检索结果-内蒙古大学图书馆

Prediction of Large Structure Welding Residual Stress by Similitude Principles

Journal of Materials Science & technology 2009年第6期25卷 861-864页

作者： Shude Ji Liguo Zhang Xuesong Liu Jianguo Yang School of Aerospace Engineering Shenyang Institute of Aeronautical Engineering Shenyang 110034 China State Key Laboratory of Advanced Welding Production Technology Harbin Institute of Technology Harbin 150001 China

On basis of the similitude principles, the conception of virtual simulative component and the auxiliary value of welding residual stress, which is deduced by the welding conduction theory, the relation of the welding residual stress between the simulative component and the practical component was attained. In order to verify the correctness of the relation, the investigation was done from the view of the welding experiment and the numerical simulation about the simulative component and the practical component. The results show that the distribution of welding residual stress of the simulative component is the same as that of the practical component. The ratio of welding residual stress attained by the experiment or the simulation method between the practical runner and the simulative component was compared with the ratio obtained by the similitude principles. Moreover, the error is less than 10%. This provides a new idea to predict the welding stress distribution of large practical structure by the contractible physical model, which is important for the welding experiment and the numerical simulation.

关键词： Similitude principles Large welding structure Simulative components Welding residual stress

来源：评论

学校读者我要写书评

暂无评论

Effects of Al Addition on the Microstructure and Properties of Nb/Nb_5Si_3 in situ Composites Fabricated via Spark Plasma Sintering

引用

Journal of Wuhan University of technology(Materials Science) 2014年第5期29卷 1036-1038页

作者：龙文元 YAO Junping FU Zhengyi College of Aeronautical Manufacuring Engineering Nanchang Hangkong University State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology

Dense Nb/Nb5Si3 composites were fabricated via spark plasma sintering technology using Nb, Si, and Al elemental powders as raw materials. The microstructttres of the synthesised composites were analyzed through scanning electron microscopy, X-ray diffraction, and electron probe microanalysis. The results show that the composites consisted of residual Nb particle phase and Nb5Si3 phase. The microstructure of the Nb/ Nb5Si3 in situ composites was evidently affected by Al addition, which prompted the formation of the Al3Nb10Si3 phase. In addition, the Rockwell hardness of the composites decreased with the increase in AI additions. The Rockwell hardness of Nb-20Si is 60HRC, which decreased to approximately 52.7 HRC when the Al content increased to 15 at%. The oxidation resistance of the Nb/NbsSi3 in situ composites significantly improved with the increase in Al addition.

关键词： spark plasma sintering Nb/Nb5Si3 composites oxidation resistance microstructure

来源：评论

学校读者我要写书评

暂无评论

Effects of defect states on the performance of CuInGaSe_2 solar cells

引用

Journal of Semiconductors 2014年第2期35卷 76-81页

作者：万福成汤富领薛红涛路文江冯煜东芮执元 State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials Department of Materials Science and EngineeringLanzhou University of Technology Science and Technology on Surface Engineering Laboratory Lanzhou Institute of Physics

Device modeling has been carried out to investigate the effects of defect states on the performance of ideal CulnGaSe2 （CIGS） thin film solar cells theoretically. The varieties of defect states （location in the band gap and densities） in absorption layer CIGS and in buffer layer CdS were examined. The performance parameters： open-circuit voltage, short-circuit current, fill factor, and photoelectric conversion efficiency for different defect states were quantitatively analyzed. We found that defect states always harm the performance of CIGS solar cells, but when defect state density is less than 10 14 cm-3 in CIGS or less than 10 18 cm-3 in CdS, defect states have little effect on the performances. When defect states are located in the middle of the band gap, they are more harmful. The effects of temperature and thickness are also considered. We found that CIGS solar cells have optimal performance at about 170 K and 2 μm of CIGS is enough for solar light absorption.

关键词： device modeling defect states solar cell conversion efficiency

来源：评论

学校读者我要写书评

暂无评论

Numerical simulation for the investment casting process of a large-size titanium alloy thin-wall casing

引用

Progress in Natural Science:Materials International 2018年第4期28卷 520-528页

作者： Pan Tao Heng Shao Zhijun Ji Hai Nan Qingyan Xu Key Laboratory for Advanced Materials Processing Technology Ministry of Education School of Materials Science and Engineering Tsinghua University Beijing Institute of Aeronautical Materials

To optimize the investment casting process when producing high quality large-size titanium alloy thin-wall components is a time-consuming job due to the complicated metallurgical process. Numerical simulation is a high-efficiency method compared with trial and error, and therefore is introduced to the investment casting process optimization to shorten the new product development cycle and reduce the production cost. In this study, weakly compressible model(WCM) and ununiformed finite difference mesh(UFDM) was developed to reduce the memory consumption and ensure the simulation efficiency. The precision of the WCM and UFDM were verified by numerical simulation of cavity heat convection in a square cavity and hydraulics simulation of centrifugal filling in a transparent cavity. The numerical simulation of the investment casting process of a titanium alloy thin-wall casing under different process conditions was accomplished using a self-developed software, and the distribution characteristics of potential shrinkage defects were predicted. It was found that the predicted defects in the titanium alloy casing matched well with the actual X-ray experimental results. For the components investigated in this paper, more numerical simulation results show that the centrifugal casting process with respect to gravity casting had no obvious improvements in the concentrated shrinkage defects, and the gravity casting process can be more reasonable from the engineering point of view.

