bluuebunny/crossref_metadata_2025 huggingface dataset:
High Voltage Breaker Cam Actuator’s Optimization Design on the Virtual Prototype Technology
Authors: Tang Jing Qiu , Cui Yan Bin
Published: October 2009

In this paper, the virtual prototype technology is used for the analyzing and optimizing high voltage breaker actuator’s cam machine. While the high voltage breaker closing, the moving contactor can have the perfect dynamic property by the optimal data. The contactor’s dynamic property curve should be in line with perfect dynamic property curve. The velocity curve can be gotten by analyzing virtual prototype. According to the theory of high voltage breaker’s dynamic property, a smooth voltage curve can be fitted. This fitting curve as the perfect voltage curve can be used for optimizing the cam machine. Supposing other work condition is invariable, the key points on cam profile which decide the dynamic property of the cam machine are analyzed. The coordinates of the key points are optimized and the cam profile is amended. Analyzing the dynamic property of the breaker’s virtual prototype with the amended cam machine, the contactor’s dynamic property curve is perfect. In this paper, the optimal coordinates of the key points are used on the cam profile, and the high voltage breaker actuator’s cam machine is optimal.
Dry Hearth Melting Furnaces
Authors: Newman Peter
Published: October 2009

This paper outlines various aluminium melting furnaces arrangement alternatives and their related benefits as well as the physical and practical challenges of the aluminium melting process using fuel fired reverberatory furnaces. Performance comparisons are made between dry hearth and wet hearth furnaces to highlight the benefits of dry hearth melting as well as the impact of melting practice on ultimate equipment performance. Both single chamber and twin chamber dry hearth furnaces are described in various configurations including the unique benefits of each design.
The Benefits of Forced Circulation for Aluminium Reverberatory Furnaces
Authors: Campbell Paul
Published: October 2009

The benefits of circulating molten metal in an aluminum reverberatory furnace are well documented and include higher productivity, reduced fuel consumption, and excellent metallurgical and temperature homogeneity. Forced circulation can be provided by many different means, but two of the most popular are mechanical and electromagnetic pumps. This paper discusses each benefit in detail to allow the reader to better understand how they are achieved by the use of pumps.
The Use of Electromagnetic Fields for the Detection of Inclusions in Aluminium
Authors: Poynton Steve , Brandt Milan , Grandfield John F.
Published: October 2009

Management of inclusions is an important part of quality control within the aluminium cast house. Inclusions have a detrimental effect on many aluminium cast products. The ability to reliably detect inclusions in a timely fashion is an essential part of this process. There are a number of tools available for inclusion measurement based on different principles. Techniques for inclusion detection such as metallurgical analysis, K-Mold, Podfa, Lais, Prefil all have a delay before detailed results are available. Ultrasound provides a possible technique for an online sensor, however has not as yet managed sufficient sensitivity. LiMCA, based on the Electrical Sensing Zone, has provided the most sensitive online detection to date, but other electromagnetic techniques such as a multiple voltage array sensor offer promise of a sensor which can be built for lower cost and can sample a larger portion of the melt.
Billet Sump Modification of Al-Billets for the Prevention of Starting Cracks
Authors: Rosefort Marcel , Koehler Thomas , Koch Hubert
Published: October 2009

Depending on the cast alloy, starting cracks are a common problem while casting aluminium extrusion billets. Hot crack formation is well investigated in theory as well as the formation of the sump shape using different casting technologies. Nevertheless, starting cracks are a problem in DC casting.
Because TRIMET ALUMINIUM AG Essen uses the spout and float technology for DC-casting of aluminium this paper presents an investigation into methods for the prevention of starting cracks in Al-billets using float and spout DC-casting and covers the research methods, the results of crack prevention and the results of implementing these methods. The main topics to be considered are the control of sump formation and the correlation between sump geometry and hot cracks in the billet.
Our experimental research covers DC-casting with varied casting parameters (stop-and-go casting, casting speed etc.), sump depth measurements, ultrasonic tests and metallographic examinations. We discuss crack prevention in the analysis and interpretation sections given consideration of the sump depth measurements. On the basis of these measurements the effect of the different casting technologies and parameters are shown.
Finally, the methods we describe have to be implemented in production. The essential points are the upscaling and the automation of the casting process, especially the start-up phase.
The results of this investigation provide excellent possibilities for crack prevention for DC-casting.
New Billet Mould Casting Technology
Authors: Emes Chris , Collins Richard J.
Published: October 2009

The aluminum billet casting industry is continually looking for reliable, simple and efficient ways to produce high quality, aluminum billet stock for the extrusion and forging industry. Current demands for billet quality requires that the billet have a very thin inverse segregation of less than 250 microns, uniform cell size of less than 30 microns depending on the alloy, average grain size of less than 130 microns, dendrite arm spacing of less than 50 microns and is crack free. The characteristics of the mould technology needed to achieve the required metallurgical quality economically are described in this paper.
Recent Developments in Australian Aluminium Casthouse Personal Protective Clothing
Authors: Lee Michael
Published: October 2009

