bluuebunny/crossref_metadata_2025 huggingface dataset:
Recognizing Driving Behavior and Road Anomaly using Smartphone Sensors
Authors: Ali Aya Hamdy , Atia Ayman , Mostafa Mostafa-Sami M.
Published: June 2017

Road traffic accidents are caused 1.25 million deaths per year worldwide. To improve road safety and reducing road accidents, a recognition method for driving events is introduced in this paper. The proposed method detected and classified both driving behaviors and road anomalies patterns based on smartphone sensors (accelerometer and gyroscope). k-Nearest Neighbor and Dynamic Time Warping algorithms were utilized for method evaluation. Experiments were conducted to evaluate k-nearest neighbor and dynamic time warping algorithms accuracy for road anomalies and driving behaviors detection, moreover, driving behaviors classification. Evaluation results showed that k-nearest neighbor algorithm detected road anomalies and driving behaviors with total accuracy 98.67%. Dynamic time warping algorithm classified (normal and abnormal) driving behaviors with total accuracy 96.75%.
Feature Selection of Interval Valued Data Through Interval K-Means Clustering
Authors: Guru D. S. , Kumar N. Vinay , Suhil Mahamad
Published: June 2017

This paper introduces a novel feature selection model for supervised interval valued data based on interval K-Means clustering. The proposed model explores two kinds of feature selection through feature clustering viz., class independent feature selection and class dependent feature selection. The former one clusters the features spread across all the samples belonging to all the classes, whereas the latter one clusters the features spread across only the samples belonging to the respective classes. Both feature selection models are demonstrated to explore the generosity of clustering in selecting the interval valued features. For clustering, the kernel of the K-means clustering has been altered to operate on interval valued data. For experimentation purpose four standard benchmarking datasets and three symbolic classifiers have been used. To corroborate the effectiveness of the proposed model, a comparative analysis against the state-of-the-art models is given and results show the superiority of the proposed model.
Word-Level Multi-Script Indic Document Image Dataset and Baseline Results on Script Identification
Authors: Obaidullah S. K. , Santosh K. C. , Halder Chayan , Das Nibaran , Roy Kaushik
Published: June 2017

Document analysis research starves from the availability of public datasets. Without publicly available dataset, one cannot make fair comparison with the state-of-the-art methods. To bridge this gap, in this paper, the authors propose a word-level document image dataset of 13 different Indic languages from 11 official scripts. It is composed of 39K words that are equally distributed i.e., 3K words per language. For a baseline results, five different classifiers: multilayer perceptron (MLP), fuzzy unordered rule induction algorithm (FURIA), simple logistic (SL), library for linear classifier (LibLINEAR) and bayesian network (BayesNet) classifiers are used with three state-of-the-art features: spatial energy (SE), wavelet energy (WE) and the Radon transform (RT), including their possible combinations. The authors observed that MLP provides better results when all features are used, and achieved the bi-script accuracy of 99.24% (keeping Roman common), 98.38% (keeping Devanagari common) and tri-script accuracy of 98.19% (keeping both Devanagari and Roman common).
Optimal Release Policy for Multi-Release Software System
Authors: Aggarwal Anu G. , Jaggi Chandra K. , Nijhawan Nidhi
Published: June 2017

In software industry, multi release software development process is a latest phenomenon that brings the benefits of newer technologies, while retaining the quality. In this paper, it is assumed that the development of next version or release starts immediately after the launch of the previous version and the field test of each version continues after its release so that undetected faults of just previous version along with the added faults of latest version are detected during the testing of new software code. Today's dynamic customers need timely up gradation. Therefore, to sustain user growth and satisfaction it is imperative for the developers to know the appropriate time to launch upgraded software into the market. In this paper, an optimal release policy for multi release software system has been proposed by taking into consideration the testing as well as the operational phase. A numerical example has been presented to illustrate the optimal release policy. Parameter estimation has been done using the real-life fault data set. Goodness-of-fit curves have been drawn.
Implementing Risk Management Processes into a Cloud Computing Environment
Authors: Alhawari Samer , Jarrah Mufleh Amin AL , Hadi Wa'el
Published: June 2017

With the significant advances in Information and Communications Technology (ICT) over the last half a century, the Cloud computing paradigm is one of the most discussed topics in the field of ICT today. Additionally, Cloud computing has a critical role in today's business world. Without risk management processes embedded into innovative technology that supports Cloud computing, businesses are setting themselves up for a fall. Hence, in this paper, the authors propose a conceptual model of implementing risk management processes into a Cloud computing environment. It highlights the different processes of risk management (risk identification, risk analysis, risk planning, risk execution, and risk monitoring) and how their existence can affect the Cloud environment to ensure proper protection of data and information in order to ensure Cloud networks and connections are secure.
GIS Based Interoperable Platform for Disaster Data Exchange Using OGC Standards and Spatial Query
Authors: Abburu Sunitha
Published: June 2017

Accurate, speedy and interoperable information exchange among the stakeholders achieve effective rescue and relief operations in an emergency. The current research work aims at location-based real time or near real time disaster data gathering and accumulation. The dynamic disaster data is integrated with the static geospatial data to facilitate spatial analytics and disseminate the integrated data through OGC web services to various stakeholders for further processing by different expert domain applications. The research work also facilitates spatio-temporal querying system through Geo-query, and OLAP operations on integrated disaster data with geospatial visualization. The design and implementation of the work is achieved through a mobile application integrated with a GIS based web portal by a centralized remote server. The entire architecture has been tested by implementing in an emergency situation and facilitated by an effective interoperable information exchange and spatio-temporal queries.
Referees
Authors: Education Acta Scientiarum.
Published: June 2017

