bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Social Presence, Social Exchange and Feedback Features on SNS Continuous Use
Authors: Cheikh-Ammar Mustapha , Barki Henri
Published: March 2016

Social network sites (SNS) are venues for information sharing that provide a variety of communication features capable of stirring emotions, attitudes and beliefs. This paper highlights the role of SNS feedback features and the meanings they communicate to their users, as design elements capable of enhancing the SNS experience. Based on the theories of Social Presence and Social Exchange, the study suggests and empirically validates a research model where Feedback, Perceived Social Presence, Attitude, Enjoyment and Perceived Usefulness are hypothesized to explain intentions to continue to use an SNS. The results of an online survey of 262 Facebook users found that feedback features were central SNS components that influenced perceptions of social presence and enjoyment, which in turn, along with attitude and perceived usefulness, influenced intentions to continue using Facebook, explaining 55% of its variance. The theoretical and practical implications of these results are discussed.
Social Media Engagement Theory
Authors: Di Gangi Paul M. , Wasko Molly M.
Published: March 2016

Business models that rely on social media and user-generated content have shifted from the more traditional business model, where value for the organization is derived from the one-way delivery of products and/or services, to the provision of intangible value based on user engagement. This research builds a model that hypothesizes that the user experiences from social interactions among users, operationalized as personalization, transparency, access to social resources, critical mass of social acquaintances, and risk, as well as with the technical features of the social media platform, operationalized as the completeness, flexibility, integration, and evolvability, influence user engagement and subsequent usage behavior. Using survey responses from 408 social media users, findings suggest that both social and technical factors impact user engagement and ultimately usage with additional direct impacts on usage by perceptions of the critical mass of social acquaintances and risk.
Thickness-Dependent Bipolar Resistive Switching Behaviors of NiOx Films
Authors: Zhu Hua Xing , Huo Jin Qian , Qiu Xiao Yan , Zhang Yi Yang , Wang Rui Xue , Chen Yan , Wong Chi Man , Yau Hei Man , Dai Ji Yan
Published: March 2016

Oxygen-rich polycrystalline NiOx films were prepared by means of magnetron sputtering. Thickness-dependent bipolar resistive switching behaviors revealed that the 20 nm-thick NiOx film presented a clockwise current-voltage loop, while the 60 nm-thick NiOx film achieved an anti-clockwise current-voltage loop. Redox reactions between penetrated Ag ions and drifted oxygen ions in the whole 20 nm-thick NiOx films resulted in the clockwise current-voltage loops. Filamentary conducting paths composed by oxygen vacancies were responsible for the anti-clockwise resistive switching loops of the 60 nm-thick NiOx film.
Preparation and Conductivity of Carbon Fiber Coated with Silver
Authors: Cao Xiao Guo , Liang Chun Lei , Xia Shi Ming
Published: March 2016

Silver-coated carbon fibers successfully fabricated by a modified electroless plating process were characterized by scanning electron microscope (SEM) and X-ray diffraction analysis (XRD). The electroless plating process was modified by replacing the conventional pretreatment and sensitization steps by only using surface hydroxylation step. And the activation and electroless plating steps were merged into one step. The silver layer was successfully coated onto the surface of carbon fibers under the given coating conditions. The effects of AgNO3 solution concentration and reaction temperature on the conductivity of silver-coated carbon fibers were studied in detail. The results indicated that the optimum AgNO3 solution concentration was 0.05 mol/L, and the optimum range of reaction temperature was from 45°C to 65°C.
Synthesis and Characterization of CH3NH3Pb1-xSnxI3 Crystal
Authors: Chen Ju Long , Liang Guang Xing , Fan Ping , Mao Ting Ting , Gu Di
Published: March 2016

The CH3NH3PbI3 light-absorbing layer shows preferably photovoltaic performance. However, comparing with CH3NH3PbI3 film, the CH3NH3SnI3 film show smaller band gap and wider light absorption range, meanwhile, it is non-toxic and environmental friendly solar cell material. In this paper, different proportions of tin (Sn) was doped into CH3NH3PbI3 film, the atomic ratio of lead-tin strictly controlled to form CH3NH3SnI3 from CH3NH3PbI3. The five different proportions of doping CH3NH3Pb1-xSnxI3 perovskite powders were studied. The morphology of powders was observed by scanning electron microscopy (SEM). X-ray diffraction (XRD) and energy dispersive spectrum (EDS) were used to analyze the crystallization and the proportion composition of powders, respectively. The experimental results show that the powder crystal orientation was very obvious at the ratio of lead-tin around 1:1.99 and the atomic ratio close to the ideal stoichiometric ratio of doped atoms.
External Insulation Design Impacts on the Energy Consumption and Greenhouse Gas Emission of Building
Authors: Li Yao , Gong Xian Zheng , Wang Zhi Hong , Li Hao , Fan Miao Miao
Published: March 2016

In order to determine the optimal parameters of the external insulation system and guide the energy saving and greenhouse gas emission reduction of building, a typical student dormitory building in Beijing was chosen as research object. The life cycle thinking and dynamic simulation method were used in the present investigation. The relationship between the expandable polystyrene (EPS) external insulation system design parameters and building energy consumption and greenhouse gas emission in each phase of materials production phase, operation phase and the whole life cycle was studied, systematically . The results show that the consumption of clay brick, concrete and cement mortar account for 98.1% of the total materials consumption, where concrete contributes most to both energy consumption (36.6%) and greenhouse gas emission (35.9%). Regarding the contribution to energy consumption and greenhouse gas emission for building life cycle, materials production phase accounts for 5.6%-18.8% and building operation phase takes up 80.6%-93.4%. With the increase of EPS insulation thickness, the energy consumption and greenhouse gas emission increase linearly in materials production phase, decrease in building operation phase, and have an optimization value in the building life cycle to reach the minimum when the heat transfer coefficient (K) is 0.3W / (m2 • K) equivalent to the EPS insulation thickness is 130mm. Building heating load reduces with the increases of insulation thickness, but the envelope thermal insulation performance has no significant influence on cooling load.
Effect of De-Icing Additives on Aging Properties of Bitumen
Authors: Wang Wei , Yu Jian Ying , Yi Yi , Chen Xiao
Published: March 2016

