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October 30,2010
Volume 3,Issue 20
Pages -
Subject Area:Ceramics,Functional Polymer Materials,Foundational Subject in Materials Science,Amorphous, Nanocrystal Nonmetallic Materials,Composite Materials

Title: First principles study on the electrical structure, optical and phonon properties of ZrB2

Authors: YU Liang, YUE Xinyan, RU Hongqiang, ZHAO Jing, LI Jingyang
PP: 2162-2167
Abstract: Electronic, optical, and lattice dynamic properties of hexagonal ZrB2 crystal have been calculated using first principle based on density functional theory. It is shown that ZrB2 has a metallic character indicated by the band structure and electronic density of states (DOS), and the conduction bands are mainly composed by anti-bond states of B plane and 4d bands of Zr atom. These states are directly related to the optical transitions as shown in absorption spectrum. Population analysis clearly shows that a similar charge transfer mechanism from 3d of Zr to 2p of B occurred as well as in MgB2. In B plane σ bonds are formed by hybirdigation of 2s and 2p orbital. But 2pz responds for delocalized π bond. Lattice dynamical results reveals the vibrational modes which located at B hexagonal plane are made up of high frequency part in phonon spectrum. The prediction of ZrB2 debye temperature should be 59.14 at 0 K according to the results of phonon.
Keywords: ceramics; ZrB2; electrical structure; band structure; optical property; phonon property

Title: Experimental research on mechanical properties of polypropylene fiber

Authors: WANG Huifang, DU Hongxiu, ZHANG Wei
PP: 2158-2161
Abstract: The conducted experiment centers on the mechanical properties of polypropylene fiber and tries to explain influences of different amount of fiber on the high-strength polypropylene concrete, showing on aspects of cube compressive strength, tensile splitting strength, axis compressive strength and elasticity modulus. The experiment shows that: keeping the fundamental ratios of concrete stable, the proper ration of polypropylene fiber is 1.0-1.5 kg/m3.
Keywords: structural engineering; polypropylene fiber; high-strength concrete; mechanical properties

Title: Study of synthesis and performance of SLs-AA superabsorbent polymer

Authors: ZHAO Jianbing, ZOU Lizhaung
PP: 2149-2157
Abstract: SLs-AA superabsorbent polymers were synthesized by solution copolymerization using acrylic acid and sodium ligninsulfonate. The influences of synthesis conditions on reaction and on product properties were investigated and the optimal synthesis conditions were identified. The results were: the mass contents of the crosslinking agent and initiating agent were found to be 0.315 8%-0.411 2% and 5.53%-6.27%, respectively; n(KOH)/n(AA) was found to be 40％-47％; the monomer mass content was found to be 24%-28%; the polymerization temperature was found to be 72-76℃; and the mass content of the sodium ligninsulfonate was found to be 33.54%. The copolymerization mechanism was discussed. The samples were characterized by Fourier transform infrared spectroscopy (FTIR).
Keywords: functional polymer materials; sodium ligninsulfonate; acrylic acid; synthesis condition; performance; superabsorbent polymer

Title: NiCl2 doping polyaniline via mechanical ball milling

Authors: AN Shuzhan, GU Dawei, WU Jiansheng, YAO Yun, SHEN Linjiang
PP: 2142-2148
Abstract: Two groups of conducting ［NiCl2］0.5PANI were prepared by doping polyaniline base with NiCl2 through mechanical ball milling. To investigate the effect of milling rate and milling time on the properties of ［NiCl2］0.5 PANI, the samples were characterized by Fourier transform infra-red (FT-IR), ultraviolet visible (UV-vis), X-ray diffraction (XRD) and conductivity measurement. The experimental results indicated that the doping reaction between NiCl2 and polyaniline base could be induced within 10 min. As increasing milling rate and/or milling time, the conductivity of samples increases firstly, and then decreases, which is similar to the trend of the change of red-shift of characteristic absorption peak of Q, B and C—N stretching vibration resulted by the increase of milling rate and milling time. Higher milling rate and longer milling time may produce the increase of the distance between PANI chains, resulting in the decrease of conductivity and the decrease the change of red-shift for Q, B and C—N stretching vibration absorption.
Keywords: functional polymer materials; mechanical ball milling; NiCl2; polyaniline; doping; conductivity

