bluuebunny/crossref_metadata_2025 huggingface dataset:
Microwave Hydrothermal Synthesis of W-Doped CuS Nanoparticle
Authors: Ye Wen Xiang , Zhu Quan Xin , Xiong Wan Qing , Lei Jian , Liao Xue Hong
Published: April 2014

The CuS nanoparticles precursor have been synthesized by microwave irradiation, using copper nitrate and thioacetamide (TAA) as raw materials, dodecyl sodium sulfate as surfactants. After the precursor had being split with n-butyl lithium for 14 days, we synthesized w-doped copper sulfide nanoparticles with microwave hydrothermal method. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectra.
Strain Hardening Behaviour of Hipped and Non-Hipped Castings of Aluminium Alloy 354 Subjected to Two-Step Ageing Treatments
Authors: Gupta Arnav , Eswar Aditya , Babu G. Dinesh , Rao M. Nageswara
Published: April 2014

Cast aluminium alloys are being employed increasingly in the automotive sector due to their light weight and excellent castability. This paper focuses on the strain hardening behaviour of Hipped and non-Hipped components of cast aluminium alloy 354 subjected to two-step ageing, as opposed to the routinely carried out single-step ageing. First step ageing (at 100°C) was carried out for 2 h and 5 h; ageing time at second step (at 170°C) was 1, 2 and 5 h. Mechanical properties and strain hardening behaviour were evaluated for different variants of two-step ageing treatment. Analysis of the results shows that the Hipped components have higher hardening capacity and generally higher strain hardening rate compared to the non-Hipped ones. Some of the two-step ageing treatments give mechanical properties comparable to the conventional T61 treatment, but with significantly higher strain hardening rate.
Feature Recognition of Corrosion Pit for Pre-Corroded AA 2524 and Statistical Analysis
Authors: Li Zhi , Chen Li Jie
Published: April 2014

Corrosion morphology image is one of the most important features for the evaluation of the corrosion damage of materials. By using white light confocal profiler, the corrosion morphologies of AA2524 aluminum alloy specimen are obtained after full immersion to experimental 3.5% salt solution for different time. Through digital image processing, typical corrosion morphology characteristics are extracted, such as the fractal dimension, the depth of pit, the area of pit. By extended 3D box-dimension method, the fractal dimensions of the corrosion surface under immersing time of 24 and 120 hours are determined. The statistical analyses show that the corrosion areas and the characterization parameters ab/2c2 obey Gumma distribution, and the corrosion depth obeys Gumbel, normal, Weibul and log-normal distributions.
Precipitation Behavior of the Second Phase Particles in Grain Oriented Silicon Steel Slabs under Different Reheating Conditions
Authors: Chen Xian Hong , Zhu Chen Yi , Deng Li , Li Guang Qiang
Published: April 2014

The grain oriented silicon steel slabs were reheated at 1323K~1623K with different soaking time in this study. The precipitation behavior of the second phase particles in the steel slabs was investigated by using SEM/EDS combined with other analytic tools. The results show that the main precipitations in samples are MnS and AlN bearing a little of CuxS, and they frequently aggregate with each other by two or three types of precipitations. The quantities of the above three types of precipitations are up to 90% in each sample. These complex precipitations change into AlN bearing a little of CuxS or single AlN after being reheated. The shapes of MnS or AlN havent the common spherical or quadrilateral characteristic outline. There are a few of spherical or irregular shape inclusions such as SiO2, Al2O3, TiO2, CaO, CaS and their complex in the samples. Part of MnS or AlN can also grow around with these particles and then dissolves after being reheated. The sizes of the particles are main in the range of 0.05~0.2μm. There are no inclusions larger than 5.0μm in size observed in the fields of view. The volume density of the precipitations 0.05~0.2μm in size extracted from the quenched samples at 1523K using non aqueous solution electroextraction are 4.04×104/mm3, 4.73×104/mm3, 3.70×104/mm3, 3.33×104/mm3, 3.10×104/mm3and 1.56×104/mm3as the corresponding reheating time is 10min, 30min, 60min, 90min, 120min and 240min at 1523K respectively. The average size of them is 0.108μm. It is more precise to statistics the volume density of the particles in the steel by electrolysis extracting method than that of using metallogrphical analysis. No obvious microstructure variation was observed in the quenched samples after annealing different time. When the reheating temperature reaches 1523K and 1623 K, the grain size grows more easily and the grain boundary gets smoothly. The grain boundary of the samples becomes clear with the increase of the annealing temperature during the same annealing time. The reheating temperature in the present slab is chosen at 1523K and the reheating time is kept for 120 min, which will insure the particles in the slab to dissolve more completely and avoid grain growth abnormally at high temperature.
Low Temperature Sintering of Lead-Free BaTiO3-Based X9R Ceramics with Bi2O3 Dopant and Assisted by LiF-CaF2 Flux Agent
Authors: Zhang Bao Lin , Zhang Bin Bin , Wang Ning Ning , Zhang Jun
Published: April 2014

The sintering temperature of BaTiO3powder was reduced to 950°C due to the Bi2O3-LiF-CaF2addition.Excellent densification was achieved after sintering at 950°C for 10h. The low sintering temperature of newly developed capacitor materials allows a co-firing with pure silver electrodes.The dielectric constant and the temperature stability of the dielectric constant satisfied the X9R standard, which dielectric properties of were ε25°C1115, ΔC/C25°C±12% (55~200°C), tanδ1.5% (25°C).
Structural Deformation and Stress Analysis of Aircraft Wing by Finite Element Method
Authors: Rabbey M. Fazlay , Rumi Anik Mahmood , Nuri Farhan Hasan , Monerujjaman Hafez M. , Hassan M. Mehedi
Published: April 2014

