bluuebunny/crossref_metadata_2025 huggingface dataset:
A Distributed Method for Two Simultaneous Events Detection in WSNs
Authors: Moradi Mina , Ghaisari Jafar , Askari Javad , Gorji Mohammad
Published: December 2011

It is important to detect multi simultaneous events in Wireless Sensor Networks (WSNs). WSNs are usually consist of tiny sensor nodes which are often deployed in harsh environment and facing the fault conditions. In this paper, a fault tolerant distributed two-event detection method based on the Bayesian approach is proposed for WSNs. In addition, a data fusion algorithm is employed to involve the statuses of the neighborhoods in the decision of each sensing point. The proposed distributed method is used to detect two events simultaneously in a WSN with 200 sensors that distributed randomly. Also some random faults occur in all sensing nodes. Results show the accuracy and significant performance of the proposed two events detection approach.
Assisted Research of the Neural Network with LabVIEW Instrumentation
Authors: Olaru Adrian , Olaru Serban
Published: December 2011

The paper open the way to the assisted choose of the optimal neural network. There are shown some important neurons type, transfer functions, weights and biases of neurons, and some complex layers with different type of neurons in a static and dynamic networks. By using the proper virtual LabVIEW instrumentation were established some influences of the network parameters to the number of iterations till canceled the mean square error to the target. Were presented the simulation of some different neural network types like linear, sigmoid, sigmoid bipolar and radial. For some of more important, were presented the complex mathematical models and numerical simulation using the proper teaching law.
On the Interface between Plasma Fluorocarbon Films and 316L Stainless Steel Substrates for Advanced Coated Stents
Authors: Cloutier Maxime , Turgeon Stéphane , Chevallier P. , Mantovani D.
Published: December 2011

As intravascular biomedical devices, metallic stents are particularly susceptible to corrosion induced by the physiological environment, causing the degradation of mechanical properties and leading to the release of toxic and carcinogenic ions from the SS316L bulk. Therefore, several works have been focused on the development of an ultra-thin fluorocarbon coating that could act both as a drug-carrier for in-stent restenosis and as an anti-corrosion barrier. However, the increase of the corrosion performance was limited by the inevitable permeability of the coating, which exposed some of the sensitive interfacial region to the corrosive environment. Indeed, in previous works, adhesion and growth rate of the film were promoted by the removal of the native oxide layer of the stainless steel which is inhomogeneous, brittle and mechanically unstable. Further refinements of the interface are therefore required in order to enhance the overall corrosion performance without compromising the fluorocarbon film properties and adhesion. Hence, the aim of this work was to enhance the corrosion behaviour of coated SS316L by the creation of a controlled interfacial oxide layer. The native oxide layer was first removed under vacuum and the bare metal surface was subjected to a plasma-reoxidation treatment. Tafel measurements were used to assess the corrosion rates of the specimens. Coated and uncoated modified interfaces were also characterized by X-Ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM).
Why Mechanical Properties of Collagen Scaffolds Should Be Tested in a Pseudo-Physiological Environment?
Authors: Meghezi Sébastien , Chevallier P. , Mantovani D.
Published: December 2011

Collagen gels constitute an adequate scaffold for supporting the adhesion, proliferation and tissue regeneration of vascular cells inside a bioreactor. However, their mechanical properties should be enhanced not only for their manipulation but also to resist the mechanical constraints applied in the bioreactor. Actually, assessing the mechanical properties of a hydrogel requires many precautions since they are very sensitive to the environmental conditions (temperature, ionic strength, aqueous environment, etc). Whereas mechanical properties are usually measured directly in the air, the aim of this work was to evaluate the effects of a pseudo-physiological environment (PPE) on the mechanical properties of collagen gels. Furthermore, reinforcement was also tested using UV treatments (λ = 254 nm, 20 J/cm2), known to induce crosslinking. Irradiated samples were more resistant to enzymatic degradation and swelling tests showed that the crosslink density was increased by a factor of 30. This increase was thereafter correlated to the mechanical properties. Results showed that the UV-treated samples were stiffer and more brittle than the non-treated ones when tested in air. However, a 20% decrease and 40% increase were respectively measured on the linear modulus and strain at rupture when the gels were tested in the PPE. In the perspective of vascular tissue regeneration, these results show that the mechanical properties of a hydrogel should be performed in PPE in order to take into account the plasticization phenomenon that will occur in a bioreactor.
Investigating the Potential of TiB2–Based Composites with Ti and Fe Additives as Wettable Cathode
Authors: Heidari Hamed , Alamdari Houshang , Dubé Dominique , Schulz Robert
Published: December 2011

In this work, porous TiB2 ceramics were consolidated by pressureless sintering method using metallic Ti and Fe as additives in order to perform sintering at temperatures lower than 1700°C. It was shown that processing parameters including milling time of the starting mixture had a considerable effect on final properties of sintered specimens and their behavior in molten aluminum. Microstructural studies were carried out using optical microscope, SEM and EPMA. It was found that specimens with uniform and crack-free microstructure could be produced using the pre-mixed powders milled for as low as 30 min prior to compaction and sintering. Sessile drop test was performed on the specimens milled for 30 and 240 minutes. Their interaction with molten aluminum was also studied. It was found that 30 min milling time resulted in better electrical conductivity, wettability and stability in liquid aluminum.
The Brittle-to-Ductile Transition Behaviour in Fe-Al Single Crystalline Alloys
Authors: Maeno Keiki , Tanaka Masaki , Higashida Kenji , Fujikura Masahiro , Ushioda Kohsaku
Published: December 2011

