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Analysis of the effect of the thermomechanical processing on the laser weld joint of aluminum alloys of Al-Mg-Li and Al-Cu-Li
摘要： The paper presents the experimental investigation of the laser welding of high-strength aluminum-lithium alloys of Al-Cu-Li and Al-Mg-Li system followed by the thermal processing, aimed to the production of a high-strength weld joint. It is founded that the thermal processing (quenching, artificial ageing) of the welded joint increases its strength, however the variation of the microstructure and phase composition is different for the two systems of the alloys. The thermal processing permits getting the tensile strength of the welded sample of 0.9 of the basic alloy strength for Al-Cu-Li and 0.95 for Al-Mg-Li.
关键词： microstructure,thermal processing,CO2 laser,laser welding,phase composition
更新于2025-09-12 10:27:22
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Characterization of the fast ionization wave induced by a CO <sub/>2</sub> laser pulse in argon
摘要： Fast ionization wave (FIW), a postbreakdown phenomenon of laser-induced plasma, is observed for a laser intensity of 1011–1013 W/m2 using the CO2 laser pulse in the atmospheric pressure condition. FIW is distinguishable as “overdriven detonation” according to Raizer’s Chapmann-Jouguet detonation theory because FIW is known as the type of laser-absorption wave that has a higher propagation velocity than the laser-supported detonation wave (LSDW). Some reports have described the expansion of FIW using a solid-state laser. Nevertheless, the threshold phenomena between FIW and LSDW are not fundamentally understood. This study used the high-speed visualization and optical emission spectroscopy to investigate the transition of the laser-absorption wave in argon gaseous form. To elucidate the physics of the transition threshold, a 5 J CO2 pulse laser, an Echelle spectrometer, and an intensi?ed CCD camera are used for the quantitative investigation of the plasma temperature and density. Results demonstrate that the FIW front had an electron temperature of 0.7 eV and an electron number density of 2.5 × 1023 m?3. At the FIW–LSDW transition, the electron temperature increased by 1 eV, and the density decreased by 2.2 × 1023 m?3. Besides, the transition threshold and the existence of local-thermodynamic equilibrium were evaluated based on the electron temperature, and the density was obtained from the spectroscopic experiments.
关键词： plasma temperature,optical emission spectroscopy,fast ionization wave,plasma density,CO2 laser,laser-induced plasma
更新于2025-09-12 10:27:22
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Optimization Of Process Mean Setting For CO2Laser Welding Process For Alloy Steel Automotive Gears With Application Of Taguchi Loss Function And Fraction Defective Method
摘要： In the present research work, authors suggest a fundamental approach for estimation of optimum process mean setting through the trade-off between cost of manufacturing (power cost) and internal quality loss to the manufacturer for CO2 laser welding process which is successfully applied for joining automotive gears of 16MnCr5 alloy steel and the process mean has been optimized subsequently. Two different approaches viz., the application of Taguchi quadratic loss function and fraction defective method have been used and compared for assessment of internal quality loss to the manufacturer. It is concluded that this approach can be applicable for any manufacturing situation.
关键词： Welding Speed,Laser Power,Alloy Steel 16Mn Cr5,Power cost,Weld Depth,CO2 Laser,Taguchi quality Loss,Fraction Defective
更新于2025-09-12 10:27:22
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An original LIBS system based on TEA CO2 laser as a tool for determination of glass surface hardness
摘要： This study was carried out to examine the applicability of original laser-induced breakdown spectroscopy (LIBS) setup for determination of the surface hardness of lead glass as a function of its chemical composition. For this purpose, a set of five lead glass samples with different amount of ZrO2 was prepared. The LIBS measurements were carried out using TEA CO2 laser in the air at atmospheric pressure and without sample preparation. A ratio of the intensity between the Zr(II) 355.66 nm and Zr(I) 360.12 nm emission lines has been used to examine the hardness of the material. In addition, the surface hardness of glass samples was determined by Vickers’s indentation tests. Obtained results indicate a linear relationship of the measurements of hardness in glass samples between the LIBS and Vickers method. To show that LIBS based on TEA CO2 laser is an almost nondestructive technique, profilometric surface analysis was used. The proposed LIBS system is suitable not only for a spectrochemical analysis but also as an easy to use and cost-effective way to measure the surface hardness for all types and shapes of glass samples which are in some cases difficult to examine by standard Vicker’s method.
