showed improved corrosion resistance post texturing. [ABSTRACT FROM AUTHOR]

Zirconia (ZrO 2) incorporated ceramic coatings were fabricated on biodegradable ZM21 Mg alloy by the PEO coupled with EPD process. Subsequently, the sample surface was modified by laser texturing to improve the corrosion resistance, roughness and cell proliferation and growth properties. The corrosion performance of the fabricated samples along with the substrate was studied by electrochemical measurements under simulated body fluid (SBF) environment. The cell direct contact assay was conducted for the substrate and fabricated samples using L -929 mouse fibroblast cells for 24 h. The phase contrast images of cell direct contact assay revealed that fabricated samples exhibited better contact and response with the fibroblast cells, compared to the substrate. The addition of nanoparticles in the PEO process, called PEO coupled EPD process, resulted in attaining a higher thickness and improved corrosion performance of the samples than the PEO coated samples. Among all the samples, laser surface textured PEO, and PEO-EPD coated samples unveiled enhanced corrosion resistance, cell growth, thereby enabling it as a suitable prototype for biodegradable implant applications. [ABSTRACT FROM AUTHOR]

Ceramics have been widely used in the field of tribology due to their superior corrosion resistance and low friction coefficient. The tribological properties of ceramics can be improved by machining proper surface texture. This work uses a nanosecond laser to process dimples on different ceramic surfaces. The morphology and size of dimples as a function of the number of laser shots and laser power are investigated. A theoretical model relating laser parameters and dimple size is established. In the initial point contact friction test, based on the experimental parameters mentioned in this paper, the existence of surface texture reduces the wear volume of Si 3 N 4 balls in water by 41.5% and the wear volume of ZrO 2 balls in oil by 51%. [ABSTRACT FROM AUTHOR]

• Micro-texture under different texturing direction had different effect on joint. • Stress at the TC4/CFRTP interface was simulated. • Different Micro-texture provided different mechanical resistance during tensile test. Hybrid structure of titanium alloy and carbon fiber reinforced thermoplastic composite (CFRTP) provided a new direction for lightweight and laser had a great prospect for application in joining metal/plastic. In this work, before laser joining TC4 (Ti6Al4V) and CFRTP (PA66), three groove micro-structures in different texturing direction (0°, 45°, 90°) were prepared on the TC4 surface respectively by nanosecond laser. The effect of different groove texturing was studied. Research results showed that the existence of three groove texturing increased the affinity between TC4 and molten CFRTP to the same extent. The resin-carbon fiber mixture adhered to the surface of TC4 after laser texturing increased obviously. However, the groove micro-structure had different impact on the tensile performance of the joint. The maximum tensile shear strength could reach 10.9 MPa, which was increased by 111 % compared with the untreated when the groove micro-texturing direction was perpendicular to the tensile direction (0° texturing) while the 90° textured joint performance was only increased by 42.9 %. The FEA results revealed that micro-texturing provided mechanical resistance for the joint during the tensile process and 0° micro-texturing provided the largest mechanical resistance followed by 45° and 90° micro-texturing. [ABSTRACT FROM AUTHOR]

[Display omitted] • The friction-assisted joining technique was adopted to join the AA7075 sheet to the PEEK sheet. • Different laser surface treatments were carried out to increase joint strength. • Laser cleaning enabled the jointing of AA7075 to PEEK. • Laser texturing significantly increases the adhesion strength (+30%). • The two-step laser treatment, texturing + cleaning, results in a further increase in strength (+39%). The present study investigates the adoption of laser surface treatments to improve the bonding strength of dissimilar material hybrid structures made by the thermomechanical joining process. Aluminium AA7075 alloy was joined to Polyether-ether-ketone through a friction-assisted joining process. For the surface treatment, a two-step laser treatment was adopted. The latter consists of a first phase, called laser texturing, where a deep square grid texture is obtained by adopting high pulse energy and repetitions, followed by a further laser treatment, called cleaning, carried out with lower energy content, and applied over the overall adhesion surface. Two textures characterised by different grid sizes (200 and 300 µm) were realised. As received, uncleaned, and only cleaned samples were adopted as reference treatments. The results indicated that laser cleaning performed after laser texturing enabled a significant improvement of adhesion irrespective of the previous laser texturing strategy. This was also confirmed by the higher amount of polymer trapped within the laser-texturized paths. The only laser cleaning treatment enabled the successful joining of the substrates with an average shear strength of 12 MPa. On the other hand, when texturing with a hatch distance of 200 μm, laser cleaning performed after texturing increased the shear strength from 18.4 MPa to 25.2 MPa corresponding to an increase of 37%. The increased adhesion between the PEEK and the aluminium was also indicated by the change in the failure mode of the joints. The texturized samples with a hatch distance of 200 μm failed by pull-out; when the laser cleaning was performed on these samples, they failed by cohesive failure. [ABSTRACT FROM AUTHOR]

