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Laser transmission welding and surface modification of graphene film for flexible supercapacitor applications
摘要： When a graphene ?lm is coated onto a ?exible polymer substrate, weak adhesion can cause delamination of the ?lm under mechanical bending. Moreover, as each graphene layer restacks, the performance of the ?lm as an electrode for a supercapacitor becomes limited. In this study, facile laser welding and surface modi?cation processes are demonstrated to overcome these limitations. First, a continuous wave laser beam is applied to the interface between the coated graphene and the underlying transparent polycarbonate substrate. This welding process signi?cantly improves their adhesion and enables excellent mechanical bendability. Second, surface modi?cation of graphene is achieved under ambient conditions by irradiating the graphene ?lm surface with a nanosecond pulsed laser. Sandwich-type supercapacitors are fabricated using these surface-modi?ed graphene electrodes with a PVA-H3PO4 electrolyte. The e?ect of the laser ?uence on the performance of the supercapacitor is investigated. At an optimal laser power, an areal capacitance of 4.7 mF/cm2 is achieved.
关键词： Laser transmission welding,Graphene,Flexible device,Supercapacitor,Pulsed laser
更新于2025-11-25 10:30:42
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Fabrication of bi-layer PMMA and aluminum 6061-T6 laminates by laser transmission welding: Performance prediction and optimization
摘要： Laser transmission welding can be effectively used in fabrication of laminated parts. In the present work an attempt was made to fabricate a polymeric laminate structure made of polymathic methacrylate (PMMA) and aluminum 6061-T6 by laser transmission welding process. A series of laser welding experiment has been carried out to analyze effect of laser power, welding speed, focal position and axial pressure on lap shear force and weld seam width. Response surface methodology including regression analysis, analysis of variances and desirability approach function has been utilized here to analyze the processing data. It is found from the results that focal position has greatest influence on both the lap shear force and weld bead width. Optimization is also carried out in two different criteria for achieving desired welding performance. The optimization results obtained by this approach are consistent well with the results measured through confirmatory experiments.
关键词： response surface methodology,polymer-metal lap joint,optimization,laser transmission welding
更新于2025-09-19 17:13:59
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Laser Welding of Carbon fibre filled Polytetrafluoroethylene
摘要： Herein, a method is described to weld polytetrafluoroethylene (PTFE), a non-melt processable thermoplast, using a thulium laser. Different settings for laser power and speed were used. The resulting mean lap shear strength per setting ranged from 0.081 N/mm2 to 0.297 N/mm2. The optimal setting was found to be 12 W irrespective of the welding speed applied. Micro-computed tomography (μ-CT) and optical microscopy was used to show that the welded pattern consisted of tunnel defects. As PTFE is known to be non-melt processable, a physico-chemical characterization was performed to examine the formation of degradation products. Differential scanning calorimetry (DSC) showed a reduction in molecular weight of the PTFE in the weld pattern after welding. Attenuated total reflectance infrared (ATR-IR) and nuclear magnetic resonance (NMR) spectroscopy using hexafluoroisopropanol (HFIP) did not indicate the presence of any new compounds in the respective spectra.
关键词： Laser transmission welding,Polytetrafluoroethylene (PTFE),Physico-chemical characterization,Degradation
更新于2025-09-19 17:13:59
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Improved stress-cracking resistance of laser welded amorphous thermoplastics by means of adapted wavelengths
摘要： Laser transmission welding is widely used for the creation of strong, hermetic and optically appealing joints between thermoplastic parts. Amorphous polymers like polycarbonate and poly(methyl methacrylate) offer excellent optical properties, making them suitable for this joining technique and especially attractive for lighting and decorative applications, for example in the automotive industry. However, the rapid and non-uniform temperature changes during the process can lead to residual stresses, which can impair weld strength and result in part failure due to environmental stress cracking. In this work it was found, that the application of 2 μm laser radiation can lead to reduced stress-cracking-susceptibility compared to conventional laser transmission welding with wavelengths of ~1 μm.
