材料期刊网

Effects of Sintering on the Microstructure and Critical Current Density of Ag-sheathed BiPbSrCaCuO Superconducting Tapes

Junhua LIU+ , Dept. of Manufacturing Engineering , Beijing University of Aeronautics and Astronautics , Beijing 100083 , ChinaZutang WANG , Dept. of Mechanical Engineering , Tsinghua University , Beijing , 100084 , China

材料科学技术（英文）

The effects of sintering on the microstructure and the critical current density of Ag-sheathed BiPbSrCaCuO (2223) superconducting tapes prepared by the powder-in-tube technique were in- vestigated. The microstructure of oxide layer and the J_C at 77 K were strongly dependent on the sintering condition. The optimum sintering temperature, time and cooling rate to maximize J_C values were in the range about 840-850℃, 100-200 h and 50-100℃/h, respectively.

关键词: BiPbSrCaCuO , null , null , null

用DEPT135测定Resol的组成及微细结构参数

杨金瑞 , 余尚先 , 顾江楠

高分子材料科学与工程

通过对resol(羟甲基酚化合物和低分子量羟甲基酚树脂)DEPT135图谱的分析讨论,得到一系列计算resol微细结构参数的经验公式.根据DEPT135图谱可判断是否发生缩聚反应,根据经验公式可计算酚单体各个活性点参与反应百分率或酚羟基导入率、不同类型缩聚所占百分率及低分子量羟甲基酚树脂的平均核体数.

关键词: 羟甲基酚化合物 , 羟甲基酚树脂 , DEPT135 , 结构参数

Metal Fabrication by Additive Manufacturing Using Laser and Electron Beam Melting Technologies

Lawrence E. Murr

材料科学技术（英文）

Selective laser melting (SLM) and electron beam melting (EBM) are relatively new rapid, additive manufacturing technologies which can allow for the fabrication of complex, multi-functional metal or alloy monoliths by CAD-directed, selective melting of precursor powder beds. By altering the beam parameters and scan strategies, new and unusual, even non-equilibrium microstructures can be produced; including controlled microstructural architectures which ideally extend the contemporary materials science and engineering paradigm relating structure-properties-processing-performance. In this study, comparative examples for SLM and EBM fabricated components from pre-alloyed, atomized precursor powders are presented. These include Cu, Ti-6Al-4V, alloy 625 (a Ni-base superalloy), a Co-base superalloy, and 17-4 PH stainless steel. These systems are characterized by optical metallography, scanning and transmission electron microscopy, and X-ray diffraction.

关键词: Selective laser melting

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

Modeling and control of welding flexible manufacturing cell using petri net

Tao QIU , Shanben CHEN , Yuntao WANG , Lin WU

材料科学技术（英文）

A new welding flexible manufacturing cell (WFMC) with intelligent welding sensors was investigated. Based on the analysis of information flow in WFMC, automation Petri net control model has been studied, which can be extended to complex welding flexible manufacturing system in the future.

关键词:

Calculating Method for Influence of Material Flow on Energy Consumption in Steel Manufacturing Process

YU Qingbo , LU Zhongwu , CAI Jiuju

钢铁研究学报(英文版)

From the viewpoint of systems energy conservation, the influences of material flow on its energy consumption in a steel manufacturing process is an important subject. The quantitative analysis of the relationship between material flow and the energy intensity is useful to save energy in steel industry. Based on the concept of standard material flow diagram, all possible situations of ferric material flow in steel manufacturing process are analyzed. The expressions of the influence of material flow deviated from standard material flow diagram on energy consumption are put forward.