Referees for Volume 39, n. 3 of the Acta Scientiarium. Education, 2017
As Crônicas da Colonização: a produção literária sobre a imigração italiana na região da quarta colônia (1975)
Authors: Manfio Juliana Maria
Published: June 2017

A região da Quarta Colônia celebrou, a partir de 1975, as comemorações do Centenário da Imigração Italiana no Rio Grande do Sul. Para essas festividades, cada localidade preparou de sua forma, atividades como missas, desfiles, jantares, almoços. Além disso, como forma de divulgar o processo imigratório, padre Luiz Sponchiado – pároco do município de Nova Palma – produziu as crônicas da colonização, com o intuito de relatar o cotidiano dos imigrantes italianos na referida região colonial. O presente trabalho procura compreender o discurso propagado sobre a imigração italiana nas festividades dos 100 anos da imigração italiana na Quarta Colônia, através das crônicas da colonização. Será analisado o conteúdo desse material, para compreender o discurso propagado sobre o processo imigratório na região da Quarta Colônia.
Fabrication and Properties of In Situ B13P2 Reinforced Cu-Based Composites
Authors: Sun Zu Xin , Wu Yu Ying , Cui Xiao Li , Zhang Guo Jun , Liu Xiang Fa
Published: June 2017

In this work, a new type of B13P2 reinforced Cu matrix composite (B13P2/Cu) with excellent wear resistance properties has been fabricated. The experimental results reveal that when the total content of P and B was 3wt.% and the mass ratio of P to B was 2:3, the brittle reticular divorced eutectic Cu3P disappeared and B13P2 phase uniformly distributed in Cu matrix. The microstructure can be controlled and designed according to the ratio of P and B. The microhardness of B13P2 reached up to 1837 HV, which was as high as that of SiC, while the mircohardness of Cu matrix was about 5 times more than pure that of Cu. The wear resistance data indicate that the largest weight loss of pure Cu was approximately four times more than that of the B13P2 reinforced composites at the 40 min. The CTE of the new composites also decreased as compared with pure Cu.
Thermodynamic Calculation of Phase Equilibria in the Mn-RE (RE=Nd, Gd, Dy) Binary Systems
Authors: Rong M.H. , Lin S.D. , Wang Jiang , Zhou H.Y. , Rao G.H.
Published: June 2017

Ternary intermetallic compounds with rare earth elements and transition metals in the RE-Mn-X (X=Si, Ge, Sn etc.) ternary systems show interesting magnetic properties. As key sub-binary systems of the RE-Mn-X (X=Si, Ge, Sn etc.) ternary systems, the information of phase equilibria and thermodynamic properties of the Mn-RE (RE=Nd, Gd, Dy) binary systems are indispensable to explore the RE-Mn-X (X=Si, Ge, Sn etc.) alloys with better magnetic properties. In this work, the experimental data of phase equilibria and thermodynamic properties of the Mn-RE (RE=Nd, Gd, Dy) binary systems in the published literature were reviewed. Based on the available experimental information, thermodynamic calculation of phase equilibria of the Mn-RE (RE=Nd, Gd, Dy) binary systems was performed using the CALPHAD method. As a result, further experimental investigation and thermodynamic optimization would be still necessary in order to develop the self-consistent and compatible thermodynamic database of the RE-Mn-based alloy systems.
Effects of Electromagnetic Stirring Frequency on the Microstructure and Mechanical Properties of Al-7Si-0.42 Mg-0.1Cu Alloy by Semi-Solid Processing
Authors: Qi Peng , Li Bo Long , Lv Wen Jian , Wang Tong Bo , Nie Zuo-Ren
Published: June 2017

The effect of the different electromagnetic stirring frequency after low temperature pouring on microstructures and mechanical properties of Al-7Si-0.42 Mg-0.1Cu alloys was studied. It was found that the primary α-Al becomes smaller and tended to be spherical morphology, and the particles were uniformly distributed after electromagnetic stirring. The tensile strength of alloys improved gradually from 193.02 MPa to 212.54 MPa, and the elongation increased from 3.73% to 6.67% when the stirring frequency was 10 Hz. From the fracture morphology, the fracture for alloy stirred at frequency of 10 Hz showed more dimples than that without stirring. When the stirring frequency increased to 15 Hz, the microstructures of primary α-Al appeared to be dendritic structures, and the grains became coarse. As a result, the 10 Hz was the best electromagnetic stirring frequency.
Effects of Ultrasonic Impact Treatment on the Residual Stress and Microstructure of TA15 Welded Joint
Authors: Qian Guang Lu , Song Xiao Yun , Ye Wen Jun , Chen Rong , Ma Teng , Hui Song Xiao
Published: June 2017

The effects of ultrasonic impact treatment (UIT) on the distribution of residual stress and on the microstructure of TA15 (Ti-6.5Al-2Zr-1Mo-1V) alloy joints by electron beam welding (EBW) were investigated. The results demonstrated that a marked microstructure change occurred after welding and the microstructure of welded joint presented a transitional change, i.e. martensite appeared in the fusion zone while equiaxed α in base mental. The residual stress in fusion zone was mainly tensile stress, and the maximum longitudinal stress value was 817MPa, which located in the centerline of welded joint. The results indicated that different impact methods have different influence on residual stress distribution. After employing UIT on welding toe, the residual stress near the welded joint exhibited a uniform distribution and the maximum tensile stress dropped to-153MPa. While after applying UIT on full coverage, the curve of the residual stress was steep and the maximum stress was still tensile stress. After UIT, no significant change occurred in microstructure and the tensile strength has a little change.
Metal Magnetic Memory Testing of Welded Joints under Fatigue Load
Authors: Qiao Ning , Shan Mu Xiao , Li Ye Zheng
Published: June 2017

