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  • Memantine-Loaded PEGylated Biodegradable Nanoparticles for the Treatment of Glaucoma
    Small (IF 8.643) Pub Date : 2017-11-20
    Elena Sánchez-López, Maria Antonia Egea, Benjamin Michael Davis, Li Guo, Marta Espina, Amelia Maria Silva, Ana Cristina Calpena, Eliana Maria Barbosa Souto, Nivedita Ravindran, Miren Ettcheto, Antonio Camins, Maria Luisa García, Maria Francesca Cordeiro
    更新日期:2017-11-20
  • High-Performance Aqueous Zinc–Ion Battery Based on Layered H2V3O8 Nanowire Cathode
    Small (IF 8.643) Pub Date : 2017-11-20
    Pan He, Yueli Quan, Xu Xu, Mengyu Yan, Wei Yang, Qinyou An, Liang He, Liqiang Mai
    更新日期:2017-11-20
  • Recent Advances in Nonfullerene Acceptors for Organic Solar Cells
    Macromol. Rapid Commun. (IF 4.265) Pub Date : 2017-11-20
    Fuchuan Liu, Tianyu Hou, Xiangfei Xu, Liya Sun, Jiawang Zhou, Xingang Zhao, Shiming Zhang
    更新日期:2017-11-20
  • Self-Assembled 3D Helical Hollow Superstructures with Enhanced Microwave Absorption Properties
    Macromol. Rapid Commun. (IF 4.265) Pub Date : 2017-11-20
    Yang Yang, Jianqi Zhang, Wenjun Zou, Sai Wu, Fan Wu, Aming Xie, Zhixiang Wei
    更新日期:2017-11-20
  • Exclusive Synthesis of Poly(3-hexylthiophene) with an Ethynyl Group at Only One End for Effective Block Copolymerization
    Macromol. Rapid Commun. (IF 4.265) Pub Date : 2017-11-20
    Geng Zhang, Yoshihiro Ohta, Tsutomu Yokozawa
    更新日期:2017-11-20
  • Multiscale design of high-voltage multilayer energy-storage ceramic capacitors
    J. Am. Ceram. Soc. (IF 2.841) Pub Date : 2017-11-20
    Ziming Cai, Xiaohui Wang, Bingcheng Luo, Wei Hong, Longwen Wu, Longtu Li

    Multilayer energy-storage ceramic capacitors (MLESCCs) are studied by multiscale simulation methods. Electric field distribution of a selected area in a MLESCC is simulated at a macroscopic scale to analyze the effect of margin length on the breakdown strength of MLESCC using a finite element method. Phase field model is introduced to analyze the dielectric breakdown mechanism of MLESCC at a mesoscopic scale. The microstructure of selected area is generated through voronoi tessellation random construction routine containing core-shell-structured dielectric materials. The effects of margin length, shell permittivity, and shell volume fraction on the breakdown strength of MLESCC are respectively studied. Results indicate that the breakdown strength of MLESCC can be enhanced by adopting larger margin lengths, or by increasing the shell permittivity or volume fraction.

    更新日期:2017-11-20
  • Effect of topological structure on photoluminescence of PbSe quantum dot-doped borosilicate glasses
    J. Am. Ceram. Soc. (IF 2.841) Pub Date : 2017-11-20
    Zhousu Xu, Xiaofeng Liu, Chun Jiang, Dewei Ma, Jinjun Ren, Cheng Cheng, Jianrong Qiu

    Borosilicate glasses doped with PbSe quantum dots (QDs) were prepared by a conventional melt-quenching process followed by heat treatment, which exhibit good thermal, chemical, and mechanical stabilities, and are amenable to fiber-drawing. A broad near infrared (NIR) photoluminescence (PL) emission (1070-1330 nm) band with large full-width at half-maximum (FWHM) values (189-266 nm) and notable Stokes shift (100-210 nm) was observed, which depended on the B2O3 concentration. The PL lifetime was about 1.42-2.44 μs, and it showed a clear decrease with increasing the QDs size. The planar [BO3] triangle units forming the two-dimensional (2D) glass network structure clearly increased with increasing B2O3 concentration, which could accelerate the movement of Pb2+ and Se2− ions and facilitate the growth of PbSe QDs. The tunable broadband NIR PL emission of the PbSe QD-doped borosilicate glass may find potential application in ultra-wideband fiber amplifiers.

    更新日期:2017-11-20
  • Highly porous Y2SiO5 ceramic with extremely low thermal conductivity prepared by foam-gelcasting-freeze drying method
    J. Am. Ceram. Soc. (IF 2.841) Pub Date : 2017-11-20
    Zhen Wu, Luchao Sun, Jingjing Pan, Jingyang Wang

    Foam-gelcasting-freeze drying method is developed to fabricate porous Y2SiO5 ceramic with ultrahigh porosity of 92.2%-95.8% and isotropous multiple pore structures. As prepared porous samples have quite low shrinkages of 0.8%-1.9% during demolding and drying processes, lightweights of 0.19-0.35 g/cm3, and extremely low thermal conductivities of 0.054-0.089 W·(m·K)−1. Our approach combines the merits of foam-gelcasting method and freeze drying method. It is a simple and effective method to fabricate porous ceramics with very high porosity and extremely low thermal conductivity through low shrinkage of green body and near net complex shape forming.

    更新日期:2017-11-20
  • Highly porous mullite ceramics from engineered alkali activated suspensions
    J. Am. Ceram. Soc. (IF 2.841) Pub Date : 2017-11-20
    Acacio Rincón Romero, Hamada Elsayed, Enrico Bernardo

    Air may be easily incorporated by vigorous mechanical stirring, with the help of surfactants, of activated geopolymer-yielding suspensions. The cellular structure is stabilized by the viscosity increase caused by curing reactions, configuring an “inorganic gel casting”. The present paper is aimed at extending this approach to mullite foams, obtained by the thermal treatment of engineered alkali activated suspensions. “Green” foams were first obtained by gel casting of a suspension for Na-geopolymer enriched with reactive γ-Al2O3 powders. Sodium was later extracted by ionic exchange with ammonium salts. In particular, the removal of Na+ ions was achieved by immersion in ammonium nitrate solution overnight, with retention of the cellular structure. Finally, the ion-exchanged foams were successfully converted into pure mullite foams by application of a firing treatment at 1300°C, for 1 hour. Preliminary results concerning the extension of the concept to mullite three-dimensional scaffolds are presented as well.

    更新日期:2017-11-20
  • Valence state and ionic conduction in Mn-doped MgO partially stabilized zirconia
    J. Am. Ceram. Soc. (IF 2.841) Pub Date : 2017-11-20
    Buyoung Kim, Heesoo Lee

    The mechanism of the enhancement in the ionic conductivity resulting from cubic phase stabilization in MgO partially stabilized zirconia (MgPSZ) by Mn doping was studied by examining the local Zr-O structure. Cubic phase (14 vol%) in MgPSZ was increased with the addition of MnO2, and 10 mol% Mn-doped MgPSZ exhibited the highest cubic phase fraction (98.72%), which was analyzed by Rietveld refinement. In addition, only the cubic phase, not the monoclinic and tetragonal phases, was observed in the TEM-SAED pattern of 10 mol% Mn-doped MgPSZ. Doped Mn exhibited a high Mn2+/Mn4+ ratio, which was identified by X-ray photoelectron spectroscopy (XPS). In addition, it indicates that oxygen vacancy formation by substitution of Mn2+ in the Zr4+ site in MgPSZ increased cubic phase fraction. Ionic conductivity of MgPSZ was improved by the cubic phase increase attributed to Mn doping, and 10 mol% Mn-doped MgPSZ exhibited higher ionic conductivity than MgPSZ. To investigate the mechanism of the ionic conductivity improvement, Zr-O local structure in Mn-doped MgPSZ was analyzed by Zr K-edge EXAFS of MgPSZ, and the number of bonding of the Zr-O first shell decreased with increased Mn substitution. Therefore, it was considered that the oxygen vacancy generation led to an increase in the cubic phase and the number of ionic conduction sites.

    更新日期:2017-11-20
  • Radio-frequency negative permittivity in the graphene/silicon nitride composites prepared by spark plasma sintering
    J. Am. Ceram. Soc. (IF 2.841) Pub Date : 2017-11-20
    Chuanbing Cheng, Runhua Fan, Zhongyang Wang, Peitao Xie, Chuanxin Hou, Guohua Fan, Yanhua Lei, Liqiong An, Yao Liu

    Graphene/silicon nitride (GR/Si3N4) ceramic composites with uniformly dispersed GR sheets were prepared using spark plasma sintering. The effects of GR content on the microstructure and electrical properties of the composites were investigated in detail. With the GR content rising, the conductive GR network was formed in the composites, leading to the appearance of a percolation phenomenon, and the conductive mechanism also changed from hopping conductivity to metal-like conductivity. When the GR content reached the percolation threshold, the composites showed a negative permittivity behavior, which resulted from the low frequency plasmonic state generated by the formative conducting GR networks. The increasing GR content resulted in a higher plasma frequency and larger magnitude of negative permittivity, which was consistent with the analysis of Drude model. A relatively high dielectric loss was observed in the composites and mainly induced by the high leakage current among GR sheets. Our work is beneficial to expound the regulation mechanism of negative permittivity, and the obtained ceramic composites present some potential applications in microwave absorption, shielding and capacitors.

