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ISSN 1005-0302
CN 21-1315/TG
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      20 September 2014, Volume 30 Issue 9 Previous Issue    Next Issue
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    Orginal Article
    Thermal Annealing and Graphene Modification of Exfoliated Hydrogen Titanate Nanosheets for Enhanced Lithium-ion Intercalation Properties
    Xinning Luan, Ying Wang
    J. Mater. Sci. Technol., 2014, 30 (9): 839-846.  DOI: 10.1016/j.jmst.2014.07.003
    Abstract   HTML   PDF
    Hydrogen titanate has been considered as a promising lithium intercalation material due to its unique layered structure. In the present work, we fabricate 2D graphene/hydrogen titanate hybrid nanosheets for application as anode materials in lithium-ion batteries. H2Ti3O7 nanosheets are synthesized by exfoliation of a layered precursor via interacting bulky tetrabutylammonium (TBA+) cations, followed by ion exchange with Na+ ions and washing with water. The as-prepared hydrogen titanate nanosheets are well-dispersed exhibiting ultra-thin thickness with a lateral size up to a few micrometers. The sample is then annealed at 450, 650 and 850 °C, to optimize its Li+-intercalation property. Heating at 450 °C leads to well-crystallized hydrogen titanate with a trace amount of TiO2. Heating at 650 and 850 °C results in mixed sodium titanates, since some sodium ions in the interlayer structure cannot be washed away and become chemically bonded to [TiO6] octahedra at high temperatures. Electrochemical properties of all the four samples are then evaluated by charged/discharged for 100 electrochemical cycles at 0.01-2.5 V vs. Li+/Li at a specific current of 170 mA g-1. The unannealed hydrogen titanate delivers the highest initial discharge capacity of 130.5 mA h g-1, higher than 124.6 mA h g-1 from hydrogen titanate annealed at 450 °C, as well as 101.3 and 63.8 mA h g-1 from hydrogen titanate annealed at 650 and 850 °C, respectively, due to the high surface area from well-dispersed unannealed nanosheets. However, after 100 electrochemical cycles, well-crystallized hydrogen titanate annealed at 450 °C retain the highest charge capacity of 115.2 mA h g-1, corresponding to a capacity retention of 92.5%, while unannealed hydrogen titanate exhibits a final capacity of 72.1 mA h g-1 and a capacity retention of only 55.2%. To further improve energy density of lithium-ion battery, graphene/hydrogen titanate hybrid nanosheets are fabricated by adding graphene nanosheets into hydrogen titanates. The initial charge capacities of unannealed and annealed hydrogen titanate at 450 °C are significantly increased to 170.7 and 233.9 mA h g-1, respectively. A charge capacity of 101.0 mA h g-1 is retained for unannealed hydrogen titanate with graphene-modification after 100 electrochemical cycles since well-dispersed hydrogen titanate nanosheets can be mixed with 2D graphene more uniformly and thus facilitates diffusion of Li+ ions and retard aggregation of active materials.
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    Surfactant Assisted Dispersion and Adhesion Behavior of Carbon Nanotubes on Cu-Zr and Cu-Zr-Al Amorphous Powders
    Jonathan Nguyen, Haiming Wen, Zhihui Zhang, Frank Yaghmaie, Enrique Lavernia
    J. Mater. Sci. Technol., 2014, 30 (9): 847-853.  DOI: 10.1016/j.jmst.2014.07.002
    Abstract   HTML   PDF
    Carbon nanotubes (CNTs) were dispersed in gas atomized Cu47.5Zr47.5Al5 (CZA) and Cu50Zr50 (CZ) amorphous powders, in an effort to elucidate the mechanisms of adhesion of CNTs onto amorphous metallic powders. CNTs were homogenously dispersed in water using a zwitterionic (ZW) surfactant. Then CZA and CZ powders were submersed in the ZW-CNT suspensions with varying amounts of dwell time in an ultrasonic bath. The ZW-CNT-metal powder suspensions were dried, and CNT-metal composite powders were obtained after decomposition of the surfactant by calcination. Zeta potential measurements on ZW-CNT-metal powder suspensions and scanning electron microscopy investigation into the CNT-metal composite powders both indicated an ideal dwell time, for a specific alloy composition, of metallic powders in ZW-CNT suspension to achieve optimal adhesion of CNTs onto amorphous metallic powder surfaces. The results are rationalized on the basis of hydrolysis of metal ions into suspension creating a net positive charge on the metallic powder surfaces, and the interaction between the charged powder surfaces and the charged hydrophilic head groups of ZW, which has the other end attached to CNTs.
