检索结果-南通市图书馆

Effect of Ti,Sc and Zr additions on microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-2Cu alloys

在线全文

学校读者我要写书评

暂无评论

China Foundry 2023年第2期20卷 125-133页

作者： Sai-heng Hou Jian Feng Song Chen Fan Zhang da-quan li State Key Laboratory of Nonferrous Metals and Processes GRINM Group Co.Ltd.Beijing 100088China GRIMAT Engineering Institute Co. Ltd.Beijing 101407China General Research Institute for Nonferrous Metals Beijing 100088China

The microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-2Cu alloys microalloyed with Ti,Sc and Sc+Zr were studied by optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction(XRD),hardness testing,and tensile *** swirled equilibrium enthalpy device(SEED)process was introduced to prepare the semisolid *** show that the addition of Ti,Sc,and Sc+Zr refines the grain size and improves the uniformity of the semisolid slurry and then suppresses the growth of theα-Al grain during solution heat *** microstructure of the four alloys in as-cast state mainly consists of sphericalα-Al and the Mg(Al,Cu,Zn)_(2)(η)eutectic ***,primary Al_(3)Sc,Al_(3)(Sc,Zr)and Al_(3)Zr are also found in the micro-alloying *** solution and aging heat treatment,most of the Mg(Al,Cu,Zn)_(2) phases dissolve into theα-Al matrix,while part of Mg(Al,Cu,Zn)_(2) phases transform to Al_(2)CuMg(S)***,the coarse primary Al_(3)Sc and Al_(3)(Sc,Zr)still remain in the matrix,and promote crack initiation and *** the tensile strength of 553 MPa,yield strength of 463 MPa and elongation of 13.4%at T6 state,trace Ti addition generates more attractive mechanical properties than the other three alloys.

关键词： Al-Zn-Mg-Cu alloys rheo-diecasting microstructure mechanical properties micro-alloying

Microstructure and mechanical property of MIM 418 superalloy

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2018年第1期37卷 35-39页

作者： Fu-Bao Yang Yan-Hong Jing dan li lin Zhang da-quan li Qiang Zhu National Engineering and Technology Research Center for Nonferrous Metal Matrix Composites General Research Institute for Nonferrous Metals Powder Metallurgy Research Institute University of Science and Technology Beijing

In this study, the influence of hot isostatic pressing（HIP） process on the 418 alloy produced by metal injection molding（MIM） technique（named as MIM 418）was investigated based on the characteristic analysis of 418 alloy powder. And comparison analysis of the microstructure and mechanical property between the MIM 418 and as-cast 418 alloys was performed by scanning electron microscopy（SEM）, energy-dispersive spectroscopy（EDS）,and X-ray diffraction（XRD）. The results show that MIM418 alloy exhibits fine grain（~30 μm） and uniform microstructure. The defects existing in MIM 418 alloy formed during sintering process can be eliminated through HIP treatment, and the relative density increases from97.0 % to 99.5 %. The mechanical property can be improved significantly because of the elimination of defects, and the tensile strength and elongation are1,271 MPa and 16.8 %, respectively, which are increased by 34.5 % and 180 % compared with K418 alloy after solution heat treatment.

关键词： K418 superalloy Metal injection molding Hot isostatic pressing Microstructure Mechanical property

Forming conditions of blisters during solution heat treatment of Al–Si alloy semi-solid die castings

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2023年第11期42卷 3851-3858页

作者： Hong-Xing Lu Qiang Zhu Stephen P.Midson Wen-Ying Qu Fan Zhang da-quan li National Engineering and Technology Research Center for Nonferrous Metal Matrix Composites General Research Institute for Nonferrous MetalsBeijing100088China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen518055China

In the present study,numerical simulation method was used to analyze the conditions,resulting in the formation of blisters during solution heat *** formation is considered to occur as the height of blister reaches 5μ*** effects of process parameters on the magnitude of the forming temperatures of blister(Tb)were *** kinds of Al-Si alloys were used to analyze the effect of mechanical properties of the alloys on blister forming *** results show that decreasing the initial pressure in gas hole,the long-short axial ratio of gas hole and the size of gas hole,as well as increasing the depth of gas hole and the strength of alloy are helpful to increase the critical temperature of forming *** conclusions are helpful for casters to understand the conditions controlling blister formation during solution heat treatment and take actions to avoid the blister defects.

