检索结果-南通市图书馆

Journal of Materials Science & Technology 2020年第22期54卷 172-179页

作者： yongxin jian Zhifu Huang Xiaoting Liu Jialin Sun jiandong Xing State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong UniversityXian710049China

Exploring the effective way to improve Fe2 B's toughness has always been the hot topic in the researches of Fe-B wear resistant alloys.In the present work,the effects of Cr on the microstructure,mechanical properties and lattice structure of directional Fe2 B have been investigated.The affecting mechanism of Cr addition has been discussed according to the experimental and first-principle calculation analysis.The results show Cr addition can improve the toughness of directional Fe2 B on the longitudinal sections perpendicular to(002) crystal plane,without sacrificing the hardness distinctly.The toughening mechanism by Cr substitution has been revealed:Cr addition enriches the electron density between the B atoms along [002] direction,contributing to the shrinkage of the bond length and the enhancement of the bond strength of B-B bonds.The obtained results provide insight into the intrinsic reason for toughening Fe2 B by Cr doping.

关键词： Directional Fe2B Cr addition Lattice evolution Toughening mechanism

The tribological behavior of a surface-nanocrystallized magnesium alloy AZ31 sheet after ultrasonic shot peening treatment

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2021年第4期9卷 1190-1203页

作者： jianyue Zhang yongxin jian Xuzhe Zhao Dean Meng Fusheng Pan Qingyou Han School of Engineering Technology Purdue UniversityWest LafayetteIN 47906USA State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049PR China Böllhoff Inc TroyMI 48084USA School of Automobile Chang’an UniversityXi’an 710064PR China College of Materials Science and Engineering Chongqing UniversityChongqing 400045PR China

A magnesium alloy AZ31 sheet was processed by ultrasonic shot peening treatment to fabricate a surface nanocrystalline,and a ball-on-disk dry sliding wear test was performed to evaluate the tribological behavior after treatment.The microstructure observation indicated a gradient nanocrystalline structure was formed after USSP treatment.The microhardness at the top surface was improved from 60 HV to 145 HV after treatment.The formed nanocrystalline resulted in an easy formation of MgO patches on the surface and reduced the coefficient of friction.Moreover,the formed nanocrystalline leaded to a retard of delamination with increasing the sliding speed and applied load,which was due to its stronger sub-surface.Under high sliding speed(0.5 m/s)and high applied load(50 N),it was firstly found that the formed nanocrystalline prevented the happening of thermal softening and melting.The possible reasons accounting for the prevention of thennal softening and melting were discussed accordingly.

关键词： AZ31Mg alloy Ultrasonic shot peening Surface-nanocrystallization Wear mechanism

A Review on Binderless Tungsten Carbide: Development and Application

在线全文

学校读者我要写书评

暂无评论

Nano-Micro Letters 2020年第1期12卷 158-194页

作者： Jialin Sun Jun Zhao Zhifu Huang Ke Yan Xuehui Shen jiandong Xing Yimin Gao yongxin jian Hejie Yang Bo Li State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi’an 710049People’s Republic of China Key Laboratory of High Efficiency and Clean Mechanical Manufacture of MOE School of Mechanical EngineeringShandong UniversityJinan 250061People’s Republic of China Key Laboratory of Education Ministry for Modern Design and Rotor‑Bearing System Xi’an Jiaotong UniversityXi’an 710049People’s Republic of China School of Mechanical and Automotive Engineering Qilu University of TechnologyJinan 250353People’s Republic of China

WC-Co alloys have enjoyed great practical significance owing to their excellent properties during the past decades.Despite the advantages,however,recently there have been concerns about the challenges associated with the use of Co,i.***.price instability,toxicity and properties degeneration,which necessitates the fabrication of binderless tungsten carbide(BTC).On the other hand,BTC or BTC composites,none of them,to date has been commercialized and produced on an industrial scale,but only used to a limited extent for specialized applications,such as mechanical seals undergoing high burthen as well as high temperature electrical contacts.There are two challenges in developing BTC:fully densifying the sintered body together with achieving a high toughness.Thus,this review applies towards comprehensively summarize the current knowledge of sintering behavior,microstructure,and mechanical properties of BTC,highlighting the densification improving strategies as well as toughening methods,so as to provide reference for those who would like to enhance the performance of BTC with better reliability advancing them to further wide applications and prepare the material in a way that is environment friendly,harmless to human health and low in production cost.This paper shows that the fabrication of highly dense and high-performance BTC is economically and technically feasible.The properties of BTC can be tailored by judiciously selecting the chemical composition coupled with taking into careful account the effects of processing techniques and parameters.