Wing of an aircraft is lift producing component. It makes aircraft airborne by generating lift>weight. The wing must take the full aircraft weight during flying. So, it is very sophisticated task for designing a wing by keeping consideration of every design parameters simultaneously. This paper contains analysis of structural properties of wing by using finite element method. For well-organized design all the variables must be considered from the beginning of the design phase. The design phases for aircraft are: conceptual, preliminary and detail design. Until the preliminary design phase the aircraft structure is not considered. During these phases the material of the wing should be selected in such a way so that it can perform efficiently with less unexpected phenomena (drag) for which responsible properties are displacement, stress etc. Currently the most focusing area for the aero-elastic investigation is to design wing with good aerodynamic shape which will associated with less dragging structural behavior. It helps to reduce SFC (Specific Fuel Consumption) and so the cost. The analysis on that has done through Computational means as well as simulation technique to develop knowledge about the variation of aircraft wing structural properties.
Rechargeable Alkali and Alkaline Earth Metal-Air Batteries – Potential and Challenges
Authors: Cheng Hua , Scott Keith
Published: April 2014

In order to resolve environmental and sustainable energy concerns, significant efforts are required to find ways to minimise the use of fossil fuels and to shift to renewable energy resources such as solar, wind, and geothermal power generation. The key to success lies in developing reliable large scale high power energy storage devices. The lithiumair battery has been suggested as one candidate because of its exceptionally high energy storage capacity. Non-aqueous metal-air batteries utilising alkali and alkaline earth metal anodes also offer great gains in energy density over the state-of-the-art Li-ion battery. They are also unique power sources because the cathode active material (oxygen) does not have to be stored in the battery but can be accessed from the atmosphere. Moreover, alkali and alkaline earth elements are much more abundant than lithium and therefore would offer a more sustainable energy storage solution for even beyond the long-term. This work is to enable the uptake of this technology by fully analysing its principle and by exploring the application of nanostructured catalytic cathode materials. The potential of alkali and alkaline earth metal-air batteries will be demonstrated by their electrochemical cycling performance and will be compared with the lithium-air battery. The challenging issues will be discussed according to experimental observations.
A Theoretical Formula for the Validity Limits of the Dipole Approximation for a Dielectric Mixture
Authors: Yang Chang He , Cao Ding Long , Guo Lin Song
Published: April 2014

A newly criterion for the validity limits of the dipole approximation for a dielectric mixture was presented, based on the comparison between the dipole approximation and the numerical solutions by the finite-element method (FEM). In terms of this criterion and the dipole-enhanced model, a simple theoretical formula for the validity limits was derived. This formula includes three variables: the dielectric mismatch, the volume fraction of particles and the precision. Its calculated results have a good agreement with the limits determined by the empirical method in the range of our interest, which indicates the theoretical formula is creditable. Using this formula, we can approximate the precision of the dipole approximation for an arbitrary dielectric mixture. And we found that the dipole approximation is acceptable with the precision equal to 30% when the dielectric mismatch is less than 2.3 (εi/ εe2.3) for the almost touching spheres.
Simulation of Ion Beam Irradiation Effects in Perovskite Oxide Memristors
Authors: Knežević Ivan , Obrenović Marija , Rajović Zoran , Iričanin Bratislav , Osmokrović Predrag
Published: April 2014

Radiation effects of ion beams in perovskite oxide memristors are analyzedand linked to absorbed dose values, calculated from simulations of ion transport. Several ion species were used in simulations, chosen to represent certain commonly encountered radiation environments. Results indicate that considerable formation of oxygen ion - oxygen vacancy pairs, as well as advent of displaced rare earth and alkaline atoms, is to be expected. Oxygen vacancies can lead to a decrease or increase of active layer resistance, depending on applied voltage polarity. The loss of vacancies from the device is bound to impair the performance of the memristor. Calculated absorbed dose values in the memristor for various incident ion beams are typically on the order of several kGy.
Life Cycle Assessment of Rock Wool Board and EPS Board
Authors: Li Zhu , Gong Xian Zheng , Wang Zhi Hong , Liu Yu , Ma Li Ping , Wang Shu Ping , Guo Jie
Published: April 2014

Although outer wall thermal insulation technology is an effective measure for building energy-saving, the production of thermal insulation materials causes serious impacts on environment. In the present investigation the resource, energy consumption and environmental emission of the two kinds of thermal insulation materials were analyzed, from the acquisition of raw materials to production process based on Life Cycle Assessment (LCA). The result show that life cycle energy consumption of rock wool board is 415MJ per functional unit, proximately twice of EPS board’s (220MJ). Overall, environmental impact indicators caused by rock wool board is more serious than EPS.
Life Cycle Assessment of Heavy-Duty Truck for Highway Transport in China
Authors: Li Chen , Cui Su Ping , Gong Xian Zheng , Meng Xian Ce , Sun Bo Xue , Liu Yu
Published: April 2014

