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microstructure characteristics of illite from Chuanlinggou Formation of Changcheng System in Jixian County, Tianjin City

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Science China Earth Sciences 2007年第10期50卷 1452-1458页

作者： CHEN Tao1,2 & WANG HeJing2? 1 Institute of Gemology, China University of Geosciences, Wuhan 430074, China 2 School of Earth and Space Sciences, Peking University, Beijing 100871, China Institute of Gemology China University of Geosciences Wuhan China School of Earth and Space Sciences Peking University Beijing China

The microstructure charateristics of illite from the Chuanlinggou Formation of Changcheng System (Chch) in Jixian County, Tianjin City has been studied by means of high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), X-ray energy dispersive spectrum (EDS) and X-ray powder diffraction (XRD). The Kuebler index of ''illite crystallinity'' is 0.505° Δ2θ, which indicates that the host rock is in a middle diagenetic stage. The chemical analyses of EDS for illite studied indicate a heavily absent in interlayer cation and an average chemical formula of K_(0.57)(AI_(1.80)Mg_(0.42)(Fe^(2+))_(0.12))_(∑=2.34)(Si_(2.92)Al_(1.80))_(∑=4)O_(10)(OH)_2. It is found, from one-dimensional lattice images, that the layers of illite not only stack in a flat way but also in a curving way. A ''matting fabric'' illite structure results from stacking faults. Combined with SAED analysis the illite studied can be affirmed as 1M illite. The two-dimensional lattice images are obtained from [100] and [110] incidences, whose lattice images have the same d-values but different intersecting angles. The two-dimensional lattice image with [100] incidence is orthogonal to each other, whilst that with [110] incidence is oblique. This paper provides some important structure information of authigenic clay minerals for the well-known mesoproterozoic section of Jixian County.

关键词： Jixian illite, microstructure, high-resolution transmission electron microscopy (HRTEM), one-dimensional lattice images, two-dimensional lattice images

Preliminary study on enamel microstructure of Yuanmou Miocene hominoids of China

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Science China Earth Sciences 2003年第11期46卷 1142-1150页

作者：赵凌霞郑良高峰姜础 Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing 100044 China Institute of Archaeology of Yunnan Province Kunming 650118 China Yuanmou Man Museum Yuanmou 651300 China

Preliminary study on enamel microstructure of 5 lower permanent incisors of Late Mio-cene Yuanmou hominoids was conducted using a scanning electron microscope (SEM). The enamel incremental markings, as well as perikymata spacing and its periodicity were observed and counted. Using the perikymata number and periodicity, the crown formation times of the incisors are estimated. The transverse and longitudinal microstructures of the enamel prisms are also ob-served. Comparison of the dental development and enamel microstructure features of Yuanmou hominoids with those of Lufeng hominoids shows that there are similarities and also some differ-ences between them. The relationship between Yuanmou hominoids and early hominids is dis-cussed.

关键词： early hominid origin, Yuanmou hominoid, enamel microstructure, dental development.

Synthesis and microstructure analysis of morph- genetic materials

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Science China(Technological Sciences) 2004年第4期47卷 470-478页

作者： ZHANG Di SUN Binghe FAN Tongxiang State Key Laboratory of Metal Matrix Composites Shanghai Jiaotong University Shanghai 200030 China State Key Laboratory of Metal Matrix Composites Shanghai Jiaotong University Shanghai 200030 China State Key Laboratory of Metal Matrix Composites Shanghai Jiaotong University Shanghai 200030 China

Based on the unique character of the natural materials, three types of wood were selected as bio-template. Through infiltrating with various organic or inorganic impregnants, followed by sintering at high temperature, morph-genetic SiC/C, TiC/C ceramics were produced. Observing the microstructure under the SEM and the TEM, the morph-genetic ceramics were shown to retain the intrinsic porous structure of the original wood template, and the resultant was distributed mainly on the surface layer of the cellular wall. The synthesis process had little effect on the hierarchical structure with a wide range from nanometer to micron.

