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The Effects of Laser Parameters and the Ablation Mechanism in Laser Ablation of C/SiC Composite
摘要： The e?ects of laser parameters and the ablation mechanism in laser ablation of a carbon ?ber reinforced silicon carbide (C/SiC) composite are investigated in the present study. Six di?erent power densities are provided, as well as six levels of pulse numbers, and then ablation experiments are conducted for the C/SiC composite, induced by a pulsed laser. Based on the experimental results, the characteristics of surface morphology and ablation behavior are discussed. It is revealed that the surface morphology of the C/SiC composite under laser irradiation usually includes three regions: the center region, the transition region, and the border region. With the increase of laser power density, the ablation of the center region becomes severe, surface cracks occur, and more spherical SiC particles are found in the transition region. As for scenarios involving multiple pulses, the damage occurs in the center region at low power density limits, within the ?rst two layers below the surface. However, if the power density is relatively high, an ablation pit occurs in the center region when the pulse number is larger than 50. Meanwhile, the transition region and the border region diminish with increase of the pulse number. It is noted that both the power density and pulse number have noticeable e?ects on surface morphology and ablation behavior during laser ablation, which is helpful for material design and performance evaluation of C/SiC composites.
关键词： Surface morphology,C/SiC composite,Ablation mechanism,Laser ablation,Scanning electron microscopy (SEM)
更新于2025-09-12 10:27:22
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Laser additive manufacturing of oxide dispersion strengthened steels using laser-generated nanoparticle-metal composite powders
摘要： A new route for the synthesis of powder composites suitable for processing with laser additive manufacturing is demonstrated. The powder composites, consisting of micrometer-sized stainless steel powder, homogenously decorated with nano-scaled Y2O3 powder particles, are manufactured by laser processing of colloids and electrostatic deposition. Consolidated by laser metal deposition and selective laser melting, the resulting specimens show superior mechanical properties at elevated temperatures, caused by the nano-sized, homogenously distributed dispersoids.
关键词： Laser additive manufacturing,Pulsed laser ablation in liquids,Selective Laser Melting,Oxide dispersion strengthened materials,ODS
更新于2025-09-12 10:27:22
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A new approach to coat PA12 powders with laser-generated nanoparticles for selective laser sintering
摘要： The modification of selective laser sintering (SLS) powder materials by nanoadditives offers the possibility to adapt the powder properties to the laser sintering process or the resulting part properties. To avoid agglomeration of the nanofiller, a new approach in which surfactant-free laser-generated colloidal nanoparticles are adsorbed onto the polymer surface directly in an aqueous solution is demonstrated. Based on this novel approach, polyamide 12 (PA12) powders are decorated with metal and oxide nanoparticles and processed via SLS. Electron microscopy and confocal laser scanning imaging are utilized to analyze the dispersion of the filler.
关键词： selective laser sintering,laser additive manufacturing,polymer powders,pulsed laser ablation in liquids,nanoparticles
更新于2025-09-12 10:27:22
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Study on processing characteristics and mechanisms of thermally assisted laser materials processing
摘要： Nanosecond pulsed lasers have been widely applied to interact with and characterize many di?erent materials, and industrial users are exploring more avenues for various application processes. For the purpose of achieving broader application, the current challenge is to achieve a high processing e?ciency for laser materials processing. In this study, thermally assisted laser materials processing (TALMP), which introduces heat from an external source to increase the workpiece material's temperature and make it easier to carry out ablation or modi?cation, was developed and investigated. Moreover, to investigate the materials processing characteristics and mechanisms of TALMP, practical applications using TALMP, including surface ablation on WC-Co, and surface polishing on additive manufactured Ti-6Al-4V, were carried out. The results showed that TALMP can be successfully applied to various materials by di?erent laser materials processing applications. Due to the workpiece material's high temperature and heat content, the coupling between laser and target materials can be enhanced; thus, physical ablation and modi?cation for laser surface ablation can be achieved e?ectively. However, with a high o?set temperature, a little decrease of ablation accuracy and quality could occur, and a two-step approach is proposed to eliminate this unwanted e?ect. Moreover, this strategy is proven to be able to achieve the desired surface ablation with high e?ciency and high-quality surfaces. For thermally assisted surface polishing, due to higher temperature ?eld with long duration, a smoother and ?atter polished surface can be obtained more easily. The experimental results proved the superiority and versatility of TALMP.
