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In this work the influence of picosecond laser (ps) irradiation (PLI) on the properties of black Cr electrodeposited on an SS substrate has been investigated. XPS has shown that black Cr treatment by PLI changes the concentrations of elements on the black Cr coating surface. Furthermore, it diminishes the quantity of CrN compound, while increasing the quantity of metallic chromium (Cro). Full reflectance (RD) of black Cr after treatment with PLI and before treatment in the visible region (300–800 nm) were quite close. Thermal tests at a temperature of 200 oC showed that the adhesion between black Cr treated with PLI and SS is better than that of black chromium not treated with PLI. Thus, such a black Cr absorber may be used in solar water heaters. [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]

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]

The mass production of polymeric parts with functional surfaces requires economically viable manufacturing routes. Injection moulding is a very attractive option, however, wear and surface damage can be detrimental to the lifespan of replication masters. In this research, austenitic stainless steel inserts were hardened by low temperature plasma carburising and then different micro and nano scale surface textures, inspired by Lotus leaves and Springtail skins, were laser fabricated. A commonly available talc-loaded polypropylene was used to produce 5000 replicas and thus to investigate the evolution of surface textures both on inserts and replicas together with their functional response. The progressive wear or surface damage on the inserts during the injection moulding process had a clear impact on surface roughness and peak-to-peak topographies of the replicas. In general, polymer replicas produced with the carburised inserts retained wetting properties for longer periods compared with those produced with the untreated replication masters. [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]

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]

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

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

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

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

The development of implant metal-free surfaces has gained attention since non-benefic results have been reported related to the metallic ions released from metal implants to the human body. Ceramic coatings have been proposed as a possible solution however, the detachment of these coatings, during implantation or even in function, can compromise its function. In order to overcome this problem, this work proposes a novel hybrid Ti6Al4V–ZrO 2 surface, starting with laser texturing of the Ti6Al4V substrate by Laser Nd:YV04, followed by the allocation of the zirconia (ZrO 2) powder and its subsequent sintering by hot pressing process. Results revealed that zirconia strongly adheres to titanium textured surfaces since no detachment was found under tribological and adhesion scratch tests. Moreover, the tribological results showed that the incorporation of zirconia into textured titanium surface reduces significantly the wear rate of titanium (≈93%), which is a good indicator of low metallic particles/ions released to the body. These results suggest that this novel surface with good aesthetic properties and improved wear resistance (given by zirconia) and mechanical resistance (from titanium) can be a promising solution for dental implants, especially for implant/abutment or abutment/ceramic contact zones, and thus have a huge impact on the long-term performance of implants. [Display omitted] • Hybrid Ti6Al4V–ZrO 2 was successfully produced by Laser and Hot pressing techniques. • A strength adhesion was achieved between ZrO 2 and Ti6Al4V-textured substrate. • A significant reduction in the Ti6Al4V wear rate was achieved by adding ZrO 2. • A novel surface with high aesthetic properties and wear resistance was produced. [ABSTRACT FROM AUTHOR]

In the thin-film photovoltaic industry, to achieve a high light scattering in one or more of the cell interfaces is one of the strategies that allow an enhancement of light absorption inside the cell and, therefore, a better device behavior and efficiency. Although chemical etching is the standard method to texture surfaces for that scattering improvement, laser light has shown as a new way for texturizing different materials, maintaining a good control of the final topography with a unique, clean, and quite precise process. In this work AZO films with different texture parameters are fabricated. The typical parameters used to characterize them, as the root mean square roughness or the haze factor, are discussed and, for deeper understanding of the scattering mechanisms, the light behavior in the films is simulated using a finite element method code. This method gives information about the light intensity in each point of the system, allowing the precise characterization of the scattering behavior near the film surface, and it can be used as well to calculate a simulated haze factor that can be compared with experimental measurements. A discussion of the validation of the numerical code, based in a comprehensive comparison with experimental data is included. [ABSTRACT FROM AUTHOR]

The femto second pulsed laser having ultra-short pulse duration has significant advantage in creation of specific micro features on surfaces of tribo-elements for improving their performance behaviors. Machining of micro-dimples on the hardened steel (AISI 52100) flat surfaces was done for creating the point contacts with the counter ball of same material. The friction and vibration behaviors of such lubricated textured point contacts under reciprocating rolling motion are reported. At combinations of high load and rolling speed, the surface textured contacts yielded significant reduction in rolling friction and vibration amplitude (at resonance frequencies) in comparison to smooth contacts. [ABSTRACT FROM AUTHOR]

Abstract: Surface texturing is gaining interest in the field of surface engineering. Enhancements can be obtained by carefully creating textures with arrangement of 3D-cavities; such textures retain lubricant and enhancing the hydrodynamic effect, reducing therefore the friction coefficient and wear of sliding contact surfaces 3D-cavities may have flat or curved shapes. In this investigation a picosecond pulsed laser with 1030nm and 343nm has been used to develop precise surface textures with triangular and flat shaped profiles. Tribological essays showed improvements in the tribological behavior of textured surfaces, triangular profile cavities obtained a friction coefficient < 0.03 doubling the wear resistance compared to reference surface without texture. [Copyright &y& Elsevier]