关键词： Binderless tungsten carbide Sintering Densification Toughening Mechanical properties

A robust and efficient algorithm for Chinese historical document analysis and recognition

在线全文

学校读者我要写书评

暂无评论

National Science Review 2023年第6期10卷 9-12页

作者： Chongyu Liu Cheng jian Jiarong Huang Wentao Yang yongxin Shi Qing jiang Lianwen Jin School of Electronic and Information Engineering South China University of Technology SCUT-Zhuhai Institute of Modern Industrial Innovation

PROBLEM Historical documents,which contain valuable information on historical knowledge and literary arts,are important mediums for the inheritance of human civilization.Therefore,the preservation of historical documents is considered to be an urgent research topic.One efficient way is to develop a document digitization system,which requires accurate historical document recognition and understanding.With the rapid development of optical character recognition techniques,historical document understanding has made great progress [1,2] and several benchmarkshave been established [3-5].

关键词：

基于局部放电的水轮发电机定子绕组层间间隙放电的检测与分析

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

绝缘材料 2024年第1期57卷 94-100页

作者：杨增杰赵显峰张学明李坚刘剑明孙永鑫华能澜沧江水电股份有限公司检修分公司云南昆明650000 华能澜沧江水电股份有限公司景洪水电厂云南景洪666100 哈动国家水力发电设备工程技术研究中心有限公司黑龙江哈尔滨150040

为提高绕组层间间隙放电故障诊断的可靠性,以水轮发电机定子绕组为试验对象,研究了通过局部放电诊断层间间隙放电时的影响因素。首先通过离线试验、在线试验、模拟试验方法获取绕组多放电源叠加时的层间间隙放电局放特征,然后通过线棒... 详细信息

为提高绕组层间间隙放电故障诊断的可靠性,以水轮发电机定子绕组为试验对象,研究了通过局部放电诊断层间间隙放电时的影响因素。首先通过离线试验、在线试验、模拟试验方法获取绕组多放电源叠加时的层间间隙放电局放特征,然后通过线棒模拟电气传导衰减,结合发电机绕组结构、检测距离,分析检测距离对检测结果的影响。结果表明:绕组层间的间隙放电有独立特征,在其PRPD模式图中脉冲分布呈悬浮状且具有对称的正负极性,脉冲峰值位于45°和225°前后,两相中一相的正负极性脉冲峰值同时向右偏离45°和225°,另一相的正负极性脉冲峰值同时向左偏离45°和225°;当绕组结构不同时,放电间隙分布和汇流环长度也不同,由此造成的检测距离差异对局部放电信号幅值检测结果有较大影响,如果只考虑电气传导,检测距离每增大1 m,局部放电幅值平均衰减约10%,当只有距离较近的一相能检测到间隙放电时相间分析方法失效;即使绕组中同时存在多个放电源和间隙放电也可以通过间隙放电PRPD模式图的悬浮特征识别层间间隙放电;检测量程对局部放电模式识别有影响,当大量程全局图谱完整但局部模式相互重叠时无法识别具体故障,当小量程全局图谱不完整但局部模式图清晰时可识别具体故障。

关键词：水轮发电机层间间隙放电 PRPD 传播衰减绕组结构悬浮特征

3D limit analysis of rock slopes based on equivalent linear failure criterion with tension cut-off

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2023年第12期15卷 3118-3130页

作者： Zhibin Sun Bowen Wang yongxin Li Jingshu Xu jian Ji School of Automotive and Transportation Engineering Hefei University of TechnologyHefei230009China Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai UniversityNanjing210024China College of Architecture and Civil Engineering Beijing University of TechnologyBeijing100124China