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    Improving the Economic Values of the Recycled Plastics Using Nanotechnology Associated Studies
    W.S. Khan, R. Asmatulu, S. Davuluri, V.K. Dandin
    J. Mater. Sci. Technol., 2014, 30 (9): 854-859.  DOI: 10.1016/j.jmst.2014.07.006
    Abstract   HTML   PDF
    Recycled polystyrene (PS) cups were chopped up and separately incorporated with multiwall carbon nanotubes (MWCNTs) and NiZn ferrite (Ni0.6Zn0.4Fe2O4) nanoparticles prior to electrospinning under different conditions. These nanoscale inclusions were initially dispersed well in dimethylformamide (DMF), and then known amounts of the recycled PS pieces were added to the dispersions prior to 30 min of sonication followed by 4 h of high-speed agitation at 750 r/min. The thermal, dielectric, surface hydrophobic, and magnetic properties of the resultant nanocomposite fibers were determined by thermal comparative, capacitance bridge, vibrating sample magnetometer (VSM), and goniometer techniques, respectively. Test results confirmed that the physical properties of recycled nanofibers were significantly increased as a function of the inclusion concentrations, which may be because of their excellent properties. The consumption of polymeric products as well as their waste materials has dramatically grown worldwide. Although plastic recycling, reprocessing, and reusing rates are growing, the physical properties and economic value of recycled plastics are significantly low. Consequently, this work provides a detailed explanation of how to improve recycled plastics, making them into highly valued new nanoproducts for various industrial applications, including filtration, textile, transportation, construction, and energy.
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    Effects of Annealing Temperature on Cu-Doped ZnO Nanosheets
    Yuliang Liu, Junpeng Wang, Chunhua Xu, Zishu Si, Shensheng Xu, Sanqiang Shi
    J. Mater. Sci. Technol., 2014, 30 (9): 860-866.  DOI: 10.1016/j.jmst.2014.07.014
    Abstract   HTML   PDF
    The synthesis of Cu-doped ZnO nanosheets at room temperature was reported in our previous paper. The effects of annealing temperature on Cu-doped ZnO nanosheets were studied in this paper. Cu-doped ZnO nanosheets were annealed at 200-500 °C in air. The annealed specimens were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that Cu concentration in Cu-doped ZnO nanosheets reduced with increasing annealing temperature. When annealing temperature was lower than Zn melting point (410 °C), the morphologies of the Cu-doped ZnO nanosheets remained nearly the same as that before annealing. However, when the annealing temperature was over Zn melting point, Cu-doped ZnO nanosheets changed to nanowires, wormlike nanosheets or did not change. The change of Cu concentration in Cu-doped ZnO nanosheets is explained by oxidation thermodynamics. A physical model is suggested to explain the morphology changes of Cu-doped ZnO nanosheets, based on the existence of Cu-rich layer beneath Cu-doped ZnO nanosheets.
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    Influence of Sputtered Nanocrystalline Coating on Oxidation and Hot Corrosion of a Nickel-based Superalloy M951
    Xinyue Wang, Li Xin, Fuhui Wang, Shenglong Zhu, Hua Wei, Xiaolan Wang
    J. Mater. Sci. Technol., 2014, 30 (9): 867-877.  DOI: 10.1016/j.jmst.2014.01.001
    Abstract   HTML   PDF
    The isothermal and cyclic oxidation behaviors in air and hot corrosion behaviors in Na2SO4 + 25 wt% K2SO4 salt of M951 cast superalloy and a sputtered nanocrystalline coating of the same material were studied. Scanning electron microscopy, energy dispersive X-ray spectroscope, X-ray diffraction, and transmission electron microscopy were employed to examine the morphologies and phase composition of the M951 alloy and nanocrystalline coating before and after oxidation and hot corrosion. The as-sputtered nanocrystalline layer has a homogeneous γ phase structure of very fine grain size (30-200 nm) with the preferential growth texture of (111) parallel to the interface. Adherent Al2O3 rich oxide scale formed on the cast M951 alloy and its sputtered coating after isothermal oxidation at 900 and 1000 °C. However, when being isothermal oxidized at 1100 °C and cyclic oxidized at 1000 °C, the oxide scale formed on the cast alloy was a mixture of NiO, NiAl2O4, Al2O3 and Nb2O5 and spalled seriously, while that formed on the sputtered coating mainly consisted of Al2O3 and was very adherent. Nanocrystallization promoted rapid formation of Al2O3 scale during the early stage of oxidation and enhanced the adhesion of the oxide scale, thus improved the oxidation resistance of the substrate alloy. Serious corrosion occurred for the cast alloy. The sputtered nanocrystalline coating apparently improved the hot corrosion resistance of the cast alloy in the mixed sulfate by the formation of a continuous Al2O3 and Cr2O3 mixed oxide layer on the surface of the coating, and the pre-oxidation treatment of the coating led to an even better effect.
