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• 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]

• 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]

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]

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]

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

Laser surface texturing of Inconel 718 alloy is carried out under the high pressure nitrogen assisting gas. The combination of evaporation and melting at the irradiated surface is achieved by controlling the laser scanning speed and the laser output power. Morphological and metallurgical changes in the treated surface are analyzed using the analytical tools including optical, electron scanning, and atomic force microscopes, energy dispersive spectroscopy, and X-ray diffraction. Microhardnes and friction coefficient of the laser treated surface are measured. Residual stress formed in the surface region is determined from the X-ray diffraction data. Surface hydrophobicity of the laser treated layer is assessed incorporating the sessile drop method. It is found that laser treated surface is free from large size asperities including cracks and the voids. Surface microhardness increases significantly after the laser treatment process, which is attributed to the dense layer formation at the surface under the high cooling rates, dissolution of Laves phase in the surface region, and formation of nitride species at the surface. Residual stress formed is compressive in the laser treated surface and friction coefficient reduces at the surface after the laser treatment process. The combination of evaporation and melting at the irradiated surface results in surface texture composes of micro/nano-poles and pillars, which enhance the surface hydrophobicity. [ABSTRACT FROM AUTHOR]

• Micro-grooves with designed spacings and depths are prepared by UV laser surface texturing of PVA hydrogels. • The laser textured micro-grooves enable the effect of "drainage channel" and interlocking at the hydrogel-titanium alloy friction pair interface. • A friction model of interlocking and ploughing has been proposed to explain the behavior of hydrogel micro-grooves against titanium alloy surface. • The shape, size and distribution of micro-groove array are the designable variables for regulating the friction stress in hydrogel-solid interfacing applications. Hydrogels have exhibited extremely complex tribological behaviors. Although various physical mechanisms have been proposed to explain their tribological behaviors, it is still a challenge to develop convenient and efficient regulation methods for tribological behaviors. We propose micro-grooves with different depths and spacings prepared on the PVA hydrogels surface by ultraviolet laser texturing to provide an effective method for understanding the tribology of hydrogels. At the sliding velocity range of 0.085 mm/s < v less than 2.3 mm/s, the effect of interlocking and ploughing force between the direct contact interfaces are the dominant origins of friction. Frictional stress increases when the spacing of the micro-groove getting smaller as the frequency of interlocking getting higher. Interestingly, frictional stress doesn't increase with increasing micro-groove depth. Once the velocity exceeds to 6.9 mm/s, all the micro-grooves begin to wear and fracture, and the results of the frictional test become inaccurate. Smooth hydrogels without any micro-grooves enter elasto–hydrodynamic transition at the lowest velocity, which have minimum friction stress. These results take us a step closer to deriving a more effective, accurate, and dependable guideline for sliding friction control in hydrogel applications. [ABSTRACT FROM AUTHOR]

• Femtosecond laser induces LIPSS, SWPSS and microporous structure on Zr-based amorphous.. • Compare the period, amplitude, surface fluctuation and roughness of different micro-nano structures. • The effective energy density increases, LIPSS transitions to SWPSS, and finally into a self-organized microporous structure.. • The micro-remelting caused by the heat accumulation effect is the key to the transformation of the micro-nano structure. • The self-organized microholes structure has the great ability to reduce E. coli adhesion. Laser induced micro-nano texture formation on the surface of solid materials has become a research hotspot in the field of material surface modification. However, due to its extremely easy crystallization characteristics, the study of laser-induced surface modification of bulk amorphous alloy lags behind. In this study, femtosecond laser was used to induce one-dimensional LIPSS (Laser-induced periodic surface structures), SWPSS (Super-wavelength periodic surface structure), a mixed state structure of LIPSS + SWPSS and two-dimensional self-organized microholes structure on surface of the Zr55Cu16Ni15Ti10Al4 bulk amorphous alloy. The numerical difference between LIPSS, SWPSS and self-organized microholes structure in different dimensions such as period, groove width, profile height, etc. were compared, and the roughness of different micro-nano textures and the size of surface undulations were evaluated. The effects of different process parameters on the formation and transformation of micro-nano texture on the surface of zirconium bulk amorphous alloys were investigated. The mechanism of the transformation from LIPSS to SWPSS and finally to two-dimensional self-organized microholes structure was analyzed in detail. Finally, Escherichia coli was cultured on the amorphous surface of Zr-based metallic glasses with different structure. To examine the effect of micro-nano texture on the antibacterial properties of Zr-based metallic glasses surfaces. It is found that the self-organized microholes structure has the best effect in reducing the adhesion of bacteria on the surface of the material. [ABSTRACT FROM AUTHOR]