    更新日期:2017-11-20
  • Thermal properties and phase stability of Yttria-Stabilized Zirconia (YSZ) coating deposited by Air Plasma Spray onto a Ni-base Superalloy
    Ceram. Int. (IF 2.986) Pub Date : 2017-11-20
    D.F. Zambrano, A. Barrios, L. Tobón, C. Serna, P. Gómez, J.D. Osorio, A. Toro

    Thermal properties and microstructure characterization of Yttria Stabilized Zirconia (YSZ) Thermal Barrier Coatings (TBCs) deposited by Air Plasma Spray (APS) onto a Ni-base superalloy (Inconel 625) were studied. Two separate sets of tests were performed. The first one consisted in Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) performed over free-standing TC samples detached from TBCs. The second one included the analysis of the cross section of samples heat treated at 1100 °C with holding times of 600, 1000, and 1700 h. The TC porosity was analyzed for different heat treatment conditions so that inter-lamellar, intra-lamellar and globular pores, as well as cracks, were identified and quantified independently. An initial porosity reduction related to inter-lamellar and intra-lamellar pores, as well as cracks, was observed during the first 600 hours of heat treatment, due to sintering. However, porosity continually increased during heat treatment from 600 to 1700 h driven by volumetric changes associated to phase transformations. During this period, yttrium diffused from the metastable tetragonal phase favoring the transformation to cubic phase while monoclinic phase transformed after cooling from the yttrium-depleted tetragonal phase. Energy absorption curves and the variation of heat capacity with temperature were also determined and correlated to microstructural changes.

    更新日期:2017-11-20
  • The sintering behavior of plasma-sprayed YSZ coating over the delamination crack in low temperature environment
    Ceram. Int. (IF 2.986) Pub Date : 2017-11-20
    Hui Dong, Jian-Tao Yao, Xiao Li, Yong Zhou, Yuan-Bo Li

    The sintering behavior of plasma-sprayed yittra-stablized zirconia (YSZ) coating over the delamination crack and its influence on YSZ cracking were investigated via gradient thermal cycling test and finite element model (FEM). The gradient thermal cycling test was performed at a peak surface temperature of 1150 °C with a duration of 240 s for each cycle. A three-dimensional model including delamination cracks with different lengths was employed to elaborate the temperature evolution characteristics in YSZ coating over the delamination cracks. The temperature over the delamination crack increases linearly with the crack propagation, which continuously promotes the sintering of YSZ coating in the region. As a result, the YSZ coating over the delamination crack sinters dramatically despite of the low temperature exposure. Meanwhile, the temperature distribution difference in YSZ coating induces an nonuniform sintering along both free surface and thickness of YSZ coating. Correspondingly, the maximum vertical crack driving force locates at the YSZ free surface over the delamination crack center, which makes the vertical cracks generate in this region and propagate to the interface of YSZ /bond coat with YSZ further sintering. The vertical crack promotes the delamination crack propagation via accelerating the oxidation velocity of the bond coat. The influence of temperature rise on delamination crack propagation can be divided into two stages: the little contribution stage and the promotion stage. For the actual engine exposure to low temperature, the study of phase transformation of YSZ over the delamination crack is indeed needed because of an extended remarkable temperature rise period.

    更新日期:2017-11-20
  • Hydrothermal synthesis of TiO2 nanotubes from one-dimensional TiO2 nanowires on flexible non-metallic substrate
    Ceram. Int. (IF 2.986) Pub Date : 2017-11-20
    Yin-Yu Sun, Zhi-Min Zong, Zhan-Ku Li, Xian-Yong Wei

    TiO2 nanotubes (NTs) immobilized on carbon fibers (CFs) were successfully prepared by a hydrothermal synthesis method based on alkali treatment of TiO2 nanowires (NWs). The as-prepared CFs with TiO2-NTs (CFs/TiO2-NTs) were characterized with a field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), energy dispersive spectrometer (EDS), X-ray photoelectron spectrometer (XPS), and X-ray diffractometer (XRD). The images on FESEM and TEM show that the entire surfaces of CFs are covered by TiO2-NTs with the thickness of ca. 7.4 μm. The inner and outer diameters of TiO2-NTs are ca. 4.6 and 8.7 nm, respectively. The analyses with EDS and XPS indicate that the main elements on the surface of CFs/TiO2-NTs are C, O, and Ti. According to the analysis with XRD, the transformation from titanate NTs to anatase TiO2-NTs was realized after annealing treatment. This work may provide a novel method for immobilizing TiO2-NTs on flexible non-metallic substrates.

    更新日期:2017-11-20
  • Discrete element simulation of SiC ceramic containing a single pre-existing flaw under uniaxial compression
    Ceram. Int. (IF 2.986) Pub Date : 2017-11-17
    Shengqiang Jiang, Xu Li, Li Zhang, Yuanqiang Tan, Ruitao Peng, Rui Chen

    A model of a SiC ceramic containing a single pre-existing flaw was established based on the discrete element method. The effects of the flaw inclination angles, which ranged from 0° to 75°, on the mechanical properties of the specimen under uniaxial compression were studied. The evolution of the force-chain field, displacement field and stress field around the pre-existing flaw in the process from the load to failure was also analysed. The results showed that the flaw inclination angle affected the mechanical properties of the specimen as well as the initiation and propagation of the first crack. Based on the investigation of the force chain field, it was found that the distribution curve of the normal force carried by the parallel bond in the specimen with the corresponding angles under compression is similar to the “peanut” rose diagram, while the shear force distribution curve is similar to the "butterfly wings" rose diagram. In addition, in the analysis of the displacement field and the stress field, the displacement field around the flaw can be divided into four types in the process from specimen loading to its failure. Meanwhile, it was found that initiation of the first crack was affected by tensile stress. With the propagation of the first crack, the tensile stress concentration region at the flaw tip moved and dissipated correspondingly.

    更新日期:2017-11-20
  • Effect of biaxial cold pressure densification (BCPD) on Ba0.6K0.4Fe2As2 round wire using optimized precursor
    Ceram. Int. (IF 2.986) Pub Date : 2017-11-17
    X. Li, E.W. Collings, F. Wan, M.D. Sumption, S.C. Xue, D.L. Zhang, M.A. Rindfleisch, M.J. Tomsic, Z.X. Shi

    (Ba,Sr)1-xKxFe2As2 superconductor is of great interest as a wire for practical applications. In this paper, Ba0.6K0.4Fe2As2 precursor powder was prepared by high-energy ball-milling aided sintering (12 h/750 °C). The prepared precursor was drawn to powder-in-tube round wire. Partial as-drawn wires were subjected to biaxial cold pressure densification (BCPD) at 0.5 and 1.0 GPa, followed by an annealing for 1 min/770 °C. According to our results, the BCPD improved the grain connectivity of the BCPDed wires without degrading the superconductivity. A (Ba,Sr)1-xKxFe2As2 round-wire record transport critical current density, 1.14×105 A/cm2 (4.2 K, 2 T), was observed in our BCPDed samples.

    更新日期:2017-11-20
  • Cu doped LiNi0.5Mn1.5-xCuxO4 (x=0, 0.03, 0.05, 0.10, 0.15) with significant improved electrochemical performance prepared by a modified low temperature solution combustion synthesis method
    Ceram. Int. (IF 2.986) Pub Date : 2017-11-17
    H.Y. Sun, X. Kong, B.S. Wang, T.B. Luo, G.Y. Liu

    A series of Cu-doped LiNi0.5Mn1.5-xCuxO4 (x=0, 0.03, 0.05, 0.10, 0.15) spinel samples have been successfully prepared using a modified low temperature solution combustion synthesis method. X-ray diffraction(XRD) and infrared spectroscopy(FT-IR) analysis are used to characterize the phase structure. Scanning electron microscopy(SEM) is used to observe the microstructure of the products. The electrochemical performance are studied by galvanostatic charge-discharge testing, cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). No obvious sencondary phases were observed in XRD patterns of as-synthesized LiNi0.5Mn1.5-xCuxO4 powders. The samples have a combination structure of ordered and disordered space group and the order degree increases with the increase of Cu doping content obtained from FT-IR spectra. The electrochemical performances show that although the specific capacity decreases with the Cu-doping content, the cycle-life both at room temperature and 55°C and the C-rate performance are remarkably improved. The factors of stable structure, grain refinement, better crystallinity and lower charge transfer resistance lead to the excellent performance of Cu-doped samples.

    更新日期:2017-11-20
  • Microstructure, phase compositions and in vitro evaluation of freeze casting hydroxyapatite-silica scaffolds
    Ceram. Int. (IF 2.986) Pub Date : 2017-11-17
    Zheng-Quan Jia, Zuo-Xing Guo, Fei Chen, Jing-Juan Li, Lei Zhao, Li Zhang

    Hydroxyapatite-silica (HA-SiO2) scaffolds with different SiO2 content (0, 2, 5 and 10 wt.% SiO2) were fabricated by freeze casting. After sintering, the scaffolds maintained the interconnected unidirectional pore channels by removing the frozen ice crystals via sublimation. X-ray diffraction (XRD) analysis indicated that SiO2 promoted the decomposition of HA to tricalcium phosphate (TCP), comprised of α-TCP and β-TCP, which became more apparent with the increase of SiO2 content. The microstructure observation of scanning electron microscope (SEM) showed that the scaffolds surface feature had great changes in terms of grain size and grain boundary with the addition of SiO2. Moreover, the addition of SiO2 could increase the porosity and pore size of the scaffolds, even allowing it to reach a maximum as the SiO2 content increased to 5 wt.%. Compression tests investigated the variation in the compressive strength of the scaffolds with the increase in the SiO2 content, which showed first decreasing and then increasing behavior. In vitro evaluation results in simulated body fluid (1.5×SBF) revealed that the introduction of SiO2 enhanced the growth rate of bone-like layer, especially the scaffold with 5 wt.% SiO2, which exhibited faster growth rate of bone-like layer than the other scaffolds. The XRD and fourier transformed infrared spectroscopy (FT-IR) characterization confirmed that the bone-like layer formed on the scaffold surface was a carbonate-containing hydroxyapatite bone-like layer.

