Current Issue |
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May 15,2014 Volume 7,Issue 9 Pages - Subject Area:Foundational Subject in Materials Science,Composite Materials |
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Title: Diffusive transformation at high strain rate: instant dissolution of precipitates in aluminum alloy during adiabatic shearing deformation | ||||
Authors: YANG Yang, LUO Shuhong, CHEN Peixian, HU Haibo, TANG Tiegang, ZHANG Qingming, ZHANG Xiaowei PP: 897-907 Abstract: Dynamic testing of 2195-T6 aluminum lithium alloy was carried out in a hat-shaped specimen by a split Hopkinson pressure bar (SHPB) at ambient temperature. The microstructure and phase transformation in dynamic shear deformation band produced in 2195-T6 aluminum lithium alloy were investigated by means of optical microscopy (OM) and transmission electron microscopy (TEM). The results showed that the fine equiaxed grains were formed in adiabatic shear band (ASB), and the diffusive transformation took place during adiabatic shearing deformation, namely the precipitates existed in the matrix of aluminum alloy before loading were instantly dissolved into matrix. The thermodynamics and kinetics of instantaneous dissolution of the precipitates during adiabatic shearing were firstly investigated, and a dissolution model considering the factor of perturbation was established in the present work. Keywords: basic subject of material science; 2195 aluminum lithium alloy; adiabatic shearing deformation; instant dissolution of precipitates |
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Title: Influence of sliding velocity on the wear property of microarc oxidation film on AZ31 magnesium alloy | ||||
Authors: XU Baoku, HAN Xiaoguang PP: 892-896 Abstract: A uniform microarc oxidation (MAO) film was prepared on the surface of AZ31 magnesium alloy in silicate solution electrolyte. The dry sliding wear behavior of the MAO film was carried out on a WTM-2E tribological machine. The phases and microstructure were identified and observed by using X-ray diffraction(XRD) and scanning electron microscopy(SEM). The MAO film was mainly composed of MgO and Mg2SiO4. Both the weight loss and friction coefficient of MAO film decreased with the increase of sliding velocity, and the friction coefficient fluctuated from 0.9 to 1.1. The friction coefficient of the worn film was close to that of the matrix alloy. Abrasion is the main mechanism for the MAO film Keywords: failure and protection of material; sliding wear; AZ31 magnesium alloy; microarc oxidation film; sliding velocity |
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Title: Research on pyrolysis of furfural residue and preparation of activated carbon with high absorbing ability | ||||
Authors: LI Pengfei, YANG Qiaowen, CHEN Si, BIAN Chengchen PP: 887-891 Abstract: In this experiment, suitable carbonization conditions were decided by thermogravimetric (TG) analysis of furfural residue under the condition of nitrogen: temperature is 450℃, carbonization time is 1 h. The composition and content of pyrolysis gas under different conditions were analyzed, with the result that contents of hydrogen, carbon oxide and methane have varying degrees of increase with the increase of pyrolysis temperature. The influence of activation temperature, activation time, and water vapor flux on activated carbon was studied, too. Conclusion can be drawn that the optimal technological condition is that activation temperature is 850℃, activation time is 3.0 h, and water vapor flux is 0.90 kg/(kg furfural residue·h). In this condition, the iodine adsorption value is 946.80 mg/g, the methylene blue adsorption value is 296.56 mg/g, yield is 20.30%. Keywords: material synthesis and processing technology; activated carbon; furfural residue; thermogravimetric analysis; pyrolysis |
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Title: Application of hydrothermal carbon-based composite in surface enhanced Raman scattering | ||||
Authors: HUANG Wei, FAN Tongxiang PP: 881-886 Abstract: In this study, we synthesized Ag@hydrothermal carbon(HTC)/Ag composites through hydrothermal carbonization-in situ reduction method and explored the surface enhanced Raman scattering(SERS) behavior of the composites to Rhodamine 6G (R6G). Results showed that the composites were highly active and the detection limit of R6G could be as low as 10-11 mol/L. The composites can detect low concentration molecules with high sensitivity. Keywords: composite material; hydrothermal carbonization; Rhodamine 6G; surface enhanced Raman scattering |
