bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of Artificial Bone by the Combination of Electrospinning, Extrusion and Slurry Processes
Authors: Nguyen Thi Hiep , Lee Byong Taek
Published: June 2010

In this work, we focused on the manufacture of artificial bone for medical replacement based on the combination of individual properties of ceramic and polymer. Here, periosteum was fabricated with a HAp (Hydroxylapatite) frame, while compact bone was fabricated from multi-layer electro-spun PS (polystyrene)/PCL (polycaprolactone) using biocompatible collagen glue. Spongy bone is formed from PCL/PLGA spongy loading BCP (Biphasic Calcium Phosphate) powder coated collagen. SEM images showed successful fabrication of the artificial bone scaffold through a combination of electro-spinning, extrusion, and use of the slurry method.
Quantity and Quality of Regenerated Bone in Grooves Aligned at Different Angles from the Implant Surface
Authors: Noyama Yoshihiro , Ishimoto Takuya , Kuramoto Koichi , Sakai Takashi , Yoshikawa Hideki , Nakano Takayoshi
Published: June 2010

The quantity and quality of regenerated bone strongly depends on the direction and amplitude of in vivo principal stress; therefore, in vivo stress distribution near bone implants should be optimized on the basis of the morphology of the interface between an implant and bone tissue. In this study, grooves were created on the implant surface in order to improve the surface morphology of the implant for optimizing in vivo stress distribution near the implant. The preferential alignment of the biological apatite (BAp) c-axis, which is a parameter of bone quality and controls the mechanical function of bones, is closely related to stress distribution; therefore, the direction of principal stress should be matched with the direction of the groove on the implant surface. Hip implants were prepared with grooves aligned at different angles from the surface; the grooves were located on the stem portion. These implants were inserted in a beagle femur to investigate the dependency of the quantity and quality of newly formed bone in the grooves on the groove angle. The degree of preferential alignment of the BAp c-axis of the regenerated bone in the grooves strongly depends on the angle of the groove to the principal stress vector that was estimated previously to an animal experiment. The regenerated bone forms anisotropic BAp orientation in response to the principal stress in the grooves; therefore, the direction of the grooves has to be designed on the basis of the stress distribution near the implant.
The Study of Cotton Finishing by Artemsia Argyi Oil Microcapsules
Authors: He Guan Ru , Li Ly , Au Wai Man , Wong Thomas K.S. , Yang Zhuo Hong , Jiang Qiong Ling
Published: June 2010

In this paper, gelatin-arabic gum microcapsules containing Artemsia argyi oil was prepared by complex coacervation firstly, along with its application to textile finishing using 2D resin as a crosslinking reagent was investigated. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to investigate the formation of ether bonds between 2D resin and cellulose and/ or gelatin-arabic gum microcapsules. The washing durability, strength retention, wrinkle-free performance, formaldehyde content, release property and antibacterial property of the finished fabrics were also tested. The results showed that the crease recovery angle of finished fabric was above300°, with the strength retention was above 60% and the released formaldehyde concentration was lower than 75 mg/kg. While the released amount of Artemsia argyi oil was less than 50% after 9 days. Moreover more than 70% antibacterial property could also be obtained even after 30 washing cycles.
Electrochemical Synthesis of Sensitive Layer of Polyaniline: Effects of Acid Doping on Ethylene Gas Sensing
Authors: Pattananuwat Prasit , Aht-Ong Duangdao
Published: June 2010

Ethylene gas is released from plants as a hormone during a certain stage of life cycle and induces ripeness in fruits and blooming of flowers. The early detection and control amount of ethylene gas in storage can prevent wastage of the entire stock. The aims of this research were to fabricate ethylene sensor based on polyaniline (PANi) and to investigate the effect of acid doping on an improvement of its sensitivity. Electrochemically synthesized conductive layer of PANi was prepared via an in situ radical polymerization by repeating potential cycling in the range of -0.3 to 1.0 V relative to the silver reference electrode and platinum counter electrode. The PANi films were deposited on interdigitated electrode of gold substrate. These emeraldine bases of PANi were doped with five different acids doping (such as HCl, H2SO4, H3PO4, TSA, and DBSA) at particular concentration. The influences of types and amount of acid on the sensitivity of acid doping PANi on ethylene gas were investigated. The PANi-dope films were characterized by Fourier transform infrared spectroscopy (FT-IR) and UV-visible spectroscopy (UV-vis). The morphology of PANi film was investigated by scanning electron microscope (SEM). The magnitude sensing of doping PANi in terms of types and amount of acid against ethylene gas was presented.
Introduction
Precipitation Behavior and Magnetic Properties of Nano–Scale Particles in a Cu–Fe–Ni Alloy
Authors: Kang Sung , Takeda Mahoto , Hiroi Zenji , Takeguchi Masaki
Published: June 2010

The precipitation behavior of nano–scale magnetic particles formed in a Cu–Fe–Ni alloy on isothermal annealing at 873K and 1073K have been investigated by means of transmission electron microscopy (TEM). Nano–scale magnetic particles were formed randomly in the Cu–rich matrix after receiving a short annealing due to phase decomposition in the alloy. With increasing the isothermal annealing time, however, the striking features that two or more nano–scale particles with a cubic shape and precipitates with a needle shape were aligned linearly along <100> directions were observed on isothermal annealing at 873K and 1073K, respectively. To investigate the relationship between microstructures and magnetic properties of precipitates in a Cu–Fe–Ni alloy were also carried out the superconducting quantum interference device (SQUID) magnetometer. The present study revealed that several significant influences to magnetic properties were induced during the precipitation process in this alloy.
Grain Boundary Engineering and Alterations in Anisotropy of Interfacial Properties
Authors: Lejček Pavel , Gärtnerová Viera , Jäger Aleš
Published: June 2010