关键词： Titanium alloy Investment casting Numerical simulation Finite difference method Non-uniform mesh

来源：评论

学校读者我要写书评

暂无评论

Microstructure and mechanical properties at elevated temperature of Mg-Al-Ni alloys prepared through powder metallurgy

引用

Journal of Materials Science & technology 2017年第9期33卷 947-953页

作者： Legan Hou Bingcheng Li Ruizhi Wu Lin Cui Peng Ji Ruiying Long Jinghua Zhang Xinlin Li Anping Dong Baode Sun Key Laboratory of Superlight Materials & Surface Technology Ministry of EducationHarbin Engineering University College of Civil and Architectural Engineering Heilongjiang Institute of Technology Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming Shanghai Jiao Tong University

Mg-Al-Ni alloys were prepared by powder metallurgy, and their microstructure and elevated temperature mechanical properties were investigated. Results indicate that, in addition to α-Mg matrix, both coarse Al;Ni;particles and fine Al Ni nano-particles exist in the Mg-Al-Ni alloys. The strength at 150?C is improved with the increase in Ni content. Mg-18.3Al-8Ni alloy possesses a compressive strength of234.7 MPa and a yield strength of 146.5 MPa. Plasticity is also improved with a low concentration of Ni. Mg-11.3Al-2Ni alloy possesses a compression ratio of 17.3%. The phases of Al;Ni;and Al Ni in the alloys block the movements of grain boundaries and dislocations during the deformation at elevated temperature. The existence of Al Ni phase provides a non-basal slip system, leading to the improvement in plasticity. Finally, the formation mechanism of Al-Ni phases in the process is discussed with thermodynamics and kinetics.

关键词： Mg-Al-Ni alloy Powder metallurgy Al3Ni2 AlNi

来源：评论

学校读者我要写书评

暂无评论

Cluster banding heat source model

引用

China Welding 2006年第3期15卷 55-58页

作者：张利国姬书得杨建国方洪渊李雅范 Institute of Astronautical Technology Shenyang Institute of Aeronautical Engineering State Key Laboratory of Advanced Welding Production Technology Harbin Institute of Technology

Concept of duster banding heat source model is put forward for the problem of overmany increment steps in the process of numerical simulation of large welding structures, and expression of cluster banding heat source model is deduced based on energy conservation law. Because the expression of cluster banding heat source model deduced is suitable for random weld width, quantitative analysis of welding stress field for large welding structures which have regular welds can be made quickly.

关键词： cluster banding heat source numerical simulation welding residual stress

来源：评论

学校读者我要写书评

暂无评论

Theoretical study and numerical simulation of the stress fields of the Al_2O_3 joints brazed with composite filler materials

引用

China Welding 2006年第3期15卷 74-78页

作者：杨建国姬书得方洪渊 State Key Laboratory of Advanced Welding Production Technology Harbin Institute of Technology Institute of Astronautical Technology Shenyang Institute of Aeronautical Engineering

Non-linear finite element code MSC. Marc was utilized to analysis the field of stress of the Al2O3 joints brazed with composite filler materials. The properties of the filler materials were defined by using the mixing law, method of Mori-Tanaka and theory of Eshelby to ensure the accuracy and reliability of results of finite element method （FEM）. The results show stress in brazed beam is higher than that in base material. The maximal stress can be found in the interface of joint. And the experimental results show that the shear strength of joints increases from 93.75 MPa （ Al2O3p Ovol. % ） to 135.32 MPa （ Al2O3p 15vol. % ） when composition of titanium is 3wt% in the filler metal.

