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Simulations of deformation and damage processes of SiCp/Al composites during tension

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Journal of Materials Science & Technology 2018年第4期34卷 627-634页

作者： J.F.zhang X.X.zhang q.z.wang B.L.Xiao z.Y.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China

The deformation, damage and failure behaviors of 17 vol.% SiCp/2009AI composite were studied by micro- scopic finite element （FE） models based on a representative volume element （RVE） and a unit cell. The RVE having a 3D realistic microstructure was constructed via computational modeling technique, in which an interface phase with an average thickness of 50 nm was generated for assessing the effects of interracial properties. Modeling results showed that the RVE based FE model was more accurate than the unit cell based one. Based on the RVE, the predicted stress-strain curve and the fracture morphology agreed well with the experimental results. Furthermore, lower interface strength resulted in lower flow stress and ductile damage of interface phase, thereby leading to decreased elongation. It was revealed that the stress concentration factor of SiC was -2.0： the average stress in SiC particles reached -1200 MPa, while that of the composite reached -600 MPa.

关键词： Metal matrix composites (MMCs) Fracture Finite element (FE) analysis Interfacial strength Tensile strength Representative volume element (RVE)

STUDY OF THE INFLUENCE OF pH ON THE ELECTROCRYSTALLIzATION OF zINC

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Acta Metallurgica Sinica(English Letters) 2005年第4期18卷 497-504页

作者： z. zhang W.H. Leng J. q. zhang Department of Chemistry Zhejiang University Hangzhou 310027 China State Key Laboratory for Corrosion and Protection Institute of Metal Reseach The Chinese Academy of Sciences Shenyang 110016 China

The influence of pH value of the electrolyte solution on the zinc electroplating process was studied by means of cyclic voltammetry and chronoamperometry approaches. The results shown that, under this experimental conditions and at high overpotentials, the nucleation of zinc is instantaneous, and the nuclear densities N increase with the overpotentials. While at low potentials, no distinguished nucleation current can be observed. High pH promotes the deposition either by drifting the initial depositing potential positively, or by increasing the depositing current through the change of the total charge of the adsorption process qads, i.e., thevstructure of electrochemical double layer.

关键词： zinc electroplating nucleation growth mechanism

Effect of Ni Content on Mechanical Properties and Corrosion Behavior of Al/Sn－9zn－xNi/Cu Joints

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Journal of Materials Science & Technology 2012年第9期28卷 844-852页

作者： M.L.Huang N.Kang q.zhou Y.z.Huang Key Laboratory of Liaoning Advanced Welding and Joining Technology School of Materials Science&EngineeringDMian University of TechnologyDalian 116024China

The effects of Ni content on the microstructure and the wetting behavior of Sn-9zn-xNi solders on Al and Cu substrates, as well as the mechanical properties and electrochemical corrosion behavior of Al/Sn-9zn-xNi/Cu solder joints, were investigated. The microstructure of Sn-gzn-xNi revealed that tiny zn and coarsened Ni5zn21 phases dispersed in theβ-Sn matrix. The wettability of Sn-9zn-xNi solders on Al substrate was much better than that on Cu substrate. With increasing Ni content, the wettability on Cu substrate was slightly improved but became worse on Al substrate. In the Al/Sn-9zn-xNi/Cu joints, an Al4.2Cu3.2zn0.7 intermetallic compound （IMC） layer formed at the Sn-gzn-xNi/Cu interfaces, while an Al-zn-Sn solid solution layer formed at the Sn-9zn-xNi/Al interface. The mixed compounds of Ni3Sna and Al3Ni dispersed in the solder matrix and coarsened with increasing Ni content, thus leading to a reduction in shear strength of the Al/Sn-9zn- xNi/Cu joints. Al particles were segregated at both interfaces in the solder joints. The corrosion potentials of Sn-9zn-xNi solders continuously increased with increasing Ni content. The Al/Sn-9zn-0.25Ni/Cu joint was found to have the best electrochemical corrosion resistance in 5% NaCl solution.

