bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Forging Processing Parameters on Axial Effective Strain in Heavy Forgings
Authors: Lin Yong Cheng , Chen Ming Song , Zhang Jun
Published: June 2010

Heavy forgings are the essential parts of some nuclear, electrical power generation, rolling mill equipments. Based on the experimental results, one thermo-mechanica1 coupled finite element model was developed to study the effects of forging processing parameters, including the deformation degree, tool width ratio, and blank width ratio, on the axial effective strain during stretching process of heavy forgings. Results show that: (1) The effective strain around the central point rapidly increases as the deformation degree was increased. When the deformation degree is larger than 15%, there are little changes of the effective strain along the deformed block centerline. (2) The effective strain in central point increases and then decreases with the increase of tool width ratio, and the critical tool width ratio is 0.8, which is valid for most stretching processes. (3) The effective strain increases with the increase of initial blank width ratio, and the effects of blank width ratio on the effective strain in axial centerline are most obvious near the central point.
Effects of Hub Contact Shape on Contact Pressure and Fatigue Life in a Press-Fitted Shaft
Authors: Lee Dong Hyung , Kwon Seok Jin , Seo Jung Won , You Won Hee
Published: June 2010

The objective of this study is to clarify the effect of hub contact shape on contact pressure and fatigue life with regard to the selection of a suitable taper design near the end of the fit. A numerical asymmetric-axisymmetric finite element model was developed in order to determine the contact stress state of press-fitted shaft by using four types of tapered contact surfaces on the hub. The variations of fatigue crack initiation life according to the change of tapered contact surfaces on the hub were evaluated by using the Smith-Watson-Topper (SWT) multiaxial fatigue criterion. As the result, comparing with the contact pressure and the fatigue crack initiation life, maximum decrease of contact pressure and maximum increase of fatigue crack initiation life were obtained for the 1/400 m/m tapered hub subjected to a bending load near the fretting fatigue limit. Furthermore, as the change of bending load, the optimal amout of taper in hub which fatigue life gets into maximum is varied. Therefore, we suggest that the best performance, in terms of pressure distribution and fatigue life of press fit, can be obtained by using a proper taper values for the hub element.
Thermal-Structural Finite Element Analysis of Injection Moulding Dies with Optimized Cooling Channels
Authors: Saifullah Abul B.M. , Masood Syed H. , Sbarski Igor
Published: June 2010

One of the most important aspects of mould design in injection moulding is the provision of suitable and adequate cooling arrangements. Proper cooling channel design in the mould is an important aspect as it affects cycle time and quality of the injection moulded plastic part. A new cooling channel design with copper tube insert can reduce cycle time by optimal and uniform heat transfer in the mould. In this research work a comprehensive FEA transient thermal-structural analysis has been performed with ANSYS simulation software to understand robustness and longevity of an industrial plastic part mould with these cooling channels and compared with conventional straight cooling channels. Autodesk Moldflow Insight (AMI) also has been used to get essential process parameter values for analysis. Result shows that by inserting copper tube in the cooling channels, a mould can increase cooling efficiency and can last for higher number of cycles before fatigue failure, thus increasing production rate.
Application of High Power DC Arc Plasma for Mass Production of High Quality Freestanding Diamond Films and Diamond Film Coated Cutting Tools
Authors: Lu Fan Xiu , Li Cheng Ming , Tong Yu Mei , Tang Wei Zhong , Chen Guang Chao , Song Jian Hua , Hei Li Fu
Published: June 2010

As quasi-thermodynamic equilibrium plasma, DC Arc Plasma has the advantage of very high gas temperature and thus the very high degree of activation of the precursors for diamond film deposition. The present paper reviews the progresses in the R&D of the novel high power dc arc plasma jet CVD system with rotating arc and operated at gas recycling mode for large area high quality diamond film deposition, developed at the University of Science and Technology Beijing (USTB) in the mid 1990s of the 20th century. Thanks to the continuous efforts made in the technological improvement in the past 15 years, considerable progresses have been achieved in the commercialization of this high power dc arcjet CVD system, which is now capable of mass production of large area high quality freestanding diamond films for optical, thermal, and mechanical (tool) applications. The present status in the commercialization and the property level of the resultant diamond films in optical, thermal, mechanical, dielectric, oxidation resistance, sand erosion resistance, and laser damage threshold etc. are presented. Based on the same high power dc arcjet technology, a novel high current extended dc arc plasma (HCEDCA) CVD system has been developed which successfully changed the diamond film deposition mode from 2D planar deposition in to 3D deposition (as confined by two hollow (virtue) columns). It is demonstrated to be advantageous for mass production of diamond thin film coated WC-Co cutting tools. Recent results in the R&D of thin diamond film coated WC-Co drills and end mills, and the results in field tests are discussed.
Fabrication of Numerous Ferromagnetic Metal Nanowires Using Electrodeposition Technique
Authors: Ohgai Takeshi , Fujimaru Takafumi , Takao Keizo , Kagawa Akio
Published: June 2010

To synthesize an array of numerous ferromagnetic nanowires, iron-group metals such as Ni, Co, Fe, Ni-Fe and Co-Fe alloys were electrodeposited from aqueous solution into a nanoporous template with numerical cylindrical nanochannels . The shape of nanowires was precisely transferred from the nanochannel template and the aspect ratio reached to around 150. Magnetic hysteresis loops revealed that Ni, Co and Fe nanowires were spontaneously magnetized to the long axis direction. Coercive force of the nanowires with 6000 nm in length was increased in decreasing the pore-diameter. The coercive force of Co nanowires with 40 nm in diameter has increased up to 1084 Oe.
Development of Infrared Ray Curing Technology at Continuous Coil Coating Line
Authors: Kyung Jae Park , Dae Il Woo
Published: June 2010

