Effect Of Laser Parameters Research Articles

Effect of Laser Parameters on Melting Behavior of Powders in Off-Axis Laser Cladding Process

Effect of Laser Parameters on Melting Behavior of Powders in Off-Axis Laser Cladding Process

A study of bionics micro-textures on the surface of HA bio-coatings prepared by nanosecond laser

The material and surface morphology of bone implants can influence cellular activity and proliferation properties. The preparation of biomimetic microtextures on the hydroxyapatite (HA) bio-coated surface can enhance the biological properties of the implant. In this study, a nanosecond laser was used to prepare microtextures on the surface of HA coatings, and the effect of laser parameters on the ablation morphology was investigated by micromorphological observation and response surface methods. The ablation morphology was found to be better when the laser repetition frequency was 20 kHZ, the scanning speed was 300 mm/s and the number of scans was 7. Microtextures imitating fish scales and crocodile skin of different sizes were prepared on the surface of HA coatings using this laser parameter. The biological properties of the microtextures were investigated using CCK-8 tests and cell adhesion tests and the nanosecond laser-prepared mimetic microtextures were found to promote cell proliferation. A 0.1 mm radius of the mock fish scale microtexture had optimal cellular activity, where the tentacles of the cells could fully extend to the surface of the microstructure, which facilitated cell adhesion and proliferation.

The effect of laser parameters on the angular cleaning of aluminum 4004 alloy

The removal of the oxidation layer is done by altering the angle of incidence using microsecond fiber laser. A significant increase in cleaning efficiency in terms of angles and power has been noted when angular laser cleaning is used, as has been discovered in this study. Furthermore, at incident angular laser cleaning, the oxidation layer is severely degraded, decreased, and ultimately destroyed compared with perpendicular laser cleaning. The mechanism of the procedure is explored in detail by considering the laser with different powers (3, 5, 7, 10) W and incident angles (5, 10, 15, 20, 25, 30) ° and hatch distance of 0.001 mm.

Formation, evolution and characterization of nanoporous structures on the Ti6Al4V surface induced by nanosecond pulse laser irradiation

Manipulating materials at nanoscale is challenging but rewarding. Nanostructures exhibit some unique properties distinguished from macroscopic bulk materials, so fabrication of nanostructures on the material surface is beneficial to broaden their functional applications. In this study, by nanosecond pulse laser irradiation in nitrogen atmosphere, it was found that unique nanoporous structures could be formed on the Ti6Al4V surface. The effects of laser parameters including the laser power, overlap rate, scanning speed, and repetition frequency on the formation and evolution of the nanoporous structures were systematically investigated. By changing the laser parameters, the nanoporous structures with various porosities could be easily achieved on the Ti6Al4V surface. According to the structural evolution and chemical composition, the formation mechanism of the nanoporous structures was discussed. Furthermore, by characterizing the micro-mechanical properties and wettability, it was found that the surface with nanoporous structures exhibited similar surface hardness but improved tribological performances compared to the original Ti6Al4V surface, and the surface wettability could be tuned. This study provides a simple method for fabricating nanoporous structures on the Ti6Al4V surface, which would broaden its functional applications.

Wettability and frictional properties on zirconia surfaces irradiated by femtosecond laser

This study aimed to explore the wettability and tribological performance of zirconia surface by laser irradiating. To investigate the effect of laser parameters, zirconia samples were divided into two groups according to laser power and scanning pitch. The surfaces were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and goniometer. Microcracks were observed from SEM in the laser-irradiated area. The XRD results in turn indicated that the tetragonal → monoclinic (t→m) phase transformation led to microcracks formation. The contact angles (CAs) results demonstrated that the effect of laser powers on wettability was more than that of scanning pitch. With moderate laser power, it is possible to induce micro/nano morphology with best wettability. Hardness tests and friction tests were further performed to investigate the effect of laser irradiation on mechanical properties. The results indicated that the hardness of laser-irradiated showed a slightly increase, expect for the case of the percentage of m phase exceed 50 %. Meanwhile, laser irradiation can slightly reduce the coefficient of friction (COF) of dry friction and increase the COF of wet friction. For wet friction, laser-irradiated microstructure can effectively enhance the adhesion of bone to zirconia. This work may offer a simple method to produce surfaces with controlled wettability and phase transformation by selecting appropriate laser parameters to promote the adhesion of bone to zirconia.