Literature data on grain boundary properties show surprisingly in some cases reversed courses of the structural dependences than expected, or directly prove their qualitative changes with changing temperature. This “reversed anisotropy” is demonstrated for example of grain boundary segregation. It is shown that this reversed anisotropy of grain boundary properties can be explained by the enthalpy–entropy compensation effect. Serious consequences of altered structural dependence of grain boundary properties for Grain Boundary Engineering are discussed.
Ultrafine Grained High Strength Low Alloy Steel with High Strength and High Ductility
Authors: Shi Jie , Cao Wen Quan , Dong Han
Published: June 2010

In this study a C-Mn High Strength Low Alloy steel (HSLAs) was processed by quenching and austenite reverted transformation during annealing (ART-annealing), which results in an ultrafine grained duplex microstructure characterized by scanning electron microscopy equipped with electron back scattered diffraction, transmission electron microscopy and x-rays diffraction (SEM/EBSD, TEM and XRD). Microstructural observation revealed that the full hard martensitic microstucture gradually transformed into ultrafine grained duplex structure with austenite volume fraction up to 30% at specific annealing conditions. Mechanical properties of this processed steel measured by uniaxial tensile testing demonstrated that an excellent combination of strength (Rm~1GPa) and total elongation (A5~40%) at 30% metastable austenite condition in studied C-Mn-HSLAs. This substantially improved strength and ductility were attributed to the strain induced phase transformation of retained austenite dispersed throughout the ultrafine grained microstructure. At last it is proposed that ART-annealing is a promising way to produce high strength and high ductility steel products.
Shape-Controlled Syntheses of Silver Nanoparticles: Role of the Seeds
Authors: Chen Chu Yang , Jiang Xu Chuan , Xiong Shi Xian , Yu Ai Bing
Published: June 2010

Precious metallic nanoparticles have attracted considerable attention because of their unique properties (optical, electronic, and chemical properties) and potential applications in many areas such as optical probes, biochemical sensors, and surface enhanced Raman Spectrum. Despite many successes in synthesis of anisotropic nanoparticles (rods, plates), some limitations still exist in generating monodispersed silver nanoparticles. This study intends to elucidate the influence of crystalline seeds on the shape, size, and size distribution of nanoparticles through a seed-mediated method. The crystalline seeds can be modified by using different ways, such as heating treatment and oxidative etching. The shape and size of the generated particles will be characterized by TEM, and the particle formation and growth is tracked by UV-vis spectrometry. The findings would be useful for the shape-controlled synthesis of metal nanoparticles for desired functional properties.
Structural Characterization of Electrodeposited Nickel-Iron Alloy Films
Authors: Marita Yusrini , Yaacob Iskandar Idris
Published: June 2010

Nickel-iron nanocrystalline alloy films were prepared on copper substrates by electrochemical deposition at various current densities of 6, 9.7, 11.5 and 15.2 A dm-2. X-ray diffraction measurements confirmed that all nickel-iron alloy films formed have face-centered cubic structure. The structural parameters such as the lattice constant, crystallite size, microstrain and dislocation density were determined for the nickel-iron alloy films. The crystallite size of the films reduced from 17 to 12.9 nm when the current densities were decreased. The reduction in crystallite size increased the dislocation density. Magnetic property measurements using alternating gradient magnetometer indicated that these alloys were ferromagnetic. The saturation magnetization Ms of nickel-iron alloy films increased with decreasing deposition current density, which was attributed to the increase of iron content. Nickel-iron alloy film prepared at deposition current density of 6 A dm-2 showed the maximum value of Ms. The coercivity of nickel-iron alloy films increased with decreasing current density, which was likely caused by reduction in crystallite size.
Testing of Aluminium Carbide Formation in Hall-Heroult Electrolytic Cell
Authors: Pietrzyk Stanislaw , Palimaka Piotr
Published: June 2010

The trend in the aluminium smelting industry today is to operate cells with graphitized carbon cathode linings, increased current density and acidic bath chemistry. The resulting problem is an accelerated wear of graphitized cathode blocks, thought to be caused by formation and subsequent dissolution of Al4C3 at the cathode lining surface. The cycle of formation and subsequent dissolution Al4C3 is recognized as one of the most important mechanism causing pothole and surface wear, which results in limiting of the cell lifetime and loss efficiency. A special laboratory test method was developed to elucidate the mechanism of Al4C3 formation in electrolytic cell. The Al4C3 formation in the region between the carbon surface and aluminium as well as between the carbon surface and electrolytic bath has also been studied using X-ray diffraction, as well as optical and scanning electron microscopy. Solid Al4C3 layer was observed at the carbon surface. A possible mechanism which explains the presence of Al4C3 at the metal-bath interface is the transfer of dissolved carbide in the bath from metal-carbon interface.
Thermodynamic Evaluation of the Fe-Pr Binary System
Authors: Zhou Guo Jun , Zeng De Chang
Published: June 2010