    更新日期:2017-11-20
  • Preparation, Characterization of 1D ZnO nanorods and their gas sensing Properties
    Ceram. Int. (IF 2.986) Pub Date : 2017-11-17
    Supriya B. Jagadale, Vithoba L. Patil, Sharadrao A. Vanalakar, Pramod S. Patil, Harish P. Deshmukh

    The 1D ZnO nanorods (NR's) were grown with Zinc (Zn) ion precursor concentration variation on seed layer glass substrate by the low temperature hydrothermal method and utilized for nitrogen dioxide (NO2) gas sensing application. Zn ion precursor concentration varied as 0.02, 0.03, 0.04, 0.05 and 0.06 M and thin films were characterized for structural, morphological, optical, electrical, surface defect study and gas sensing properties. All the film showed dominant orientation along the (002) direction, the intensity of the peak vary with the length of the nanorods. SEM cross images confirmed that nanorods had vertical alignment perpendicular to the plane of the substrate surface. The PL intensity of oxygen vacancy related defects for prepared samples was found to be linearly proportional to gas sensing phenomena. This result in good agreement with the theoretical postulation that, oxygen vacancies plays the important role for adsorption sites to NO2 molecule. The gas sensing performance was studied as a function of operating temperature, Zn ion precursor concentration variation, and gas concentration. The maximum gas response is 113.32 to 100ppm NO2 gas at 150 °C for 0.05 M sample out of all prepared samples. Additionally, ZnO thin film sensor has potential to detect NO2 as low as 5 ppm.

    更新日期:2017-11-20
  • Reduced graphene oxide film with record-high conductivity and mobility
    Mater. Today (IF 21.695) Pub Date : 2017-11-20
    Yilin Wang, Yanan Chen, Steven D. Lacey, Lisha Xu, Hua Xie, Tian Li, Valencia A. Danner, Liangbing Hu

    Graphene has attracted significant attention in both scientific and industrial fields. The scalable and high-yield chemical functionalization methods have been widely used to produce graphene, such as reduced graphene oxide (RGO). However, previously reported conductivity (<1500 S cm−1) and mobility (<5 cm2 V−1 s−1) values for RGO film are relatively low, which limits its application in many fields. In this work, we report a RGO film with a record-high conductivity of 6300 S cm−1 and a record-high mobility of 320 cm2 V−1 s−1, which was reduced by Joule heating at an extremely high temperature of 3000 K. Thermal reduction process challenges of Joule heating were overcome by employing a two-step reduction and a curved RGO film. An investigation into how charge transport properties of RGO film are influenced by the reduction temperature was pursued. As the reduction temperature increases, the oxygen-containing functional groups, acting as dopant sources and scattering centers, are gradually removed, such that the carrier density gradually decreases, and the mobility and conductivity gradually increases. The localization length, corresponding to the size of graphitic sp2 domains, is 8.7 nm for the 3000-K-reduced RGO film, which exceeds previously reported values. The unique features of the reported 3000-K-reduced RGO film, such as less defects/impurities and large graphitic sp2 domains within a dense structure, enable both record-high conductivity and mobility.

    更新日期:2017-11-20
  • Metallic glass nanotube arrays: Preparation and surface characterizations
    Mater. Today (IF 21.695) Pub Date : 2017-11-20
    Jem-Kun Chen, Wei-Ting Chen, Chih-Chia Cheng, Chia-Chi Yu, Jinn P. Chu

    In this study, we fabricated first-ever metallic glass nanotubes (MGNTs) in a distinct pattern on a Si substrate, by sputter-depositing a coating of metallic glass (Zr55Cu30Al10Ni5) over a contact-hole array template created in photoresist. The resulting nanotubes were 500 or 750 nm in height with a diameter of 500 or 750 nm and wall thickness ranging from 44 nm to 103 nm. The structure of the nanotubes was preserved by the high strength and ductility of the metallic glass during the removal of the photoresist template under ultrasonic vibration. We observed an increase in the hydrophobicity of the MGNT with an increase in the thickness of the walls, with the thickest walls presenting an apparent contact angle of 139°. The hydrophobicity is due to air trapped within the tubes, which prevents the intrusion of water into the nanostructures. We also observed thermal-response behavior on the surface of the MGNT array. Surface cooling produced negative pressure within the nanochambers, which created a sucking force against the water droplets. Surface heating produced positive pressure within the nanochambers, which actually lifted the droplets. This thermal-response behavior was shown to be reversible for at least five cycles between 25 and 55 °C. The MGNT created adhesion forces reaching 14.2 N cm−2, which was sufficient to secure the water droplets even when the surface was tilted or completely inverted. The MGNT array in this study represents a biomimetic analog with switchable contact interface, the behavior of which can be controlled simply by altering the surface temperature.

    更新日期:2017-11-20
  • Highly enhanced and stable activity of defect-induced titania nanoparticles for solar light-driven CO2 reduction into CH4
    Mater. Today (IF 21.695) Pub Date : 2017-11-20
    Saurav Sorcar, Yunju Hwang, Craig A. Grimes, Su-Il In

    Photocatalytic reduction of CO2 to fuel offers an exciting opportunity for helping to solve current energy and global warming problems. Although a number of solar active catalysts have been reported, most of them suffer from low product yield, instability, and low quantum efficiency. Therefore, the design and fabrication of highly active photocatalysts remains an unmet challenge. In the current work we utilize hydrogen-doped, blue-colored reduced titania for photocatalytic conversion of CO2 into methane (CH4). The photocatalyst is obtained by exposure of TiO2 to NaBH4 at 350 °C for 0.5 h. Sensitized with Pt nanoparticles, the material promotes solar spectrum photoconversion of CO2 to CH4 with an apparent quantum yield of 12.40% and a time normalized CH4 generation rate of 80.35 μmol g−1 h−1, which to the best of our knowledge is a record for photocatalytic-based CO2 reduction. The material appears intrinsically stable, with no loss in sample performance over five 6 h cycles, with the sample heated in vacuum after each cycle.

    更新日期:2017-11-20
  • From flat sheets to curved geometries: Origami and kirigami approaches
    Mater. Today (IF 21.695) Pub Date : 2017-11-16
    Sebastien J.P. Callens, Amir A. Zadpoor

    Transforming flat sheets into three-dimensional structures has emerged as an exciting manufacturing paradigm on a broad range of length scales. Among other advantages, this technique permits the use of functionality-inducing planar processes on flat starting materials, which after shape-shifting, result in a unique combination of macro-scale geometry and surface topography. Fabricating arbitrarily complex three-dimensional geometries requires the ability to change the intrinsic curvature of initially flat structures, while simultaneously limiting material distortion to not disturb the surface features. The centuries-old art forms of origami and kirigami could offer elegant solutions, involving only folding and cutting to transform flat papers into complex geometries. Although such techniques are limited by an inherent developability constraint, the rational design of the crease and cut patterns enables the shape-shifting of (nearly) inextensible sheets into geometries with apparent intrinsic curvature. Here, we review recent origami and kirigami techniques that can be used for this purpose, discuss their underlying mechanisms, and create physical models to demonstrate and compare their feasibility. Moreover, we highlight practical aspects that are relevant in the development of advanced materials with these techniques. Finally, we provide an outlook on future applications that could benefit from origami and kirigami to create intrinsically curved surfaces.

    更新日期:2017-11-20
  • Direct molecular interaction of CO2 with KTFSI dissolved in Pebax 2533 and their use in facilitated CO2 transport membranes
    J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-20
    Sungjin Lee, Seul Chan Park, Tea-Yon Kim, Sang Wook Kang, Yong Soo Kang

    Polymer electrolyte membrane containing potassium bis(trifluoromethanesulfonyl)imide (KTFSI) dissolved in a polymeric solvent of Pebax 2533 demonstrated facilitated transport for effective CO2 separation. Reversible interactions of CO2 with both K+ and TFSI- dissolved in Pebax 2533 were directly observed by both solid state 39K and 13C NMR and FT-IR spectroscopy for the first time, inducing the CO2 carrier activity for the facilitated transport. Additionally, through comparing the CO2 separation performance of LiTF2N, NaTF2N and KTF2N, it was concluded that alkali cation has play an important role in helping to interact with CO2 for the CO2 carrier activity and that K+ was the best as a CO2 carrier among alkali metals used. Consequently, the KTFSI/Pebax 2533 polymer electrolyte membrane showed significant improvement of the CO2 separation performance due to the carrier action of both K+ and TFSI- in the solid state with long-term stability.