Title: Synthesis and characterization of MgO nanopowder

Authors: QIN Yinping
PP: 2137-2141
Abstract: This paper developed a precursor pyrolysis method to synthesize MgO nanomaterials. Firstly, the precursors of Mg5(CO3)4(OH)2·4H2O and Mg(OH)2 were synthesized via direct and uniform precipitation routes at 100℃, with anhydrous magnesium sulfate, urea, ammonia, sodium hydroxide as raw materials, respectively. Subsequently，a series of MgO nanopowder materials were prepared by the pyrolysis of the as-obtained precursors Mg5(CO3)4(OH)2·4H2O and Mg(OH)2.
Keywords: materials synthesis and processing; MgO; Mg(OH)2; nanomaterials; precipitation method

Title: Synthesis and characterization of nano-gold particles with specified diameter and shape

Authors: ZHENG Haixia, HUANG Boneng, HU Junman, GONG Yan
PP: 2130-2136
Abstract: Nano-gold particles with different diameters were prepared by chemical reduction, and UV-Vis spectroscopy and transmission electron microscopy（TEM）were used to characterize the morphology and size of the prepared gold nanoparticles. The factors, such as the type of the reducing agent, the amount of the reducing reagent, reagent adding order and reaction temperature, influencing the stability, radius, morphology and dispersion of gold nanoparticles have been studied. The results showed that Au nanoparticles prepared with Na3C6H5O7 as a reductant was within the size of 10-20 nm and prepared with NaBH4 as a reducing agent was within the size of 3-10 nm. The optimum molar ratio of Na3C6H5O7 and HAuCl4 was 1.5∶1. The nano-goad particles prepared after adding HAuCl4 to the hot mixture of Na3C6H5O7 and poly vingl pyrrolidone (PVP) solution were better dispersed, smaller and more uniform than the nano-goad particles prepared after adding Na3C6H5O7 to the hot mixture of HAuCl4 and PVP solution.
Keywords: materials synthesis and processing; preparation of nano-gold particles; sodium citrate reducing agent; sodium borohydride reducing agent; poly vingl pyrrolidone; transmission electron microscopy

Title: Exploration research of PEI non-woven fabrics prepared by electro-spinning

Authors: ZHANG Hui, ZHANG Tianjiao, BAO Jianwen
PP: 2125-2129
Abstract: In this paper, polyetherimide （PEI） non-woven fabrics were prepared by electro spinning in the mixed solvent of chloroform and tetrachloroethane. The micromorphologies of the fabrics were investigated by scanning electron microscope (SEM) and some related software. Besides, from the process, conditions of surroundings and parameters of the machine have been investigated in this paper, which may influence the morphologies of PEI fibers. The results indicated that the ratio of the two solvents and the concentration of the solution are the decisive factors in spinning, and the fibers' micromorphologies could be altered by turning the technological parameters. The diameter of fibers mainly ranged from 0.6 to 2.0 μm.
Keywords: composite material; electro spinning; polyetherimide; non-woven fabrics; solution viscosity

Title: Simplified numerical modeling of 3D piezoelectric composite shells

Authors: ZHONG Yifeng, YU Wenbin
PP: 2117-2124
Abstract: Based on the variational asymptotic method (VAM), an engineering model for piezoelectric composite shell under mechanical and electronic loads has been established, providing a unique method for nonlinear, three-dimensional, one-way coupling piezoelectric problem. The main contents include: derivation of 3D energy expressions based on the decomposition of rotation tensor (DRT); the 3D shell model was rigorously divided into a 2D, nonlinear shell analysis and a linear analysis through the normal direction based on VAM; derivation of approximate energy after dimensionality reduction and reissner-mindlin model conversion; derivation of 3-D field recover relationship. Based on this theory and recover process, the variational asymptotic plate and shell analysis program (VAPAS) was developed. The cylindrical bending example of 4-layer piezoelectric composite shell shows: the three-dimensional field recovered by this theory agrees better with the exact results than that of first-order shear deformation theory (FOSDT) and classic laminated theory (CLT).
Keywords: composite material; piezoelectric composite shells; variational asymptotic method; 3D recover; Reissner-Mindlin model