The No. 1 continuous coil coating line of Dongbu Steel produces 70,000 tons of commercial quality products annually, and the pre-coated metal (PCM) products are widely used for a home appliances or building materials. The lines are consisted of pre-treatment, painting, curing and tension levelling processes. The typical curing methods are injection of hot air, infrared rays, electron beam, or induction heated oven. Peak metal temperature (PMT) is the vital factor that determines the product quality. The curing oven of No. 1 continuous coil coating line revamped from injection of hot air to infrared rays type and operated from 2007. A PMT setup model was developed for control the strip temperature, and applied in site, and systemized. The operation results showed that the accuracy of the setup model achieved above 96% consistently.
Effect of Niobium Content on Laminar Precipitate and High Temperature Mechanical Properties of 21-2N Valve Steel
Authors: Cheng Shi Chang , Liu Zheng Dong , Lin Zhao Jie , Bao Han Sheng
Published: June 2010

Effect of niobium content on laminar precipitate and high temperature mechanical properties of 21-2N vavle steel was systematically studied, using specimens contain 0.26%, 0.43%, 0.65% 0.82% and 1.06% Nb. After different solid solution treatment and 750 °C aging heat treatment, experimental results showed that laminar precipitate was suppressed by niobium addition, and with the increasing of niobium content, laminar precipitate content decreased and size, distribution and morphology of laminar precipitate was meliorated. Then creep rupture strength and fatigue strength of experimental steels are improved with increasing of niobium.
Structure and Properties of Cold Spray Coatings
Authors: Spencer Kevin , Luzin Vladimir , Zhang Ming Xing
Published: June 2010

Cold spray coatings are considered promising for surface protection of light metal substrates but the mechanisms of bonding and coating build-up are still poorly understood and are the subject of continuing debate. A variety of coating/substrate combinations have been characterised in detail using electron microscopy to examine the nature of the interparticle and particle/substrate interfaces. Through-thickness residual stress profiles obtained via neutron diffraction show that the internal stress varies significantly depending on the coating materials. The work will present a picture of the cold spray deposition process using different material examples.
Multi-Layer Coating for Optical Mold of Strengthening by Electroplating Ni-W and Electroless Plating Ni-Mo-P by Nonisothermal Method
Authors: Chang Yun Feng , Hou Kung Hsu , Ger Ming Der
Published: June 2010

The development of optical mold coatings has become a key technology in precision optical components in recent years. Researchers are still seeking ideal electroforming materials capable of resisting higher temperature and improve the lifespan of optical mold. Examples of these materials include Ni-W, and Ni-Mo-P alloy plating, among others. However, the literature rarely mentions these alloys as protective coatings. This may be because coating stability, flatness, and strength cannot achieve the desired protective effects. This study develops a combination of two wet electrochemical processes to form a multi-layer coating on optical molds. This coating consists of Ni-W, and Ni-Mo-P alloys. The proposed treatment process attempts to enhance the mechanical strength of the mold and extend its lifespan. We first used electro-deposition to form a thick-film Ni-W coating, and then applied the electroless plating by nonisothermal deposition method (NITD) to create a Ni-Mo-P thin-film and form a multi-layer coating. We also measured the composition, hardness, and elastic modulus of the protective coating as a reference basis for the development of optical molds. The results of this study reveal the appropriate process parameters to provide the multilayer films with a high strength and flat surface. This article can serve as a reference for the development of optical mold coatings.
The Effect of Temperature on the Tensile Properties of Steel 0Cr18Ni9
Authors: Li Wei Fen , Niu Wei , Hao Zhi Ming , Li Ming Hai
Published: June 2010

Experiments of tensile mechanical properties of steel 0Cr18Ni9 are done on the MTS 810 tensile testing machine, and the temperature range is from 20°C to 1200°C. The stress vs. strain curves are obtained. Results show that the elastic modulus, yield stress and tensile strength decrease with increasing temperature .Based on the experiment results, the functions of the elastic modulus, yield strength and tensile strength versus temperature are represented by polynomial.
Densification Behavior in Spark-Plasma-Sintering of MgAl2O4 Spinel
Authors: Morita Koji , Kim Byung Nam , Yoshida Hidehiro , Hiraga Keijiro
Published: June 2010

The densification mechanism in park-plasma-sintering (SPS) processing was examined in MgAl2O4 spinel. As the relative density ρt increases, that is, as the effective stress σeff decreases, stress exponent n evaluated from effective stress-densification rate relationship continuously varies from n  4 to n  1. TEM observation shows that significant stacking faults caused by partial dislocations are frequently observed in the low ρt region. The results suggest that, for spinel, the predominant densification mechanism in SPS processing changes with ρt from plastic flow by a partial dislocation motion in the low ρt region (n  4) to diffusion-related creep in the high ρt region (n  1).
Reaction Sintering Kinetics of Mullite Ceramics Prepared from High Aluminum Fly Ash
Authors: Li Jin Hong , Ma Hong Wen , Tong Ling Xin , Jiang Xiao Qian
Published: June 2010

