Hybrid Laser Processing Research Articles

Enhanced fatigue life of additively manufactured high-strength TiB2-reinforced Al-Cu-Mg-Ag composite through in-process surface modification during hybrid laser processing

ABSTRACT Laser powder bed fusion (L-PBF), an additive manufacturing (AM) technique, often leads to parts with high surface roughness in as-built condition, hence limited fatigue performance. This paper showcases the favourable impact of applying an in-process surface modification, adopting a hybrid laser processing technique (dual-laser PBF (dL-PBF)), on the three-point bending fatigue life of TiB2-reinforced Al-Cu-Mg-Ag composite coupons. The dL-PBF process parameters are optimised for this high-strength aluminium-based metal matrix composite, followed by a comparative study between 3 surface conditions, i.e. as-built, dL-PBF processed, and milled, focusing on surface roughness, concomitant stress concentration factor, surface residual stress, sub-surface hardness, sub-surface microstructure, and fatigue performance. While no significant hardness or microstructural differences are found, surface roughness and stress concentration factor are substantially decreased (> 50%) and identified as the primary factors for the significantly enhanced fatigue performance of dL-PBF processed TiB2-reinforced Al-Cu-Mg-Ag composite parts with up-facing inclined surfaces.

NIR-UV Dual-Mode Photodetector with the Assistance of Machine-Learning Fabricated by Hybrid Laser Processing

Photodetectors are widely used in optoelectronic applications such as remote controlling, optical communication, and intelligent manufacturing. Multi-wavelength response capability can expand the application scenarios of a photodetector. However, responding to and recognizing multiple bands is still challenging for a photodetector. Here, we develop a dual-mode photodetector that can respond to and recognize near-infrared (NIR) and ultraviolet (UV) light with the assistance of a machine-learning model. A hybrid laser processing method was proposed to fabricate this photodetector based on the polyimide substrate. This method uses femtosecond laser and continuous wave laser to induce the formation of carbon and zinc oxide composite material in different forms. The femtosecond laser-processed area and the continuous wave laser-processed area realized stable NIR light detection and UV light detection, respectively. Recognition of the type of incident light was realized with the assistance of a machine-learning classification model. The proposed hybrid laser processing method combines the characteristics of two kinds of lasers and provides new insights into fabricating dual-mode photodetector. This photodetector could advance the development of dual-mode photodetection and has application potential in many fields like wearable devices and smart clothing.

Ultraminiaturized Microfluidic Electrochemical Surface‐Enhanced Raman Scattering Chip for Analysis of Neurotransmitters Fabricated by Ship‐in‐a‐Bottle Integration

Electrochemical surface‐enhanced Raman scattering (EC‐SERS) is a promising technique for the diagnosis of trace amounts of neurotransmitters, because it can elucidate neurotransmitters’ behavior on electrodes to deduce their functions in the human body. However, the current EC‐SERS devices need several tens of milliliters of analyte solution to collect enough signal for analysis. Miniaturization of EC‐SERS devices is crucial for the early diagnosis of disease and point‐of‐care testing. Herein, a new type of EC‐SERS sensor based on 3D microfluidic chips for the analysis of neurotransmitters in ultrasmall volumes is proposed. The microfluidic EC‐SERS chip is fabricated by a ship‐in‐a‐bottle technique based on hybrid laser processing. The working electrode is modified using silver/zinc oxide materials, enabling the formation of a unique “candy apple” structure. To assess the fabricated microfluidic EC‐SERS chips, ascorbic acid is analyzed using the ingenious microfluidic EC‐SERS chips to elucidate its redox reaction by EC‐SERS spectroscopy. Significantly, a sub‐10 μL volume of analyte solution is sufficient for EC‐SERS analysis, which is several orders smaller in volume than the requirements of current EC‐SERS devices. The unprecedented microfluidic EC‐SERS chips fabricated by the ship‐in‐a‐bottle integration technique can be used in portable and smart analyzers for next‐generation biomedicines and catalysts.