The detailed life cycle assessment of heavy-duty truck for highway transport in China is conducted by Centre of National Material Life Cycle Assessment (CNMLCA). The input of energy and output of pollutants emissions are documented as the life cycle inventory (LCI). The life cycle impact assessment (LCIA) results calculated with the CML method show that the hotspot of environmental impacts from transport in China. The environmental benefits from implementations of European emissions standards in China for transport are also analyzed. The analysis shows that the acidification potential (AP) makes the most huge contribution to total environmental impact, up to 33.7%. As the second hotsopt, global warming potential (GWP) takes up 26.83% of total environmental impact. Photochemical oxidant formation potential (POCP) takes up 23.42% of total environmental impact, which is more or less the same comparing with the result of GWP. Eutrophication potential (EP) takes up 15.05% of total environmental impact. The last but not the least environmental impact category - human toxicity potential (HTP), only takes up 0.95% of total environmental impact. If the heavy metal and dioxin emissions are also considered, maybe the results will be changed and the HTP will take more in the whole environmental impact. It can be concluded that if we pay more attention on SO2emissions especially NOx emissions reduction, the acidification and photochemical smog would be relieved a lot and the total environmental impact can be decreased a lot. More punishment on overload may be a good choice to reduce environmental load of heavy truck of highway transport in China.
Selection of Building External Windows in Different Climatic Zones Based on LCA
Authors: Zhao Chun Zhi , Jiang Quan , Zhao Ping , Ma Li Ping
Published: April 2014

The area of building external windows is about 30% of the total area in building envelope, but the energy loss of the external windows accounts for over 50% of the building energy. Building external windows is the weakest parts of insulation performance in building envelope. Based on the method of life cycle assessment (LCA), this article deeply surveys and analyzes the resource consumption, energy consumption and pollutant emissions of bridge-cut-off aluminum alloy windows, unplasticized polyvinyl chloride (PVC-U) windows and aluminum-wood composite windows. This article calculates five main environmental impacts of functional unit (per m2) for the three products including the non-renewable resource consumption, energy consumption, greenhouse effect, acidification and eutrophication. The results show that to meet local design standard for energy efficiency and to achieve the same energy-saving effect, the environmental impacts of different climate zones in external windows from low to high are in the following order: unplasticized polyvinyl chloride (PVC-U) windows with 70 series (4 or 5 cavity), aluminum-wood composite windows with 68 series, un-plasticized polyvinyl chloride (PVC-U) windows with 60 series (3 cavity), bridge-cut-off aluminum alloy windows (55-58 series, the height of PA66 from 14.8mm to16.8mm), and bridge-cut-off aluminum alloy windows (65-70 series, the height of PA66 from 22mm to 35mm). This research provides domestic basic data for building external windows and green building.
Revisit of Thermoelectric Efficiency and Figure-of-Merit
Authors: Wang Chun Lei , Zhu Yuan Hu , Su Wen Bin , Liu Jian , Li Ji Chao
Published: April 2014

Thermoelectric efficiency power generation represented based on the transportation equations obtained under different physical boundary conditions in the present investigation. The figure-of-merit and power factor derived from optimizing thermoelectric efficiency and maximizing power output. It is interesting to note that the maximum output power reached when the load resistance was the thermoelectric adiabatic resistance, while the optimized thermoelectric efficiency responded the isothermal resistance. The possible approach to characterizing these thermoelectric parameters proposed in the present investigation.
Effects of Oxygen-Reduction on Thermoelectric Properties of Sr0.61Ba0.39Nb2O6 Ceramics
Authors: Li Yi , Liu Jian , Wang Chun Lei , Su Wen Bin , Zhu Yuan Hu , Li Ji Chao , Mei Liang Mo
Published: April 2014

The thermoelectric properties of Sr0.61Ba0.39Nb2O6 ceramics, reduced in various conditions, were investigated in the temperature range from 323K to 1073K. Both the electrical resistivity and the absolute Seebeck coefficient decreased with the deepening degree of oxygen-reduction. However, the decrease of the electrical resistivity had a major influence on the thermoelectric power factor. Therefore, the more heavily reduced sample can gain the higher value of thermoelectric power factor. It has been observed that the thermal conductivity increased with the deepening degree of oxygen-reduction, which indicates that the scattering of the oxygen vacancies produced by reduction does not play a dominant role in the thermal conduction. In spite of the increase of the thermal conductivity, the oxygen-reduction still promoted the thermoelectric figure of merit via the increase of the thermoelectric power factor. And the most heavily reduced Sr0.61Ba0.39Nb2O6 ceramic has the highest thermoelectric figure of merit (~0.18 at 1073 K) among all the samples.
Effects of Mechanical Treatment and Pre-Deformation on Shape Recovery Stress of Ti50Ni47Fe3 Shape Memory Alloy
Authors: Zhang Yu , Liu Fu Shun
Published: April 2014

Effects of mechanical treatment, pre-strain and pre-deformation temperature on shape recovery stress of Ti50Ni47Fe3 shape memory alloys were investigated. Mechanical treatment, consisting of hot-rolling and hot-forging, improved σrmax σrmax (maximum recovery stress), dσr/dT (rate of recovery stress with temperature) and Ts (the temperature at which recovery stress rises sharply). Martensitic transformation and reverse transformation temperatures also increased with increasing the hot-rolling deformation. σrmax and dσr/dT increased with increasing pre-strain at first and then decreased with further increasing of pre-strain, and the maximum values of σrmaxand dσr/dT were obtained at a pre-strain of 10%. On the other hand, σrmaxand dσr/dT decreased with increasing pre-deformation temperature. Upon a hot-rolling of 88% area reduction and pre-deformation of 10% at-150°C, the Ti50Ni47Fe3 alloy exhibited excellent recovery stress property with the σrmax of 391MPa in combination with dσr/dT of 5.09.
Effect of C12-14 Alcohols on the Thermomechanical Properties of Epoxy Shape-Memory Polymer
Authors: Zhao Li Min , Feng Xue , Mi Xu Jun , Li Yan Feng , Xie Hao Feng , Yin Xiang Qian
Published: April 2014