Effect of three de-icing additives: NaCl, wrapped NaCl (W-NaCl) and Layered double hydroxides (LDHs) on thermo-oxidative and ultraviolet aging properties of bitumen were investigated by thin film oven test (TFOT), pressure aging vessel (PAV) and ultraviolet (UV) radiation test. The experimental result illustrated that compared with bitumen with MF, the softening point and viscosity of bitumen with NaCl and W-NaCl increased and the ductility decreased distinctly after TFOT, PAV and UV aging, indicating that NaCl and W-NaCl accelerated the aging of bitumen. However, for bitumen with LDHs, the softening point and viscosity decreased significantly, the ductility increased after aging, which demonstrated that the anti-aging properties of bitumen were improved effectively by LDHs.
Experimental Study on Corrosion Resistance of GFRP in High Temperature and High Pressure Acid Environment
Authors: Fan Zhou , Fu Jing Wen , Yang Xiao Ying , Hu Xiao Gang
Published: March 2016

In this paper, the corrosion tests of glass fiber reinforced polymer (GFRP) in high temperature and high pressure acid environment were carried out. The surface morphology and glass transition temperature were observed by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and the mechanical property of GFRP was tested. The results indicated that after being exposed to acid corrosion environment, the structure and organization of GFRP changed, and a variety of defects produced on the surface and interior of GFRP, bending strength and tensile strength of GFRP decreased. The surface analysis also proved that there were some etch pits occurred on the GFRP pipes. Furthermore, their barcol hardness became poor.
Synthesis and Characterization Performance of a Novel High Temperature Retarder Applied in Long Cementing Interval
Authors: Lu Ya , Li Ming , Guo Zi Han , Guo Xiao Yang
Published: March 2016

In view of the common polymer retarder of AMPS has poor sedimentation stability for slurry in high temperature, and thickening curve for unusual problems, a new terpolymers retarder PSIH which can solve the problem for the large temperature difference was synthesized by free radical aqueous solution copolymerization using styrene sulfonate (SSS), Itaconic acid (IA) and unsaturated hydroxyl ester monomers X . The structure and thermal stability of the copolymer was characterized with gel permeation chromatography (GPC), infrared spectroscopy (IR), and thermal gravimetric analysis (TG). The application performance of the retarder was assessed. The results demonstrated as follows. 1) The preferred synthesis conditions of the retarder is: the mass ratio of SSS/IA/X=9: 3: 1, temperature=60°C, initiator concentration =2%, the reaction time=5h, pH value was controlled in the neutral bias acidity. 2) Synthetic copolymer is the target product with appropriate molecular weight and has good thermal stability with thermal decomposition temperature of the main chain up to 375°C. 3) Compared with ordinary retarder the PSIH has merits as follows: excellent thermal resistant ability and sedimentation stability in high temperature; the rapid development of compressive strength in low temperature, and a big temperature span (30 °C~150 °C). The thickening time of the slurry with 1.0% PSIH is 245 min at 150°C; the compressive strength of cement with the same dosage can get up to 4.7MPa at 30 °C. In short, PSIH has excellent ability to cope with large temperature difference, providing a strong technical support for complex deep well cementing.
Dissolvable Material and Surface Protection Used in Oil/Gas Field
Authors: Wei Song Bo , Chen Lin , Shi Bai Ru , Pei Xiao Han , Fu Tao , Xie Yi
Published: March 2016

A dissolvable material used in oil/gas field was introduced. The corrosion property of the dissolvable material was characterized by using immersion method and scanning electron microscope. The dissolvable material could quickly react with KCl solution, and the reaction rate improved with the increase of the temperature. In some cases, the downhole tools made by dissolvable materials should not react with well fluid in a short term. Then a protective multilayer coating was fabricated on the material surface. The protective effect of the coating was evaluated with high temperature immersion method. The results indicated that the coating could effectively inhibit the dissolvable material reacting with KCl solution.
In Situ Polymerization Synthesis of Ternary Sulfur/Polypyrrole/Graphene Nanosheet Cathode for Lithium/Sulfur Batteries
Authors: Liu Xin Yi , Li Yue , Zhao Yan , Li Hai Peng , Yin Fu Xing , Zhang Yong Guang
Published: March 2016

A novel sulfur/polypyrrole/graphene nanosheet composite (S/PPy/GNS) was synthesized and investigated as a promising cathode material. This ternary composite was prepared via in situ polymerization of pyrrole monomer with nanosulfur and GNS aqueous suspension followed by heat-treatment. Scanning electronic microscopy observation revealed the formation of a highly porous structure consisting sulfur and polypyrrole coating on the GNS surface. In this composite, GNS works as nanocurrent collector and enhances the conductivity of the composite, and polypyrrole with its high adhesion ability to GNS could act as a binder to connect sulfur and GNS. The resulting S/PPy/GNS composite cathode exhibits high and stable specific discharge capacities of 991 mAh g-1 after 50 cycles at 0.1 C and good rate capability.
Water Absorption Behavior in Poly(Ethylene Terephthalate)-Poly(Ethylene Glycol) Block Copolymer Matrix by Two-Dimensional Correlation Spectroscopy
Authors: Ji Peng , Jiang Zhen Lin , Jin Jin , Chen Xiang Lin , Wang Chao Sheng , Wang Hua Ping
Published: March 2016