    更新日期:2017-11-20
  • Module scale-up and performance evaluation of thin film composite hollow fiber membranes for pressure retarded osmosis
    J. Membr. Sci. (IF 6.035) Pub Date : 2017-11-20
    Yunfeng Chen, Chun Heng Loh, Lizhi Zhang, Laurentia Setiawan, Qianhong She, Wangxi Fang, Xiao Hu, Rong Wang

    Pressure retarded osmosis (PRO) demonstrates great potential in energy harvesting when combining with seawater reverse osmosis. However, the lack of suitable membrane modules and the issue caused by the membrane fouling greatly impede the practical application of PRO to a larger scale. In this study, two-inch thin film composite hollow fiber modules were fabricated by using in-house developed PRO membranes. The produced PRO modules have a maximum effective area of 0.5 m2. By assessing the PRO performances of the modules with different sizes, external concentration polarization (ECP) was found to have significant impact on the flux reduction during module scale-up. Different module designs, including fiber bundles, distribution baffles and distribution tubes, were thus adopted as an attempt to boost the membrane performance. A power density of 8.9 W/m2 at 15 bar was obtained using tap water as feed and 1 M NaCl solution as draw solution. PRO performance tests were also carried out using the developed two-inch modules on a pilot-scale setup with actual wastewater retentate as feed solution. Low pressure nanofiltration was selected as the pretreatment of the wastewater retentate to mitigate fouling. A power density of larger than 8 W/m2 was obtained when pretreated wastewater retentate was used as the feed solution, implying high potential of PRO in the pilot scale. Nevertheless, full potential of PRO can only be realized by mitigating ECP, which could be achieved by improving the module design in the further endeavor.

    更新日期:2017-11-20
  • Engineering detoxified pneumococcal pneumolysin derivative ΔA146PLY for self-biomineralization of calcium phosphate: Assessment of their protective efficacy in murine infection models
    Biomaterials (IF 8.402) Pub Date : 2017-11-20
    Jingwen Wu, Kaifeng Wu, Wenchun Xu, Taixian Yuan, Xiaofang Wang, Jinghui Zhang, Yajun Min, Yibing Yin, Xuemei Zhang

    Vaccine design ushered in the era of nanotechnology, as the vaccine is being developed toward particulate formulation. We have previously shown that the attenuated pneumolysin mutant (ΔA146PLY) was a safe and effective pneumococcal vaccine candidate. Here, to further optimize the formulation, we fused calcium phosphate (CaP) binding domains with ΔA146PLY so that the biocompatible CaP can mineralize with the protein automatically, allowing simple production of nanoparticle antigen during preparation. We fabricated four different nanoparticles, and then we compared the characteristics of different CaP-ΔA146PLY nanoparticles and demonstrated the influence of CaP binding domains on the size, shape and surface Ca/P ratio of the nanoparticles. It was found that these self-biomineralized CaP-ΔA146PLY nanoparticles varied in their capacity to induce BMDCs and splenocytes production of cytokines. We further demonstrated that, compared to free proteins, nanoparticle antigens induced more efficient humoral and cellular immune responses which was strong enough to protect mice from both pneumonia and sepsis infection. Also, the integration of CaP to protein has no significant impairment on body weight of animals, and subcutaneous infection of ΔA146PLY-peptides@CaP nanoparticles did not lead to the permanent formation of nodules in the skin relative to Alum adjuvant formulated antigens. Together, our data sufficiently suggest that soluble ΔA146PLY vaccine candidate could be processed into nanoparticles by self-biomineralization of CaP, the immunogenicity of which could be efficiently improved by the CaP binding domains.

    更新日期:2017-11-20
  • Ultra-low cost and highly stable hydrated FePO4 anodes for aqueous sodium-ion battery
    J. Power Sources (IF 6.395) Pub Date : 2017-11-17
    Yuesheng Wang, Zimin Feng, Dharminder Laul, Wen Zhu, Manon Provencher, Michel L. Trudeau, Abdelbast Guerfi, Karim Zaghib
    更新日期:2017-11-20
  • Gas explosions and thermal runaways during external heating abuse of commercial lithium-ion graphite-LiCoO2 cells at different levels of ageing
    J. Power Sources (IF 6.395) Pub Date : 2017-11-17
    Fredrik Larsson, Simon Bertilsson, Maurizio Furlani, Ingvar Albinsson, Bengt-Erik Mellander

    Commercial 6.8 Ah lithium-ion cells with different ageing/status have been abused by external heating in an oven. Prior to the abuse test, selected cells were aged either by C/2 cycling up to 300 cycles or stored at 60 °C. Gas emissions were measured by FTIR and three separate vents were identified, two well before the thermal runaway while the third occurred simultaneously with the thermal runaway releasing heavy smoke and gas. Emissions of toxic carbon monoxide (CO), hydrogen fluoride (HF) and phosphorous oxyfluoride (POF3) were detected in the third vent, regardless if there was a fire or not. All abused cells went into thermal runaway and emitted smoke and gas, the working cells also released flames as well as sparks. The dead cells were however less reactive but still underwent thermal runaway. For about half of the working cells, for all levels of cycle ageing, ignition of the accumulated battery released gases occurred about 15 s after the thermal runaway resulting in a gas explosion. The thermal runaway temperature, about 190 °C, varied somewhat for the different cell ageing/status where a weak local minimum was found for cells cycled between 100 and 200 times.

    更新日期:2017-11-20
  • Fuzzy model of residential energy decision-making considering behavioral economic concepts
    Appl. Energy (IF 7.182) Pub Date : 2017-11-20
    Constantine Spandagos, Tze Ling Ng

    To gain a fundamental understanding of the factors driving consumer energy behavior and for more effective policy-making, the development of energy consumption models taking into account key behavioral economic concepts is essential. In this direction, this paper presents a fuzzy logic decision-making model incorporating the concepts of bounded rationality, time discounting of gains, and pro-environmental behavior. The fuzzy model is used to characterize and predict consumer energy efficiency and curtailment behaviors in the context of residential cooling energy consumption. The model is developed from the perspective of the human decision-maker and the rules based on human reasoning and intuition. It takes into consideration monetary, personal comfort and environmental responsibility variables to yield predictions of one’s air-conditioning purchase and usage decisions. The results from running the model multiple times to simulate a real large urban population are found to match historical cooling energy use data reasonably well. This allows modelers some degree of confidence in the model. Moreover, perturbing key input variables produces plausible behaviors, thus providing additional validation to the model. This work demonstrates the feasibility of fuzzy logic as a powerful method for combining quantitative economic and physical factors with qualitative behavioral concepts in a single mathematical framework for better prediction of human energy behavior, and greater fundamental understanding of the “why” behind energy use that conventional building energy simulation models do not address.

    更新日期:2017-11-20
  • Influence of Capillary Die Geometry on Wall Slip of Highly Filled Powder Injection Molding Compounds
    Powder Technol. (IF 2.942) Pub Date : 2017-11-20
    Daniel Sanetrnik, Berenika Hausnerova, Petr Filip, Eva Hnatkova

    Uneven distribution of solid particles contained in the feedstocks used in the process of powder injection molding (PIM) is observed in the close vicinity of the walls. A particle-free thin layer adjacent to the walls is formed by the binder only and is characterized by so-called wall slip. Wall slip is a key to successful modeling of injection molding step of PIM. For its determination we used capillary rheometers equipped with the dies of different entrance angles applied to four PIM feedstocks. The entrance angle has been found to be a crucial parameter to intercept wall slip. Conical dies are more suitable to obtain reliable slip velocity values of highly filled compounds than capillaries having plane entrance, which are used in the majority of studies.

    更新日期:2017-11-20
  • Rapidly Catalysis of Oxygen Evolution through Sequential Engineering of Vertically Layered FeNi Structure
    Nano Energy (IF 12.343) Pub Date : 2017-11-20
    Gong Zhang, Guichang Wang, Huijuan Liu, Jiuhui Qu, Jinghong Li

    For practical hydrogen (H2) production via water electrolysis, large-scale design and fabrication of catalysts for high-efficiency electrochemical transformation of hydroxyl ions to oxygen in alkaline environment is of paramount importance to reduce energy losses. Using anodization, electroplating, and sequential electrodeposition, we herein realized a universal approach to vertically assemble 2D Fe-Ni hydroxide nanosheets on nickel foam surface as catalyst for oxygen evolution reaction (OER). The electrode exhibited OER onset overpotentials (η) of ~190 mV and a low η of ~270 mV at a current density of 100 mA cm−2 in KOH electrolyte, making it one of the most active OER catalysts reported so far. The FeNi films deposited via sequential deposition are highly ordered, and electrode is stable even under long term or large current density operation. Based on the results of theoretical calculation, dielectric force microscopy (DFM) analysis, and capacitance measurements, we found that 2D Fe-Ni hydroxide -loaded electrode with enhanced conductivity facilitates the sufficiently conversion of active sites and ensures optimal adsorption energies for intermediates of OER, as a result of structural effects as well as introduction of optimal amount of Fe on surface.

    更新日期:2017-11-20
  • LiFePO4 Quantum-Dots Composite Synthesized by a General Microreactor Strategy for Ultra-high-rate Lithium Ion Batteries
    Nano Energy (IF 12.343) Pub Date : 2017-11-20
    Bo Wang, Ying Xie, Tong Liu, Hao Luo, Bin Wang, Chunhui Wang, Lei Wang, Dianlong Wang, Shixue Dou, Yu Zhou

    Due to the relatively slow, diffusion-controlled faradaic reaction mechanisms of conventional LiFePO4 (LFP) materials, which is hard to deliver satisfied capacity for high rate applications. In this work, ultrafine LFP quantum dots (LFP-QDs) co-modified by two types of carbonaceous materials - amorphous carbon and graphitized conductive carbon (graphene) have been successfully synthesized through a novel microreactor strategy. Because of the very limited area constructed by the dual-carbon microreactor for the growth of LFP crystal, it's demension was furthest suppressed to a very small level (~ 6.5 nm). Such a designed nano-composite possesses a large specific surface area for charge adsorption and abundant active sites for faradaic reactions, as well as ideal kinetic features for both electron and ion transport, and thus exhibits ultra-fast, surface-reaction-controlled lithium storage behavior, mimicking the pseudocapacitive mechanisms for supercapacitor materials, in terms of extraordinary rate capability (78 mAh g−1 at 200 C) and remarkable cycling stability (~ 99% over 1000 cycles at 20 C). On the other side, due to the quasi-2D structure of the synthesized LFP-QDs composite, which can be used as the basic unit to further fabricate free-standing film, aerogel and fiber electrode without the addition of binder and conductive agent for different practical applications. In addition, to deeper understand its electrochemical behavior, a combined experimental and density functional theoretical (DFT) calculation study is also introduced.

