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Synthesis, growth, optical, mechanical and dielectric studies on NLO active monometallic zinc iodate [Zn(IO3)2] crystal for frequency conversion
摘要： The monometallic single crystal of zinc iodate [Zn(IO3)2] was grown by slow cooling technique with the dimension up to 14 x 4 x 3 mm3 in the period of 35-45 days. Single crystal X-ray diffraction (XRD) analysis shows that the zinc iodate (ZI) crystal crystallizes in monoclinic crystal system with space group P21. The various functional groups of ZI were identified by FTIR analysis. The optical absorption of the grown crystal has been ascertained by UV-vis-NIR absorption studies. Second harmonic generation (SHG) efficiency of ZI is 2.75 times greater than that of KDP sample. The microhardness test of the grown crystal suggests that the crystal possesses relatively high mechanical strength. From the mechanical test certain mechanical parameters were determined. The dielectric behavior of the ZI crystal at different temperatures with varying frequencies shows the normal behavior activity of the grown crystal. The field dependent conductivity study was carried out.
关键词： Single crystal growth,Monometallic iodate,Dielectric studies,Microhardness,optical properties
更新于2025-09-10 09:29:36
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Nonvacuum Surfacing of Protective Coatings Using a Low-Energy Electron Beam
摘要： The results of electron-beam surfacing in air of protective coatings by a low-energy (120 keV) electron beam produced by an electron gun with a plasma emitter are presented. The gun is mounted on an industrial robotic manipulator KUKA, which allows the electron beam to be moved to the atmosphere along a given path without electromagnetic sweep. The combined (self-propagating high-temperature synthesis and electron-beam surfacing) method for obtaining coatings from reaction mixtures of TiO2 : 2.1C and TiO2 : 0.3Cr2O3 : 3.3С is implemented using this setup. The optimum composition of the reaction mixtures and the deposition regimes are determined by thermodynamic modeling using the TERRA program. The obtained coatings with a thickness of 120–200 μ m have a microhardness of 12 GPa. The coatings and the transition layer are established to have good heat resistance up to 900°C. Noticeable changes in the weight characteristics of coatings occur at above 1000°C.
关键词： electron beam surfacing at atmospheric pressure,microhardness,plasma emitter,electron beam,differential pumping system,carbide coatings,self-propagating high-temperature synthesis (SHS),electron gun,gas discharge
更新于2025-09-10 09:29:36
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Effect of heat input in pulsed Nd:YAG laser welding of titanium alloy (Ti6Al4V) on microstructure and mechanical properties
摘要： In the present investigation, titanium alloy Ti6Al4V of 1.4 mm thickness has been laser-welded in butt joint configuration using pulsed Nd:YAG laser system. The effects of heat input on weld bead shape, fusion zone width (top, middle, and bottom), heat-affected zone (HAZ) width (top, middle, and bottom), and fusion zone area have been studied. The microstructure and mechanical properties of laser-welded specimens at various heat inputs (43.7–103.5 J/mm) have also been investigated. Microstructures of the fusion zone, HAZ, and parent material have been compared at various heat inputs using optical microscope and field emission scanning electron microscope (FESEM). The mechanical properties such as microhardness and tensile strength of the welded joints at varying heat inputs have been studied. Tensile tests of the welded specimen and base metal have been conducted for analyzing ultimate tensile strength and percentage elongation. Surface topography of the tensile fractured specimen of the welded joints and base metal has been examined to analyze the ductile and brittle behavior. EDS analyses of base metal and fusion zone of the welded specimen have been studied. XRD of the as-received base metal and welded specimen have been measured in the range of 30 to 85° to study the crystallographic structure.
关键词： Ti6Al4V,Microstructure,Laser beam welding,Pulsed Nd:YAG laser,Microhardness,Porosity
更新于2025-09-04 15:30:14
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Study of the Effect of Ni additive in YBa2Cu3O7-δ Superconducting Composite Employing Ultrasonic Measurement
摘要： A series of superconducting composites (100-x) YBa2Cu3O7-δ + x Ni metal (x = 0, 1, 2.5, 5, 7.5, 10 and 15 wt.%) was prepared by the solid state reaction method. Density and molar volume were determined using the immersion method. X-Rays-Diffraction (XRD) and Scanning Electron Microscope (SEM) characterizations were terminated for structural and microstructural analysis. The results showed the presence of orthorhombic peaks of YBa2Cu3O7-δ (YBCO) in the whole composite samples with different lattice constants and how Ni addition affects the distortions in the orthorhombic unit cell of YBCO. A new technique has been used to measure the ultrasonic wave velocities, longitudinal (VL) and transverse or shear (VS), at 4 MHz ultrasonic frequency at room temperature. The mechanical parameters of the sintered superconductor samples including longitudinal modulus (L), shear modulus (G), Young’s modulus (Y), Poisson’s ratio (σ) and microhardness (H) were investigated from the view point of the porosity and the connectivity between the formed phases. Besides, the Debye temperature (?D) was also determined as a function of Ni additions. The elastic moduli, H and ?D have been improved up to 2.5 wt.% Ni, then a decrease in all data observed with further addition of Ni content. Quantitative analysis has been implemented to obtain more details about the structure of the composite samples, based on orthorhombic phases, the oriented grain size, the porosity and the agglomeration between grains.
关键词： Debye temperature,ultrasonic velocity,porosity,elastic moduli,microhardness
更新于2025-09-04 15:30:14