The absorption behavior of water in poly (ethylene terephthalate)-poly (ethylene glycol) (PETG) block copolymers was investigated using the time-resolved FTIR-ATR (Fourier Transform Infrared Attenuated Total Reflection) spectra. The data was analyzed by two-dimensional correlation spectra (2D-COS), which provided relevant and complementary information on the absorption mechanism and the molecular interactions formed (H-bonding). It was found that there were two kinds of water molecules, named bound water and free water in absorption process. The delicate relationship between dynamic water absorption behavior and the morphology resulting from phase separation was also discussed. Furthermore, two-dimensional correlation analyses revealed that in the absorption process, water first diffuses into the continuous soft-rich PEG phase and then into the hard-rich PET domains, forming hydrogen bonds with-O-groups prior to that of free volume.
Fabrication of Copolymer PMMA-BMA Oil Absorption Resin
Authors: Chen Lei , Tang Yu Fei , Liu Xu , Zhao Kang
Published: March 2016

PMMA-BMA oil absorption resin was prepared by dispersion polymerization. Oil absorption properties were adjusted by changing the monomer ratio, content of initiator and crosslinking agent. Absorption capacity of porous material, which PMMA-BMA oil absorption resin adhesive in the polyurethane surface, was also investigated. The experimental results show that the best oil absorption ratio of PMMA-BMA copolymer resin was obtained when the MMA/BMA mole ratio was1:1.5, and the initiator and crosslinking agent was 0.4% and 0.35% of the copolymer resin respectively. The porous material was fabricated using the porous polyurethane sponge dipped in the liquid copolymer resin. The porous material resin can be reused since its low oil retention rate, and it can be used as absorption container of oil vapor.
Preparation of Slow-Released Films Based on the Natural Rubber Latex Modified by Cassava Starch
Authors: Zhao Fu Chun , Wu Ai Bin , Zhang Li Yue , Niu Chao Qun , Wang Xiao Hui , Chen Kai Mei , Liao Shuang Quan
Published: March 2016

Nitrogen fertilizer is an important nutrition for the crops. However, the majority of common nitrogen fertilizers have not been absorbed by the plant, which causes great economical loss and environment pollution. In order to solve the above problem, the biodegradable slow-release coating materials for urea was prepared by introducing the active free radical of short chain cassava starch into concentrated natural rubber latex. The effects of the amount of starch, modifier dosage on the water absorption kinetics of natural rubber latex slow-released film, and the mechanical properties, slow-released performance, thermal stability and mildew characteristics in the tropical climate conditions was also examined. The results showed that the swelling rate of natural latex composite film increased with the increment of starch content. However, the water modifier imposed a different effect on the initial swelling rate and the equilibrium-swelling ratio of latex composite film. The preliminary swelling was slow but the time for achieving a basic balance state of the swelling was short. In addition, the thermal degradation process of the natural rubber latex slow-released composite film was divided into two stages. The maximum heat loss temperature of each stage shift toward the each other due to the increasing dosage of water modifier. The biodegradability of the composite film improved but the release rate of urea got faster when the starch content increased.
Preparation and Characterization of Structural Damping Composites Toughened by Polyamide Nonwoven Fabrics
Authors: Ni Nan Nan , Wen Yue Fang , He De Long , Guo Miao Cai , Yi Xiao Su
Published: March 2016

A new kind of structural damping composites was prepared by interleaving polyamide nonwoven fabrics (PNF) between the carbon fiber reinforced epoxy composite laminates. The damping behaviors of the composites made were experimentally investigated using cantilever beam test and dynamic mechanical analysis. The damping ratios of the nonwoven fabrics interleaved composites were compared with the ones of non-interleaved composites. In addition, the interlaminar shear strength and flexible modulus of the composites were also investigated, as well as the composite compression after impact (CAI), Mode I and Mode II interlaminar fracture toughness (GIC and GIIC), in order to evaluate the influence of the polyamide nonwoven fabric layers on the composite mechanical properties. It has been observed that the interleaved polyamide nonwoven fabric layers greatly improved the composite damping loss factors, and the composites containing 7 layers of PNF showed the best damping behavior. Meanwhile, the addition of PNF showed a negligible influence on the composite flexible strength and modulus and interlaminar shear strength. Most importantly, the CAI, GIC and GIIC tests indicated that the composite interlaminar toughness and impact resistance were significantly improved by the interleaved PNF. Finally, the reinforcing mechanism of this kind of composites is discussed.
Multiple Toughening Mechanisms of Laminated Ti-TiBw/Ti Composites Fabricated by Diffusion Welding
Authors: Liu Bao Xi , Geng Lin , Dai Xiang Lin , Yin Fu Xing , Huang Lu Jun
Published: March 2016

Laminated Ti-TiBw/Ti composites behave a moderate loading capacity and high fracture ductility with non-castropic failure stage under three-point bending test. Fracture characteristics of laminated composites reveal many extrinsic toughening behaviors, such as, interfacial delamination, bucking and crack deflection, and the interfacial delamination is attributed to the weak bonding strength. Many strengthening and toughening mechanisms are presented in the TiBw/Ti composite layer, such as de-bonding effects of TiB whiskers, multi-fracture of TiB whiskers, crack trapping effect and crack bridging effect.
Effects of Rare Earth Chlorides on Properties of Al2O3-MgO Castables
Authors: Yuan Wen Jie , Kuang Bi Hui , Zhu Qing You , Deng Cheng Ji , Zhu Hong Xi
Published: March 2016