A critical parameter for a shape memory polymer (SMP) lies in its shape memory transition temperature. For an amorphous SMP polymer, it is highly desirable to develop methods to tailor its Tg, which corresponds to its shape memory transition temperature. Starting with an amine cured aromatic epoxy system, epoxy polymers were synthesized by introducing flexible aliphatic alcohol. The thermal and thermomechanical properties of these epoxy polymers were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). All the crosslinked epoxy polymers with Tg’s above room temperature were found to possess shape memory properties.
Topology Option of Bias Magnetic Field for Magnetostrictive Actuator
Authors: Xia Qing , Zhang Tian Li , Yu Jin An , Jiang Cheng Bao
Published: April 2014

In the design of giant magnetostrictive material (GMM) actuator, the bias magnetic field is a vital part. For the use of GMM rod in the magnetostrictive actuator, there are two typical topology structures, in-line structure and coaxial structure. Although these structures have been used in the design of magnetostrictive actuator, little work has been done to compare the general features for concrete application conditions. In this paper, we use finite element analysis (FEA) as the main tool to analyze and compare these structures and come to a conclusion that, as to a diameter-limited actuator, when the length to diameter ratio of the rod is less than 5, coaxial actuator can provide more uniform magnetic field and less moving parts; when the length to diameter ratio of rod is 5, the field inhomogeneity is nearly equal, and coaxial actuator uses less moving parts and in-line actuator cost less permanent magnet (PM); when the length to diameter ratio of rod is more than 5, in-line actuator can provide more uniform magnetic field and use less PM.
Fabrication of Cu2ZnSnS4 Thin Films by Sputtering from a Single Quaternary Chalcogenide Compound
Authors: Wang Jian Sheng , Li Song , Cai Jia Jia , Ren Yu Ping , Qin Gao Wu
Published: April 2014

Cu2ZnSnS4thin films were fabricated by one-step RF magnetron sputtering of a single quaternary Cu2ZnSnS4(CZTS) chalcogenide target on Mo/soda lime glass substrate, followed by post sulfurization using S vapor obtained from elemental S powders. The films were thermally annealed in Ar atmosphere to improve the crytallinity. The sulfurization temperature was fixed at 550°C. Both as-deposited and post-sulfured samples are close to the stoichiometric composition, meanwhile without any second phase was detected by XRD. As-deposited film has a compact columnar grain characteristic. Although crystallinity was improved with increasing annealing time, this characteristic disappeared after post-sulfured.
Photovoltaic Effects of Bismuth Ferrite and Nd-Doped Barium Titanate Thin Films Prepared by Sol-Gel Method
Authors: Fu Chun Lin , Cai Wei , Lin Ze Bin , Jiang Wei Hai
Published: April 2014

Ferroelectric is a great potential material as new solar cells, light driver and optical sensor because of its anomalous photovoltaic effect. Bismuth ferrite and Nd-doped barium titanate thin films were prepared via sol–gel spin-coating method in the present study. The experimental results show that substitution of Nd3+ ions for Ba2+ on A sites leads to the decrease of band gap, and the short circuit photocurrent density, open circuit photovoltage and power conversion efficiency of Nd-doped barium titanate thin films begin to increase and reach the maximum and then decrease as Nd content increases. It has been found that the band gap of bismuth ferrite thin films annealed at 550–650oC was between 2.306 eV and 2.453 eV. The short circuit photocurrent density decreased with the rise of annealing temperature, and the open circuit photovoltage and the power conversion efficiency of bismuth ferrite thin films annealed at 550oC were higher than the thin films annealed at higher temperature.
Influence of Particle Size Distribution on the Consistency of High Permeability MnZn Ferrite
Authors: Chen Cheng Hai , Li Xiao Long , Zhang Ling , Ying Yao , Jiang Li Qiang , Che Sheng Lei
Published: April 2014

High-permeability MnZn ferrite cores were sintered under various sintering temperatures and atmospheres by using powders of different particle size distributions. It has been found that electromagnetic performance of cores sintered from powders with finer particle size and narrower size distribution varies less upon the change of sintering temperature and atmosphere. This suggests that the permeability consistency of MnZn ferrite can be improved by using fine powder with better uniformity in mass production.
Synthesis of Pure Dicalcium Silicate Powder by the Pechini Method and Characterization of Hydrated Cement
Authors: Tan Yan Ni , Liu Yong , Qing Zhang , Birdi Gurpreet , Grover Liam M.
Published: April 2014

