Laser Processing Research Articles

Optimization of laser process parameters and improved corrosion behaviour of LZ/YSZ thermal barrier coating

Abstract Laser processing the surfaces of plasma-sprayed thermal barrier coatings is one of the methods used to improve the corrosion resistance of the coatings. However, laser glazing alone is not sufficient to fully protect coatings from corrosion. In this study, optimum laser surface modification parameters were determined for plasma-sprayed LZ/YSZ double-layer thermal barrier coatings. The coating surface, whose entire surface was scanned with optimum parameters, was modified with nano YSZ using the electrophoretic deposition technique. Thus, the network cracks formed during laser glazing were filled with nano YSZ. The coating modified by laser and electrophoretic deposition processes was subjected to corrosion tests. As a result of the characterizations, it was determined that the optimum laser surface modification parameters for LZ/YSZ thermal barrier coatings were 200 mm laser distance, 120 scan speed, and 28w laser power. With these parameters, discontinuities on the as-sprayed coating surface were eliminated. A dense layer was successfully created on the LZ layer. As a result of the corrosion tests, it was determined that modifying the laser-glazed surface with nano YSZ reduced the penetration depth of corrosive contaminants. Thus, the glassy melt and hot corrosion resistance of LZ/YSZ thermal barrier coatings was increased.

Fiber Optic Micro-Hole Salinity Sensor Based on Femtosecond Laser Processing.

This study presents a novel reflective fiber Fabry-Perot (F-P) salinity sensor. The sensor employs a femtosecond laser to fabricate an open liquid cavity, facilitating the unobstructed ingress and egress of the liquid, thereby enabling the direct involvement of the liquid in light transmission. Variations in the refractive index of the liquid induce corresponding changes in the effective refractive index of the optical path, which subsequently influences the output spectrum. The dimensions and quality of the optical fiber are meticulously regulated through a combination of femtosecond laser cutting and chemical polishing, significantly enhancing the mechanical strength and sensitivity of the sensor's overall structure. Experimental results indicate that the sensor achieves salinity sensitivity of 0.288 nm/% within a salinity range of 0% to 25%. Furthermore, the temperature sensitivity is measured at a minimal 0.015 nm/°C, allowing us to neglect temperature effects. The device is characterized by its compact size, straightforward structure, high mechanical robustness, ease of production, and excellent reproducibility. It demonstrates considerable potential for sensing applications in the domains of biomedicine and chemical engineering.

Tag paper substrate enhanced self-assembled graphene oxide-Ti3C2Tx MXene composites for supercapacitors applications via laser processing

Tag paper substrate enhanced self-assembled graphene oxide-Ti3C2Tx MXene composites for supercapacitors applications via laser processing

Nickel-oxide embedded laser-induced graphene for high-performance supercapacitors.

This study explores the fabrication of nickel-oxide-embedded laser-induced graphene and its application in high-performance supercapacitors. Supercapacitors are critical for various applications due to their high power density and long cycle life. Nevertheless, they suffer from lower energy density compared to batteries. By embedding redox-active nickel oxide (NiO) nanoparticles into graphene electrodes, we enhance the energy density of these supercapacitors while maintaining high power. The NiO nanoparticles were synthesized at the nanoscale and embedded into graphene oxide (GO) using a one-step laser processing technique, resulting in a composite material with improved electrochemical properties. High specific capacitance for a discharge current density of 0.25 A g-1 is 1420 F g-1 in 6 M KOH. Moreover, by tracking the crystallographic X-ray diffraction (XRD) pattern of the composite electrodes upon electrochemical cycling, we identified the phase transition from NiO to Ni(OH)2. Our results verify the advantages of laser processing to incorporating highly-dispersed NiO nanoparticles into graphene films, which significantly enhances the electrochemical performance of supercapacitors, offering a promising approach for developing high-energy and high-power energy storage devices.