关键词： Blister Forming condition Semi-solid die casting Aluminum alloy

Effects of Cu content on microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-xCu alloys

在线全文

学校读者我要写书评

暂无评论

China Foundry 2022年第4期19卷 321-326页

作者： Zhi-guang Ding Sai-heng Hou Song Chen Ze-hua liu da-quan li Jian Feng Fan Zhang li-ming Peng National Engineering Research Center of light Alloy Net Forming and Key State Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China General Research Institute for Nonferrous Metals Beijing 101407China

A systematic study on how Cu content affects the microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-xCu alloys during solution treatment and ageing heat treatment was *** swirled enthalpy equilibrium device(SEED)was adopted to prepare the semi-solid slurry of Al-6Zn-2Mg-xCu *** microstructure development and mechanical properties were studied using optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction(XRD),differential scanning calorimetry(DSC),as well as hardness and tensile *** grain boundary and shape factor were calculated using image processing software(Image-Pro Plus 6.0).Results show that the alloys are composed of typical globular primaryα-Al grains,eutectic phases,and smaller secondaryα-Al *** solution and ageing heat treatment,the eutectic phases are dissolved into Al matrix when the Cu content is lower than 1.5wt.%,while some eutectic phases transform into Al_(2)CuMg(S)phases and remain at grain boundaries when Cu content reaches 2wt.%.T6 heat treatment significantly enhances the mechanical properties of rheo-diecasting Al-6Zn-2Mg-xCu *** Cu concentration is 0.5wt.%-1.5wt.%,the ultimate tensile strength,yield strength and elongation of T6 treated alloys rise to around 500 MPa,420 MPa,and 18%,respectively.

关键词： Al-Zn-Mg-Cu alloy rheo-diecasting Cu content mechanical properties heat treatment

The Fuzzy Cluster Analysis in Identification of Key Temperatures in Machine Tool

在线全文

学校读者我要写书评

暂无评论

厦门大学学报（自然科学版） 2002年第S1期41卷 88-89页

作者： ZHAO da-quan 1, ZHENG li 1, XIANG Wei-hong 1, li Kang 1, liU da-cheng 1, ZHANG Bo-peng 2 (1. Department of Industrial Engineering, Tsinghua University, 2. Department of Precision Instruments and Mechanology, Tsinghua University, B eijing 100084, China)

The thermal-induced error is a very important sour ce of machining errors of machine tools. To compensate the thermal-induced machin ing errors, a relationship model between the thermal field and deformations was needed. The relationship can be deduced by virtual of FEM (Finite Element Method ), ANN (Artificial Neural Network) or MRA (Multiple Regression Analysis). MR A is on the basis of a total understanding of the temperature distribution of th e machine tool. Although the more the temperatures measured are, the more accura te the MRA is, too more temperatures will hinder the analysis calculation. So it is necessary to identify the key temperatures of the machine tool. The selectio n of key temperatures decides the efficiency and precision of MRA. Because of th e complexities and multi-input and multi-output structure of the relationships , the exact quantitative portions as well as the unclear portions must be taken into consideration together to improve the identification of key temperatures. I n this paper, a fuzzy cluster analysis was used to select the key temperatures. The substance of identifying the key temperatures is to group all temperatures b y their relativity, and then to select a temperature from each group as the repr esentation. A fuzzy cluster analysis can uncover the relationships between t he thermal field and deformations more truly and thoroughly. A fuzzy cluster ana lysis is the cluster analysis based on fuzzy sets. Given U={u i|i=0,...,N}, in which u i is the temperature measured, a fuzzy matrix R can be obta ined. The transfer close package t(R) can be deduced from R. A fuzzy clu ster of U then conducts on the basis of t(R). Based on the fuzzy cluster analysis discussed above, this paper identified the k ey temperatures of a horizontal machining center. The number of the temperatures measured was reduced to 4 from 32, and then the multiple regression relationshi p models between the 4 temperatures and the thermal deformations of the spind

关键词： The Fuzzy Cluster Analysis in Identification of Key Temperatures in Machine Tool

Semi-solid processing of aluminum and magnesium alloys:Status,opportunity,and challenge in China