关键词： Al-Cu disslmilar-metal solder joint Sn-9zn-xNi Microstructure Mechanicalproperties Electrochemical corrosion Corrosion potential

MORPHOLOGY OF AMORPHOUS SILICA DURING ALUMINUM REACTIVE PENETRATION

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Acta Metallurgica Sinica(English Letters) 2000年第4期13卷 944-948页

作者： zhou, z. Gan, q.S. Ding, P.D. Chongqing Univ Chongqing China

The reduction of volume of silica glass during aluminum reactive penetration was observed experimentally. The liquid aluminum infiltrates easily into the cavities while the released silicon is solved in the liquid aluminum, and Al/Al2O3 composites could be obtained. The experimental results show that Al/Al2O3 composites can be transformed into Al2O3 grains by oxygen in the cavities of Al/Al2O3 composites during the longer penetration treatment. The formation of alumina is a sintering process, in which liquid aluminum, particulate alumina and oxygen play an important role. The transformtion process has shown that there is a relationship of σAl2O3-Al2O3 2O3-Al, where σAl2O3-Al2O3 is the grain boundary energy of alumina, and σAl2O3-Al is the interface energy between aluminum and alumina. The formation temperature by aluminum reactive penetration is much lower than that by sintering.

关键词： Alumina Aluminum Metallic matrix composites Morphology Silica

MICROSTRUCTURAL STUDY OF Fe-Cr-Al/Al COMPOSITE COATINGS DURING OXIDATION AND SULFIDATION AT 900℃

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Acta Metallurgica Sinica(English Letters) 2007年第2期20卷 87-94页

作者： z.L. zhang D.Y. Li X.q. Dong School of Material Science and Engineering Shenyang University of Technology Shenyang 110023 China

The microstructure of a composite coating system, which was composed of an inner layer of Fe-Cr-Al and an outer layer of aluminum, was studied after it was respectively oxidized and sulfurdized at elevated temperatures. Apart from the Al2O3 scale formed on the surface, the microstructure of the composite coatings exposed at 900℃ in air for 4h was a three-layer structure. The first layer consisted of a solid solution of Cr and Fe in α aluminum and an intermetallic compound FeAl3 while the second layer was a single phase of the aluminide and the third layer still remained the same appearance as the original Fe-Cr-Al coating. The microstructural observation of the specimen tested at 850-900℃ at low oxygen pressure and high sulfur pressure for 576h revealed that the surface coatings of the specimen had transformed into a duplex structure containing an outer layer and a thicker aluminide layer beneath. X-ray diffraction results showed that the out layer was composed of Al2S3 and Al2O3 and that AlCrFee was the main phase composition of the aluminide layer, with a few of Al2S3 and Al2O3 accompanied.

关键词： arc spray Fe-Cr-Al composite coating microstructure

Flux Adjustable Permanent Magnet Machines:A Technology Status Review

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Chinese Journal of Electrical Engineering 2016年第2期2卷 14-30页

作者： Hui Yang z.q.zhu Heyun Lin Wenqiang Chu School of Electrical Engineering Southeast UniversityNanjing210096China Department of Electronic and Electrical Engineering University of SheffieldSheffield SI 3JDU.K.

Flux adjustable permanent magnet machines(FAPMMs)are a novel type of permanent magnet(PM)machines which are able to flexibly adjust the field excitation flux linkage and offer the distinctive advantages of high power density and high *** have attracted ever-increasing interests and are promising candidate machines for electric vehicle,machine-tool and aircraft *** this paper,the state-of-the-art of various FAPMMs are comprehensively reviewed according to three means of flux-adjustment,*** adjusted by either auxiliary field windings or armature winding change,mechanically adjusted magnetic reluctances of flux paths,and memory machines by magnetizing/demagnetizing *** corresponding flux-adjustable principles and electromagnetic characteristics are systematically elaborated and quantitatively *** merits and demerits are highlighted,together with their recent developments.

