Frontiers of Materials, Chemical and Metallurgical Technologies

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Authors: Jian Hua Du, Yi Xu, Yuan Yuan Li
Abstract: Cu-based nanometer composites with ω(n-SiO2)=1.0 % nano-SiO2 were prepared through ball milling and powder metallurgy technology. The friction and wear performance of the composites was investigated by ball-disk friction and wear tester. The microstructure and wear morphology were studied by drainage and field scanning electronic microscope (FSEM), respectively. The results indicate that ball milling can improve the spatial distribution of nano-SiO2 in the copper matrix. With the ball milling time increasing, the dynamic friction coefficient and wear rate of the composites decrease firstly and then increase. The composite milled 10 h has the lower friction coefficient and wear rate, and its main mechanism is abrasive wear.
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Authors: Qiao Yun Zhang, Ze Min Chen, Meng Long Qi
Abstract: Copper tube was the air conditioner heat dissipation commonly used material, their hydrophilic and corrosion resistance was great significance to improve the air conditioner heat dissipation effect and the service life. Hydrophilic film was prepared with key components of silica sol and acrylic. The experiment process mainly investigated the effect of soaking time, temperature, pH value, silica sol concentration and the acrylate concentration on the hydrophilic film. Hydrophilic property and corrosion resistance were tested. The best technological conditions were as follows: at room temperature, 5min, the silica sol concentration of 60%, the acrylate concentration of 1%, pH = 13. The experimental results show that hydrophilic angle was 13°, and corrosion resistance as good as the deactivation film.
491
Authors: Fei Gang Yuan, Bu Ming Chen, Feng Bang Shi, Zhong Cheng Guo, Rui Dong Xu
Abstract: The anodic coating of α-PbO2-Co3O4-CeO2 on stainless steel was prepared by DC deposition in this paper. The effect of different conditions and solid particles on the binding, appearance and deposition rate of the composite was researched. The optimum conditions for electrode preparations were obtained as follows: the current density 1.5 A/dm2, electroplating time 2 h, temperature 40 °C, Co3O4 30 g/L and CeO2 15 g/L. On this condition, the α-PbO2-5.43wt% Co3O4-4.64wt%CeO2 composite coating can be obtained. SEM and linear sweep voltammeter were used for the analysis of the surface structure and oxygen evolution potential. The results showed that the doping particles can not only improve electrode surface area but also reduce the granularity of pellet. The α-PbO2-5.43wt%Co3O4-4.64wt%CeO2 electrode has a lower oxygen evolution potential and higher electrocatalytic activity than pure α-PbO2 electrode.
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Authors: Meng Meng Lin, Yong Xie, Lei Du, Feng Yuan Zou
Abstract: This paper studies the conductivity of plain woven fabric of embedded silver-plated fibers of different twists. Five samples of different numbers of twists are tested under weft tensile. The results are the following: during the process of elongation, the resistance of fabric is bigger than the initial resistance, the rate of resistance change shows positive relationship with strain and presents a rising tendency generally; when the number of twists is 300 T/m, the rate of resistance change is bigger than other four fabrics under the same strain, the stability of changes of relative resistance of fabric is better than others; the rate of resistance change of fabric changes stably in the range of 0%~15% elongation.
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Authors: Yan Qing Wang, Zhao Gang Liu, Ben Shuang Sun, Dong Xin Wang
Abstract: Due to low-density, higher elevated temperature strength and good oxidation resistance; the Nb-Ti-Cr-Al alloy was estimated to become a new kind of material used at elevated temperature of next generation. Therefore, it was widely studied by western developed country, but there are still many questions unsolved in this area. In this article, several kinds of Nb-Ti-Cr-Al alloys of different compositions were prepared by arc melting, and analyzed by metallographic method, XRD, SEM and EDS. The results indicated, in Nb-40Ti-15Al alloy, the solidified Structure was typical small equiaxed grains, columnar crystals and common equiaxed crystals. And in Nb-40Ti-10Cr alloy, there is a serious coring segregation of Cr element; it can induce intergranular fracture of ingot. As the content of Cr element increased, constitutional supercooling occurred in solidification process, and the microstruture changed from straight crystal boundary to dendrite, such as Nb-40Ti-20Cr alloy. As for Nb-40Ti-10Cr-10Al alloy, the addition of Al and Cr lead to a great number of sub boundary and precipitated phase, and the microsegregation in alloy are also reduced to a certain degree. To sum up, the content level of Cr and Al is essential to both the microstructure and mechanical performances of Nb-Ti based alloys.