This research presented the kinetics of mullite formation in fly ash-bauxite reactants couples. Experiment on isothermal conversion of fly ash-bauxite at 1100°C, 1300°C, 1500°C has been carried out. XRD was used to quantitatively measure the content of mullite specimens sintered at different temperatures and times. The kinetics curve of conversion ratio versus time has been drawn. The results obtained showed that the full transformation of fly ash-bauxite to mullite takes place between 1300 °C and 1500 °C. The activation energy of secondary mullite formation is deduced to be 151 kJ/mol in the range of 1100-1500°C. The growth morphology parameter, n, is about 1.14 and 0.45 at 1100°C and 1500°C, respectively, indicating that bulk nucleation is dominant in mullite crystallization followed by three-dimensional growth of mullite crystal controlled by diffusion, but at 1500 °C diffusion process dominates mullite formation process.
Characterization and Energy Storage Density of BaTiO3 - Ba(Mg1/3Nb2/3)O3 Ceramics
Authors: Li Yi Qiu , Liu Han Xing , Yao Zhong Hua , Xu Jing , Cui Yun Jiang , Hao Hua , Cao Ming He , Yu Zhi Yong
Published: June 2010

The energy storage density of (1-x) BaTiO3 – x Ba(Mg1/3Nb2/3)O3 (x = 0, 0.1, 0.2, 0.3) ceramics was investigated. The microstructure of samples was characterized by scanning electron microscopy (SEM). The energy storage density was calculated from the P-E hysteresis loops measured at room temperature. Experimental results show that the energy storage density of 0.9 BaTiO3 – 0.1 Ba(Mg1/3Nb2/3)O3 ceramics is highest among all compositions. At 15.8kV/mm electric field, the energy storage density of the sample can reach up to 1.07J/cm3, which is about 1.5 times higher than pure BaTiO3. The improvement of the energy density can be due to two factors: one is the improved breakdown strength caused by the optimized microstructure, the other is the decreased remnant polarization. This result indicates that bulk 0.9 BaTiO3 – 0.1 Ba(Mg1/3Nb2/3)O3 ceramic has advantages compared with pure BaTiO3 ceramic for energy storage applications, and with further improvements in microstructure and reduction of sintering temperature, could be a good candidate for energy storage capacitors.
High Performance of Sub-Micro-Layered Ti3C2/(Cu-Al) Cermets Prepared by In-Situ Hot-Extruding Method
Authors: Huang Zhen Ying , Zhai Hong Xiang , Li Meng Qi , Chen Xin Hua
Published: June 2010

A series of new sub-micro-layered Ti3C2/(Cu-Al) cermets were prepared by in-situ hot-extruding a mixture of Ti3AlC2 and Cu powders, and some properties of these materials were tested. These cermets have quite high fracture strength and electric conductivity, due to the strong combination between Ti3C2 and (Cu-Al), and a special network microstructure formed by the (Cu-Al) phase surrounding the sub-micro-sheet layered Ti3C2 phase. The in-situ hot-extruding after pressless sintering can effectively eliminate pores contained in (Cu-Al) phase, and accelerate the diffusing of Cu towards the interlayer between Ti3C2 layers, so the fracture strength and electric conductivity are increased. With increasing the content of the ceramic phase, the strength of the cermets can be further increased while the ductility is reduced.
Nanostructured Titanium Biomaterials: Understanding and Applications
Authors: Im Yeon Min , Khang Dong Woo , Nam Tae-hyun
Published: June 2010

Nanostructured implant materials are considered as promising future biomaterials. Specifically, titanium based nanomaterial is the mostly used implant materials in orthopedic, dental and vascular surgeries. Due to the advantage of nanoscale features, treatment with nano porous and nano bump surface features have shown enhanced biocompatibilities, such as adhesion, proliferation and differentiation for bone and vascular cells. In addition, nanotoxicity issue with immune cells (macrophages) is currently paramount interest for determining subsequent tissue cellular response on implanted biomaterials. In this review, we demonstrated altered cellular interaction of bone, vascular cells on nanostructured titanium based alloys/materials through systematic controlling of nanoscale surface features, such as porosity and nanobumps. All this knowledge will be beneficial for both understanding and designing nanostructured biomaterials for increasing biocompatibility, thus, all these endeavors will lead increment of functionality of biomaterials and will eventually prolong the life time of implanted biomaterials.
In Vitro and In Vivo Evaluation Of Calcium Phosphate Bone Graft Substitutes
Authors: Song Ho Yeon , Kim Young Hee , Anirban Jyoti M. , Byun In Seon , Kwak Kyung A , Lee Byong Taek
Published: June 2010

Calcium phosphate ceramics such as hydroxy apatite (HA), β-tricalcium phosphate (β-TCP) and bicalcium phosphate (BCP) have been used as a bone graft biomaterial because of their good biocompatibility and similarity of chemical composition to natural bones. To increase the mechanical and osteoconductive properties, the granules and spongy type porous bone graft substitutes were prepared by fibrous monolithic process and polyurethane foam replica methods, respectively. The pore sizes obtained using these approaches ranged between 100-600 µm. The cytotoxicity, cellular proliferation, differentiation and ECM deposition on the bone graft substitutes were observed by SEM and confocal microscopy. Moreover, the scaffolds were implanted in the rabbit femur. New bone formation and biodegradation of bone graft were observed through follow-up X-ray, micro-CT analysis and histological findings. After several months (2, 3, 6, 12 and 24 months) of implantation, new bone formation and ingrowths were observed in defect sites of the animal by CaP ceramics and 2 to 3 times higher bone ingrowths were confirmed than that of the normal trabecular bones in terms of total bone volume (BV).
New SMA Actuator with High Energy Efficiency and Quick Response
Authors: Jee Kwang Koo , Han Jun Hyun , Park J.M. , Jang Woo Yang
Published: June 2010

