Papers by Keyword: Nd:YAG

Abstract: Abstrac. In the present work, gold nanoparticle (Au NPs) was synthesis by pulsed laser ablation (PLA) by using Q-switched, (Nd: YAG) (E=80mJ) (λ=532,1064nm) and Number of pulses (500)pulse of the gold metal target in deionized water. The optical properties were studied with a UV-vis spectrophotometer which tests the absorbance spectra and comparison of the generated nanoparticles solution. atomic force microscope (AFM) results show that the grain size increase by decreasing wavelength. The optical limiter of the resulting colloidal solution was studied.

Abstract: The study demonstrates laser welding of titanium alloy Ti6Al4V using middle range power Nd:YAG laser. Butt welding cross section views were analyzed to understand the influence of several scanning parameters to the welding beads shapes and material characteristic changes. Pulse laser was used to perform welding on titanium alloys Ti6Al4V. It was found out that fusion zone can appear in two layers which could give clues to internal temperature distribution during the scanning process.

Abstract: This paper reports an experimental study of laser welding on duplex stainless steel UNS S32205 employed in the oil and natural gas industries. A pulsed Nd:YAG laser was used to weld the specimens. Bead on plate condition was used. Scanning Electron and Optical microscopy was applied to measure and analyze the cross-sectional of the weld bead. From the experimental results, it was found that the shape and size of the welded spot depend not only on the laser energy, but also on the pulse duration and the focus position. Metallographic observations showed that the microstructure of the weld metal was characterized by large ferrite grains with intra and inter-granular austenite. Large voids delimited by the molten zone boundary were observed in weld beads with low pulse duration. The heat affected zone resulting from the welding is pretty much absent and no cracks were detected.

Abstract: 1.0at% Nd:YAG polycrystalline ceramics were sintered at 1420°C, 1500°C, 1600°C and 1730°C respectively by different heating rate (1°C/min and 5°C/min). The crystal structures were indexed by X-ray diffractometer (XRD). The microstructure and the grain size of the samples were characterized by scanning electron microscope (SEM). The optical transmittance spectra of the samples were measured using V-570 UV spectrophotometer. The sintering process of Nd:YAG ceramics and the effect of heating rate on the microstructure of samples have been investigated.

Abstract: Recently, laser welding has been in its infancy primarily used for exotic applications where no other welding process would be suitable. In recent era, industrial product parts and components are produced at a minute-scale for sustainable manufacturing, creating a growing need for micro-welding applications. In this regards, laser processing is more likely considered to be the method of choice as it allows precise heat control compared with other parallel methods. This paper presents the operating principle of laser device. In line with this it puts forth a review on advancement of Laser welding/Laser Micro-Welding. At the end, it concludes with description of benefits manufacturing engineers would obtain.

Abstract: 1.0at% Nd:YAG polycrystalline ceramics were fabricated with different sintering adds by solid-state reaction and vacuum sintering method. The optical transmittance spectra of the samples were measured using V-570 UV spectrophotometer. The microstructure and the grain size of the samples were characterized by Scanning electron microscope. It is found that the sample with 0.5wt% SiO₂ and 0.5wt% MgO had the best transmittance, the most densification and uniform grain size, and the grain size decreased with the increasing MgO. Effects of MgO on the microstructure of YAG and its action mechanism have been investigated.

Abstract: A graphene-PVA film is fabricated by using polyvinyl alcohol(PVA), which provides excellent mechanical property and easy operation. Based on the numerous advantages of graphene in optical and mechanical characteristics,Graphene was used as absorber with passively Q-switched Nd:YAG solid laser in our experiment. Furthermore, there are no changes in the structure and characteristics of graphene. Inserting our graphene-PVA SA mirror to the Nd: YAG laser, we ultimately get that the single pulse energy is about 7.68μJ, and that the shortest pulse width is about 640ns. The experiment results prove that our graphene-PVA SA mirror is feasible and suitable for Q-switched lasers.

Abstract: Yttrium Aluminum Garnet (Nd:YAG) transparent ceramic doped with Nd have predominantly chemical stability, excellent optical quality and high temperature stability, it is becomeing a substitute for single crystal, had already become new generation laser material, have important strategic sense in the laser and the superelevation powders laser system. Al(NO₃)₃·9H₂O, Y₂O₃, Nd₂O₃,(NH₄)₂SO₄ and NH₄HCO₃ are raw material, TEOS is additive and ethylene glycol(EG). Nd:YAG precursor powders witch is Homogeneously dispersed, little agglomerated, pure YAG phase, different Nd³⁺ doped density were prepared by the co-precipitation method. The Nd:YAG ceramic powders were characterized by TG-DTA, XRD, FT-IR.

Abstract: Millimeter-wave sintering of ceramic laser host materials has been under investigation for high-energy laser (HEL) applications. Advantages of polycrystalline, compared to single-crystal, laser host materials include lower processing temperature, higher gain from higher dopant concentration, cheaper fabrication, and larger devices. We are currently investigating the solid-state reactive sintering of neodymium-doped yttrium aluminum garnet (Nd:YAG) using a high power millimeter-wave beam as the heat source. The 83 GHz beam is generated in the Naval Research Laboratory (NRL) High Frequency Materials Processing Facility that is powered by a 15 kW, CW, 83 GHz GYCOM gyrotron. The starting powder is a mixture of commercially available alumina, yttria, and neodymia powders. Near transparency and over 99% theoretical density have been achieved with grain sizes of 5 to 10 µm. The fluorescence lifetime of the Nd+3 1.06 µm lasing transition was measured to be about 200 µs, in good agreement with other work. SEM studies of the sintered microstructure show residual porosity caused by trapped pores that must be eliminated to produce fully transparent material.

Abstract: Pure-phase 2at% Nd:YAG powder was synthesized by alcohol-water co-precipitation method. 2at% Nd:YAG ceramics were sintered at 1780 °C for 10 h under vacuum using the powder. Sintering ability of the powder was studied by comparing the results of alcohol-water solvent with those of distilled water solvent. The effects of different volume ratios of alcohol to water (R) on transparent ceramics have been also studied. Transparent ceramics having a transmittance of 40% in the visible wavelength have been sintered without sintering additive using the powder (R=0.8), which is much better than ceramics (16%) prepared using the powder derived from distilled water solvent under the same sintering conditions. In addition, the different R does not have much influence on the transmittance of ceramics in the present work. Compared with the results of distilled water solvent, the powders, using alcohol-water mixtures with different R as solvent, are more beneficial to the sintering of high transparent ceramics.