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    Comparative Study of the Structure and Properties of Ti-O-based Nanowire Films Prepared by Anodization and Chemical Oxidation Methods
    Xinwen Huang, Zongjian Liu
    J. Mater. Sci. Technol., 2014, 30 (9): 878-883.  DOI: 10.1016/j.jmst.2013.10.025
    Abstract   HTML   PDF
    Net-like titanium oxide or H-titanate nanowire films were grown on Ti substrates in 2 mol/L NaOH solutions at 80 °C via anodization method or chemical oxidation followed by proton-exchange. The microstructure, thermal stability and photoelectrochemical property of two types of films were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and photocurrent measurement. It is found that the anodic film mainly consists of a 500-nm-thick nanowire layer whereas the film formed by chemical oxidization is made up of two layers: a nanowire layer (nearly 1 μm in thickness) and an underlying non-nanowire layer (at least 1 μm in thickness). In both two cases, the as-formed nanowires are partly crystallized. Thermal stability investigation reveals that the net-like structure of the anodic nanowire film almost keeps unchanged at a temperature less than 400 °C but is totally destroyed when being calcinated at 600 °C. In contrast, the nanowire layer formed by chemical method is stable even after being calcinated at 600 °C. Our results also show that the uncalcinated or calcinated anodic films are much more photoactive than the corresponding films prepared by chemical oxidization. The difference in photoelectrochemical property of two types of films is discussed based on their microstructures.
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    Twin Growth and Texture Evolution in an Extruded AM30 Magnesium Alloy During Compression
    D. Sarker, J. Friedman, D.L. Chen
    J. Mater. Sci. Technol., 2014, 30 (9): 884-887.  DOI: 10.1016/j.jmst.2014.06.011
    Abstract   HTML   PDF
    The aim of this study was to examine and quantify the growth of extension twins and the associated texture change in an extruded AM30 magnesium alloy during compression along the extrusion direction. Three stages of twin growth with increasing strain were observed due to twin-dislocation interactions, together with increasing texture volume fraction of <0001> and <0001> components. Stage I was characterized by a relatively slow and gradually accelerating growth. A steady-state twin growth was reached in stage II, where the twin width increased linearly with increasing strain. Stage III twin growth became decelerated, exhibiting a plateau-like character.
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    Cytotoxic Effect on Osteosarcoma MG-63 Cells by Degradation of Magnesium
    Mei Li, Ling Ren, LiHua Li, Peng He, GuoBo Lan, Yu Zhang, Ke Yang
    J. Mater. Sci. Technol., 2014, 30 (9): 888-893.  DOI: 10.1016/j.jmst.2014.04.010
    Abstract   HTML   PDF
    Biocompatible and biodegradable magnesium (Mg) based metals have attracted great interest for use in orthopedic implants and devices. Based on our previous study that Mg with and without micro-arc oxidation (MAO) coating showed obvious cytotoxic effect on tumor cells due to the increase of pH value during the degradation of Mg, this study further evaluated the cytotoxic effect of Mg and MAO coated Mg on osteosarcoma (MG-63) cells by analyzing the cell adhesion, morphology and number through observation of scanning electron microscope, as well as live/dead staining, lactate dehydrogenase (LDH) activity and 4, 6-diamidino-2-phenylindole (DAPI) assay. The results indicated that, compared to titanium, Mg could strongly inhibit the cell adherence, morphology and number of MG-63 on the surface of the naked Mg, whereas the MAO coated Mg showed relative weak cytotoxic effect on MG-63 cells, expecting that magnesium based metals with suitable coating can be designed to be applied as tumor prosthesis in the clinical practice.