To investigate the influence of stress concentration, crack propagation and types of fatigue loading on metal magnetic memory signals, two groups of fatigue experiments with different types of fatigue loading were carried out on Q235B steel welded joint. The normal components of magnetic flux leakage were measured by metal magnetic memory tester in the course of fatigue test, and the fracture surfaces of specimens were observed by scanning electron microscopy after fatigue tests. The experimental results showed that the normal components of magnetic flux leakage filed, as well as the metal magnetic memory signal, changed polarity and their gradients have peak values at stress concentration zones. The zero position of the normal component of magnetic flux leakage changed gradually with increasing cycle numbers. In addition, the metal magnetic memory signal feature of fatigue crack propagation was affected by the loading type clearly. Moreover, a combination of brittle rupture and ductile rupture was obtained in the fracture morphology figure.
Mechanical Properties of Micro-Zones of X80 Pipeline Welding Joints
Authors: Guo Xiao Jiang , Xiao Jian , Cai Bi Lin , Zhang Guang Bin
Published: June 2017

Due to the inhomogeneous mechanical properties of laser welding joints, it is necessary that the local mechanical properties of welding joints are measured for the assessment of the whole welding joints. Especially for mechanical properties test in heat affected zone of welding joints. Two methods of micro shear test and hardness test to measure mechanical properties of micro-zones were introduced. Using these two methods the mechanical properties of the micro-zones of X80 pipeline welding joint are determined and compared. The results showed that the micro shear test could be intuitively, quantitatively and continuously describe the strength and plasticity of the regional heterogeneity distribution, suitable for the assessment of the mechanical properties and fracture toughness of welding joints.
Protective Ability of Graphite Powder on Molten AZ91D Magnesium Alloy
Authors: Li Wei Hong , Zhou Ji Xue , Ma Bai Chang , Wu Jian Hua , Wang Jin , Zhuang Hai Hua , Yang Yuan Sheng , Huang Xiao Hui
Published: June 2017

Graphite powder was used to prevent a molten AZ91D magnesium alloy from oxidation and burning in order to develop a new pollution-free protection method with low cost. The protection method is expected to have good protective effect without decreasing the mechanical properties of the alloy. The protective ability of graphite powder on the alloy was investigated. Experimental results showed that graphite powder could protect AZ91D melt. The protective ability increased with graphite powder amount and decreased with holding time. The microstructure, chemical composition and phase composition of the surface films formed on the molten AZ91D alloy were analyzed using scanning electron microscopy, energy dispersive spectrometer and X-ray diffraction, respectively. The protection mechanism was discussed. The surface films produced by the reactions between graphite powder, AZ91D alloy melt and the ambient atmosphere had two layers. The continuous and compact outer layer, mainly consisting of MgO and C, may be the fundamental reason for the fact that graphite powder could protect AZ91D alloy melt.
The Optimal Selection of Extrusion Parameters of As-Cast TC27 Titanium Alloy Based on Processing-Map
Authors: Li Xue Fei , Sha Ai Xue , Huang Xu , Huang Li Jun
Published: June 2017

The hot deformation behavior of TC27 titanium alloy at the temperatures of 900-1150 °C and the strain rate of 0.01-10 s-1, the height reduction of 70%, was investigated in the isothermal compression test to identify the optimal extrusion parameters. The processing-map of TC27 titanium alloy was constructed based on dynamic materials model (DMM) and principle of Prasad*s instability. The conclusion shows that temperature and strain rate of deformation had a great influence on flow stress. At the beginning of deformation, the flow stress increased quickly with the augment of true strain and decreased slowly after flow stress reaching to the maximum value. Finally, flow stress tended to relatively stable condition. The flow stress decreased with the increase of temperature and increased with the increase of strain rate. The TC27 titanium alloy was sensitive to temperature and strain rate. Processing-map exhibited two peak efficiencies of power dissipation; one peak was 49% at 900°C/0.01 s-1, which dynamic recovery occured. The other peak was also 49% at 1050 °C /0.01s-1, which dynamic recrystallization occured in the domain. Besides, there were two instability areas in the processing-map which should be avoided during the extrusion. Therefore, in order to obtain the satisfactory properties, the parameters that 1050 °C and 0.01 s-1 were selected in the extrusion.
Effect of Solution Treatment on Microstructure and Mechanical Properties of Hot-Extruded Cu-15Ni-8Sn Alloy
Authors: Wang Xun , Zhao Chao , Yu Yan Gen , Luo Zong Qiang , Zhang Wei Wen
Published: June 2017

