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A Study of Laser Beam Welding, Gas Tungsten Arc Welding and High Temperature Brazing Processes on Micro hardness and Tensile Strength of AISI Type 316 Stainless Steel
摘要： Thin wall joints for elevated temperature (~550 °C) applications can be prepared by Laser Beam Welding (LBW), Gas Tungsten Arc Welding (GTAW) and High Temperature Brazing (HTB) methods. The joints have been made and tests such as helium leak test (HLT), micro hardness test and tensile test were carried out. A study has been performed on these joining techniques to recognize the suitable method for high temperature applications. No observable leak was identified during HLT. Microstructures shows dissimilarity in solidification morphology due to disparity in heat sources. It has been identified that the joint made by brazing process having higher micro hardness value. Further, it has been observed that LBW joints have better mechanical properties than GTAW joints and HTB joints.
关键词： GTAW,Micro hardness,AISI 316 stainless steels,Tensile properties,High temperature brazing,Microstructures,Nd:YAG Laser
更新于2025-09-12 10:27:22
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Laser welding of AlSi10Mg aluminium-based alloy produced by Selective Laser Melting (SLM)
摘要： Additive manufacturing can produce very complex and highly integrated parts that cannot be manufactured by traditional methods. In many of its applications, the AM-manufactured part may be a very small part of the whole, and therefore it has become increasingly important to find suitable attachment methods for printed parts. The aim of this study was to find out the laser weldability of the printed AlSi10Mg material without filler material. The laser used in these welding experiments was Yb:YAG disk laser. The laser wavelength was 1030 nm and the maximum output power on the workpiece surface was 4 kW. AlSi10Mg is a widely used material in parts that are produced utilizing the SLM technique. The material has very good corrosion resistance properties, good electrical conductivity and excellent thermal conductivity. AlSi10Mg has proven to be much easier to print than steel materials, so it is a popular material also in prototype production. Based on welding tests, laser welding without filler material is suitable for AlSi10Mg material and the static strength of the weld is reasonably good compared to the base material. However, AlSi10Mg can be found to be challenging due to its composition.
关键词： Selective Laser Melting (SLM),AlSi10Mg,Yb:YAG disk laser,Laser welding,Additive Manufacturing (AM)
更新于2025-09-12 10:27:22
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Effect of the surface texturing treatment with Nd: YAG laser on the wear resistance of CoCr alloy
摘要： The present work aims to explore the tribological behavior of the laser texturing process with different patterns on a Co based alloy using a pulsed Nd: YAG laser. Different parameters such as peak power, speed and spot diameter of the laser were explored for the experimental setting. The microstructural analysis was performed using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and nanoindentation tests. The influence of the different textured patterns of the tribological performance tested with a pin-on-disc tribometer under lubricated sliding condition was evaluated. The results showed that typical interdendritic structures in the as-cast CoCr alloy condition were refined due to the heat input and fast cooling rate during the laser treatment. The refined microstructure showed less volumetric loss resulting in a increment of wear resistance and a better tribological performance than as-cast alloy. The correlation among laser parameters, microstructural effect and their influence in wear resistance is discussed.
关键词： Nd: YAG laser,laser texturing,CoCr alloy,tribological behavior,wear resistance
更新于2025-09-12 10:27:22
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Assessment of Vitreous Structure and Visual Function after Neodymium:Yttrium–Aluminum–Garnet Laser Vitreolysis
摘要： Purpose: Neodymium:yttriumealuminumegarnet (Nd:YAG) laser treatment is performed on vitreous ?oaters, but studies of structural and functional effects with objective outcome measures are lacking. This study evaluated Nd:YAG laser effects by comparing participants with vitreous ?oaters who previously underwent laser treatment with untreated control participants and healthy persons without vitreous ?oaters using quantitative ultrasonography to evaluate vitreous structure and by measuring visual acuity and contrast sensitivity function to assess vision. Design: Retrospective, comparative study. Participants: One eye was enrolled for each of 132 participants: 35 control participants without vitreous ?oaters, 59 participants with untreated vitreous ?oaters, and 38 participants with vitreous ?oaters previously Nd:YAG-treated. Of these, 25 were dissatis?ed and sought vitrectomy; 13 were satis?ed with observation. Methods: The 39-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-39) to assess participant visual well-being, quantitative ultrasonography (QUS) to measure vitreous echodensity, and best-corrected visual acuity (BCVA) and contrast sensitivity function (CSF) to evaluate vision. Main Outcome Measures: Results of NEI-VFQ-39, QUS, BCVA, and CSF. Results: Compared with control participants without vitreous ?oaters, participants with untreated vitreous ?oaters showed worse NEI-VFQ-39 results, 57% greater vitreous echodensity, and signi?cant (130%) CSF degradation (P < 0.001 for each). Compared with untreated eyes with vitreous ?oaters, Nd:YAG-treated eyes had 23% less vitreous echodensity (P < 0.001), but no differences in NEI-VFQ-39 (P ? 0.51), BCVA (P ? 0.42), and CSF (P ? 0.17) results. Of 38 participants with vitreous ?oaters who previously were treated with Nd:YAG, 25 were dissatis?ed and seeking vitrectomy, whereas 13 were satis?ed with observation. Participants seeking vitrectomy showed 24% greater vitreous echodensity (P ? 0.018) and 52% worse CSF (P ? 0.006). Multivariate linear regression models con?rmed these ?ndings. Conclusions: As a group, participants previously treated with Nd:YAG laser for bothersome vitreous ?oaters showed less dense vitreous, but similar visual function as untreated control participants with vitreous ?oaters. Because some treated eyes showed less dense vitreous and better visual function than those of untreated control participants, a prospective randomized study of Nd:YAG laser treatment of vitreous is warranted, using uniform laser treatment parameters and objective quantitative outcome measures.