• Laser welding of TC4 to CFRTP was assisted by surficial micro-arc oxidation and mirco-texture. • Micro-arc oxidation and mirco-texture improved wettability of CFRTP on Ti surface. • Support Vector Regression model was adopted to optimize welding parameters. Laser texturing and MAO (micro-arc oxidation) hybrid process was adopted to enhance the tensile-shear strength of laser welded CFRTP/TC4 joint. Introduction of porous MAO coating enhanced wetting ability of molten peek from CFRTP and increased surface roughness. Porous structure could also provide a mechanical interlocking effect in CFRTP/TC4 interface and improve the resistance to tensile-shear load. Highest tensile-shear force of 1587 N was obtained when 2.3 μm MAO coating was prepared. Based on this, influence of various laser texturing patterns with different MAO coating thickness on the tensile-shear forces was clarified by combination of experiment and reasonable SVR (Support Vector Regression) model. Maximum predicated surface roughness of 3.075 mm was produced at texturing width of 0.327 mm, texturing depth of 100.54 μm and MAO duration of 1.667 min. Furthermore, highest predicated tensile-shear force of 2995.1 N was achieved at texturing width of 0.331 mm, texturing of depth of 100.6 μm and MAO duration time of 1.718 min. [ABSTRACT FROM AUTHOR]

High-performance polymer cold-spraying is attracting the interest of many for its economical, time-saving, and environmentally safe features in comparison to traditional thermal spraying processes. The cold spray process allows applying functional polymer coatings on a similar or dissimilar material surface for protective measures or additional functionalities. However, its practical use has been restricted by inherently low deposition efficiency associated with a weak interfacial adhesion strength. In this study, fluoropolymer powder mixed with 5 wt% of nano-alumina was cold-sprayed on laser-textured carbon steel substrates. A thorough analysis of the particle deposition as a function of the spray parameters (gas temperature, pressure, pass number, traverse speed) was performed to highlight the effect of the laser-texturing (groove geometry, laser pitch, pattern) on the deposition efficiency and adhesion strength. By laser-texturing the substrate, the deposition efficiency increases up to 60 %, and the adhesion strength reaches 1.25 MPa. Thus, while the addition of nano-alumina enhances the interparticle cohesion, a laser-textured substrate promotes the mechanical interlocking at the particle/substrate interface. • Laser texturing of the substratesurfaceincreases the deposition efficiencyof polymer powder. • Deposition efficiencyof PFA reaches 60 %. • Laser texturing allows strongmechanical interlocking at the interfacemetal/coating interface. • The increase of the gas temperature enhances the adhesion strength. [ABSTRACT FROM AUTHOR]

Despite the reported high success of dental implants, problems related to biofilm formation and peri-implantitis due to the entrance and proliferation of bacteria on the peri-implant zone have increasing attention. In this sense, this work proposes a new zirconia surface with micro-grooves aiming to develop an effective tight seal between artificial soft tissue and implant surface and thus, to protect from bacterial invasion. In this study, different laser and design parameters were tested to produce successive micro-grooves with different and variated depth, width and wall. The micro-grooves were produced by a Nd:YAG laser and were morphologically characterized by SEM. Higher marked depths were obtained for a high number of laser passages under low scan speed as a result of a high amount of laser energy density. The most adequate conditions were mechanically tested regarding their capacity to retain artificial soft tissue (mimicking natural gingiva) by mechanical tensile strength test. The strength of adhesion between soft tissue and the micro-grooved surface revealed to be strongly dependent on the depth and width. The obtained results showed that the production of successive micro-grooves on the zirconia surface increased the adhesion of artificial soft tissue to its surface, proving that laser technology is a promising approach for the manufacturing of implants with micro-grooves sites that can protect from bacterial invasion. [ABSTRACT FROM AUTHOR]

Laser dimple generation can functionalise ceramic surfaces. Dimple characteristics determine the functionalised surface properties, which has numerous applications. Laser parameters and material properties are key factors in the design of the dimple features. Pulse energy, E p, and average surface roughness, Ra, are important parameters in the dimple production. Thus, the influence of the E p of InfraRed (IR) nanosecond pulsed laser on the dimple characteristics generated on two Cr 2 O 3 surfaces (as-received and polished) are studied in this work. The increase of the E p increased the dimples features (Diameter, D, and depth, L). Polished surfaces gave dimples with increased depth while dimples produced on as-received samples were shallow. The energy fluence ablation threshold, φ th, is higher for as-received surface than for polished Cr 2 O 3. [ABSTRACT FROM AUTHOR]

Performance of crystalline Silicon solar cells depends on numerous factors. One key factor is a surface structure which can restrict electrical and optical properties due to recombination of generated carriers and reflection of incident light. Surface texturing reduces reflection from a flat surface which increases absorption of light. Anisotropic alkaline etchants are commonly used for texturing mono-crystalline Silicon wafers which produce pyramid structures on the surface. Because of randomly oriented crystallographic grains, this method is not feasible for multi-crystalline Silicon wafers. Here, an alternative texturing process using a laser system is proposed. Laser beam creates vertical and horizontal grooves on the surface in which the intersections are for a light trapping purpose. Laser parameters are determined experimentally to have the lowest reflection. Next, chemical post-texture cleaning is performed to remove laser-induced damages and other residues. Finally, samples went through general solar cell fabrication steps. For characterizations, weighted reflection is measured and correlated with Scanning Electron Microscopy images of a textured surface to evaluate the performance of texturing and post-texture cleaning. To examine fabricated solar cells' performance, I–V curve and External Quantum Efficiency are measured. Results indicate that proposed processes lead to an improved efficiency compared to reference samples. • Optimizing laser texturing as an isotropic texturing method by optimizing laser parameters. • Optimizing post-texture cleaning method using KOH solution with proper parameters. • Fabricating solar cell based on optimum laser texturing and post-texture cleaning parameters. • Achieving considerably low weighted reflection by laser texturing and depositing ARC. • Improving conversion efficiency of conventional c-Si solar cell comparing to reference cell. [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]

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]

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]

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]

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]

• 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]

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]

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 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]

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]