The effects of solution treatment on the microstructure evolution of hot-extruded Cu-15Ni-8Sn alloy were investigated by optical microscope (OM), scanning electronic microscope (SEM), differential scanning calorimetry (DSC) and tensile testing, and the effects of solution temperature and time on the mechanical properties of the alloys were analyzed. The results indicated that, the γ-phases precipitated at first and then dissolved with the extension of the solution time during solutionizing at 800 C,the volume fraction of theγ-phase reached its peak at about 1h. However when solutionizing at 860°C, theγ-phase solely dissolved gradually with the extension of the solution time . In addition, a small amount of annealing twins appeared intragranular in the process of solution treatment. The γ-phase dissolution and the grain growth of α (Cu) were the main softening factors of the alloy during the solution treatment. Through overall consideration, the optimum solution treatment was annealing at 840°Cfor 1 h.
Numerical Simulation on Filling Optimization of Copper Rotor for High Efficient Electric Motors in Die Casting Process
Authors: Wu Ya Nan , Huang Guo Jie , Cheng Lei , Liang Daniel , Xiao Wei
Published: June 2017

The parametric optimization of process parameter in cold chamber die casting for an industrial component (copper motor rotors) was analyzed. The filling process was successfully simulated based on software FLOW-3D. The distribution of gas entrapment, temperature field and surface defect during the mold filling process were discussed in details. The numerical results showed that the pouring velocity had the most significant influence on the filling time, followed by the filling temperature and the die temperature. As for the filling properties, the effect of the pouring temperature was dominant. From the simulation results, the places of defect in the copper rotor were forecasted, and the reasons of the defect were well explained. Thus, the technological parameters could be improved in numerical simulation, and the simulation results would be further validated in practice.
Preparation of Micro-Hole with Large Aspect Ratio
Authors: Qu Ying Dong , Jin Mei Ling , You Jun Hua , Li Rong De
Published: June 2017

It was difficult to prepare micro-hole with large aspect ratio by traditional processing technologies. In order to solve the problem, a preparation was proposed. It was carried out by casting method. Carbon fiber and metal wire coated graphite paint were used as hole core respectively. And morphology and geometrical characteristic of micro-hole were observed and analyzed by scanning electron microscope and laser scanning confocal microscope. The results showed that average diameter and aspect ratio of micro-hole obtained by the group of carbon fiber hole core were about 0.2 mm and above 1700, respectively. For the other group, about 0.5 mm and 700, respectively. The micro-hole obtained by the metal wire coated graphite paint hole core was more close to circle. Its shape factor was about 0.72. The roughness of micro-hole value obtained by carbon fiber hole core was close to 3.2 μm, smaller than that of the metal wire coated graphite paint.
Influence of Cooling Rate and Chemical Composition on Phase Transformation and Hardness of C70S6 Steel
Authors: Ji Yan , Zhou Ning Bo , Sun Xiao Hang , Jiang Bo , Xiao Lei Lei , Liu Ya Zheng
Published: June 2017

The influence of cooling rate and chemical composition on phase transformation and hardness of C70S6 steel were studied by Gleeble-3800 thermal simulation testing machine and box type electric furnace. The results showed that when the cooling rate was between 0.3 and 5 °C/s, the transformation products of two experimental steels were mainly composed of ferrites, pearlite and sorbite. The pearlite content gradually decreased with the cooling rate increasing, while the sorbite content increased and the ferrite content changed little. Both the ferrite and pearlite transformation starting temperature and ending temperature decreased with the cooling rate increasing. Besides, the hardness increased with the cooling rate. At the same cooling rate, the phase transformation temperature increased slightly with the carbon equivalent decreasing, and the pearlite content increased, while the hardness decreased. The hardness of C70S6 steel was reduced by cooling rate decreasing. However, it was difficult to realize the method of decreasing the hardness by adjusting the cooling rate in the case of higher carbon equivalent. Therefore, in order to obtain an appropriate hardness, the Ceq must be controlled. And a Ceq=0.83% was recommended.
Manufactured Process of High Strength and High Electrical Conductivity Cu-Cr-Zr-Mg Alloy Bars
Authors: Gan Chun Lei , Liu Hui , Zheng Kaihong , Liu Yu Ning , Wang Hai Yan
Published: June 2017

A typical process was developed to manufacture Cu-Cr-Zr-Mg alloy bars with high strength and high electrical conductivity. The microstructure and properties of the alloys were investigated by observations of optical microscopy and scanning electron microscopy, and measurements of tensile strength and electrical conductivity. The results showed that the process and thermo mechanical treatments were successfully developed to manufacture Cu-Cr-Zr-Mg alloy bars with good combinations of the ultimate tensile strength (602.5 MPa) and conductivity (85.4% IACS). The achievement of high strength and high electrical conductivity in the alloy could be ascribed to the interactions of strain hardening and precipitation hardening.
Effect of High Density Electropulsing Current on Microstructure and Mechanical Properties of Fe-6.5wt.%Si Alloy Sheet
Authors: Liu Y.Y. , Liang Y.F. , Wen S.B. , Ye Feng , Lin J.P.
Published: June 2017

Fe-6.5wt.%Si alloy is an excellent soft magnetic material. Due to the appearance of ordering structures, the alloy shows poor ambient temperature ductility, and can only be cold rolled by specific rolling process. The rolling process with heat treatment is complex and time consuming. Meanwhile, high-energy electropulsing shows electroplastic effect. Heat treatment effect of the high-density electropulsing on microstructure and mechanical properties were investigated. The hot rolled sheet with 1 mm in thickness could be uniformly recrystallized in 33 s at 690 oC by appropriate high density pulses and the ductility was improved in comparison to the conventional heat treatment in a furnace. After the electropulsing treatment, the hot rolled sheet could be warm rolled by 50% reduction of the thickness after one pass without edge crack.
Effect of Bonding Temperature on Microstructure Development during Transient Liquid Phase Bonding of Ti2AlNb Alloy Using Ti-Zr-Cu Based Filler Alloy
Authors: Shen Li Jun , Liu Fen Cheng , Yang Gao Lin , Huang Yong De , Ke Li Ming
Published: June 2017