Study of the dynamics of material removal processes in combined pulse laser drilling of alumina ceramic

Combined pulse laser (CPL), one of the hybrid laser processing technologies, has proven to be a reliable tool for the high-quality and high-efficiency material processing. In CPL drilling, the nanosecond laser has been proven that it can improve the drilling performance of the millisecond laser by increasing the laser absorption or improving the sputtering of the melt. However, the dynamics of material removal processes regarding CPL drilling have not been systematically investigated. In this paper, a numerical model of the CPL drilling of alumina ceramic was built to reveal the dynamic processes of the energy absorption, phase transformation, and micro-hole deformation process. The millisecond laser absorption enhanced by the ablated keyhole was quantified and considered as saturation (100 %), thus improving the drilling efficiency. In addition, the shock wave generated by the nanosecond laser accelerated the removal of the melt with a sputtering velocity of up to 23.8 mm/ms, which was much higher than the recoil pressure generated by the saturation vapor pressure, ensuring the drilling quality. Also, the experimental results showed that well drilling quality (1.09° taper angle, 0.96 circularity) were obtained for 1 mm thick alumina ceramic with a material removal rate as high as 1.9 × 104 μm3/μJ. The analysis and summary of the CPL drilling mechanism helps to further improve the drilling performance and provide a new technological route for high-speed processing of ceramic substrates.

Development and investigations on a hybrid tooling concept for coaxial and concurrent application of electrochemical and laser micromachining processes

In hybrid laser-electrochemical micromachining, both laser and electrochemical process energies act along the same machining axis and thus both influence material removal by their interaction. The traditional nozzle based laser assisted jet-ECM concepts require laser to be focused on workpiece surface in an electrochemical environment and are limited in aspect ratios as the nozzle stays above the workpiece surface. In this work, a hybrid tooling concept is proposed for a novel process scheme of precision hybrid laser-electrochemical micromachining. The tool serves the function of both an ECM electrode as well as a leaky-type multimode waveguide for the laser and delivers laser homogeneously together with the electrolyte on the workpiece surface without requiring laser to be focused on the workpiece surface. A precision prototype hybrid machine-tool is developed which employs short pulsed nano-second laser and micro-second pulsed voltage source for precision micromachining. For this system, ray tracing and detailed multiphysics electrochemical micromachining process simulations are carried out to demonstrate the applicability of this hybrid tooling concept and explain the shape evolution. Successful experimental realization of coaxial and concurrent application of electrochemical and laser processes is presented. Prototype tool electrodes are fabricated and experiments are carried out on an in-house developed prototype hybrid machine tool. The results reveal that the proposed hybrid tool is successfully capable of concentrating laser and electrochemical process energies simultaneously in the same machining zone. However, with the initial design of this hybrid tool, a maximum of 30–40% of laser power is available in the machining zone. Some suggestions for further research will be presented.

Aunps and Agμps-functionalized zirconia surfaces by hybrid laser technology for dental implants

This work presents innovative zirconia surfaces functionalized with gold nanoparticles (Aunps) and silver microparticles (Agμps) through versatile laser technology where laser parameters and subtractive/additive strategies were combined to apply in dental implant surfaces regarding antibacterial potentialities. Aunps-functionalized zirconia surfaces were produced by a hybrid process starting with nanoparticles production by Nd:YAG laser ablation, followed by its deposition through spray system and its adhesion to the zirconia surface by the laser CO2 action, varying laser power and scan speed parameters. Agμps-functionalized zirconia surfaces were obtained through a hybrid laser process starting by laser texturing of the compacted zirconia surface, followed by allocation of Ag powder into the texture and its subsequent laser sintering, varying laser power. The functionalized zirconia surfaces were analyzed through SEM/EDS. In order to mimic the implant screwing effect, the samples were subjected to reciprocating friction tests against bone. It allows to evaluate the adhesion of the zirconia surface to the bone and the resistance to surface detachment. A purple colloidal solution of spherical gold nanoparticles with an average size of 5 ± 3 nm was successfully produced by laser. The friction tests revealed a good behavior of both functionalized zirconia surfaces indicating that their integrity is not affected during implant screwing insertion. A good dispersion of nanoparticles on the zirconia surface was observed indicating that the spray system is an effective way to deposit nanoparticles on the surface. A high amount of agglomerates was found for samples where low laser power (P = 11W) and scan speed (v = 1000 mm/s) were applied, probably due to the high density of energy (E). A decrease of defects on the sintered Ag layer with increasing laser power from 3 to 6 W was found, mainly related with the amount of laser energy density. The ion release showed to be strongly dependent on particle size.