Nitinol Reactive Oxygen Assist Gas Laser Micromachining: Demystifying the Implications Imposed Upon Pseudoelasticity and the Shape Memory Effect for Nickel-Titanium Alloys

Herein, a novel investigation examines a long-pulse microsecond laser cutting process with an oxygen assist gas and the subsequent effects on martensitic phase transformations for binary nickel-titanium alloys. To establish a comprehensive comparative analysis, a reactive oxygen assist gas process, a standard inert argon assist gas process, and athermal femtosecond laser micromachining are studied in order to form a complete analytical assessment of how laser processing can inflict implications upon pseudoelasticity and shape memory. In-situ thermography reveals an approximate 1.5-times increase in thermal area for an argon assist gas when compared to oxygen. In conjunction with thermal analysis, electron backscatter diffraction and optical microscopy demonstrates 1.7 to 25 μm of epitaxial grain recrystallization associated with the elevated level of thermal propagation. Low cycle fatigue testing of pseudoelastic performance realizes a 12.7 % decrease in the achievable upper plateau stress when comparing long-pulse cutting to femtosecond cutting. Furthermore, when the laser power exceeds 30 W, the ultimate tensile strength suffers notable reductions of 25 % and 40 % for the oxygen and argon processes respectively when compared to femtosecond micromachining. Bend and free recovery testing provides insights into shape memory performance of the endothermic phase transformation from B19’ martensite to B2 austenite, revealing marginal ∼1.5 ˚C reductions in the active austenite finish (Af) temperature as laser power was increased from 10 W to 60 W. Lastly, long-pulse laser processing results in notable ∼15 ˚C shifts in the austenite start (As) temperature during the reverse martensite phase transformation from B19’→R→B2.

Influence of transmitting and receiving telescope parameters on measurement resolution of fiber laser doppler vibrometer

<sec>In a laser Doppler vibrometer (LDV), the laser Doppler effect is used to real-time acquire target displacement, velocity, and acceleration. Fiber optic laser vibrometers have received widespread attention in recent years due to their strong environmental adaptability and high integration advantages. With the expansion of detection target distance, higher requirements have been put forward for the measurement resolution of laser vibrometers. The LDV system typically employs a transceiver integrated telescope structure for laser emission and target return light reception. The aperture and focal length of the transceiver telescope determine its basic structure, directly affecting the emission and reception efficiency of laser energy. Additionally, the speckle effect generated by the scattering of rough targets affects the coupling of light energy entering the fiber optic for interference, thereby influencing the LDV measurement resolution.</sec><sec>Based on relevant theories such as Gaussian beam waist transmission, rough target generation, Fresnel diffraction integration, and fiber optic coupling, a transceiver integrated fiber optic laser vibrometer optical field transmission model is established. Numerical simulation and analysis of the emission transmission process of ideal Gaussian laser and the coupling process of surface target echo reception are conducted. Based on the assumption of laser vibrometer speckle noise limitation, an evaluation scheme for the instrument’s noise baseline under rough target return light conditions is proposed. Numerical simulation experiments are conducted for a typical fiber LDV application scenario with an alignment distance of 1 km, a single-mode fiber mode field radius of 5 μm, and a laser wavelength of 1550 nm. The results indicate that the focal length and aperture of the transceiver telescope determine the distribution of system energy utilization and further affect the instrument’s noise baseline. Simulation results show that when the F-number of the transceiver lens reaches 3.3, LDV achieves the highest system energy utilization at this focal length, verifying the correctness of the simulation model. The simulation results can serve as a basis for the design of transceiver lenses for fiber optic laser vibrometers, laser anemometers, and other devices.</sec>

Advances in laser materials and processing technologies: An overview

<p>Laser technology continues to be widely used in industrial terms in various manufacturing processes. This continuously leads to a significant flow of research into the most diverse aspects of this technology, namely in cutting, welding, texturing, engraving operations, and, more recently, three-dimensional (3D) printing of various materials. The most recent technological developments directly related to laser applications have led to new lines of research, which justify the development of some special volumes of high-quality research in this area of knowledge.</p>

Analysis of remelted layers of DD6 single-crystal superalloys by water jet-guided laser processing

This study investigates the characteristics of the remelted layer in DD6 nickel-based single-crystal superalloy processed with a water-jet guided laser (WJGL). Analysis focused on changes in surface morphology, elemental distribution, and crystal structure. WJGL induced periodic thermal stresses, forming distinct ridges within the remelted layer, which differ in morphology from the unprocessed matrix. At the interface, interactions between oxygen and elements such as aluminum, nickel, and chromium led to the formation of oxides, which are strategically evaluated for their role in surface transformations. The oxygen diffusion coefficient, calculated at 1.5×10⁻¹⁵ m²/s using Fick's second law, illustrates the extent of these interactions. The study also reveals thin polycrystalline layers with minimal orientation deviations from the matrix, maintaining the alloy's overall structural integrity. Additionally, the processing direction was found to influence the crystal orientation in the remelted layer, moderated by the turbulence from the water jet. These findings contribute to understanding the microstructural effects of WJGL processing, with implications for optimizing high-temperature alloy applications in aerospace engineering.