The morphology of deformation twinning, which influences a brittle fracture at low temperatures, was investigated in Fe-8mass%Al. Tensile tests were performed at 129K and room temperature. The specimen tested at room temperature showed yielding and kept deformed by usual slip while the specimen tested at 129K fractured in a brittle manner in an elastic regime with a number of straight markings due to deformation twinning. Detail analysis of those deformation twins suggests that the collision of deformation twinning is the initiation site of the brittle fracture.
Microstructure, Mechanical and Corrosion Behaviour of AN AA2024-T3 FSW Joint
Authors: Bousquet Emilie , Poulon-Quintin Angéline , Devos Olivier , Puiggali Monique , Touzet Marie
Published: December 2011

The FSW weld consists of three distinct microstructural zones. The microstructure inside each zone is directly impacted by the FSW process parameters. The aim of this article is to correlate microstructure, microhardness and corrosion sensitivity of a AA-2024-T3 FSW joint for one processing parameter set. A microstructural analysis has been conducted in each weld zone by the combination of TEM observations, chemical and DSC analysis. Moreover, a small electrochemical cell was used to estimate the corrosion sensitivity of the distinct zones by localized open circuit potential measurements all along the weld. Mechanical properties were evaluated using Vickers microhardness measurements. The results show a direct correlation between mechanical property evolution, local corrosion process involved and microstructure modification.
Catalytic Properties of TiNi Foils for Methanol Decomposition
Authors: Sakurai Junya , Xu Ya , Demura Masahiko , Hirano Toshiyuki , Tamura Ryuji
Published: December 2011

The catalytic properties of the cold-rolled foils of intermetallic compound TiNi were studied for hydrogen production from methanol in a temperature range of 513-793 K. The catalytic activity for methanol decomposition increased with a reaction temperature, especially above 673 K. The SEM and EDS analyses revealed the formation of numerous Ni-enriched particles dispersed in the layer of carbon fibers during the reaction. The catalytic activity of TiNi foils is attributed to those Ni-enriched particles.
Evolution of as-Cast Microstructure of Mg-Al Alloys with Solute Content and Cooling Rate
Authors: Paliwal M. , Kang Dae H. , Essadiqi Elhachmi , Jung In Ho
Published: December 2011

Although numerous solidification experiments have been conducted for Al, Cu and Si alloys to investigate microstructural features like primary and secondary dendrite arm spacing, solute distribution with in secondary arms and second phase fraction, no systematic solidification study on Mg alloys has been performed to understand the evolution of microstructural features as a function of cooling rate and solute content. The present study focuses on the experimental microstructural evolution of Mg-3, 6 and 9 wt. % Al alloys in the cooling rate range of 1 K/sec to 1000 K/sec. The results suggest that secondary dendrite arm spacing and amount of second phase formation are strongly dependent on both solute content and cooling rate.
Effect of Dimensional Variation on Induction Process Parameters Using 2D Simulation
Authors: Barka N. , Bocher P. , Brousseau J. , Arkinson P.
Published: December 2011

The induction heating is a surface heat treatment that exhibits some relevant industrial advantages. In fact, the process is not energy-consuming compared to thermo-chemical processes such as carbonizing and nitriding because it allows generating high power and focusing it locally and during a short time to achieve hardness at the surface area without affecting the part core. Using no plating phase, the induction heating process is qualified as green and sustainable manufacturing process but should be better understood to help developers to reach optimized recipes in a small number of process iterations. Globally, for a given range of parts to be manufactured, one has to proper select the frequency and power of the equipment to be. This work will show how part geometry, generator frequency and power are closely linked. This work is carried principally by simulation efforts using computer-modeling software (COMSOL). A developed 2D model includes the coupling between electro-magnetic and thermal fields, and takes account of the non-linear behavior of material properties versus temperature. The simulation allows optimizing the machine according to the dimensions of gear. This paper also proposes a method to approximate the power amount required to achieve a desired hardness profile.
Preparation of Nanostructured Superhydrophobic Copper and Aluminum Surfaces
Authors: Huang Ying , Sarkar Dilip K. , Chen X. Grant
Published: December 2011

Preparation of nanostructured superhydrophobic surfaces requires both an optimum roughness and low surface energy. Application of a direct voltage between two copper plates immersed in a dilute ethanolic stearic acid solution transforms the surface of the anodic copper electrode to superhydrophobic due to the formation of micro-nanofibrous low surface energy flower-like copper stearate as confirmed by scanning electron microscope (SEM). Nanostructured superhydrophobic aluminum surfaces have also been prepared by electrodeposition of copper films on aluminum surfaces followed by electrochemical modification by ethanolic stearic acid. The X-ray diffraction (XRD) analyses confirmed the formation of copper films on aluminum substrates. The electrodeposited copper films are composed of microdots of copper whose density increases with the decrease of deposition potential as observed by SEM. The deposited copper microdots on aluminum substrates were electrochemically modified to low surface energy copper stearate nanofibres to obtain superhydrophobicity. The copper films deposited at potentials above-0.6 V did not exhibit superhydrophobic properties. However, the copper films deposited at potential-0.6 V and below exhibited superhydrophobic properties with water drop rolling-off those surfaces.
Surface Modification of Al Components Using Spark Plasma Sintering
Authors: Milligan Jason , Brochu Mathieu
Published: December 2011