Abstract
With the recent release of the Victorian WorkSafe Authority Foundries Compliance Code [1] it is appropriate that Australian Aluminium cast houses, die casting shops and foundries review the status of their personal protective clothing/ equipment (PPE) and practices. Since the issuing of the Foundry Code of Practice [2] in 1986 and the issuing of the new Compliance Code in September 2008 there has been a significant change in the range of PPE utilised in cast houses. This change has been brought about as a result of the advancement in the design and development of the materials used, extensive industry experience and collaboration. The choice of appropriate PPE is also guided by the range and impact of injuries sustained in cast houses. This paper aims to highlight the number of PPE advancements and range of experiences gained between the writing of the Foundry Code of Practice and Foundry Compliance Code as well as to serve as a reference for future improvements for the protection of cast house personnel.
Macrosegregation Mechanisms in Direct-Chill Casting of Aluminium Alloys
Authors: Eskin Dmitry G. , Katgerman Laurens
Published: October 2009

This review paper summarizes the results of recent studies on different mechanisms of macrosegregation upon direct-chill (DC) casting of aluminium alloys. In general, the main mechanisms of macrosegregation have been identified quite some time ago as thermo-solutal convection, free-moving crystals, shrinkage- and deformation-induced flow, and forced convection. Despite this general knowledge, the separation of the effects of these mechanisms on the overall macrosegregation pattern and the ratio of their contribution remained largely unexplored. With the advances in computer simulations and in experimental techniques it becomes possible to look at the impact of individual mechanisms in relation to the macroscopic parameters of the transition region of a DC cast billet and to the microscopic parameters of billet structure. Our systematic research helps in interpreting the apparently contradictory experimental macrosegregation profiles reported in literature. Paper is illustrated by own experimental and computer-simulation results.
Organic Coatings to Prevent Molten Metal Explosions
Authors: Lowery Alex W. , Roberts Joe
Published: October 2009

Over 60 years ago the first reported molten metal explosion from a bleed-out during direct chill casting in an aluminium mill was reported. Soon thereafter, testing was performed to determine the root cause of the explosion.
Upon determination of the root cause, an investigation to determine if any preventive measures could be instituted to prevent the explosions was conducted. Results found that a specific organic coating (e.g., Wise Chem E-212-F) prevented molten metal explosions, whereas some specific organic coatings initiated the explosions.
Fifteen years ago the U.S. Department of Energy in conjuncture with the Aluminum Association reinvestigated the root cause of molten metal explosions. Testing revealed that an initiation or trigger had to be present for a molten metal explosion to occur. Testing identified three additional coatings that could afford protection.
The Supply of Casthouse Equipment and Empowerment of Knowledge to Cast Aerospace Alloys the Almex Way
Authors: Hamer Shaun
Published: October 2009

For well over a decade, Almex USA Inc. has been supplying hard alloy casting technology to the aluminum industry. Today, customers on five continents produce 2000 and 7000 series aluminum billets using this technology in sizes ranging from 75mm through to 1080mm in diameter. In order to produce such a range of sizes in hard to cast alloys and to aerospace standards, Almex has imparted complete casthouse process understanding and know-how, along with equipment supply to its customers. This paper provides an overview of Almex’s hard alloy casthouse technology and describes some of the critical parameters which must be controlled throughout the process route in order to produce defect free alloys for forging, extrusion and flat rolled applications. Explanation is also made of the microstructural requirements of the as cast product and how these influence the final product; along with the range of quality control solutions supplied by Almex to ensure these requirements are met on a continuous and repeatable basis by Almex’s technology users.
DC Casting Using a TF Combo Bag: 3D Modeling of the Distribution of Molten Metal and Heat Transfer
Authors: Tremblay Sylvain P. , Arsenault André , Larouche Daniel , Ilinca Florin , Hétu Jean François , Dubé Jean Philippe
Published: October 2009

In the past 3 years, Pyrotek in association with Laval University and the Industrial Materials Institute of the National Research Council of Canada has developed a simulation package proposing a unique approach in the fluid flow calculation of molten aluminum distribution with a combo bag in the ingot head of sheet casting. This paper will summarize the difficulties encountered and the solutions that were adopted to render that simulation tool efficient and consistent.
Validation of the model using actual casting tests will be detailed as well as the major change in the simulation package in order to obtain decent calculation times. Some examples of simulations will be given to demonstrate that the initial goal of this project has been achieved by the development of a mathematical simulation tool to design and improve metal distributors used in the sheet casting production.
Safety Enhancement in Ingot Casting at Tomago Aluminium
Authors: Nguyen Vu , Grandfield John F. , Rohan P. , Todd B.
Published: October 2009

Tomago Aluminium experienced problems with the boiling of cooling water in ingot casting machines, where water splashed onto molten aluminium after mould filling. The boiling problem was particularly severe when new standard moulds were installed.
This paper describes the experiments and modelling employed to analyse and identify the cause of the problem and based on the results, modifications to mould geometry were suggested. Subsequent testing in lab and field trials showed that the boiling was suppressed. The first set of modified moulds in service at Tomago Aluminium showed mould life was improved as predicted. Other issues with the modified mould design, which arose in service, are also discussed.
Aluminium Bahrain - Benefits at ALBA from Use of Improved Graphite Rings for Production of Extrusion Ingots
Authors: Kadhim Mohamed Ali , Ghuloom Hussain Al Ali Jalal , Martin Garry , Jacobs Michael
Published: October 2009

