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Laser Surface Hardening of 9CrSi Steel

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Journal of Materials Science & Technology 2002年第1期18卷 17-20页

作者： Nunghee RYU and Sunggoon KANGDivision of Materials Science and eng.neering, coll.ge of eng.neering, Hanyang University, Korea [ Manuscript received August 7, 2001, in revised form September 20, 2001] Div. of Mat. Sci. and eng. Coll. of Eng. Hanyang Univ. Hanyang South Korea

The effects of laser hardening parameters such as beam power, beam diameter and scanning rate on microstructure and hardness of 9CrSi steel were investigated. The microstructure of the surface layer of 9CrSi steel was changed from pearlite to martensite, retained austenite and carbide by laser hardening. The depth of the hardened layer increased with increasing laser energy density and the surface hardeness increased by 3-5 times as high as the untreated steel. The laser hardened surface had good wear resistance due to martensite and carbide in the surface layer. The wear mode at low speed was abrasive, while the wear mode at high speed was adhesive.

关键词： Laser hardening Martensite Hardeness Phase trasformation

SHORT FATIGUE CRACK PARAMETER BASED ON THE TOTAL CRACK AREA

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Acta Metallurgica Sinica(eng.ish Letters) 2001年第4期14卷 235-240页

作者： Z.X. Wu and X. C. Wu eng.neering coll.ge, Yangzhou University, Yangzhou 225009, China eng. coll. Yangzhou Univ. Yangzhou 225009 China

The progressive fatigue damage of a material is closely related to the whole population of cracks on its surface. In order to understand which parameter is a more useful indicator of fatigue damage, rotatory bending fatigue tests were carried out using smooth specimens of medium-carbon steel. The behavior of short crack propagation during fatigue was examined and a new parameter total crack area was suggested. The aim of this paper is to extend the research on fatigue damage in the already studied steel and to study how these damage parameters are correlated with the process of fatigue damage in order to evaluate the effectiveness of damage detection methods.

关键词： Bending streng.h Crack initiation Crack propagation Fatigue testing Parameter estimation

FLOW FIELD CHARACTERISTICS OF THE SAND FUNNEL AND ITS MECHANICS OF SEDIMENT TRANSPORT

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Journal of Hydrodynamics 2002年第3期14卷 130-134页

作者： Wang, Shun-Jiu Zhou, Zhu Hou, Jie Qiu, Xiu-Yun Ding, Jing Hou, Yu coll. of hydraulic eng. Sichuan Univ. Chengdu 610065 China coll. of Water Conservancy Xinjiang Agric. Univ. Wulumuqi 830052 China coll. of Hydropower eng. Sichuan Univ. Chengdu 610065 China Dept. of Geogr. Zhongshan Univ. Guangzhou 510275 China

The flow in funnel chamber is typical three-dimensional flow. The experimental results of clear water flow field and muddy water flow field show that the flow characteristics in the funnel chamber are favorable to the separation of water and sand. Tangential velocity sustains the vortex streng.h of the funnel chamber, axial velocity is benefit to the sediment sinking, and radial velocity is benefit to sediment moving to desilting hole. So the sand funnel is successful in sediment disposal. The sand funnel projection has also good desilting effectiveness in practice. Its average flushing discharge is 3% of inlet canal discharge, the sand disposal rate is 100% for the sand with grain diameter of more than 0.5 mm, and is more than 90% for the sand with grain diameter of less than 0.5 mm.

关键词： Mechanics Sand Sediments Three dimensional Vortex flow Water

Fluvial Processes in the Meandering Reach of the Lower Wei River During the Course of Degradation

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四川大学学报（工程科学版） 2005年第S1期37卷 46-51页

作者： Xia, Junqiang Wang, Guangqian Wu, Baosheng Dept. of hydraulic eng. Tsinghua Univ. Beijing 100084 China

This paper presents an analysis of the changes of the longitudinal and lateral profiles in the meander- ing reach of the Lower Wei River over the period from October 1973 to October 1976 during the course of *** results indicated that retrogressive erosion and subsequent downstream erosion occurred in the reach due to the lowering in the Tongguan elevation and the inflowing water carrying low sediment con- *** the end of the degradation,the main channel widths of the majority ...

关键词： the Lower Wei River fluvial processes batse level of erosion channel widening channel undercut

Sedimentological and Chemical Processes During Flushing Tests at Iffezheim Barrage(River Rhine)

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四川大学学报（工程科学版） 2005年第S1期37卷 7-15页

作者： Silke WIEPRECHT Inst.of hydraulic eng. Univ.Stuttgart70550 StuttgartGermany

This paper analyzes the situation at the Iffezheim barrage along the fiver *** the start of operation in 1977 several million cubic meters of very fine sediment have been deposited in the ***- cause of stability problems and reduced safety in the event of flooding,an extraction of the material is neces- *** assays showed a high concentration of *** flushing without any additional measures is not *** order to leam more about the morphological and chemical in...