A strong push has been observed in the automotive industry to replace current components with high-performance and lightweight materials such as aluminum alloys. Novel monolithic materials such as bulk nanostructured materials, cannot always offer the best performance in hostile environments and often have high manufacturing costs. This has required the development and engineering of processes to allow nanostructured surface functionalization of conventional materials. This processing strategy, similar to the metal-ceramic joining approach, exploits the advantages of both materials while reducing overall manufacturing costs. Spark Plasma Sintering (SPS) will be evaluated as potential a method for manufacturing a nanostructured Al-Si cladding. This novel coating method has a significant advantage over traditional processes in that it forms metallurgical bonds at both the interface and throughout the deposited layer to produce a coating with isotropic properties. The objective of this work is to create a nanostructured eutectic Al-Si feedstock powder and simultaneously consolidate and clad the powder onto a forged aluminum substrate using Spark Plasma Sintering. Results show that after mechanical milling, the aluminum grain size was refined to 47nm. The results also show that SPS is capable of sintering the powder in extremely short sintering times while maintaining nanostructure, and that the heating rate has a large effect on increasing densification rates. Mechanical properties of the resultant coating were also investigated.
Identification of Iron Rusts on Rail by X-Ray Diffraction and Vibrational Analysis
Authors: Sone Yasutomo , Suzumura Junichi , Kamura Naoya , Sasaki Toshihiko
Published: December 2011

A periodical unevenness of the running surface of rails is formed on ascending slope of submarine railway tunnel. One of the causes has been concluded due to the combination of a low friction and wheel load variation induced by some kinds of iron oxides and oxyhydroxides with various coefficients of friction on the rail, though it has not been made clear yet. In this study, X-ray diffraction and Raman scattering spectroscopic analysis were attempted to identify iron rusts on the rail as a process to solve the periodic unevenness of the rail suffering many railway companies.
Simulation of Grain Growth of Materials Produced by Severe Plastic Deformation
Authors: Mizuno Yuichi , Okushiro Kenji , Saito Yoshiyuki
Published: December 2011

Grain boundary migration in materials under severe plastic deformation was simulated by the phase field methods. The interface energy and dislocation density on growth kinetics were simulated on systems of 2-dimensional lattice. .In inhomogeneous systems grain size distributions in simulated grain structures were binodal distributions. The classification of the solution of differential equations based on the mean-field Hillert model describing temporal evolution of the scaled grain size distribution function was in good agreement with those given by the Computer simulations. Effect of dislocation on thermodynamic stability was taken into consideration. Dislocation density distribution was calculated by a equation based on the diffusion-reaction equation.. Scaled grain size distribution was known to be affected by the dislocation.
Characterization of Piezo Fiber-Based Sensors Responses in Multifunctional Composites
Authors: Mehdizadeh Mohammad , John Sabu , Wang Chun H. , Verijenko Viktor , Callus Paul
Published: December 2011

Structural health monitoring systems (SHMS) are increasingly being considered for implementation in a wide range of industries, including transport, civil infrastructure, and energy production. As the application of SHM systems increase, it will be increasingly important to quantify the durability, reliability, and reparability of the SHM system. This paper investigates the electrical and electro-mechanical characteristics of piezoelectric sensors in an attempt to distinguish sensor failure from structural damage [10]. This study involved the measurements of pertinent electrical properties for MFC (Macro Fibre Composite) sensor under fatigue loading and comparison of the strain measurements to characterize the degradation of the structure as well as the MFC. Changes in the capacitance and inductance of this sensor have been recorded, highlighting deleterious structural changes in the sensor itself without any discernible change in the structure being monitored.
Microstructure Characterization of White Layer Formed by Hard Turning and Wire Electric Discharge Machining in High Carbon Steel (AISI 52100)
Authors: Hosseini S. B. , Klement Uta , Kaminski J.
Published: December 2011

White layers, formed during hard turning and wire electric discharge machining, were characterized by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Different cutting speeds and flank wear were utilized in order to obtain different thermally and/or plastically deformed white layer. Since the white layer after wire electric discharge machining is mainly thermally induced, it was used as a reference structure. In the investigation, both bainitic and martensitic structures were studied. With a constant flank wear of 0.175 mm the thickness of the white layer increased from 1.5 μm to 3 μm as the cutting speed was increased. In both processes the white layer were characterized by nanosized grains and surface tensile residual stresses. M3C carbides were observed in the hard turned white layer, indicating that the time and temperature needed for completely dissolving the carbides were not reached during cutting. For both materials the white layers formed by wire electric discharge machining consisted of ~ 30 vol. % of retained austenite. Observation regarding the volume fraction of the retained austenite in the white layer formed by hard turning for martensitic material showed an increase in the volume fraction of retained austenite from ~ 2 - 3 vol. % to ~ 6 vol. %, while this observation was not seen in the white layer formed in the bainitic material.
Precipitation of Si and its Influence on Mechanical Properties of Type 441 Stainless Steel
Authors: Juuti Timo J. , Karjalainen L. Pentti , Heikkinen Eetu Pekka
Published: December 2011