The main drawbacks of SMA actuators are a slow response and a waste of electric power. The power should be continuously supplied for SMA elements to remain in the austenite state until the actuator begins to move to the other position. The problems are more serious when batteries and thick SMA elements are used. We develop a new SMA actuator which consumes little energy and responds very quickly. The actuator consists of a specially designed bias spring structure, and two SMA elements which exert the force in opposite direction to each other. The bias spring, unlike a common spring which has one stable position, has two stable positions. A SMA1, for instance, contracts on heating by electricity, the actuator takes one stable configuration. No further power supply is necessary to maintain the stable position, providing enough time for the SMA1 to cool. When the other SMA2 is heated, it contracts with enough force to move the bias spring and to expand the already-cooled SMA1. Power supply stops immediately after the actuator takes the other stable configuration, causing power saving and quick response.
Improvement of Mechanical Performance and Biocompatibility of Spinal Implant Rod Made of Beta-Type Ti-Nb-Ta-Zr Alloy
Authors: Niinomi Mitsuo , Narita Kengo , Nakai Masaaki , Akahori Toshikazu , Tsutsumi Harumi , Oribe Kazuya
Published: June 2010

Mechanical properties of beta-type biomedical Ti-29Nb-13Ta-4.6Zr (mass %) (TNTZ), which exhibits non-toxicity and a low modulus similar to that of cortical bone, is improved by thermomechanical treatments, including severe cold swaging. Simultaneously, the biocompatibility of a TNTZ spinal implant rod with living tissue is evaluated using ovines, and TNTZ is proved to show good biocompatibility with bovine tissue.
Pack Cementation Treatment of Titanium Using Tetracalcium Phosphate Powder for Biomedical Applications
Authors: Ueda Kyosuke , Suto Hajime , Nakaie Kaori , Narushima Takayuki
Published: June 2010

The surface modification of commercially pure titanium (CP Ti) by pack cementation treatment at 973 K using tetracalcium phosphate (Ca4(PO4)2O, TTCP) slurry was investigated. An HAp phase and a CaTiO3 phase were observed on the reaction layer of the CP Ti substrate after pack cementation treatment at 973 K for 86.4 ks. TTCP powder decomposed to HAp and CaO, and CaO reacted with TiO2 to form CaTiO3. The reaction layer on the CP Ti substrate consisted of inner and outer layers and the particles were in the outer reaction layer. The pores observed on the reaction layer were formed by the detachment of particles from the outer layer. The bonding strength of the reaction layer was 68.1 MPa. Apatite completely covered the surface of the pack-cementation-treated CP Ti after immersion in Kokubo solution for 21.6 ks; such rapid apatite formation suggests that pack cementation treatment improves the biocompatibility of titanium.
Effects of Deformation Strains and Annealing Temperatures on Mechanical Properties of Martensitic Steels
Authors: Lee Jong Chul , Kang Ui Gu , Oh Chang Suk , Kim Sung Joon , Nam Won Jong
Published: June 2010

The effects of deformation strains and annealing temperatures on microstructures and mechanical properties of martensitic steels were examined. The amount of cold deformation was changed as 30%, 50% and 60%, and annealing temperatures varied from 500°C to 600°C. In samples cold rolled 30%, the dominant microstructure for an annealing at 500°C was dislocation substructures with uniformly distributed rod-shaped carbide particles. For an annealing at 600°C, the microstructure consisted of equiaxed ultrafine grains, spherical carbide particles and elongated dislocation substructures. A proper annealing temperature for martensitic steels received 30% reduction, showing a good combination of a high strength, 1230MPa, and an adequate total elongation. 9.4%, was found as 500°C.
Heat Treatment of ASTM F75 Co-Cr-Mo-C-Si-Mn Alloys
Authors: Alfirano Alfirano , Mineta Shingo , Namba Shigenobu , Yoneda Takashi , Ueda Kyosuke , Narushima Takayuki
Published: June 2010

In this study, the carbide dissolution and formation of biomedical Co-28Cr-6Mo-0.25C-1Si (1Si) and Co-28Cr-6Mo-0.25C-1Mn (1Mn) alloys occurring during solution treatment and aging were investigated. The addition of Si or Mn markedly affected the behavior of precipitates during heat treatment. The alloy with added Si required a longer solution treatment time for complete precipitate dissolution as compared to the alloy with added Mn. Blocky M23C6-type carbide was observed during solution treatment at 1448–1523 K. Starlike precipitates were observed in the 1Si and 1Mn alloys at 1523–1548 K and 1523 K, respectively. The starlike precipitates exhibited two types of morphologies: dense and stripe patterned. The starlike precipitates with dense and stripe-patterned appearances were a -phase and M23C6¬-type carbide + metallic -phase, respectively. An M23C6-type carbide and an -phase were formed during the aging of both the 1Si and the 1Mn alloys. In addition, an intermetallic -phase was detected during the aging of the 1Si alloy at 1373 K.
Biodegradable Mg-Ca and Mg-Ca-Y Alloys for Regenerative Medicine
Authors: Li Yun Cang , Li Mei Heng , Hu Wang Yu , Hodgson Peter , Wen Cui E
Published: June 2010

