Papers by Keyword: ER

Abstract: The present work reviews the results of the photoluminescence study of erbium-doped ZnO nanostructures synthesized by physical and chemical methods. ZnO is a semiconductor compound composed of zinc and oxygen atoms. It possesses a wide bandgap (3.37 eV) and is optically and electrically active. When ZnO is synthesized in the form of nanostructures, such as nanoparticles, nanowires, nanorods, nanotubes, or nanosheets, it exhibits enhanced properties compared to its bulk counterpart due to quantum confinement effects and a high surface-to-volume ratio. By controlling different parameters in the growth processes of erbium-doped ZnO nanostructures, materials can be synthesized for different applications such as sensors, optoelectronics, and energy harvesting.

Abstract: In this paper, an Al-Zn-Mg-Cu alloy with a small amount of Er and Zr added was used as the research object. The homogenization annealing was carried out, and the 7N01 aluminum alloy was used at 300 °C, 350 °C, 400 °C, 450 °C and 0.1 s^-1, 1 s^-1, 10 s^-1 deformation conditions by Gleeble-3500 thermal simulator. Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Electron Backscatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM) were used for microstructure analysis. The results show that the stress-strain curve of with Er 7N01 aluminum alloy can be divided into micro-strain stage, uniform deformation stage and steady-state flow stage during the thermal compression process. The flow stress of 7N01 aluminum alloy achieved peaks at the initial stage of strain, and then increased with the increase of strain rate and the decrease of deformation temperature. With the increase of deformation temperature and the decrease of deformation rate, the recrystallization process was significantly increased.

Abstract: Erbium is an effective micro-alloying element in aluminum alloys and has been investigated intensively. Similar with the addition of Sc in aluminum alloys, nanosized L1₂-ordered Al₃Er precipitates were formed coherently with the matrix in Er-containing micro-alloying aluminum alloys. Further, in the case of the addition of both Er and Zr, core-shell-structured Al₃(Zr_xEr_1−x) precipitates, instead of Al₃Er, were observed in a fine dispersion. Those thermally-stable precipitates can refine the grain size, minimize the segregation, homogenize the microstructure, enhance the strength, hinder the recrystallization, and thus improve the comprehensive performance of the aluminum alloys. This paper presents the effect of Er on the microstructure, mechanical properties and thermal stability of aluminum alloys. The research of some typical commercial aluminum alloys containing Er, is also reviewed here.

Abstract: It has particular heat-resistant property and conductivity of high-conductivity heat-resistant Aluminium alloys, which would be wildly applied in transmission and transformation flied. Al-Er-Zr alloys containing different content of Zr were prepared. The effect of Zr on microstructure of heat-resistance Aluminum alloy were studied by using of STEM, and thermodynamic behavior of Zr in Aluminium alloy was analyzed based on the theory of alloy phase formation. The results showed that the effect of Zr content on the grain size of heat-resistant aluminum alloy was remarkable, and the conductivity of heat-resistance Aluminum alloy was influenced.

Abstract: Integration of smart materials such as field-responsive fluid, i.e. Electro-rheological (ER) , magneto-rheological (MR) and shear thickening fluids (STFs), into armor protective materials, may probably solve the problem between its portability and protective performance. The wide applications of three fluids are described in brief in this paper, and research developments (especially STFs’ in detail) of armor protective materials strengthened by utilizing three fluids or chemical reaction material are summarized. Analysises are made of the questions faced by these composites researches. The foreground is talked about in the end.

Abstract: The effect of heat treatment on the long-term corrosion resistance of Er containing 5083 aluminum alloy was studied using the micro-hardness test and mass loss test. The microstructure was analyzed by TEM. To maintain the strength, the annealing temperature was selected to be 100-230°C below the recrystallization onset temperature determined by the micro-hardness test. The plot of the annealing temperature versus the Intergranular Corrosion (IGC) initial time, which is determined by the Nitric Acid Mass Loss Test, showed a C-curve. The shortest IGC initial time (~1h) happened at 175°C, the nose temperature of the C-curve. When annealed at 125-200°C, the samples were IGC sensitive with the initial time less than 3h. The entirely IGC resistant (stabilized) samples were obtained when annealed at 220-230°C. The 175°C sensitized treatment was performed on the 220°C-stabilized samples, which showed that the 3-12h stabilization could significantly improve the resistance for long-term corrosion. TEM results showed that, for the IGC sensitive samples, β phases (Al₃Mg₂) grew along the grain boundary continuously, while for the stabilized samples, they were isolated on triangle grain boundary and phase boundary.

Abstract: Er³⁺/Yb³⁺ co-doped transparent phosphate glass ceramics were fabricated and characterized optically. The formation of nanocrystals is confirmed by x-ray diffraction. Stark split near infrared emission peaks of Er³⁺ have been observed in the glass ceramics, and the effective bandwidth increases with increasing annealing temperature. Upconversion emissions of Er³⁺ in the glass ceramics under 975nm wavelength excitation, especially in the green wavelength region, are enhanced. The results can be attributed to the enhancement of ligand field due to incorporation of Er³⁺ ions into the crystal lattices.

Abstract: In this paper, chip recycling technology combined with SIMA method which is called CR-SIMA method was adopted to prepare semi-solid billets. AZ91D magnesium alloy was refined by Er and its microstructural evolution was investigated during semi-solid isothermal treatment. The results show that Er can improve the feature of cast structure and decrease the grain size. Moreover, the γ-Mg₁₇Al₁₂ phase is well refined and disperses in the α-Mg matrix. A semisolid microstructure with small and spheroidal primary particles can be obtained after partially remelting. With increasing heating temperature, the dissolution of eutectic Mg₁₇Al₁₂ phase first took place, resulting in the primary dendritic grains coarsening into interconnected non-dendritic grains. With heating continuously, the residual interdendritic γ-Mg₁₇Al₁₂ at the edges of the primary grains melted in succession and the primary grains separated into small polygon grains. During the semi-solid isothermal treatment, the amount of liquid increased until the solid-liquid system reached its equilibrium state. At the same time, owing to the decreasing of interfacial energy, the grains gradually spheroidized and began to grow with a further increasing of the holding time.

Abstract: A series of experiments are conducted to polish glass-ceramic by a circular-type integrated electrode tool in the electrorheological(ER) fluid-assisted polishing process. In this study, the microstructure of fibrous columns formed by particles perpendicular to the electrodes is observed when the electrical field is applied. The mass of ER polishing fluid gathered on the tip of tool electrode and the normal pressure in polishing area are measured by the dynamometer. The influential regularities of the concentrations of abrasive particles, the applied voltage, the spindle rotational speed, mixing ratio for abrasives and the gap between tool electrode and workpiece on the surface roughness are obtained by experiments.

Abstract: The normal pressure in polishing area is investigated in electrorheological (ER) fluid-assisted polishing process. Under the influence of the non-uniform electric field, the dielectric particles in the ER polishing fluid are polarized to form the rigid core attached to the tool electrode due to the ER effect. In this work, the rigid core generated by the gathered mass of ER polishing fluid on the tip of tool electrode with the applied electric field is analyzed. The material is removed by abrasive particles under the effect of normal pressure and velocity. Based on the theory of hydrodynamic lubrication, a mathematical model taking into account the normal pressure is derived. Further experiments about the normal pressure experiments changing with the applied voltage, spindle rotational speed and working gap are conducted and the experimental results are compared with the theoretical results, which confirm the validity of the presented model