关键词： surface hardness,lead glass,ZrO2,LIBS,TEA CO2 laser
更新于2025-09-12 10:27:22
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Fabrication of Polypropylene Nanofibers from Polypropylene/Polyvinyl Butyral Blend Films Using Laser‐Assisted Melt‐Electrospinning
摘要： Polypropylene (PP) nano?bers, a few hundred nanometers in diameter, are of immense importance in the ?ber industry. This article reports the fabrication of delicate PP nano?bers. Polyvinyl butyral (PVB) was added to PP as a blend component, and a nozzle-free melt-electrospinning system with a line-like CO2 laser melting device was used to manufacture PP nano?bers. We investigated the effect of PVB ratio on ?ber diameter. The addition of PVB was found to be potentially very bene?cial in PP/PVB blends, resulting in improved PP crystallinity and a steady decrease of ?ber diameter with high productivity. The reduction of ?ber diameter was attributed to the decline of viscosity, increase of surface adhesion properties, and polarity of blends due to the inclusion of PVB. To produce PP nano?ber, the PVB was removed from PP/PVB blend ?bers with an ethanol treatment. A drastic drop of PP ?ber diameter followed by ?ber splitting was observed after PVB removal. We obtained PP nano?bers with a diameter as low as 181 (cid:1) 105 nm from the blend ?ber with 90% PVB. Infrared spectroscopy of ?bers demonstrated that PP ?bers from pure polymer and blends showed the same characteristic peaks.
关键词： Polyvinyl butyral,ethanol treatment,Polypropylene,melt-electrospinning,CO2 laser,nano?bers
更新于2025-09-12 10:27:22
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The Combination of Photodynamic Therapy and Fractional CO2 Laser for Oral Leukoplakia: Case Series
摘要： Oral leukoplakia (OL), a predominantly white change to the oral mucosa, is the most common potentially malignant lesion. Elimination of this condition, especially the high risk OL, is advisable, even necessary as an attempt to avoid malignant transformation. Here we presented three cases of OL successfully treated by photodynamic therapy (PDT) following pretreatment with CO2 laser. After a series of one to three sessions the patients were monitored for 12 months. All the lesions showed completed remission, but one recurred during follow-up. Side effects included mild edema, erosion and burning sensation. No severe side effects were observed. In summary, the combination of PDT and CO2 laser is safe and effective in the treatment of OL, which is a promising treatment.
关键词： CO2 Laser,Oral Leukoplakia,Photodynamic Therapy
更新于2025-09-12 10:27:22
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Influence of polymer molecular weight on the properties of in situ synthesized silver–methylcellulose nanocomposite films with a CO2 laser
摘要： We investigate the in?uence of polymer molecular weight on the properties of silver–methylcellulose (Ag–MC) nanocomposite ?lms synthesized by the irradiation of a CO2 laser. Although the reduction power of MC with a smaller molecular weight turns out to be stronger than that with a larger molecular weight in the solution phase, we do not see such a clear difference when MC is in the matrix phase. For the 30 s irradiation at the laser power of 0.8 W, the size of Ag nanoparticles (NPs) in the two types of MC matrix is similar, and it is about 30 nm. However, for the longer irradiation time at the same laser power, aggregation of Ag NPs set in, and it is more serious for the Ag–MC ?lm with MC of larger molecular weight. We also carry out the antibacterial test with the Ag–MC ?lms, and ?nd that the Ag–MC ?lm synthesized at the lower laser power and shorter irradiation time generally exhibits a stronger antibacterial effect.