Calcium silicate (CS) is a main component of Portland cement and is responsible for the strength development. Recent research has shown that dicalcium silicate cement (CSC) is bioactive and is a potential candidate for bone replacement. Traditionally, dicalcium silicate powder is synthesized by a solid state reaction or a sol-gel method. The solid-state reaction, however, usually needs a higher temperature and a longer calcination time. Furthermore, the dicalcium silicate powder made by the sol-gel method is not pure, and contains a significant quantity of CaO which is harmful to the strength and biological properties of the CSC. The Pechini technique is an alternative, low temperature polymeric precursor route for synthesis of high purity powders. In this study, purer CS powder was synthesized via the Pechini method by calcination at 800°C for 3h. DSC-TGA, XRD, SEM were used for characterization of CS powder and the hydrated cement. The DSC-TGA curves showed that the main exothermic peak was at 479°C and the total mass loss was 79.2%. The XRD patterns of CSC after hydration for 7, 14, and 35 days illustrated that dicalcium silicate hydrate (Ca1.5SiO3.5·xH2O, C-S-H) was formed in the hardened CS paste. The XRD peaks on the diffraction pattern of the C-S-H of the day 35 sample were of greater intensity than those at day 7 and day 14. This demonstrates that the hydration speed was slow and complete hydration could take more than one month. Flake-like crystals were observed on scanning electron micrographs following hardening. The degradation study result showed that there was no mass loss of CSC after the samples were soaked into phosphate buffered saline (PBS) for 40 days. The silicon assay revealed that orthosilicic acid could be released from CSC after the samples were soaked in simulated body fluid (SBF). Silicon is known to be critical to skeletal mineralization. The existence of silicon may stimulate the proliferation of bone and activate cells to produce bone. Investigation of cell attachment confirmed that the MC-3T3 cells attached well to the surfaces of CSC after seeding.
Size Effect on the Transformation from Graphite to Nanodiamonds
Authors: Tian Fei , Yang Hong , Zhao Yong Guang , Cao Hong Mei
Published: April 2014

The synthesis of nanodiamonds by pulsed-laser ablation in liquid (PLAL) is an attractive research field in developing well-dispersed fluorescent nanodiamonds for bioimaging and life science. However, nanodiamonds are quite different from their widely pursued carbon allotropes both in synthesis conditions and physical properties. It is a great challenge to synthesize metastable phase nanodiamonds that prefer high temperature and high pressure. Despite the progress in the synthesis of nanodiamond by pulsed-laser ablation of graphite target using different laser power densities under room conditions, the transformation from graphite to nanodiamonds are not yet well explained. In order to have a better understanding to the formation of metastable nanodiamonds upon PLAL, the formation of nanodiamond has been elucidated from both the aspects of thermodynamics and kinetics. Due to low laser intensity and long wavelength, synthesis of nanodiamonds is the result of high cooling velocity of high-pressure and high-temperature carbon vapor condensation formed under laser vaporization of graphite particles. When diamond nuclei grow into the right size, they cannot increase and the graphite nucleation begins to form and grow on the diamond at given conditions due to long pulse width for ms-pulsed laser. In fact, the diamond particles enwrapped several layers of graphite have obtained. Moreover, the reasons related 3~6nm diamonds prepared by this new process and having narrow size distribution are also discussed.
Improvements of Superconducting Properties on Bi-2212 Bulks by Element Doping
Authors: Zhang Sheng Nan , Li Cheng Shan , Hao Qing Bin , Lu Tian Ni , Zhang Ping Xiang
Published: April 2014

Bi-2212 bulks have been fabricated by spark plasma sintering technique with the Bi-2212 precursor powders synthesized by co-precipitation process. The Al2O3dopants were added into the precursor powders during the sintering process. The lattice parameters of Bi-2212 increased with Al content, suggesting that Al3+ions entering into the lattice as interstitial ions due to the small ion radii. The carrier concentration has been calculated with measured room temperature thermopower values. The change of carrier concentration can be attributed to the changes of both Al and oxygen contents in the lattice. Therefore, by Al doping the samples have been tuned into optimal doping region with maximum critical temperature of 86K. The appearance of Al interstitial ions in the lattice caused certain amount of point defects, which acted as pinning centers. Therefore the flux pinning properties have been enhanced in the bulks, and obvious improvements of critical current density for over 55% have been obtained at 4.2K self-field.
Preparation of Bionic Structure TiO2 Using Napkin as Template and its Photocatalytic Performance
Authors: Chen Feng , Liu Cheng Bao , Qian Jun Chao , Wu Zheng Ying , Chen Zhi Gang
Published: April 2014

Biomophic titanium oxide with nanocrystalline was successfully synthesized using napkin template, which everybody uses. Unique biomorphic microstructures were characterized by field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) and nitrogen absorption-desorption techniques. TiO2 material was characterized by repetitious networks consisting of the fibers with diameter of 1-6μm. The results showed that the products were composed by polycrystalline TiO2 nanoparticles with diameter of ca. 5-8 nm and the high specific surface area (81.0 m2·g-1) of sample,which were believed to result from the X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and the Brunauer-Emmett-Teller (BET) method. While the concentration of acid black solution was 20 mg/L, catalyst amount 0.1 g/L, the reaction had a higher photocatalytic performance following irradiation with a visible light by xenon lamp, the decoloring rate can reach over 100% after 250 min.
Forming of Seat Bidet by AZ31 Magnesium Alloy through Stamping Process
Authors: Wang Li Fei , Li Hong Cheng , Huang Guang Sheng , Zhang Hua , Jiang Shan , Liu Bin , Pan Fu Sheng
Published: April 2014

In this paper, the forming of a seat bidet at 150°Cand 200°C by AZ31 magnesium alloy through the stamping process was conducted. The microstructure and the press technology were investigated. The results show that the lubrication and temperature have an important impact on the stamping forming. The seat bidet can be forming successfully by warm stamping. While the defect and fracture behavior mainly occurs at the corner of the seat bidet and the slant groove in the center.
Effects of Different Sr Additions on As Cast Microstructure and Tensile Properties of AS31 Alloy
Authors: Zhou Ji Xue , Zhao Dong Qing , Wang Jin Wei , Tang Shou Qiu , Li Wei Hong
Published: April 2014