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2021年第11期31卷 3255-3280页

作者： Gan li Wen-ying QU Min LUO Le CHENG Chuan GUO Xing-gang li Zhen XU Xiao-gang HU da-quan li Hong-xing LU Qiang ZHU Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China Academy for Advanced Interdisciplinary Studies Southern University of Science and TechnologyShenzhen 518055China GRIMAT Engineering Institute Co. Ltd.Beijing 101407China

Owing to its low cost,short process and low energy consumption,semi-solid processing(SSP)of aluminum(Al)and magnesium(Mg)alloys has been considered as a competitive approach to fabricate complicated components with excellent *** the past decade,significant progress has been achieved in deeply understanding the SSP process,the microstructure and performance of the fabricated components in *** paper starts with a retrospective overview of some common slurry preparation methods,followed by presenting the performance and the underlying mechanisms of SSP fabricated ***,the mainstream opinions on the microstructure evolution and rheological flow behavior of semi-solid slurry are ***,the general situation and some recent examples of industrial applications of SSP are ***,special attention is paid to the unresolved issues and the future directions in SSP of Al and Mg alloys in China.

关键词： semi-solid processing aluminum alloys magnesium alloys slurry preparation numerical modeling performance industrial applications

Utilizing engineered extracellular vesicles as delivery vectors in the management of ischemic stroke:a special outlook on mitochondrial delivery

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2025年第8期20卷 2181-2198页

作者： Jiali Chen Yiyang li Xingping quan Jinfen Chen Yan Han li Yang Manfei Zhou Greta Seng Peng Mok Ruibing Wang Yonghua Zhao Institute of Chinese Medical Sciences State Key Laboratory of Quality Research in Chinese MedicineUniversity of MacaoTaipaMacao Special Administrative RegionChina Department of Pharmacy Hunan Provincial People’s Hospitalthe First Affiliated Hospital of Hunan Normal UniversityChangshaHunan ProvinceChina Department of Electrical and Computer Engineering University of MacaoTaipaMacao Special Administrative RegionChina Department of Pharmaceutical Sciences Faculty of Health SciencesUniversity of MacaoTaipaMacao Special Administrative RegionChina

Ischemic stroke is a secondary cause of mortality worldwide,imposing considerable medical and economic burdens on *** vesicles,serving as natural nanocarriers for drug delivery,exhibit excellent biocompatibility in vivo and have significant advantages in the management of ischemic ***,the uncertain distribution and rapid clearance of extracellular vesicles impede their delivery *** utilizing membrane decoration or by encapsulating therapeutic cargo within extracellular vesicles,their delivery efficacy may be greatly ***,previous studies have indicated that microvesicles,a subset of large-sized extracellular vesicles,can transport mitochondria to neighboring cells,thereby aiding in the restoration of mitochondrial function post-ischemic *** extracellular vesicles have also demonstrated the capability to transfer mitochondrial components,such as proteins or deoxyribonucleic acid,or their sub-components,for extracellular vesicle-based ischemic stroke *** this review,we undertake a comparative analysis of the isolation techniques employed for extracellular vesicles and present an overview of the current dominant extracellular vesicle modification *** the complex facets of treating ischemic stroke,we also delineate various extracellular vesicle modification approaches which are suited to different facets of the treatment ***,given the burgeoning interest in mitochondrial delivery,we delved into the feasibility and existing research findings on the transportation of mitochondrial fractions or intact mitochondria through small extracellular vesicles and microvesicles to offer a fresh perspective on ischemic stroke therapy.

关键词： delivery engineering extracellular vesicles identification ischemic stroke isolation mitochondria targeting strategy therapeutic effects

木犀草素调控Nrf2/HO-1通路保护视网膜色素上皮细胞氧化损伤

在线全文

学校读者我要写书评

暂无评论

国际眼科杂志 2021年第1期21卷 21-26页

作者：洪萌洪道先石荣先魏聪赵晓丽李权达河南大学第一附属医院眼科中国河南省开封市475001 河南大学第一附属医院麻醉科中国河南省开封市475001

目的:探讨木犀草素对H2O2诱导的视网膜色素上皮(RPE)细胞氧化损伤的保护作用及其机制。方法:将ARPE-19细胞分为对照组、H2O2组、不同剂量木犀草素组和Nrf2抑制剂组,除对照组外均采用100μmol/L H2O2制备RPE氧化损伤模型。采用四甲基偶... 详细信息

