检索结果-南通市图书馆

Microstructures and constituents of super-high strength aluminum alloy ingots made through LFEC process

在线全文

学校读者我要写书评

暂无评论

China Foundry 2007年第4期4卷 280-283页

作者： WANG Shuang ZUO Yu-bo cui jian-zhong College of Software Northeastern University Shenyang 110004 China Keb Lab of EPM Northeastern University Shenyang 110004 China

Ingots of a new super-high strength Al-Zn-Mg-Cu-Zr alloy were produced respectively by low frequency electromagnetic casting(LFEC)and by conventional direct chill(DC)casting process.Microstructure and constituents of the ingots were studied.The results indicated that the LFEC process significantly refines microstructure and constituents of the alloy,and to some extent,decreases the area(or volume)fraction of constituents and eutectic structure precipitated at grain boundaries.But,no difference in the type of constituents was observed between LFEC and DC ingots.The results also showed LFEC process can improve the as-cast mechanical properties.

关键词：铝锌镁铜锆合金低频率电磁领域 DC流铸特种铸造

Effects of High Magnetic Field on Microstructure and Properties of Low Aspect Ratio Bi_2Sr_2CaCu_2O_x/AgMg Wire

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2012年第S2期19卷 1048-1053页

作者： LIU Xiao-tao SCHWARTZ Justin cui jian-zhong The Key Lab of Electromagnetic Processing of Materials of Ministry Education Notheastern University Department of Materials Science of Engineering North Carolina State University

Here,we report the effect of an 8 T magnetic field on the microstructure and properties of a reetangular Bi_2Sr_2CaCu2Ox/AgMg(Bi2212/AgMg) conductor with low aspect ratio.The magnetic field was applied during split melt process with the field direction perpendicular and parallel to the wide surface of the conductors.After heat treatment, the conductors were electrically characterized using four-point critical current measurements as a function of magnetic field and magnetic field orientation relative to the conductor.The superconducting transition and magnetization hysteresis were measured using a SQUID magnetometer.The microstructure was characterized using scanning electron microscopy. It was found that the presence of magnetic field during split melt processing enhances the electrical transport and magnetic behavior.The magnetic field increases the Bi2212 grains alignment and long range texture within filaments and bridges between filaments by textured growth of Bi2212 phase.

关键词： High magnetic field Bi2212 Critical current density Texture

The Magnetic Field Interference in Dual-Ingot Low Frequency Electromagnetic Continuous Casting

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2012年第S2期19卷 987-990页

作者： WANG Gao-song ZHAO Zhi-hao cui jian-zhong Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern University

The magnetic field interference was studied by numerical simulation and experimental examination during dual-ingot low-frequency electromagnetic casting process.By using ANSYS software package to mesh and compute,the magnetic field distribution of semi-continuous casting mold region was simulated.The calculated results were verified with the experimental ones and the effects of current direction,shield,silicon sheet and the coil distance on the distribution of magnetic field and ingot were observed.The result indicated that:regardless of current direction,the magnetic field interference among coils appears and the magnetic flux density weakens in the neighbor part of coils. When the current direction of adjacent coils is opposite,the magnetic intensity in ingots is stronger than that of in the same direction.As the distance between coils increases,the magnetic field reduction generated by interference decreases. The magnetic field interference can be alleviated by setting silicon steel sheets or shield.

关键词： dual-ingot casting electromagnetic field LFEC numerical simulation

Study on As-Cast Structure of DC Casting Aluminum Alloy Under Dual Frequency Electromagnetic Field

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2012年第S1期19卷 265-268页

作者： ZHAO Zhi-hao WANG Gao-song cui jian-zhong Key Lab.of EPM Ministry of EducationChinaNortheastern University

The as-cast structures of semi-continuous casting aluminum alloy under dual-frequency electromagnetic field were experimental investigated.The results showed that the electromagnetic fields with different frequency have different function for improving the cast structure of aluminum alloy casting.Imposing medium frequency electromagnetic field can change the surface morphology of melt pool in the casting process,increase the height of melt meniscus,improve the ingot's surface quality,and reduce the thickness of surface segregation.The low frequency electromagnetic field is most obvious to as-cast structure improvement effect because of its high permeability in conductance material.Imposing low-frequency electromagnetic field can change flow pattern and temperature field in the melt,strengthen the heat transfer and mass transfer in the melt,decrease the depth of the sttmp and reduce the temperature gradient.Thus,the as-cast structures are greatly refined,which can lead to the fine equiaxed as-cast structures throughout the cross-section of the ingot.