In this study, Mg-xCa (x = 0.5, 1.0, 2.0, 5.0, 10.0, 15.0 and 20.0 %, wt.%, hereafter) and Mg-1Ca-1Y alloys were investigated as new biodegradable bone implant materials. The compressive strength, ultimate strength and hardness of the Mg-Ca alloys increased, whilst the corrosion rate and biocompatibility decreased, with the increase of the Ca content in the Mg-Ca alloys; higher Ca content caused the Mg-Ca alloy to become brittle. Solutions of simulated body fluid (SBF) and modified minimum essential media (MMEM) with the immersion of Mg-xCa and Mg-1Ca-1Y alloys showed strong alkalisation. The yttrium addition to the Mg-Ca alloys does not improve the corrosion resistance of the Mg-1Ca-1Y alloy as expected compared to the Mg-1Ca alloy. It is suggested that Mg-Ca alloys with Ca additions less than 1.0 wt.% exhibited good biocompatibility and low corrosion rate.
Changes of Bone Quality and Quantity in rhM-CSF-Treated Osteopetrotic (op/op) Mice
Authors: Lee Jee Wook , Nakano Takayoshi
Published: June 2010

Measurements of bone mineral density (BMD) cannot accurately predict the risk of bone fracture in some clinical cases; however, BMD is a useful index for assessing the bone condition. Recently, various parameters related to bone strength have been investigated. Among them, we have focused on the preferential orientation of biological apatite (BAp) crystallites analyzed by microbeam-X-ray diffraction, a powerful tool for analyzing BAp crystallites in bones. BAp, a dominant component of bone, is an anisotropic ionic crystal with a hexagonal lattice. In this study, we investigated the mechanism underlying BAp orientation during endochondral or membranous ossification by administering macrophage colony-stimulating factor (M-CSF) to osteopetrotic (op/op) mice lacking M-CSF. op/op mice were treated with intraperitoneal injections of 5 μg recombinant human M-CSF (rhM-CSF); the first injection was administered on the 14th day after birth. In the treated op/op mice, the bone marrow cavities expanded significantly, and this expansion was accompanied by an increase in the number of osteoclasts. Moreover, the degree of BAp orientation along the longitudinal axis was higher in the treated group than in the untreated group. These results suggest that M-CSF is one of the important parameters controlling the preferential alignment of the BAp c-axis.
Formation of Hydroxyapatite on Titanium Oxides in Simulated Body Fluid under UV Irradiation
Authors: Ueda Masato , Sai Hiroki , Ikeda Masahiko , Ogawa Michiharu
Published: June 2010

Hydroxyapatite (HAp), Ca10(PO4)6(OH)2, is known to precipitate on bioactive materials by soaking in simulated body fluid (SBF). The formation of HAp on TiO2 and CaTiO3 surfaces under continuous ultraviolet (UV) irradiation was investigated in this study. Pure Ti substrates were chemically treated with H2O2/ HNO3 solution at 353 K for 20 min to form a TiO2 gel layer. The samples were then hydrothermally treated with an aqueous NH3 or an aqueous Ca(OH)2 solution in an autoclave at 453 K for 12 h. An adhesive and sufficiently crystallized anatase-type TiO2 film or perovskite-type CaTiO3 film could be synthesized on the Ti surface, respectively. The samples were immersed in SBF in darkness or under UV irradiation. The UV irradiation promoted the formation of HAp, which may be due to the generation of functional Ti-OH or Ti-O groups on both surfaces. On the other hand, the UV light also produces electron-hole pairs in the product films. In TiO2, much photogenerated holes migrated to the surface and repelled the Ca2+ ions in the solution. As a consequence, the UV irradiation suppressed the formation of HAp thin film on the surface of TiO2.
A Novel Biodegradable Multichamber Microstructure for Implantable Drug Controlled Release
Authors: Yu Rui Xia , Zhou Xiang Yang , Zhao Zeng
Published: June 2010

The research work reported in this paper design a novel biodegradable multichamber microstructure for implantable drug controlled release by introducing the approach of topology optimization. It is therefore highly desirable to overcome these restrictions that pre-defined topology of the device result in difficulty to obtain a linear or pulsed drug release profile. The designed biodegradable multichamber microstructure is fabricated using UV-LIGA microfabrication and Micro-molding technique. The simulation results show that the multichamber microstructure exhibits a preferable linear drug release profile.
On the Effective Mechanical Properties of Fluid-Saturated Composites: A Homogenization Approach
Authors: Ma Lian Hua , Rolfe Bernard F. , Yang Qing Sheng , Yang Chun Hui
Published: June 2010

Composites containing saturated fluid are widely distributed in nature, such as saturated rocks, colloidal materials and biological cells. In the study to determine effective mechanical properties of fluid-saturated composites, a micromechanical model and a multi-scale homogenization-based model are developed. In the micromechanical model the internal fluid pressure is generated by applying eigenstrains in the domain of the fluid phase and the explicit expressions of effective bulk modulus and shear modulus are obtained. Meanwhile a multi-scale homogenization theory is employed to develop the homogenization-based model on determination of effective properties at the small scale in a unit cell level. Applying the two proposed approaches, the effects of the internal pressure of hydrostatic fluid on effective properties are further investigated.
Defect and Damage Evolution Quantification in Dynamically-Deformed Metals Using Orientation-Imaging Microscopy
Authors: Gray III George (Rusty) T. , Livescu Veronica , Cerreta Ellen K.
Published: June 2010

Orientation-imaging microscopy offers unique capabilities to quantify the defects and damage evolution occurring in metals following dynamic and shock loading. Examples of the quantification of the types of deformation twins activated, volume fraction of twinning, and damage evolution as a function of shock loading in Ta are presented. Electron back-scatter diffraction (EBSD) examination of the damage evolution in sweeping-detonation-wave shock loading to study spallation in Cu is also presented.
Towards Radiation Tolerant Nanostructured Ferritic Alloys
Authors: Miller Michael K. , Hoelzer David T. , Russell Kaye F.
Published: June 2010

