材料期刊网

Beneficiation Study on a Nigerian Baryte Ore for Industrial Use

V. O.Nwoko and O. O. Onyemaobi (Dept. of Materials and Metallurgical Engineering , Federal University of Technology , Owerri , Nigeria)

材料科学技术（英文）

Beneficiation study on samples of baryte ore from Azare in the Plateau State of Nigeria was carried out using chemical analysis, atomic absorption spectrophotometric analysis, jigging and magnetic separation. Results show that Azare baryte can profitably be concentrated for use in oil drilling and other industrial purposes. Barium sulphate content in the head ore analyzed, is 98%. Comparison between jigging and magnetic separation shows that jigging produces a more satisfactory result.

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Effect of the impurity Li(x)Ni(1-x)O on the electrochemical properties of 5 V cathode material LiNi(0.5)Mn(1.5)O(4)

Journal of Alloys and Compounds

The formation of impurity Li(x)Ni(1-x)O when synthesizing spinel LiNi(0.5)Mn(1.5)O(4) using solid state reaction method, and its influence on the electrochemical properties of product LiNi(0.5)Mn(1.5)O(4) were studied. The secondary phase LixNi(1-x)O emerges at high temperature due to oxygen deficiency for LiNi(0.5)Mn(1.5)O(4) and partial reduction of Mn(4+) to Mn(3+) in LiNi(0.5)Mn(1.5)O(4). Annealing process can diminish oxygen deficiency and inhibit impurity Li(x)Ni(1-x)O. The impurity reduces the specific capacity of product, but it does not have obvious negative effect on cycle performance of product. The capacity of LiNi(0.5)Mn(1.5)O(4) that contains Li(x)Ni(1-x)O can deliver about 120 mAhg(-1). (C) 2011 Elsevier B.V. All rights reserved.

关键词: Lithium ion batteries;LiNi(0.5)Mn(1.5)O(4);Impurity Li(x)Ni(1-x)O;Electrochemical properties;lithium batteries;rate capability;spinel;performance

Preparation and properties of machinable Si(2)N(2)O/BN composites

International Journal of Applied Ceramic Technology

Si(2)N(2)O/BN composites were successfully fabricated. With increasing BN content, the elastic modulus and hardness almost linearly decrease while the flexural strength does not exhibit a dramatic degradation. This is attributed to the fact that the homogeneously dispersed nanosized BN particles inhibit the grain growth of Si(2)N(2)O. The critical thermal-shock resistance temperature of the Si(2)N(2)O/30 vol% BN composite is enhanced by 400 degrees C than monolithic Si(2)N(2)O. The introduction of BN significantly improves the dielectric properties and machinability. The Si(2)N(2)O/BN composites show a combination of high strength, low dielectric constant, good thermal shock resistance, and machinability, indicating that they are promising structural/functional materials.

关键词: thermal-shock behavior;nitride/boron nitride nanocomposites;silicon;oxynitride ceramics;mechanical-properties;high-strength;microstructure;toughness;carbide;alumina;system

Service Performance of Engineering Materials

Andrej Atrens

材料科学技术（英文）

Corrosion research by Atrens and co-workers has made significant contributions to the understanding of the service performance of engineering materials. This includes: (1) elucidated corrosion mechanisms of Mg alloys, stainless steels and Cu alloys, (2) developed an improved understanding of passivity in stainless steels and binary alloys such as Fe-Cr, Ni-Cr, Co-Cr, Fe-Ti, and Fe-Si, (3) developed an improved understanding of the melt spinning of Cu alloys, and (4) elucidated mechanisms of environment assisted fracture (EAF) of steels and Zr alloys. This paper summarises contributions in the following: (1) intergranular stress corrosion cracking of pipeline steels, (2) atmospheric corrosion and patination of Cu, (3) corrosion of Mg alloys, and (4) transgranular stress corrosion cracking of rock bolts.

关键词: Stress corrosion cracking , null , null

Phase relations in the ZnO-V(2)O(5)-K(2)O system

Chinese Physics B

The subsolidus phase relations of a ZnO-V(2)O(5)-K(2)O system are investigated by X-ray powder diffraction. There is 1 ternary compound, 11 binary compounds and 14 three-phase regions in this system. The phase diagrams of V(2)O(5)-K(2)O with the K(2)O content ranging from 0 to 71 mol% and pseudo-binary system of ZnO-K(2)ZnV(2)O(7) are also studied by X-ray powder diffraction and differential thermal analysis methods.