关键词： dual frequency electromagnetic field semi-continuous casting aluminum alloy as-cast structure

Effect of c-Jun NH2-terminal kinase-mediated p53 expression on neuron autophagy following traumatic brain injury in rats

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2012年第11期125卷 2019-2024页

作者： HONG Ming-yan GAO Jun-ling cui jian-zhong WANG Kai-jie TIAN Yan-xia LI Ran WANG Hai-tao WANG Huan Department of Surgcry Hebei Medical University Shijiazhuang Hebei 050017 China School of Basic Medical Sciences Hebei United University Tangshan Hebei 063000 China Worker＇s Hospital Tangshan Hebei 063000 China

Background Activation of c-Jun NH2-terminal kinase （JNK） has been implicated in neuron apoptosis as well as autophagy in response to various stressors after traumatic brain injury （TBI）. However, the underlying molecular pathway remains unclear. Our study assessed whether JNK-mediated p53 phosphorylation might be an important mechanism for enhancing neuron autophagy in response to TBI. Methods A total of 186 male Sprague-Dawley （SD） rats （300-350 g） were used in this study. By randomized block method rats were randomly divided into four groups： sham-operated （n=46）, TBI （n=60）, TBI ＋ dimethyl sulfoxide （DMSO）（n=40）, and TBI ＋ SP600125 （n=40）. JNK was treated with SP600125, a specific JNK inhibitor. JNK, p-P53, Beclin-1, damage-regulated autophagy modulator （DRAM） and p-bcl-2 were evaluated by Western blotting analysis. The cellular localization and expression of Beclin-1 and DRAM was observed by immunofluorescence and immunohistochemistry, and the expression of Beclin-l-Bcl-2/Bcl-xL complexes was evaluated by immunoprecipitation. Multiple-group comparisons were conducted using analysis of variance （ANOVA）. P values of less than 0.05 were considered statistically significant. Results It was observed that the expression of JNK, p-P53, Beclin-1, DRAM and p-bcl-2 was increasing after TBI, and the expression of Beclin-1 and DRAM was mainly located in the cytoplasm of neurons. But these were significantly inhibited in SP600125 group compared with sham group and TBI＋SP600125 group （P 〈0.05）. The expression of Beclin-l-Bcl-2/Bcl-xL complexes was reduced after TBI. Conclusion JNK-mediated p53 phosphorylation might be an important mechanism for enhancing neuron autophagy in response to TBI.

关键词： brain injuries, autophagy c-Jun NH2-terminal kinase p53 damage-regulated autophagy modulator

Influence of a Pulse Magnetic Field on the Size and Distribution of Primary Si in Hypereutectic Al-23%Si Alloy

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2012年第S1期19卷 301-304页

作者： BAN Chun-yan jianG Dan-dan LIU Lian cui jian-zhong Key Laboratory of National Education Ministry for Electromagnetic Processing of Materials Northeastern University

A pulse magnetic field(PMF)was applied on the hypereutectic A1-23%Si alloy of different temperature range(830-780 ℃,830-730 ℃,830-700 ℃,780-700 ℃,730-700 ℃)during its solidification processing.The influence of pulse magnetic field on the size and distribution of primary Si was studied.The results show that,the primary Si is very coarse strip,distributs non-unifromly and gathers at the edge of the sample when the alloy solidifies under the condition of no PMF.By applying PMF can significantly refine the primary Si,and make the primary Si distribute uniformly.There has no significant effect on the refinement of primary Si when PMF applied from 830 ℃ to 780 ℃,indicating that PMF has no outstanding effect on the high temperature liquid metal.Applying PMF from 50 ℃ above the liquidus to 30 ℃ below the liquidus(i.***.from liquid to the initial nucleation stage)can get the best refinement result.The refining mechanism of the pulse magnetic field on the solidification structure of Ai-23%Si alloy was discussed,