关键词： composite filler materials brazed joints finite element method residual stress

来源：评论

学校读者我要写书评

暂无评论

Effects of heat transfer in a growing particle layer on microstructural evolution during solidification of colloidal suspensions

引用

Chinese Physics B 2021年第2期30卷 540-548页

作者： Jia-Xue You Yun-Han Zhang Zhi-Jun Wang Jin-Cheng Wang Sheng-Zhong Liu Key Laboratory of Applied Surface and Colloid Chemistry Ministry of EducationShaanxi Key Laboratory for Advanced Energy DevicesShaanxi Engineering Laboratory for Advanced Energy TechnologyInstitute for Advanced Energy MaterialsSchool of Materials Science and EngineeringShaanxi Normal UniversityXi'an 710119China State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710072China

Heat transfer is the foundation of freezing colloidal suspensions and a key factor for the interface ***,how the thermal conductivity of particles affects freezing microstructural evolution remains *** in this work,a mathematical model is built up to investigate thermal interactions among a growing particle layer,pulling speeds,and the freezing interface under a thermal *** are conducted to confirm the tendency predictions of the *** the increase of pulling speeds,the drifting distance of the freezing interface increases and the time to finish drifting *** the thermal conductivity of particles(k_(p))is smaller than that of the surrounding(kw),the freezing interface tends to go forward to the warm ***,the freezing interface tends to go back to the cold side when the thermal conductivity of particles is larger than that of the surrounding(α=k_(p)/k_(w)>1).It originates from the shape of the local freezing interface:convex(α<1)or concave(α>1).These morphological changes in the local interface modify the premelting drag force F_(f).Whenα<1,F_(f)decreases and the freezing morphology tends to be the frozen ***α>1,F_(f)increases and the freezing morphologies tend to be ice *** understandings of how the thermal conductivity of particles affect microstructural evolution may optimize the production of freeze-casting materials and their structural-functional properties.

关键词： solidification colloidal suspensions heat transfer microstructural evolution

来源：评论

学校读者我要写书评

暂无评论

Powder injection molding of Fe-Ni soft magnetic alloys

引用

Rare Metals 2006年第z1期25卷 440-444页

作者： DUAN Bohua QU Xuanhui QIN Mingli GUO Shibo State Key Laboratory for Advanced Metals and Materials School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijing 100083China Jiangxi Key Laboratory of Surface Engineering Jiangxi Science and Technology Normal UniversityNanchang 330013China

With miniaturization and complication of the shape of electronic devices in recent years,powder injection molding(PIM)seems to be a suitable process for fabricating the higher performance soft magnetic *** this paper,high quality Fe-50Ni soft magnetic alloy was fabricated by PIM with carbonyl iron and nickel,and the effect of sintering process on its microstructure and magnetic properties were *** mechanical and magnetic properties can be obviously improved by increasing the sintering temperature or using the hydrogen atmosphere instead of high vacuum,which causes by the increase of grain size and the *** the optimum sintering conditions,the PIM Fe-50Ni soft magnetic alloy with high properties are obtained,whose relative density,tensile strength,B_(m),H_(c),μ_(m)are 97%,465 MPa,1.52 T,16.62 A·m^(-1),42.5 mH·m^(-1),respectively.

关键词： powder injection molding soft magnetic alloy sintering

来源：评论

学校读者我要写书评

暂无评论

Decorating hole transport material with −CF_(3) groups for highly efficient and stable perovskite solar cells

引用

Journal of Energy Chemistry 2021年第11期30卷 523-531,I0012页

作者： Bin Li Yuan Cai Xia Tian Xiaozhong Liang Da Li Zheng Zhang Sijing Wang Kunpeng Guo Zhike Liu Ministry of Education Key Laboratory of Interface Science and Engineering in Advanced Materials Taiyuan University of TechnologyTaiyuanShanxi 030024China Key Laboratory of Applied Surface and Colloid Chemistry Ministry of EducationShaanxi Engineering Lab for Advanced Energy TechnologySchool of Materials Science and EngineeringShaanxi Normal UniversityXi’anShaanxi 710119China

The hole transport material (HTM) plays an extremely important role to determine the power conversion efficiency (PCE) and the stability of perovskite solar cells (PSCs). Herein, we report an effective strategy to improve the performance of HTMs by introducing −CF_(3) groups via the rational decorative mode. Upon direct attachment or nonconjugated alkoxyl bridging of −CF_(3) groups on the terminal diphenylamines, the resulting molecular HTMs, i.e., 2,7-BCzA4CF_(3) and 2,7-BCzA4OCCF_(3), show distinct properties. Compared with 2,7-BCzA4CF_(3), the nonconjugated alkoxyl bridging −CF_(3) group-based 2,7-BCzA4OCCF_(3) exhibits better thermal stability, hydrophobicity, and a dramatically upgraded hole mobility by 135.7-fold of magnitude to 1.71 × 10^(−4) cm^(2) V^(−1) S^(−1). The PSCs with 2,7-BCzA4OCCF_(3) as HTM exhibit an PCE of up to 20.53% and excellent long-term stability, maintaining 92.57% of their performance for 30 days in air with humidity of 30% without encapsulation. This work provides beneficial guidelines for the design of new HTMs for efficient and stable PSCs.

关键词： Perovskite solar cell Hole transport material Decorating group Trifluoromethyl group Nonconjugated alkoxyl bridging

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：