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A Model for Predicting the Geometry of Crater on Grinding Wheel Surface Ablated with a Single Pulsed Laser
摘要： In this paper, a three dimensional transient heat transfer model for predicting the 3D geometry of crater and its cross sectional profile on grinding wheel surface ablated by a single pulsed Nd: YAG laser is covered. The model considers the heterogeneity of wheel structure, the variation of energy in a pulsed laser input to the wheel, heat transfer by conduction, convection, radiation and the thermo-physical and optical properties of bond and grit while predicting the temperature distribution in the irradiated region using COMSOL Multiphysics? 5.2 package. From this temperature distribution, the shape of crater was predicted. Crater depth predicted was validated with the published results confirming the suitability of this model for predicting the shape of crater in single pulsed laser ablation of wheel surface. Post modeling analysis gives insights of the process mechanism of laser dressing and the parameters affecting the crater geometry. Future scope and implementation of this model is discussed in detail.
关键词： single-pulse laser ablation,laser dressing of grinding wheels,wheel structure model,crater geometry
更新于2025-09-12 10:27:22
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Fabrication of surfaces with reduced friction using nanosecond laser
摘要： In this paper a short i.e. nanosecond pulse laser ablation is utilized to fabricate trapezoidal shaped microstructures i.e. riblets that are known to reduce friction. They can be applied for example in turbomachinery applications to make system more economical by reducing the wall shear stress on flow surfaces. Previously, these structures have been manufactured using different methods like grinding and ultrashort pulse lasers. The methods used before have their disadvantages and therefore they cannot be utilized in all applications. By using the nanosecond pulse laser instead of the shorter pulses, it is possible to manufacture riblets with a high fabrication speed and economically. Although a quality of the nanosecond pulse laser manufactured riblets is not as good as ones fabricated with the ultrashort pulse lasers, they are still able to reduce friction in the turbomachinery application.
关键词： micromachining,tubomachinery,nanosecond laser,airfoil,riblet,laser ablation,microstructures
更新于2025-09-12 10:27:22
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Laser—synthesised Ag <sub/>2</sub> S nanoparticles in liquid: effect of laser fluence on structural and optical properties
摘要： In this study, we report for the first time the preparation and characterization of silver sulfide nanoparticles (NPs) by one-step laser ablation of the silver target in thiourea aqueous solution without using a catalyst. The effect of laser fluence on the crystal structure, morphology, size and elemental composition of Ag2S NPs was investigated. X-ray diffraction (XRD) results show Ag2S NPs are polycrystalline with monoclinic phase and the variation in laser fluence affects the crystallinity of the synthesized NPs. The optical energy gap decreases from 2.2eV to 1.6eV as the laser fluence increases from 2.38 Jcm-2 to 6.77Jcm-2. Transmission electron microscope (TEM) investigation confirms the formation of spherical Ag2S NPs and nanosheets morphologies and the particle size is found increases from 30nm to 65nm when the laser fluence increases from 2.38 Jcm-2 to 6.77Jcm-2. The Raman spectra of Ag2S NPs show the presence of six active Raman peaks and their intensity increased with laser fluence.
关键词： Silver sulfide,Laser ablation,Nanoparticles,Laser fluence
更新于2025-09-12 10:27:22
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Aluminum pretreatment by a laser ablation process: influence of processing parameters on the joint strength of laser welded aluminum – polyamide assemblies
摘要： Laser welding of metal – polymer assemblies is an innovative bonding process. It was already demonstrated that laser surface pretreatments of aluminum (Al), prior to laser welding with a polymer, impacts joints strength. This work adopts a design of experiments (DoE) approach to investigate the influence of several Al laser ablation parameters on joint strength of laser welded Al – polyamide (PA6.6) assemblies. Significant parameters were highlighted, process window was outlined, and optimal parameters were identified. After assembly failure, the joint area was evaluated using optical microscopy. Depending on the laser ablation parameters, the joint area can be enhanced resulting in a significant increase in the corresponding bearable shear load.
关键词： Metal-polymer assemblies,Laser ablation,Laser beam welding,Hybrid joining
更新于2025-09-12 10:27:22
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Comparative Experimental Investigation of Micro-channel Fabrication in Ti Alloys by Laser Ablation and Laser-induced Plasma Micro-machining
摘要： Reliable and improved micro-fabrication processes for high-strength alloys are needed due to their increasing use in micro-scale applications. Laser-Induced Plasma Micro-Machining (LIPMM) has been shown to have several advantages over conventional direct laser ablation. In this study micro-channels are fabricated in Ti-6Al-4V, one of the difficult-to-machine materials, to compare the micro-manufacturing capabilities of direct laser ablation to LIPMM. It has been shown that LIPMM results in much deeper channels and higher aspect ratios and better machining consistency than direct laser ablation.