In this study the precipitation of silicon in Type 441 steel (18%Cr-0.4%Nb-0.5%Si) was investigated and its influence on strength properties were determined. To simulate high-temperature service conditions, heat treatments with various ageing times up to 120 hours and temperatures up to 800 °C were performed. Following the aging treatments, micro-and macro-hardness and tensile properties were measured. Microstructure and precipitation were analyzed using scanning electron microscopy and energy-dispersive spectroscopy. Predictions for equilibrium pericipitation were calculated using the Factsage software. According to observations, coarse titanium nitrides (TiN) and niobium carbides (NbC, Fe3Nb3C) were present in all specimens including non-aged ones. These precipitates did not coarsen during ageing, which implies that their growth already occurred in the sheet production process. However, silicon started to precipitate in the course of prolonged annealing. Si contributed to the formation of a secondary phase resembling the Laves-phase (FeNbSi) on grain boundaries. Hardness and yield strength were found to decrease with prolonged ageing at high temperatures. Factors affecting the silicon precipitation are discussed.
Carbon Distribution and the Influence on the Tempering Behaviour in a Hot-Work Tool Steel Aisi H11
Authors: Lerchbacher Christoph , Zinner Silvia , Leitner Harald
Published: December 2011

The microstructure of the common hot-work tool steel AISI H11 has been characterized by atom probe tomography with the focus on the carbon distribution after the hardening treatment and in the early stages of tempering. The carbon distribution shows significant differences within the probed volumes, regions differently affected by carbon segregation can be observed in some specimens. In all samples pronounced carbon segregation to dislocations and cluster formation is observed. Through all hardened samples no segregation of any substitutional elements has taken place. Heating to 500°C does not significantly change the elemental distribution. Carbon enriched interlath austenite films with peak carbon levels of 6 to 9 at% show a thickness increase with increasing λ. These films and the pre-existing carbon clusters have been found to be nucleation sites for carbide formation during heating to 610°C.
Evolution of Microstructure and Mechanical Properties during Annealing of Cold Rolled Fe-24Mn-3Al-2Si-1Ni-0.06C Twip Steel
Authors: Saleh Ahmed A. , Gazder Azdiar A. , Santos Dagoberto Brandao , Pereloma Elena V.
Published: December 2011

TWinning Induced Plasticity (TWIP) steels have been recently developed as a promising material for automotive applications. In the present work the recrystallisation behaviour of 42% cold-rolled Fe-24Mn-3Al-2Si-1Ni-0.06C TWIP steel was investigated during isochronal annealing for 300s via microhardness testing, Electron Back-Scattering Diffraction (EBSD) and uniaxial tensile testing. EBSD internal misorientation data corroborates recrystallised fraction estimates from microhardness measurements. Annealing twins play an important role during recrystallisation by bulging at the deformed grain boundaries during nucleation and generating twin related orientations. During uniaxial tension, the recovered condition recorded three work hardening regions while all partially recrystallised samples exhibited four regions. A modified Hollomon scheme is suggested to account for the effect of strain on microstructure refinement.
Characterization of Microwave Plasma for Polymer Surface Modification Using FTIR Emission Spectroscopy
Authors: Mavadat Maryam , Turgeon Stéphane , Ricard André , Laroche Gaetan
Published: December 2011

Infrared (IR) emission spectroscopy measurements were performed in N2 microwave discharges at pressures ranging from 0.5 to 3 Torr and powers of 200 and 300 W. Although emission spectroscopy in the infrared region has rarely been investigated, this technique has nevertheless provided numerous key data. For instance, numerical generation of spectra to match experimental FTIR emission data allowed estimating the plasma temperature.
Oxidation Resistance of Al-Rich Aluminide Coating on TiAl Based Alloy by Thermal Spray and Diffusion Treatment
Authors: Yagi Takahiro , Sasaki Tomohiro , Watanabe Takehiko , Yanagisawa Atsushi
Published: December 2011

Al-rich aluminide coating on Ti-49.1at%Al alloys has been performed by two-step process of thermal aluminum spray and diffusion treatment. Effect of the diffusion time on the oxidation resistance, and the change of microstructures in the coating during the oxidation test in air at 900°C for 100 h were investigated. In the aluminized coating before the oxidation tests, formations of TiAl3 on the outer layer and an intermediate layer consisting of Ti2Al5, TiAl2, and Al-rich TiAl were observed. The intermediate layer developed by the diffusion treatment for 3600s. In the oxidation test over 50 h, the specimen diffusion treated for 3600 s exhibited the lower oxidation rate than that diffusion treated for 900 s. Multi-oxide scales of TiO2 and Al2O3 were observed on the both surfaces of aluminized specimens. Large TiO2 particles were observed on the specimen of tD = 900 s. It was found that the TiAl2 layer developed during the oxidized specimen, while the thicknesses of Al-rich TiAl and TiAl3 layer decreased by the growth of TiAl2.
Solid Freeform Fabrication of Al-Li 2199 via Controlled-Short-Circuit-MIG Welding
Authors: Heard David W. , Boselli Julien , Gauvin Raynald , Brochu Mathieu
Published: December 2011