关键词： amorphous polymers,residual stresses,environmental stress cracking,laser transmission welding
更新于2025-09-16 10:30:52
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3-D FE heat transfer simulation of quasi-simultaneous laser transmission welding of thermoplastics
摘要： Laser transmission welding of thermoplastics is a non-contact welding process for producing aesthetically and qualitatively high-grade joints with low thermal and mechanical stresses. In this research work, a three-dimensional heat transfer model is developed to simulate the quasi-simultaneous variant of laser transmission welding of thermoplastics. The thermal analysis is implemented to acquire the temperature history in this multi-pass welding process. The transient temperature field is computed using ANSYS? finite element code. The multi-pass movement of laser beam is realized by implementing a subroutine in ANSYS? Parametric Design Language (APDL). The effect of process variables namely laser power, welding speed, number of welding passes and line energy on temperature field during welding is investigated. The predicted outcomes of the temperature profiles, weld pool and time–temperature history are useful for optimizing the process parameters in the quasi-simultaneous laser transmission welding process.
关键词： Thermal analysis,Laser transmission welding,Thermoplastics,Quasi-simultaneous welding,Finite element model
更新于2025-09-12 10:27:22
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Laser transmission welding of PMMA using IR semiconductor laser complemented by the Taguchi method and grey relational analysis
摘要： Laser transmission welding involves localized heating and non-contact techniques at the interface of two polymer pieces to be joined. The welding quality is very sensitive to speed welding, thickness and welding line width and depth. This work presents the laser transmission welding of Poly(Methyl Meta acrylate) PMMA polymer transparent and oblique slabs. A semiconductor laser with 808 nm wavelength, 2 W output power and a 2 mm beam diameter was used. Three different transparent slabs with dimensions 40 (cid:1) 60 mm and thickness (2.6, 3.7, 4.3 mm) were ?xed tightly onto oblique slab (dark color). Three different selected speeds (44, 113, 150 mm/min) of the welding process were applied to the prepared samples. Results indicate the welding line width and depth were inversely proportional to the welding speed while the transparent slab thickness have little effect. Nine experiments were performed for the three different thickness at different speeds. Taguchi method and grey relational analysis were used to determine the optimum values for welding speed, width, depth and thickness during these nine experiments. The results exhibit good agreement with those of the Taguchi method and grey relational analysis.
关键词： Polymer,Taguchi method,Grey relational analysis,Semiconductor laser,Laser transmission welding
更新于2025-09-12 10:27:22
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Optical coherence tomography for laser transmission joining processes in polymers and semiconductors
摘要： Laser transmission welding applications become wide spread technology in joining transparent and turbid materials. The requirement of higher throughputs and lesser rejects support the need of alternative methods to commonly used machine vision or temperature measurements. Optical coherence tomography delivers the opportunity to qualitatively assess transmission welding seems and welding spots even in three dimensions. Fourier Domain Mode Lock Lasers (FDMLs) used in OCT enable high throughput by high sweep rates. Preliminary results of OCT used for qualitatively assessment of laser transmission welded polymers and fiber reinforced plastics are shown as well as first approaches of using OCT in a silicon chip bonding process.
关键词： OCT,laser transmission welding,quality control
更新于2025-09-12 10:27:22
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Laser transmission welding of polymers – Irradiation strategies for strongly scattering materials
摘要： In laser transmission welding of thermoplastics the optical properties of the transparent part have great influence on the weld seam quality. Especially scattering, for example at crystalline structures or additives, can significantly affect the intensity distribution of the radiation in the joining zone. Since scattering is a strongly wavelength dependent process the right choice of the laser wavelength can enable laser transmission welding even for challenging materials. It is shown that the necessary optical material properties needed to assess the weldability of scattering materials can be directly obtained from NIR-spectroscopy.
关键词： thermoplastics,spectroscopy,optical properties,laser transmission welding,scattering
更新于2025-09-12 10:27:22