Transient liquid phase (TLP) bonding of Ti2AlNb, used for vacuum brazing furnace, was carried out using Ti-Cu-Zr based foil as filler alloy at 950, 1000 and 1050°C. The effect of bonding temperature on joint interface, phase constitutions and their distributions were investigated by taking advantages of OM, SEM, EDS and XRD analyses. The result revealed that the TLP joint consisted of isothermally solidified zone and diffusion affected zone. A non-isothermally solidified zone existed only when the bonding temperature was not high enough. The interface morphologies of the joints were found to be very sensitive to the bonding temperature. With the bonding temperature increased from 950°C to 1000°C, the width of non-isothermally solidified zone decreased from 69 μm to 23 μm. When the bonding temperature was 1050°C, the non-isothermally solidified zone disappeared. Meanwhile, more alloying elements of Cu and Zr diffused most adequately into the base material. Phase analysis showed that along with the increasing of bonding temperature, the secondary phase constitution of joint changed from Ti (Cu,Al)2 + AlNb2 + Ti solid solution to Ti solid solution + Nb (CuAl) + Al4Cu9 + Al2Zr3, and the proportion of secondary phase was 35.7%, 20.2%, 6.7%, respectively. The morphology of base metal changed because of the relatively high bonding temperature was higher than 980°C, the α→β transition temperature.
Pore Structure Analysis of Large Size Gasar Cu Ingot Prepared by Bridgman Method
Authors: He Yun , Li Yan Xiang , Zhang Hua Wei , Liu Yuan
Published: June 2017

Large size Gasar ingots have the advantage of cost saving and productivity improvement, while little attention has been paid to the preparation of large size ingots, especially those with high structural quality. Bridgman method was introduced to fabricate large size Gasar metal ingot. High quality Gasar Cu cylinder sample of 150 mm in diameter and about 200 mm in height (weighing about 20 kg) was obtained at a proper withdrawing velocity. Pore structure distribution at different heights and radii in the sample was measured and analyzed in detail using the image analyzing software. The results showed that the pore aspect ratio changed slightly along the sample height. All the other structure parameters including porosity, penetrative porosity, penetrative pore area and number ratio, pore diameter, pore length and the pore aspect ratio kept almost constant at heights of over 65 mm, while they all varied little along the sample radius. Most of the pores were straight and round. The results suggested that Bridgman method was feasible for the fabrication of large size high quality Gasar metal ingots. This would promote the commercial application of Gasar metals, such as Gasar Cu for micro-channel heat sinks.
Numerical Simulation of Temperature Field and Microstructure of a Wide Copper Plate during Warm Mold Continuous Casting
Authors: Yi Feng , Liu Xue Feng
Published: June 2017

Wide plates are mainly prepared through traditional cold mold continuous casting technology. A problem is cracking which caused by the non-uniform temperature field in solidification. Warm mold continuous casting is a new technology. Warm mold continuous casting of wide copper plate (section 500mm×12mm) was studies. Temperature field, solid/liquid interface and microstructure were analyzed by ProCAST software. By simulation, the optimal processing parameters: withdrawing speed was 60-80 mm/min, and the temperature of copper melt, mold and cooling water were 1200°C, 800-900oC and 20 oC, respectively. The temperature field in the width direction of the copper plate broad face was uniform, and the temperature decreased uniformly along the withdrawing direction. The temperature difference between center and edge was within 10 oC, and the temperature difference between narrow and broadfaces was within 25oC. Microstructure of plate contained ‘bamboo-like’ grains along the withdrawing direction.
Simulation Analysis of Aluminum Circular Tube in a Two-Stage Porthole Dies Extrusion Process
Authors: Xu Ning , Huang Dong Nan , Du Zhao Xin , Li You Lai
Published: June 2017

The single stage porthole die extrusion was largely applied in our research and industrial production. Two stage porthole die for a hollow aluminum tube, which added a pre-porthole die in front of the conventional porthole die, could slow down the metal deformation rate and control the metal flow uniformity. We performed a simulation of hollow aluminum extrusion in single stage porthole die and two stage porthole die. Through a series of numerical simulation based on Forge software, the advantage of two-stage porthole die extrusion, such as the surface quality of extruded profile, extrusion force, welding quality and die stress, was studied. The results showed that the pressure of welding and required extrusion force decreased and the surface quality of the extruded profile would be improved. Thus, we could prolong the work life of mandrel root by the means of this method.
Ceria Coatings Prepared by Sol-Gel Approach on AZ91 Magnesium Alloy
Authors: Han Hui Min , Wang Dan Tong , Yu Hua Qian , Zuo Min , Wang Li Hong , Zhao De Gang
Published: June 2017

The ceria coatings on AZ91 substrates were successfully synthesized by chemical conversion and the corrosion resistance of AZ91 samples with and without ceria coatings were evaluated by means of electrochemical corrosion in 3.5 wt.% NaCl solution. According to the parameters derived from the polarization date, the Icorr (the corrosion current density) values of the coated samples are smaller than that of bare one, indicating that the corrosion resistance of AZ91 alloys has been improved to some extent. The influence of fluoridated pretreatment, inter-layer heat treatment, sintering temperature and the layer of films on the performance of ceria coatings were also investigated. It was found that the inter-layer heat treatment has no influence on improving the anticorrosion resistance of AZ91 alloy. In comparison with the bare one, the Icorr of optimal sample is about 0.0219mA/cm2, which decreases by two orders of magnitude, indicating that the ceria coatings could significantly improve the corrosion resistance of AZ91 magnesium alloy.
Effect of Hot Deformation Parameters on Flow Behavior and Microstructure of Ti-6Al-4V-0.2O Alloy
Authors: Xiang Lin , Tang Bin , Kou Hong Chao , Shao Jie , Li Jin Shan
Published: June 2017