Title: Effect of CBN embedding methods on the properties of composite electrodepositing coatings

Authors: LI Weiping, WANG Zhiwei, LIU Huicong, ZHU Liqun
PP: 2110-2116
Abstract: Ni cubic boron nitride (CBN) composite coatings were prepared by composite electrodeposition. The composite coatings were characterized by GE-5 digital camera, scanning electron microscope (SEM) and energy dispersive spectormeter (EDS). And the grinding performance was tested. The results indicated that the optimum electrodeposition parameters of CBN embedding process were 20 min, 50~75 A穖-2 through burying sands method in Watt nickel plating system. In this technique, the CBN has more than 47% in volume fraction. What's more, it distributes uniformly and has almost no overlap. The pretreatment of CBN shows a considerable influence on distribution of CBN. Composite coating with CBN pretreated by the H2SO4 and plating bath has better grinding performance and the CBN distributes uniformly in the composite coating.
Keywords: composite electrodepositon; cubic boron nitride; embedding methods; pretreatment; grinding performance

Title: Free volume evolution of Zr55Al10Ni5Cu30 bulk metallic glass with partial crystallization during plastic deformation

Authors: HU Yong, LI Jinfu, LIN Tao, ZHOU Yaohe
PP: 2105-2109
Abstract: Traces of nanocrystals were introduced into Zr55Al10Ni5Cu30 bulk metallic glass by means of isothermal annealing of the glass at 715 K for 30 min. The as-cast and as-annealed samples were rolled up to 95% in thickness reduction at room temperature. The microstructure and thermal behavior of the samples were examined by X-ray diffractometer(XRD), transmission electron microscope(TEM) and differential scanning calorimeter(DSC). It is revealed that the introduction of amorphous/crystalline interfaces in the annealed sample enhances the annihilation rate of free volume during plastic deformation, although the generation rate of free volume is relatively high due to small initial free volume content. As a result, the increase rate of free volume during plastic deformation exhibits no obvious difference between the as-cast and as-annealing samples.
Keywords: bulk metallic glass; crystallization; rolling deformation; free volume

Title: Hot deformation behavior and microstructure evolution of ZK40 magnesium alloy compressed at high strain rates

Authors: WU Yuanzhi, YAN Hongge, CHEN Jihua, ZHU Suqin, LIU Zhiwen, TIAN Jin
PP: 2097-2014
Abstract: The hot compression deformation behavior and microstructure evolution of the homogenized ZK40 magnesium alloy were investigated. The activation energy Q and stress exponent n deduced to be 149.5 kJ/mol and 8.36 by carrying out constitutive analysis. At the lower strain rate (≤1 s-1), dynamic recrystallization (DRX) developed mainly at the grain boundaries. At the higher strain rate (≥10 s-1), DRX developed extensively at the grain boundaries and twins, resulting in a more homogeneous microstructure than the other conditions. The hot deformation characteristics of ZK40 exhibited an abnormal relationship with the strain rate, namely the hot workability increased with the strain rate increasing. However, the DRX grain size was almost the same with the temperature increasing at the strain rate of 10 s-1, while that increased obviously at the strain rate of 20 s-1 and 50 s-1. Therefore, hot deformation at the strain rate of 10 s-1 around and at the temperature range of 250-400℃ was desirable and feasible for the ZK40.
Keywords: alloy material; magnesium alloy; dynamic recrystallization; hot compression; microstructure

Title: Machinability of hypoeutectoid graphitized free cutting steel

Authors: ZHANG Yongjun, HAN Jingtao
PP: 2093-2096
Abstract: In this paper, as the base material of normalized 45 steel, the cutting process of hypoeutectoid graphitized free cutting steel were studied. The results showed that process of tool wear were standard wear curve, the chips were mainly C-shaped accompanied by a small number of spiral chips, and the cutting process was steady, showing that the hypoeutectoid graphite free cutting steel had high machinability and was suitable for batch production on numerical control machine and machining center.
Keywords: metal material; free cutting steel; graphitization; machinability