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    Synthesis, Surface Characterization and Photocatalytic Activity of TiO2 Supported on Almond Shell Activated Carbon
    A. Omri, S.D. Lambert, J. Geens, F. Bennour, M. Benzina
    J. Mater. Sci. Technol., 2014, 30 (9): 894-902.  DOI: 10.1016/j.jmst.2014.04.007
    Abstract   HTML   PDF
    Three types of photocatalysts were synthesized by metal organic chemical vapor deposition and impregnation methods using the almond shell activated carbon as support. These photocatalysts denoted by (TiO2/ASAC (V), TiO2/ASAC (I1) and TiO2/ASAC (I2)) were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS) and nitrogen adsorption-desorption isotherms. SEM observation shows that TiO2 was deposited on activated carbon surface. XRD results confirm that TiO2 existed in a mixture of anatase and rutile phases. The DRS spectra show the characteristic absorption edge of TiO2 at approximate 380 nm corresponding to the optical band gap of 3.26 eV. Besides, FTIR spectrum indicated the presence of (Ti-O) groups. The specific surface area of photocatalysts decreased drastically in comparison with the original activated carbon. The catalysts were very efficient for the photodegradation of total organic carbon (TOC) from industrial phosphoric acid solution under UV irradiation. The kinetics of photocatalytic TOC degradation was found to follow a pseudo-first-order model. The prepared TiO2/ASAC showed high photoactivity for the photodegradation of TOC in the following order: TiO2/ASAC (V) > TiO2/ASAC (I1) > TiO2/ASAC (I2) > ASAC > TiO2 (P25).
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    Effect of Microstructure Scale on Negative Thermal Expansion of Antiperovskite Manganese Nitride
    Zhonghua Sun, Xiaoyan Song
    J. Mater. Sci. Technol., 2014, 30 (9): 903-909.  DOI: 10.1016/j.jmst.2013.12.004
    Abstract   HTML   PDF
    The negative thermal expansion (NTE) properties of the antiperovskite manganese nitrides with micron-scale, submicron-scale and nanometer-scale microstructures, respectively, were investigated using the Mn3Cu0.5Ge0.5N composition as an example. It was discovered that the NTE start temperature, NTE operation temperature range and coefficient of NTE change obviously in a wide range with decreasing the grain size level of the microstructure. The mechanisms for the broadening of the NTE operation temperature range and the decrease in the absolute value of NTE coefficient were proposed based on the grain-size-dependence of the frustrated magnetic interactions and magnetic ordering. The present study indicates that the NTE properties of the antiperovskite manganese nitrides can be tailored by the control of the microstructure scale.
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    Optical Spectra and Gain Properties of Ho3+/Pr3+ Co-doped LiYF4 Crystal
    Jiangtao Peng, Haiping Xia, Peiyuan Wang, Haoyang Hu, Lei Tang, Yuepin Zhang, Haochuan Jiang, Baojiu Chen
    J. Mater. Sci. Technol., 2014, 30 (9): 910-916.  DOI: 10.1016/j.jmst.2013.09.014
    Abstract   HTML   PDF
    The LiYF4 single crystals singly doped Ho3+ and co-doped Ho3+, Pr3+ ions were grown by a modified Bridgman method. The Judd-Ofelt strength parameters (Ω2, Ω4, Ω6) of Ho3+ were calculated according to the absorption spectra and the Judd-Ofelt theory, by which the radiative transition probabilities (A), fluorescence branching ratios (β) and radiative lifetime (τrad) were obtained. The radiative lifetimes of 5I6 and 5I7 levels in Ho3+ (1 mol%):LiYF4 are 10.89 and 20.19 ms, respectively, while 9.77 and 18.50 ms in Ho3+/Pr3+ doped crystals. Hence, the τrad of 5I7 level decreases significantly by introduction of Pr3+ into Ho3+:LiYF4 crystal which is beneficial to the emission of 2.9 μm. The maximum emission cross section of Ho3+:LiYF4 crystal located at 2.05 μm calculated by McCumber theory is 0.51 × 10-20 cm2 which is compared with other crystals. The maximum emission cross section at 2948 nm in Ho3+/Pr3+ co-doped LiYF4 crystal obtained by Fuchtbauer-Ladenburg theory is 0.68 × 10-20 cm2, and is larger than the value of 0.53 × 10-20 cm2 in Ho3+ singly doped LiYF4 crystal. Based on the absorption and emission cross section spectra, the gain cross section spectra were calculated. In the Ho3+ ions singly doped LiYF4 crystal, the gain cross sections for 2.05 μm infrared emission becomes positive once the population inversion level reaches 30%. It means that the pump threshold for obtaining 2.05 μm laser is probably lower which is an advantage for Ho3+-doped LiYF4 2.05 μm infrared lasers. The calculated gain cross section for 2.9 μm mid-infrared emission does not become positive until the population inversion level reaches 40% in Ho3+/Pr3+:LiYF4 crystal, but 50% in Ho3+ singly doped LiYF4 crystal, indicating that a low pumping threshold is achieved for the Ho3+:5I65I7 laser operation with the introduction of Pr3+ ions. It was also demonstrated that Pr3+ ion can deplete rapidly the lower laser Ho3+:5I7 level and has influence on the Ho3+:5I6 level. The Ho3+/Pr3+:LiYF4 crystal may be a potential media for 2.9 μm mid-infrared laser.