Hoek-Brown (HB) failure criterion is widely used to predict the strength of intact or heavily jointed rock mass. For stability analysis of rock slopes governed by the HB failure criterion, the equivalent linearity to Mohr-Coulomb (MC) criterion is often adopted, leading to the well-known equivalent Mohr-Coulomb method (EMCM). Existing studies on EMCM analysis mainly consider the shear strength of rock material, while consideration of the tensile strength is rare. This contradicts the fact that the underlying tensile strength of rock mass has considerable impact on the rock slope stability in real world. In this regard, this paper proposes a limit analysis-based approach that can account for tension in the three-dimensional (3D) stability analysis of HB rock slope. This approach is established on the equivalent linearity of the HB criterion with consideration of tensile strength, known as the equivalent tension cut-off MC method (ETMCM), and using a horn-like 3D mechanism of limit analysis. The safety factor solutions given by the proposed approach are validated by previous studies and numerical results. Parametric studies are conducted to investigate the effect of rock tensile strength on slope stability. Results show that the consideration of tension leads to a more conservative safety factor and a sharper curvature of the failure surface, and these impacts tend to be more obvious with the increases in slope inclination and slope width. Finally, the stability of the HB rock slope under seepage conditions is studied using the proposed approach. The results indicate that the effect of tensile strength is highly remarkable in seepage circumstances.

关键词： Rock slope Hoek-Brown criterion Stability analysis Tensile strength Limit analysis

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

电站锅炉受热面高温氯腐蚀特性及防控

洁净煤技术 2024年第6期30卷 7-15页

作者：马道洋李睿张兰坚永鑫王毅斌崔卫东谭厚章王学斌西安交通大学能源与动力工程学院陕西西安710049 河南省锅炉压力容器安全检测研究院河南郑州450016 西安交通大学材料科学与工程学院陕西西安710049

随着我国双碳战略目标提出,电站锅炉向高参数方向发展。为研究新疆典型高氯煤在高参数锅炉焚烧过程中可能存在的腐蚀问题,探索防护措施,模拟了高参数下燃用高氯煤的锅炉气氛,对比了Super 304、T92、C-HRA-5、TP347H和12Cr1MoV的抗氯腐... 详细信息

随着我国双碳战略目标提出,电站锅炉向高参数方向发展。为研究新疆典型高氯煤在高参数锅炉焚烧过程中可能存在的腐蚀问题,探索防护措施,模拟了高参数下燃用高氯煤的锅炉气氛,对比了Super 304、T92、C-HRA-5、TP347H和12Cr1MoV的抗氯腐蚀能力并研究腐蚀温度(600、650和700℃)对氯腐蚀特性的影响。同时探究不同氧化钇质量分数(0%、0.2%、0.4%、0.6%和0.8%)的In⁃conel 625涂层的抗氯腐蚀能力。结果表明:腐蚀温度对材料的抗氯腐蚀能力影响很大,当温度高于700℃时,Super 304、T92、C-HRA-5、TP347H和12Cr1MoV均无法满足实际投产使用。在650℃时,C-HRA-5和TP347H表现良好,其拟合的腐蚀增重曲线分别为:y^(2)=312.371x,R^(2)=0.96和y=1.927x,R^(2)=0.94。Inconel 625涂层明显提高了12Cr1MoV基体抗氯腐蚀能力。随着涂层中氧化钇含量增加,抗氯腐蚀效果呈先升高后降低趋势,添加0.4%氧化钇效果最好。

关键词：电站锅炉高氯煤氯腐蚀激光熔覆 Inconel625

维普期刊数据库博看期刊

Five new terpenoids from Viburnum odoratissimum var.sessiliflorum

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Natural Medicines 2023年第4期21卷 298-307页

作者： LI Yang jian Yajiao XU Fan LUO yongxin LI Zhixuan OU Yi WEN Yan JIN Jingwei ZHANG Chuarui GAN Lishe School of Biotechnology and Health Sciences International Healthcare Innovation InstituteWuyi UniversityJiangmen 529020China Chongqing Key Laboratory of Natural Product Synthesis and Drug Research School of Pharmaceutical SciencesChongqing UniversityChongqing 401331China Shandong Laboratory of Yantai Drug Discovery Bohai Rim Advanced Research Institute for Drug DiscoveryYantai 264117China College of Pharmaceutical Sciences Zhejiang UniversityHangzhou 310058China

Five new terpenoids,including two vibsane-type diterpenoids(1,2)and three iridoid allosides(3-5),together with eight known ones,were isolated from the leaves and twigs of Viburnum odoratissimum var.sessiliflorum.Their planar structures and relative configurations were determined by spectroscopic methods,especially 2D NMR techniques.The sugar moieties of the iridoids were confirmed asβ-D-allose by GC analysis after acid hydrolysis and acetylation.The absolute configurations of neovibsanin Q(1)and dehydrovibsanol B(2)were determined by quantum chemical calculation of their theoretical electronic circular dichroism(ECD)spectra and Rh2(OCOCF_(3))_(4)-induced ECD analysis.The anti-inflammatory activities of compounds 1,3,4,and 5 were evaluated using an LPS-induced RA W264.7 cell model.Compounds 3 suppressed the release of NO in a dose-dependent manner,with an IC_(50) value of 55.64μmol·L^(-1).The cytotoxicities of compounds 1-5 on HCT-116 cells were assessed and the results showed that compounds 2 and 3 exhibited moderate inhibitory activities with IC_(50) values of 13.8 and 12.3μmol·L^(-1),respectively.