For the urgent requirements of high performance castables in iron and steel making industry, effects of rare earth chlorides on properties of Al2O3-MgO castables were addressed. The prepared castables were compared in terms of phase compositions, apparent porosity, bulk density, permanent linear change and strength. It was demonstrated that cerium chloride and yttrium chloride exhibited a positive influence on in-situ reactions and volumetric stability of castables. The cation inversion degree of spinel and solid-soluted content of spinel and CaAl12O19 (CA6) were both dependent on the temperature and addition. Cold modulus of rupture for castbles with rare earth chlorides additions calcined at 1450°C was similar to that for referenced castables though the former ones were relatively less at 1250 and 1350°C.
Sb5+ Modified Phase Transition in (Li, Na, K)(Nb1-xSbx)O3 Piezoelectric Ceramics
Authors: Zhao Xiao Kun , Zhang Bo Ping , Zhao Lei , Zhu Li Feng
Published: March 2016

The modified behavior of the phase transition temperatures (TO-T and/or TC) between orthorhombic (O), tetragonal (T) and cubic (C) that caused by doping Sb5+ in (Li0.052Na0.493K0.455)(Nb1-xSbx)O3 (LNKNSx) ceramics was reported in the present investigation. The results show that differing from the insensitive TO-T to the Sb5+ content, TC splits into two peaks TCI and TCII when doping Sb5+. The decreased TCI by raising x may be ascribed to the Sb-rich grains and the settled TCII round 480 °C resulting from the Sb-lack ones. The enhanced piezoelectric coefficient d33 value of 263 pC/N and planar mode electromechanical coupling coefficient kp value of 42.5% at x=0.052 can be attributed to the polymorphic phase boundary (PPB) behavior with an appropriate ratio between T and O phases without any second phase.
Synthesis, Electrical Properties and Chemical Stability of BaCe0.7In0.3-xGdxO3-δ
Authors: Xu Jia Huan , Han Wei , Ding Hui , Chen Wei Jin , Xiang Jun
Published: March 2016

In3+, Gd3+ were selected as substitution elements for Ce4+ in order to increase electrical conductivity and chemical stability of BaCeO3. A modified sol-gel method was used to fabricate BaCe0.7In0.3-xGdxO3-δ (x = 0, 0.1, 0.2, 0.3) nanopowders. XRD results indicated that the diffraction angle moved to lower with increase of the Gd3 + doping concentration, so that the interplanar spacing gradually increased. The impedance spectra analysis showed that conductivity first increased (x = 0~0.2) and then decreased with the Gd3 + doping increase. The total conductivities at 800oC were 3.8 × 10-3 S·cm-1 (x = 0), 8.0 × 10-3 S· cm-1 (x = 0.1), 2.5 × 10-2 S· cm-1 (x = 0.2), 1.36 × 10-2 S ·cm-1 (x = 0.3). Chemical stability test in CO2 show that all samples except for x=0.3 sample calcination at 800oC for 2h under 100% CO2 and x=0, 0.1 samples heating in boiling water for 12h kept main perovskite structure. Therefore, x=0.1 sample show better electrical conductivity and chemical stability.
High Photocatalytic Activity of Covalent Grafting of Phthalocyanines on Crosslinked Electrospun PVA/PAA Nanofibers
Authors: Chang Zhen Jun , Jin Xiao Hui , Zeng Jing , Song Tian You , Zhang Jing
Published: March 2016

Phthalocyanine coated crosslinked electrospun PVA/PAA nanofibers were prepared via electrospinning and esterification reaction. The structure of the as-prepared hybrid nanofibers were characterized by fourier transform infrared spectra, scan electron microscopy and UV–visiable absorption spectroscopy. Their photocatalytic activities were evaluated by the degradation of rhodamine B under visible light, and results showed that it exhibited high activity for degradation of rhodamine B in the presence of hydrogen peroxide. The recycling test was also carried out to prove its reusability in photocatalytic application
Organic/Inorganic Hybrid Materials for Organic Electronic Application
Authors: Liu Jian , Liu Jie , Leng Xing Long , Qu Fu Rong
Published: March 2016

Organic/inorganic stacks were deposited on flexible polycarbonate substrate using inductively coupled plasma chemical vapor deposition (ICP-PECVD) for permeation barrier application. The effects of deposition temperature, RF power, gas flow ratio, deposition pressure on film properties of surface roughness, water vapor transmission rate (WVRT) were investigated. Energy dispersive spectrum (EDS), atomic force microscopy (AFM) and transmission electron microscopy (TEM) were used to characterize the film characteristics of the stack layers. It was found that the surface roughness Ra was as low as is 0.25 nm. The WVRT values of the optimum barriers structures were 10-2g/m2 day (1 pair of stacks) and 4.8 x 10-5g/m2 day (4 pair of stacks). This result indicated that the permeation barrier films prepared by ICP-PECVD could be a promising candidate for flexible electronic applications.
Preparation and Properties of SiC/Phenolic Resin for the Heat of LED
Authors: Wu Cong , Zhao Kang , Tang Yu Fei , Ma Ji Yuan
Published: March 2016

In order to solve the problem that low thermal conductivity of the plastics for the heat of LED, SiC/Phenolic resin for the heat of LED were fabricated combining powder metallurgy. The effects of particles diameters, content and adding nanoparticles on thermal conductivity of the fabricated composites were investigated, the mechanical properties were also characterized. The experimental results showed that the materials were obtained, and the insulation performance of the fabricated SiC/Phenolic resin was higher than the industry standard one, the thermal conductivity reached 4.1W/(m·k)-1. And the bending strength of the fabricated composites was up to 68.11MPa. The problem of low thermal conductivity of the material is expected to be solved. In addition, it is meaningful for improving LED life.
Self-Precipitated Process of Te Nanowire from Zr-Doped Sb2Te3 Film
Authors: Zheng Yong Hui , Cheng Yan , Song Zhi Tang , Yin Wei Jun , Zhu Min , Liu Wei Li , Song San Nian , Feng Song Lin
Published: March 2016