关键词： Laser polishing,Thermally assisted,Laser materials processing,Laser ablation
更新于2025-09-12 10:27:22
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High-Energy-Density Physics and Laser Technologies
摘要： This paper is devoted to the jubilee of I.M. Khalatnikov, the founder and the first director of the Landau Institute for Theoretical Physics of the Russian Academy of Sciences. I.M. Khalatnikov organized a first-class institute the studies at which cover a broad spectrum of research directions. The plasma and lasers department of the Institute conducts research on plasma physics problems, laser–matter interaction, questions pertaining to laser applications, and hydrodynamics problems. Much attention is given to solid-state physics with an emphasis on the behavior of matter in extreme conditions under intense laser irradiation. A number of new results are presented: the behavior of metals in two-temperature states (when the temperature of the electron subsystem of a metal is much greater than the temperature of the ion subsystem due to ultrafast laser heating); determining the boundaries of existence of a single-wave propagation mode of elastoplastic shock waves in ductile metal crystals; the formation of a laser torch from target materials and liquids under metal laser ablation of a metal into the surrounding liquid; the physical–mechanical consequences (melting, capillarity, recrystallization) of nonuniform (along the irradiated surface) energy dissipation caused by the interference of plasmon–polariton and laser electromagnetic fields.
关键词： laser–matter interaction,plasma physics,laser ablation,hydrodynamics,two-temperature states,plasmon–polariton,solid-state physics,high-energy-density physics,laser technologies,elastoplastic shock waves
更新于2025-09-12 10:27:22
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Surface structuring of Kapton polyimide with femtosecond and picosecond IR laser pulses
摘要： Pulsed laser ablation is one of the most efficient and clean methods for high-precision processing and modification of polymers and biomaterials. Polymer ablation has been extensively investigated with ultraviolet lasers while little attention has been given to the infrared (IR) region, which becomes particularly interesting with the recent advances in ultrashort laser technologies. Here, we report the results of a comparative study on 1030-nm ultrashort laser structuring of Kapton polyimide, a polymer important in a variety of applications, with direct comparison of 247-fs and 7-ps laser pulses. The laser-induced damage thresholds for both pulse durations have been determined and the femtosecond laser threshold has been found to be considerably lower than that for picosecond pulses (by a factor of ～ 3.5). Both femtosecond and picosecond laser–produced craters have been thoroughly investigated as a function of pulse energy and focusing conditions. It has been demonstrated that femtosecond laser pulses enable accurate polyimide structuring while picosecond irradiation regimes result in a number of undesired effects such as re-deposition of the ablation debris, surface swelling, and the formation of high rims around the ablation craters. The mechanisms of polyimide ablation with femtosecond and picosecond IR laser pulses are discussed.
关键词： crater profile,swelling,laser ablation,damage threshold,laser processing,ultrashort laser pulses,multiphoton absorption,polymers,polyimide
更新于2025-09-12 10:27:22
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Grain refining in weld metal using short-pulsed laser ablation during CW laser welding of 2024-T3 aluminum alloy
摘要： The 2024 aluminum alloy is used extensively in the aircraft and aerospace industries because of its excellent mechanical properties. However, the weldability of 2024 aluminum alloy is generally low because it contains a high number of solutes, such as copper (Cu), magnesium (Mg), and manganese (Mn), causing solidification cracking. If high speed welding of 2024 aluminum alloy without the use of filler is achieved, the applicability of 2024 aluminum alloys will expand. Grain refining is one of the methods used to prevent solidification cracking in weld metal, although it has never been achieved for high-speed laser welding of 2024 aluminum alloy without filler. Here, we propose a short-pulsed, laser-induced, grain-refining method during continuous wave laser welding without filler. Bead-on-plate welding was performed on a 2024-T3 aluminum alloy at a welding speed of 1 m min?1 with a single mode fiber laser at a wavelength of 1070 nm and power of 1 kW. Areas in and around the molten pool were irradiated with nanosecond laser pulses at a wavelength of 1064 nm, pulse width of 10 ns, and pulse energy of 430 mJ. The grain-refinement effect was confirmed when laser pulses were irradiated on the molten pool. The grain-refinement region was formed in a semicircular shape along the solid–liquid interface. Results of the vertical section indicate that the grain-refinement region reached a depth of 1 mm along the solid–liquid interface. The Vickers hardness test results demonstrated that the hardness increased as a result of grain refinement and that the progress of solidification cracking was suppressed in the grain refinement region.