Effects of different Sr additions (0.1%-1%Sr, mass fraction) on as-cast microstructure and tensile properties both at ambient temperature and elevated temperature of AS31 magnesium alloy were studied. The experimental results show that the addition of Sr could refine the grain size obviously and modify the eutectic Mg2Si from Chinese script shape to polyhedral shape or fine fibers shape. The addition of Sr to AS31 alloy improved the tensile strength at ambient temperature, and the ultimate strength at 150°C first decrease and then increase with the Sr addition increase from 0.1% to 1%Sr.
Calculation of Aluminum Equivalent Based on Thermo-Calc Software in Ti-Al-Nb Ternary System
Authors: Yang Hui Min , Luo Liang Shun , Song Mei Hui , Qi Hai Qun , Wang Chun Yan , Yang Chuang
Published: April 2014

Ti-Al-Nb ternary phase diagrams were calculated by Thermo-Calc software. The analysis of the calculated vertical sections of Ti-Al-Nb phase diagram indicated that when Nb content is fixed at 5at.% and Al content is lower than 52.3at.%, the primary phase would be β phase during solidification. With 10 at.%Nb and Al content lower than 55.8at.%, or with 15 at.%Nb and Al content lower than 56.9at.%, the primary phase would be β phase. The vertical sections of Ti-Al-Nb ternary phase diagram were further simplified into pseudo-Ti-Al binary phase diagram. According to the pseudo-Ti-Al diagram, the expression of the aluminum equivalent was obtained in Ti-Al-5Nb ternary alloys.
Forming Parameter Design and Thickness Uniformity Control of Short Radius Elbow Made by Expanding Diameter and Pushing Bend
Authors: Chen Jun , Yang Ying Li , Yang Hai Ying , Wang Ting Xun
Published: April 2014

The forming theory of elbow made by expanding diameter and pushing bend is introduced in this paper. The tube blank of elbow takes place combined deformation with compression deformation in the axial direction and in the circumferential direction. The compression deformation in the axial direction makes tube bending deformation under the restricted condition of ram-shape die, then the belly metal of elbow thicken after compression deformation, while the back metal of elbow don’t take part in deformation. The eccentric expanding diameter in the circumference direction ensures the thickened wall thickness flowing favorably from elbow belly to elbow back and supplying the reduced wall thickness of back elbow. Comparatively, the compression deformation and expanding diameter deformation of short radius elbow is larger than that of long radius elbow. According to metal flowing law, proper ram-shape die design and pushing rate, increasing heating temperature, improving temperature field distribution and lubrication condition can assure uniformity wall thickness.
Investigation on an Al/WC Composite Coating of A356 Alloy Fabricated by Mechanical Alloying
Authors: Zuo Min , Zhao De Gang , Wang Zhen Qing , Geng Hao Ran , Zhang Hui Jun , Pu Long
Published: April 2014

In this paper, Al/WC composite coatings on A356 alloy were prepared by mechanical alloying, and their mechanical properties were characterized. The processing parameters for mechanical milling treatment, such as the premixing process of Al and WC powders, the ball-to-powder weight ratio and the milling duration, have been optimized, and the optimum ball-to-powder weight ratio and milling time were determined to be 14:1 and 12 h, respectively. It was found that premixed Al and WC powders have no significant influence on Brinell hardness due to the powders adhering to the balls and milling tank wall. With the Al/WC composite coating, the Brinell hardness of A356 alloys can be significantly improved from 65 HBW to 115 HBW.
Effect of Heat Treatment on Positron Annihilation Lifetime of an Extruded Al-12.7Si-0.7Mg Alloy
Authors: Zhang Yan Hui , Wang Dong , He Chang Shu , Cao Xing Zhong , Zhang Lin
Published: April 2014

Positron annihilation lifetime can reflect the information of electronic density. Therefore this technique is very sensitive to the vacancies. Therefore positron annihilation technology (PAT) is a non-destructive testing technology for the investigation on the vacancy in pure metals and alloys. The vacancy defects of as-cast pure aluminium and the extruded Al-12.7Si-0.7Mg alloy before and after heat treatment were investigated by positron annihilation lifetime spectra. The results of positron annihilation lifetime spectra show that the lifetime of free positron annihilation in the pure aluminium alloy is 155 ps. The positron annihilation lifetime of the extruded sample is longer than the lifetime in the pure aluminium due to the formation of grain boundary and dislocation during the extrusion process. The positron annihilation lifetime of the extruded sample after heat treatment is shorter than that before the heat treatment, and it is longer than that of the pure sample.
TRIP Effect in a Hot-Rolled Low-Carbon High Strength Complex Phase Steel
Authors: Tan Xiao Dong , Liu Zi Quan , Xu Yun Bo , Yang Xiao Long , Wu Di
Published: April 2014

In the present work, a study has been made of the hot-rolling process for a transformation induced plasticity (TRIP) steel Fe-0.12C-0.5Si-1.4Mn-0.5Cr (wt%). The volume fractions of retained austenite before and after a deformation were determined by X-ray diffraction (XRD). The microstructure was characterized by optical microscope, scanning electron microscope (SEM) equipped with electron backscattered diffraction (EBSD) and transmission electron microscope (TEM). A uniaxial tension text indicated that the steel possesses ultimate tensile strength of 748 MPa with yield ratio of 0.7 and elongation of 20%. The steel with the volume fraction of retained austenite of 12.5 % exhibits significant TRIP effect.
Effect of Quenching Microstructure on the Formation of Reversed Austenite in 9Ni Steel
Authors: Yang Yue Hui , Zhang Xiao Juan , Yuan Shao Qiang , Li Jing
Published: April 2014