By using Zr6.5(Sb2Te3)93.5 film, Te nanowires with a diameter of 5 to 30 nm were fabricated through annealing process. The results of the bright field TEM images, selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM) demonstrated that the nanowire fitted well with Te hexagonal Te (P3121) structure. The EDS mapping implies that Zr element bonded with Te element and induced the formation of single crystalline Te nanowire during the annealing process.
Synthesis and Characterization of Magnetic Fe3O4/PAAm/LMSH Nanocomposite Hydrogel
Authors: Ma Shu Qiong , Bai Hai Hui , Jin Ran , Zhang Qing Song , Zheng Xiao Nan , Zhang Heng Shui
Published: March 2016

Based on the preparation of polyacrylamide/clays lithium magnesium silicate hydrate (PAAm/LMSH, abbreviated as AP) nanocomposite hydrogel by in-situ free radical polymerization, Fe3O4 nanoparticles were introduced by chemical co-precipitation method, to form magnetic Fe3O4/PAAm/LMSH (abbreviated as MAP) nanocomposite hydrogel. With ESEM, XRD, and TGA technologies, the structures of MAP nanocomposite hydrogel and Fe3O4 nanoparticles formed. Magnetic characteristic of MAP nanocomposite hydrogel was characterized by VSM. The tensile test with Universal Testing Machine was employed for mechanical properties. Furthermore, taking cationic dye Crystal Violet (CV) and anionic dye Methyl Orange (MO) for example, the adsorption properties of MAP nanocomposite hydrogel were analyzed with UV-visible spectrophotometer method. The results show that MAP nanocomposite hydrogel had strong superparamagnetic properties. The introduced Fe3O4 magnetic particles illustrated spinel structure, and nanoparticle size of 8.52 nm. The swelling rate of MAP sample was up to 30.542, showing excellent swelling ability. Compared with AP nanocomposite hydrogel, MAP nanocomposite hydrogel had stronger mechanical strength with the tensile stress of 0.39MPa. Adsorption experiments indicated that MAP nanocomposite hydrogel had favorable adsorption properties on CV with removal rate of 97.6%, 1.27 times that of AP nanocomposite hydrogel. The conclusions confirm the application prospect of MAP nanocomposite hydrogel as dye adsorbent in textile printing and dyeing wastewater treatment.
Effect of Doping Concentrations on Properties of Ga-Ti Co-Doped ZnO (GTZO) Targets
Authors: Cai Xue Xian , Pi Chen Bing , Shang Fu Liang , Yang Hai Peng , Gao Ji Hua , Gao Ling , Yang Hai Tao
Published: March 2016

Ti-Ga co-doped ZnO (GTZO) ceramic targets were prepared by sintering in air at l300°C for 3 h. The morphologies, structure, densification behavior, mechanical and electrical properties of the sintered ceramic targets with different doping concentration were investigated. The optimal doping concentration was obtained. The results indicated that the sintered GTZO targets with total co-doping amount of 2wt% (1wt% Ga2O3 and 1wt% TiO2) had the best properties combination, which was corresponding to an electrical resistivity of 1.56×10-3Ω·cm, a relative density of 99%, a Vickers hardness of 378MPa and a bending strength of 99.4 MPa. The sintered targets were then used to deposit GTZO thin film by pulsed laser deposition. The electrical resistivity of the GTZO thin film achieved 3.78×10-3 Ω·cm, and the optical transmittance was above 85% in the visible light region. This kind of GTZO ceramic has a potential to be used as a high-quality sputtering target to deposit ZnO-based transparent conductive films with good optical and electrical properties.
Antibacterial Activity and Stability of the Electrospun Antibacterial Polymer/Silver Nanoparticle Nanohybrid Mats
Authors: Wu Jin Hui , Wang Run Ze , Hao Li Mei , Yi Ying , Zhao Ming , Wang Zheng , Lin Song
Published: March 2016

In our previous work, silver nanoparticles (AgNPs) with ultrasmall sizes (4.3 ± 0.7 nm) can be in-situ obtained within the poly (vinyl alcohol) (PVA) fibers by mediating the electro-spun conditions. The obtained AgNPs “trapped” within the electro-spun PVA nanofibers were believed to be stable in the dry state, as the abundant PVA molecules could protect the dispersed AgNPs from agglomerating with each other. In this study, based on former study, aging tests about the nanohybrid mats were performed. Through ATR-FTIR spectra analysis, the formation mechanism of AgNPs within the PVA nanofiber by one-step electro-spun was confirmed. Atomic Absorption Spectroscopy analysis of the as-prepared PVA-Ag samples was performed in 14 h and the release of Ag+ was believed to be the main cause of its bactericidal effects. Scanning electron microscopy and transmission electron microscopy were used to characterize the nanofibers with AgNPs. After 4-month storage, the size of AgNPs doped in the PVA nanofiber became twice larger and the content of AgNPs was almost doubled.
Preparation and Biological Properties of Nano-Silk Fibroin/Polyurethane/Silver Nanoparticles Composite Membranes
Authors: Li Jiang Feng , Chen Zhong Min , Luo Qin , Zhang Guang Hui , Wang Fu Ping
Published: March 2016