Aluminum-lithium (Al-Li) alloys are of interest to the aerospace and aeronautical industries as rising fuel costs and increasing environmental restrictions are promoting reductions in vehicle weight. However, Al-Li alloys suffer from several issues during fusion welding processes including solute segregation and depletion. Solid freeform fabrication (SFF) of materials is a repair or rapid prototyping process, in which the deposited feedstock is built-up via a layering process to the required geometry. Recent developments have led to the investigation of SFF processes via Gas Metal Arc Welding (GMAW) capable of producing functional metallic components. A SFF process via GMAW would be instrumental in reducing costs associated with the production and repair of Al-Li components. Furthermore the newly developed Controlled-Short-Circuit-MIG (CSC-MIG) process provides the ability to control the weld parameters with a high degree of accuracy, thus enabling the optimization of the solidification parameters required to avoid solute depletion and segregation within an Al-Li alloy. The objective of this study is to develop the welding parameters required to avoid lithium depletion and segregation. In the present study weldments were produced via CSC-MIG process, using Al-Li 2199 sheet samples as the filler material. The residual lithium concentration within the weldments was then determined via Atomic Absorption (AA) and X-ray Photoelectron Spectroscopy (XPS). The microstructure was analyzed using High Resolution Scanning Electron Microscopy (HR-SEM). Finally the mechanical properties of welded samples were determined through the application of hardness and tensile testing.
Variation of Aging Behaviour for TM-Addition Al-Mg-Si Alloys
Authors: Wang Shu Mei , Matsuda Kenji , Kawabata Tokimasa , Ikeno Susumu
Published: December 2011

The transition metals such as chromium and manganese are usually added to 6000 series Al-Mg-Si alloys to control recrystallization and grain size and thus the properties of alloys. In Cr/Mn-addition alloys, Cr or Mn will expense Si to form the dispersoids as AlMnSi or AlCrSi and tend to decrease its aging effect. The aim of this work is to investigate the effect of transition metals (TMs) addition on the hardness and the microstructural features of Al-Mg-Si alloys. Al-Mg-Si alloys, which can be remarked as the quasi-binary alloys of Al-Mg2Si, are prepared with Cr or Mn addition by laboratory casting. Some other transition metals, such as Co and Ni, are also added to Al-Mg-Si alloys. The grain size of four alloys decreases with TMs addition, which consequently increases the as-quenched hardness of the alloys comparing with that of the Al-Mg2Si alloy without TMs addition. The difference between Cr/Mn-addition alloy and Co/Ni-addition alloy is that the dispersoids are formed in Co/Ni-addition alloy without expensing Si. Therefore, there is little effect on the aging effect of Si in Co/Ni-addition alloy. Keywords: transition metals, hardness, microstructural, Al-Mg2Si, dispersoids.
Behavior of Hydrogen Invasion in Aluminum Alloys from Different Environments
Authors: Watakabe Takahito , Itoh Goroh , Hatano Yuji
Published: December 2011

Hydrogen embrittlement has been known to occur by invading hydrogen (environmental hydrogen) in some metallic materials under several certain conditions, although the cause has not been clarified yet. To clarify the cause, investigations on the behavior of environmental hydrogen in metallic materials are needed. It has been reported that environmental hydrogen invades 7075 aluminum alloy through the second-phase particles (Al7Cu2Fe). However it has not been clarified yet whether environmental hydrogen invades aluminum through the interface between the matrix and second-phase or through the bulk of second-phase particles. In this study, tritium autoradiography technique, TARG, has been applied to an aluminum alloy containing a single kind of second-phase particles (Al7Cu2Fe), to elucidate the invasion behavior of hydrogen from two different environments: tritiated water and tritium gas. In TARG, hydrogen (tritium) atoms that stay in the vicinity of the surface can be detected as silver particles. Silver particles (hydrogen atoms) were primarily detected on the interface between the matrix and second-phase. Thus most of the invading hydrogen is concluded to be trapped by the interface.
A Study on the Dynamic Mechanical Properties of Silk Fibre Composites
Authors: Ho Mei Po , Wang Hao , Ho Chun Kit , Lau Kin Tak
Published: December 2011

Silk fibre has been popularly used for bio-medical engineering and surgically-operational applications because of its biocompatible and bio-resorbable properties for centuries. Using silk fibre as reinforcement for some bio-polymers to enhance the stiffness of scaffolding and bone implant plates has been developed. However, its dynamic mechanical properties with the biodegradable properties have not yet well understood. In this paper, the dynamic mechanical and thermal properties of degraded and non-degraded silk fibre reinforced Polylactic acid (PLA) composites are discussed.
Grading of Biofibres for Use in Natural Fibre Composites
Authors: Crosky A. , Loo Mindy , Zakaria Mohd , Parmar Paresh , Beehag Andrew , Leong Kok Hoong
Published: December 2011

Natural fibres obtained from plant sources are attractive as a replacement for glass fibres in fibre reinforced plastic composites because of their environmental benefits. However, unlike synthetic fibres, natural plant fibres show considerable variability in their mechanical properties due to the effects of climate, soil quality, time of harvest, etc. Variability in properties of the fibres translates into variability in the properties of products made from natural fibre composites and this is a major obstacle to the more widespread use of these materials. One way to accommodate fibre variability would be to test the mechanical behaviour of samples from incoming batches of fibres and assign a grade to each batch, which could then be taken into account when the fibres are subsequently used to produce composite products. However, conventional methods of determining mechanical behaviour require test samples of constant cross-sectional area but, unfortunately, this is not the case for natural fibres which vary in shape, width and lumen size, from place to place along the fibre. Insight as to how to deal with such variability is provided from the textiles industry where strength is determined as a function of linear mass density rather than cross-sectional area. This paper examines the feasibility of using a similar approach for grading natural fibres for use in natural fibre composite products.
Effect of Cryogenically Treated Electrode during AEDM of Nickel Based Super Alloy 718 for Surface Quality Improvement
Authors: Kumar Anil , Maheshwari S. , Sharma C.
Published: December 2011

