检索结果-南通市图书馆

The mathematical model of wetting angle of heterogeneous nucleation

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2004年第4期47卷 391-397页

作者： HUANG Cheng1, SONG Bo1, MAO jinghong2.& ZHAO Pei3.1. School of metallurgical and Ecological engineering, University of {2. and technology beijing, beijing 100083, china 2. School of Material {2., University of {2. and technology beijing, beijing 100083, china 3. Central Iron and Steel Research Institute, beijing 100081, china 1. School of metallurgical and Ecological engineering University of Science and Technology Beijing 100083 Beijing China 2. School of Material science University of Science and Technology Beijing 100083 Beijing China 3. Central Iron and Steel Research Institute 100081 Beijing China

The heterogeneous nucleation has been analyzed in terms of the thermodynamic theory, and the mathematical model of wetting angle of heterogeneous nucleation has been developed based on the dynamic requirements of hetero- and homogeneous nucleation. With the wetting angel model, the wetting angles of different catalysts in liquid iron have been calculated. The result shows that the wetting angle of most catalysts is smaller than 40, and the value of f() is far less than 1. The wetting angles of TiN, TiC and RE2.3.are smaller, while the wetting angle of MnO is bigger among the ordinary nucleation catalysts. The wetting angles calculated by this model are in agreement with the results of other research work.

关键词： heterogeneous nucleation, mathematical model, wetting angle, undercooling.

Application of the annexation principle to the study of thermodynamic properties of ternary metallic melts In-Pb-Ag and In-Bi-Sb

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2002年第2期21卷 142-151页

作者： zhang jianmetallurgical {2. school.University of {3. and technology beijing, beijing 100083, china metallurgical engineering School University of Science and Technology Beijing 北京 100083

Based on the phase diagrams, measured activities an the annexationprinciple, the calculating models of mass action concentrations forin-Pb-Ag and In-Bi-Sb ternary metallic melts have been *** results of calculation both agree with practice, and obey the lawof mass action, showing that the models formulated can reflect thestructural reality of the corresponding melts and the annexationprinciple is applicable to the them.

关键词： activity mass action concnetration th annexation principle In-PB-Ag

Thermodynamic properties and mixing thermodynamic parameters of binary homogeneous metallic melts

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2003年第1期22卷 25-32页

作者： zhang Manmetallurgical {2. School, University of {3. and technology beijing, beijing 100083, china metallurgical engineering School University of Science and Technology Beijing 北京 100083

After the investigation on the thermodynamic properties and mixingthermodynamic parameters of binary homogeneous metallic melts involving compound, peritectic as wellas solid solution, it was found that the equations of mixing free energy DELTA G^m and excess freeenergy DELTA G^(XS) of them can he expressed by the following equations: DELTA G^m = SIGMA x [SIGMAN_i DELTA G_I^(THETA) + RT(SIGMA N_j ln N_j + SIGMA N_i ln N_i )] and DELTA G^(XS) = DELTA G^m -RT(a ln a + b ln b), respectively.

关键词： metallic melt mixing thermodynamic parameter coexistence theory activity mass action concentration

Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2006年第5期49卷 521-536页

作者： CHEN Zhiyong1,2. CAI Hongnian1, zhang Xinming2. WANG Fuchi1 & TAN Chengwen1,3.1. School of Material {3. and {2., beijing Institute of technology, beijing 100081, china 2. School of Material {3. and {2., Central South University, Changsha 410083. china 3. School of Material {3. and {2., beijing University of Aeronautics and Astronautics, beijing 100083, china 1. School of Material science and engineering Beijing Institute of Technology Beijing 100081 China 2. School of Material science and engineering Central South University Changsha 410083 China 3. School of Material science and engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112.and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.

关键词： twinning slip face-centered cubic crystals axisymmetric co-deformation Bishop-Hill maximum work principle yield strength anisotropy

Effects of Na/K ratio on the phase structure and electrical properties of Na_xK_(1-x)NbO_3.lead-free piezoelectric ceramics

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2010年第2期29卷 220-225页

作者： zhang Qian, zhang Boping, Li Haitao, and SHANG Pengpeng School of Materials {2. and {3., University of {2. and technology beijing, beijing 100083, china School of Materials science and engineering University of Science and Technology Beijing

Lead-free piezoelectric NaxK1-xNbO3.x = 0.3.0.8）（NKN） ceramics were fabricated by normal sintering at 1060°C for 2.*** and electrical properties of the ceramics were investigated with a special emphasis on the influence of Na *** grain size of the produced dense ceramic was decreased by increasing Na content.A discontinuous change in the space distance was found at the composition close to Na0.7K0.3.bO3.ceramic, which indicates the presence of a transitional composition between two different orthorhombic phases, which is similar to the behavior of morphotropic phase boundary（MPB） in NaxK1-xNbO3.*** MPB-like behavior contributes to the enhanced piezoelectric coefficient d3. of 12. pC/N, planar-mode electromechanical coupling coefficient kP of 2..6%, and dielectric constant εr of 703. respectively for the Na0.7K0.3.bO3.*** temperature TC and the transitional temperature TO-T from orthorhombic to tetragonal phase are observed at around 42.°C and 2.0°C, respectively.