Surface quality and metallurgical characteristics of extrusion ingot have a significant impact on the extrudability of the billet.
Both the type of casting mould and mould maintenance significantly influences billet surface quality. ALBA, like the majority of extrusion ingot producers, uses moulds with graphite technology, where a mix of oil and gas is injected through a graphite ring into the mould to improve billet surface quality.
ALBA has a policy of continual improvement in the areas of safety, product quality and productivity to enhance customer satisfaction. During 2008, an extensive campaign was conducted in ALBA’s casthouse to select the optimum type of casting rings for Airslip™ moulds supplied by Wagstaff Inc. The graphite casting rings evaluated must be suitable for the casting conditions and environment within the casthouse at ALBA.
This paper details the methodology and the criteria set for the selection of the optimum graphite casting ring type as well as the results achieved. The results of the work showed a preference for L type casting rings, which enhance the quality of the extrusion ingots and extend the service life of the graphite ring.
Greenhouse Emissions in Primary Aluminium Smelter Cast Houses - A Life Cycle Analysis
Authors: Koltun Paul , Tharumarajah Ambavalavanar , Grandfield John F.
Published: October 2009

The aluminium industry is reducing its carbon dioxide emissions and environmental footprint. In order to identify and prioritise areas in the cast house where greenhouse gas emissions can be reduced it is necessary to quantify CO2e (CO2 equivalent tonnes) emissions for the various cast house operations. In this study two typical cast house layouts are examined. In one case, 22kg 99.85% aluminium remelt ingots are produced using chain conveyor ingot casting machines. In the second case, wrought alloy extrusion and rolling slab direct chill cast products are made. Both plants are sized at 500ktpa. The various process inputs in terms of energy and materials were identified and typical usage rates assigned. The results show that general electricity consumption, dross generation and furnace energy consumption are the three biggest areas of CO2e and should be targeted for improvement. Magnesium consumption also has a large effect in the case of the
A Historical Review of the Developments in Casthouse Technology and a Peek into the Future
Authors: Whiteley Peter
Published: October 2009

Over the past thirty (30) years or so aluminium casthouse technology has been driven by a number of factors which have variously included:
• Competition from alternative materials
• Lightweighting
• Market requirements for enhanced properties affecting gas levels, impurities, inclusions, physical and chemical properties, ease of downstream processing, reduced cost and improved delivery
• Reduction in conversion cost by various means including capacity creep, maximising asset utilization, minimizing scrap, reducing melt loss, labour, and energy costs
• The ever present need for improved safety performance.
This paper will explore how these, and related considerations have provided the stimulus for improved casthouse technology which has included developments in hardware, software and culture.
Predicting Dross Formation in Aluminium Melt Transfer Operations
Authors: Taylor John A. , Prakash M. , Pereira G.G. , Rohan P. , Lee Michael , Rinderer Barbara
Published: October 2009

Aluminium melt transfer operations can lead to significant amounts of dross formation as a result of chemical oxidation and physical entrapment processes. It has been suggested that these activities may contribute up to 50% of the total metal loss of ~1% in a typical primary aluminium smelter (i.e. 2,500 tonne/annum (tpa) in a smelter of 500,000tpa output). This is a large financial loss to any company, and also, in the new CO2-conscious era, it also represents a significant carbon footprint to ameliorate. A significant proportion of this metal loss may be prevented by adopting more efficient melt transfer strategies that reduce splashing and turbulence thereby resulting in reduced oxide and therefore dross formation. Optimisation of such systems is normally achieved by trial-and-error approaches, however a clear opportunity exists for rapid optimisation by employing computational modelling to explore the effects of changed equipment design and process conditions, such as tilt speed, spout height, spout geometry, etc. In the present paper, the Smoothed Particle Hydrodynamics (SPH) modeling method is used to predict the amount of oxide generated during molten metal transfers from a 500kg capacity tilting crucible furnace into a heated sow mould. Various conditions were tested. An oxidation model based on skimming trials performed in a laboratory-scale (8kg) oxidation rig is employed in the simulation. The predicted oxide from the simulations is compared against those of the experimental pours. It is anticipated that the validated model will be used for modifying the design and optimizing the operation of various melt transfer operations occurring in the aluminium industry.
Furnace Operations to Reduce Dross Generation
Authors: Peel Alan , Herbert James , Roth David , Collins Martin J.
Published: October 2009

While it is generally acknowledged that dross generation should be kept to a minimum, too often, the importance of maximising the aluminium content of the dross is overlooked. Some mistakenly believe that a low metal content is a good thing and that the aluminium is being kept in the furnace. In reality, this metal is most likely being lost due to insufficient cooling and thermiting.
Much can be gleaned from looking at the dross that is generated in a casthouse; in fact, the quality of dross can provide a good indication of the overall efficiency of the operation. Even with the very low aluminium prices of today, of circa. US$1400 per tonne, a reduction in dross generation within the furnace can provide huge savings per year. Effective dross management also results in better metal quality, improved fuel efficiency, prolonged refractory life and improved yield in the entire facility.
This paper will look at how dross is generated within the furnace in the first place, followed by ways to minimize the dross generation within the furnace using continuous and sub-surface circulation which can also provide significant energy and CO2 reductions. A separate paper will discuss dross processing options and possibilities.
In summary, by careful attention to the equipment and process techniques around the furnace and the follow-on dross management significant cost savings and environmental benefits can be realized by cast house operations.
Automated Metal Siphoning and Cast House Energy Consumption
Authors: Locatelli Jerry , Liu Guang Wei
Published: October 2009

