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Preparation and particle size characterization of Cu nanoparticles prepared by anodic arc plasma

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Rare metals 2006年第2期25卷 172-176页

作者： WEI Zhiqiang XIA Tiandong FENG Wangjun DAI Jianfeng WANG Qing LI Weixue YAN Pengxun School of Sciences Lanzhou University of Technology Lanzhou 730050 China College of materials Science and Engineering Lanzhou University of Technology Lanzhou 730050 China Institute of Plasma and metal materials Lanzhou University Lanzhou 730000 China

Copper nanoparticles were successfully prepared in large scale by means of anodic arc discharging plasma method in inert atmosphere. The particle size, specific surface area, crystal structure, and morphology of the samples were characterized by X-ray diffraction （XRD）, BET equation, transmission electron microscopy （TEM）, and the corresponding selected area electron diffraction （SAED）. The experimental results indicate that the crystal structure of the samples is fcc structure the same as that of the bulk materials. The specific surface area is 11 m^2/g, the particle size distribution is 30 to 90 nm, and the average particle size is about 67 nm obtained from TEM and confirmed from XRD and BET results. The nanoparticles with uniform size, high purity, narrow size distribution and spherical shape can be prepared by this convenient and effective method.

关键词： metal materials Cu nanoparticles anodic arc plasma particle size structure

Comprehensive utilization of metal materials for steelmaking at Baosteel

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Baosteel Technical Research 2013年第4期7卷 33-37页

作者： MA Zhigang DI Yongzhong WU Weimin HU Hantao Steelmaking Plant Baoshan Iron & Steel Co.Ltd. Steelmaking Technonlogy Department Research InstituteBaoshan Iron & Steel Co.Ltd.

Optimization of scrap utilization, through maintaining a reasonable heavy scrap ratio, determination of scrap yield, development of substitutes for scrap, recycling of high-alloy scrap and optimization of scrap utilization technology, was investigated in this paper, in terms of the supply of metal materials, production cost, production quality and environment protection. Then, recycling of solid waste resources was discussed, and the utilization conditions and methods of slag-steel, slag-iron, steel-slag, etc. were determined. Finally, the management system for comprehensive resource utilization was introduced.

关键词： metal materials scrap comprehensive utilization

Enhancement of the orientation and adhesion of Al films on LiNbO_3 with Ni underlayer

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Rare metals 2005年第4期24卷 363-369页

作者： LI Dongmei PAN Feng NIU Jiebin LIU Ming Laboratory of Advanced materials Department of Materials Science and Engineering Tsinghua University Beijing 100084 China Institute of Chemistry and Chemical Engineering of Xinjiang University Wulumuqi 830046 China Institute of Microelectronics Chinese Academy of Sciences Beijing 100029 China

Al/Ni films were deposited on 128° Y-X LiNbO3 substrates by e-beam deposition. The influence of Ni underlayer on the microstructure, adhesion and resistivity of the Al/Ni films was investigated. It was found that Al films deposited on Ni underlayer thinner than 5 nm possessed strong texture. The textured Al/Ni films had a superior adhesion. Their resistivity decreased after annealing treatment at 200℃ for 30 min. With the textured Al/Ni films, a 2,30 GHz-range image-impedance connection SAW （Surface Acoustic Wave） filter was successfully fabricated.

关键词： metal materials Al/Ni films electron-beam evaporation microstructure surface acoustic wave

Analysis of Valence Electron Structure of RE in Solid Solution in Medium and Low Carbon Steel

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Journal of Rare Earths 2004年第2期22卷 282-287页

作者：朱莹光刘艳刘志林刘伟东 Department of Material and Chemical Engineering Liaoning Institute of Technology Jinzhou 121001 (China College of Science Northeastern University Shenyang 110006 ChinaDepartment of Material and Chemical Engineering Liaoning Institute of Technology Jinzhou 121001 (China

According to EET theory, the valence electron structures of RE in the solid solution of austenite, pearlite and martensite were calculated. The influence of RE in solid solution on phase transformation of pearlite and recrystallization of martensite was explained by the valence electron structure data of phases. Calculating results indicate that C element is favorite to enhance the number of RE in the solid solution. RE in the solute solution shortens the incubation period of proeutectoid ferrite, increases its quantity and carbon content, decreases the quantity of pearlite and thickness of its lamellas and lamellar spacing, then the strength and hardness of pearlite are improved and granular pearlite can be obtained. RE dissolved in martensite intensifies martensite, enhances tempering stability of martensite, increases its recrystallization temperature and prolongs the holding time needed during tempering.

关键词： metal materials valence electron structure phase transformation recrystallization rare earths

Preparation and crystalline phase of a TiO_2 porous film by anodic oxidation

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Rare metals 2005年第4期24卷 330-335页

作者： WANG Wei TAO Jie ZHANG Weiwei TAO Haijun WANG Ling College of Material Science and Technology Nanjing University of Aeronautics ＆ Astronautics Nanjing 210016 China

Anatase titanium dioxide is an active photocatalyst, but it is difficult to immobilize on the substrate. A crystalline TiO2 porous film was prepared directly on the surface of pure titanium by anodic oxidation in this work. Constant voltage and constant current anodic oxidation were adopted with sulphuric acid used as the electrolyte, pure titanium as the anode and copper as the cathode. The morphology and structure of the porous film on the substrate were analyzed with the aid of Field Emission Scanning Electron Microscopy （FESEM） and X-ray Diffraction （XRD）. The effects of the parameters of anodic oxidation （such as voltage, the concentration of sulphuric acid, anodization time and current density） on the aperture and the crystalline phase of the TiO2 porous film were systematically investigated. The results indicate that the increase of current density facilitates the augment of the aperture and the generation of anatase and mille. In addition, the forming mechanism of anatase and mille TiO2 porous films was discussed.