关键词： Neodymium:yttriumealuminumegarnet (Nd:YAG) laser,vitreous ?oaters,best-corrected visual acuity,quantitative ultrasonography,contrast sensitivity function
更新于2025-09-12 10:27:22
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AIP Conference Proceedings [AIP Publishing TECHNOLOGIES AND MATERIALS FOR RENEWABLE ENERGY, ENVIRONMENT AND SUSTAINABILITY: TMREES19Gr - Athens, Greece (4–6 September 2019)] TECHNOLOGIES AND MATERIALS FOR RENEWABLE ENERGY, ENVIRONMENT AND SUSTAINABILITY: TMREES19Gr - Effect of laser pulses on ion release behavior of Ti-base alloys
摘要： Modifications achieved by laser irradiation on titanium-base alloys were studied to promote their surface properties in addition to the ion release behavior. Laser pulses was use for three different types of Ti-base alloys; commercial pure Ti alloy, Titanium-Tantalum alloys, and Nickel-Titanium alloys. The alloys were manufactured by using powder technology then the Nd: YAG laser pulses were used. The characterizations of samples have been done which includes; microstructure observation, XRD, surface roughness (AFM), and ion release analysis. The microstructure observation show that the use of Nd: YAG laser pulses was effective method to provide energy focused on one spot especially at the surface which produce complex microstructures and roughening the surfaces to increase effective surface area. XRD showed the sintering process under controlled atmosphere produced samples with complete sintering reaction. AFM results show the same response to the laser irradiation and the slight differences in the roughness values was observed. From the results of ion release analysis it was found that the release of Ti ion rise in first three days and after that released of Ti ions begin to stabilize after the laser pulses. The appearance of a slight differences in the amount of titanium ions that released from the samples for each group was due to the influence of the surface activation process that have been employed as a primary treatment which effect on the stability and thickness of the titanium oxide.
关键词： Ion release,Powder technology,Nd:YAG laser,Advance materials
更新于2025-09-12 10:27:22
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Pulse-Propagation Modeling and Experiment for Femtosecond-Laser Writing of Waveguide in Nd:YAG
摘要： In this work, unidirectional pulse propagation equation (UPPE) modeling is performed to study the nonlinear laser-mater interaction in silicon and Nd:Y3Al5O12 (Nd:YAG) crystals. The simulation results are validated with reported experimental results for silicon and applied to Nd:YAG crystals with experimental validation. Stress-induced waveguides are written in Nd:YAG crystals using 515 nm, 300 fs pulses at a 1 kHz repetition rate. Waveguides having a mean propagation loss of 0.21 ± 0.06 dB/cm are obtained, which is lower than the previous reported values for Type-II waveguides written in Nd:YAG crystals. The modeling and experimental results consistently show that the modi?cation (waveguide track) depth increases with input energy. A detailed analysis is presented to control the modal properties of the waveguide in the context of UPPE simulation.