Modelling of Pulsed Laser Ablation in Liquid via Monte Carlo techniques: The effect of laser parameters and liquid medium on the electron cloud

Pulsed Laser Ablation in Liquid (PLAL) is a method for nanoparticle synthesis in which electron clouds are involved in the ablation process by providing electron heating which increases ablation efficiency. To better understand and control PLAL, this process was modelled herein via the Monte Carlo technique and the pure jump algorithm approach. From this model, it was shown that picosecond lasers produce fewer electrons with lower kinetic energy density than femtosecond lasers within a typical material processing period that contains many pulses. It was found that photon energies of 100 eV resulted in a primary electron: secondary electron ratio of about 1 : 1.6 regardless of the number of simulated primary electrons. The maximum energy of the electron cloud during a 20 fs laser pulse with 100 eV photons was 0.05 keV regardless of the boundary condition (number of primary electrons). An increase in photon energy from 100 eV to 200 eV caused an increase of over 600% in electron cloud energy. Such an increase would be expected to have an influence on various materials processing applications. Repetition rates of 10–100 kHz were found to have no influence on the electron cloud dynamics originating from the related differences in temporal sequences.

Tuning the Surface Characteristics and Mechanical Properties of Y2O3 Coatings on a Graphene Matrix via Laser Micro Melting.

The effects of laser parameters on the microstructure and properties of plasma-sprayed yttrium oxide coating on the graphite matrix were investigated. Tensile strength, porosity, roughness, and scratch meter tests were carried out to evaluate the critical load and mechanical properties of the coating after spraying and laser micro-melting. When the porosity and surface roughness of the coating are minimum, the critical load of the coating is 7.85 N higher than that of the spraying surface. After laser micromelting, the crystal phase of Y2O3 coating surface does not change, the crystallinity is improved, and fine grain strengthening occurs. When the laser power density is 75 W/mm2, the scanning speed is 30 mm/s, and the defocusing distance is 40 mm, the film base bonding performance and wear resistance of the material reach the maximum value. The failure of Y2O3 coating is mainly due to the degradation of mechanical properties such as film base bonding strength, surface porosity, and surface roughness, which leads to the local collapse of the material. The coating after laser micro-melting only presents particle disintegration at the end of the scratch area.

Laser micro-texture formation mechanism based on modified heat-mass transfers and hydrodynamic models

Laser surface texturing is considered as a novelty and feasible technology to fabricate some micro-feature due to the non-contact, high precision and processing efficiency. However, it is difficult to deeply understand the material removal mechanism and predict the surface topography due to a confined heat-affected zone and extremely short time in the laser machining process. In this research, based on the mixed phase theory and level-set method, a modified heat-mass transfer and hydrodynamic model was proposed for deeply analyzing the influence of various physical factors such as recoil pressure, buoyancy, surface tension, gravity and thermal-mass transport on the material removal and micro-texture topography evolution at a mesoscale level. The analysis of hydrodynamic behaviors and temperature fields of the molten pool indicated that the melts sputtering and molten pool expansion caused by the recoil pressure was the dominant factor responsible for micro-texture formation during laser action. The reflux induced by the surface tension and gravity as well as the residual effect of the melts flowing upward were the main factors of the occurrence of a vortex during the molten pool cooling. Finally, the effects of laser parameters on the micro-feature topography were discussed based on the experiments and simulation model. The diameter and depth of the hole as well as the width and depth of the groove gradually increased with increasing frequency and pulse duration. The laser moving speed had less effect on the width of the groove, but it had great effect on the surface roughness of the groove. This work can be beneficial to understand the material removal mechanism and provide a guide for the parameters optimization of laser processing at a mesoscale level.