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Authors: Jin He Jiang
Abstract: A spinel-type metal compound [Mg0.75Ti1.125O3], was prepared by a coprecipitation/ thermal crystallization method. The extraction/insertion reaction with this material was investigation by X-ray, saturation capacity of exchange, and Kd measurement. The acid treatments of Mg0.75Ti1.125O3 caused Mg2+ extractions of more than 71%, while the dissolutions of Ti4+ were less than 7.2%. The experimental results have proved that the acid-treated sample has a capacity of exchange 7.5mmol•g-1 for Li+ in the solution. It had a memorial ion-sieve property for Li+.
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Authors: Hong Zhu, Zhi Jun Guo, Wein Duo Yang, Wein Feng Chang
Abstract: This study investigated the structure, microstructure and optical properties of the highly-oriented lead barium titanate (Pb1-xBaxTiO3, PBT) thin films prepared on MgO (100) substrate by a nonaqueous sol-gel process. The film precursor was synthesized by the modified sol-gel processing from lead acetate, barium acetate, and titanium isopropoxide, acetylacetone as chelating agent, and ethylene glycol as solvent. This stable precursor was formed by acetylacetone chelating with titanium isopropoxide and then mixing the solution of the acetates. The spin-coating technique was used to deposit the PBT films on MgO (100) substrate with different barium contents and various spin-coating numbers, respectively. X-ray diffraction was employed to study the crystal structure of the thin film and field emission scanning electron microscopy was used to characterize the microstructure of the films. Optical properties of the thin films were investigated by Ultraviolet-visible spectrophotometer. All films exhibited a (100) preferred orientation, especially the PB0.5T (3-coating layers) thin film. In the optical properties, the adsorption wavelength shifted to the ultraviolet region with increasing barium.
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Authors: Rui Ming Yin, Fu Bao Ji, Qing Lin Hou, Li Jing, Lin Zhang Chen
Abstract: Fe-Mo/Si3N4 cermet powers are prepared by heterogeneous precipitation-thermal reduction process and sintered on normal pressure with Y2O3-MgO additives.The effect of sintering temperature on the phase composition, microstructure and mechanical properties are discussed. Result of study indicates: the rise of sintering temperature is beneficial to retention the metal phase and the generation of β-Si3N4 whisker. At the temperature of 1650°C, Y-Mg-Si-O-N glass phase is generated, At the temperature of 1700°C, whiskers-like β-Si3N4, good wettability phases on Si3N4 surface, and high toughness Fe phase appeared in Fe-Mo/Si3N4 cermets. It can effectively better the microstructures of Fe-Mo/Si3N4 cermets, and contribute to improve the material mechanical perperties. When the temperature rise to 1750°C, the maximum particle MoSi2 can destroy the microscopic structure, and decreases the density and mechanical properties of ceramics fast. The optimum sintering temperature is therefore about 1700°C.
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Authors: Jia Feng Zhang, Bao Zhang, Xue Yi Guo, He Zhang Chen, Jian Long Wang, Chao Shen, Jun Chao Zheng
Abstract: The LiFe0.98Mn0.02PO4/C was synthesized by spray-drying and low temperature reduction route using FePO4•2H2O as precursor, which was prepared by a simple co-precipitation method. The LiFe0.98Mn0.02PO4/C sample was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and electrochemical measurements. The XRD analysis and SEM images show that sample has the good ordered structure and spherical particle. The charge-discharge tests demonstrate that the powder has the better electrochemical properties, with an initial discharge capacity of 162.1 mAh•g−1 and 155.8 mAh•g−1 at current density of 0.1 C and 1C, respectively. The capacity retention reaches 99.4% after 100 cycles at 1C.
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Authors: Rui Li, Xiu Hua Chen, Wen Hui Ma, Jie Xing, Jian Jun Yang, Jie Yu
Abstract: Perovskite-structure La0.7Sr0.3Cr0.5Mn0.5O3-δanode powder was prepared by glycine nitrate process. The result of characterization indicated that the pore morphology and mechanical property of anode support pellets using starch as pore-forming agent are superior to that of using activated carbon. The maximum value of porosity and specific surface area are 40%, 1.256m2/mg at 10MPa, respectively. The conductive mechanism is small-polaron conductive mechanism at low temperature, but it is metalloid conductive mechanism at high temperature.
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