    更新日期:2017-11-20
  • All-inorganic flexible piezoelectric energy harvester enabled by two-dimensional mica
    Nano Energy (IF 12.343) Pub Date : 2017-11-20
    Ding Wang, Guoliang Yuan, Gengqian Hao, Yaojin Wang

    A rapid surge in the research on self-powered bio-electronics is occurring toward the challenge that the state-of-the-art bio-devices require obsolete bulky batteries, which limit device miniaturization and lifespan. Among them, flexible piezoelectric materials that enable mechanical-to-electrical energy conversion, stimulate tremendous attraction to harvest mechanical energy from the motions of human and organs. Here, we report a cost-effective one-step process based on unique two-dimensional mica substrates to fabricate flexible piezoelectric energy harvesters, extending beyond prior art for all-inorganic flexible piezoelectric materials. As an exemplary demonstration, an all-inorganic, large scale, flexible piezoelectric Pb(Zr0.52Ti0.48)O3 energy harvester is fabricated with an outstanding performance (i.e., open-circuit voltage of 120 V, short-circuit current density of 150 μA cm-2 and power density of 42.7 mW cm-3), which are comparable to those via conventional “grow-transfer” technique from rigid substrates to organic soft ribbons, and are much greater by one to four orders of magnitude than previous reported ones based on piezoelectric nanofibers and organic thick films. In particular. This unique process provides a new perspective to fabricate all-inorganic piezoelectric energy harvesters for battery-free bio-electronics.

    更新日期:2017-11-20
  • Grain boundary transport in sputter-deposited nanometric thin films of lithium manganese oxide
    Nano Energy (IF 12.343) Pub Date : 2017-11-20
    Juliane Mürter, Susann Nowak, Efi Hadjixenophontos, Yug Joshi, Guido Schmitz

    The lithium intercalation into ion-beam sputter-deposited films of lithium manganese oxide is studied as a function of the film thickness (50 nm to 500 nm). The kinetics of the intercalation is quantified in cyclic voltammetry under variation of the scanning rate over five orders of magnitude (0.005 mV/s to 768 mV/s). With an increasing rate, the intercalation currents reveal a transition from a finite length diffusion to a semi-infinite diffusion behavior, as it is expected from continuum transport equations. But surprisingly, the peak current in the Randles-Sevcik regime scales with the square root of film thickness. Consequently, the diffusion coefficient apparently increases with the layer thickness. Combining the parameters of the actual microstructure of the thin films with an appropriate kinetic modeling that includes the effects of grain boundaries, it is shown that the observed acceleration is quantitatively understood by outstandingly fast short-circuit transport in a type B kinetic regime of grain boundary diffusion.

    更新日期:2017-11-20
  • NiO-induced synthesis of PdNi bimetallic hollow nanocrystals with enhanced electrocatalytic activities toward ethanol and formic acid oxidation
    Nano Energy (IF 12.343) Pub Date : 2017-11-20
    Zelin Chen, Jinfeng Zhang, Yuan Zhang, Yunwei Liu, Xiaopeng Han, Cheng Zhong, Wenbin Hu, Yida Deng

    Noble-metal hollow nanocrystals possess numerous unique advantages such as high surface-to-volume ratio and high utilization of noble metals, which make them a promising electrocatalyst for electro-oxidation of small molecules in fuel cells. Herein, we prepared bimetallic PdNi hollow nanocrystals (PdNi-HNCs) by taking advantage of the galvanic replacement reaction in an aqueous solution and developed a facile NiO-induced strategy for the controlled synthesis of PdNi-HNCs with dendritic or smooth outer shell architectures. A very short oxidation time of an amorphous Ni template is demonstrated to be the key factor to successful fabrication of the dendritic morphology. The results of electrochemical testing indicate that the electrocatalytic activities of PdNi-HNCs are highly dependent on their morphologies. The PdNi-HNCs with a rough and dendritic shell exhibit a mass activity of 1201.5 and 768.0 mA·mgPd−1 toward ethanol oxidation reaction (EOR) and formic acid oxidation reaction (FAOR), respectively, much greater than those of the commercial Pd black catalyst (502.6 and 266.3 mA·mgPd−1, respectivlely). In particular, the 1500 cyclic voltammetry cycles in alkaline solution and the 30000 s chronoamperometry tests in acid solution suggest an enhanced long-term durability of PdNi-HNCs with dendritic nanoarchitectures. We ascribe the better catalytic activity to the hollow feature, higher specific electrochemical surface area, more abundant active sites and more appropriate electronic structure of the PdNi-HNCs with a rough and dendritic shell.

    更新日期:2017-11-20
  • Photoresponsive self-assembly of a β-cyclodextrin derivative with an azobenzene terminal group in water
    Dyes Pigments (IF 3.473) Pub Date : 2017-11-20
    Huichuang Guo, Jingxuan Yang, Juntan Zhou, Lihan Zeng, Li Zhao, Baocai Xu

    We report the photoresponsive self-assembly of a β-cyclodextrin derivative containing an azobenzene terminal group with an oligoethylene glycol linker (Azo-EG-βCD). Azo-EG-βCD was synthesized, and its aggregation was investigated using several techniques including TEM analysis, DLS and other spectral measurements. In a freshly prepared aqueous solution, Azo-EG-βCD self-assembled into a network-like structure by forming intermolecular host–guest inclusions that transformed into vesicles upon aging because of hydrogen bonding. Transformation from trans-azo to cis-azo using UV light induced the dissociation of azobenzene in the β-CD cavity, and the aggregate transformed into vesicles. The construction of a photoresponsive self-assembly may provide a unimolecular host–guest complexation model in stimuli-responsive host–guest self-assembly.

    更新日期:2017-11-20
  • Removing of Direct Red 83:1 using α- and HP-α-CDs polymerized with epichlorohydrin: Kinetic and equilibrium studies
    Dyes Pigments (IF 3.473) Pub Date : 2017-11-20
    José Antonio Pellicer, María Isabel Rodríguez-López, María Isabel Fortea, José Antonio Gabaldón, Carmen Lucas-Abellán, María Teresa Mercader-Ros, Ana Serrano-Martínez, Estrella Núñez-Delicado, Pinalysa Cosma, Paola Fini, Esther Franco, Rocío García, Marcela Ferrándiz, Enrique Pérez, Miguel Ferrándiz

    The adsorption properties of two cyclodextrin-epichlorohydrin polymers to remove Direct Red 83:1 textile dye from wastewater solutions was evaluated. Adsorption studies were performed in a batch reactor, and the efficiency of the polymers under different parametric values such as contact time, adsorbent dosage, initial dye concentration, pH of initial solution and temperature was followed by spectrophotometry. Both Langmuir and Freundlich equations were used to fit the equilibrium isotherms and the kinetic data were analyzed by the pseudo-first-order and pseudo-second-order models. Adsorption process follows a pseudo-second-order kinetic and was influenced by intraparticle diffusion model, dye concentration and contact time, reaching equilibrium within the first 30 min. Experimental data were better fitted to Freundlich isotherm model than to Langmuir and Temkin isotherms. Since about 93% of dye removal was achieved under optimized conditions, the α-cyclodextrin-epichlorohydrin polymer seems to be a useful device for removing Direct Red 83:1 from aqueous solutions and industrial effluents.

    更新日期:2017-11-20
  • Preparation and characterization of ultrathin Pt/CeO2/Bi2WO6 nanobelts with enhanced photoelectrochemical properties
    Dyes Pigments (IF 3.473) Pub Date : 2017-11-16
    Qinyu Wang, Qifang Lu, Linbing Yao, Ke Sun, Mingzhi Wei, Enyan Guo

    One-dimensional ultrathin Pt/CeO2/Bi2WO6 nanobelts with an exceptional photoelectrochemical performance have been controllably and delicately fabricated via a simple two-step method. The as-prepared nanobelts were systematically characterized by TG, XRD, FT-IR, SEM, HRTEM, BET, XPS, UV-vis, PL, TOC, HPLC and EIS. The photocatalytic activity of resultant samples has been determined sufficiently through decomposition of methylene blue (MB) and rhodamine B (RhB) dyes. The enhanced photocatalytic performance is significantly improved by loading of Pt nanoparticles (NPs) on CeO2/Bi2WO6 nanobelts, and the optimal Pt content is also evaluated. In photocatalysis, the mechanism of ultrathin Pt/CeO2/Bi2WO6 nanobelts for the visible light photocatalytic enhancement is thoroughly elucidated. The nanobelts with such attributes could not only lead to the faster development for constructing highly efficient photocatalysts but also aid in our understanding and optimization of their properties.