The transfer of molten aluminium from the potline crucible to the holding furnace is receiving renewed attention as pressure to reduce energy wastage in the form of dross is heightened by the prospect of Emissions Trading. Siphoning has long been recognised as the most loss efficient method of metal transfer and now with the availability of fully engineered, automated systems which are safe and reliable in addition to reducing melt loss by 75%; this method is set to become the industry standard. This paper presents some examples of automated siphon transfer systems and demonstrates the benefits of siphoning in applications ranging from the largest smelters to the smallest of foundry applications.
Technological Researches Concerning a Decrease in the Losses Due to the Oxidation of Remelted Scrap from Aluminium Alloys
Authors: Butnariu Ilie , Butnariu Ioana , Butnariu Dana
Published: October 2009

The present paper refers to the remelting of light waste. The research aims to provide a substantial decrease of the oxidation losses and a decrease of the noxious expulsion resulting from the production of aluminium alloys.
The fundamental solution found consists in achieving a stable flux layer. For this the wastes are introduced directly in the metallic bath, without a previous preparation.
Data about oxidation losses, the content of gases and the correlation between the casting properties and the quality of remelting secondary alloys are presented.
Several samples are analysed in order to point out the quality of the alloy and the relationship between the chemical composition, the content of gases and the free linear contraction of the alloy.
Furnace Operation: “A Gold Mine in your Casthouse”
Authors: Girard Guillaume , Barresi J. , Dupuis C. , Riverin G.
Published: October 2009

Scrap rate, throughput, alloy recovery and raw materials are all areas of the casthouse which usually get substantial attention as means of either increasing profits or reducing costs. However, furnaces, which are often overlooked by the casthouse, can also deliver surprisingly high savings. Moreover, these potential savings can only magnify as energy costs and pressures to reduce carbon footprint increase. This paper gives an insight into where savings can be achieved by a casthouse with proper furnace operation. Knowledge of how a furnace should be operated is often neglected but as this paper tries to highlight, developing this knowledge can be extremely worthwhile.
Homogenization Aspects, Continuous versus Batch in an Integrated Modern Casthouse
Authors: Niedermair Franz
Published: October 2009

Continuous homogenizing for extrusion billets has become the accepted standard and state of the art technology. Hertwich Engineering (HE) has, to date, built more than 120 such plants worldwide, which are processing some two thirds of the worldwide extrusion billet production.
Batch type homogenizing is still the best suited technology for various alloys which require long holding times, e.g. 4 – 12 hours, as well as for large-only log diameter production. Again, HE has in recent years supplied several batch homogenizing plants.
Topics:
• Process technology, heating, holding, different types of coolers
• New log support saddle design, exit car, no rolling of logs with focus to good billet surface finish
• Automated sawing, packing
• High efficiency batch furnace and cooler with reversing air and precise temperature regime
Hydro Casthouse Reference Centre
Authors: Furu Trond , Steen Idar Kjetil
Published: October 2009

Since October 2006 the Hydro Casthouse Reference Centre has been operating. The centre is a full scale state of the art pilot casting centre for extrusion ingot, sheet ingot and foundry alloys, consisting of a 17Mtons furnace with a metal loop, a launder system including modular in-line melt treatment units such as ceramic foam filters (CFF) and inline melt refining units (Hycast SIR) and a casting pit with the possibility to cast full size geometries and a casting length of 5.5m. A two strand horizontal casting machine further adds the possibility of continuous casting of extrusion ingot and foundry alloy ingot. The centre has a state of the art superior control system (SCS) and a lay-out, including control room facilities, well suited for training and demonstration purposes. In addition the centre has access to state of the art software codes for simulating the casting process (Alsim) and the as cast microstructure (Alstruc).
The present paper gives some examples on how the centre is operating and the support that is offered to casthouses in Hydro. This includes (i) simulation of the casting processes (hot tearing and as cast structures) applying the Alsim and Alstruc codes, (ii) pilot scale testing of casting and melt treatment equipment, (iii) testing of new parameters and procedures for melt treatment and casting (iv) production of trial orders of new alloys and (v) practical training of casthouse operators (basic for molten metal handling, emergency situations and response, casting principles and trouble shooting, etc.).
Three Dimensional Modeling of Inclined Surface Cracks in FGM Coatings
Authors: Kosker Sadik , Dag Serkan , Yildirim Boray
Published: October 2009

This study presents a three dimensional finite element method for mixed-mode fracture analysis of an FGM coating-bond coat-substrate structure. The FGM coating is assumed to contain an inclined semi-elliptical crack at the free surface. The trilayer structure is examined under the effect of transient thermal stresses. Strain singularity around the crack front is simulated by utilizing collapsed wedge-shaped singular elements. The modes I, II and III stress intensity factors are computed by applying the displacement correlation technique and presented as a function of time. Four different FGM coating types are examined in the parametric analyses which are metal-rich, ceramic-rich, linear variation and homogeneous coatings. The results provided illustrate the influences of the FGM coating type and crack inclination angle on the transient behavior of the mixed-mode stress intensity factors.
Numerical Simulation of Mixed-Mode Crack Propagation in Functionally Graded Materials
Authors: Ma Li , Wang Zhi Yong , Wu Lin Zhi
Published: October 2009