In this experimental study attempt has been made to realize potential of cryogenic treatment in enhancing surface quality with fine aluminum and graphite additives powders in AEDM of nickel based super alloy Inconel 718. L36(23x36) Orthogonal Array has been selected to conduct and analyze experiments based on Taguchi methodology. Polarity, peak current, pulse on time, duty cycle, gap voltage, retract distance, concentration of fine aluminum and graphite powder added into the dielectric fluid are chosen as input process variables to study performance in terms of surface roughness (SR) using copper and deep cryogenically treated copper electrode. It is found experimentally that deep cryogenically treated copper electrode with addition of 6g/l graphite powder improves surface roughness appreciably. The same has been supported by SEM analysis of the machined surface.
Structural Evolution of Manganese Oxides via Surfactant-Free Solvothermal Routes
Authors: Zhang Yu Liang , Wang Wen Hua , Zhang Fu Hua , An Yan , Liu Tao , Yin Yan Sheng , Dong Li Hua
Published: December 2011

The preparation of γ-MnOOH nanorod and Mn3O4nanooctahedra have been achieved via hydrothermal reaction between KMnO4and DMF in water without the use of any surfactant or template. Various measurements were used to characterize the structure, morphology and electrochemical behavior of the resultant products. A possible growth mechanism has been proposed, the reaction temperature and the concentration of DMF plays a crucial role in the formation of the products. Their electrochemical properties have also been discussed.
Burr Size Reduction in Drilling of Al/SiC Metal Matrix Composite by Ultrasonic Assistance
Authors: Kadivar M.A. , Yousefi R. , Akbari J. , Rahi A. , Nikouei Sayed Mohamad
Published: December 2011

Metal matrix composites (MMCs) have received considerable attention due to their excellent engineering properties. Accuracy and surface finish play an important role in modern industry. Undesired projections of materials, known as burrs, reduce the part quality and negatively affect the assembly process. In this study, reducing burr size in drilling of MMC is performed by adding ultrasonic vibration to the process. Al/SiCp MMC with 5 wt% of SiC particulates in dry drilling operation with HSS drill tools coated with TiN was investigated. The effect of ultrasonic assistance on burr size was studied. The results demonstrate that under suitable ultrasonic vibration conditions, in comparison with the conventional drilling, the burr height and width could be reduced.
Formability Evaluation of FSW Blanks Made of Aluminum Sheet: Influence of Welding Speed and Tool Rotation Speed
Authors: Janaki Ramulu P. , Ganesh Narayanan R. , Kailash Satish V. , Reddy Jayachandra
Published: December 2011

The main aim of the work is to analyze the influence of welding speed and tool rotation speed on the forming behavior of FSW blanks. The FSW blanks are made of 6061 Al sheet of 2.1 mm thickness. The welded sheets are made at two different optimized levels of welding speed (90 and 100mm/min) and tool rotation speed (1300 and 1400 rpm). The effect of FSW parameters on the forming limit curve (FLC) and thickness distribution was analyzed by performing limit dome height (LDH) tests at few pre-defined stretching strain paths. It is observed that FSW blanks exhibit more formability as compared to un-welded sheets. The forming limit is found to improve with increase in tool rotation speed and it decreases with increase in welding speed. An attempt has been made to relate the thinning gradient developed during necking with the forming limit at different welding conditions.
Flexural Properties of Epoxy Composites Filled with Glass Powder: Preliminary Results
Authors: Ku Harry , Wong Peter , Huang J. , Fung H. , Trada Mohan
Published: December 2011

Epoxy resin was filled with glass powder with a view to increasing strength of the composite for structural applications by a research Centre on composites, University of Southern Queensland (USQ). In order to reduce costs, the Centre wishes to fill as much glass powder as possible subject to maintaining sufficient strength of the composites in structural applications. This project varies the percentage by weight of the glass powder in the composites which are then subjected to flexural tests. The results show that composite with 25 % by weight of the glass powder produces the highest flexural strength and Young’s modulus combined with a reasonable fluidity for casting; the highest flexural strain was achieved when the percentage by weight of glass powder is 10 %.
Reaction Injection Molding Process and Fireproof Property of Phenolic Foam Sandwich Panel
Authors: Li Xiao Feng , Lau Kin Tak , Yin Yan Sheng , An Yan , Shen Shi Shan , Zhang Fu Hua , Zhou Yun , Zhang Ying Jie
Published: December 2011

Reaction injection molding process of phenolic foam sandwich plate was introduced in order to resolve the difficulties in repetitive continuous manufacturing process of such product. The phenolic foam produced here have uniform pore diameter, good fireproof property and there need not any glue between phenolic foam and color steel plate which could make it a potential building material instead of polysterol sandwich plate.
Spandex Fiber Reinforced Shape Memory Polymer Composites and their Mechanical Properties
Authors: Sun Jian , Xu Yan Yi , Chen Yi Jin , Liu Yan Ju , Leng Jin Song
Published: December 2011