    更新日期:2017-11-20
  • Electric field distribution and initial jet motion induced by spinneret configuration for molecular orientation in electrospun fibers
    Eur. Polym. J. (IF 3.531) Pub Date : 2017-11-20
    Xiang Li, Jinyou Lin, Yongchun Zeng

    Understanding the molecular orientation of electrospun fibers is a key challenge for tailoring fiber properties. The studies of electric field distribution, and the motion of the initial portion of the polymer jet, are of interest for clarifying molecular orientation in fibers during electrospinning. In this work, we study the impact of electric field distribution and the initial jet motion induced by two kinds of spinneret configurations, referred to as a needle configuration and a hole configuration, on molecular orientation in electrospun PEO fibers. Using FE-SEM, FTIR and WAXD techniques, the fiber diameter and molecular orientation of the fibers prepared with the needle electrospinning system and the hole electrospinning system are characterized. To explore jet stretching and chain orientation during the spinning process, electric field simulation and high-speed photography are performed to obtain the electric field characteristics and to measure the initial jet velocities for the needle and the hole systems. Our results reveal the higher electric field strength around the spinneret and the larger initial jet velocities, which depend on the spinneret configuration, result in the higher degree of molecular orientation in fibers.

    更新日期:2017-11-20
  • Time resolved characterization of the solid-state reaction between polycarbonate and primary amine
    Eur. Polym. J. (IF 3.531) Pub Date : 2017-11-20
    Cordelia Zimmerer, Lisa Ziegler, Gert Heinrich, Gerald Steiner

    Polycarbonate can be functionalized with specific moieties such as amino groups. A novel approach for functionalization is based on a process integrated surface modification, e.g. during the injection molding process. However, the solid-state reaction routes are complex, not well investigated and difficult to control. In this study the solid state reaction of polycarbonate with octadecylamine was studied by using infrared spectroscopy and 2D correlation analysis. The infrared spectrum taken after 20 minutes reaction time shows the formation of urethane as an interfacial linker between polycarbonate and octadecylamine. Furthermore, bisphenol-A, also formed initially, indicates a degradation of polycarbonate. The solid-state reaction during 360 minutes processing time was investigated by 2D correlation analysis. The 2D correlation maps indicate a progress in the degradation of polycarbonate and the formation of biuret and urea. No more urethane is formed during longer processing time. This study demonstrates that a surface modification of polycarbonate with octadecylamine requires a very short reaction time in order to ensure an optimized interfacial link and to minimize the degradation of the materials.

    更新日期:2017-11-20
  • Electron-induced reactive processing of polyamide 6/polypropylene blends: Morphology and properties
    Eur. Polym. J. (IF 3.531) Pub Date : 2017-11-20
    Shib Shankar Banerjee, Andreas Janke, Uwe Gohs, Gert Heinrich

    Electron-induced reactive processing (EIReP) recently has appeared as an advanced processing technology to modify several polymer compounds at melt state by its spatial and temporal precise energy input. In the present work, an attempt was made to prepare a compatible blend from polar polyamide 6 (PA6) and non-polar polypropylene (PP) using EIReP without any chemical crosslinking and chemical additives. EIReP modified blends were prepared at different doses (5, 10 and 20 kGy) and dose per revolutions (3, 6 and 12 kGy/rev) while keeping constant the values of mass ratio (50/50 w/w), electron energy (1.5 MeV), rotor speed (60 rpm) and temperature (230 °C). EIReP process parameters-morphology-property relationship of this blend was studied. Interestingly, co-continuous morphology of the blend was converted to droplet-matrix morphology after EIReP whether PA6 was continuous phase. Influence of dose on the DMT modulus (Derjaguin-Muller-Toporov) at different phases of the blends was also measured and analyzed using advanced PeakForce Quantitative Nanomechanical Mapping atomic force microscopy (AFM) technique. Improved nano- and macroscopic properties of EIReP modified blends were originated from the properties of the continuous matrix phase, electron-induced branching and also from the reduction of domain size of PP phase with increased dose.

    更新日期:2017-11-20
  • Mechanical properties and thermal characteristics of poly(lactic acid) and paraffin wax blends prepared by conventional melt compounding and sub-critical gas-assisted processing (SGAP)
    Eur. Polym. J. (IF 3.531) Pub Date : 2017-11-20
    Yann-Jiun Chen, An Huang, Thomas Ellingham, Chunhui Chung, Lih-Sheng Turng

    In this study, poly(lactic acid) (PLA)/paraffin wax (PW) blends containing different amounts of PW were investigated. The blends were prepared by a twin-screw extruder using two different methods: conventional melt compounding extrusion and sub-critical gas-assisted processing (SGAP). Then, the blends and neat PLA were injection molded into ASTM 638 Type V tensile bars for evaluation. To observe the effects of the different melt compounding processes and the effects of paraffin wax added to the blends, the rheological properties, crystallization behavior, and thermal stability of the extruded blends, as well as the phase morphology and tensile properties of the injection molded tensile bars, were characterized. The results showed that the addition of paraffin wax yielded tremendous improvements in elongation compared to neat PLA. In addition, samples made by the sub-critical gas-assisted processing (SGAP) extrusion method exhibited more homogeneous phase morphologies and paraffin wax dispersion, better tensile properties and thermal stability, and more consistent material properties as compared to their conventionally compounded counterparts.

    更新日期:2017-11-20
  • Water-actuated shape-memory and mechanically-adaptive poly(ethylene vinyl acetate) achieved by adding hydrophilic poly (vinyl alcohol)
    Eur. Polym. J. (IF 3.531) Pub Date : 2017-11-20
    Zhi-xing Zhang, Xiao-dong Qi, Song-tai Li, Jing-hui Yang, Nan Zhang, Ting Huang, Yong Wang

    Water-actuated shape memory polymers (SMPs) have great potential applications in many fields. Although many strategies have been developed to endow polymers with water-active shape memory effect (SME), so far it is still challenging to prepare the water-actuated SMPs with a highly sensitive SME in a method as facile as possible. In this work, poly(vinyl alcohol) (PVA) was incorporated into poly(ethylene vinyl acetate) (EVA) through the simple solution compounding processing. The blends exhibited good interfacial interaction on one hand. On the other hand, PVA exhibited excellent reinforcement effect, leading to the great enhancement of modulus and strength. Further results showed that the samples had excellent water uptake and dehydration abilities, and the presence of water resulted in the dramatic decrease of modulus and large increase of tensile ductility, which endowed the materials with great potential to realize complicated deformation at gentle force. The water-active SME was evaluated through cycling measurements, i.e. wetting-stretching-drying processes. The results showed that the water-active SME of the blends was greatly dependent upon the blend compositions. After several cycling measurements, the water-active SME of samples became stable. Specifically, for the sample containing 35 wt% PVA, the shape fixity and shape recovery ratios were increased up to 98.7% and 99.5%, respectively. The mechanisms for the excellent water-active SME were then discussed.

    更新日期:2017-11-20
  • Improved Antiviral Properties of Chain End Lipophilic Fucoidan-Mimetic Glycopolymers Synthesized by RAFT Polymerization
    Eur. Polym. J. (IF 3.531) Pub Date : 2017-11-20
    Mattias Tengdelius, Cheung Kwan Yee, May Griffith, Peter Påhlsson, Peter Konradsson

    Sulfated polysaccharides and synthetic glycopolymers are promising candidates as antiviral drugs but have failed in clinical trials most likely due to lack of virucidal activity. However, studies have shown that incorporation of lipophilic end groups to oligosaccharide chains is a mean to gain the desired virucidal properties. Here, we describe the introduction of lipophilic end groups to sulfated α-L-fucoside-pendant polymethacrylamides, also known as fucoidan-mimetic glycopolymers, by RAFT polymerization. RAFT agents bearing octadecyl, dioctadecyl and cholesteryl groups were used to synthesize lipoglycopolymers of different chain lengths. Short lipoglycopolymers bearing lipophilic end groups showed an improved ability to block viral entry and infection of cells compared to glycopolymers without lipophilic end groups. Short lipoglycopolymers bearing octadecyl or dioctadecyl end groups, also completely stopped the spreading of the viral infection. However, these lipoglycopolymers did not show actual virucidal properties. Nevertheless, we have described a first step towards obtaining virucidal synthetic glycopolymers for clinical use.

    更新日期:2017-11-20
  • Structure and performances changes during tensile of aromatic copolysulfonamide fibers under different thermal temperatures via in-situ Synchrotron SAXS/WAXS
    Eur. Polym. J. (IF 3.531) Pub Date : 2017-11-17
    Xiaoyun Li, Jinchao Yu, Jianning Wang, Kang Chen, Xiuhong Li, Yumei Zhang, Fenggang Bian, Jie Wang

    In situ studies of structure and performance changes in aromatic copolysulfonamide (co-PSA) fibers during stretching at different thermal exposure temperature range from room temperature to 300°C were carried out using synchrotron small angle X-ray scattering and wide angle X-ray scattering techniques. Results showed that the optimum microstructure and mechanical property of co-PSA fibers were achieved when stretched at 200°C, the fibril length, fibril misorientation, crystal sizes L002 reached minimum, the long period became maximum at the same strain indicating that lamella and fibrils aligned perfectly, fiber structure compactness at 200°C. During stretching at RT to 200°C, at low strain, fibril length, crystal size L002 increased, fibrils oriented along stretching direction, the long period was enlarged; the opposite trend evolution of structure appeared under high strain. But stretching at 300°C, L002 increased, fibril orientation became poor, the lamellae destroyed easily resulting in the decreasing strength. It can be concluded that co-PSA fibers remain good property under thermal at 200°C, external force use environment.