关键词： sedimentation in reservoirs flushing suspended material HCB

MULTI-SCALE NUMERICAL MODEL FOR SIMULATING CONCRETE MATERIAL BASED ON FRACTAL THEORY

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Acta Mechanica Solida Sinica 2013年第4期26卷 344-352页

作者： Qiang Xu Jianyun Chen Jing Li Mingming Wang School of Civil and hydraulic eng. Dalian University of Technology State Key Lab. of Coastal and Ofshore eng. Dalian University of Technology

A new multi-scale numerical model is presented using the fractal theory and adopting FEM to simulate the failure of *** relation between the fractal box dimension in large scale and the damage to concrete in small scale is *** the evolutionary process of elastic modulus and streng.h in small scale is ***,the multi-scale numerical model is proposed to describe the constitutive relation of concrete between small scale and large scale.A two-dimensional static analysis of a concrete block is performed by using this model and the calculation result is *** propagation of cracks of the concrete block is also studied.

关键词： fractal theory concrete material fractal box dimension damage multi-scale constitutive relation

Thermodynamics of Modifying Effect of Rare Earth Oxide on Inclusions in Hardfacing Metal of Medium-High Carbon Steel

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Journal of Rare Earths 2002年第4期20卷 291-294页

作者：赵研辉李艳丽姚枚杨庆祥 coll. of Mat. Sci. and eng. Yanshan Univ. Qinhuangdao 066004 China

The modifying effect of rare earth (RE) oxide on inclusions in hardfacing metals of medium-high carbon steel was investigated by means of thermodynamics. The thermodynamic analysis for inclusion formation shows that RE oxide can be reduced to RE element by carbon, then the RE element can react with oxygen and sulfur to form the RE oxide, RE sulfide and RE oxide-sulfide in hardfacing molten pool. The deoxidization and the desulphurization can be carried out and the liquid metal can be purified. In addition, RE oxide can also react with sulfur to form RE oxide-sulfide directly. Therefore, the harmful effect of sulfur can be decreased.

关键词： rare earths oxide inclusion hardfacing metal thermodynamics

Characterization of ZnO Based Varistor Derived from Nano ZnO Powders and Ultrafine Dopants

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Journal of Materials Science & Technology 2005年第2期21卷 183-186页

作者： Weizhong YANG, Dali ZHOU, Guangfu YIN, Runsheng.WANG and Yun ZHANG coll.ge of Material Science and eng.neering, Sichuan University, Cheng.u 610064, China coll. of Mat. Sci. and eng. Sichuan Univ. Chengdu 610064 China

Nanosized ZnO powders were prepared with a two-step precipitation method. The average size of ZnO particles was about 80 nm and their size distribution was narrow. Combining with ultrafine additive powders, ZnO base varistor was produced via an oxide mixing route. ZnO varistor derived from normal reagent grade starting materials was investigated for comparison purpose. Outstanding microstructure of the ZnO varistor derived from nanosize ZnO powders and ultrafine dopants was obtained: uniform distribution of fine ZnO grains (less than 3 microns), grain boundary and the dopant position. Higher varistor voltage (U=492 V/mm) and nonlinear coefficient (α=56.2) as well as lower leakage current (TL=1.5 μuA) were achieved. The better electrical properties were attributed to the uniform microstructure, which in turn led to stable and uniform potential barriers. Also this improved technique is more feasible for producing ZnO nanopowders and resulting varistor in large scales.

关键词： Zinc oxide (ZnO) Varistor Nanopowders Ultrafine dopants Two-step precipitation

Synthesis and Crystal Structure of 4,6Di-tert-butyl-2-hydroxy-3-(N-1-phenylethyliminomethyl) phenyl bis(triphenylphosphine)palladium bromide

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Chinese Journal of Structural Chemistry 1999年第4期18卷 54-59页

作者： XU JiaXi\ ZHANG ZeYing\= (coll.ge of Chemistry and Molecular eng.neering, Peking University, Beijing 100871, China) coll. of Chem. and Molec. eng. Peking University Beijing 100871 China

１ＩＮＴＲＯＤＵＣＴＩＯＮＰａｌａｄｉｕｍｃｏｍｐｌｅｘｅｓｓｕｃｈａｓｔｅｔｒａｋｉｓ（ｔｒｉｐｈｅｎｙｌｐｈｏｓｐｈｉｎｅ）ｐａｌａｄｉｕｍａｒｅａｋｉｎｄｏｆｉｍｐｏｒｔａｎｔｃａｔａｌｙｓｔｓｉｎｔｈｅｒｅａ... 详细信息

１ＩＮＴＲＯＤＵＣＴＩＯＮＰａｌａｄｉｕｍｃｏｍｐｌｅｘｅｓｓｕｃｈａｓｔｅｔｒａｋｉｓ（ｔｒｉｐｈｅｎｙｌｐｈｏｓｐｈｉｎｅ）ｐａｌａｄｉｕｍａｒｅａｋｉｎｄｏｆｉｍｐｏｒｔａｎｔｃａｔａｌｙｓｔｓｉｎｔｈｅｒｅａｃｔｉｏｎｏｆｃａｒｂｏｎｃａｒ...

关键词： palladium complex synthesis molecular structure crystal structure