Title: Investigations on purification of single-walled carbon nanotubes

Authors: YANG Danna, WANG Lin, LI Sai
PP: 2090-2092
Abstract: According to the characteristics of impurities from the prepared single-walled carbon nanotubes (SWNTs) by chemical vapor deposition (CVD), an integrated approach containing liquid phase oxidation, gas phase oxidation, sonication and filtration was applied. And the paper characterized the sample and purified SWNTs by scanning electron microscopy (SEM), thermal gravimetric (TG) analysis and Raman spectroscopy. The results show that the integrated approach is a good purification method and a purity of 95% can be obtained.
Keywords: inorganic nonmetallic materials; single-walled carbon nanotubes; purification; amorphous carbon; metal catalyst particles

Title: Fabrication and properties of Ba(Zr0.63Ce0.27)Y0.1O3-δ/ZnO proton conductors

Authors: GAO Yanying, GUO Ruisong, DENG Yaping
PP: 2085-2089
Abstract: The precursor Ba(Zr0.63Ce0.27)Y0.1O3-δ (BZCY) were synthesized by the conventional solid state reaction route. The sintering behavior and electrical conductivity could be improved by optimization the addition content of ZnO as sintering aids. ZnO was able to form a solid solution with BZCY, resulting in the enhancement of sinterability. As increasing the amount of ZnO, sintered density of the samples increased. When the content amount of substance of ZnO was 2% (BZCY2), the sintered sample had the highest DC conductivity, reaching 9.27×10-3 S/cm at 800℃ in wet H2 atmosphere. The maximum power density was up to 12.4 mW/cm2 at 800℃ with an electrolyte support configuration fuel cell.
Keywords: materials science; BaZrO3; BaCeO3; proton conductivity; sintering aids

Title: Synthesis and characterization of Mn and Co doped ZnO submicrometer crystals by organic thermal decomposition method

Authors: WU Shan, WANG Hao, WANG Hanbin, WANG Xina
PP: 2080-2084
Abstract: This paper reports on optical and magnetic characteristics of the Co and Mn doped ZnO submicrometer crystals synthesized by organic thermal decomposition method. The doped ZnO submicrometer crystals are hexagon cone in shape with size ranging from 100 to 400 nm. X-ray diffraction (XRD), scanning electron microscope (SEM) measurements indicated that the Mn2+ and Co2+ are doped into the ZnO lattice with concentration of around 5％. Photoluminescence of the samples showed suppressed band-gap emission, indicating that the Mn or Co ions in the ZnO lattice increase the non-irradiative recombination processes. Magnetic property measurements revealed that the Mn∶ZnO submicrometer crystals were paramagnetic while the Co∶ZnO exhibited week ferromagnetism at 300 K.
Keywords: inorganic nonmetallic materials; dilute semiconductor; organic thermal decomposition method; ZnO

Title: Photovoltaic application of carbon materials

Authors: CHEN Naigeng, ZHU Hongwei, WANG Kunlin, WEI Jinquan, WU Dehai
PP: 2071-2079
Abstract: Carbon-based photo-voltaic cells (PVCs) have attracted a great deal of interest for both scientific fundamentals and potential applications. In this paper, applications of various carbon materials in PVCs, especially in silicon-based solar cells, organic solar cells and dye-sensitized solar cells, are reviewed. The roles carbon materials played in the PVCs are discussed. Further research on solar cells comprised solely of carbon is prospected.
Keywords: materials processing engineering; carbon materials; reviews; photovoltaic; solar cells

Title: Advances in composite brush plating technology

Authors: ZHOU Shiyong, SHEN Chengjing, WANG Qinqin, HOU Yanfeng, HU Liangliang
PP: 2064-2070
Abstract: In the past decades composite brush plating technology had a tremendous growth, while it was focused on brush plating process and characterization in-depth. However, the research about its formation mechanism has lagged far behind the research about process and performance. Based on extensive research about brush plating at home and abroad, the profile of composite brush plating mechanism and performance is depicted, what's more, the future and development trend of electric brush plating are prospected in the comprehensive work from the research developments of mechanism and process of co-deposition, technology and applicatiom of composite brush plating.
Keywords: surface engineering of materials; composite brush plating; reviews; mechanism; research advance

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