    更新日期:2017-11-20
  • The structure and magnetic properties of pure single phase BiFeO3 nanoparticles by microwave-assisted sol-gel method
    J. Alloys Compd. (IF 3.133) Pub Date : 2017-11-20
    Shuai Zheng, Jiangying Wang, Jingji Zhang, Hongliang Ge, Zhi Chen, YaFeng Gao

    The pure single phase BiFeO3 nanoparticles have been prepared by microwave-assisted sol-gel process and its structure and magnetic properties have been studied. X-ray diffractometer, infrared and transmission electron microscope results show that the synthesized BiFeO3 nanoparticles at the calcining temperature of 450 °C exhibits a rhombohedrally distorted perovskite structure without secondary phase and the size is about 40 nm. Meanwhile, the pure single phase BiFeO3 particles exhibit typical ferromagnetic properties at room temperature and the obvious large exchange bias phenomenon at 60 K. A exchange bias field (HE) of 302 Oe at 60 K for pure single phase BiFeO3 nanoparticles at calcining temperature 450 °C after field cooling at 20 KOe has been observed. The MT curve at H = 100 Oe shows that the FC and ZFC magnetization curves start to differ in the temperature range from 60 K to 300 K revealing spin glass behavior of BiFeO3 nanoparticles at calcining temperature 450 °C, 500 °C and 550 °C. The ferromagnetic behavior is attributed to size of effects, which partially destroy the long-wavelength cycloid spin structure expected in bulk BiFeO3. The exchange bias effect in single crystalline BiFeO3 nanoparticles arises from co-existence of different magnetic phases of an antiferromagnetic core and a ferromagnetic surface. The ferromagnetic, exchange bias effect and spin glass behavior of BiFeO3 nanoparticles are assigned to the uncompensated or canted spins at the ferromagnetic surface and an antiferromagnetic core of BiFeO3 nanoparticles.

    更新日期:2017-11-20
  • Core-shell Fe3O4@Fe ultrafine nanoparticles as advanced anodes for Li-ion batteries
    J. Alloys Compd. (IF 3.133) Pub Date : 2017-11-16
    Yuepeng Pang, Jing Wang, Zhiguo Zhou, Tao Yuan, Junhe Yang, Dalin Sun, Shiyou Zheng

    Core-shell Fe3O4@Fe ultrafine nanoparticles (nano-Fe3O4@Fe, Fe3O4 content 84 wt%) with a core (Fe) diameter of 5.1 ± 1.4 nm and a shell (Fe3O4) diameter of 10.9 ± 1.6 nm is prepared by a liquid-phase pyrolysis and partial oxidation method. It is found that the core-shell Fe3O4@Fe ultrafine nanostructure can efficiently improve the electrochemical performance of Fe3O4 as anode material for Li-ion batteries in terms of rate capability and cycle life. For instance, specific capacities of 884 and 705 mAh/g can be obtained for the nano-Fe3O4@Fe electrode after 100 cycles at 200 mA/g and 500 cycles at 1000 mA/g, respectively. It is believed that these improvements can be attributed to the significant shortened transfer distance of electrons and Li-ions with relatively low specific surface area, ultrahigh electronic conductivity inside the nanoparticles and good ductility to accommodate the asymmetric volume change.

    更新日期:2017-11-20
  • Preparation, microstructure, and microstructure-properties relationship of thermoplastic vulcanizates (TPVs): A review
    Prog. Polym. Sci. (IF 25.766) Pub Date : 2017-11-20
    Nanying Ning, Shangqing Li, Hanguang Wu, Hongchi Tian, Pengjun Yao, Guo-Hua Hu, Ming Tian, Liqun Zhang

    It is common practice to blend polymers to obtain high-performance polymer materials for new applications. Thermoplastic vulcanizates (TPVs), consisting of a high content of crosslinked rubber as a dispersed phase and a low content of thermoplastic as a continuous phase, are usually prepared by pre-blending rubber and plastic phases followed by dynamic vulcanization. They are a special class of high performance thermoplastic elastomers (TPEs) as they combine both the excellent elasticity and mechanical properties of crosslinked rubbers and good processability and recyclability of thermoplastics. As such, in the recent decades they have attracted much attention and have become the fastest growing elastomers to replace unrecyclable thermoset rubbers. This review focuses on recent progresses in TPVs, and more specifically on the following issues: (1) preparation methods of TPVs, (2) mechanisms of formation of the microstructure of TPVs; (3) relationships between the microstructure and properties, (4) review of various types of TPVs, including general TPVs, special TPVs, bio-based TPVs, and TPVs-based nanocomposites, (5) future challenges on TPVs.

    更新日期:2017-11-20
  • The tensile behaviors of vanadium-containing 25Cr-20Ni austenitic stainless steel at temperature between 200 ℃ ℃ and 900 °C
    Mater. Sci. Eng. A (IF 3.094) Pub Date : 2017-11-20
    Guodong Hu, Pei Wang, Dianzhong Li, Yiyi Li

    The high-temperature tensile behaviors of two 25Cr-20Ni austenitic stainless steels with different V concentration (0 wt. % V and 0.3 wt. % V, respectively), have been studied at temperature between 200 ℃ ℃ and 900 ℃ ℃ . The ultimate tensile strength of both steels is strong temperature dependent, which decreases slowly first at 200–300 ℃ ℃ , keeps platform then at 300–500 ℃ ℃ and decreases rapidly afterwards from 600 ℃ ℃ to 900 ℃ ℃ . It is caused by the decreasing strain hardening ability, dynamic strain aging and dynamic recovery together with dynamic recrystallization at different temperatures. At higher than 800 ℃ ℃ , the elongation of both steels increases markedly due to the dynamic recovery and dynamic recrystallization. However, because of the deteriorated effects of M23C6 precipitates at grain boundary, the elongation of both steels at 700 ℃ ℃ does not increase despite decreasing strength. Additionally, the addition of 0.3 wt. % V decreases the ductility of the material in the temperature range of 800 ℃ ℃ to 900 ℃ ℃ , which is induced by the impeding effects of solute vanadium on dynamic recovery and recrystallization.

    更新日期:2017-11-20
  • Microstructure and mechanical properties of a heat-treatable Al-3.5Cu-1.5Mg-1Si alloy produced by selective laser melting
    Mater. Sci. Eng. A (IF 3.094) Pub Date : 2017-11-20
    Pei Wang, Christoph Gammer, Florian Brenne, Konda Gokuldoss Prashanth, Rafael Gregorio Mendes, Mark Hermann Rümmeli, Thomas Gemming, Jürgen Eckert, Sergio Scudino

    A heat-treatable Al-3.5Cu-1.5Mg-1Si alloy is successfully fabricated by selective laser melting and is investigated concerning microstructures and mechanical properties. The as-prepared samples show a fine-granular microstructure in the individual melt pool of the tracks and a coarse-granular microstructure in the areas between the tracks. After T6 heat treatment, the grain size of the specimens increases slightly and the Q phase formed in the as-prepared specimens transforms to Al2Cu(Mg), Mg2Si, and AlxMny. All Al-Cu-Mg-Si specimens before and after heat treatment fracture around the defects that were generated during processing and show intergranular fracture along columnar grains upon tensile quasi-static loading. The as-fabricated samples exhibit a yield strength (YS) of 223 ± 4 MPa and an ultimate tensile strength (UTS) of 366 ± 7 MPa with an elongation of 5.3 ± 0.3%. After T6 heat treatment, the YS and UTS increase dramatically to 368 ± 6 MPa and 455 ± 10 MPa due to the formation of nano-sized Al2Cu(Mg) precipitates, respectively, while the ductility remain fairly similar.

    更新日期:2017-11-20
  • Precipitate Strengthening and Thermal Stability in Three Component Metallic Nanolaminate Thin Films
    Mater. Sci. Eng. A (IF 3.094) Pub Date : 2017-11-20
    R.L. Schoeppner, A.A. Taylor, M.J. Cordill, H.M. Zbib, J. Michler, D.F. Bahr

    Cu/Ni/Nb tri-layer and CuNi/Nb alloy multilayer films were annealed to examine the microstructural evolution and mechanical properties of three component laminated metallic nanostructures. Scanning transmission electron microscopy showed NixNby compounds forming on either side of the Nb layer in both tri-layer and alloy films. Post annealing nanoindentation showed all annealing conditions resulted in increased hardness, indicative of the NixNby intermetallic phase increasing the hardness of the films. The hardness of both films achieves a maximum hardness after annealing for 3 hours at 300 °C. The hardness increase as the annealing temperature increases corresponds to a thicker NixNby layer at the incoherent boundary. This strengthening technique could be implemented in a variety of different multilayer systems to achieve age-hardenable multilayer metallic nanostructures.

    更新日期:2017-11-20
  • Effect of hot cross rolling on the microstructure and mechanical properties of an Fe-14Cr ODS ferritic steel
    Mater. Sci. Eng. A (IF 3.094) Pub Date : 2017-11-20
    J. Macías-Delgado, T. Leguey, V. de Castro

    Oxide dispersion strengthened (ODS) reduced activation ferritic steels are leading candidates to become part of the structure of the first wall/blanket of future fusion reactors. Their major drawback is their poor toughness, which must be improved. In this work, an ODS ferritic steel having nominal composition Fe–14Cr–2W–0.2Ti–0.55 Fe2Y (wt.%), produced by mechanical alloying of prealloyed powders with Fe2Y intermetallic particles and consolidated by hot isostatic pressing, was subjected to either thermal treatments at high temperature or hot cross rolling in an attempt to investigate the effectiveness of such post-consolidation thermomechanical treatments. Its microstructure, nanoparticle dispersion and mechanical properties were analysed and correlated on each condition. As compared with the annealing treatments hot cross rolling led to a significant decrease in the grain size as well as a slight decrease in the size of some of the secondary phases present in the material. Also, the impact and tensile behaviour was improved over the whole temperature range studied.