Isothermal compression tests were conducted to investigate the effect of hot deformation parameters on flow behavior and microstructure of Ti-6Al-4V-0.2O alloy. The experimental results show that the strain rate and height reduction have little effect on the volume fraction of primary α at a deformation temperature of 860 ̊C. At a deformation temperature of 940 ̊C, the volume fraction of primary α at a high strain rate (10s-1) is about 10% less than that at low strain rates (0.01s-1~1s-1). It may be one of the reasons for the significantly discontinuous yielding phenomenon. Another reason is that the dislocation density decreased suddenly due to the dynamic recovery. With the increasing strain rate and the decreasing deformation temperature, the volume fraction of irregular secondary α increases and lamellar secondary α decreases. And with height reduction increasing, the irregular secondary α increases firstly and then tends to be steady because of dynamic recovery and recrystallization.
Substrate Bias Dependent Microstructure and Properties of TC17 Titanium Alloy Coatings Deposited by Magnetron Sputtering
Authors: Wu Ming , Huang Hao , Li Hu , Zhang Kan , Wen Mao , Zheng Wei Tao
Published: June 2017

While matrix coated fiber method is used to fabricate SiC continuous fiber reinforced TC17 (Ti-5Al-2Sn-2Zr-4Mo-4Cr) matrix composites (SiCf/TC17), the properties of SiCf/TC17 composite are strongly affected by the microstructure and properties of TC17 alloy coatings in precursor wires. In this work, Vb(substrate bias) was adopted to tailor the microstructure and properties of TC17 coatings, and Vb dependent on microstructure, morphology, composition, stress, hardness and adhesion for TC17 coatings have been investigated by X-ray diffraction, scanning electron microscope, atomic force microscope, auger electron spectrometer, surface profiler and nanoindenter. The experimental results showed that all coatings crystallized with hexagonal structure (α-Ti). The migratory ability of incoming ions increased with increasing Vb from floating to-120V, and the smoothing growth surface and re-sputtering came into prominence with further increasing Vb, then the surface roughened again and accompanied by a transition of growth mode from column grains to compact-grain structures. As Vb increased, Al content increased while Ti content decreases. In addition, compressive stress and hardness showed a rising trend caused by ions implantation. Interface ions implantation and stress state acted together on the adhesive force between TC17 alloy coatings and SiC fiber.
Wear and Corrosion Behaviours of FeCrNiSi Alloy Coatings by Laser Cladding
Authors: Qi Yu Long , Chen Hai Yan , Shu Chen Yang , Zhao Xuan , Dong Li Hua , Yin Yan Sheng , Yang Zhi Chun
Published: June 2017

Soft and hard FeCrNiSi alloy coatings were obtained on 30CrMo alloy steel surface by laser cladding. The phase constitution, microstructure, frictional wear behavior and corrosion resistance of the composite coating were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), three-dimensional non-contact surface mapping, friction and wear testing machine and electrochemical workstation, separately.
XRD analysis showed that the cladding layer was mainly composed of Fe-based alloy composition, accompanied by a small amount of cobalt nickel alloy. There were massive protrusions in the interface of the soft sample, and the coating was regularly dendritic. Hard sample coating lines were cluttered, and there was no bulk deposition. Under the same wear condition, the soft coating exhibited serious abrasive wear, while the hard coating had slight abrasive wear behavior. The polarization curves in 3%NaCl solution revealed that the self-corrosion potential of the soft coating was positive shifted more than that the hard coating. The soft coating has better corrosion resistance than the hard coating.
NbN Thin Film of Alternating Textures
Authors: Shao Hong Yang , Zhang Kan , Zhang Yi Dan , Wen Mao , Zheng Wei Tao
Published: June 2017

The δ-NbN thin films with different thickness have been prepared by reactive magnetron sputtering at different deposition time and exhibited alternating textures between (111) and (200) orientations as a function of thickness. In addition, the grain size, peak position, morphology, residual stress and orientation distributions of the deposited films were explored by X-ray diffraction, low-angel X-ray reflectivity, scanning electron microscopy and surface profiler. The film deposited at 300 s showed a (111) preferred orientation, changing to (200) preferred orientation at 600 s, and exhibited alternating textures between (111) and (200) preferred orientations. With further increasing deposition time, in which (200) peak position and the full width at half maximum of (111) peak also displayed a trend of alternating variation with varying deposition time. The intrinsic stress for δ-NbN films calculated by Stoney equation alternately changed with alternating textures, in which (111) orientation always takes place at relatively high intrinsic stress state and vice versa. Meanwhile, the film with (111) preferred orientation showed higher density than (200) preferred orientation. The film deposited at 4800 s owned a mixed texture of (111) and (200), showing an anisotropy distribution of (111)-oriented and (200)-oriented grains, while film deposited at 7200 s owned a strong (200) texture, displaying an isotropy distribution of (200)-oriented grains. The competitive growth between (111)-oriented and (200)-oriented grains was responsibility for alternating texture.
Effect of WC and Co on the Microstructure and Properties of TiC Steel-Bonded Carbide
Authors: Li Hong Wei , Li Guo Ping , Chen Wen , Sun Li Hui , Luo Feng Hua , Du Yong , Wang Si Tao
Published: June 2017