The high temperature and irradiation response of a new class of nanostructured ferritic alloys have been investigated by atom probe tomography. These materials are candidate materials for use in the extreme environments that will be present in the next generation of power generating systems. Atom probe tomography has revealed that the yttria powder is forced into solid solution during the mechanical alloying process andsubsequently 2-nm-diameter Ti-, Y- and O-enriched nanoclusters are formedduring the extrusion process. These nanoclusters have been shown to be remarkably stable during isothermal annealing treatments up to 0.92 of the melting temperature and during proton irradiation up to 3 displacements per atom. No significant difference in sizes, compositions and number densities of the nanoclusters was also observed between the unirradiated and proton irradiated conditions. The grain boundaries were found to have high number densities of nanoclusters as well as chromium and tungsten segregation which pin the grain boundary to minimize creep and grain growth.
Study on the Production of Ti Micro-Alloyed High Strength Hot Rolled Steel by CSP Process
Authors: Li Guang Qiang , Xiao Ai Da , Wen De Zhi , Jiao Guo Hua , Zheng Bai Ping , Fu Jie
Published: June 2010

Ti micro-alloyed high strength hot rolled steel was developed in Valin Lianyuan Steel in the CSP line. The cleanliness of liquid steel was good enough for thin slab casting after LF refining. The mould powder was adjusted for stabilizing the heat flux of thin slab continuous casting mould. Homogeneous microstructure consisting of ferrite and pearlite was obtained in the hot rolled steel plates by the improving of rolling process. The nano-scale precipitates of Ti(C, N) and Nb(C, N) is the main strengthening mechanism. The yield strength of developed hot rolled plate is higher than 660 MPa and the tension strength is 760 MPa. The ductile-brittle transition temperature is below -60 degree Celsius. The developed Ti alloyed steel with designed composition fulfils the requirements of 600 MPa grade steel for engineering machinery.
Multiscale Mapping of Mechanical Properties by Instrumented Indentation Test
Authors: Kim Kug Hwan , Kim Young Cheon , Kang Seung Kyun , Kim Kwang Ho , Kwon Dong Il
Published: June 2010

The instrumented indentation test (IIT) is a mechanical testing method to determine the hardness and elastic modulus of materials by putting an indenter into a material surface. This technique has now gone beyond normal hardness tests by evaluating additional properties of materials and by allowing testing at much lower forces and indentation depths (micro/nano ranges). This study presents analytic models and procedures for evaluating tensile flow properties and residual stress state using IIT; the tensile flow properties are treated by defining a representative stress/strain beneath a spherical indenter and the residual stress by using a stress-insensitive contact hardness model. The IIT results are compared with those from conventional methods such as uniaxial tensile test and X-ray diffraction. In addition, IIT can be used as a multiscale mapping tool for the mechanical properties of composite materials and constituent phases by using macro/micro/nano indentation system: we made a hardness map of multiphase steel and measured the strength/residual stress distributions of welded pipeline.
The Fluctuation of Indium Composition in InGaN Based LED Investigated by Atom Probe Tomography (APT)
Authors: Kim Bo Hwa , Gu Gil Ho , Park Chan Gyung
Published: June 2010

In the present study, the relationship between the fluctuation of indium (In) composition and wavelength change involved in internal quantum efficiency of InGaN based LEDs has been investigated. The In composition of commercial InGaN based LEDs with and without annealing at 900 oC has been analyzed by using atom probe tomography (APT). The results revealed that the decrease in In composition caused by annealing at 900 oC for 30 min. exhibited the wavelength change (approximately 6.13 nm blueshift) in the photoluminescence (PL). Wavelength change in the PL of InGaN based LEDs will be discussed in terms of the composition and distribution of In in InGaN/GaN.
Properties of Screen Printed Ceramic Green Films Determined by Optical Laser Profilometry
Authors: Mücke Robert , Menzler Norbert H. , Buchkremer Hans Peter , Stöver Detlev
Published: June 2010

The green density and roughness of green ceramic layers determine their mechanical and micro structural properties after final sintering. These properties can be measured precisely by laser profilometry. The green density of thin layers (20-50 µm) could quickly be determined as accurately as 0.5% theoretical density. The influence of paste parameters (powder conditioning, solid content, binder, and dispersing agent) on the green density was studied systematically for electrolyte pastes (8 mol.-% yttria stabilised zirconia = 8YSZ) typically used in solid oxide fuel cell applications. It could be shown that a minimal binder content is required to achieve acceptable green densities. Pre-calcination of the powder yielded also significantly higher film densities. Dispersant agents contributed to a smoother surface in any case, however a significant effect on the packing density was only observed for the fine, non-calcined powder.
High-Throughput Evaluation of Crystallization Temperature of Pd-Cu-Si System Using Integrated Thin Film Samples
Authors: Aono Yuko , Sakurai Junpei , Shimokohbe Akira , Hata Seiichi
Published: June 2010

In this paper, a new high-throughput evaluation method for crystallization temperature (Tx) of thin film amorphous alloy is introduced. For measurement of Tx on integrated thin film samples, thermography is used. The order of one hundred Pd-Cu-Si thin film amorphous samples with different composition are integrated on one chip and measured their Tx at once. The validity of measured Tx are examined by comparing with results of differential scanning calorimeter that is a conventional method for Tx measurement, and equilibrium phase diagram of Pd-Si. As results, the difference of two methods is within 10 K and the trend of Tx map has strong correlation with the phase diagram, respectively.
Formation and Mechanical Properties of Intermetallic Compounds in Sn-Cu High-Temperature Lead-Free Solder Joints
Authors: Mu De Kui , Tsukamoto Hideaki , Huang Han , Nogita Kazuhiro
Published: June 2010