Laser surface processing technology for performance enhancement of TENG

<p>The triboelectric nanogenerator (TENG), as a new energy harvesting device, can efficiently harvest mechanical energy from the environment to provide continuous power for electronic devices, which has great potential for powering intelligent distributed network. Laser processing technology, which enables structural, phase, and property control at different scales, can quickly and easily complete the surface patterning of TENG and facilitate efficient energy harvesting. In this work, we outline the working modes and principles of TENG, review the research progress of laser surface processing technology for fabricating TENG in recent years, including laser-induced graphene (LIG), laser ablation, laser carbonization, laser-induced copper, etc., and perspectives on the challenges and future directions for development of laser surface processing for performance enhancement of TENG.</p>

Processing and inspection of high-pressure microfluidics systems: A review.

In the field of microfluidics, high-pressure microfluidics technology, which utilizes high driving pressure for microfluidic analysis, is an evolving technology. This technology combines microfluidics and pressurization, where the flow of fluid is controlled by means of high-pressure-driven devices greater than 10 MPa. This paper first reviews the existing high-pressure microfluidics systems and describes their components and applications. Then, it summarizes several materials used in the microfabrication of high-pressure microfluidics chips, reviewing their properties, processing methods, and bonding methods. In addition, advanced laser processing techniques for the microfabrication of high-pressure microfluidics chips are described. Last, the paper examines the analytical detection methods employed in high-pressure microfluidics systems, encompassing optical and electrochemical detection methods. The review of analytical detection methods shows the different functions and application scenarios of high-pressure microfluidics systems. In summary, this study provides an efficient and advanced microfluidics system, which can be widely used in chemical engineering, food industry, and environmental engineering under high pressure conditions.

Structural color display of polycrystalline diamond processed by femtosecond laser processing

Structural color display of polycrystalline diamond processed by femtosecond laser processing

Selective laser processing of particle accelerator beam screen surfaces for electron cloud mitigation

Laser-induced surface roughening is a technique that facilitates the reduction of secondary electron emission (SEE) from materials, which is crucial for mitigating electron cloud (EC) formation in particle accelerators, that...

Fabrication of Free-Standing Porous BaTiO Thick Films by Indirect Selective Laser Sintering

The fabrication of free-standing porous thick films of ferroelectric BaTiO3, using a laser-assisted technique, is presented as a novel alternative to conventional methods. This approach adapts Indirect Selective Laser Sintering (ISLS) to create green films in a single laser pass, avoiding the complexities of traditional processes. Using commercial BaTiO3 powder and polyamide 12 as raw materials, laser processing parameters such as scanning laser speed and power were optimized to produce green BaTiO3 thick films with different thicknesses. After laser processing, the films were conventionally sintered and characterized for phase composition, microstructure, porosity, and electrical properties. X-ray diffraction and Raman spectroscopy confirmed the tetragonal BaTiO3 phase, while mercury intrusion porosimetry revealed a bimodal pore distribution. Impedance spectroscopy demonstrated a positive temperature coefficient of resistivity (PTCR) effect, with a peak resistivity near the Curie temperature. The PTCR behavior is hypothesized to arise from better oxygen adsorption due to the porosity and oxygen vacancies generated during sintering by carbon residues from polyamide degradation. The results demonstrate that ISLS is a versatile technique for producing high-quality, free-standing porous ceramic thick films with potential for a wide range of applications.

