检索结果-南通市图书馆

Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 362-370页

作者： A.L. Wang h.b. yin M. Ren X.N. Cheng Q.F. Zhou X.F. Zhang Faculty of Chemistry and Chemical Engineering Jiangsu University Zhenjiang 212013 China Department of Chemical Engineering Jiangsu Teachers University of Technology Changzhou 213001China

Silver nanoparticles with average particles sizes ranging from 2 to 131nm were manipulatively synthesized starting from silver nitrate using different functional group-containing organic modifiers at room temperature. The effects of the organic modifiers on the morphology of the resulting silver nanoparticles were strongly dependent on the intrinsic properties of the functional groups and the reducibility of the reductant. Numerous ether bonds （-0-）present in polyethylene glycol and Tween-80 were beneficial to the formation of silver nanoparticles with particle sizes of several nanometers in a narrow size distribution in both weak and strong reducing environments. Cetyltrimethylammonium bromide induced the formation of nanosized silver triangle plates in a weak reducing environment. The crystal growth of the silver nanoparticles with particle sizes of more than lOnm was postulated through an adhesion process of small-sized particles followed by a subsequent coalescence process under the present reaction conditions.

关键词： silver nanoparticle nanostructure crystal growth TEM (transmissionelectron microscopy)

Assessment of deterioration in RhA-concrete due to magnesium sulphate attack

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2010年第6期17卷 691-696页

作者： G.A. h.b.eb h.b. Mahmud N.b.A.A. hamid Department of Civil Engineering Faculty of Engineering University of Malaya

The assessment of magnesium sulphate attack on concretes containing rice husk ash （RhA, 20wt% of the cementitious materials） with various average particle sizes was investigated. The total cementitious materials were 390 kg and the water-to-binder ratio （W/b） was 0.53 for all mixtures. Specimens were initially cured in water for 7 d and then immersed in the 3wt% magnesium sulphate solution for up to 111 d of exposure. The specimens were subjected to drying-wetting cycles to accelerate sulphate attack. In addition to the visual monitoring of the specimens, the concrete specimens were subsequently tested for compressive strength, dynamic modulus of elasticity, and length and mass changes. The results show that the specimens exposed to sulphate attack exh.b.t higher strength and dynamic modulus than those kept in water. The length change is negligible and can be attributed to the normal swelling of concrete. On the other hand, concretes suffers mass loss and surface spalling and softening; the fine RhA-concrete results in a better resistance. For the accelerated sulphate attack method used in this study, mass change and visual monitoring are recommended for assessing the deterioration degree and the effectiveness of supplementary cementitious materials to resist sulphate attack.

关键词： concretes pozzolan ettringite rice husk ash (RhA) magnesium sulphate

EXPERIMENTAL AND ThEORETICAL INVESTIGATION OF PSEUDOELASTIC hYSTERESIS IN ShAPE MEMORY ALLOYS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1999年第3期12卷 235-240页

作者： Gong, S.K. Xu, h.b. beijing Univ of Aeronautics and Astronautics Beijing China

The pseudoelastic hysteresis loop associated with phase equilibrium and the stress relaxation on the yield line were investigated, and the theoretical description was confirmed by deformation controlled load-deformation measurements on CuZnAl single crystals. It was found that in a loading-unloading process, the states of shape memory alloys run through a hysteresis loop, and the points that trigger the internal yield and recovery inside the pseudoelastic hysteresis loop define a line that traverses the hysteresis loop from the upper left to the lower right corner. This line was interpreted as a line of unstable phase equilibrium according to the thermodynamic arguments, which determines also the tendency for stress relaxation on the yield line section and for a stress growth on the recovery line section.

关键词： Aluminum copper alloys hysteresis Stress relaxation

IMPROVED COhESIVE ZONE MODEL AND ITS APPLICATION IN INTERFACE CONTACT ANALYSIS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2008年第4期21卷 295-302页

作者： Y. Wang J. Chen h.b. Li National Die ＆ Mold CAD Engineering Research Center Shanghai Jiaotong University Shanghai 200030China

An improved interface cohesive zone model is developed for the simulation of interface contact, under mixed-mode loading. A new debonding initiation criterion and propagation of debonding law, taking into account the pressure stress influence on contact shear strength, is proposed. The model is implemented in a finite-element program using subroutine VUINTER of AbAQUS Explicit. An edge-notch four-point bending process and laminated vibration damping steel sheet punch forming test are simulated with the improved model in AbAQUS Explicit. The numerical predictions agree satisfactorily with the corresponding experimental results.

关键词： Cohesive zone model Mixed mode Damage criterion Contact stress

MICROSTRUCTURE AND MEChANICAL PROPERTIES OF Mg-Li ALLOY WITh Ca ADDITION

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 355-361页

作者： h.b. Li G. C. Yao Z.Q. Guo Y.h. Liu h.J. Yu h.b. Ji School of Materials ＆ Metallurgy Northeastern University Shenyang 110004 China

Mg-9wt%Li-2wt%Zn alloy was prepared and studied in this article. The addition of Ca to the alloy from 0.1wt% to 1wt% can refine the α-Mg and the best effect of refinement occurs when Ca content is 0.4wt%-0.5wt%. The billets can be rolled to thin sheets at room temperature, from which it is obvious that the addition of Ca improves alloys ormalin. while it decreases with the excess addition of Ca. The results also show that the ultimate tensile strength （UTS） and yield strength （YS） of the alloy with lwt% Ca may rise by 28% and 25%, respectively, however, the elongation decreases. It is clarified that the adsorption of proper Ca on the grain boundaries refines α-Mg and improves the tensile properties, but the presence of excess Ca and stable Ca2Mg6Zn3phase worsens the elongation.