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    A Simple Method to Synthesize Multi-branched Carbon Fibers Using Cupric Chloride Aqueous Solution as Catalyst Precursor
    Qiuxiang Wang, Qian Zhang, Liping Chen, Liyan Yu, Lifeng Dong
    J. Mater. Sci. Technol., 2014, 30 (9): 917-921.  DOI: 10.1016/j.jmst.2013.10.019
    Abstract   HTML   PDF
    Carbon fibers with multi-branched structures were synthesized by chemical vapor deposition method using cupric chloride as catalyst precursor and acetylene as carbon source at different reaction temperatures. Effects of water vapor and reaction temperature on the growth mode of carbon fibers were investigated. Experimental results demonstrate that initial reaction conditions and temperature are key factors for the formation of different carbon materials. Carbon fibers with typical multi-branched structures can be obtained at 450 °C when cupric chloride solution was used as catalyst precursor. X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy are used to characterize carbon materials, and the growth mechanisms of multi-branched carbon fibers were discussed.
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    Effect of Structural Parameters of Double Shielded TIG Torch on the Fusion Zone Profile for 0Cr13Ni5Mo Martensitic Stainless Steel
    Dongjie Li, Shanping Lu, Dianzhong Li, Yiyi Li
    J. Mater. Sci. Technol., 2014, 30 (9): 922-927.  DOI: 10.1016/j.jmst.2013.12.012
    Abstract   HTML   PDF
    The effects of double shielded TIG (tungsten inert gas) torch's structural parameters, including the flow rate ratio between the inner and outer layers of gas and the extended length of the electrode (abbreviated as ELE in this work), on the fusion zone profile have been investigated for 0Cr13Ni5Mo martensitic stainless steel. Results show that the double shielded TIG process yields relatively high penetration of the weld pool in a broad range of the structural parameters. ELE over 3 mm is too large and causes adverse reactions on the protection of electrode. The outer gas with relatively high flow rate or the outer layer with high oxygen content is conducive to the oxygen dissolved into the arc, which results in the oxidation of the weld pool surface and the electrode tip. The double shielded TIG welded metal was tested and presented good impact property.
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    Effect of Fe Content on the Interfacial Reliability of SnAgCu/Fe-Ni Solder Joints
    Hao Zhang, Qing-Sheng Zhu, Zhi-Quan Liu, Li Zhang, Hongyan Guo, Chi-Ming Lai
    J. Mater. Sci. Technol., 2014, 30 (9): 928-933.  DOI: 10.1016/j.jmst.2014.06.009
    Abstract   HTML   PDF
    Fe-Ni films with compositions of Fe-75Ni, Fe-50Ni, and Fe-30Ni were used as under bump metallization (UBM) to evaluate the interfacial reliability of SnAgCu/Fe-Ni solder joints through ball shear test, high temperature storage, and temperature cycling. The shear strengths for Fe-75Ni, Fe-50Ni, and Fe-30Ni solder joints after reflow were 42.57, 53.94 and 53.98 MPa, respectively, which were all satisfied the requirement of industrialization (>34.3 MPa). High temperature storage was conducted at 150, 175 and 200 °C. It was found that higher Fe content in Fe-Ni layer had the ability to inhibit the mutual diffusion at interface region below 150 °C, and the growth speed of intermetallic compound (IMC) decreased with increasing Fe concentration. When stored at 200 °C, the IMC thickness reached a limit for all three films after 4 days, and some cracks occurred at the interface between IMC and Fe-Ni layer. The activation energies for the growth of FeSn2 on Fe-30Ni, Fe-50Ni, and Fe-75Ni films were calculated as 246, 185, and 81 kJ/mol, respectively. Temperature cycling tests revealed that SnAgCu/Fe-50Ni solder joint had the lowest failure rate (less than 10%), and had the best interfacial reliability among three compositions.