• Investigate effect of various widths of laser textured groove on the joint. • Identify a new chemical bonding MgCO 3 at the interface after joining. • A number of AZ31B matrix was observed on the CFRTP at the interface. • The joints broke at the CFRTP base material after laser texturing. Laser texturing was performed on the surface of AZ31B magnesium alloy to increase the bonding strength. Textured AZ31B and carbon fiber reinforced thermoplastics (CFRTP) were then joined by the hot-pressing joining process. The effect of various groove widths of laser textured grid on the AZ31B/CFRTP joint was investigated. The research results showed that the wettability of the molten CFRTP on laser textured AZ31B was increased by about nine times, and the contact angle was reduced from 104.0° to 48.8° with a groove width of 0.3 mm. The macroscopic morphology and interface of joints had no defects, when the groove widths were 0.2 mm and 0.3 mm. The tensile-shear test was carried out, and the maximum tensile-shear force of the joint was 2698.8 N in the case of 0.3-mm groove width, which was 2.1 times as much as that of the untreated joint. The maximum tensile-shear force was 65.43% of the CFRTP itself. A diffusion layer of 9 μm– 24 μm thick formed at the AZ31B/CFRTP joint. MgCO 3 was identified at the joining interface. The mechanical interlocking and chemical bonding formed at the interface effectively improved the strength of the joint. [ABSTRACT FROM AUTHOR]

Abstract: Laser texturing is a novel technique that may be used to texture a cold roller in the process of manufacturing high quality steel sheets. With the aim of improving the quality of the textured roller by using a CO2 laser, a new laser beam modulating device is proposed. An optical beam expander with a fast rotating chopper system is designed. The laser pulse is split into two parts by the chopper blades; one is the preheating pulse that is reflected onto optical loop mirrors; the other is the directly transmitted pulse that creates the craters at the preheated spots. The preheating beam focus spot size and position can be adjusted. The focusing characteristics and optical parameter compensation for the flying optics are investigated. The heat transfer and melt process of laser texturing are numerically simulated. The effects of the double pulses on the texturing are analyzed. The effect of preheating the sample ahead of the laser texturing pulse is examined. The surface profile and bump hardness show improvements by using this approach. [Copyright &y& Elsevier]

• Laser texturing expanded the contact area of substrate. • Laser texturing increased the surface roughness (Ra and Rz). • Laser texturing improved the adhesive strength significantly. • The mechanical interlocking was discovered. The effect of laser process parameters including single pulse energy (E), dimples per square millimetre (D) and laser incidence angle (θ) on the properties of 30CrMnSiA steel substrate and the tensile shear strength of adhesively bonded joints was investigated. The characterization of the substrate was established by surface morphology, the dimension (diameter and depth) of dimples and surface roughness (Ra and Rz). Single lap joints were fabricated and tensile tests were then performed. The fracture surfaces were observed and analyzed. The results indicated that the dimple dimension and surface roughness increased as the single pulse energy increased. The increase of dimples per square millimetre made surface roughness improve. The larger incidence angle reduced the actually absorbed energy changing the shape and size of dimples. The diameter of dimples increased while the depth decreased as incidence angle increased. The modified substrate morphology as well as increased dimple dimension expanded the contact area between the adhesive and adherend. The shear strength was enhanced and the maximum value was 24.67 MPa increasing by 363% compared to the adhesive joints without surface treatment. The mechanical interlocking between the adhesive and laser textured morphology was discovered in the fracture surface demonstrating the improvement of shear strength. [ABSTRACT FROM AUTHOR]

• A two-step approach is designed to grow crack-free CuO NWs on copper substrate. • Laser texturing increases the contact area for Cu and thermally activated O. • Tape test and ultrasonic test are used to evaluate adhesion levels of CuO NWs. CuO nanowires (NWs) are easily grown by thermal oxidation, but the practical applications have been restricted due to the cracking of CuO NWs films or exfoliation from the copper substrate. In this paper, laser texturing combined with thermal oxidation to synthesize CuO NWs demonstrates that the two-step approach is beneficial to the growth and adhesion enhancement of CuO NWs on the copper substrate. Laser texturing at different laser scan times and scan spacing forms micro-patterned grids on the copper sheet, followed by the thermal oxidation growth of CuO NWs on the laser textured copper sheet. The adhesion of CuO NWs on the copper substrate is evaluated by tape test and ultrasound test. The cross-sectional SEM images of the CuO NWs sample and the element concentrations at different layers indicate that the growth mechanism of CuO NWs conforms to the stress-driven grain-boundary diffusion model. The analysis shows that the formed micro-patterned grids by laser texturing provide additional contact area for copper and thermally activated oxygen. In addition, it contributes to thermal stress release at the edges of micro-grids, which is capable to protect the oxide layer from exfoliation. Therefore, the proposed approach has proved to be effective to adhesion enhancement of CuO NWs on the copper substrate, which is of great significance for promoting and extending the potential applications of CuO NWs in various functional surfaces and devices. [ABSTRACT FROM AUTHOR]