TiC base high manganese steel-bonded carbide was manufactured with conventional powder metallurgy method to service in wear and impact resistant condition. WC was added in the alloy in the form of (W,Ti)C carbides to improve the impact toughness and expand the applications of alloy, meanwhile, cobalt powder was also used to enhance the wettability of the metallic binder on the ceramic phase. Results showed that the impact toughness of the alloy was increased remarkably with the increase of WC content. The impact toughness reached 10.6 J/cm2 when WC content was 10.5 wt.%, while the hardness of the alloy did not decrease. It was indicated that the appropriate content of WC and cobalt can improve impact toughness and wear resistance of the alloy greatly with little increase in the production cost.
Selective Electrolytic Corrosion Behaviours of WC in WC-Co Cemented Carbide
Authors: Li Zhong Wu , Lin Cheng Guang , Xie Xing Cheng , Cao Rui Jun , Lin Zhong Kun
Published: June 2017

In this work, WC grains in WC-Co cemented carbide were selectively electrolytic corroded and the effects of corrosion time, WC mean grain size and Co content on corrosion rate were systematically investigated. The results showed that corrosion rate decreased with the prolonging of electrolytic corrosion time. The WC-9Co cemented carbides had grain size of 2.9 μm The intensity of Co diffraction peaks was found to exceed the WC diffraction peaks when corroded for 4 hours, and the WC diffraction peaks disappeared when corroded for 8 hours. The corrosion rate increased with the decrease of WC mean grain size and the Co content. As the WC content increased in cemented carbide, it was necessary to increase corrosion time when analyzed Co phase in the cemented carbide by X-ray diffraction.
Effect of Micron-Scale SiO2 Surface Coating on the Strength of Chemically Strengthened Glass
Authors: Wu Ya Bin , Jia Ying Hui , Huang Yue , Zhou Zhong Hua , Shen Shirley
Published: June 2017

The influence of micron-scale SiO2 surface coating and orientation of the film surface on the strength of chemically strengthened glass was studied for the application to high speed train window glass. The glass samples with various thicknesses of 2 μm, 5 μm and 8 μm of SiO2 surface coatings on soda-lime silicate chemically strengthened glass were prepared and the strength of glass was tested by bicycle bending test when setting the coating surface to face up to or back to the impact. The results showed that the SiO2 film could significantly improve the bending strength of glass. Furthermore, the strength of the glass when coating surface backing to the impact was significantly greater than that when coating surface facing up to the impact. It might benefit from healing of cracks on glass surface by SiO2 coating.
Microstructure Evolution and Properties of 7A56 Aluminum Alloy by Homogenization
Authors: Xu Da , Li Zhi Hui , Wang Guo Jun , Jin Long Bing , Yan Hong Wei , Li Xi Wu , Zhang Yong An , Xiong Bai Qing
Published: June 2017

The microstructure evolution and properties of Al-matrix in homogenized 7A56 alloy were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), electrical conductivity and hardness test. The second phases in as-cast 7A56 alloy consisted of AlZnMgCu, Al2Cu and Al7Cu2Fe. With the homogenization temperature increasing, more non-equilibrium phase AlZnMgCu was dissolved into Al-matrix. The diffusion of alloying elements from AlZnMgCu phase into Al-matrix leads to a decrease of electrical conductivity and an increase of hardness. The lattice constant of α-Al has an increases of 0.0019 Å, 0.0032 Å and 0.0053 Å after 380°C/24h,430°C/24h,and 470°C/24 h treatment,respectively.
Preparation and Characterization of a Novel Hydrogel-Based Fouling Release Coating
Authors: Liu Lin , Li Zi Jie , Sun Sen , You Ting , Qi Xiao Tong , Song Kai
Published: June 2017

With the rapid development of marine transportation industry, biological fouling not only affects the speed of navigation but also highly increases fuel consumption. In the paper, a novel hydrogel-based fouling release coating is developed to address the issue by a combination of non-stick property with a low surface tension of the coating. A hydrogel-based silicone fouling release coating was synthesized and two kinds of different intermediate coatings were studied to give a proper match as the tie layer between the substrate coated with primer and the hydrogel silicone on the surface. The adhesion strength, surface tension as well as surface topography of the fouling release coating were studied. The corrosion resistance and anti-fouling performance of the substrates sprayed with the coating were characterized by salt spray test and immersion test in a simulated marine system. The results show that the adhesion between the substrate and the fouling release coating is grade two measured by grid test. The water contact angle of the coating is 104.8o and Rz of the coating is 10.71μm. The specimen is intact after 1000 hours under salt spray test. No diatom was found settled on the specimens in a simulated static marine system while a little diatom was observed on the specimens in a simulated dynamic marine system. It has been found that the intermediate coating comprising of epoxy resin gives proper match between the primer and the fouling release coating consisting of PDMS resin. The coating exhibits superior anti-fouling performance under stationary state.
Effect of Molten NaCl on the Synthesis of Ti3SiC2 Powders
Authors: Guo Xue , Wang Jun Xia , Yang Shi Yuan , Feng Yu Run , Gong Hong Yu , Zhang Yu Jun
Published: June 2017