This paper addresses the numerical simulation of mixed-mode crack propagation in Functionally Graded Materials (FGMs) by means of eXtended Finite Element Method (XFEM), endowed with elastic and toughness properties which gradually vary in space. The method allows to follow crack paths independently of the finite element mesh, this feature is especially important for FGMs, since the gradation of the mechanical properties may lead to complex propagation paths also in simple symmetric tests. Each step of crack growth simulation consists of the calculation of the mixed-mode stress intensity factor by means of a non-equilibrium formulation of the interaction integral method, determination of the crack growth direction based on a specific fracture criterion. A specific fracture criterion is tailored for FGMs based on the assumption of local homogenization of asymptotic crack-tip fields in FGMs. The present approach uses a user-defined crack increment at the beginning of the simulation. Crack trajectories obtained by the present numerical simulation agree well with available experimental results for FGMs. The computational scheme developed here serve as a guideline for fracture experiments on FGM specimens (e.g. initiation toughness and R-curve behavior).
The Effective Conductivity of Multiphase Composites with Imperfect Thermal Contact at Constituent Interfaces
Authors: Zhang M. , Zhai Peng Cheng , Zhang Qing Jie
Published: October 2009

This paper studies the effective thermal conductivity of multiphase composite in which a thermal boundary resistance exists at constituent interfaces. Based on the theoretical framework of conductivity for binary system composites in the presence of a thermal contact resistance between matrix and inclusion given by Y. Benveniste and T. Miloh (1986), the fundamental concept is generalized for the case of multiphase composites with imperfect contact which permits a temperature discontinuity between matrix and inclusions of different phases. A micromechanics model, the “generalized self-consistent scheme (GSCS)” based on a particle-matrix embedding in the effective medium, is generalized to evaluate the effective conductivity of multiphase medium with imperfect thermal contact at constituent interfaces. Numerical results are given for three-phase particulate composites with spherical particles to illustrate the effect of imperfect interfaces on the effective thermal conductivity of multiphase composites.
Synthesis and Properties of Graded Porous Ti-TiO2 Multifunctional Composites Obtained by Different Processing Methods
Authors: Bouazza Sofiane , Fuchs Elke , Rosin Andreas , Willert-Porada Monika
Published: October 2009

Functionally graded materials for load bearing implants have a long history of academic development and an already high degree of maturity. Efforts are now undertaken to improve the biocompatibility and even induce bioactivity within the implant-bone interface by optimised surface nanostructure of porous ceramic and metalic layers grown or sintered on a metallic implant, in order to arrive at cementless implants capable of fast osteointegration and high interface strength. Several new methods for surface structure and composition modification are presented for Ti-alloy based implants: a nano-structuring of the surface by re-deposition of TiO2 using an ECR-Microwave Plasma treatment combined with ion bombardment on a sintered TiO2 ceramic surface, a multiscale modification of porous Ti-coatings by means of Micro-Arc-Oxidation, MAO, and a meso-structuring of the surface by means of a laser treatment. The goal is to establish a multi-functionality in such materials by formation of a morphological and compositional gradient spanning many dimensions. The applicability of these methods to real implants is discussed for a dental implant.
The Effect of Particles' Size on the Plastic Behavior of Particles Reinforced Metal Matrix
Authors: Liu Li Sheng , Cao Dong Feng , Mei Hai , Zhang Qing Jie
Published: October 2009

The size effect on particles reinforced metal matrix composites (MMCp) was investigated by a numerical method. A numerical multi-particles unit cell model has been constructed to carry out numerical analysis. In this model, circle particles were randomly placed in matrix according to uniform distribution, the sizes of particles in the paper were classified into 4 groups: 6μm, 13.5 μm ,50μm, and 100μm respectively. For investigating the effect of particles’ size on the plastic behavior of MMCp, the Griffith fracture criterion and the damage of ceramic particles were considered. Result showed that there was a close relationship between the particle size and the deformation behavior of the composites. Yield strength and plastic work hardening rate of the composites increase with decreasing particle size. The predicted stress–strain behaviors of the composites were in agreement with the experimental results.
Dynamic, Modal and Wave Propagation Analyses of 3D Functionally Graded Continua
Authors: Anandakumar Ganesh , Kim Jeong Ho
Published: October 2009

Transient dynamic behavior of a three-dimensional (3D) homogeneous cantilever beam under sinusoidal loading at the free end is verified using the finite element method (FEM). Explicit central difference technique is used for the time integration of finite elements. The tip displacement and maximum stress at the fixed end obtained using the FEM agree well with exact solutions. Modal analysis of a functionally graded (FG) 3D cantilever beam is investigated using Rayleigh-Ritz (RR) method and the FEM. The natural frequencies obtained using the RR method converges as the number of terms in the assumed base function increases. The natural frequencies vary considerably with the gradation of the beam, more for lower modes than for higher modes. Wave propagation in a fixed-free 3D bar is studied using the FEM. Axial stress results for the homogeneous bar with zero Poisson’s ratio agree closely with 1D exact solution. For the FG bar, we see that gradation affects stresses considerably more so at the fixed end than at other locations.
Biocompatibility Aspects of NiTi-Based Medical Implants
Authors: Jämsä Timo , Muhonen Virpi , Danilov Anatoly , Tuukkanen Juha
Published: October 2009