A series of the blending membranes comprised of the different mass ratio of silk fibroin peptide (SFP) power, silver nanoparticles (NanoAg) and polyurethane (PU) were prepared with mixing the SFP power, silver nitrate and PU, and the silver nitrate was reduced to NanoAg by SFP in this mixing process. UV spectrum was used to detect the nanoAg. The experimental results confirmed the formation of NanoAg. The dissolution of the obtained membranes in simulated body fluid (SBF) were determined, and showed that the membranes had good stability. Their mechanical properties were also determined. The results revealed that the mass ratio of SFP to PU was an important influence factor, and the mass ratio 30/70 (SFP/PU) of the membrane was the optimum. The Antibacterial properties against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa, were examined, the results of which indicated that the membranes containing NanoAg had a good bactericidal effect. The SFP/PU/NanoAg membranes also showed good cell and blood compatibility, and then they have application prospect as an antibacterial materials using for medical catheters.
Cytotoxicity and Hemolytic Properties of Nano-Hydroxyapatite/Polyetheretherketone Biocomposites
Authors: Wang Lin , Song Shen Hua , Wu Zheng Zhi , Duan Li Hong , Wang Chun Bao
Published: March 2016

In order to evaluate the cytocompatibility and hemolytic properties of n-HA/PEEK biocomposites the nanohydroxyapatite/polyetheretherketone (n-HA/PEEK) biocomposites were successfully prepared. The mechanical properties of the biocomposites were proximal to human bone, at the same time, they had the optimal value with the HA volume content of 5%. The PEEK and n-HA/PEEK biocomposites with different HA content extraction medium was prepared with fresh medium. Simple DMEM culture solution was taken as negative control group. The pure PEEK and 5vol.%, 15vol.%, 30vol.% n-HA/PEEK biocomposites were the testing group. The relative proliferation rate of L929 cells was determined on the 1st, 2nd, 3rd and 6th days with CCK-8 assay. The cytotoxicity of n-HA/PEEK biocomposites were evaluated according to ISO 10993-5: 2009. The L929 cells morphology and growth on the 1st, 2nd, 3rd and 6th days were determined under inverted microscope. The hemolysis test in vitro of n-HA/PEEK biocomposites were evaluated through measuring erythrocyte lysis and ferro-hemoglobin freeing degree with indirect contact method basing on ISO 10993-4:2009. The experimental results showed that the growth and morphology of cells in pure PEEK and n-HA/PEEK biocomposites extraction medium had no difference from negative control group. Cytotoxicity test showed that PEEK and n-HA/PEEK biocomposites did not have obvious toxicity on L929 cells, and the cytotoxicity of these extracts was in grade 0-1. Hemolysis test suggested that PEEK and n-HA/PEEK biocomposites did not have obvious hemolysis reaction, and the hemolysis rate of PEEK and n-HA/PEEK biocomposites were 2.37%, 1.71%, 1.05% and 1.32% respectively, which are less than the national standard (5%). It may be concluded that the n-HA/PEEK biocomposites did not have obvious cytotoxicity and hemolysis reaction, which demonstrated that n-HA/PEEK biocomposites had good cytocompatibility.
Effects of Pyrolysis Temperature on the Properties of Phenol-Formaldehyde Resin Based Carbon Molecular Sieve Membrane
Authors: Li Jia Jia , Wei Wei , Lin Qiang , Zhang Jing Yi
Published: March 2016

Carbon molecular sieve membranes were prepared by pyrolysis of novolac type phenol-formaldehyde resin. The influences of pyrolysis temperature on membrane properties were investigated. By raising the pyrolysis temperature from 600 oC to 700 oC, the number of pores and effective pore size increased, thereby making the carbon membrane more productive but less selective. When the pyrolysis temperature from 700 oC to 900 oC, the effective pore size was reduced by sinter effect, thereby the gas permeation rate decreased and selectivity increased. The carbon membranes were characterized by elemental analysis, X-ray diffraction (XRD), and CO2 adsorption. H2, N2, CH4, and O2 were used for pure gas tests to evaluate membrane performance.
Liquid Phase Separation and Dual Glassy Structure Formation of Designed Zr-Ce-Co-Cu Alloys
Authors: Wang Zhong Yuan , He Jie , Yang Bai Jun , Jiang Hong Xiang , Zhao Jiu Zhou , Wang Tong Min , Hao Hong Ri
Published: March 2016

Development of liquid-phase separated bulk metallic glasses is retarded due to difficulties in finding of immiscible systems with high glass-forming ability (GFA) of coexistent liquids. Zr-Ce alloy is a typical liquid immiscible system characterized by a liquid miscibility gap. We added Co and Cu into the Zr-Ce immiscible system and optimized the composition of the designed Zr-Ce-Co-Cu immiscible alloys. The solidification experiments were carried out for the quaternary alloys. The result indicates that the melt separated into ZrCo-rich and CeCu-rich liquids upon cooling through the miscibility gap. By optimizing the relative atomic ratio of Co:Cu, the coexistent ZrCo-rich and CeCu-rich liquids automatically assembled eutectic compositions during the liquid-liquid phase separation (LLPS). Under the condition of fast quenching, the two liquids subsequently undergo liquid-to-glass transition, resulting in the formation of composite structure with two glasses in the samples. We successfully developed phased-separated metallic glasses based on the Zr-Ce-Co-Cu immiscible alloys. This work not only strengthens the understanding in the LLPS but also provides a new strategy on the design of the dual glassy composites.
Microstructure and Corrosion Behavior of Hot Compressed AZ31B Magnesium Alloy Joint
Authors: Chu Ya Jie , Han Xin Chen , Yang Zong Hui , Li Xiao Quan
Published: March 2016

The extruded AZ31B magnesium alloy plates of 4 mm thickness were butt welded using gas tungsten arc welding (GTA) process. The microstructure and corrosion behavior of the hot compressed welds were evaluated by conducting immersion test in NaCl solution at different immersion time and chloride ion concentrations. The specimens were exposed to immersion in order to characterize their corrosion rates. The corrosion morphology and pit morphology observation was carried out by scanning electron microscopy (SEM). The results showed that the corrosion rate of hot compressed magnesium alloy welds decreased with the increase in immersion time and the corrosion rate increased with the increase in chloride ion concentration, and the corrosion morphology was predominantly influenced by the distribution of β-phase.
Compressive Behavior at Ambient Temperature of ZK60-xDy Magnesium Alloys
Authors: Huang Zheng Hua , Qi Wen Jun , Xu Jing
Published: March 2016