The microstructures of 9Ni steel by quenching at different temperatures were observed, and the effect of grain size on the formation of reversed austenite was investigated by XRD, SEM and EBSD. It was found that the reversed austenite formed easily because of the refined initial microstructure which could provide more nucleation sites. More austenite phase precipitates during tempering and stabilization because the alloying atoms can segregate into austenite easily through a short-range diffusion. Austenitizing at 750°C to 850°C for 60min coiuld causes slight coarsening of microstructure and refining of martensite packets with average size of about 5μm. Obvious coarsening occurs when austenitizing temperature is over 850°C.
Influence of Deoxidation Methods on Inclusions in Sub-Rapid Solidified Low Carbon Steel
Authors: Li Hui Gai , Sun Fei Fei , Zhao Dan , Zheng Shao Bo , Zhai Qi Jie
Published: April 2014

The size, distribution, content and type of inclusions under Al, Si-Mn, Ti deoxidized conditions in sub-rapid solidified low carbon steel were investigated using VLM, SEM and TEM. Results indicated that after deoxidizing by Al, Si-Mn and Ti, the largest size of inclusions was 7.5μm, 5.6μm and 6.5μm respectively. Large amount of inclusions were tiny and dispersed in the sub-rapid solidification condition. The number of inclusions was 5423 per mm2 and the size was mainly smaller than 4μm in Al deoxidized condition. After deoxidized by Si-Mn and Ti, the number of inclusions was much less than before, with the amount of 1307 per mm2 and 1819 per mm2, respectively, and most of them were smaller than 3μm. Type of inclusions varies with different deoxidizer. The inclusions produced by Al deoxidation were Al2O3 and Fe-O-S. Inclusions were Al2O3, Al-O-Mn-S, Si-O-Mn-S and MnS in Si-Mn deoxidation sample. Inclusions produced by Ti deoxidation were Al2O3, Al-O-Mn-S and Ti-O-Fe-Si-Mn-S.
Isothermal Bainite Transformation in Low Silicon TRIP Steel with Phosphorus Addition
Authors: Chen Peng , Yan Ji Jun , Shen Chun Yu , Xu Yun Bo , Wang Guo Dong
Published: April 2014

The low silicon transformation-induced plasticity (TRIP) steel with phosphorus addition is consisted of the microstructure of retained austenite, ferrite and bainite which produced by intercritical annealing and isothermal bainite transformation followed by rapid cooling. In this study, isothermal bainite transformation of different experimental parameters in low silicon TRIP steel with phosphorus addition was investigated in laboratory. The addition of cheap element phosphorus, which has the same effect of silicon in retard the kinetics of carbide formation during isothermal bainite transformation, can reduce the silicon content, improve surface quality, solve galvanizing problem and reduce costs. The effect of bainite isothermal temperature, intercritical annealing temperature and heating rates were investigated by dilatometric experiment on a push-rod Formastor-FII high-speed dilatometer with radio frequency induction heating. The high resolution observations, composition analysis and elements distribution of microstructure were carried out using the electron scanning microscopy of a field emission electron probe microanalyzer (JEOL JXA-8530F) operating at 20KV accelerating voltage.
Effects of Strain Rate on Dynamic Strain Aging of SA508-III Steel
Authors: Yuan Dan , Wang Lei , Liu Yang , Song Xiu , Liu Jia Hua
Published: April 2014

The dynamic strain aging (DSA) behavior of SA508-III steel was evaluated through tensile tests with different strain rates from 10-4 to 10-1s-1 at 350°C. The OM, SEM and TEM were carried out to observe the microstructures and fracture morphologies of the steel. The results show that the serrated flows appear in the stress-strain curves when the strain rate is between 10-3~10-2s-1, indicating that DSA occurs. Under the strain rate range, the tensile strength increases and the elongation and the reduction of area decrease. However, the fracture surface of the steel after tensile tests is still ductile. DSA in SA508-III steel at the strain rates from10-3 to 10-2s-1 is mainly caused by the interaction between the internal solute atoms and dislocations, which leads to the dislocations multiplication and the formation of sub-grain boundaries and dislocation cell structure.
Effect of Nd and Dy Addition on AZ91D Ignition Temperature and Microhardness
Authors: Ding Jian , Qin Lin , Li Yong Yan , Zhao Wei Min
Published: April 2014

Magnesium alloys are very active and readily ignite during heating and melting. In this study, the ignition-proof property of AZ91D with Nd and Dy addition was discussed, and the effects of these ignition-proof elements on the microstructure and microhardness of AZ91D investigated. The results show that the ignition-proof performance of magnesium alloy is improved obviously. The ignition resistance is attributed to the compact oxide films, which consist of MgO, Al2O3, Nd2O3, Dy2O3. When Dy content increased beyond 0.5%, the change tendency of ignition point of the alloy follows the shape of “v” curve, and the ignition point increased with Nd addition. The optimum composition of the newly developed magnesium alloy is AZ91D-3Nd-0.5Dy with the ignition point about 60K higher than AZ91D. And also AZ91D-3Nd-0.5Dy has fine microstructure and higher microhardness.
Influence of Various Heat Treatment on Corrosion Resistance of As-Extruded Mg-9Li-3Al-2.5Sr Alloys
Authors: Yu Yuan Qing , Peng Xiao Dong , Yi Hong Yu , Liu Jun Wei
Published: April 2014