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Title: Synthesis and plasma resonance absorption of Ag dendrite nanoparticles | ||||
Authors: CHEN Boting, DONG Biao PP: 876-880 Abstract: In this paper, we present a simple synthesis of Ag dendrite structures through a polyvinyl alcohol (PVA)-AgNO3 composite system under high voltage. These materials own good plasmon absorption in near infrared (NIR) region due to the orientated growth of Ag. The structures are confirmed by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) spectrum. The morphology of the Ag particles and the corresponding surface plasma resonance absorption show that the Ag torus is the key role for the NIR absorption. The results of scanning electron microscopy (SEM) detections show that, by controlling the ratio of PVA to AgNO3 and the spin rate, the Ag dendrite can be obtained and the bands of Ag film can be tuned from visible to 810 nm. Keywords: composite material; Ag; dendrite structure; plasma resonance |
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Title: Porosity effect on Young’s modulus based on ultrasound vibrometry | ||||
Authors: WANG Chengcheng, LIN Jiangli, CHEN Ke, YIN Guangfu PP: 871-875 Abstract: Based on ultrasound vibrometry, combined with the finite element numerical simulation, this paper incentives the non-porous solid material to vibrate in response to the acoustic signal, and gets its acoustic response signal, and then compares with the response signal of the above entity material with pores. On this basis, the non-porous solid material Young’s modulus is adjusted to make the smallest difference between the two acoustic response signals, on this account the effective Young’s modulus of the porous material is calculated. The above-mentioned simulation experiment is replicated with the changes of the quantity and distribution of pores. The study reveals the effective Young’s modulus of the porous material with a uniform distribution decreases with increasing pores, which has a certain regularity. And the change of the multiple pores to the effective Young’s modulus is equal to the sum of the variation of individual pore. This provides the possibility for the non-destructive testing porosity of scaffold. Keywords: special function inorganic nonmetal material; ultrasound vibrometry; tissue engineering scaffold material; finite element simulation; porosity |
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Title: Liquid co-precipitation for preparing the CoxR1-xCr2O4 (R = Zn, Cd) cobalt green pigment power | ||||
Authors: YUAN Yingming, LIU Wenyan, CHEN Yulin, ZHOU Yingying PP: 866-870 Abstract: By liquid co-precipitation method, this paper researches synthesis and modification of the Cr-Co-based green pigments. Using Cr3+, Cd2+, Zn2+ and other ion-doped means, it researches the effects of doped particle type, number, crystal structure on reflection characteristics of cobalt, chromium green pigment. Adopting reasonable sintering process, the spectral reflectance characteristics of the pigment are close to green plants. Through thermogravimetry-differential thermal analysis (TG-DTA), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM), the doping ions of cobalt, chromium green pigments are characterized. Introduction of divalent cations, increasing the degree of Co2+ 3d level splitling of the electron shell, results in ion hair color Co2+ optical properties change and ultimately afflect the reflective properties of the pigment. Keywords: special function metallic material; green pigment; co-precipitation method; dopant ions; infrared reflection |
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Title: Effect of Ca content on microstructure and properties of Mg-Zn alloy | ||||
Authors: LI Chunnan, QIN Yuan, YANG Sen PP: 859-865 Abstract: In this paper, three kinds of different components of Mg-5.0Zn-xCa (x=0.5, 1.0, 2.0) were fabricated by flux protection method, and microstructure evolution and properties of these alloys were studied. The results show that the as cast Mg-Zn-Ca alloy is mainly composed of α-Mg matrix phase and the second phase Ca2Mg6Zn3 with spherical like or strip like distributed within grains or at grain boundaries. With the increase of Ca content, the amount of secondary phases increases, forming a network structure of continuity and semi continuity along the grain boundaries. The grain is refined with increase of the Ca content, which results in a minor increase of the yield strength of the alloys, however the tensile strength and elongation of the as cast alloy reduces due to the formation of coarse Mg2Ca brittle phase, and corrosion resistance becomes worse as well. Mg-5.0Zn-0.5Ca alloy has better bioactivity than the others, is conducive to calcium and magnesium hydroxy apatite (Ca0.84Mg0.14)10(PO4)6(OH)2 deposition, and the deposition is not easy to fall off, sample surface is integrated. Keywords: metallic material; bioactivity; alloying; Mg-Zn-Ca alloy |