关键词： natural materials, morph-genetic materials, microstructure, pore-size distribution.

microstructure of a-SiO_x:H

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Science China Mathematics 2002年第10期45卷 1320-1328页

作者：王永谦程文超陈长勇陈维德廖显伯李国华张世斌孔光临刁宏伟徐艳月 State Laboratory for Surface Physics Institute of Semiconductors & Center for Condensed Matter Physics Chinese Academy of Sciences Beijing China State Laboratory of Superlattices and microstructures Institute of Semiconductors Chinese Academy of Sciences Beijing China

A set of a-SiOx:H (0.52 microstructure and local bonding configurations of the fil... 详细信息

A set of a-SiOx:H (0.52 microstructure and local bonding configurations of the films are investigated in detail using micro-Raman scattering, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). It is found that the films are structural inhomogeneous, with five phases of Si, Si2O:H, SiO:H, Si2O3:H and SiO2 that coexist. The phase of Si is composed of nonhydrogenated amorphous silicon (a-Si) clusters that are spatially isolated. The average size of the clusters decreases with the increasing oxygen concentration x in the films. The results indicate that the structure of the present films can be described by a multi-shell model, which suggests that a-Si cluster is surrounded in turn by the subshells of Si2O:H, SiO:H, Si2O3:H, and SiO2.

关键词： a-SiOx: H, microstructure, bonding configuration.

Thermal Stress Analysis of Welded Joint in 1420 Al-Li Alloy Induced by Thermal Cycling

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Journal of Materials Science & Technology 2003年第Z1期19卷 205-208页

作者： Hongbin GENG Song HE Dezhuang YANG Space Materials and Environment Engineering Lab. Harbin Institute of Technology Harbin 150001 China Space Materials and Environment Engineering Lab. Harbin Institute of Technology Harbin 150001 China Space Materials and Environment Engineering Lab. Harbin Institute of Technology Harbin 150001 China

A model of double grains under plane stress state has been established. According to the double grain model, thermal stress induced by thermal cycling in welding fusion zone is numerically simulated by finite element method, and the microstructures before and after thermal cycling are observed. The effect of thermal stress on weld microstructure is discussed. Experimental and analysis results show that the difference between the coefficients of thermal expansion and elastic modulus for grains along different crystal directio n can produce alternate thermal misfit stress and strain near boundaries under thermal cycling. At the temperature of upper and lower limit, thermal stress nearby grain boundary reaches maxima. Thermal stress induced changes in microstructure, which expressed by the sending dislocations from boundaries to matrix, piling up against the boundaries and the increasing of dislocation density.

关键词： Thermal cycling, Al-Li alloy, Weld, microstructure, Finite element method

Effect of Filler Composition on the Brazing of Alumina to Copper Using Ultrasonic Wave

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Journal of Materials Science & Technology 2003年第Z1期19卷 176-178页

作者： Khalid M. HAFEZ Masaaki NAKA Joining & Welding Research Institute Osaka University Ibaraki Osaka 567-0047 Japan Joining & Welding Research Institute Osaka University Ibaraki Osaka 567-0047 Japan

An ultrasonic wave was applied during brazing of alumina to Cu. First alumina was metallized by applying ultrasonicwave in braze bath. Then the metallized alumina was brazed with Cu using the same filler alloy. The filler used wereZn-Al alloys and Zn-Sn Alloys. The weight percent of Al in filler was ranging between 0, 5%, 10%, *** weight percent of tin in filler was ranging between 0, 30%, 60% and 91%, respectively. The joining mechanismwas investigated by measuring the joining strength, hardness and analyzing the microstructure at interface of thejoint. The shear strength and microstructure of the joint strongly depend on the filler composition. The effect ofultrasound was derived primarily from acoustic cavitations, impact and friction of the filler against alumina *** improved the wetting between alumina and the filler, and reflected to improve the joint strength. Anotherultrasonic advantage as to reduce of the joining temperature, that reduced the thermal stress in the braze joint.