In this current study, spandex fiber with high elasticity and high recovery ratio were added into shape memory epoxy resin. Compared with pure shape memory resin, the Young’s modulus increases by 28.2%, tensile stress by 49.7% and fracture strain by 16.4% in samples with 20 vol% spandex fiber, while recover time reduces by 36s in samples with 40 vol% spandex fiber.
Poly(lactic acid)/Poly(butylene adipate-co-terephthalate) Blend and its Composite: Effect of Maleic Anhydride Grafted Poly(lactic acid) as a Compatibilizer
Authors: Teamsinsungvon Arpaporn , Ruksakulpiwat Yupaporn , Jarukumjorn Kasama
Published: December 2011

Poly (lactic acid) (PLA)/poly (butylene adipate-co-terephthalate) (PBAT) blend and its composite were prepared by melt blending method. Maleic anhydride grafted PLA (PLA-g-MA) prepared in-house was used as a compatibilizer to enhance the interfacial adhesion between PLA and PBAT and also to improve the dispersion of calcium carbonate (CaCO3) in polymer matrices. Increasing PBAT content (10-30 wt%) resulted in the improvement of elongation at break and impact strength of PLA. Tensile strength, Young’s modulus, and impact strength of PLA/PBAT blend improved with the presence of PLA-g-MA due to enhanced interfacial adhesion between PLA and PBAT. As CaCO3 (5 wt%) was incorporated into the compatibilized blend, tensile strength, Young’s modulus, and impact strength insignificantly changed while elongation at break decreased.
Effect of Wood Flour on Structural and Thermal Properties and Antibacterial Activity of PLA Filled with Triclosan
Authors: Prapruddivongs Chana , Sombatsompop Narongrit
Published: December 2011

Poly (lactic acid) (PLA) were compounded with wood flour and triclosan. The wood/PLA composites were then characterized using differential scanning calorimeter (DSC) and the antibacterial activity was also assessed via plate count agar (PCA) under a wide range of contact times usingEscherichia coli (E.coli) as the testing bacteria. The characterization results suggested that the addition of wood flour produced two melting peaks behaviour which resulted in an enlargement of degree of crystallinity (Xc) in the wood/PLA composites. These two metling peaks were probably related with re-crystallization of the PLA by the presence of wood. The antibacterial efficiency of triclosan/PLA was improved considerably by the presence of wood flour, suggesting that the wood particles could act as “anti-bacterial promoter” for the PLA.
Physical Properties of Rice Husk Fiber/Natural Rubber Composites
Authors: Srisuwan Ladawan , Jarukumjorn Kasama , Suppakarn Nitinat
Published: December 2011

In this study, rice husk fiber (RHF) was used as a reinforcing filler for natural rubber (NR). NR composites were prepared at various RHF contents, i.e., 10, 20, 30, 40 and 50 phr. Sulfur conventional vulcanization was used. Effect of RHF content on cure characteristics, mechanical properties and morphological properties of NR composites were investigated. The results showed that scorch and cure times of RHF/NR composites were not affected by increasing RHF content. Crosslink density, tensile strength, elongation at break and tear strength of NR composites slightly decreased with increasing RHF content whereas M100 and M300 of the composites slightly increased with increasing RHF content.
Experimental Study of Property of Magnetic Nanoparticle Prepared in Different Temperatures
Authors: Wang Fan , Li De Cai , Zhang Meng , Zhang Zhi Li
Published: December 2011

For prepare magnetic liquids with good property, the authors prepared Magnetic Fe3O4 nanoparticles by co-precipitation in different temperatures including 60°C, 70°C, 80°C in this experiment and analyzed the product of Magnetic Fe3O4 nanoparticles by X-ray Diffraction Analysis, Transmission Electron Scanning, Saturation Magnetization Test and the result indicate that Magnetic Fe3O4 nanoparticles prepared at 70°C have good crystallinity and high saturation magnetization and suitable for prepare magnetic liquid.
Preparing Fluorhydroxyapatite by Aqueous Precipitation Method
Authors: Zhu Qing Xia , Jiang Wei Hui , Wang Hong Da , Shao Chuan
Published: December 2011

The nanosized fluorhydroxyapatite (FHA) had been synthesized by aqueous precipitation method. The effects of synthesis temperature,fluoride ion concentration and pH value on the fluoride substitution were investigated.The phase composition and the change of crystal structure were characterized by X-ray diffraction and fourier transform infrared spectroscopy. The results show that crystal lattice parameters and bond energy make changes by incorporation of F in the structure.The size of FHA crystals increase as the precipitation temperature. The phase composition of FHA is mainly controlled by the pH value.
Porous Silicon Nitride Prepared by Cold Isostatic Pressure
Authors: Gao Fang , Liu Jian , Wang Chong Hai
Published: December 2011

Porous silicon nitride with pore forming agent of starch were prepared by cold isostatic pressing, forming problem of complex shapes were solved by methods of carbonization of starch and decreasing forming pressure. Products of porous silicon nitride had the performance parameter with density 1.5g/cm3, porosity over 55%, bending strength over 100 MPa.
Fabrication of Aluminium Nitride by Electrophoretic Deposition
Authors: Zhang Hai Long , Li Jun , Zhou Guo Hong , Wang Shi Wei
Published: December 2011