关键词： Viburnum odoratissimum var.sessilifolrum Terpenoids Acid hydrolysis ECD calculation Anti-inflammation

Innovative preparation of Co@Cu Fe_(2)O_(4) composite via ball-milling assisted chemical precipitation and annealing for glorious electromagnetic wave absorption

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

International Journal of Minerals,Metallurgy and Materials 2023年第3期30卷 559-569页

作者： Xing Feng Pengfei Yin Limin Zhang Xiyuan Sun jian Wang Liang Zhao Changfang Lu Zhihua Gao yongxin Zhan College of Science Sichuan Agricultural UniversityYa’an 625014China School of Physical Science and Technology Northwestern Polytechnical UniversityXi’an 710072China

To deal with the growing electromagnetic hazards,herein a Co@CuFe_(2)O_(4)absorbing agent with excellent impedance matching at thin thickness was obtained via an innovative route of ball-milling assisted chemical precipitation and annealing.The as-prepared composite possesses excellent interface polarization ability due to sufficient contact between CuFe_(2)O_(4)NPs and flat Co,and this compressed Co lamella can also provide sufficient eddy current loss.Moreover,the dipole polarization,electron hopping/conduction,and structural scattering also contribute to the broadband microwave absorption of the composite.Thus,the minimum microwave reflection loss achieves-35.56 d B at12.93 GHz for 1.8 mm thickness,and the broadest efficient absorption bandwidth can reach 6.74 GHz for a thinner thickness of 1.72 mm.The preparation method reported here can be referenced as a new-type route to manufacture electromagnetic absorbers with outstanding performance.

关键词： electromagnetic wave absorption ball-milling cobalt copper ferrite

Microstructure and Mechanical Properties of Graphene Reinforced K418 Superalloy by Selective Laser Melting

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2022年第9期35卷 1477-1493页

作者： yongxin Lu Fan Luo Zhen Chen jian Cao Kai Song Lei Zhao Xueli Xu Hongduo Wang Wenya Li School of Material Science and Engineering Xi’an Shiyou UniversityXi’an710065China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin150001China School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an710072China State Key Laboratory of Manufacturing System Engineering Xi’an Jiaotong UniversityXi’an710049China School of Materials Science and Engineering Tianjin UniversityTianjin300350China Xi’an Key Laboratory of High Performance Oil and Gas Field Materials Xi’an Shiyou UniversityXi’an710065China

In order to obtain the superalloy with excellent properties, graphene reinforced K418 nickel base superalloy(GNPs/K418 composite) was prepared by selective laser melting technique in this study. Through systematically comparing and analyzing the microstructure and mechanical property of K418 superalloy and GNPs/K418 composite, it is found that the percentage of small-diameter grain(≤ 15 μm) increased from 84% to 90%, and the max strength of grain orientation() reduce from 5.76 to 4.17 due to the addition of GNPs. And GNPs can also improve the height and the full width at the half peak of the strong diffraction peak of GNPs/K418 composite. Besides, GNPs/K418 composite is a kind of sandwiched structure, which is consist of GNPs, carbides, and K418 matrix. Therefore, the hardness of the GNPs/K418 composite is 4.1% and 6.9% higher than that of the K418 matrix in the transverse and vertical direction, respectively. The room temperature tensile strength of the GNPs/K418 composite is 9% higher than that of the K418 matrix. And the 600℃ and 900℃ tensile strengths of the GNPs/K418 composite are 7.6% and 10.4% higher than that of the K418 matrix, respectively. It is inferred that the effect of graphene on K418 matrix strengthening is mainly fine grain strengthening and Orowan strengthening. However, the elongation rate of the composite material is reduced, which is attributed to crack sprouting at the interface between the matrix and GNPs under high stress.

关键词： Graphene K418 nickel base superalloy Selective laser melting Tensile properties