关键词： calcium Mg-Li-Zn alloy cold rolling microstructure tensile property

Current Status in Layered Ternary Carbide Ti_3SiC_2,a Review

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2009年第1期25卷 1-38页

作者： h.b. Zhang Y.W. bao Y. C. Zhou Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

This article provides a review of current research activities that concentrate on Ti3SiC2. We begin with an overview of the crystal and electronic structures, which are the basis to understand this material. Followings are the synthetic strategies that have been exploited to achieve, and the formation mechanism of Ti3SiC2. Then we devote much attentions to the mechanical properties and oxidation/hot corrosion behaviors of Ti3SiC2 as well as some advances achieved recently. At the end of this paper, we elaborate on some new discoveries in the Ti3SiC2 system, and also give a brief discussion focused on the ＂microstructure -property＂ relationship.

关键词： Layered ternary ceramics Ti3SiC2 Mechanical properties Oxidation

FEM ANALYSIS OF ThERMAL STRESSES IN GRADIENT ThERMAL bARRIER COATINGS PRODUCED bY Eb-PVD

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2001年第6期14卷 493-496页

作者： h.b. Guo, h.b. Xu and S.K. Gong (Department of Materials Science & Engineering, beijing University of Aeronautics and Astronautics, beijing 100083, China) Dept. of Mat. Sci. and Eng. Beijing Univ. of Aero. and Astron. Beijing 100083 China

Gradient thermal barrier coatings (GTbCs) produced by co-deposition of mixtures ofAl-Al2 O3-YSZ onto metallic bond coat exh.b.ted longer lifetimes than the two-layeredTbCs. The finite element method (FEM) numerical models were used to investigatestress and strain states in the GTbCs and traditional two-layered TbCs as they cooledto 750℃ from a stress-free state at 850℃.

关键词： Eb-PVD gradient thermal barrier coating finite element method

COMPOSITION TRIANGLE DIAGRAMS OF Ni-Mn-Ga MAGNETIC ShAPE MEMORY ALLOYS

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2006年第3期19卷 171-175页

作者： Y.F. Wang J.M. Wang C.b. Jiang h.b. Xu School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

A statistical work has been done to collect the composition ranges of Ni-Mn-Ga alloys exh.b.ting different structures and martensite start temperature （M,）, large magnetostrain or the co-existence of magnetic and structural transitions. The alloys with five-layered （5M）, seven-layered （7M） modulated and non-modulated （T） martensitic structures were mapped in the graph. An empirical formula has been presented to reflect the effect of elements nickel （Ni ）, manganese （ Mn ） and gallium （Ga）, on the martensite start temperature （M3）. The martensitic structure is sensitive to the composition and the martensitic transformation temperature is most drastically affected by the Ni content. The alloys with large magnetostrain or co-existence effect of the magnetic and structural transitions were also listed in a limited area.

关键词： Ni2MnGa alloy martensitic transformation magnetic shape memory alloy

EFFECT OF COPPER ADDITION ON MEChANICAL PROPERTIES OF 4Cr16Mo

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 43-49页

作者： h.M. Geng X.C. Wu Y.A. Min h.b. Wang h.K. Zhang College of Materials Science and Engineering Shanghai University Shanghai 200072 China Special Steel branch Baoshan Iron ＆ Steel Co Ltd Shanghai 200940 China

Experiments conducted to determine the effect of copper addition on the machinability of plastic mold steel, 4Cr16Mo, were presented. The machinability of mold steel 4Cr16Mo was visibly improved by adding Cu. The top wear of 4Cr16Mo with copper was less than that without copper. The Cu-rich phase had the effect of a lubricant and the heat conductivity, which reduced cutting-tool wear, improved machinability, and increased the service life of the cutting-tool. Increasing of copper addition decreased the hot-working character of 4Cr16Mo. The optimal hot-working parameters for 4Cr16Mo with copper were determined by the tensile test and the compression test. The rate of deformation should be adopted as 0.6 s-1. The heating-up temperature, initial forging temperature, and terminal forging temperature were 1200℃, 1150℃, and 950℃, respectively.

关键词： Machinability Cutting-tool hot-shortness Cu-rich phase

ThE INFLUENCE OF Mo DIFFUSION ON ThE ThERMAL bEhAVIOR OF TbCs ON Ni_3Al bASED ALLOY IC-6

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2002年第1期15卷 45-48页

作者： D.b. Zhang S.K. Gong h.b. Xu Y.F. han Dept. of Mat. Sci. and Eng. Beijing Univ. of Aero. and Astron. Beijing 100083 China

Conventional two-layered structure thermal barrier coatings (TbCs) were prepared onto γ'-Ni3Al based alloy IC-6 by electron beam physical vapor deposition (Eb-PVD). Isothermal oxidation and thermal cycling tests were carried out to investigate the effect of Mo content at the interface between bond coat and ceramic top coat caused by diffusion. It has been found that the alloy coated with TbCs presented the lowest oxidation weight gain value for the reason that the ceramic top coat in TbC system can effectively stop Mo oxides evaporating. The life time of TbCs has close relation with Mo content at the interface between the bond coat and top coat. Spaliation of ceramic top coat occurred during thermal cyclic testing when Mo atoms accumulated at the interface up to certain amount to decline the combination between the bond coat and top coat.

关键词： Eb-PVD thermal barrier coatings (TbCs) thermal cyclic diffusion