The electrophoretic deposition (EPD) technique has been developed to prepare AlN ceramics and the topic of this paper was the investigation of the AlN ceramic suspensions for electrophoretic deposition. The only addition of triethylamine didn’t promote the hydrolysis of AlN powder in 95% ethanol. The absorption of the polyacrylic acid (PAA) resulted in an increased Zeta potential, indicating that PAA is a very effective dispersant for the AlN and Y2O3 powders. Furthermore, by adding a combination of PAA and triethylamine, an stable AlN suspension could be obtained which was necessary for realising a high packing density in the electrophoretically deposited green bodies. The conductivity measurements indicated that suspension conductivity was lower than liquid conductivity. The lower conductivities of the suspensions could be explained by the fact that in concentrated suspensions the free ionic species are hindered in their movement by the particles. The conductivity of the centrifugate was higher than that of the suspension. It can be concluded that during the EPD the current in the suspension is mainly carried by the free ionic species. The transport of positively charged ionic species to the upper electrode (cathode) was slower than their consumption by the electrode reaction, an increased concentration overvoltage caused a significant increase in total electrical resistance due to the higher potential drop at the cathode. Finally, the EPD was usually stopped according to the increase in potential drop.
Preparation and Performance Characterization of Active Coal Gangue Powder (ACGP) Used for Cement Admixture
Authors: Yu Xin Gang , Hu Hong Chao , Huang Hai Ke , Zhang Yi , Li De Jun
Published: December 2011

Two kinds of high active coal gangue powder (ACGP) were prepared by heat treated and ball milled coal gangue. The density, fineness, Loss on ignition (LOI), activity and influence of the fineness of the two kinds of ACGP on the density and I/W (compressive strength to weight of the foam concrete specimens) of foam concrete were also studied in this paper. The results show that the density and I/W of the foam concrete were greatly affected by the fineness of ACGP. The finer of the ACGP, the lower density and higher I/W of the coal gangue foam concrete will be got. Based on the experimental results, a method to evaluate the activity of active powder used for cement admixture is proposed and the activity of the ACGP is also evaluated.
Synthesis, Characterization and Optical Property of Uniform Bi2S3 Nanorods
Authors: Liu Shu Ling , Shi Qiang Qiang , Tong Jian Bo , Li Shu , Liu Miao Miao
Published: December 2011

Uniform rod-like Bi2S3 nanostructures were successfully synthesized by a simple hydrothermal process in a high yield. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and UV-vis absorption spectroscopy were used to characterize the obtained products. It was found that the morphologies of the as-obtained Bi2S3 were highly dependent on the experimental parameters, including the pH value and the solvent. The adjustments of two parameters could lead to an obvious shape evolution of products. Then based on the discussion of the experimental parameters and the captive intermediate, the possible growth mechanism was proposed.
RF Plasma Synthesis of Nickel Nanoparticles from Liquid Precursor
Authors: Bai Liu Yang , Yuan Fang Li , Zhang Hai Bao , Li Jin Lin
Published: December 2011

Nickel nanoparticles were synthesized from liquid precursor via H-plasma reduction route. XRD patterns revealed that pure metallic nickel powders could be obtained when nickel ammine complex aqueous solution was used as precursor. FESEM showed that the products are composed of well-dispersed nanospheres with an average diameter less than 100 nm. The tap density is about 3.85g/cm3, and the sheet resistance of the conductive film prepared using the nickel particles is about 58mΩ.
Interaction between Hydroxyapatite and Collagen
Authors: Huang Zhao Long , Liu Gui Yang , He Ying , Yi Zhong Zhou , Guo Jun Ming
Published: December 2011

To study the interaction between hydroxyapatite (HAP) and collagen in bone, we researched the phenomenon of collagen biomineralization and self-assembly in viro by uv-vis spectra and circular dichroism (CD) spectra. The materials prepared by self-assembly collagen and collagen-HAP showed layer structures. And the product prepared by collagen-HAP had better and more compact appearance. The decrease of speed of collagen self-assembly was caused by calcium ion or strontium ion added. The trough of CD spectra moved down in calcium-containing solution and moved up when forming precipitation of calcium phosphate from the solution. It indicated that the effect of collagen self-assembly was caused by calcium ions, strontium ions etc. in the solution. The IR spectrum proved that a coordinate bond formed between calcium ion and amide groups on collagen.
Thermodynamic Analysis of Doped Titanium Dioxide Powders by Coprecipitation-Coating Process
Authors: Yang Chen Jing , Du Jing Hong , Gan Guo You , Yan Ji Kang , Zhang Jia Min , Yi Jian Hong
Published: December 2011

On the basis of the mechanism of ions precipitation reaction equilibrium, the thermodynamic analysis of Men+(La3+, Ni2+, Fe3+, Al3+)-CO32--NH3•H2O system was discussed in this paper. The relation curves between total concentrations of each metal ion and pH values at different total ammonia concentrations cN and total carbon concentrations cC were obtained. The suitable pH value of the complete precipitation reaction for all metal ions was also determined. It shows that when cN = 0.010 mol•L-1 and cC = 1.000 mol•L-1, the optimal pH is 9.0 to prepare the doped titanium dioxide powders by coprecipitation-coating process and using NaHCO3 and NH3•H2O as the precipitants.