关键词： metal materials titanium oxide porous film anodic oxidation anatase rutile

Friction and Wear Characteristics of Mg-Al Alloy Containing Rare Earths

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Journal of Rare Earths 2003年第2期21卷 157-162页

作者：祁庆琚刘勇兵杨晓红 College of materials Science and Engineering Jilin University

The influence of rare earth on the friction and wear characteristics of magnesium alloy AZ91 and AM60 were studied. The results show that the wear resistance properties of rare earth magnesium alloys are better than those of matrix alloy under the testing conditions. The anti wear behaviour of AZ91 alloy is much better than that of AM60 alloy. In dry sliding process,magnesium alloys undergo a transition from mild wear to severe wear. The addition of rare earths refine the structure of alloys, improve the comprehensive behaviors of magnesium alloys, increase the stability of oxidation films on worn surfaces, enhance the loading ability of rare earth magnesium alloys, and delay the transition from mild wear to severe wear effectively.

关键词： metal materials magnesium alloy friction and wear rare earths

Effects of RE on Microstructures and Mechanical Properties of Hot-Extruded AZ31 Magnesium Alloy

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Journal of Rare Earths 2004年第4期22卷 527-532页

作者：刘英陈维平张卫文张大童李元元 Key Laboratory for Advanced metallic materials Processing and Forming of Guangdong South China University of Technology Guangzhou 510640 China

Effects of rare earth (RE) additions on microstructure and mechanical properties of the wrought AZ31 magnesium alloy were investigated. The results show that, by adding 0.3%, 0.6% and 1.0% RE elements, the as-cast microstructure can be refined, and the as-cast alloys′ elongation and tensile strength can be improved. After extrusion, the alloy with 0.3% and 0.6% RE additions obtain a finer microstructure and the best mechanical properties, but the alloy with 1.0% RE addition has the coarse Al-RE compound particles in grain boundaries which decreased elongation and tensile properties. Usually, Rare earth (RE) elements were used to improve the creep properties of aluminium-containing magnesium pressure die cast alloys at elevated temperatures. In this paper, it is also found that the high temperature strength of extruded materials can be increased by RE elements additions.

关键词： metal materials AZ31 magnesium alloy rare earth element microstructure mechanical properties

Solidification Behavior of Laser Melting Layer of Nd_(15)Fe_(77)B_8 Sintered Magnets and Its Microstructures Evolution

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Journal of Rare Earths 2005年第2期23卷 208-215页

作者：潘晶刘新才 Department of Physics Faculty of Sciences Ningbo University Ningbo 315211 China

To research the solidification behavior and microstructures of a laser remelting/solidification layer on anisotropic Nd_(15)Fe_(77)B_(8 )sintered magnets with their magnetization direction parallel to X, Y, Z-axis respectively, their surfaces (parallel to XOY plane) were scanned by 5 kW Roffin-Sinar 850 type of CO_(2) laser along Y axis. The rapid solidification of the molten alloy in the layer results in three distinct zones. The transition zone close to the unmolten portion of a magnet (substrate), consists of the columnar Nd_(2)Fe_(14)B phase (matrix), the 10.0%~15.1% dendrite primary iron phase dispersing in the matrix, and the Nd-rich phase along Nd_(2)Fe_(14)B grain boundaries. The columnar crystal zone in the middle of the layer consists of the long columnar Nd_(2)Fe_(14)B grains and their grain boundary Nd-rich phase. And the dendrite crystal zone near the free surface of the layer consists of dendrite Nd_(2)Fe_(14)B grains and their grain boundary Nd-rich phase. When the laser scanning velocity is lower, the growing direction of the microstructures in the layer tends to the laser scanning direction step by step. When the velocity is not lower than 25 mm·s^(-1), the laser remelting/solidification layer thins and the columnar crystal zone comprises almost the whole layer. Under this condition, on the substrate with its magnetization direction along X or Y-axis respectively, the columnar Nd_(2)Fe_(14)B grains in the layer grow in the direction of Z-axis (that is their long-axis along Z-axis), their alignment of the easy magnetization axis [001] is parallel to the magnetization direction of the substrate correspondingly; but on the substrate with its magnetization direction along Z-axis, the columnar Nd_(2)Fe_(14)B grains in the transition zone grow at an angle of 30°~50° between Z-axis and their long-axis. And the columnar Nd_(2)Fe_(14)B grains in the columnar crystal zone gradually tend to the Z-axis,and their easy magnetization axis [001] arrange in the range of 0°~360° of the plane perpendicular to their

关键词： metal materials crystal growth microstructures laser rapid solidification magnetic materials neodymium compounds magnetic domains rare earths

Effect of Rare Earth Composite Modification on Microstructure and Properties of a New Cast Hot-Work Die Steel

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Journal of Rare Earths 2003年第3期21卷 368-371页

作者：关庆丰方建儒姜启川王树奇 Department of materials Science and Engineering Jilin University

The effects of RE modification on structure and the properties of a new cast hot work die (CHD) steel were investigated. The grains of the CHD steel are refined by RE modification. With the increase of RE addition, both grain size and inclusion amount are reduced. Appropriate amount of RE results in decrease in inclusion amount and formation of spheroidal inclusions uniformly-distributed in steel, so that the morphology and distribution of inclusions are improved. RE composite modification favors the formation of bainite, austenite and fine lath martensite with dense dislocation. When the residual RE content reaches 0.02%, no obvious changes in strength and hardness are found, while fracture toughness and threshold of fatigue crack growth are increased. The impact toughness, elongation and reduction of cross sectional area are increased by a factor of two, and thermal fatigue resistance is also improved.

关键词： metal materials modification cast hot work die steel thermal fatigue rare earths