Investigation on laser forming of open cell aluminum foam

Open cell aluminum foam having high porosity has the potential to increase the efficiency of a heat exchanger and also to be used for diverse other functions. However, being prone to fail easily under tensile mechanical load, their thermal forming using a laser has been proposed in the literature. This work investigates the effect of laser parameters, orientation-position-curvature of scan path, the number of scans, and foam thickness on the bending angle achieved while forming 95% porous pure aluminum (99.7% aluminum) open cell foam plates using a diode laser. Furthermore, the capability of laser forming to produce developable and nondevelopable surfaces out of this foam has been demonstrated. Higher line energy gave a higher bending angle. Under the same line energy, the combination of higher power-higher scan speed produced a higher bending angle. In contradiction to laser forming of the sheet metal, no saturation or reduction in bending angle per scan pass was observed with an increase in scan pass number. This observation could be explained with the help of cell densification by previous scan passes leading to an increase in the coupling of more thermal energy for subsequent scan passes. Scan paths with increased curvature (or less radius) also produced higher bending due to a higher amount of cell collapse in the irradiated region.

Study on surface properties of nanosecond laser textured plasma nitrided titanium alloy

To optimize the surface properties of biotitanium alloy, a nitride layer was prepared on its surface by plasma nitriding process, and then a nanosecond laser was used to prepare microtextures on the surface of plasma nitrided (PN) titanium alloy to optimize its surface wetting properties and biocompatibility. The three-dimensional morphology of laser ablation grooves was observed, and the effects of laser parameters on the width and depth of the ablation grooves. The ablation regulation was investigated to select the optimal parameters for the preparation of microtextures (stripes and grids). It was found that the material removal rate was positively correlated with the laser pulse overlap rate, and the laser overlap rate decreased with the increasing of ablation speed and increased with the increasing of laser repetition frequency. Diffraction peaks of Ti-N-O non-integrable compounds appeared on the ablated surface of microtextured samples. The regular ablation textures appeared on the surface of textured samples, and granular melt products appeared at the edges of the textures. The wettability of microtextured samples was improved, which was beneficial to improve the biocompatibility of PN titanium alloy. Due to the overlapping of scan paths, the ablation morphology of textured samples with scan spacing smaller than the spot diameter was irregular and the depth of ablative groove was smaller, which has better wettability. The electrochemical corrosion tests showed that the corrosion resistance of the samples with 0.05 mm scanning spacing was better than that of the samples with 0.02 mm scanning spacing. In addition, after 30 days of immersion corrosion, only a few corrosion products appeared on the surface of all the textured samples, and no corrosion cracks and holes appeared, so the laser textured PN titanium alloy has better corrosion resistance.

Formation of laser-induced periodic surface structures on amorphous Fe- and Co-based alloys and its impact on magnetic properties

Laser-induced periodic surface structures, so-called LIPSS, were obtained using linearly polarized femtosecond laser pulses on metal glasses with compositions Fe73.5Nb3Cu1Si15.5B7 and Co73Fe1Mn3Mo1Si13B9. The effect of laser parameters on spatial period and regularity of LIPSS was observed. Highly regular and low spatial frequency LIPSS with a period in the range of 850–950 nm was revealed using FESEM studies. The backscattered X-ray diffraction method revealed no devitrification of the amorphous structure upon LIPSS forming. Magnetic properties including saturation magnetization, coercive force, thermomagnetic curves were measured for both materials before and after LIPSS generation. It was observed that LIPSS impacts the coercive force of the amorphous Fe- and Co-based alloys.

The effects of simultaneous laser nitriding and texturing on surface hardness and tribological properties of Ti6Al4V

The low hardness and poor tribological properties of titanium and its alloys significantly hinder their practical engineering applications, so surface nitriding or texturing is widely employed to improve the surface performances. However, previous studies mainly used the single method (surface nitriding or texturing), and simultaneous nitriding and texturing are rarely reported. Therefore, their combined effects on the surface mechanical and tribological properties are rarely investigated as well. In this study, by nanosecond pulse laser irradiation in nitrogen atmosphere, simultaneous nitriding and texturing of the Ti6Al4V surface were achieved. The effects of laser parameters including laser power, laser overlap rate, and number of scanning cycles, on the surface hardness and tribological properties of laser irradiated surfaces were comparatively studied. The experimental results showed that after simultaneous laser nitriding and texturing, the surface hardness of Ti6Al4V surface was increased by 50%~95%, and the coefficient of friction (COF) was reduced by 70%~80%. Furthermore, the laser processed surfaces obtained under various irradiation parameters presented quite different scratching characteristics, and the corresponding deformation mechanisms during scratching were analyzed. This study provides a simple and effective method by simultaneous laser nitriding and texturing for improving the surface properties of Ti6Al4V, which would be meaningful for its practical engineering applications.