关键词： Micro-Machining,Laser Ablation,Laser-Induced Plasma Micro-Machining (LIPMM),Ti64
更新于2025-09-12 10:27:22
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Femtosecond Laser Micromachining of Metal Thin Films
摘要： In this paper the possibilities of femtosecond laser micromachining of thin-film titanium coatings for elements of microelectronics and optoelectronics are considered. Using pulsed laser deposition in vacuum (wavelength λ = 1030 nm, pulse repetition frequency f = 10 kHz, Emax pulse energy ≈ 150 μJ, pulse duration τ ≈ 280 fs), a thin-film titanium coating was obtained on the surface of the quartz substrate. An example of the formation of an element of a given geometry by selective laser ablation of areas of a deposited metal coating is shown.
关键词： ultrashort laser pulses,precision micromachining,laser ablation,thin metal films
更新于2025-09-12 10:27:22
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Preparing TEM Specimens and Atom Probe Tips by Laser Machining
摘要： Preparation of electron-transparent thin specimens can be costly in terms of time and is often challenging. Materials and products are becoming more complex, and device components are getting smaller each year. On the other hand, analysis and diagnostic methods become more exacting. Lack of time and high costs for diagnostics force companies to speed up, simplify, and customize the analysis process. Ultra-short-pulsed laser-based sample preparation can speed up the process and make possible new sample geometries. This article shows the advantages of this technology and how it can be used to prepare TEM lamellas (H-Bar) and multiple APT tips or pillars.
关键词： ultra-short-pulsed laser,laser ablation,APT tips,heating effects,TEM lamellas
更新于2025-09-12 10:27:22
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Chemical analysis of a lunar meteorite by laser ablation mass spectrometry
摘要： The lunar meteorite Sayh al Uhaymir 169, that contains KREEP rich material, was investigated with our miniature laser ablation time-of-flight mass spectrometer to simulate the expected performance of in-situ measurements on the surface of a planetary body. The abundances of the major elements on the KREEP part of the rock were measured and plotted on a two-dimensional surface map to identify different mineral phases in the sample. The element distribution maps reveal the grain boundaries and allow identification of individual minerals and their major and trace element compositions. In the second measurement campaign the instrument was coupled with a HV pulser to increase sensitivity of the measurements. It could be shown that the detection sensitivity for heavy trace elements can be significantly improved while removing light elements from the analyzed ion beam. This study provides also measurements of U, Th and Pb elements present inside a single zircon grain. With the abundances of U and Pb in the zircon grain a preliminary age estimation of the zircon could be made and was found to be in reasonable agreement with ages reported in literature. Moreover, from the Ti concentration in the zircon grain a crystallization temperature was derived. Thus, by employing such an instrument on a planetary surface, scientific useful in-situ measurements on the element composition, the mineralogy, petrology and dating of surface samples can be accomplished.
关键词： Lunar meteorite,Trace elements,Laser ablation mass spectrometry,Crystallization temperature,KREEP material,Zircon
更新于2025-09-12 10:27:22
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[ACS Symposium Series] Fundamentals and Applications of Phosphorus Nanomaterials Volume 1333 || Phosphorus Clusters and Quantum Dots
摘要： Cluster is characterized by its unique role in chemistry and physics due to the fact that it bridges isolated atoms and bulk counterparts. It is also found that the structures and properties of clusters change dramatically with their sizes. Characterized by its diverse bonding patterns, phosphorus clusters have attracted many interests in past years. With the help of laser ablation mass spectrometry and other relative technologies, many kinds of phosphorus clusters have been generated, identified and studied. Their structures and properties are also widely studied by theoretical calculations. This chapter reviews both experimental and theoretical progresses about phosphorus clusters and relative species. On the other hand, the phosphorus quantum dots have attracted a great deal of attention due to its unique structures, properties, and applications in recent years. A quick overview on this topic is also included in the chapter, in order to attract more interests from broad research fields and make a bridge across the cluster study and nanomaterials to benefit scientists in both fields.
关键词： theoretical calculations,laser ablation mass spectrometry,quantum dots,phosphorus clusters,nanomaterials
更新于2025-09-12 10:27:22
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Laser-ablation-synthesized nanoparticles and animal cell lines studies
摘要： Nanoparticles (NPs) synthesized by laser ablation in distilled water were used to study their biological effect on normal and cancer cells. Parameters such as cell morphology, cell proliferation and viability were examined for treated cell lines, and the effect was represented in terms of cells cytotoxicity using standard procedures. The study reveals the higher cytotoxic effect of nanoparticles on cancerous cells of breast, melanoma and colon origin compared to normal fibroblast cells NIH-3T3. Furthermore, DNA fragmentation assay results demonstrated the apoptosis mediated cell death in nanoparticle-treated cancer cells. The distinct role of nanoparticles in normal and cancer cells of different origin showed that nanoparticles were specific to cause cytotoxicity in particular cancer cells type. NPs exhibit cytotoxic effects in cancer cells by inducing apoptosis. These studies provide fundamental evidence for the easy, simple and safe mode of nanoparticles synthesis and their application in cancer cells death.
关键词： nanoparticles,Cancer cells,cytotoxicity,laser ablation
更新于2025-09-12 10:27:22