Surface modification of Zr–Nb alloy by nanosecond pulse laser processing

The effect of nanosecond pulse laser processing of the Zr–1% Nb alloy surface of specimens in the annealed state and after their two-stage deformation treatment by abc-pressing and rolling has been investigated. The morphology of the modified surface of specimens is described using optical and scanning microscopy. Furthermore, the microrelief formed as a result of vaporization and melting of a thin layer of material subjected to laser processing is evaluated quantitatively. Durometric measurements were conducted to ascertain the hardness of the near-surface layer and the impact of laser-induced shock waves on its hardness. The electron backscattering diffraction (EBSD) analysis data were employed to describe the structure of the specimens in the near-surface layer. The influence of the initial grain size on the quality of the modified surface, as well as on the depth and hardening of the near-surface layers has been established.

Preparation of Aluminum-Based Dual-Gradient Surfaces for Directional Droplet Transport by Bioinspired Sarracenia Microstructures.

Inspired by the ultrafast directional water transport structure of Sarracenia trichomes, hierarchical textured surfaces with specific microgrooves were prepared based on laser processing combined with dip modification, in response to the growing problem of freshwater scarcity. The prepared surfaces were tested for droplet transport behavior to investigate the relationship between the surface structure and the driving force of directional water transport and their effects on the water transport distance and water transport velocity. The results showed that surfaces with a superhydrophobic background associated channels of multirib structures, and a dual-gradient surface of gradient hydrophobic background associated channels with gradient structure performed the best in terms of water transport efficiency. In addition, the water transport process of different samples under Mode II was simulated by CFD, and the dynamic evolution of water film mode formation was obtained to be divided into four phases, including film formation, transition state, mode formation, and stable water transport. This study provides a good reference for the development and preparation of surfaces for directional water transport.

Influence of Different Spot Pattern Lasers on Cleaning Effect of TC4 Titanium Alloy.

This study employed different spot pattern lasers to clean the oxide film on the surface of a TC4 titanium alloy. The variation in temperature field and ablation depth during the laser cleaning process was simulated by establishing a finite element model. The effects of various laser processing parameters on the micromorphology, elemental composition, and surface roughness of the TC4 titanium alloy were analyzed. The results show that as the laser energy density increases, both the temperature field and ablation depth increase as well. Under optimal laser processing parameters, the laser energy density is 5.27 J/cm2, with a repetition frequency of 300 kHz and a scanning speed of 6000 mm/s. A comparison of the cleaning effects of Gaussian pulse lasers and Flat-top pulse lasers reveals that the Gaussian pulse laser causes less damage to the TC4 titanium alloy, resulting in lower oxygen content and roughness values after cleaning compared to Flat-top pulse laser cleaning.

Laser Preparation and Underwater Drag-Reduction Performance of Secondary Fractal–V Groove Composite Structures on the Surface of Equal-Diameter Revolution Bodies

The reduction of drag for both aircraft and underwater equipment has the potential to reduce their overall energy consumption. Consequently, research into the drag-reducing performance of metal surfaces has significant practical applications. However, there has been more research on the machining of grooves on flat surfaces and inside tubes and less research on the structure of drag-reducing grooves on the outside of circular rods. This paper presents a study in which laser etching technology is employed to machine a range of secondary fractal topologies and V-groove composite structures on the surface of equal-diameter stainless-steel bodies of revolution. The influence of different parameters on the surface properties of stainless-steel materials is analysed through the use of auxiliary positioning tools, adjustments to laser processing parameters and scanning path schemes, as well as the characterisation of the surface morphology of the processed stainless steel using super-depth microscopy, scanning electron microscopy, and other techniques. Subsequently, an underwater drag-reduction tester is employed to assess the drag-reduction efficacy of the optimised secondary fractal composite structure on the surface of the stainless-steel equal-diameter body of revolution. Subsequently, particle image velocity (PIV) tracking technology is employed to assess the surface flow field velocity and overall velocity average of the secondary fractal composite structure. The findings indicate that the secondary fractal composite structure exhibited a drag-reduction effect on the surface of the stainless-steel body of revolution only when the primary main groove had a width of 0.1 mm. Furthermore, an increase in the Reynolds number Re within the range of 4000 to 7000 resulted in a notable enhancement in the drag-reduction efficacy of the secondary fractal composite structure on the surface of the stainless-steel body of revolution. At Re values of 5000, 6000, and 7000, the corresponding drag-reduction rates were observed to be 5.15%, 5.28%, and 5.40%, respectively.