High-temperature lead-free solders are important materials for electrical and electronic devices due to increasing legislative requirements that aim at reducing the use of traditional lead-based solders. For the successful use of lead-free solders, a comprehensive understanding of the formation and mechanical properties of Intermetallic Compounds (IMCs) that form in the vicinity of the solder-substrate interface is essential. In this work, the effect of nickel addition on the formation and mechanical properties of Cu6Sn5 IMCs in Sn-Cu high-temperature lead-free solder joints was investigated using Scanning Electron Microscopy (SEM) and nanoindentation. It was found that the nickel addition increased the elastic modulus and hardness of the (Cu, Ni)6Sn5. The relationship between the nickel content and the mechanical properties of the IMCs was also established.
Mechanical Properties of Metallized Single Nanofibers
Authors: Kim Hae Rim , Kimura Naotaka , Bang Hyun Sik , Kim Byoung Suhk , Watanabe Yoshimi , Kim Ick Soo
Published: June 2010

We report that the metallized single nanofibers could be successfully prepared by a combined technique of electrospinning and metallization. The mechanical properties of the metallized single nanofibers were investigated by using recently developed tensile test machine. It was found that the metallized single (polyurethane and polystyrene) nanofibers exhibited higher mechanical properties depending on the thickness of the deposited metal layers. For instance, compared with pure PU single nanofibers (Young`s modulus ca. 170 MPa), Young`s modulus for the metallized PU single nanofibers with Cu layers of 30 nm and 50 nm were increased to ca.610 MPa and ca.750 MPa, respectively. Furthermore, the tensile strength of 50 nm Cu-deposited PS single nanofibers (ca. 3.27 GPa) was clearly higher than those of pure PS (ca. 0.76 GPa) and 30 nm Cu-deposited PS (ca. 3.09 GPa) single nanofibers. The results may be attributed to the formation of metallic hard-coating layers onto the surface of single nanofibers.
Rheological Properties of a Particulate-Filled Polymeric Composite through Fused Deposition Process
Authors: Nikzad Mostafa , Masood Syed H. , Sbarski Igor , Groth Andrew M.
Published: June 2010

This paper presents an investigation on rheological properties of a new ABS (acrylonitrile-butadiene-styrene)-Iron composite for application in Fused Deposition Modelling rapid prototyping process. Test samples of ABS-Iron composites have been made by controlled centrifugal mixing and thermal compounding through a single-screw extruder and compression moulding. Rheological characterization was conducted using a capillary rheometer by measuring pressure drop at the die while varying the extrusion speed. Apparent shear rate and shear stress as well as viscosity of the melts were calculated. Modulated differential-scanning calorimetry (MDSC) techniques were used in order to characterize viscoelastic properties of these newly developed composites materials. Non-Newtonian behaviour of the composite melt has shown to follow a cross model of shear thinning characteristics.
Properties of PH 13-8 Mo Steel for Fatigue Application in Helicopters
Authors: Chan Sunny Lok Hin , Tiong Ung Hing , Clark Graham
Published: June 2010

While many fixed-wing aircraft have adopted damage-tolerant design in recent years, helicopter design is still based predominantly on a safe life approach, in which relatively simple Stress Life (S-N) data underpins the tools used for life prediction. Due to their unique loading, helicopter structures experience a high number of loading cycles as compared to fixed-wing aircraft, and this presents a more challenging fatigue life management problem. To minimise the fatigue damage, the helicopter community tends to design components such that most of the loading experienced falls below the fatigue limit of the selected material. These materials are usually of high strength and have good fatigue properties, although the large number of cycles experienced by some components raises the possibility of fatigue in the “gigacycle” regime where the fatigue limit drops to a new, lower level. This paper discusses the suitability of a high-quality PH 13-8 Mo steel for critical helicopter usage, using a simulated application in Australian service to evaluate its fatigue performance particularly at high R ratio and other properties such as density, corrosion properties and cost in terms of the operational environment experienced in Australian helicopter operations.
A Study of Toughness Degradation in CA6NM Stainless Steel
Authors: Iwabuchi Yoshitaka , Kobayashi Isao
Published: June 2010

The mechanism of toughness degradation during slow cooling in the austenite range was studied in CA6NM stainless steel, 13% Cr-4% Ni soft martensitic stainless steel. The variation of toughness, fracture mode and microstructural features were examined by means of cooling rate and isothermal heating in the austenite range together with chemical composition. Toughness degradation was referred to as the increases of FATT and intergranular fracture when those steels were cooled slowly after austenitizing and isothermally heated in the austenite range. The embrittlement was found to be related the intergranular fracture and the precipitation of carbide along prior austenite grain boundaries. Its fracture surface was characterized by mosaic-like markings when the carbide precipitation got to increase. Reducing carbon, silicon and phosphorus and increasing molybdenum improve the toughness degradation.
Microstructure and Mechanical Properties of High Strength Brass Alloy with Some Elements
Authors: Atsumi Haruhiko , Imai Hisashi , Li Shu Feng , Kousaka Yoshiharu , Kojima Akimichi , Kondoh Katsuyoshi
Published: June 2010