Nickel-titanium is a functional alloy currently used in various clinical applications, especially in vascular stents. There is an increased interest in the orthopaedic use of NiTi-based implants. The alloy enables the manufacture of applications of constant load, controllable motion, and minimal invasiveness. NiTi is considered biocompatible and it possesses mechanical properties that make it an especially good candidate for bone tissue surroundings. In our studies, we have investigated the effects of surface properties of NiTi on its biocompatibility. The martensitic phase was shown to have lower biocompatibility of material in comparison with austenitic NiTi. Cellular cytotoxicity increased and cell adhesion diminished on martensite phase. This was observed with both osteoblasts and osteoclasts. Our studies showed that the thickness of the oxide layer does not necessarily enhance the biocompatibility. The surface state of NiTi is strongly affected by thermal oxidation. Surface properties affect the initial adsorption of proteins and other macromolecules onto the biomaterial surface; this in turn impacts the following cellular responses, such as proliferation and differentiation, which are dictated by adhesion to the extracellular matrix components. Since adhesive force is connected to the interaction with the adsorbed molecules, it might be an important factor in the biocompatibility. Sol-gel derived titania-silica surface treatment was observed to increase the bone-implant coating of functional intramedullary NiTi nails. Sol-gel treatment together with the bending force increased the fixation of the implant (osseointegration). These studies indicate that the surface properties of NiTi are important for its biocompatibility.
Various Nanotube Scaffolds for Cell Proliferation
Authors: Watari Fumio , Akasaka T. , Ishikawa K. , Matsuoka M. , Hirata E. , Terada N. , Yokoyama Atsuro , Uo Motohiro , Itoh S. , Yawaka Y. , Suzuki Masato , Takashi N. , Totsuka Y. , Kitagawa Y. , Abe Shigeaki , Rosca I.D. , Kuboki Yoshinori , Bando Yoshio
Published: October 2009

Carbon nanotubes (CNT) and their derivatives with different structure and compositions have unique features. In the present study, cell proliferation was performed on various nanotubes such as single walled CNTs, multiwalled CNTs and imogolite which is nanotubes of aluminosilicate. SEM observation of the growth of osteoblast-like cells cultured on CNTs showed the morphology fully developed for the whole direction, which was different from that extended to the one direction on the usual scaffold. Numerous filopodia were grown from cell edge, extended far long and combined with CNT meshwork. Apatite precipitation in simulated body fluid, affinity for proteins and saccharides, and nanosize meshwork structure with large porosity would be the properties responsible for these cell adhesion and growth. Imogolite showed the similar properties to CNTs. Nanotubes could be the favorable materials for biomedical applications.
Fabrication of Apatite/Titanium Functionally Graded Coating Using Supersonic Free-Jet PVD
Authors: Yumoto Atsushi , Yamamoto Takahisa , Shiota Ichiro , Niwa Naotake
Published: October 2009

Hydroxyapatite (HAp) is very attractive in medical field. The objective of this study is to produce HAp/Ti composite coating with Supersonic Free-Jet PVD (SFJ-PVD). The SFJ-PVD is a technique to deposit nanoparticles with supersonic gas flow and to form a thick coating film. In a gas evaporation chamber, a source material is evaporated to form nanoparticles in an inert gas atmosphere. The nanoparticles are then carried to a substrate in a deposition chamber with an inert gas flow through a transfer pipe. The gas flow is generated by the pressure difference between the chambers and accelerated to the supersonic flow of 4.2 Mach through a specially designed supersonic nozzle. With SFJ-PVD, we obtain a uniform high-density HAp/Ti composite coating. XRD analysis reveals that the composite coating is composed of Ti and HAp. An in-vitro study was carried out to investigate the bioactivity of the HAp/Ti composite coating under simulated body fluid.
Preparation of Functionally Graded Bio-Ceramic Film by MOCVD
Authors: Sato Mitsutaka , Tu Rong , Goto Takashi , Ueda Kyosuke , Narushima Takayuki
Published: October 2009

Functionally graded Ca-Ti-O/Ca-P-O films were prepared by MOCVD. The phases, composition and morphology of Ca-Ti-O and Ca-P-O films changed depending on the molar ratio of each precursors, total pressure (Ptot) and substrate temperature (Tsub). CaTiO3 films in a single phase were obtained at Tsub = 973 and 1073 K. CaTiO3 films prepared at 873 K had a dense and smooth surface, whereas that prepared at Tsub = 1073 K had complicated rough surface with a cauliflower-like texture. The graded texture of CaTiO3 films from columnar to fine grains was advantageous to good adherence for metal substrates. -TCP and HAp films in a single phase were obtained at Tsub = 973 and 1073 K. Both -TCP and HAp films had a dense and smooth surface. The maximum deposition rate of Ca-Ti-O and Ca-P-O films were 44 and 20 m/h, respectively, and several 10 times grater than that of sputtering method. Apatite formation rate strongly depended on the surface morphology of film. Apatite formed after 3 days on the CaTiO3 film, 14 days on the -TCP film and 6 hours on the HAp film in a Hanks’ solution.
Fabrication of Titanium / Biodegradable-Polymer FGM for Medical Application
Authors: Watanabe Yoshimi , Iwasa Yoshimi , Sato Hisashi , Teramoto Akira , Abe Koji
Published: October 2009