The Fe–Pr binary system was thermodynamic evaluation by means of the CALPHAD method based on phase diagram experimental data from the literature and a few values of the mixing enthalpy in the liquid phase obtained by the Miedema theory technique. Each of the selected data values is given a certain weight, which is chosen and adjusted based on the thermodynamic data and diagram phase data. A consistent thermodynamic description of the Fe–Pr binary system is presented: only one intermediate compound, Fe17Pr2, is stable in the system and forms peritectically at 1371K. An eutectic reaction L↔Pr+ Fe17Pr2 occurs at 939K and the eutectic liquid contains 82 at% Pr, five solid solution phases (Fe-rich αFe, γFe and δFe, Pr-rich αPr and βPr) and the liquid solution phase were considered in the evaluation. The intermediate phase was treated as stoichiometric compound, the solid solutions as ideal and the liquid solution phase by the Redlich–Kister formalism. The calculated phase diagram and thermodynamic properties are in good agreement with available experimental data.
Structural Characteristics of Pultruded FRP Composite Experienced Freezing and Thawing Cyclic Temperature
Authors: Kim Jae Wook , Shin Kwang Yeoul , Ok Dong Min , An Dong Jun , Yoon Soon Jong
Published: June 2010

Due to the advantages of FRP composite such as corrosion resistance, light weight, high specific strength and stiffness, flexibility, etc., the use of FRP composite in construction sites is increasing steadily. Especially, high corrosion resistance is a very strong point of FRP composite. Although the FRP composite has many advantages, the material properties of FRP composite under various environmental conditions at the construction sites are not well investigated. In this paper, we present the results of experimental investigations of FRP composite experiencing freezing and thawing cyclic temperature. In this investigation, we performed experimental studies to find the stress versus strain characteristics of FRP composite experiencing freezing and thawing cyclic temperature variation. In the experimental program, strength and stiffness of the pultruded FRP composite specimens under uniaxial tension affected by the freezing and thawing temperature change mechanism are evaluated and the results are discussed.
The Laser Surface Remelting of Austenitic Stainless Steel
Authors: Brytan Zbigniew , Bonek Mirosław , Dobrzański Leszek Adam , Ugues Daniele , Grande Marco Actis
Published: June 2010

The laser surface remelting (LSR) process was successfully applied to restore localized corrosion resistance in sensitized stainless steel and also as a useful method to improve passivity of some martensitic stainless steels. The LSR process can be successfully applied to repair cracks and defects at the surface of highly thermo-mechanically loaded parts of stainless steel. The purpose of presented study was to evaluate the microstructure and properties of laser remelted surface of stainless steels. The wrought austenitic stainless steel and sintered in vacuum 316L type were studied. The laser treatment was performed with the use of high power diode laser (HPDL) and the influence of beam power of 0.7-2.1kW on the properties of the surface layer was evaluated. The geometrical characteristics and x-ray analysis of weld bead were studied as well as microhardness, surface roughness and corrosion resistance were measured. The increase of laser beam power of LSR resulted in the increase of hardness of sintered stainless steel due to the reduction of porosity and formation of fine dendritic and cellular-dendritic microstructure. The corrosion resistance of remelted surface increased for sintered materials, when remelted at 2.1kW. The wrought stainless steel revealed impairment of pitting corrosion when remelted at lower beam power rate.
Design of Pre-Weakening and Evaluation of Structural Safety for Explosive Demolition of Concrete Silo
Authors: Park So Young , Choi Hoon , Baek Seung Cheol , Kim Hyo Jin , Yoon Soon Jong
Published: June 2010

Recently the demand for demolition of unnecessary cylindrical silo structure is increasing due to the deterioration and malfunctional conditions and the issue of demolition is in the limelight. To minimize environmental hazards caused during the process of demolition, the explosive demolition method has been applied increasingly. The concrete silo structure is often built by the slip-form method which is a continuous concrete casting operation. As a result, the structure does not have expansion joints or other structural weaknesses that can be used to assist in the demolition process. This study presents the pre-weakening of explosive demolition of the cylindrical concrete silo structure by overturning method. Pre-weakening for the explosive demolition of the structure is usually conducted based on the field experience without technical guideline for the pre-weakening procedure. Hence, there always exist safety-related concerns. To demolish the structure by blast effectively and safely, rational approach to the pre-weakening and evaluation method of the load carrying capacity of the pre-weakened structure should be established. To do this, mechanical properties of concrete are estimated by experiment prior to structural analysis. Based on the result of investigation, design or operation methods of pre-weakening for the blast demolition are discussed.
Mechanical Properties of 5083 Aluminium Welds after Manual and Automatic Pulsed Gas Metal Arc Welding Using E5356 Filler
Authors: Mutombo Kalenda , du Toit Madeleine
Published: June 2010

Semi-automatic and automatic pulsed gas metal arc welding (GMAW) of aluminium alloy 5083 with ER5356 filler wire causes considerable softening in the weld. The tensile strength of dressed automatic welds approaches that of the base metal, but the stress concentration caused by the weld toe in undressed semi-automatic welds reduced the tensile strength significantly. Fully automatic welds displayed improved fatigue properties compared to semi-automatic welds.
A Study on Improvement of Fatigue Life for Woven Glass Fabric/Epoxy Laminate Composite Applied to Railway Vehicle
Authors: Ko Hee Young , Shin Kwang Bok , Kim Jung Seok
Published: June 2010