The purpose of this research is the development of a high strength α-β brass (Cu-40Zn) with additions of elements of small solid solubility in brass. Cu-40Zn with 0.6 wt.% Tin (Sn), 0.73 wt.% Chromium (Cr) and 0.51 wt.% Iron (Fe) were prepared by casting (Cu-40Zn-CrFeSn). The yield stress (YS) and ultimate tensile stress (UTS) of extruded Cu-40Zn-CrFeSn was 291 MPa and 601 MPa, 23 % and 36 % higher than that of extruded binary Cu-40Zn alloy. Vickers micro hardness of 158 Hv was higher than that of extruded Cu-40Zn alloy (131 Hv). In addition, the elongation of extruded Cu-40Zn-CrFeSn was 35 %. The strengthening mechanisms of these alloys were considered as follows; one was a solid solution strengthening of Cr, Fe and Sn additives which were identified by SEM-EDS. The other was increasing of the area ratio of β-phase in Cu-40Zn-CrFeSn, compared to that of Cu-40Zn.
Tensile Properties of Processed FDM Polycarbonate Material
Authors: Masood Syed H. , Mau Kalpeshkumar , Song W.Q.
Published: June 2010

Knowledge of the mechanical properties of parts processed by Fused Deposition Modelling (FDM) rapid prototyping process is essential for engineering applications of such parts as the mechanical strength of parts depends heavily on the FDM process parameters selected during part fabrication. Little knowledge is available for the Polycarbonate (PC) material used in the FDM systems. This paper presents results of the experimental work on the effect of the FDM process parameters such as air gap, raster width, and raster angle on the tensile properties of PC. Results show that FDM made parts have tensile strength in the range of 70 to 75 % of the moulded and extruded PC parts. The results will be valuable for different functional applications of FDM produced parts and assemblies.
Effects of Deformation-Induced Heating on Bond Strength of Rolled Metal Multilayer
Authors: Yang Deng Ke , Hodgson Peter , Wen Cui'e
Published: June 2010

The bond strength of various metal multilayers produced by cold rolling of metal foils with different thermal conductivity was investigated. Results indicated that under the same conditions of deformation and surface preparation, the metallic multilayer system with low thermal conductivity exhibited relative high bond strength while high thermal conductivity metal system may fail to be roll-bonded together. The relationship between the deformation-induced localized heating and the bond strength were discussed. The deformation-induced localized heating in the low thermal conductivity metal multilayer systems may provide opportunities for achieving a successful accumulative roll bonding or a “cold roll/heat treatment/cold roll” process to synthesize metallic multilayer materials.
Characterization and Properties of Recycled Cellulose Fibre- Reinforced Epoxy-Hybrid Clay Nanocomposites
Authors: Alamri Hatem , Low It Meng
Published: June 2010

In this paper, epoxy eco-composites reinforced with recycled cellulose fiber (RCF) and nano-fillers such as nano-clay platelets (30B) and halloysite nanotubes (HNTs), have been fabricated and investigated. The influences of RCF/nano-filler dispersion on the microstructure, physical and mechanical characteristics have been characterized. Results indicate that flexural strength decreased for the majority of study samples due to the poor dispersion of nano-fillers and the existence of voids within the samples. In contrast, impact toughness and fracture toughness were improved for all reinforced samples. The effect of water absorption was positive in terms of enhancing the impact toughness of the composites. Addition of nanoclay was found to increase the porosities of all nanocomposites.
Strength & Stiffness Estimation for Center Frame of Low-Floor Vehicle
Authors: Kim Yeon Su
Published: June 2010

For the designed center frame of low-floor vehicle to have light-weight sandwich structure with glass fabric/epoxy resin skins, aluminum honeycomb cores and steel inner-frames, regression equations for maximum equivalent stresses (Von-Mises stress) and maximum vertical deflection were proposed by finite element analysis. On the basis of the analysis results, the strength and stiffness for the center frame were discussed in this paper.
Design of a Composite Side Beam for the Railway Bogie Frame
Authors: Kim Jung Seok , Yoon Huk Jin , Shin Kwang Bok
Published: June 2010

This study explains the design, manufacturing and test results for a composite side beam. It has been developed to be applied to the railway bogie frame. The bogie frame is a most important component for safety of a railway vehicle. In this study, the dimensions and stacking sequence of the composite beam has been determined by parametric study and manufactured using autoclave curing. It was tested under static loading conditions of 140kN and 182kN to evaluate structural safety and stiffness. In addition, the nondestructive test using radiograph was performed to investigate the internal damage of it before and after the test.
Composite Filler Metals for Joining Temperature-Sensitive Aluminium- Matrix Composites
Authors: Wielage Bernhard , Hoyer Ina , Weis Sebastian
Published: June 2010

Lightweight composite materials like aluminium-matrix composites (AMC) have been applied in many different sectors such as aerospace industry, automobile production, or power-electronics. As a special group of composites, AMCs produced by ECAE (equal-channel angular extrusion) feature a very high strength due to a very fine-grained structure. But they are very temperature-sensitive. Therefore, an adapted joining technique is required. In this regard, soldering offers some advantages in comparison to other joining processes like welding or bonding. Because of their low melting range below 300 °C, Sn-based filler metals are suitable for this purpose; Ag and Cu are the common alloying elements. The low strength and creep resistance of the joints are disadvantageous features. By the development of Sn-based composite fillers, an improvement of these properties can be achieved due the addition of ceramic reinforcing particles like Al2O3 or SiC. Investigations into the formation of an interfacial reaction layer between reinforcing particles and filler matrix were carried out. Ti as active element was alloyed to improve the bonding between matrix and particles. The microstructure observed by SEM has been correlated with the results of the tensile tests.