Ti and Ti alloys are widely used as metallic implants, because of their good mechanical properties and nontoxic behavior. However, they have problems as the implant-materials, namely, high Young’s modulus comparing that of bone and low bonding ability with bone. There is a need to develop the Ti and Ti alloys with lower Young’s modulus and good bonding ability. In previous study, Ti composite containing biodegradable poly-L-lactic-acid (PLLA) fiber has been fabricated to improve these problems. However, this composite has low strength because of the imperfect sintering of Ti matrix. To improve its strength, sintering of Ti matrix should be completed. In this study, Ti-NaCl composite material was fabricated by spark plasma sintering (SPS) method using powder mixture of Ti and NaCl to complete the sintering of Ti matrix. To obtain porous Ti samples, Ti-NaCl composite were put into hot water of 100 oC. The porous Ti was dipped into PLLA melt in order to introduce PLLA into the pores of porous Ti. Finally, Ti-PLLA composite was obtained, and PLLA plays a role as reinforcement of Ti matrix. It was found that the Ti-PLLA composite has gradient structure and mechanical properties.
Mechanical Properties-Graded Ti Alloy Implants for Orthopedic Applications
Authors: Jung Taek Kyun , Matsumoto Hiroaki , Abumiya Tadasu , Masahashi Naoya , Kim Mok Soon , Hanada Shuji
Published: October 2009

. Low Young’s modulus is attained by controlling phase stability of  (bcc) Ti-Nb-Sn alloys consisting of non-cytotoxic elements, based on experimental results that Young’s modulus decreases with decreasing temperature toward ” (orthorhombic) martensitic transformation start temperature (Ms). Cold groove rolled, metastable  (Ti-35%Nb)-4%Sn alloy exhibits low Young’s modulus of about 40 GPa at 297 K, measured by the free resonance vibration method. This value is much lower than that of Ti-6%Al-4%V and close to that of human cortical bone. By heating one edge of the groove rolled rod to 573 K for 4 h, hardness and Young’s modulus are found to increase significantly at the heated zone and to change depending on distance from the heated zone. The increase in hardness is explained mainly by fine  precipitation and additionally by microstructure refinement through reverse transformation ”→ of deformation-induced martensite. From these results, an advanced stem having high strength at the necked part can be developed for a new artificial hip joint, keeping low Young’s modulus at the distal part implanted in a femur.
Calcium Phosphate Coating on Blast-Treated Titanium Implants by RF Magnetron Sputtering
Authors: Ueda Kyosuke , Narushima Takayuki , Goto Takashi , Katsube T. , Nakagawa Hironobu , Kawamura Hiroshi , Taira M.
Published: October 2009

Calcium phosphate coating films were fabricated on Ti-6Al-4V plates and screw-type implants with a blast-treated surface using radiofrequency (RF) magnetron sputtering and were evaluated in vitro and in vivo. Amorphous calcium phosphate (ACP) and oxyapatite (OAp) films obtained in this study could cover the blast-treated substrate very efficiently, maintaining the surface roughness. For the in vitro evaluations of the calcium phosphate coating films, bonding strength and alkaline phosphatase (ALP) activity were examined. The bonding strength of the coating films to a blast-treated substrate exceeded 60 MPa, independent of film phases except for the film after post-heat-treatment in silica ampoule. When compared with an uncoated substrate, the increase in the ALP activity of osteoblastic SaOS-2 cells on a calcium phosphate coated substrate was confirmed by a cell culture test. The removal torque of screw-type Ti-6Al-4V implants with a blast-treated surface from the femur of Japanese white rabbit increased with the duration of implantation and it was statistically improved by coating an ACP film 2 weeks after implantation. The in vitro and in vivo studies suggested that the application of the sputtered ACP film as a coating on titanium implants was effective in improving their biocompatibility with bones.
Advanced Nanostructure-Controlled Functionally Graded Materials Employing Carbon Nanotubes
Authors: Estili Mehdi , Takagi Kenta , Kawasaki Akira
Published: October 2009

Capability of multiwalled carbon nanotubes (CNTs) to create in-depth gradients in properties and functionalities of conventional materials has been investigated for the first time. Functionally graded material (FGM) concept has also been employed for the first time to bridge conventional materials to their advanced nanocomposites containing a high concentration of CNTs, which is promising for unexplored yet novel structural, electronic and biomaterial applications. In this study, α-alumina ceramics considered as the most challenging case has been used as the matrix. Bulk, layered, nanostructure-controlled, CNT-based, functionally graded α-alumina ceramics have been fabricated employing a recently established powder processing technology. In-depth gradients in microstructure, grain size and hardness have been successfully achieved in alumina ceramic without cracking, delamination or warping, after homogeneous and gradual incorporation of the CNTs within the alumina ceramic matrix. The FGM approach showed promise to successfully bridge conventional ceramics to their nanocomposites containing a high concentration of CNTs.
Reinforcement of Alumina with Surface Modified Carbon Nanotubes
Authors: Yamamoto Go , Hashida Toshiyuki , Omori Mamoru , Kimura Hisamichi
Published: October 2009