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    Heat Dissipation Performance of Porous Copper with Elongated Cylindrical Pores
    Hao Du, Dongzhu Lu, Jianzhong Qi, Yanfang Shen, Lisong Yin, Yuan Wang, Zhongguang Zheng, Tianying Xiong
    J. Mater. Sci. Technol., 2014, 30 (9): 934-938.  DOI: 10.1016/j.jmst.2014.03.014
    Abstract   HTML   PDF
    The purpose of this paper is to investigate heat dissipation performance of porous copper with long cylindrical pores fabricated by a unidirectional solidification method. Three samples with porosity of 29.87%, 34.47% and 50.98% were chosen and cut into size of 60 mm (length) × 26 mm (width) × 2 mm (thickness) along the vertical direction of pore axis. Their heat dissipation performance was evaluated by a nonsteady method in air and compared to those of not only bulk copper but also bored coppers with porosity of 30.61% and 32.20%. It is found that the porous copper dissipated heat faster by a forced air convection than that by natural convection from 80 °C to room temperature and both porosity and pore size play an important role in the performance for the porous copper. Furthermore, the heat dissipation rate is higher when the forced air was circulated along the specimens than that perpendicular to the specimens for the porous copper. It is revealed that porous copper with bigger porosity and a proper pore size possesses a higher heat dissipation rate. It is concluded that the porous copper with elongated cylindrical pores has larger heat dissipation performance than both the bulk copper and the bored copper, which is attributed to its higher specific surface area. Application of the porous copper for heat dissipation is promising.
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    Viscoelasticity of Asphalt Modified With Packaging Waste Expended Polystyrene
    Changqing Fang, Linna Jiao, Jingbo Hu, Qian Yu, Dagang Guo, Xing Zhou, Ruien Yu
    J. Mater. Sci. Technol., 2014, 30 (9): 939-943.  DOI: 10.1016/j.jmst.2014.07.016
    Abstract   HTML   PDF
    In view of environmental and economic aspect, asphalt was modified with recycled packaging waste expended polystyrene (WEPS) instead of common polymer. The differential scanning calorimetry (DSC), rotational viscometer and dynamic shear rheology (DSR) were used to analyze and evaluate the viscoelasticity of modified asphalt. Results indicate that the sensitivity of modified asphalt to temperature is decreased while the rut resistance of asphalt is increased. In addition, the viscoelasticity of asphalt is improved after the modification with WEPS. Besides, the modified asphalt has high viscosity at low temperature and low viscosity at high temperature, which is favorable for construction.
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    Microstructure and Strength of Al2O3/Al2O3 Joints Bonded with ZnO-Al2O3-B2O3-SiO2 Glass-Ceramic
    Weiwei Zhu, Jichun Chen, Chuanyong Hao, Jinsong Zhang
    J. Mater. Sci. Technol., 2014, 30 (9): 944-948.  DOI: 10.1016/j.jmst.2014.01.011
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    ZnO-Al2O3-B2O3-SiO2 (ZABS) glass powder was used as interlayer to join alumina ceramics. The effect of joining temperature on the microstructure and strength of joints was investigated. The results showed that the ZABS glass can react with alumina substrate to form a layer of ZnAl2O4 at Al2O3/glass interface. Bending test exhibited that low joining temperature (1150 °C) led to low joint strength due to the formation of pores in the interlayer, originated by high viscosity of the glass. High joining temperature (1250 °C) also resulted in low joint strength, because of large CTE (coefficient of thermal expansion) mismatch between amorphous interlayer and alumina substrate. Therefore, only when the joining temperature was appropriate (1200 °C), defect-free interface and high joint strength can be obtained. The optimum joint strength reached 285 MPa, which was the same as the base material strength.
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ISSN: 1005-0302
CN: 21-1315/TG
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