In this study, the fatigue characteristics and life of woven glass fabric/epoxy laminate composites applied to railway vehicle were evaluated. The fatigue test was conducted by tension-tension load with stress ratio R of 0.1 and frequency of 5Hz. The material used to fatigue test was two types of woven glass fabric/epoxy laminate composite with and without the reinforcement of carbon/epoxy ply. Also, the fatigue life of woven glass fabric/epoxy laminate composite was compared with that of aluminum 6005 used to the car-body and under-frame structures of railway vehicle. The test results showed that the failure strength and life of woven glass fabric/epoxy laminate composite with the reinforcement of three carbon/epoxy plies had a remarkable improvement in comparison with that of bare specimen without reinforcement.
Preliminary Review of Physically Based Methodologies for Predicting the Strength of Visibly Damaged Composite Laminates
Authors: Harman Alex , Litchfield Andrew , Thomson Rodney
Published: June 2010

Approaches to detect, assess, monitor and repair damage in critical aircraft components fabricated from composite materials are essential for safe and cost effective operation. In metallic aircraft structures, it is common to leave some fractures in situ for a prescribed period until it is convenient to repair, provided strict inspection and verification processes are in place. Under current military aircraft structural management guidelines, visible damage to critical composite components requires either immediate repair or replacement. Much has been learnt about the behaviour of damaged composite structures, but further investigation is required to develop validated residual strength and life prediction tools. A preliminary review of an early physically based, residual strength prediction method was conducted. The accuracy of this method for use in predicting the strength of composite following a complex damage was tested by comparing the results with compression-after-impact test data for a composite laminate representative of F/A 18 fracture critical structure.
The Indentation Behaviour of Carbon Fibre Composite Tubes-Experiments & Modelling
Authors: Sudharsan Ranjani , Rolfe Bernard F. , Hodgson Peter
Published: June 2010

Metallic tubes have been extensively studied for their crashworthiness as they closely resemble automotive crash rails. Recently, the demand to produce lighter weight, yet safer vehicles has led to the need to understand the crash behaviour of novel materials, such as fibre reinforced polymer composites, metallic foams and sandwich structures. This paper discusses the static indentation response of Carbon Fibre Reinforced Polymer (CFRP) tubes. The side impact on a CFRP tube involves various failure mechanisms. This paper highlights these mechanisms and compares the energy absorption of CFRP tubes with similar Aluminium tubes. The response of the CFRP tubes during bending was modelled using ABAQUS finite element software with a composite fabric material model. The material inputs were given based on standard tension and compression test results and the in-plane damage was defined based on cyclic shear tests. The failure modes and energy absorption observed during the tests were well represented by the finite element model.
Effect of N on Microstructure and Tensile Behavior of TWIP Steel
Authors: Lee Sang Won , Kim Jin Kyung , Kim Sung Kyu , Chin Kwang Geun , De Cooman Bruno C.
Published: June 2010

The present study focused on the design and testing of new 3rd generation TWIP steels to find reduced Mn content alternatives to the existing high Mn FeMnC and FeMnAlC alloy systems. In order to investigate the effect of nitrogen addition, 12Mn0.6C-N was examined and 18Mn0.6C-N steel was used as a reference. Effects of nitrogen and manganese on the microstructure and mechanical properties were investigated by X-ray diffraction, optical microscopy, scanning electron microscopy and tensile testing. The deformation microstructures of 12Mn0.6C-N were mixtures of twinned austenite and 5~10% ε-martensite. Only deformation twinning was observed in 18Mn0.6C-N during the deformation due to its higher stacking fault energy. 18Mn0.6C-N steel exhibited higher strength and elongation than 12Mn0.6C-N steel. The effect of the strain rate on the tensile behavior of both materials was also examined. While 18Mn0.6C-N showed clear negative strain rate sensitivity, 12Mn0.6C-N did not show a clear relationship between flow stress and strain rate. The effect of annealing temperature on the tensile behavior and microstructure was also examined.
Improvement of Mechanical Properties of Injection Molded Wood/Polypropylene Composites Parts with Ultrasonic Oscillation Assistant
Authors: Xie Lei , Grueneberg Timo , Steuernagel Leif , Ziegmann Gerhard , Militz Holger
Published: June 2010

Due to the water absorption of wood fillers and poor adhesion between wood fillers and polymer matrix, the loosen material structure always appears in wood/polymer composites after injection molding process, which results in reduced composites mechanical properties. In this study, two kinds of wood particles with different sizes and properties were compounded with Polypropylene (PP) in highly filled level (by 50% and 60% weight concentration). The experimental tensile test samples were prepared by one double-gate injection mould integrated an ultrasonic generator unit. The experiments were carried out for studying how the ultrasonic output power and the oscillation inducing time affect the injection molded wood/PP composites mechanical properties. 3 output power levels (400W, 600W and 800W) and 2 inducing mode were set (Mode1. the oscillation is induced from injecting moment to ejection moment; Mode2. the oscillation is induced from injecting moment to packing procedure finishing). The results show that the E module, tensile strength and density of the test parts are obviously changed with various ultrasonic output power and inducing time. Comparing the mechanical properties of parts with and without ultrasonic assistant indicates that the ultrasonic oscillation is a practical method to improve mechanical properties of injection molded wood/PP composites parts.
Form Factor for the Design of Pultruded FRP Structural Members under Compression
Authors: Choi Jin Woo , Lee Seung Sik , Joo Hyung Joong , Sim Young Jong , Yoon Soon Jong
Published: June 2010