关键词： grain refinement,short pulsed laser,laser welding,laser ablation,2024 aluminum alloy,hot cracking,dendrite fragmentation
更新于2025-09-12 10:27:22
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Lithium Distribution in Structured Graphite Anodes Investigated by Laser-Induced Breakdown Spectroscopy
摘要： For the development of thick film graphite electrodes, a 3D battery concept is applied, which significantly improves lithium-ion diffusion kinetics, high-rate capability, and cell lifetime and reduces mechanical tensions. Our current research indicates that 3D architectures of anode materials can prevent cells from capacity fading at high C-rates and improve cell lifespan. For the further research and development of 3D battery concepts, it is important to scientifically understand the influence of laser-generated 3D anode architectures on lithium distribution during charging and discharging at elevated C-rates. Laser-induced breakdown spectroscopy (LIBS) is applied post-mortem for quantitatively studying the lithium concentration profiles within the entire structured and unstructured graphite electrodes. Space-resolved LIBS measurements revealed that less lithium-ion content could be detected in structured electrodes at delithiated state in comparison to unstructured electrodes. This result indicates that 3D architectures established on anode electrodes can accelerate the lithium-ion extraction process and reduce the formation of inactive materials during electrochemical cycling. Furthermore, LIBS measurements showed that at high C-rates, lithium-ion concentration is increased along the contour of laser-generated structures indicating enhanced lithium-ion diffusion kinetics for 3D anode materials. This result is correlated with significantly increased capacity retention. Moreover, the lithium-ion distribution profiles provide meaningful information about optimizing the electrode architecture with respect to film thickness, pitch distance, and battery usage scenario.
关键词： laser-induced breakdown spectroscopy,3D battery,lithium-ion battery,ultrafast laser ablation,graphite anode
更新于2025-09-12 10:27:22
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Femtosecond Laser Pulse Ablation of Sub-Cellular Drusen-Like Deposits
摘要： Age-related macular degeneration (AMD) is a condition affecting the retina and is the leading cause of vision loss. Dry AMD is caused by the accumulation of lipid deposits called drusen, which form under the retina. This work demonstrates, for the first time, the removal of drusen-like deposits underneath ARPE-19 cell layers using femtosecond laser pulses. A novel cell culture model was created in response to the limited access to primary cell lines and the absence of animal models that recapitulate all aspects of AMD. In the cell culture model, deposits were identified with fluorescent stains specific to known deposit constituents. Trains of sub-10 femtosecond laser pulses from a Ti:Sapphire laser were used to successfully ablate the deposits without causing damage to surrounding cells. this drusen removal method can be used as a potential treatment for dry-stage AMD.
关键词： drusen,ARPE-19,laser ablation,age-related macular degeneration,femtosecond laser
更新于2025-09-12 10:27:22
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Nanosecond laser ablation of the trapezoidal structures for turbomachinery applications
摘要： Correctly designed nature inspired micrometer size grooves i.e. riblets can be used to reduce drag. There exist several methods to manufacture these structures but all of them have their own problems and disadvantages, wherefore they are not perfectly suitable for all real industrial applications. Aim of this paper is to show how a short nanosecond pulse laser ablation can be applied in a micrometer size trapezoidal shape structures i.e. riblets manufacturing for a turbomachinery applications. It is shown that although the quality of the riblets, fabricated with this method, is not as good as with the best possible manufacturing methods, it is still enhancing the properties. Added to this, the processing speed is fast enough and acquisition costs of the system are economic so that method is suitable for the real industrial application. The wind tunnel studies indicate that the fabricated riblets on an airfoil reduce wall shear stress compared to a smooth airfoil without structuring.
关键词： micromachining,nanosecond laser,airfoil,riblet,microstructures,Laser ablation
更新于2025-09-12 10:27:22