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Title: Synthesis and optoelectronic properties of new polymer acceptors as photovoltaic materials based on perylene tetracarboxylic tetraester | ||||
Authors: XIAO Shengqiang, JIANG Youyu PP: 852-858 Abstract: Perylene tetracarboxylic tetraester as weak acceptor unit was copolymerized with thieno [3,2-b]thiophene and 2,2′-bithiophene respectively to obtain two new donor-acceptor (D-A) type polymeric acceptors P1 and P2 through Stille copolymerization. The thermal stability, optical and electrochemical properties of both polymer acceptors were investigated by thermal gravity analysis (TGA), ultraviolet visible absorption spectra and cyclic voltammograms (CV) measurements. The polymers displayed good solubility and thermal stability. Both polymers displayed narrow optical band gap and higher-lying LUMO energy levels compared to those of fullerene acceptors, as well as well-matched HOMO and LUMO energy levels with those of P3HT as donor material. When exploited as the acceptor combined with the donor of P3HT in all-polymer solar cell with a typical device structure of ITO/PEDOT:PSS/P3HT: Polymer/Ca/Al, P1 and P2 achieved power conversion efficiency of 0.24% and 0.62% respectively. Keywords: semiconductor material; perylene tetracarboxylic tetraester; acceptor; polymer; all-polymer organic solar cell |
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Title: PEG modified WS2 nanosheets for in vivo photothermal therapy | ||||
Authors: CHENG Liang, LIU Jingjing, LIU Zhuang PP: 844-851 Abstract: In this work, a novel photothermal therapy (PTT) agent based on WS2 nanosheets was synthesized for bio-imaging and highly effective in vivo photothermal ablation of tumor PTT. Using the thiol chemistry method, the surface of WS2 nanosheets was coated with polyethylene glycol (PEG), which greatly improved the physiological stability and biocompability of those nanosheets. The PEGylated WS2 nanosheets (WS2-PEG) could serve as a powerful photothermal agent to effectively ablate cancer cells in vitro under near-infrared (NIR) laser irradiation. This work highlights the promise of using light-absorbing transition metal dichalcogenides (TMDC) nanosheets for cancer imaging and therapy. Keywords: inorganic nanomaterial; transition-metal dichalcogenides; toxicity; bio-imaging; photothermal therapy |
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Title: Fabrication of YAG ceramics brackets using slip casting | ||||
Authors: GUAN Yongbing, LU Tiecheng, ZHANG Wei, LU Zhongwen, CHEN Xingtao, WEI Nian, WEI Jianjun, QI Jianqi PP: 840-843 Abstract: High-quality yttrium aluminum garnet (YAG) ceramics brackets were fabricated by vacuum sintering technique and the slip casting using polyacrylic acid (PAA) as dispersant and binder. The powders, suspension and brackets green body were characterized by scanning electron microscope (SEM) and Rheometer. The results showed that the good green bodies could be obtained from slurries with 2% mass fraction of PAA and with 60% (mass fraction) of solid content. High-quality YAG ceramics brackets were fabricated by two-step vacuum sintering technique. It can be expected that the slip casting method with PAA as dispersant and binder is a very promising way for the ceramic brackets forming. Keywords: inorganic nonmetallic material; yttrium aluminum garnet ceramic brackets; slip casting; polyacrylic acid; viscosity; vacuum sintering |
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Title: Effects of sintering temperature on microstructures and properties of directional porous silicon carbide ceramic prepared via physical vapor transport | ||||