As a new construction material, fiber reinforced polymeric plastic structural shapes are readily available. Therefore, construction and structure rehabilitation using FRP materials are an ever increasing trend because of FRP material’s superior chemical and mechanical properties compared with those of conventional construction materials such as steel and concrete. Among the FRP materials, pultruded fiber reinforced polymeric plastics are the most popular for civil engineering applications. However, it has relatively low modulus of elasticity and also cross-section of structural shapes is composed of plate components such as flange and web. Therefore, stability is an important issue in the design of pultruded structural shapes. For the design of pultruded structural member under compression, buckling and post-buckling strengths of plate components should be taken into account. In the structural steel design following AISC/ LRFD, this effect, in addition to the buckling strength, is incorporated with a form factor. In this research, the form factor for the design of pultruded structural shapes under compression is investigated. Based on the analytical study, the form factor for the design of pultruded structural shapes have been suggested.
Ballistic Performance of Zr-Based Bulk Metallic Glass/Ti Surface Composites Fabricated by High-Energy Electron-Beam Irradiation
Authors: Do Jeong Hyeon , Jeon Chang Woo , Nam Duk Hyun , Kim Choong Nyun Paul , Song Young Bum , Lee Sung Hak
Published: June 2010

This study aimed at investigating the ballistic performance of Zr-based bulk metallic glass/Ti surface composites fabricated by high-energy electron-beam irradiation. The ballistic impact test was conducted on surface composite plates to evaluate the ballistic performance. Since the surface composite layers were observed to block effectively a fast traveling projectile, while many cracks were formed in the composite layers, the surface composite plates were not perforated. The surface composite layer containing ductile β dendritic phases showed the better ballistic performance than the one without containing dendrites because dendritic phases could hinder the propagation of shear bands or cracks.
Anatase-Type Ti1-2xNbxAlxO2 Solid Solution/Silica (SiO2) Composite Nanoparticles: Synthesis, Phase Stability, and Photocatalytic Performance
Authors: Hirano Masanori , Kuno Norio
Published: June 2010

Composite nanoparticles (anatase-type Ti1-2XNbXAlXO2 solid solution/SiO2) were directly synthesized from precursor solutions in the presence of urea under mild hydrothermal conditions at 180 °C for 5 h. The crystallite size of anatase was gradually decreased with increased silica content in the composite nanoparticles formed under weakly basic hydrothermal conditions via the hydrolysis of urea. The composite nanoparticles with composition Ti0.9Nb0.05Al0.05O2/SiO2 = 100/10 mol% showed good photocatalytic activity. The anatase-to-rutile phase transformation in the course of heating in air was retarded to maintain the anatase-type structure up to more than 1050 °C without a trace of rutile phase by the formation of composite nanoparticles (Ti0.90Nb0.05Al0.05O2/SiO2 = 100/20 mol%) with amorphous silica.
Effect of TEOS Addition on Adhesion and Electrochromic Properties of Silica-Polyaniline Core-Shell Composite Films on ITO Glass
Authors: Kim Gyun Tak , Kim Hoh Yeong , Hwang Tae Jin , Lee Heung Yeol
Published: June 2010

The adhesion enhancement effect of tetraethoxysilane (TEOS) addition to a silica-polyaniline composite film on ITO glass substrate was studied. The composite film was prepared with the silica-polyaniline core-shell composite nanoparticles which were synthesized by a chemical polymerization of polyaniline in a colloidal solution of silica. A small amount of TEOS and acidic water was added to the dispersion solution of composite nanoparticles. The addition of TEOS was intended to increase the adhesion of electrochromic film to substrate without a deterioration of the electrochromic properties such as response time and cycle life. The adhesion of the films was tested by a tape test, and the composite film with TEOS showed a dramatic increase in adhesion to the ITO glass substrate when compared with the film deposited without TEOS. The electrochromic properties of the films were also characterized using the cyclic voltammetry and the optical response measurement.
On the Stretch-Flangeability of High Mn TWIP Steels
Authors: Chen Lei , Kim Jin Kyung , Kim Sung Kyu , Chin Kwang Geun , De Cooman Bruno C.
Published: June 2010

Edge stretching is an important formability issue when it comes to apply sheet steels to automotive industry. Anisotropy, strain hardening and toughness are closely related to hole expansion properties. In this paper, hole expansion properties of a high Mn fully austenitic Twinning Induced Plasticity (TWIP) steel are compared with three other types of single-phase sheet steels. The effects of r-value, n-value, m-value and post-uniform elongation on the edge stretch-flangeability are discussed. It was found that the post-uniform elongation and the strain rate sensitivity have a pronounced effect on hole expansion properties.
Broad-Band Vibro-Impacting Energy Harvester
Authors: Moss Scott D. , Powlesland Ian , Konak Michael , Barry Alex , Galea Steve C. , Carman Gregory
Published: June 2010