Effects of the compressive rate, specimen dimension, specimen orientation and microstructure on the compressive property at ambient temperature of extruded ZK60-xDy alloy rods were investigated. The results show that the specimen dimension, specimen orientation and microstructure except the compressive rate play a significant role on the compressive property. The compressive strength σbc increased significantly by the improving amplitude of 65~110 MPa with increasing the height/diameter ratio h/φ of the cylindrical compressive specimen from 0.5 to 1, however it was not enhanced further as h/φ increased to 2. With increasing the value of h/φ, the yield stage on the compressive curve was strengthened gradually, and meanwhile the compressive macro-fracture changed from the inverted "V" type to pure shear fracture with an angle of 45°. Compared with the specimen whose axial direction was parallel to the transverse direction, σbc was enhanced by the improving amplitude of 60~120 MPa for the specimen whose axial direction was parallel to the extrusion direction. When small amount of Dy (0.31%) was added into ZK60 alloy, σbc was increased from 500 MPa to 540 MPa. However, it slightly decreased to 515 MPa again when the Dy content increased to 4.32%.
Microstructures and Tensile Properties of Mg-6Gd-3Y-1.4Zn-0.4Zr Alloys
Authors: Huang Cen , Liu Chu Ming , Wang Bi Zheng
Published: March 2016

Microstructures and tensile mechanical properties of Mg–6Gd–3Y–1.4Zn–0.4Zr (wt.%) alloy were systematically studied. Three phases were found in the as-cast specimen: α-Mg, Mg5(GdYZn), Mg12(GdY)Zn. The long-period stacking order (LPSO) structure was found in the alloy, which is the phase of Mg12(GdY)Zn. Two LPSO structures with different images were found in the homogenized alloys: the block-shaped ones at grain boundaries and needle-like ones in the inner grains. The homogenized Mg–6Gd–3Y–1.4Zn–0.4Zr (wt.%) alloy was subjected to multidirectional forging (MDF) at 480°C. It was shown that the average grain size decreased to ~5.2μm after 9 passes with the cumulative strain of 2.7. The ageing hardening behavior of as-forged specimens at 200°C has been investigated. Peak hardness was obtained after 26 h, with a value of 110 HV. The ultimate tensile strengths of the as-forged and peak-aged alloys were 398 MPa and 431 MPa, the yield strengths were 351MPa and 398MPa, and the elongations were 11.24% and 8% respectively.
Dynamic Recrystallization Behavior of Mg-Gd-Y-Zr Alloy during Hot Compression
Authors: Yu Shi Lun , Gao Yong Hao , Liu Chu Ming , Xiao Hong Chao
Published: March 2016

Dynamic recrystallization behavior of Mg-8.0Gd-3.0Y-0.5Zr (wt.%) alloy and the critical conditions corresponding to the onset of dynamic recrystallization were investigated using uniaxial compression tests conducted at temperatures ranging from 350 °C to 500 °C and strain rates ranging from 0.001 s-1 to 1 s-1. Results show that increasing temperature and/or decreasing strain rate can enhance the process of dynamic recrystallization of Mg-8.0Gd-3.0Y-0.5Zr alloy and lower the peak stress and corresponding strain. However, decreasing temperature and/or increasing strain rate can promote the occurrence of twin dynamic recrystallization (TDRX) within the original grains at the cost of reducing the total volume fraction of dynamically recrystallized grains in the microstructure. Besides, the critical stress and strain corresponding to the onset of dynamic recrystallization of Mg-8.0Gd-3.0Y-0.5Zr at 400 °C and 0.1 s-1 are 173MPa and 0.13, respectively.
Mechanical Behavior and Microstructure Evolution of Mg-Gd-Y-Zn-Zr Alloy during Multipass Hot Compression Deformation
Authors: Yu Jian Min , Li Xu Bin , Zhang Zhi Min , Wang Qiang , Wu Yao Jin , Wang Jun
Published: March 2016

The multi-pass hot compression deformation behavior of the cast alloy with the composition of Mg-13Gd-4Y-2Zn-0.6Zr, was investigated, and the four-pass compression tests were conducted at the temperatures ranging from 350°C to 500°C and strain rate 0.01 s-1. The experimental results showed that the alloys incurred different degrees of softening by multipass deformation. The microstructure evolution for the deformed alloy was investigated, the influence of the microstructure on the hardness properties of the alloy discussed. The tests reveal that dynamic recrystallization is not the main softening mechanism for this alloy; rather, kink deformation refines the grains to achieve the observed softening effect. The hardness test curve showed that the hardness increased gradually with an increasing number of deformation passes. The improvement of the main mechanical properties related to the strengthening by the grain refinement. In multipass deformation, the misorientation of the kink belt gradually increased,and refined the grains. On the other hand, the grain size of the eutectic phase at the grain boundary decreased with increase of deformation passes. In addition, the mechanical properties were improved by the distribution dispersion of tiny cuboidal particles and acicular-like phases in the matrix.
Effect of Solution Treatment on Corrosion Resistance of the Biodegradable NZ20K Alloy
Authors: Fei Yang , Zhang Xiao Bo , Ba Zhi Xin , Wang Zhang Zhong
Published: March 2016