目的:探讨木犀草素对H2O2诱导的视网膜色素上皮(RPE)细胞氧化损伤的保护作用及其机制。方法:将ARPE-19细胞分为对照组、H2O2组、不同剂量木犀草素组和Nrf2抑制剂组,除对照组外均采用100μmol/L H2O2制备RPE氧化损伤模型。采用四甲基偶氮唑盐(MTT)法检测细胞活力并确定木犀草素处理浓度,采用流式细胞仪检测细胞凋亡率及活性氧(ROS)含量,采用试剂盒法检测细胞中丙二醛(Mda)和超氧化物歧化酶(SOD)含量,采用Western blot检测细胞Caspase-3、多聚腺苷酸二磷酸核糖聚合酶(PARP)、B细胞淋巴瘤-2(Bcl-2)、核因子E2相关因子2(Nrf2)及血红素氧化酶-1(HO-1)蛋白表达水平。结果:100μmol/L木犀草素对ARPE-19具有毒性作用,因此选择25μmol/L和50μmol/L木犀草素进行后续实验。与H2O2组比较,25μmol/L和50μmol/L木犀草素组细胞活力明显升高,凋亡率降低,ROS和Mda含量明显减少,SOD活性明显升高,Caspase-3和PARP蛋白表达水平明显降低,Bcl-2、Nrf2及HO-1蛋白表达水平明显升高(Pda含量明显升高[(654.96±26.99)vs(446.52±29.42),(3.89±0.29)nmol/mL vs(2.06±0.19)nmol/mL],SOD活性明显降低[(13.83±1.49)U/mL vs(22.69±1.83)U/mL],Caspase-3和PARP蛋白表达水平明显升高,Bcl-2、Nrf2及HO-1蛋白表达水平明显降低(P<0.05)。结论:木犀草素能够改善H2O2诱导的RPE细胞氧化损伤,其作用机制与激活Nrf2/HO-1通路有关。

关键词：木犀草素视网膜色素上皮细胞氧化损伤核因子E2相关因子2 血红素氧化酶-1

MXene Hybridized Polymer with Enhanced Electromagnetic Energy Harvest for Sensitized Microwave Actuation and Self-Powered Motion Sensing

在线全文

学校读者我要写书评

暂无评论

NANO-MICRO LETTERS 2025年第1期17卷 1-15页

作者： Wang, Yu-Ze Wang, Yu-Chang liu, Ting-Ting Zhao, quan-liang li, Chen-Sha Cao, Mao-Sheng Beijing Inst Technol Sch Mat Sci & Engn Beijing 100081 Peoples R China Peking Univ Sch Mat Sci & Engn Beijing 100871 Peoples R China North China Univ Technol Sch Mech & Mat Engn Beijing 100144 Peoples R China Heilongjiang Univ Minist Educ Peoples Republ China Key Lab Funct Inorgan Mat Chem Harbin 150080 Peoples R China

Polymeric microwave actuators combining tissue-like softness with programmable microwave-responsive deformation hold great promise for mobile intelligent devices and bionic soft robots. However, their application is challenged by restricted electromagnetic sensitivity and intricate sensing coupling. In this study, a sensitized polymeric microwave actuator is fabricated by hybridizing a liquid crystal polymer with Ti3C2Tx (MXene). Compared to the initial counterpart, the hybrid polymer exhibits unique space-charge polarization and interfacial polarization, resulting in significant improvements of 230% in the dielectric loss factor and 830% in the apparent efficiency of electromagnetic energy harvest. The sensitized microwave actuation demonstrates as the shortened response time of nearly 10 s, which is merely 13% of that for the initial shape memory polymer. Moreover, the ultra-low content of MXene (up to 0.15 wt%) benefits for maintaining the actuation potential of the hybrid polymer. An innovative self-powered sensing prototype that combines driving and piezoelectric polymers is developed, which generates real-time electric potential feedback (open-circuit potential of similar to 3 mV) during actuation. The polarization-dominant energy conversion mechanism observed in the MXene-polymer hybrid structure furnishes a new approach for developing efficient electromagnetic dissipative structures and shows potential for advancing polymeric electromagnetic intelligent devices.

关键词： Microwave absorption Electromagnetic response Energy harvest Self-sensing Soft actuator