The certification of retro-fitted structural health monitoring (SHM) systems for use on aircraft raises a number of challenges. One critical issue is determining the optimal means of supplying power to these systems, given that access to the existing aircraft power-system is likely to be problematic. Other conventional options such as primary cells can be difficult to certify and would need periodic replacement, which in an aircraft context would pose a serious maintenance issue. Previously, the DSTO has shown that a structural-strain based energy harvesting approach can be used to power a device for SHM of aircraft structures. Acceleration-based energy harvesting from airframes is more demanding (than a strain based approach) since the vibration spectrum of an aircraft structure varies dynamically with flight conditions, and hence a frequency agile or (relatively) broad-band device is often required to maximize the energy harvested. This paper reports on the development of a prototype vibro-impacting energy harvester with a ~59 gram flying mass and two piezoelectric bimorph-stops. Over the frequency range 29-41 Hz using a continuous-sine 450 milli-g r.m.s. excitation, the harvester delivers an average of 5.1 mW. From a random band-passed 25-45 Hz excitation with r.m.s. 450 milli-g, the average harvester output is 1.7 mW.
A New Concept for Alloy Design of Nb-Based Hydrogen Permeable Alloys with High Hydrogen Permeability and Strong Resistance to Hydrogen Embrittlement
Authors: Yukawa Hiroshi , Morinaga Masahiko , Nambu Tomonori , Matsumoto Yoshihisa
Published: June 2010

A concept for alloy design of Nb-based hydrogen permeable alloys has been proposed based on the mechanical properties of niobium in hydrogen atmosphere and also on the hydrogen chemical potential in metal membrane. Following this concept, Nb-based alloys are designed and developed that possess excellent hydrogen permeability without showing any hydrogen embrittlement.
Hydrogen Storage Properties of Mg-Ni Alloy Catalysed by Multi-Walled Carbon Nanotubes
Authors: Aminorroaya Sima , Liu Hua Kun
Published: June 2010

The hydrogen storage performance of ball-milled sample of cast Mg-6 wt% Ni alloy was investigated. Morphology and microstructure of the cast sample and achieved powders were evaluated by high-resolution scanning electron microscopy. The activation characteristics of ball-milled alloy are compared with those of the materials obtained by ball-milling of 5 wt% multi-walled carbon nanotubes (MWCNTs) for 2 hours. MWCNTs enhanced the absorption kinetics considerably. The hydrogen content of modified powder by MWCNTs reached to the maximum hydrogen capacity within two minutes of exposure to hydrogen at 370°C and 2MPa pressure. The evidence is provided that nucleation and growth of hydrides accelerate drastically by homogenously distribution of MWCNTs on the surface of ball-milled powders.
Ultra Fine-Grained 6wt% Manganese TRIP Steel
Authors: Lee Sea Woong , Lee Kyoo Young , De Cooman Bruno C.
Published: June 2010

Ultra-fine grained TRIP steels (UFG-TRIP) containing 6wt%Mn were produced by intercritical annealing. An ultra-fine grained microstructure with a grain size less than 1μm was obtained. The formation mechanism of the high volume fraction of retained austenite was investigated by dilatometry, XRD and magnetic saturation. The fraction of retained austenite was strongly dependent on the annealing temperature. The tensile properties were also found to be strongly influenced by the annealing temperature with poorer mechanical properties being observed at higher annealing temperatures. It was found that the stabilization of the retained austenite was both a composition and size-effect, made possible by the grain refinement due to the reversely transformed martensite.
Resistance to Hydrogen Embrittlement and Behavior of Hydrogen in 6000 Series Aluminum Alloys
Authors: Itoh Goroh , Watanabe Masataka , Kuroyanagi Kazuya , Zhao Pi Zhi
Published: June 2010

In recent years, the fossil fuel exhaustion and global warming have become serious problems. As a way to solve these problems, the development of the fuel cell vehicles has been paid attention to. In the fuel cell vehicles, high-pressure hydrogen gas is stored in a container consisting of aluminum liner and surrounding fiber-reinforced plastic layer. To increase the mileage per filling, an aluminum alloy having higher strength than the currently used 6061 alloy is needed. It has been known that increase in the Si content in 6000 series aluminum alloy brings about increase in the strength. In this study, a 6061 aluminum alloy with Si content of highest level (6061HS), 6061 alloy with a typical composition have been subjected to slow strain rate technique (SSRT) tensile tests in a moist air to assess the resistance to hydrogen embrittlement, and also to thermal desorption spectroscopy (TDS) to investigate the hydrogen behavior. The results obtained have been discussed in terms of the effect of Si content. Moreover, to investigate the effect of grain size, 6061HS alloy sheets with different grain size have been also subjected to the SSRT tensile tests and TDS.
Storage of CO2 in Low Al2O3 EAF Oxidizing Slag by Grinding with Vibration Mill
Authors: Muhd Nor Nik Hisyamudin , Yokoyama Seiji , Umemoto Minoru
Published: June 2010

The investigation of the behavior of CO2 absorption into the low Al2O3 electric arc furnace (EAF) oxidizing slag under wet grinding was investigated in this paper. The slag was wet ground in the vibration ball mill in the presence of CO2 at room temperature. The observation of the CO2 absorption was made with constant pressure method. The CO2 absorption increased steeply in the early stage of grinding. It occurred simultaneously with the grinding and immediately ceased when the grinding was stopped. The CO2 absorption occurred at the interface between the slag and the water which was saturated with CO2. The CO2 absorption increased as the finer particles were formed by the grinding process, and as the interface between slag and water was increased by the vibration process. A large amount of CO2 absorption and high conversion ratio was observed in the oxidizing slag with low Al2O3 in comparison with those of the slag with the high Al2O3 content.
Microstructural Evolution during the Novel Quenching and Partitioning (Q&P) Heat Treatment of Steel
Authors: Bigg Timothy D. , Edmonds David
Published: June 2010

