bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Phase Transformation of Austenitic 316L Implant Steel during Compression
Authors: Grądzka-Dahlke Małgorzata , Waliszewski J.
Published: March 2009

The present work concerns development of porous materials for medicine applications. The implant alloys should be paramagnetic because of the danger of reaction with blood cells. However, the strain-induced martensitic transformation may take place due to high strain during implants use. The porous samples made of the 316 stainless steel by the powder metallurgy method were investigated. The results of magnetic studies as well as X-Ray diffraction analysis of sintered specimens after compression tests are presented. The changes in magnetic properties of sintered steel were observed as result of mechanical testing, particularly in case of compression with high strain. Whereas, the X-Ray diffraction did not confirm the phase transformation of austenitic steel.
Modification of Sintered 316L Stainless Steel by Addition of Calcium Pyrophosphate
Authors: Grądzka-Dahlke Małgorzata
Published: March 2009

The paper concerns the problem of exploitative composite materials with solid lubrication additions. The goal of the present investigation was to research the composite materials based on 316L stainless steel powders with the addition of calcium pyrophosphate (Ca2P2O7). The diffusion processes of main elements during sintering were analyzed. The influence of volume fraction of additions on structure of composites and their tribological properties were examined. Tribological tests were performed by a special tribometer, which allowed to realize research during the periodically variable motion with low velocity and variable values of pressure. The structure of materials was observed with scanning electron microscope (SEM). The intensive diffusion of main alloying elements brought the segregation of components and appearance of new phases. Changes in the microstructure, particularly the solution of phosphorus in austenite and attendance of phosphides and oxides insertions, had an effect on mechanical properties of materials. The microhardness, yield strength values as well as wear resistance increased considerably with the rise of modifier addition.
Applied Conditions for a Diffusion Electrochemical Method for Surface Streamlines Visualisation
Authors: Noureddine Abdelkader
Published: March 2009

The setup of the surface flow visualisation by electrochemical deposit has given good results in the case of different flow types and in particular in the case of solids in rotation [1- 4]. This technique is based on the mass transfer principle towards a reactive surface electrode on which the studied flow will be visualised.
This visualisation method of the surface streamlines by electrochemical deposit has allowed to understand the flow between a rotating and fixed discs. The inlet phenomenal named edge effects have been clearly seen during the visualization and the theoretical study. The purpose of this study is to precise the wide range from the surface streamlines configurations.
Fundamental Studies on the Transient Stages of Scale Growth in Fe-22 wt.% Cr Alloys
Authors: Fernandez Diaz Laura M. , Zhu Jing , Holcomb Gordon R. , Jablonski Paul D. , Alman David E. , Sridhar S.
Published: March 2009

It is known that additions of reactive elements such as Ce, La or Y improve the properties of protective oxide-scales on Ni and Fe based alloys [ - ] by increasing oxide adhesion, decreasing the transient time until a continuous Cr2O3 layer is formed and decreasing the parabolic rate constant. Nevertheless, the precise roles played by these reactive elements to improve scales and the precise mechanisms by which they are incorporated into the scale during the surface treatment processes are unknown. Although they are believed to be associated with transport properties in the scale, it is not clear how this occurs or why it improves oxidation resistance. This project is aimed to gain understanding of the scale evolution in Fe-22 wt.% Cr alloys at 800 oC in dry air during the transient stage after 15 minutes of oxidation. The effect of La (120 and 290 ppm) and Ce (270 and 610 ppm) additions added during melt-stage processing are investigated. The surface oxidation process was imaged in-situ through a Confocal Scanning Laser Microscope (CSLM) and the results were correlated with post-experiment characterization through FEG-SEM and FIB-SEM combined with 3D reconstruction. The roles of rare-earth oxide particles on nucleation of Cr2O3 and blockage of short-circuit diffusion paths in the oxide scale and underlying metal are discussed.
Influence of Fast Path Diffusion on the Oxidation of Mn Strengthened IF Steels
Authors: Zhang Zuo Tai , Balaji S. , Sohn Ii Ryoung , Ydstie B.E. , Sridhar S.
Published: March 2009

