Frontiers of Materials, Chemical and Metallurgical Technologies

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Authors: Xian Yan Zhou, Mi Mi Chen, Chang Wei Su, Yan Xia, Xiang Zhong Huang, Ying Jie Zhang, Jun Ming Guo
Abstract: LiMn2O4 cathode materials were successfully prepared by solid-state combustion synthesis with the lithium carbonate and the manganese carbonate as raw materials and the citric acid as fuel. The effect of citric acid on composition, microstructure and electrochemical properties of LiMn2O4 cathode materials was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV) and galvanostatic charge-discharge test. The results indicated that a pure phase of LiMn2O4 was prepared at the product with 5 wt% citric acid. However, an impure phase of Mn3O4 was found at other products. The crystal size distribution was more uniform at the higher content of citric acid. The products with 5 wt% and 10 wt% citric acid, the cubic structure morphologies of which were more prominent, and the capacities of which were higher than that of bare LiMn2O4 product. Their initial discharge specific capacities were 119.6 mAh•g-1 and 114.0 mAh•g-1, and their capacity retention ratios after 40 cycles were 85.0% and 87.7%, respectively.
353
Authors: Tao Ding, Guang Xiong Chen, Qiu Dong He, Wen Jing Xuan
Abstract: Influence of the support stiffness and contact force on friction and wear behaviors of stainless steel rubbing against copper-impregnated metalized carbon under electric current was researched on an improved friction and wear test machine. The result indicates that the support stiffness and the contact force significantly affect the friction coefficient of contact pairs, wear and surface roughness of pin samples. The appropriated support stiffness and contact force can effectively reduce friction material wear of contact couple.
359
Authors: Yan Long, Yu Lan Gong, Shi Ying Ren, Xiao Xiang Wu, Xin Kun Zhu
Abstract: Abstract. The mechanical properties and microstructure of an ultrafine-grained Cu–Al alloy before and after annealing are investigated. Ultrafine-grained Cu–Al alloy samples are processed by means of rolling at ambient temperature and rolling reduction exceeds 90%. It is found that the strength of ultrafine-grained Cu–Al alloy increased rather than decreased after annealing for 1 h in the temperature range between150°Cand 300°C.Based on the microstructures observation of samples, it can be known that both the grain size and dislocation density have main effects on hardening of ultrafine-grained Cu–Al alloy which result from annealing. These investigations showed that the annealing hardening effect can be explained by the change of dislocation density and twin density.
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Authors: Xiao Song Zhou, Xiao Yan Zhang, De Feng Wu
Abstract: Ceramic coatings were fabricated on a new casting aluminum alloy during micro-arc oxidation by mixing nano-SiO2 into the phosphate electrolyte. The effects of nano-SiO2 in electrolyte on thickness, hardness and microstructure of the ceramic coatings were analyzed. The results show that nano-SiO2 is deposited on the surface layer of the ceramic coatings in micro-arc oxidation process. The compactness of the coatings is thus improved. Both the thickness and hardness of the ceramic coatings increase a lot. The optimal addition amount of nano-SiO2 in the electrolyte is 3g/L
368
Authors: Long Li
Abstract: Using ladle slag, ferrovanadium smelting slag as well as metallurgical auxiliary materials as raw materials, the converter slag with SiO2 content of 11.3% to 2.8%, Al2O3 content of 3.3% to 19.4% were prepared. The melting characteristics of slag were measured, at 1600 °C both dephosphorization and desulfurization tests of slag were conducted in atmosphere furnace. The research results show that the melting properties of slag are improved with the reduce of SiO2 content and the increase of Al2O3 content in slag, in favor of making high basicity slag in the early stages of BOF steelmaking. However, both dephosphorization and desulfurization of slag exhibit downward trend. The mechanism of SiO2 and Al2O3 contents of converter slag impact on metallurgical properties would be further discussed.