The novel non-equilibrium heat treatment procedure known as Quenching and Partitioning (Q&P) may offer the prospect of higher strength steel products with enhanced formability based upon martensitic microstructures containing controlled quantities of carbon-enriched retained austenite. The Q&P process requires an interrupted quench and isothermal annealing (partitioning) step at intermediate temperatures, whereby untransformed austenite can be thermodynamically stabilised by carbon migration from supersaturated martensite regions. The concept is comparable to that producing carbide-free bainite, for example, in TRIP-assisted steel, although Q&P allows separation of the ferrite formation and austenite enrichment stages of the process. However, although the Q&P concept is readily understood, evolution of the microstructure during interrupted quenching and partitioning has been inferred indirectly from dilatometer studies and metallographic examination after final quenching to room temperature. Consequently, a model alloy was developed in which the sequential steps of heat treatment could be separated for direct inspection by conventional metallography, X-ray diffraction and neutron diffraction techniques.
Phase Transformation and Annealing Behavior of SUS 304 Austenitic Stainless Steel Deformed by High Pressure Torsion
Authors: Shuro Innocent , Umemoto Minoru , Todaka Yoshikazu , Yokoyama Seiji
Published: June 2010

SUS 304 austenitic stainless steel was subjected to severe plastic deformation (SPD) by the method of high pressure torsion (HPT). From a fully austenitic matrix (γ), HPT resulted in phase transformation to give a two phase structure of austenite (γ) and martensite (α') by the transformation γα'. The phase transformation was accompanied by an increase in hardness (Hv) from 1.6 GPa in the as annealed form to 5.4 GPa in the deformed state. Subsequent annealing in temperature range 250oC to 450oC resulted in an increase in both α' volume fraction and hardness (6.4 GPa). Annealing at 600oC resulted in a decrease in α' volume fraction hardness.
Slide-Bend Forming of Very Thin Metal Sheet Using Slide-Ironing Tool
Authors: Nakagawa Ryo , Matsuno Takeharu , Marumo Yasuo , Hayano Yuya , Ruan Li Qun , Sakamoto Hidetoshi , Harada Hiroshi
Published: June 2010

Characteristics of slide-bend forming were investigated. In this process, foil specimens can be bent to various shaped products by indenting and sliding a tool. The effects of the tool indentation load, the foil thickness and the number of slide repetition on the bending angle were examined experimentally for three kinds of foil materials. In addition, the deformation of bent region was examined using a rigid-plastic finite element analysis. Bending angle increased with increasing the indentation load or decreasing the foil thickness. When the number of slide repetition increased, the bending angle increased slightly. The slide repetition can be effective for adjusting bending angle slightly. By sliding a thin edge-shaped tool relative to the foil specimen, bending angle and radius of curvature of specimens can be controlled freely.
The Oxide Inclusion and Heat-Affected-Zone Toughness of Low Carbon Steels
Authors: Shu Wei , Wang Xue Min , Li Shu Rui , He Xin Lai
Published: June 2010

The relationship between the oxide inclusions and the Heat-affected-zone (HAZ) toughness of microalloying steels has been investigated. The low carbon steels are smelted with special oxide introduction technique and the properties of HAZ has been studied with thermo-simulation. The optical microscope and SEM were used to analyze the size, composition and distribution of the inclusions, the mechanical properties after thermo-simulation was also analyzed. The results show that the inclusions in steel are mainly Ti and Al oxide with MnS, these complex inclusions are well distributed and the size is less than 3 micron. Microstructure of HAZ consists of intragranular acicular ferrite (IAF), intergranular ferrite and small amount of lath bainite while the cooling time during the phase formation is short. After the thermo simulation with the cooling time between 800°C and 500°C (t8/5) increasing the toughness of HAZ decreased and the size of prior austenite grain increased. Inclusions which located near the prior austenite grain boundary couldn’t induce the nucleation of IAF, only the ones inside the prior austenite grain can promote IAF’s growth.
Unconventional Short-Term Glow Discharge Nitriding of 316L Austenitic Steel
Authors: Frączek Tadeusz , Olejnik Michał , Jasiński Jarosław
Published: June 2010

The AISI 316L grade austenitic steel after glow discharge nitriding at a temperature of T = 598 K and for duration of  = 10,8 ks, for different variants of specimen arrangement in the glow-discharge chamber was investigated. In the first variant specimens were placed on the cathode and in the second variant specimens were positioned also on the cathode, but shielded with a booster screen. In order to assess the effectiveness of nitriding process variants a profile analysis examination of obtained surface layers, surface hardness tests and surface layer hardness profile examination, analysis of surface layer structures and corrosion resistance tests were carried out. It was found that application of a booster screen effects in a nitrogen diffusion depth increment into the 316L austenitic steel, resulting in a surface layer thickness escalation.
Influence of Cu Contents in Hot Shortness of Cu Bearing EAF Steels
Authors: Lee Young Sup , Jung Choon Ho , Jiang Ying Hua , Im Jae Taek , Lee Young Hoo , Chang Sam Kyu , Kim Man Rae , Jun Joong Hwan
Published: June 2010