Experimental investigation on a new hybrid laser process for surface structuring by vapor pressure on Ti6Al4V

Besides conventional structuring processes such as turning, milling or photo-chemical etching, laser processes are increasingly being used for surface structuring of metals. These laser processes differ fundamentally in that structuring is carried out either by material removal or by material redistribution. In this study, a new hybrid process of material ablation by means of pulsed laser radiation and material redistribution based on a remelting process by means of cw laser radiation is experimentally investigated. Besides an introduction to this new hybrid process, we give a detailed description of the equipment and methods used as well as surface structures produced on Ti6Al4V. A melt pool was generated on a prepared Ti6Al4V surface using cw laser radiation with a laser beam diameter of 520 μm, laser power of 220 W, and a scanning velocity of 100 mm/s. In order to create surface structures, simultaneously, superimposed pulsed laser radiation with a laser beam diameter of 65 μm, pulse duration of 60 ns, a maximum pulse energy of 0.35 mJ, and a pulse frequency of 50 kHz was used to evaporate small amounts of molten material from the melt pool. This localized evaporation of molten material is assumed to create vapor pressure that deforms the melt pool surface and therefore leads to surface structures. Our results indicate that by pulsed laser radiation capillary surface waves with a wavelength of the doubled laser beam diameter are excited on the melt pool surface. This forced excitation of capillary surface waves result in surface structures that are analyzed after solidification by means of white light interferometry. Based on this analysis we derived an oscillation frequency of ν = 2.27 (± 0.16) kHz for the excited capillary surface wave as well as an effective kinematic viscosity of μ = 0.1328 cm2 s−1 for the damping of this surface oscillation during solidification. In terms of structural features, we achieved surface structures with heights of up to 100 μm. Furthermore, structure height controllably scales in dependence on pulse energy and number of laser pulses as long as no ejection of molten material takes place. Finally, a comparison of the redistributed material volume per time shows that we achieved a volume redistribution rate of 28.37 mm3/min, which is significantly bigger than has been achieved with other laser texturing techniques so far and demonstrates the high potential of this new hybrid technique not only for surface structuring purposes.

Hybrid laser and vacuum process for rapid ultrahydrophobic Ti-6Al-4 V surface formation

A novel technique of post-vacuum processing the laser patterned surface was used for high speed fabrication of Ultrahydrophobic Ti6Al4V surface and the basics behind the transformation of surface chemistry is investigated in this paper. The wetting property of the laser patterned dual geometry structures transforms to ultrahydrophobic in 120 min of vacuum process without any chemical treatments to suppress the surface polarity. The surface recorded static contact angle of 180°, sliding angle less than 5, and exhibits bouncing and roll-off characteristic due to the presence of composite interface. The transformation of hydrophobic property establish a clear relationship between the vacuum process period and the improvement in static contact angle. The surface chemical analyses by XPS reveals that the amount of surface carbon content increases 2.3 times higher because of the adsorption of unstable organic molecules by vacuum process. The low partial pressure of the water molecules (120 min.) compared to those occurs at standard atmospheric pressure (days). The transformation of freshly laser processed Ti6Al4V hydrophilic surfaces into ultrahydrophobic surface is due to the development of carbonaceous layer over the laser patterned structures, which helps to sustain the Cassi-Baxter state.

HAp-functionalized zirconia surfaces via hybrid laser process for dental applications

The development of new approaches to improve the implant integration and subsequently its long-term maintenance is an actual challenge. In this way and trying to mimic natural bone composition, HAp-functionalized zirconia surfaces were produced by means of hybrid laser technique combining additive (laser sintering) and subtractive (laser machining) processes. Nd:YAG laser-generated textures were created to improve mechanical interlocking of hydroxyapatite (HAp) powder and consequently enhance its adhesion to zirconia surface. Different laser parameters and also different approaches were tested to optimize the textured line-patterning of zirconia surface. The created microtextures were characterized by Scanning Electron Microscopy (SEM). Furthermore, textured zirconia surfaces were functionalized with HAp by means of CO2 laser. Different power and scan speed laser parameters were tested to promote HAp retention inside of line-patterning. The results showed that it is possible to design the textured surface by changing energy density and atmosphere. Furthermore, high amount of retained and sintered bioactive material was found when high laser power and low scan speed were performed.