关键词： lead-free piezoelectric ceramics NKN sintering morphotropic phase boundary(MPB)

SEM in-situ Fatigue Observation on Crack Initiation and Growth from Inclusion in P/M Rene95 Superalloy

在线全文

学校读者我要写书评

暂无评论

journal of University of science and technology {2. 2001年第3期8卷 195-197页

作者： Lina zhang, jianxin Dong, Xishan Xie Material science and {2. School, University of science and technology beijing, beijing 100083, china Univ Sci & Technol beijing Sch Mat Sci & Engn Beijing 100083 Peoples R China

A special designed experiment was conducted for observing crack initiation and growth in P/M Rene95 superalloy under tension-tension loading by self-made SEM in-situ fatigue loading stag. Several alumina inclusion particles exposed at the specimen surface were observed carefully. During fatigue test inclusions led to cracks initiation. The cracks can be formed by two mechanisms. Generally, the cracks nucleated at the interface between inclusion and matrix. Sometimes, cracks were also formed inside the inclusion. As the increase of cycles, some cracks at the interface between inclusion and matrix broadened and propagated along the direction about 45 degrees to the loading axis. On the other hand, the cracks inside the inclusion propagated in the inclusion and towards matrix.

关键词： inclusion P/M superalloy LCF SEM in-situ fatigue

Fabrication of pure copper rods containing continuous columnar crystals by continuous unidirectional solidification technology

在线全文

学校读者我要写书评

暂无评论

journal of University of science and technology {2. 2004年第3期11卷 240-244页

作者： Hong zhang jianxin Xie Zidong Wang Materials science and {2. School, University of science and technology beijing, beijing 100083, china Mat. Sci. and Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

Pure copper rods containing continuous columnar crystals were fabricatedusing the downward CUS (Continuous Unidirectional Solidification) equipment. When the technologicalparameters were set as the ranges of mould temperature 1100-13.0℃, cooling distance (the distancefrom the exit of the cast mould to the start point of cooling) 10-2. mm, casting speed 0.2.2.5 mm/s,cooling water (2.-2.℃) volume 1000-13.0} L/h, and when these parameters matched reasonably, the CUSprocess was performed stably, and pure copper rods containing continuous columnar crystals withbright and smooth surface were produced. The dendritic arm spacing of the crystals in copper rodsdecreased with increasing the casting speed. The results of the texture by X-ray diffractionanalysis showed that the rods has strong fiber texture.

关键词： copper continuous unidirectional solidification mould temperature castingspeed microstructure texture

A COMPUTERIZED SYSTEM ON KINETIC ANALYSIS AND EVALUATION OF GAS/SOLID REACTIONS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2003年第6期16卷 495-506页

作者： j.H. Liu, j. Y. zhang and S.K. WeiSchool of metallurgical and Ecological {2., University of {3. & technology beijing, beijing 100083, china School of metallurgical and Ecological engineering University of Science & Technology Beijing

The present paper presents the structure, features and functions of a computerized system on kinetic analysis and evaluation of gas/solid reactions, KinPreGSR. Kin-PreGSR is a menu driven system, can be operated with MS Windows as workbench in a PC computer. It has been developed using visual C++ with FoxPro hybrid coding technique.KinPreGSR combines the characteristics of gas/solid reactions with the kinetic models as well as mass and heat transfer equations. The database files were established for the apparent activation energies of some reduction and decomposition reactions to allow the prediction of the reaction kinetics to some extents. Outputs can be displayed using graphical or numerical forms. Examples regarding the oxide reduction and carbonate decomposition under isothermal conditions are given to show those functions.

关键词： gas/solid reaction kinetics computer system evaluation anal-ysis

Future Trends of Deep Sea Bed Mining technology

在线全文

学校读者我要写书评

暂无评论

International journal of Minerals,Metallurgy and Materials 1999年第1期13卷 4-7页

作者： Yan Feng Haoran Li Wenming zhang (Resources engineering School, University of {2. and {3. beijing, beijing 100083, china) Resources engineering School University of Science and Technology Beijing Beijing 100083 China

The present status of deep sea bed mining technology for polymetallic nodules has been critically examined in light of its history of development the UNCLoS (the United Nation Convention on the Law of the Sea) regime and the current trends in *** critical technologies have been highlighted and the need for system integration underscored. The deep sea bed environment and the engineering challenge were presented and the necessary features of the deep sea bed mining system for commercial mining was analyzed. The key accomplishments, problems and future bends in research in the development of the mining system are also discussed. Finally, it points out that the technology gaps can be filled by the bine commercial mining is undertaken as a result of market conditions in its favor.

关键词： deep sea bed mining, UNCLoS TIS (Total Integrated System), polymetallic nodules mining system