关键词： antibacterial effect,polymer molecular weight,CO2 laser,silver–methylcellulose nanocomposite
更新于2025-09-12 10:27:22
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Experimental Investigations To Optimize Process Parameters For CO2 Laser Welded Alloy Steel Automotive Gears
摘要： In the present research, CO2 laser welding process is successfully applied and optimized for joining automotive gears of 16MnCr5 Alloy Steel. The combinations of laser power and speed of welding are optimized with the aim to produce welded joint in automotive gear-synchro assembly with required weld depth, weld width and weld strength. Taguchi method of “Design of Experiments (DOE)” and ANOVA have been used as statistical design tools and techniques for optimizing the selected welding process parameters. Further, variation transmission analysis technique has also been applied to determine the range of input variable that gives least variability of the output. The result of this research effort indicates that the developed models are capable of predicting the responses with negligible errors.
关键词： ANOVA,Taguchi Method,Alloy Steel 16MnCr5,Variability Transmission,DOE,CO2 LASER
更新于2025-09-12 10:27:22
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Nanoparticle-Mediated Cavitation via CO2 Laser Impacting on Water: Concentration Effect, Temperature Visualization, and Core-Shell Structures
摘要： By taking advantage of seeded polymer nanoparticles and strong photo energy absorption, we report co2 laser impacting on water to produce cavitation at the air/water interface. Using a high-speed camera, three regimes (no cavitation, cavitation, and pseudo-cavitation) are identified within a broad range of nanoparticles concentration and size. The underlying correlation among cavitation, nanoparticles and temperature is revealed by the direct observation of spatiotemporal evolution of temperature using a thermal cameral. These findings indicate that nanoparticles not only act as preexisted nuclei to promote nucleation for cavitation, but also likely affect temperature to change the nucleation rate as well. Moreover, by exploiting a compound hexane/water interface, a novel core-shell cavitation is demonstrated. This approach might be utilized to attain and control cavitations by choosing nanoparticles and designing interfaces while operating at a lower laser intensity, for versatile technological applications in material science and medical surgery.
关键词： temperature visualization,nanoparticle,CO2 laser,cavitation,core-shell structures
更新于2025-09-12 10:27:22
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Use of Intraoperative CO2 Laser for the Resection of a Ventral Intradural Extramedullary Cervical Spinal Tumor: 2-Dimensional Operative Video
摘要： Ventral spinal tumors are surgically challenging because the tumor resection should minimize spinal cord and nerve root manipulation to minimize morbidity, while providing access to a complete tumor resection. The CO2 laser has been useful in resection of central nervous system tumors, but little is described about the method used to resect spinal tumors. This video demonstrates the removal of a ventral cervical spinal meningioma using the CO2 laser. A 62-yr-old man presented with progressive paresthesias, gait instability, and urinary frequency. A 1-cm intradural extramedullary mass at C5 showed severe spinal cord compression. Patient consent was obtained prior to performing the procedure. A posterior lateral approach is shown, with a bone removal corridor created at C5 for accessing the tumor ventrally. A right-sided facetectomy and pediculectomy at C5 were performed being flush with the posterior vertebral body. A dural opening positioned laterally provided a working corridor between C5 and C6 nerve rootlets. Lateral portions of tumor were excised in wedge-shaped slices starting laterally and working medially. These slices created a successive and enlarging space to safely allow piecemeal tumor dissection and removal, while limiting retraction upon the spinal cord. The CO2 laser was used to cauterize the tumor capsule, create wedge resections of tumor, and coagulate the final dural attachment. The pathology was a meningioma WHO Grade I. The patient did well, with resolution of parasthesias and ataxia. The CO2 laser technique allowed for limited spinal cord retraction throughout the tumor resection and gross total resection of the tumor was achieved.
关键词： Cervical spinal tumor,Intramural extramedullary,CO2 Laser,Meningioma
更新于2025-09-12 10:27:22