关键词： Alumina, Copper, Ultrasonic waves, Fracture stress, microstructure, Brazing

Generalized Mathematical Model for Hot Rolling Process of Plate

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Journal of Materials Science & Technology 2003年第Z1期19卷 53-55页

作者： Zhenshan CUI Bingye XU Department of Plasticity Engineering Shanghai Jiaotong University Shanghai 200030 China Department of Engineering Mechanics Tsinghua University Beijing 100084 China

A generalized mathematical model is developed to predict the changes of temperature, rolling pressure, strain,strain rate, and austenite grain size for plate hot rolling and cooling processes. The model is established mainly by incorporating analytical and numerical method for differential equations under complicated boundary conditions. An industrial rolling and cooling process of plate is simulated by the model, in which the thickness of steel Q235B plate is rolled from initial 200 mm to final 12 mm by 13-passes in a two-high mill. The calculated results are in good agreement with measured data. Different from FEM simulation, the model takes very short time in calculation and makes the influence of rolling passes on precision to be very slight.

关键词： Hot rolling, microstructure, Thermomechanical coupling, Simulation

Comparative studies on the structure and adhesion of setae in G. gecko and G. swinhonis

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Science China(Life Sciences) 2007年第6期50卷 831-838页

作者： GUO Ce1, WANG WenBo1, YU Min1, DAI ZhenDong1 & SUN JiuRong2 1 Institute of Bio-inspired Structure and Surface Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China 2 College of Life Science, Peking University, Beijing 100871, China Institute of Bio-inspired Structure and Surface Engineering Nanjing University of Aeronautics and Astronautics Nanjing China College of Life Science Peking University Beijing China

Scanning electron microscopy (SEM) and histological techniques were used to observe and study the setae structures of two gecko species (G. gecko and G. swinhonis) and the relationships between these structures and the adhesive forces. The SEM results showed that the setae of these two species were densely distributed in an orderly fashion, and branched with curved tips. The setae of G. gecko had cluster structures, each cluster containing 4-6 setae whose terminal branches curved towards the center of the toes at ~ 10o, the tips of the branches like spatulae and densely arrayed at an interval of less than 0.2―0.3 μm. On the contrary, the branch tips in the setae of G. swinhonis were curled, and the terminal parts of setae curved towards the center of the toes at various angles. Usually the setae of these gecko species branch twice at the top at intervals greater than that of G. gecko. The histological observation found that inside the setae of these two species there were plenty of unevenly distributed contents, such as epithelia, fat cells, pigmental cells and muscle tissue, but no gland cells existed. The results of functional experiments suggested that modifying the structure of gecko’s setae could reduce its adhesive ability dramatically, demonstrating the positive correlation between the structure of the gecko’s setae and its adhesive ability. The above results provide important information in designing bio-mimic setae and bio-gecko robots.

关键词： G. gecko, G. swinhonis, setae, microstructure, adhesion, bionics

Exploring micropolar effects in thin film lubrication

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Science China(Physics,Mechanics & Astronomy) 2004年第Z1期47卷 65-71页

作者： ZHANG Chaohui LUO Jianbin WEN Shizhu State Key Laboratory of Tribology Tsinghua University Beijing 100084 China State Key Laboratory of Tribology Tsinghua University Beijing 100084 China State Key Laboratory of Tribology Tsinghua University Beijing 100084 China

The micropolar theory for fluids is adopted to probe the effect of the microstructure and microrotation on lubrication features in thin film lubrication. Micropolarity will give rise to an increase in the equivalent viscosity that subsequently leads to a better lubrication. The effective viscosity grown with micro polarity is very close to that of experiment in a preceding work.

关键词： thin film lubrication, microstructure, lubrication features, micropolar, effective viscosity.