关键词： Al-Si alloy PMF primary Si Size distribution

Study on the Grain Refinement of an Al-Zn-Mg-Cu Alloy Prepared by LFEC Process

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2012年第S1期19卷 273-276页

作者： ZUO Yu-bo ZHAO Zhi-hao ZHANG Hai-tao QIN Ke cui jian-zhong Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern University

Low frequency electromagnetic casting(LFEC)process has been developed for years with the application of an induction coil outside the conventional direct chill(DC)casting mould.It has been demonstrated that the LFEC process has a significant grain refining effect on aluminium alloys.However,how it refines the microstructure is still not clearly understood.In the present work,the temperature measurement were carried out to study the temperature field during casting and to understand the mechanism of the grain refining effect of the LFEC process.The results showed that in contrast to the conventional DC casting process,during the LFEC process,the liquid melt flowing from the launder into the mould is cooled with very high cooling rate directly to 3-6 ℃ below the liquidus and the temperature field of the entire melt in the mould and the hot top is quite uniform,which results in enhanced heterogeneous nucleation and improved survival rate of the nuclei.This is believed to be the main reason why the LFEC process can significantly refine the grain size of aluminium alloys.

关键词： Al-Zn-Mg-Cu alloy grain refinement low frequency electromagnetic casting DC casting temperature measurement

The Effect of the Combination of Electromagnetic Field on the Surface Quality and Inner Structure of HDC Casting Al 3004 Ingot

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2012年第S1期19卷 322-326页

作者： ZHU Qing-feng ZHAO Zhi-hao ZUO Yu-bo WANG Xiang-jie cui jian-zhong Key Laboratory of Electromagnetic Processing of Materials Ministry of EducationNortheastern University

The combination of electromagnetic field is applied in the Horizontal Direct Chill(HDC)casting process to produce 3004 aluminum alloy ingot.The effect of combination of electromagnetic field on the ingot surface quality and inner structure was investigated by macro and micro-structure observation.The results show that the combination of electromagnetic field can improve the ingot surface quality and inner structure effectively.The thickness of segregation layer decreased with the application of combination of electromagnetic field.In addition,the combination of electromagnetic field can effectively improve the as-casting structure.Under the function of combination of electromagnetic field,coarse columnar grains transfer to fine equiaxed grains.

关键词： combination electromagnetic field 3004 aluminum alloy horizontal continuous casting as-cast structure surface quality

Effect of mould material on aluminum alloy ingot quality under low frequency electromagnetic casting

在线全文

学校读者我要写书评

暂无评论

China Foundry 2006年第4期3卷 288-292页

作者： LI jian-chao cui jian-zhong WANG Bao-feng MA Yong-lin Northeastern University Shenyang 110004 Inner Mongolia University of Science and Technology Baotou 014010 Northeastern University Shenyang 110004 Inner Mongolia University of Science and Technology Baotou 014010

With the aid of ANSYS software, the effect of different mould external part materials on magnetic flux density and electromagnetic body force in the liquid aluminum was investigated. Calculated results showed that magnetic flux density and electromagnetic body force in the aluminum melt are greatly increased when the external part of mould is made from A3 steel. A low-frequency electromagnetic casting 6063 aluminum alloy experiment was conducted in the laboratory with the current value of 120 A and frequency value of 15 Hz. The experiment showed that the microstructure and surface quality of ingots with mould outer part made from A3 steel under low-frequency electromagnetic field are better than that of ingots with mould outer part made from austenitic stainless steel. The surface of the ingots with mould outer part made from A3 steel is smooth and free from exudations and cold shut defects. The as-cast microstructure consists of fine, uniformly distributed equiaxed grains.

关键词： Low-frequency electromagnetic casting finite element method aluminum alloy mould material