Математическая модель эффективности использования лазерного излучения при гибридной обработке

Математическая модель эффективности использования лазерного излучения при гибридной обработке

Composite Polymer Joining by Laser Combined Hybrid Laser Process

A novel hybrid process (2D scanner + LASER + CNC machining) was used to join transparent and opaque polymers. A 30W diode laser and a 3-axis CNC machining center were combined to accommodate a 2D scanning system for high flexibility and productivity. The scanning speed, the number of repetitions and the laser power were selected as parameters for the weld test. By combining CNC and laser, the productivity and accuracy were improved and manufacturing cost decreased accordingly. The maximum speed of 1130 mm/min was achieved with minimum power of 2Watt. The developed system demonstrated the joining of transparent PC and opaque ABS polymers by using 2 dimensional laser beam motion. The air gap could be minimized by using constant force on the upper holding plate, and preheating by the first run of the laser system. The weld bead decreased at the lower laser power and the higher laser scanning speed.

Effect of Water-jet on Laser Paint Removal Behaviour

The laser paint removal behaviour with water-jet assist laser has been investigated using Yb- fiber laser. The conventional laser paint removal process with gas-jet assist usually leaves behind traces of combustion product i.e. ashes on the surface. An additional post-processing such as light-brushing or wiping by some mechanical means is required to remove the residual ash. In order to strip out the paint completely from the surface in a single step, a hybrid laser process which utilizes a water-jet along with laser beam has been developed. A coaxial water-jet along with a high power fiber laser beam removed the paint and residual ashes very effectively. The specific energy, defined as the laser energy required removing a unit volume of paint was found to be marginally higher than that for the gas-jet assisted laser paint removal process. However, complete paint removal was achieved with the water-jet assist only.

Fabrication of nanoporous metal by selective electrochemical dealloying from laser cladding Cu-Mn alloys

The nanoporous metal is fabricated by means of hybrid laser processing in combination with electrochemical dealloying. Cu-Mn alloy coatings with fine shape, low dilute ratio and refined microstructure are fabricated on medium carbon steel by means of laser processing. Polarization curve indicates that the Cu-Mn alloy shows selective dissolution characteristics for different electrolytes. Nanoporous Cu and nanoporous Mn are fabricated with optimal electrochemically dealloying parameters. Nanoporous Cu has pore sizes rangeing from 30 to 50 nm, while the surface morphology of the porous Mn shows a ribbon-like structure with ultrahigh roughness factor up to 900. Finally, the potential-pH diagram is used to explain the mechanism of the dealloying.

Photodegradation of Methyl Orange under Visible Light by Micro-Nano Hierarchical Cu2O Structure Fabricated by Hybrid Laser Processing and Chemical Dealloying

Micro-nano hierarchical structure on the substrate was fabricated by a hybrid approach including laser deposition, laser ablation and chemical dealloying. The structure consists of micro bumps with a width of 50 μm and a height of 100 μm, and nanoporous structures with a size of 70-150 nm on the micro bumps. XRD and XPS results confirm that these hierarchical structures were made of Cu(2)O. For use in comparison, three additional structures with feature size in milliscale, microscale, and nanoscale were also prepared respectively by the proposed methods. Under visible light, the micro-nano structure exhibited the best performance of photodegradation. It is the result of the large specific surface and the catalytic reaction driven by the cuprous oxides.