Effect of Laser Parameters on Laser-Induced Graphene Filter Fabrication and its Performance for Desalination and Water Purification

Effect of Laser Parameters on Laser-Induced Graphene Filter Fabrication and its Performance for Desalination and Water Purification

Modelling of Pulsed Laser Ablation in Liquid Via Monte Carlo Techniques: The Effect of Laser Parameters and Liquid Medium on the Electron Cloud

Modelling of Pulsed Laser Ablation in Liquid Via Monte Carlo Techniques: The Effect of Laser Parameters and Liquid Medium on the Electron Cloud

Effect of laser ignition on combustion and performance of internal combustion engine: A Review

• Laser ignition system as a prominent alternative to spark plug ignition has been reviewed. • Laser ignition is superior in context of ignition, combustion, and emission characteristics. • Effect of laser parameters on the performance of internal combustion engines have been studied. • Feasibility of laser ignition with respect to varying ignition location and possibility of multipoint combustion initiation has been reviewed. Internal combustion engines have undergone many technological advancements over the period keeping in mind economic aspects and stringent emission norms in context of global environment changes. Research in this field mainly emphasizes performance enhancement. Improved performance can be in terms of efficiency improvement, emission reduction or higher power output keeping inputs variables unchanged. The key process that can affect all mentioned perspectives is combustion. The ignition system initiates the combustion process and ensures that it happens in an organized manner as per expectations. Laser ignition systems have numerous benefits over spark ignition systems like superior lean burn capacity, excellent control over ignition timings, flexible ignition locations and improved performance and emission characteristics. Majority of studies have used Q-switched Nd: YAG lasers for their research. Laser ignition system comprises different attributes like minimum ignition energy (MIE), wavelength, pulse duration and focal length of lens and focal spot size which has a vital influence on engine combustion characteristics. The purpose of this article is to examine the scope and current level of research towards implementing laser ignition systems in real-world automobiles. Compactness, cost, and misalignment of the laser system due to real-time vibration of engines are a few of the major hurdles. Further research into these important issues, together with the improved benefits of laser ignition, could result in a significant contribution in the automobile sector, with the goal of commercialization.

Nanosecond laser-induced controllable oxidation of TiB2–TiC ceramic composites for subsequent micro milling

Laser-induced controllable oxidation coupled with micro-milling (LOMM) provides a feasible way to machine difficult-to-machine materials such as TiB 2 –TiC ceramic composites. The oxidation mechanism of the material under laser irradiation represents the fundamental issue of LOMM. In this paper, laser-induced controllable oxidation of spark plasma sintered TiB 2 –TiC ceramic composites as the workpiece material was studied. A three-dimensional finite element model was established based on ABAQUS/CAE 6.14 software to simulate the effect of laser parameters on temperature field distribution and was verified by experiments. The influence of laser processing parameters and assisted gas atmospheres on the oxidation behavior of TiB 2 –TiC ceramic composites was investigated. Results revealed that the irradiated temperature which had a significant impact on oxidation behavior, increased with an increment of the laser fluence and decreased with an increment of scanning speed with other laser parameters fixed. In addition, based on experimental analysis, the thickness of the oxide-layer increased with an increase of laser fluence and reduced with increasing laser scanning speed. At a laser fluence of 10.78J/cm 2 and scanning speed of 1 mm/s as well as in an oxygen-rich atmosphere, a loose and porous oxide-layer was produced on the irradiated surface. Cross-section thicknesses of the oxide-layer and sub-layer reached 63 μm and 22 μm, respectively. Moreover, the thickness of the oxide-layer was 22 μm in air surroundings and hardly be found in argon and nitrogen atmospheres under identical laser parameters, which indicated that oxygen content had a significant influence on the oxidation reaction of the material. The products of the oxide-layer were mainly composed of rutile- and anatase-TiO 2 . Furthermore, the hardness of the sub-layer was 9.6 ± 0.7 GPa at a laser fluence of 10.78J/cm 2 and scanning speed of 1 mm/s, which was far lower than that of the substrate with a hardness of 20 ± 0.7 GPa. This study provides a theoretical basis for subsequent micro-milling.