关键词: steel manufacturing process;material flow;energy consumption;calculating method

Biomimicry of bamboo bast fiber with engineering composite materials

Materials Science & Engineering C-Biomimetic Materials Sensors and Systems

Bamboo, one of the strongest natural structural composite materials, has many distinguishing features. It has been found that its reinforcement unit, hollow, multilayered and spirally-wound bast fiber, plays an extremely important role in its mechanical behavior. In the present work, on the basis of the study on bamboo bast fiber and wood tracheid, a biomimetic model of the reinforcing element, composed of two layers of helically wound fiber, was suggested. To detect the structural characteristics of such a microstructure, four types of macro fiber specimens made of engineering composites were employed: axially aligned solid and hollow cylinders, and single- and double-helical hollow cylinders. These specimens were subjected to several possible loadings, and the experimental results reveal that only the double-helical structural unit possesses the optimum comprehensive mechanical properties. An interlaminar transition zone model imitating bamboo bast fiber was proposed and was verified by engineering composite materials. In our work, the transition zone can increase the interlaminar shear strength of the composite materials by about 15%. These biomimetic structural models can be applied in the design and manufacture of engineering composite materials.

关键词: bamboo;bast fiber;biomimetics;engineering composites

Sulfur Flow Analysis for New Generation Steel Manufacturing Process

HU Changqing , ZHANG Chunxia , HAN Xiaowei , YIN Ruiyu

钢铁研究学报(英文版)

Sulfur flow for new generation steel manufacturing process is analyzed by the method of material flow analysis, and measures for SO2 emission reduction are put forward as assessment and target intervention of the results. The results of sulfur flow analysis indicate that 90% of sulfur comes from fuels. Sulfur finally discharges from the steel manufacturing route in various steps, and the main point is BF and BOF slag desulfurization. In sintering process, the sulfur is removed by gasification, and sintering process is the main source of SO2 emission. The sulfur content of coke oven gas (COG) is an important factor affecting SO2 emission. Therefore, SO2 emission reduction should be started from the optimization and integration of steel manufacturing route, sulfur burden should be reduced through energy saving and consumption reduction, and the sulfur content of fuel should be controlled. At the same time, BF and BOF slag desulfurization should be optimized further and coke oven gas and sintering exhausted gas desulfurization should be adopted for SO2 emission reduction and reuse of resource, to achieve harmonic coordination of economic, social, and environmental effects for sustainable development.

关键词: material flow analysis;sulfur flow analysis;steel industry;sustainable development;SO2 emission

Strengthening Materials by Engineering Coherent Internal Boundaries at the Nanoscale

Science

Strengthening materials traditionally involves the controlled creation of internal defects and boundaries so as to obstruct dislocation motion. Such strategies invariably compromise ductility, the ability of the material to deform, stretch, or change shape permanently without breaking. Here, we outline an approach to optimize strength and ductility by identifying three essential structural characteristics for boundaries: coherency with surrounding matrix, thermal and mechanical stability, and smallest feature size finer than 100 nanometers. We assess current understanding of strengthening and propose a methodology for engineering coherent, nanoscale internal boundaries, specifically those involving nanoscale twin boundaries. Additionally, we discuss perspectives on strengthening and preserving ductility, along with potential applications for improving failure tolerance, electrical conductivity, and resistance to electromigration.

关键词: strain-rate sensitivity;stacking-fault energy;nano-scale twins;cu-al;alloys;nanocrystalline metals;mechanical-properties;activation;volume;copper;deformation;behavior

Crystal facet engineering of semiconductor photocatalysts: motivations, advances and unique properties

Chemical Communications

Crystal facet engineering of semiconductors has become an important strategy for fine-tuning the physicochemical properties and thus optimizing the reactivity and selectivity of photocatalysts. In this review, we present the basic strategies for crystal facet engineering of photocatalysts and describe the recent advances in synthesizing faceted photocatalysts, in particular TiO(2) crystals. The unique properties of faceted photocatalysts are discussed in relation to anisotropic corrosion, interaction dependence of adsorbates, photocatalytic selectivity, photo-reduction and oxidation sites, and photocatalytic reaction order. Ideas for future research on crystal facet engineering for improving the performance of photocatalysts are also proposed.

关键词: shape-controlled synthesis;exposed 001 facets;rutile tio2 nanorods;visible-light photocatalysis;solvent-solute interactions;anatase;titanium(iv) oxide;low-temperature synthesis;ordered solid-phases;platinum nanocrystals;hydrogen-production