Multi-walled carbon nanotube (MWCNT) reinforced alumina composites were prepared by spark plasma sintering using pristine MWCNTs and acid-treated MWCNTs. The effect of acid treatment on the structure and surface potential of the MWCNTs was examined by transmission electron microscopy (TEM) and zeta potential analyzer. It is demonstrated that with the acid treatment of the MWCNTs, we have deliberately introduced nanoscale defects and negatively charged functional groups on the surface of the MWCNTs. The average depths of the defects are typically 4.8-10.8 nm. Mechanical measurements revealed that surface modification of the MWCNTs is effective in improvement of bending strength and fracture toughness of the MWCNT/alumina composites. Only 0.9 vol.% acid-treated MWCNT addition results in 27% and 25% simultaneous increases in bending strength (689.6 MPa) and fracture toughness (5.90 MPa m1/2), respectively.
Fabrication of (Cemented Carbides/Steel) Bilayered Materials by Powder Metallurgy
Authors: Thomazic Aurelie , Pascal Celine , Chaix Jean Marc
Published: October 2009

This paper analyses the effects of five parameters (composition, compaction pressure, heating rate, sintering temperature and duration) on the sintering of a bilayered (cemented carbide/steel) material. Design of experiments is used to reduce the number of experiments and to analyse the results. After sintering, each sample is characterized (difference of shrinkage, shrinkage anisotropy, density and microstructure). Composition, sintering temperature and duration are the three main parameters which control the sintering of bimaterials, their microstructure and the interface quality. The heating rate and the compaction pressure have no significant effect in the tested domain.
Effects of Inhomogenization on Sintering Behavior of Ni/Al2O3 Powder Mixtures
Authors: Shinagawa Kazunari
Published: October 2009

Aiming at the modification of the sinterability of metal/ceramic powder mixtures, the influence of the homogeneity in microstructure on the sintering behavior is examined. Ni/Al2O3 specimens, with ratios ranging from 0/100 to 100/0, are prepared by compaction through two different procedures of mixing and granulating, to change the degree of particle dispersion. The sintering stress and the viscosity of the specimens are measured by sinter-compression tests to consider the sinterability from the viewpoint of both driving force and resistance. The sintering rate of the inhomogeneous compacts, with agglomeration of powder particles, is larger than that of the homogeneous compacts. This is because the viscosity becomes low, but the sintering stress does not change much by inhomogenizing the microstructure.
Manufacturing of Functionally Graded Porous Products by Selective Laser Sintering
Authors: Erdal M. , Dag Serkan , Jande Y. , Tekin C.M.
Published: October 2009

Selective laser sintering (SLS) is a rapid prototyping technique which is used to manufacture plastic and metal models. The porosity of the final product obtained by SLS can be controlled by changing the energy density level used during the manufacturing process. The energy density level is itself dependent upon manufacturing parameters such as laser power, hatching distance and scanning speed. Through mechanical characterization techniques, it is possible to quantitatively relate the energy density levels to particular strength values. The present study is directed towards manufacturing functionally graded polyamide products by changing the energy density level in a predetermined manner. The mechanical properties of the functionally graded components are characterized by means of tensile testing. Both homogeneous and functionally graded specimens are produced and tested in order to examine the influence of the energy density level on the mechanical response and on the ultimate tensile and rupture strengths. Selective laser sintering is shown to possess the potential to produce functionally graded porous specimens with controlled variations in physical and mechanical properties.
Intermetallic Coating Using a 3-Dimensional Micro Welder
Authors: Matsuura Kiyotaka , Mizuta Naoki , Kirihara Soshu , Miyamoto Yoshinari , Yumoto Atsushi
Published: October 2009

The authors have studied a new method of intermetallic coating using a small TIG welder. This method is based on a reaction between small liquid beads produced from very thin metal wire and the substrate metal surface. The authors designed a computer-aided 3-dimensional micro welder (3DMW) for a previous study on freeform fabrication of intermetallics, and have applied it to this study on intermetallic coating. In this study, a predetermined length of thin aluminum wire was fed onto the titanium substrate surface, and a spark was stricken from a thin electrode of a W-Ce2O3 alloy to make a small aluminum liquid bead on the titanium substrate surface and to simultaneously melt a small area of the substrate surface beneath the liquid bead. All process conditions had been programmed beforehand, including the length of the wire feeding per spark, the position of the electrode, electric power, movement of the stage holding the substrate, etc. The liquid bead containing aluminum and titanium rapidly solidified on the titanium substrate surface producing titanium aluminides on it. Repetition of the aluminum wire feeding, the electrode positioning and the spark striking produced a coating layer consisting of sub-layers of TiAl3, TiAl and Ti3Al from the surface side to the substrate side. Vickers hardness and wear resistance of the coated sample were remarkably improved.