Laser-induced Writing of Submicron Surface Relief Gratings in Fused Silica on the Fly

The hybrid laser processing method LIBWE (laser-induced backside wet etching) allows the defined micro and submicron structuring of transparent materials like fused silica at small laser fluences and with high quality. In this study the etching of fused silica with mercury as liquid absorber is demonstrated using an excimer laser (λ = 248 nm, 25 ns pulses). The high absorption coefficient of liquid metals enlarges the absorption of the UV laser radiation so that despite the high reflectivity the threshold for etching was measured to be 0.75 J/cm2. With rising laser fluence the etch rate linearly increases in the whole laser fluence range and reaches a value of 650 nm/pulse at a laser fluence of about 10 J/cm2. For the etching of 2D periodic sub-micron structures into fused silica, four interfering laser beams were used generated by projection of a chessboard-like diffraction phase mask. In conjunction with liquid-metal LIBWE, submicron surface relief gratings with regular dot patterns have been realized on planar and prestructured samples in a one-step direct fabrication process. The large etch rates at LIBWE by means of the liquid metal enable a highspeed processing; gratings with a period of 800 nm and a depth up to 60 nm can be etched on the fly with only one laser pulse.

Hybrid laser processing for microfabrication of glass

Hybrid laser processing for the precision microfabrication of glass materials, in which the interaction of a conventional pulsed laser beam and a medium on the material surface leads to effective ablation and modification, is reviewed. A major role of the medium is to produce strong absorption of the conventional laser beam by the material. Simultaneous irradiation by a vacuum ultraviolet (VUV) laser beam that possesses an extremely small laser fluence and an ultraviolet (UV) laser greatly improves the ablation quality and modification efficiency for fused silica (VUV-UV multiwavelength excitation process). The metal plasma generated by the laser beam effectively assists high-quality ablation of transparent materials by the same laser beam, resulting in microstructuring, cutting, color marking, printing, and selective metallization of glass materials (laser-induced plasma-assisted ablation (LIPAA)). The detailed discussion presented here includes the ablation mechanism of hybrid laser processing.

Numerical Simulation Of Welding In Shipbuilding

In the context of a fierce competition between European and Asian shipyards, quality and productivity improvement are of major importance. Continuous work has always been done on welding techniques : 0 to increase the efficiency of the traditional Arc welding technology; to master the new technology of metal joining by Laser welding; to adopt a Laser-Arc combination process (Hybrid Laser welding). In this paper, advantages and drawbacks of each process are briefly analysed. A short presentation of the PRINCIPIA methodology of numerical simulation initially developed for Arc welding process is presented and an adaptation to Laser and Hybrid Laser process is then described enabling for a new shipbuilding project to predict, control and optirnise the design andlor the welding parameters in order to avoid excessive distortions due to welding effects on thin stiffened panel assemblies in shipbuilding. Those distortions imply costly straightening work. Finally, as an example, a fine finite element model is presented modelling an assembly of three thin stiffened plates which are joined by arc welding process. The buckling state of the calculated model is then identified with the real buckled deformed shape of the arc-welded assembly in order to test the validity of the PRINCIPIA methodology.

Advanced materials processing based on interaction of laser beam and a medium

Hybrid laser processing for precision microfabrication of hard materials, in which the interaction of a conventional pulsed laser beam and a medium on the material surface leads to effective ablation and modification, is reviewed. The main role of the medium is to produce strong absorption of the nanosecond laser beam by the materials. Simultaneous irradiation with the vacuum ultraviolet (VUV) laser beam which possesses extremely small laser fluence greatly improves the ablation quality and modification efficiency for hard materials such as fused silica, crystal quartz, sapphire, GaN, and SiC by the ultraviolet (UV) laser irradiation (VUV–UV multiwavelength excitation process). Metal plasma generated by the laser beam effectively assists high-quality ablation of transparent materials, resulting in microstructuring, cutting, color marking, printing and selective metallization of glass materials (laser-induced plasma-assisted ablation (LIPAA)). The detailed discussion presented here includes the ablation mechanism of hybrid laser processing.

Applications of Laser Ablation-the Sate of the Art and Future Prospects

Present status and future prospect of the application of laser ablation phenomena are reviewed, especially focused on the application to the synthesis of functional thin films and nanostructured materials, and to the laser micro-processing using femto-second lasers, hybrid laser processing and other novel methods.

Precision Microfabrication of Hard Materials by Hybrid Laser Processing

Precision Microfabrication of Hard Materials by Hybrid Laser Processing