Authors: LIU Bobo, YANG Jianfeng PP: 835-839 Abstract: For the directional porous SiC ceramics obtained by the high-temperature recrystallization process, effects of sintering temperature on the microstructure and mechanical properties were investigated. The results showed that the porous SiC ceramics obtained was the approximate isotropic homogeneous porous structure when the sintering temperature was below 2 050℃. When the temperature exceeded 2 150℃, the formation of orientation of porous silicon carbide began, and as the temperature increased, the weight loss increased, and the axial bending strength became higher than the radial value, which was slightly increased followed by decrease. With condition of an Ar atmosphere of 0.3×105-0.5×105 Pa, the sintering temperature of 2 300℃ and soaking time of 2 h, the loosely packed SiC samples were sintered and oriented porous SiC ceramics with axially aligned pore and grain were obtained. The porosity reached to 63.2%, and the ratio of axial and radial strength was 5.34-5.69. Keywords: inorganic nonmetallic material; porous ceramics; SiC; high temperature recrystallization |
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Title: Embedding manganese oxide in silica supported carbon nanomembrane for supercapacitor electrode material | ||||
Authors: HU Aiguo, ZHI Jian, ZHANG Yuxuan, WANG Youfu PP: 829-834 Abstract: Using silica supported carbon nanomembrane (SS-CNM) as a conductive support, electrode material, MnO2@SS-CNM, was prepared by wetness impregnation of manganese nitrate in SS-CNM followed by hydrolysis and high temperature treatment. The formation of MnO2 nanoparticles was confirmed with X-ray diffraction (XRD). It was observed by transmission electron microscopy (TEM) that MnO2 nanopaticle went into the nanopores of SS-CNM and formed a uniform nanostructure. Nitrogen adsorption results showed the presence of size uniformly distributed mesochannels, which was essential for mass transportation. Electrochemical results showed that this electrode material exhibited high specific capacitance of 433 F/g and good cycle stability. Keywords: inorganic nonmetallic material; mesoporous silica; carbon nanomembrane; supercapacitor; composite material |
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Title: Preparation and high electrochemical performance of manganese MnO2/carbon nanocomposites | ||||
Authors: ZHANG Yuxin, ZHU Shijin, DONG Meng PP: 821-828 Abstract: Here, the preparative methodologies of MnO2/C nanocomposites with different morphologies and structures were summarized, such as in-situ growth method, co-precipitation method and electrochemical deposition method. Additionally, electrochemical performances of MnO2/C nanocomposites were detailedly addressed on the basis of diverse carbon templates (i.e., active carbon, carbon spheres, carbon nanotubes, grapheme, and 3D-graphene). At last, based on the status of the electrochemical properties of MnO2/C nanocomposites, their application prospects in near future were proposed. Keywords: inorganic nonmetallic material; MnO2; review; electrochemical properties; supercapacitor |
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Title: Multiscale computational simulation for polymer processing engineering | ||||
Authors: ZHANG Yun, CUI Shubiao, ZHOU Huamin PP: 812-820 Abstract: Microscopic scale, mesoscopic scale, macroscopic scale simulation methods and conjunction technologies among various scales are reviewed. In the microscale, molecular dynamics (MD) and other micro simulation methods are widely used for design of polymer structures and polymer composites, whereas their accuracies, force field models should be improved for polymer processing. Coarse grained molecular simulation methods in mesoscale are very suitable for the evolution simulation of microstructure morphology in polymer processing. However, there are lots of important parameters need to be obtained from microscale simulations. Evolutions of polymer morphology in simple flow field have been simulated by coupling microscope and mesoscope, whereas engineering applications for polymer processing have not been reported. In the macroscale, simulation methods based on the continuum model have perfectly applied for solving flow and heat transfer problems in engineering applications. It is also urgently to develop a three-dimensional model with a high computational efficiency. Technologies and methods connecting macroscope and microscope, mesoscope of polymer processing are still very immature, thus the development of approach connecting multiscale is the key point to quantitative prediction of polymer performance after processing. Keywords: material processing engineering; polymer processing; review; multiscale; computational simulation |
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