    更新日期:2017-11-20
  • Misorientation, grain boundary, texture and recrystallization study in ×90 hot bend related to mechanical properties
    Mater. Sci. Eng. A (IF 3.094) Pub Date : 2017-11-20
    Liang Wang, Bin Wang, Peishan Zhou

    In the present study, electron backscattering diffraction (EBSD) was used to study the relationship between misorientation, grain boundary, texture, recrystallization and the mechanical properties for API (American Petroleum Institute) ×90 hot induction bend. The experimental results show that the yield strength of the parent pipe is 748 MPa, while it reduced about 40 MPa after hot induction bending. The strength in the inner arc side is similar along the longitudinal and transverse direction, but it is anisotropic in the outer arc side. The texture of {113} <110> components and {112} <110> components are the main reason for anisotropy. After hot induction bending, the deformed and elongated grains exist in the bend zone of ×90 bend, and the sub-grain boundaries exist in the grains. The grains in the neutral axis are equiaxed and without lath-like structure and sub-structure. A large fraction of lath bainite (LB) boundaries and Σ3 boundaries in the outer arc side resulted in a high strength and low impact toughness. Moreover, the deformed region and the recrystallization region have the same tendency for the tested specimens, the neutral axis of ×90 bend has a lower stored energy in the grains that could resist the cracks propagation effectively.

    更新日期:2017-11-20
  • Vacancy effects on the mechanical behavior of B2-FeAl intermetallics
    Mater. Sci. Eng. A (IF 3.094) Pub Date : 2017-11-20
    M. Zamanzade, G. Hasemann, C. Motz, M. Krüger, A. Barnoush

    The present work addresses the impact of quenched-in thermal vacancies on the mechanical properties of B2 iron aluminides. For this reason different binary Fe-Al alloys with different histories of heat treatment were indented at room temperature. The contributions of mono- and bi-vacancies in addition to triple defects on the elastic, plastic and elastic-plastic transition were evaluated using nanoindentation technique. In the samples containing bi-vacancies, the increase of the hardness was much more pronounced compared to the mono-vacancies.

    更新日期:2017-11-20
  • On the Strain Rate Sensitivity of Aluminum-containing Transformation-Induced Plasticity Steels: Interplay between TRIP and TWIP Effects
    Mater. Sci. Eng. A (IF 3.094) Pub Date : 2017-11-20
    K. Li, Y.S.Y. Injetti, R.D.K. Misra, Z.H. Cai, H. Ding

    The primary objective of the study is to elucidate the effect of strain rate on the deformation behavior of Al-containing transformation-induced plasticity steels (TRIP) via combination of depth-sensing nanoindentation experiments and post-mortem analyses of deformed steels using transmission electron microscopy (TEM). The strain rate sensitivity decreased with increased Al-content. The activation volume of 2Al-steel was ~ half (6 b3) of 6Al-steel (11 b3), where b is the magnitude of the Burgers vector. The strain rate influenced the evolution of strain-induced martensite (TRIP effect), dislocation slip and deformation twinning (TWIP effect). The interplay between TRIP and TWIP effects as a function of strain rate is analyzed and discussed in terms of the three internal energies, namely γ→α (austenite→martensite) transformation Gibbs free energy, strain energy and stacking fault energy. These were impacted by the Al-content of the steels, which altered the austenite stability and propensity to deformation twinning. The study provides insights into the design of next generation of TRIP steels for the fabrication of automotive components.

    更新日期:2017-11-20
  • Creep properties, creep deformation behavior, and microstructural evolution of 9Cr-3W-3Co-1CuVNbB martensite ferritic steel
    Mater. Sci. Eng. A (IF 3.094) Pub Date : 2017-11-17
    Bo Xiao, Lianyong Xu, Lei Zhao, Hongyang Jing, Yongdian Han, Yu Zhang

    Creep deformation behavior and microstructure evolution of G115 steel were systematically investigated for temperatures of 625–675 °C under uniaxial tensile stress of 120–220 MPa. The relationship between minimum creep rate and applied stress followed the Bird–Mukherjee–Dorn (BMD) equation. The modified BMD equation was proposed using threshold stress to elucidate the actual creep deformation mechanism. The values of the threshold stress were determined to be 177.8, 91.4 and 87.6 MPa at 625, 650, and 675 °C, respectively. The true creep activation energy and the true stress exponent were 275.76 kJ/mol and 6, respectively. Thus, the dominant creep deformation mechanism was identified as dislocation climb. Three types of precipitates can be revealed after creep deformation: W-rich Laves, Nb-rich MX, and Cu-rich phases. The creep damage of G115 steel after creep deformation was characterized by martensite cracks and martensite fractures owing to the hardness and brittleness of the lath martensite structure. Further, a dense array of deep and equiaxed dimples appeared in the central region of fracture surfaces under the tested creep conditions. Ductile fracturing was the main fracture mechanism during creep deformation.

    更新日期:2017-11-20
  • Microstructure Evolution and Enhanced Mechanical Properties in SUS316LN Steel Processed by High Pressure Torsion at Room Temperature
    Mater. Sci. Eng. A (IF 3.094) Pub Date : 2017-11-17
    Shouwen Shi, Zhe Zhang, Xiaobin Wang, Gaobin Zhou, Guofu Xie, Da Wang, Xu Chen, Kei Ameyama

    Nowadays, it is of interest to enhance the strength of metals for light-weight design of nuclear reactor, so the objective of the present study is to improve the mechanical properties of SUS316LN steel through grain refinement. The nanostructured SUS316LN steels were produced by high pressure torsion (HPT) at room temperature. The variations of microstructure and strain-induced martensite transformation during HPT were investigated. The homogeneous nanostructured SUS316LN steel with an average grain size of approximately 40 nm was achieved by HPT for 5 revolutions under a pressure of 5 GPa, which demonstrated extremely high tensile strength (1828MPa) and high hardness (530HV). The interstitial nitrogen atoms can reduce the stacking fault energy of the material and also play an important role in interaction with mobile dislocations during HPT. Therefore, compared to SUS316L steel, the formation of the nanograined structure was much faster and the strain-induced martensite transformation was restrained in the HPT-produced SUS316LN steel.

    更新日期:2017-11-20
  • Basic creep modelling of aluminium
    Mater. Sci. Eng. A (IF 3.094) Pub Date : 2017-11-16
    S. Spigarelli, R. Sandström

    In recent years a basic creep model that does not involve adjustable parameters has been developed. The main feature of this model is that it is fully predictable and the assumptions at its basis can be easily verified once the output is compared with experimental data. This model, initially developed for pure copper, has been here applied to pure aluminium. A critical issue has been identified with the controlling mechanisms during power-law breakdown. The increase in the creep rate at high stresses and low temperatures can be quantitatively explained from the raised climb rate due to the deformation-induced increase in concentration of vacancies. The model can also account for the fairly wide range of stresses where aluminium follows power-law creep with a creep exponent of 4 to 5. At slightly lower stresses, the creep exponent increases somewhat due to the presence of an internal stress. Since no adjustable parameters have been required, the model represents a notable enhancement over the conventional approach, which is based on the use of the power-law equation and requires fitting of experimental data to determine the values of the material parameters.

    更新日期:2017-11-20
  • The dynamic mechanical characteristics of Zr-based bulk metallic glasses and composites
    Mater. Sci. Eng. A (IF 3.094) Pub Date : 2017-11-16
    G.J. Lyu, J.C. Qiao, J.M. Pelletier, Y. Yao

    In the current study, Zr-based metallic glass matrix composites (MGMCs) were prepared by doping high-melting point of tantalum powders and investigated by dynamic mechanical analysis. The results suggest that the relaxation processes are changed by modifying the chemical composition. The influence of crystalline phase on the dynamic mechanical response of Zr-based MGMC has been analyzed. The master curves of loss modulus can be well fitted by the Kholrausch-Williams-Watts (KWW) model, decreasing of the parameter βKWW β KWW implies that the Zr-based MGMC doped with more tantalum powders has higher dynamic heterogeneity. To better understand the dynamic mechanical properties of the MGMCs, quasi-point defects (QPD) theory is adopted, the kinetic characteristics of glass transition of Zr-based MGMCs are analyzed in a quantitative manner. The experimental results provide an insightful information on the complex structural relaxation of the metallic glass matrix composite.

    更新日期:2017-11-20
  • High strength, ductility, and electrical conductivity of in-situ consolidated nanocrystalline Cu-1%Nb
    Mater. Sci. Eng. A (IF 3.094) Pub Date : 2017-11-16
    Khaled M. Youssef, Mohamed A. Abaza, Ronald O. Scattergood, Carl. C. Koch

    Nanocrystalline metals—with grain sizes less than 100 nm— have strengths exceeding those of coarse-grained and even alloyed metals 1 ; 2. A bulk nanocrystalline Cu-1%Nb alloy was synthesized by an in-situ consolidation mechanical alloying technique. The mechanical behavior of this alloy was investigated by hardness and tensile tests. The nanostructure was investigated by X-ray diffraction and transmission electron microscopy and the fracture surface by scanning electron microscopy. Electrical resistivity was measured using a four-point probe technique. The dilute additives of Nb and the processing conditions induced artifact-free bulk nanocrystalline materials that possess extraordinary high strength, good ductility, and high electrical conductivity.

    更新日期:2017-11-20
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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