关键词： stress-induced waveguide writing,nonlinear pulse propagation,femtosecond laser writing,Nd:YAG crystal
更新于2025-09-12 10:27:22
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Investigations on vacuum sintered ytterbium-doped YAG ceramic: a laser–host material
摘要： Laser–host ceramics are a new class of materials and have proved to be a good alternative to the single-crystals. They can be produced in large size with higher concentration of activator ions having more homogeneity which is dif?cult to achieve with the conventional single-crystal growth technology. Ytterbium (Yb)-doped yttrium aluminium garnet (YAG) is a very attractive laser–host material because of its broad emission band, low quantum defect, no excited state absorption or up-conversion loss and wide range of tunability. In the present work, 10 atm% Yb-doped YAG transparent ceramic was fabricated using nano-powder technology and vacuum sintering. Single-phase nano-powders of Yb:YAG were synthesized by a co-precipitation method and thereafter sintered under vacuum at 1750?C for 5 h. The as-sintered ceramic samples are of dark greenish colour which is attributed to the reduction of Yb3+ to Yb2+ during vacuum sintering. However, after annealing in air at 1350?C for 8 h they retain their natural colour attributed to the transformations from Yb2+ to Yb3+. The transmission spectra of the as-sintered polished ceramics show the presence of broad absorption bands near 250, 380, 480 and 630 nm due to the electronic transitions in the Yb2+ ion. These bands disappear after annealing in air. The well-established bands due to transitions in Yb3+ were observed between 900 and 1000 nm.
关键词： sintering,Optical ceramics,Yb:YAG
更新于2025-09-12 10:27:22
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Micromachining on Al-Sic Based Metal Matrix Composite Using DPSS Laser
摘要： Aluminum silicon carbide is a metal matrix composite largely used where strength to weight ratio and high thermal conductivity is primary in design criteria. It has wide application in Aerospace components, Automobiles & electronics industries. Present work deals in micro-grooving of this hard to machine material is carried out by diode pumped solid state pulsed Nd:YAG Laser. The experimental plan is carried out by CCD (central composite design) based on RSM (response surface methodology).Also the analysis of variance test is carried out to check the adequacy of the fitted regression mathematical models. Proper ranges of process parameters such as pulse width, pulse frequency, amount of current, assist air pressure were purposed. Screening test shows O2 as assist gas when used 0.2 to 1 kgf/cm2 pressure range gives best result because of its advantage during laser material interaction. The responses are taken as upper width deviation, lower width & depth deviation of micro-groove produced on Al-SiC material. The interaction effects of different parameters on responses are analyzed through surface plots generated. Optimal process parametric conditions are found out by utilizing meta-heuristic based search algorithm MOPSO (multi objective particle swamp optimization) technique.
关键词： MMC,ANOVA,Nd:YAG,RSM,SEM
更新于2025-09-12 10:27:22
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A 142 W Ho:YAG laser single-end-pumped by a Tm-doped fiber laser at 1931 nm
摘要： In this paper, a high-power Ho:YAG laser in-band pumped by a Tm-doped fiber laser at 1931 nm is reported. A maximum output power of 142.2 W is achieved at 2091 nm using a single-end-pumped configuration, corresponding to a slope efficiency of 56.7%. This is, to the best of our knowledge, the highest output power directly generated by bulk Ho-oscillators in the 2.1 μm spectral region.
关键词： fiber laser,Ho:YAG,solid state laser
更新于2025-09-12 10:27:22
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Preliminary outcome of non-ablative vaginal Erbium laser treatment for female stress and mixed urinary incontinence
摘要： Objective: This prospective study presents a preliminary result to compare the clinical ef?cacy of patients with stress urinary incontinence and mixed urinary incontinence using minimal invasive Er:YAG vaginal laser. Materials and methods: A total of 20 patients were included, in which were 10 patients with SUI and 10 patients with MUI (stress and urge incontinence), and underwent a 2940 nm Er:YAG laser with a special SMOOTH mode in an outpatient of?ce without anesthesia or postoperative medications. All patients completed two sessions of treatment with an interval time of 28 days. At three months after treatment, all patients were asked to a clinical visit for evaluate the clinical outcome by pre-treatment and post-treatment ICIQ-SF questionnaire. At pretreatment and 3 months after the completion of two therapy sessions, patients were asked to answer the ICIQ-SF questionnaire. The questionnaire consists of three scales for assessment of the treatment outcome of urinary incontinence as: no change (no change score), improvement (decrease score 1e5), and strong improvement (decrease score >5) for two groups of patients with SUI and MUI. All the results were compared by Student's t test with two way analysis of variance between the two groups. Results: A total of 20 patients presented with SUI symptom relief and improvement with treatment satisfaction. All 10 patients with SUI reported improvement after vaginal laser treatment, 70% with marked improvement and 30% with improvement. All 10 patients with MUI also had improvement, 40% with marked improvement and 60% with improvement. There was no statistically signi?cant difference in the treatment outcome between the two groups. Conclusions: Vaginal Erbium laser produce provides vaginal collagen remodeling and synthesis that may repair and restore the pelvic ?oor function. Despite of sample limitation and short follow up, this treating procedure presented a good and a safe clinical outcome in patients with SUI and with MUI by assessment of ICIQ-SF questionnaire.
关键词： Stress urinary incontinence,Er:YAG vaginal laser,Urge incontinence,Mixed urinary incontinence
更新于2025-09-12 10:27:22