关键词： Flux-adjustable hybrid excitation memory machine mechanical adjustment permanent magnet machine winding change

SYNTHESIS AND IDENTIFICATION OF CONDUCTING POLYANILINE DOPED WITH RARE EARTH CHLORIDE

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Acta Metallurgica Sinica(English Letters) 2000年第3期13卷 872-876页

作者： Yang, C.M. zhang, q.R. Fang, z. Central South Univ of Technology Changsha China

Polyaniline doped with rare earth chloride was synthesized in organic solvent and identified by elemental analysis and infrared spectroscopy. The experimental results show that there exists both doping and complexation at the same time in the resulting product. When pH4. Moreover, polyaniline doped with rare earth chloride exhibits better thermal stability than that doped with hydrochloric acid.

关键词： Chlorine compounds Composition Conductive materials Electric conductivity Organic polymers Rare earth compounds Synthesis (chemical)

Interaction specific binding hotspots in Endonuclease colicin-immunity protein complex from MD simulations

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Science China Chemistry 2013年第8期56卷 1143-1151页

作者： YAO XueXia JI ChangGe xie Daiqian zHANG John z.H. School of Chemistry and Chemical Engineering Nanjing University College of Engineering Nanjing Agricultural University State Key Laboratory of Precision Spectroscopy Department of PhysicsEast China Normal University Department of Chemistry New York University

The binding of Endonuclease colicin 9 (E9) by Immunity protein 9 (Im9) was found to involve some hotspots from helix III of Im9 on protein-protein interface that contribute the dominant binding energy to the *** the current work,MD simulations of the WT and three hotspot mutants (D51A,Y54A and Y55A of Im9) of the E9-Im9 complexes were carried out to investigate specific interaction mechanisms of these three hotspot *** changes of binding energy between the WT and mutants of the complex were computed by the MM/PBSA method using a polarized force field and were in excellent agreement with experiment values,verifying that these three residues were indeed hotspots of the binding *** decomposition analysis revealed that binding by D51 to E9 was dominated by electrostatic interaction due to the presence of the carboxyl group of Asp51 which hydrogen bonds to *** binding by hotspots Y54 and Y55,van der Waals interaction from the aromatic side chain of tyrosine provided the dominant *** comparison,calculation by using the standard (nonpolarizable) AMBER99SB force field produced binding energy changes from these mutations in opposite direction to the experimental *** hydrogen bond analysis showed that conformations sampled from MD simulation in the standard AMBER force field were distorted from the native state and they disrupted the inter-protein hydrogen bond network of the protein-protein *** current work further demonstrated that electrostatic polarization plays a critical role in modulating protein-protein binding.

关键词： protein-protein interaction binding hotspot mutation Endonuclease Colicin immunity protein MD simulation

ELECTROCHEMICAL NOISE ANALYSIS OF THE INFLUENCE OF THE zn^(2+)IONS CONCENTRATION ON zINC ELECTROPLATING

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Acta Metallurgica Sinica(English Letters) 2005年第2期18卷 137-144页

作者： z.zhang C.S.Wu q.Y.Cai F.H.Cao J.q.zhang DepartmentofChemistry ZhejiangUniversityHangzhou310027China DepartmentofChemistry ZhejiangUniversityHangzhou310027China／／StateKeyLaboratoryforCorrosionandProtectionInstituteofMetalResearchTheChineseAcademyofSciencesShenyang110016China

The influence of the concentration of zn2+ ions on zinc electroplating process was investigated by means of electrochemical noise (EN) and cyclic voltammetry methods in conjunction with the scanning electron microscopy (SEM) technique. It was found that the EN generated during the electroplating of dentritic or large polymeric zinc deposit has large potential oscillation amplitude and positive potential drift while the compact zinc deposit possesses small noise amplitude and little potential drift. With the change of rate determining step from diffusion-control through mixed-control to activation-control, the maximum relative energy obtained from wavelet analysis defined from the region with larger scales to those with smaller scales, and the EDP (relative energy distribution plot) can be us, as 'fingerprints' of EN to characterize the electroplating process and the deposit structure. The results also showed that electrochemical noise technique can give more information about the electrodeposit structure than other normal electrochemical measurements, such as linear potential sweep method and cyclic voltammetry technique.

关键词： zinc electroplating zinc ions concentration electrochemical noise electrodeposit structure