In order to study the effect of solution temperature on corrosion resistance of Mg alloy for biomedical applications, microstructure and corrosion behavior of Mg-2.25Nd-0.11Zn-0.43Zr (NZ20K) alloy solution treated at different temperatures were investigated by using a scanning electron microscope (SEM) equipped with an electron dispersive spectroscope (EDS), electrochemical and mass loss tests. The results show that the grains grow and precipitations decreases with increasing the solution temperature. The corrosion rate decreases firstly and then increases with increasing solution temperature, and the best corrosion resistance of the NZ20K alloy is obtained at the temperature of 540 °C.
Cellular Automata Simulation on Dynamic Recrystallization of TA16 Alloy during Hot Deformation
Authors: Han Fei , Chen Rong Quan , Yang Chun Hui , Li Xian Min , Wang Ding Chun
Published: March 2016

Dynamic recrystallization is responsible for the properties of the final product of TA16 alloy in hot deformation. In this study, a cellular automata model with dynamic recrystallization (DRX-CA) was developed to simulate and predict the microstructural evolution of TA16 alloy during hot deformation with material constants obtained from hot compressive tests. The proposed model has a capability of tracking the deformation history and microstructural evolution. The numerical simulation results obtained by using the developed DRX-CA model were compared to those experimental data obtained for validation and accurately capture the relations among strain, stress, volume fraction recrystallization, recrystallized grain size and deformation temperature.
Effect of Alpha Phase Characteristics on the High Cycle Fatigue Properties of Ti-6Al-4V Alloy
Authors: Yan Xu , Kou Hong Chao , Han Feng Bo , Tang Bin , Zhang Li Jun , Li Jin Shan
Published: March 2016

In this paper, high cycle fatigue (HCF) properties of Ti-6Al-4V alloys prepared by different forging processes have been investigated. Optical microscopy (OM) and Transmission electron microscopy (TEM) were used to characterize microstructure, and the fatigue fracture micromechanisms were analyzed. Fracture surfaces of specimens were observed by scanning electron microscopy (SEM) to identify the macroscopic fracture mode. It was found that die forging at high temperature would increase the proportion of low angle grain boundary in equiaxed primary α phase and lead to lamella secondary α coarsen with the appearance of dislocation networks, which would make the HCF properties decline. Besides, it showed that the HCF properties increase with increasing the volume fraction of primary α.
Dynamic Compression Properties of Low-Cost Ti-6Al-4V Plates
Authors: Liu Rui , Hui Song Xiao , Ye Wen Jun , Yu Yang , Fu Yan Yan , Song Xiao Yun
Published: March 2016

Ti-6Al-4V ingot with rectangle cross-section was directly manufactured by a single electron beam cold hearth melting (EBCHM) process, in which 65 wt.% recycled titanium scraps was used. The dynamic stress-strain behavior of the low-cost Ti-6Al-4V plates after heat treatment was investigated by Split Hopkinson Pressure Bar system at the strain rates of 2000 s-1~ 3000 s-1. The results showed that the plates with homogeneous microstructure could be obtained after two-heats hot rolled. The dynamic compression properties of low-cost Ti-6Al-4V plates in three different thicknesses were in the same level, which is comparable with that of commercial Ti-6Al-4V plates.
Microstructure and Tensile Properties of Boron-Doped Beta Titanium Alloy
Authors: Chen Rong , Yu Yang , Hui Song Xiao , Ye Wen Jun
Published: March 2016

The microstructural evolution and the mechanical properties of Ti-2Al-9.2Mo-2Fe-0.1B alloy during solution treatment and aging have been investigated. The experimental results showed that the addition of boron resulted in the formation of TiB phase and high level of recrystallization during hot deformation. TiB phase did not moved with the grain boundary migration during solution treatment. On aging, a little of α phase nucleated from the interface of TiB and β phase. The existence of TiB phase could offer the source of cracks during tensile deformation, resulting in the ductility decline of the alloy. In addition, the alloy which aged at 550°C and 600°C for 2h could obtain a good combination of strength and ductility, with 1100~1300MPa of ultimate strength and exceeding 7% of elongation.
Influence of Shot Peening on the Surface Hardness of TC11 Titanium Alloy after High Cycle Fatigue Test
Authors: Liang Yi Long , Zhong Li Qiong , Yan Zhen
Published: March 2016

This paper studied the change of surface hardness after high-cycle fatigue (HCF) test of TC11 alloy with and without Shot Peening (WSP). The results showed that the surface hardness gradient of WSP specimens increased after R=-1 and R=0.1 HCF tests. It was found that the depth and magnitude of surface hardness gradient were related to the stress intensity and cyclic times of HCF, which increased with stress intensity; however, the surface hardness gradient of Shot Peening specimens after HCF maintained the same with that before HCF tests, the values of surface hardness varied slightly after HCF. According to analysis, the surface hardness change of WSP TC11 alloy is related to their surface integrity, which, during the cyclic loading, is due to the higher stress concentration generated on the original machining marks and the cyclic softening of surface layer generated by multi-directional stress.
Microstructure and Mechanical Properties of Powder Metallurgy Ti-22Al-24Nb-0.5Mo Alloys Joints with Electron Beam Welding
Authors: Wu Jie , Xu Lei , Guo Rui Peng , Lu Zheng Guan , Cui Yu You , Yang Rui
Published: March 2016

In this work, a Ti2AlNb based intermetallic alloy with the composition of Ti–22Al–24Nb–0.5Mo (at. %) pre-alloyed powder was firstly produced by gas atomization, and then fully dense powder metallurgy (PM) Ti2AlNb alloy was prepared by a hot isostatic pressing (HIPing) procedure. The HIPed alloy shows uniform microstructure with low number of porosities. In order to broaden the application field of PM Ti2AlNb alloys, electron beam welding (EBW) was proposed to join the intermetallics. The joint quality, microstructure and microhardness of PM Ti2AlNb alloy processed by EBW were characterized, and the results showed that the both base alloy and EBW joints have high metallurgy quality.