Evaluating the Effect of Laser Parameters on the Cutting Performance of Textured Cutting Inserts in the Machining of Ph 13-8 Mo Stainless Steel (Ss)

Evaluating the Effect of Laser Parameters on the Cutting Performance of Textured Cutting Inserts in the Machining of Ph 13-8 Mo Stainless Steel (Ss)

Gain-switched short pulse generation from InAs-InP (1 1 3)B quantum dot laser excited state

The gain switching characteristics and the effect of laser parameters on the output pulses of an InAs-InP (113)B quantum dot laser are investigated for the first time using theoretical models to obtain shorter pulses by applying an external optical beam to the laser excited state. The model is based on the rate equations, which are solved by the Runge –Kutta method. The results showed that without an optical beam, long pulse widths are obtained because of the ground state transition, and the change in the parameters strongly affects the laser output. However, with an optical beam illumination, short pulses with a width of 25–40 ps with a high peak power are generated owing to the excited state transition at low currents, and the change in the laser parameters does not affect the output pulses strongly. These results are important for long-distance optical transmissions as well as medical biotechnology.

Preparation of superhydrophobic glass surface with high adhesion

This paper prepared the superhydrophobic surfaces on the glass substrate by the ablation of grid microstructures using picosecond laser and subsequence chemical modifications by silanization. The novelties in this research are the superhydrophobic surfaces prepared with high adhesion and further exploration of the effect of abrasion on its superhydrophobic and adhesion properties. The surface morphologies were characterized by a scanning electron microscope (SEM) to reveal the effect of laser parameters on micro-nano structure. The water contact angles and surface roughness values were measured to illustrate the effect laser parameters on surface wettability. The surface energy was calculated to prove the correlation between lower surface energy and superhydrophobicity. The chemical composition of the surfaces was detected by an X-ray photoelectron spectroscopy (XPS) to explore the mechanism of changes in wettability from the reaction of fluorosilane and glass materials perspectives. The surface adhesion experiments were also performed to reveal the relationship between surface adhesion and laser parameters. The results indicated that the micro/nano structure by laser-induced were substantially dependent on the laser energy and significantly affected the adhesion. However, the number of scans slightly affected the surface morphologies and the adhesion. Finally, the abrasion resistance experiments were conducted to observe the relationship between abrasion cycle to contact angle and adhesion.

Design and micromachining of a stretchable two-dimensional ultrasonic array

Focused ultrasound using stretchable ultrasonic arrays is a very attractive method for ultrasound neuromodulation. However, the structure and fabrication of the arrays have brought great challenges for the development of stretchable ultrasonic arrays. In this work, an improved 6 × 6 stretchable two-dimensional ultrasonic array has been proposed based on laser micromachining technology. The structure and shape of the serpentine hinge are optimized to avoid delamination between layers and to reduce the stress concentration during the stretching process. Due to the thorough studies over the effects of laser parameters on the kerf profile, clean and accurate serpentine hinge shapes can be obtained conveniently. Array elements are connected using serpentine hinges to form a stretchable two-dimensional structure. Thus, a reliable electrical connection and stable array structure are formed, which can provide 100% yield and excellent mechanical stretchability. Based on the three-dimensional scanning guidance, simulation results of ultrasonic spatial focusing on a complex surface demonstrate that our device has promising applications for ultrasound neuromodulation. • An improved 6 × 6 stretchable two-dimensional ultrasonic array with row and column electrodes. • Optimized serpentine hinge reducing the maximum stress during array stretching. • Laser micromachining serpentine hinge with clean and accurate profile. • Spatial focusing of the stretchable ultrasonic array based on three-dimensional fast scanning.