The corrosion behavior of Mg-9Li-3Al-2.5Sr alloy, solution treated at 400°C for 3h with various aging temperature (Ta; Ta=75,100,125,150,175°C), was investigated in 3.5% NaCl solution by immersion test and polarization curve measurement. Experimental results suggest that the alloy aged at150°Cfor 6h exhibits the highest corrosion resistance while the alloy treated at 75°C for 6h presents lowermost corrosion resistance. The corrosion resistance of the alloy is related to the grain size and the distribution of Al4Sr compound. The segregation of intermetallic compounds can accelerate the corrosion process. It was found that duo to the proper solid-solution and aging treatment, intermetallic compounds were distributed evenly along the grain boundaries, which can reduce the corrosion rate and corrosion current. In addition,with the growth of grain, the decrease of the grain boundary area per unit volume lead to improvement of corrosion resistance of the alloys.
Hot Deformation Behavior of As-Cast Mg-9Gd-2.5Y-Nd-0.5Zr Mg Alloy
Authors: Yang Yong Biao , Zhang Zhi Min , Ren Feng Li , Wang Qiang
Published: April 2014

The elevated temperature flow stress behavior of Mg-9Gd-2.5Y-1Nd-0.5Zr magnesium alloy was carried out by Gleeble-1500 thermal mechanical simulator in the temperature range of 460-520°C and in strain rates of 0.0005~1s-1 at a strain of 0.6. The optical microscopy was used for microstructure characterization. The results showed that the flow stress increases with increasing strain rates and decreasing temperature. All the deformed magnesium alloy specimens show a dynamic recovery characters in the temperature range from 460~500°C, and show dynamic recrystallization characters at 520°C. The flow stress of this alloy can be represented by Zener-Hollomon parameter function, and values of related parameters A, α and n, are 2.24×1013s-1、0.027MPa-1 and 2.93, respectively. Its activation energy for hot deformation Q is 212.6kJ/mol.
Deformation and Damage Features of a 4.5% Re Nickel-Based Single Crystal Superalloy during Creep at Medium Temperature
Authors: Shu De Long , Tian Su Gui , Wu Jing , Guo Zhong Ge
Published: April 2014

The deformation and damage behaviors of a 4.5% Re nickel-based single crystal superalloy during creep at medium temperature were conducted by means of creep properties measurement and microstructure observation in the present investigation. The results show that the creep life of the superalloy was measured to be 226h at 820MPa/820oC, displaying a better creep resistance. After the alloy crept up to fracture, the γ′ phase in the region near fracture was contorted and coarsened, which is attributed to the severe plastic deformation. In the latter stage of creep, the main/secondary slipping systems were alternately activated to twist the γ′ and γ phases, which promoted the initiation of the cracks along the interfaces of γ′ /γ phases. And the micro-cracks may be propagated both along the direction vertical to the stress axis and along the direction of slipping traces, which is thought to be the main deformation and fracture mechanisms of the alloy in the latter stage of the creep.
First-Principles Investigation of the Site Occupancy and Elastic Properties of Y in γ-Co3(Al,W)
Authors: Yao Qiang , Wang Yan , Zhu Yu Hong , Zhu Xiao Lin
Published: April 2014

Site occupancy of Y in the γ′-Co3(Al,W) was predicted theoretically by first-principles calculations based on density functional theory. By computing total energy as a function of applied strain, the elastic constants of quaternary Co3(Al,W) were also predicted. The results suggest that Y preferentially occupies the W sites in Co3(Al,W). The calculation of heat of formation shows that the occupancy of Y on the W sites decreases the phase stability of Co3(Al,W). The theoretical calculation also shows that the L12 Co24Al4W3Y compound is ductile in nature.
Heat Treated Microstructure and Mechanical Properties of K492M Alloy
Authors: Li Xiang Hui , Li Lian , Tang Xin , Gai Qi Dong
Published: April 2014

The microstructure, tensile and stress rupture properties of K492Malloy have been investigated in the present study. The results revealed that γ matrix, γ′ phase, carbide and eutectic in the interdendritic region within grain interior and along grain boundary were observed after solidification. After heat treatment, γ' precipitates with two obviously distinct size existed in the dendrite core and interdendritic region, respectively. Meanwhile, the chain-like (W, Mo)6C and Cr23C6 carbides precipitated along grain boundary. The investigation of mechanical properties suggested that the tensile strength was initially increased but then decreased with increasing the temperature from 25oC to 760oC. The stress rupture life was 68.2h and 35.8h at 760oC / 655MPa and 870oC / 365MP, respectively. The columnar grain and carbide along grain boundary resulted in intergranular brittle fracture in both test conditions. As a result, the elongation under the conditions of 760oC/655MPa and 870oC/365MP was 1.5% and 1.4%, respectively.
Hot Deformation Characteristics of Spray Formed Nickel Based P/M Superalloy
Authors: Liu Na , Li Z. , Zhang G.Q. , Yuan H. , Xu W.Y. , Wang Y.
Published: April 2014

The hot deformation behavior of a nickel based P/M superalloy by spray forming and hot isostaticpressingwas investigated by isothermal compression test at Gleeble 3500 thermal mechanical simulator. The compression test was performed in the temperature ranging from 1025°C to 1150°C and in the strain rate ranging from 10-1/s to 10-3/s. The results show that the flow curves of true stress and true strain exhibit typical dynamic recrystallization and dynamic recovery. Compression temperature and strain rate have a strong effect on the dynamic recrystallization grain refinement.With higher strain rate the refined dynamic recrystallizationmicrostructure can be obtained at deformation temperature lower thanγ′solution temperature. Grain coarsening occurs at the deformation temperature close to γ′solution temperature, and the grain grows up obviously with decreasing strain rate.