关键词: ZnO-V(2)O(5)-K(2)O system;ZnO-K(2)ZnV(2)O(7) system;V(2)O(5)-K(2)O;system;X-ray diffraction;crystal-structure;magnetic-properties;v2o5-zno system;potassium;trivanadates;diffraction;refinement;diagram;oxides;znv2o6

Synthesis of CoFe(2)O(4) nanoparticles with tunable magnetism by the modified hydrothermal method

Journal of Nanoparticle Research

Cobalt ferrite (CoFe(2)O(4)) nanoparticles were synthesized by using the hydrothermal route with the addition of trisodium citrate dihydrate (Na(3)CA center dot 2H(2)O). The formation of CoFe(2)O(4) nanoparticles with size ranging from 13 to 19 nm was confirmed by X-ray diffraction, energy dispersive X-ray analysis, and Fourier transform infrared spectroscopy; the clear-cut sharp of the nanoparticles was observed by transmission electron microscopy. By these characterization methods, the evolution of lattice constant and morphologies of the nanoparticles with the addition of Na(3)CA center dot 2H(2)O is observed. Furthermore, the magnetic hysteresis loops measured at room temperature indicate that the magnetic properties of the products also show clear relationship with the masses of Na(3)CA center dot 2H(2)O. For example, coercivity and high-field paramagnetic susceptibility increase with the increasing masses of Na(3)CA center dot 2H(2)O, whereas the saturation magnetization and the effective magnetic anisotropy constant have the maximum values as the mass of Na(3)CA center dot 2H(2)O is 1 g. This change of magnetic properties is related with the expanded lattice and the varied size and shape because of the addition of Na(3)CA center dot 2H(2)O.

关键词: Cobalt ferrite;Nanoparticles;Hydrothermal method;Magnetism;nanocomposite;nanocrystals;temperature;particles;size

可充电Zn/V_2O_5固态电池

林枫凉 , 薛立新 , 朱斌 , 王大志 , 俞文海

材料研究学报

<正> 蒙脱石是一种丰富廉价的天然矿物,具有开放的层状结构和良好的离子导电性,已被用于固态电池。本文使用蒙脱石为固体电解质研究了可充电的Zn/V_2O_5固态电池的性能。Zn/V_2O_5固态电池的开路电压随着V_2O_5复合阴极中V_2O_5含量的减少而下降,其变

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ZnCr2O4-V2O5-Li2O-ZnO湿敏材料性能再优化研究

徐天华 , 赵越 , 孙彬 , 付恒磊 , 宋伟

功能材料

为进一步优化ZnCr2O4-V2O5-Li2O-ZnO湿敏材料的性能,对制备工艺做了3点改进:在玻璃相V2O5-Li2O-ZnO中掺加SiO2,将晶相原料进行高温烧结；重新筛选烧结制度；测试了样品感湿特性,取得了预期效果.在分析样品微观结构的基础上,对实验结果作了理论解释.

关键词: 湿敏材料 , 晶相 , 玻璃相 , 感湿特性

V₂O₅薄膜电荷储存特性研究

吴广明 , 吴永刚 , 倪星元 , 周箴 , 张慧琴 , 金哲民 , 吴翔

无机材料学报

本文采用真空蒸发制备了V₂O₅薄膜，用电化学方法从Li离子电解质中向V₂O₅薄膜注入Li离子.研究了V₂O₅薄膜中Li离于储存特性、注入／退出可逆性以及电荷注入对其光学性能的影响．实验结果表明，V₂O₅薄膜具有较好的Li离子储存特性和注入／退出可逆性，Li离子的注入量受到膜中V⁵⁺的含量以及锂离子可占据的总位置数限制，而且离子注入后V₂O₅薄膜的光学性能变化较小．

关键词: 薄膜 , null , null , null

Effects of Al2O3-Particulate-Contained Composite Filler Materials on the Shear Strength of Alumina Joints

Jianguo YANG , Hongyuan FANG , Xin WAN

材料科学技术（英文）

Al2O3/Al3O3 joints were brazed with a new kind of filler materials, which were formed by adding Al2O3 particulates into Ag-Cu-Ti active filler metal. The results showed that the material parameters (the Ti content, Al2O3 particulate volume fraction) of the composite filler materials affected the shear strength of brazed joints. When the Ti content was 2 wt pct in the filler metal, the shear strength of brazing joints decreased with the increasing the volume ratio of Al2O3 particulate. When the Ti content was 3 wt pct in the filler metal, the shear strength of joints increased from 93.75 MPa(Al2O3p 0 vol. pct) to 135.32 MPa(Al2O3p 15 vol. pct).

关键词: Composite filler material , null , null , null