Free Ti/Si/C powder mixtures with or without molten salt were heated under vacuum with various schedules. The effect of molten salt during synthesis on the morphology and phase composition of Ti3SiC2 powders were investigated. The combustion powders were analyzed by DSC, XRD, SEM and EDS. The results indicated that the existence of molten salt could promote the reaction process and decrease the synthesis temperature. The Ti3SiC2 powders obtained by molten salt method were uniform and well dispersive. The content of Ti3SiC2 phase was influenced by salt/powders ratio and molding pressure. The appropriate salt/powders ratio and pre-press pressure were 1:1and 100 MPa, respectively.
Synthesis and High-Frequency Absorption Property of Flower-Like Nickel-Ferrite Composites
Authors: Zhang Guang Qiang , Dong Hang Rong , Li Zong Zhen , Zhou Shao Xiong , Wang Yu , Zeng Min
Published: June 2017

Three-dimensional flower-like nickel-ferrite composites were successfully synthesized via decomposition of the nickel-iron alkoxide precursors by varying the ratio of iron and nickel ion in the solution. The overall morphology and size of the particles had no obvious change compared with the precursors. The high-frequency absorption properties of the composites were investigated in a frequency range of 2-18 GHz. The reflection loss and bandwidth varied with the nickel ratio and thicknesses of the compositions, showing valuable prospect in high-frequency wave attenuation. The wave absorbing mechanism was also discussed, which could be attributed to the dielectric loss, magnetic loss, and the synergetic effect.
High Permeability of Z-Type Ferrite Sheets Directional Array
Authors: Pan Shi Bing , Zhang Cheng Jun , Wu Hai Kun , Qian Lei , Yu Ming Xun , Fan Run Hua
Published: June 2017

Z-type ferrite sheets were prepared by chemical precipitation method to investigate influences of directional arrays from the Z-type ferrite sheets on magnetic properties. The permeability of the ferrite directional arrays was obviously improved in the specific direction. Assuming that the intrinsic permeability of Z-type ferrite was existed, the magnetic permeability in array was calculated by the Maxwell-Garnett equation of effective media theory. The reason for the large difference between the theoretical calculation and measured value was also discussed.
Dielectric and Magnetic Properties of Cermets with Iron-Aluminum Dual Metallic Particles
Authors: Sun Kai , Wang Zhong Yang , Xie Pei Tao , Fan Run Hua
Published: June 2017

The dual metallic components, i.e., iron-aluminum particles were distributed in alumina matrix to fabricate lossy cermets. The electromagnetic parameters including ac conductivity, the complex permittivity and permeability were investigated. With the increase of filler fractions, the conductive carriers instead of the dipoles played a primary role in conductive and dielectric properties. Hopefully, the cermets composites could be promising candidates for electromagnetic wave attenuation and shielding.
Synthesis and Thermoelectric Properties of ZnO/Cu2SnSe3 Composites
Authors: Ning Ji Ai , Zhao De Gang , Jia Peng , Wu Di
Published: June 2017

Addition of nanoparticles into bulk materials is an efficient way to enhance the performance of thermoelectric materials. The nanoZnO particles were introduced into the Cu2SnSe3 matrix by ball milling method, and the ZnO/Cu2SnSe3 composites were fabricated by spark plasma sintering (SPS) technology. The phase constitution and microstructure were characterized by XRD, FESEM. The effects of nanoZnO particles on the electrical and thermal transport were investigated and discussed. The diffraction spectra of all composites samples well corresponded to that of the matrix diffraction plane. The nanoZnO agglomerated into irregular clusters with the size lager than 200nm and distributed on the grain boundary or the surface of Cu2SnSe3 grain, which significantly reduce the lattice thermal conductivity by scattering middle-long wavelength phonons. The optimal ZT value was obtained from the composite sample of 2.4 vol. % ZnO, which is 1.3 times as large as that of the Cu2SnSe3 matrix.
Fabrication of High Purity MgO Ceramic Targets by Hot-Isostatic Pressing
Authors: Chen Miao Qin , He Jin Jiang , Ding Zhao Chong , He Xin
Published: June 2017

MgO ceramics with the purity higher than 99.99% have been fabricated by a hot-isostatic press (HIP) technique of hot-pressed MgO compacts using nanometer MgO powder with an average particle size of 300 nm. The densification and grain growth behavior of MgO compacts during HIP process were investigated. The results indicate that the high-purity MgO ceramic with an average grain size of 9.76 μm and a density approximately to the theoretical density can be obtained by HIP method at 1350°C and 150 MPa for 60 min. HIP can significantly enhance the densification process of MgO compacts and cause a slightly change of grain size distribution.
Effect of Deformation Temperature on Texture Evolution of TLM Titanium Alloy
Authors: Bai Xin Fang , Zhao Yong Qing , Li B.
Published: June 2017

In this work the texture evolution of a near β Ti-3Zr-2Sn-3Mo-25Nb (TLM) biomedical titanium alloy in hot compression at different deformation temperatures from 750°C to 850°C has been investigated. The XRD examination shows that the samples of hot deformation consist of β phase only. The development of texture has been explained in terms of orientation distribution functions (ODFs) of α and γ fibres. Compared with cold compression of TLM alloy, the texture changes obviously with the increase of deformation temperature. The {111}<110> texture shows the feature that weaken firstly and then strengthen, while the {111}<112> texture shows an opposite tendency. Specifically, the prominent texture components change to the {111}<110> and {111}<112> at the deformation temperature of 850°C, which are the same texture type and the nearly level of orientation density with the starting materials.