The surface cracking behaviors of Cu-bearing steels were studied under similar conditions of the direct hot charging processes. Several specimens with various Cu contents from 0.11 to 0.38% were prepared, the oxidation tests were performed at the temperature of 1100, 1150 and 1200°C, and the hot compression tests were conducted at 1050°C using the Gleeble 3500 in order to examine the Cu induced surface cracks. The surface cracks increased gradually as the Cu-rich phase above the critical level increased. The critical level of Cu-rich phase for the specimens of high Cu contents (0.38%) reaches with a thin scale layer. However, the specimens with lower Cu content (0.13%) the critical level of Cu-rich phase occurred with a thick scale layer. The oxidation potentials of steel were affected by temperature, time, atmosphere and other elements. The oxidation rates of Cu bearing steels decreased with increasing Cu contents. It is suggested that the oxidized scale thickness is the one of important factors inducing the surface cracks by Cu contained steels in direct hot charging process.
Fundamentals of Spark-Plasma Sintering: Applications to Net-Shaping of High Strength Temperature Resistant Components
Authors: Olevsky Eugene , Khaleghi Evan , Garcia Cristina , Bradbury William
Published: June 2010

Spark-plasma sintering (SPS) is an emerging powder consolidating technique which provides significant advantages to the processing of high temperature materials with poor deformability into configurations previously unattainable. Net-shaping capabilities of spark-plasma sintering are analyzed both theoretically and experimentally. Modeling and experimentation are conducted for cylindrical, prismatic, and complex powder specimen shapes. The impact of the “shape factor” on the non-uniformity of temperature, relative density, and grain size spatial distributions is analyzed. The modeling results are compared to the experimentally obtained data on the spark plasma sintering of high strength temperature resistant powder-based materials. The conducted research indicates the promising capabilities and addresses the challenges of spark-plasma sintering of complex-shape parts.
Construction of a High Temperature Grade 91 Sodium Component Test Loop
Authors: Lee Hyeong Yeon , Lee Jae Han , Lee Tae Ho , Lee Jae Hyuk Eoh , Kim Tae Joon , Lee Yong Bum
Published: June 2010

A large scale sodium test facility of ‘CPTL’(Component Performance Test Loop) for simulating thermal hydraulic behavior of the Korean demonstration fast reactor components such as IHX(Intermediate Heat Exchanger), DHX(Decay Heat Removal Heat Exchanger) and sodium pump under development by KAERI is to be constructed. The design temperature of this test loop is 600°C and design pressure is 1MPa. The three heat exchangers are made of Grade 91 steel. Another sodium test facility of the ‘STEF’(Sodium Thermal-Hydraulic Experimental Facility) will be constructed next to the CPTL facility to simulate the passive decay heat removal behavior in the sodium cooled fast reactor. In this paper, the overall facility features of the CPTL and STEF are introduced and preliminary conceptual design of the facilities are carried out.
Grain Refinement and Nuclei Formation Mechanism of Ni-Based Superalloy K417 with Low Voltage Pulsed Magnetic Casting
Authors: Yang Yuan Sheng , Ma Xiao Ping , Li Yingju
Published: June 2010

Low Voltage Pulsed Magnetic Casting (LVPMC) is developed for grain refinement castings in recent years. This paper investigates the grain refinement effect of LVPMC on superalloy K417 and deals with the effects of cooling rate and superheating on grain refinement, as well as grain refinement mechanism. The experimental results show that the grains in the alloy are equiaxed and refined to 60 m averagely. The melt flow and Joule heat during solidification are modeled and simulated to reveals the grain refinement mechanism. It is considered that the melt vibration and convection caused by the pulsed magnetic field, as well as cooling rate and superheating contribute to the refinement of solidified grains.
Alloy Design of Nb-Si Based High Temperature Alloys by Phase Stability Control
Authors: Miura Seiji , Tanahashi Tatsuichi , Mishima Yoshinao , Mohri Tetsuo
Published: June 2010

In order to spheroidize -Nb5Si3 strengthening phase embedded in Nb matrix for attaining a good room temperature toughness of Nb-Si alloy, the authors have proposed a microstructure control technique by combining eutectic and eutectoid reactions. Nb3Si intermetallic compound formed during solidification is a key phase for the microstructure control, but its stability is very sensitive to the alloying elements. Nb3Si disappears by adding as small as 3 at% of W and Mo, while these elements are very effective for the solid solution strengthening of Nb phase. For a further alloy development, establishment of an alloy design concept based on the control of phase stability of Nb3Si is needed. Similarly to ferrous alloys such as stainless steels where Cr and Ni are added to control the stability of bcc phase and fcc phase, two alloying elements (one is a stabilizing element and the other is a destabilizing element for Nb3Si phase) are added to a Nb-Si binary master alloy and their microstructure is investigated using SEM. The stabilizing element Ta is found to enlarge the composition area where Nb3Si exists even with the destabilizing element Mo, and it is confirmed that the phase stability concept is useful for designing Nb-Si based alloys.
Effect of Y on Microstructure and Mechanical Properties of a Ti Alloy
Authors: Liu Zhi Guang , Zhang Chang Jiang , Chai Li Hua , Chen Yu Yong , Woo Kee Do
Published: June 2010

A near-α high temperature titanium alloy, Ti-6Al-2.5Sn-4Zr-0.7Mo-0.30Si, was produced with various Y contents from 0 to 0.7wt% by arc-melting technique to study the influence of Y on its microstructure and mechanical properties. It was found that small amount of Y obviously refines the grain size of Ti-6Al-2.5Sn-4Zr-0.7Mo-0.30Si alloy. SEM and TEM observations revealed that Y-containing phase precipitated at the β grain boundary in the form of Y2O3 particles. Hardness and compression tests performed at room temperature revealed the strengthening effect of Y.