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Authors: Li Li, R.G. Hou, Z.W. Sima
Abstract: This paper presents an experimental investigation of the machining characteristics of IN718 nickel-based super alloy in wire electrical discharge machining (WEDM) process. During experiments, parameters of discharge current and pulse on time were changed to explore the effect on various aspects of the surface characteristic. Scanning electron microscopy (SEM), surface roughness and micro hardness tests were performed. Experimental results reveal that the surface roughness will increase with the increasing of current and pulse duration. Micro hardness tests show there is no hard phenomenon.
378
Authors: Zhong Hui Hou, Yin Zhang, Ying Cai, Feng Hu, Guo Fang Zhang, Xia Li
Abstract: The melt spinning technology was used to prepare the Mg2Ni0.6M0.4 (M=Cu, Co) hydrogen storage alloys in order to obtain a nanocrystalline and amorphous structure. The microstructures of the alloys were characterized by XRD, TEM. The effects of the melt spinning on the electrochemical and gaseous hydrogen storage capacities of the alloys were investigated. The results indicate that the as-spun (M=Cu) alloys hold an entire nanocrystalline structure even if a limited spinning rate is applied, while the as-spun (M=Co) alloys display a nanocrystalline and amorphous structure and the amount of the amorphous phase grows evidently with the rising of the spinning rate, suggesting that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. The melt spinning enhances the electrochemical and gaseous hydrogen storage capacities of the alloys dramatically. Simultaneously, it ameliorates the hydriding kinetics of the alloys substantially. As the spinning rate grows from 0 (As-cast was defined as the spinning rate of 0 m/s) to 30 m/s, the discharge capacity increases from 53.3 to 140.4 mAh/g for the (M=Cu) alloy and from 113.3% to 402.5% for the (M=Co) alloy; the gaseous hydrogen desorption capacity ( ) in 100 min augments from 2.29% to 2.87% for the (M=Cu) alloy and from 2.42% to 3.08% for the (M=Co) alloy.
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Authors: Zhi Qiang Luo, Xin Hong Chen, Li Li
Abstract: The industrial test of rutile TiO2 surface coated with Al2O3 and ZrO2 was completed using the TiO2 coated technology of low viscosity process at the TiO2 factory of PanGang group. The viscosity during the coating process, sample elements and elements distribution were respectively measured by viscometer, XRF and EDS. The results show that the viscosity of coating process is obviously lower than viscosity of existing coating technology, sample element distribution is more uniform on TiO2 surface, and the deposition rate of coating reagent is higher than it of sample using existing coating technology. The Al2O3 content fluctuation value of sample and sample using existing coating technology is respectively 0.56%, 1.19% on sample surface different points, and the Al2O3 deposition rate is 93%, 84.17%, respectively.
387
Authors: Wei Cong, En Xiang Han, Jiang Li
Abstract: TiO2 nanotube arrays were fabricated by anodic oxidation. It was studied that the influences of the parameters for the preparation of TiO2 nanotube arrays on the micrograph of the material, such as anodizing potential, annealing temperature. Then it is used in the dye sensitized solar cell (DSSC).The microstructures and morphologies of the TiO2 nanotubes were investigated by scanning electron microscopy (SEM) and x-ray diffraction (XRD). The results show that TiO2 nanotubes arrays were fabricated when anodizing voltage is 20V. The photoelectric conversion efficiency Subscript textof DSSC made by this structure is 1.53%, the open voltage is 0.734V, short-circuit current is 4.52mA, fill factor is 0.460.
391
Authors: Hui Ping Liu
Abstract: The influences of pH values and aluminum precursors of “glucose-water-aluminum salt” reaction system on the hydrothermal synthesis of mesoporous Al2O3 were investigated. With the aid of scanning electron microscopy (SEM), electron diffraction spectrum (EDS) and X-ray diffraction (XRD) characterizations, we found that, under hydrothermal treatment at 180 °C for 20 h, aluminum nitrate (Al(NO3)3) could be used as the precursor to synthesize the spherical flower-like Al2O3 by using the synthesis solutions with different pH values in a certain scope; using aluminum chloride (AlCl3) as precursor, we can only get a small amount of Al2O3 composed of micro-spheres and sheets; while adopting aluminum sulfate (Al2(SO4)3) as precursor, a small amount of cubic-shape aluminum sulfate crystal can be obtained.
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