Determining the influence of technological parameters of the laser processing of plastic cards edges on improving their wear resistance

The object of this study is plastic cards for various purposes, which are a multilayer structure. The main factors affecting the wear of cards are environmental influences, storage and use conditions, and equipment for reading our personalized information. During the operation of plastic cards, the most common defects are peeling of the top protective layer and violation of the integrity of the card structure. An increase in the frequency of such operational defects may be caused at the production stage by the peculiarities of a die-cutting process. The subject of the study is to determine the optimal technological parameters for laser processing of plastic cards in order to improve their quality characteristics, in particular, wear resistance. The process of card wear was simulated by exposure to chemical and mechanical factors. The study was conducted using a standard procedure. The new methodology includes a combination of classical tests: a combination of chemical and dynamic effects and the introduction of a washing test. To solve the existing problem, it was proposed to improve the technological process by introducing laser edge processing of plastic cards after die-cutting. A set of experimental studies on resistance to transverse, longitudinal bending and twisting revealed that the wear resistance of cards after laser edge treatment increased by 12 % compared to untreated cards. It was established that for cards made of polyvinylidene chloride, processing with a CO2 laser with a power of 25.5 W and a diameter of the laser beam of 1.5 mm is the most rational. It has been confirmed that this laser processing technique makes it possible to strengthen the chemical bonds between the layers of the body of a plastic card

Mechanistic insights into waterjet-guided laser grooving of silicon: Impact of ablation dynamics, oxide formation, and thermal stress

Waterjet-guided laser machining of silicon offers precision with minimal heat-affected zones (HAZs), but understanding the mechanisms behind laser-material interactions remains essential. This study first utilizes orthogonal experiments to reveal fundamental relationships between processing parameters (scanning cycle, laser fluence, scanning velocity, and waterjet pressure) on groove depth and the depth-to-HAZ ratio. These findings guide the in-depth investigation of laser-material mechanisms. The results indicate that the ablation rate decreases with increasing scanning cycles, a phenomenon primarily attributed to the different absorption rates of 532 nm laser light between silicon and silicon dioxide. This conclusion is supported by x-ray photoelectron spectroscopy(XPS) results, which reveal that the accumulation of silicon dioxide occurs as the scanning cycles increase. Additionally, a near-linear relation between the ablation rate and laser fluence is observed, as the ablated area is continuously exposed to high laser intensity regions. However, increasing laser fluence also leads to diminished processing quality due to greater thermal deformation in non-ablating regions. Last, increased scanning velocity is found to cause rougher surfaces, as insufficient heat diffusion leads to higher thermal stress and results in micro-crack formations. The results provide a detailed understanding of the laser-induced transformations in the material and highlight optimal conditions for reducing thermal damage while maintaining machining efficiency. This study advances the field of laser processing by offering insights into the mechanisms governing oxide formation, thermal cracking, and material deformation during silicon grooving, providing the foundation for future exploration of laser-material interaction dynamics.

Thermocycling test of a titanium-carbon fiber adhesive joint produced using laser texturing technology

In spacecraft load-bearing structures, adhesive bonding of titanium alloy and composite material parts is often used. To increase the strength of the adhesive bond of the titanium-carbon fiber reinforced plastic pair, preliminary treatment of the bonded surfaces is necessary. In this paper, it is proposed to use laser texturing to process the metal surface. The main objective of the study is to experimentally determine the strength characteristics of the adhesive bond of carbon fiber reinforced plastic and titanium alloy with different modes of laser processing of the metal surface and to determine the effect of thermal cycling on the samples of the adhesive bond. The surface of the OT-4 titanium alloy was laser processed in different modes, after which the samples were glued with VK-9 and LOCTITE® EA 9394 AERO glue. The glued samples were subjected to thermal cycling in a vacuum chamber in the temperature range from –150 to +150 °C. Shear testing of adhesive bond samples showed that laser texturing increases bond strength by an average of 60% for LOCTITE® EA 9394 AERO adhesive and by 142% for VK-9 adhesive. Samples with laser texturing have a cohesive nature of failure on carbon fiber. During thermal cycling, most samples show a slight decrease in adhesive bond strength by an average of 6...8%. The results show that the use of laser processing to prepare titanium alloy before bonding with composite material is a promising method for increasing the strength of adhesive bonds for spacecraft components.