During the in-line coating process of Mn-strengthened-Interstitial-Free-steels, selective oxidation under low dew-point atmospheres may result in surface oxides that are not wetted by the coating alloy. In the current study, we investigate the formation of external and internal oxides in the metal in order to characterize the influence of fast path diffusion. The short-time oxidation in the metal was carried out in a gold-image furnace and the resulting external and internal oxides were characterized through scanning-electron microscopy. An IF steel sample containing 1.5wt.% Mn was used and the effects of dew point (DP) ranging from –75 to –15oC on oxidation was investigated at 800oC by varying the PH2/PH2O ratio in the oxidizing gas. Simulations were carried out by considering the combined effect of diffusion and mass transfer represented by a system of partial differential equations. The model equations were solved using finite element method in a Multiphysics modeling software COMSOL. The experimental and simulated results were found to be in agreement, and showed that, for DP up to –30oC, gas phase mass transport of oxidant gas controls the oxidation which results in exclusively external oxide nodules distributed uniformly on the surface. At –15oC > DP > –30oC, the oxidation evolves as ridges along grain boundaries and the simulations indicate that this is due to solid state diffusion control and the controlling mechanism is fast path diffusion through the alloy. At this point, internal oxides also start to appear.
Influence of Diffusion in the Underlying Metal during Oxidation of Iron Containing Small Amounts of Copper and Nickel
Authors: Webler B.A. , Sridhar S.
Published: March 2009

The residual element copper in recycled steels embrittles grain boundaries, causing a surface cracking phenomenon known as hot shortness. Embrittlement is caused by a copper-rich liquid phase that forms at the oxide/metal interface during steel oxidation. Another residual element, nickel, enriches along with copper and reduces hot shortness cracking. The mechanisms by which nickel affects copper enrichment behavior have not yet been adequately studied. This work examines the effects of nickel and copper on the oxidation behavior and oxide/metal interface microstructure of iron. Iron-0.3 wt% copper alloys containing 0.1 wt% nickel and 0.05 wt% nickel were compared. Pure iron was used as a reference material. Alloy samples were oxidized in air at 1150°C. The parabolic oxidation rates for both alloys were found to decrease by a factor of two from that of pure iron. Both alloys had perturbed oxide/metal interfaces consisting of alternating solid/liquid regions. The interface development is due to stabilization of perturbations in the solid/liquid interface. The interface morphology can also explain the observed decrease in oxidation rate.
Diffusion Transport in Electrochemical Systems: A New Approach to Determining of the Membrane Potential at Steady State
Authors: Filipek Robert , Szyszkiewicz Krzysztof , Bożek Bogusław , Danielewski Marek , Lewenstam A.
Published: March 2009

Ionic concentrations and electric field space profiles in one dimensional membrane are described using Nernst-Planck-Poisson (NPP) equations. The usual assumptions for the steady state NPP problem requires knowledge of the boundary values of the concentrations and electrical potential difference. In analytical chemistry the potential difference may not be known and its theoretical prediction from the model is desirable. The effective methods of the solution to the NPP equations are presented. The Poisson equation is solved without widely used simplifications such as the constant field or the electroneutrality assumptions. The first method uses a steady state formulation of NPP problem. The original system of ODEs is turned into the system of non-linear algebraic equations with unknowns fluxes of the components and electrical potential difference. The second method uses the time-dependent form of the Nernst-Planck-Poisson equations. Steady-state solution has been obtained by starting from an initial profiles, and letting the numerical system evolve until a stationary solution is reached. The methods have been tested for different electrochemical systems: liquid junction and ion selective electrodes (ISEs). The results for the liquid junction case have been also verified with the approximate solutions leading to a good agreement. Comparison with the experimental results for ISEs has been carried out.
Structural Relaxation Process in CuHfTi Amorphous Alloys
Authors: Yamada Kazumasa , Shinagawa N. , Sogame M. , Figueroa I.A. , Davies Hywel A. , Todd Iain
Published: March 2009

The aim of this research is to clarify a quantitative evaluation in the structural relaxation processes focusing on the activation energy in Cu based amorphous alloys. The activation energy for structural relaxation process in a metal type amorphous CuHfTi ternary alloys, with cross sections of typically 0.03 mm x 2.0 mm, prepared by chill-block melt spinning has been investigated by Differential Scanning Calorimetry (DSC) with a cyclically heating technique. Activation energies for structural relaxation with a spatial quantity in amorphous materials have been discussed by use of a relaxed ratio function that depends on annealing temperature and time. In the present work, the distributions for the Activation Energy Spectrum (AES) were observed almost 152 kJmol-1 (1.58 eV). Another result has been also established that the “reversible” AES model energy distribution though the cyclically structure relaxation occurs even in amorphous Cu60Hf20Ti20 alloy.
Concentration Distribution in the Wake of a Plane Surface Buried in a Porous Media in Alignment with the Flow Direction
Authors: Delgado João M.P.Q. , Vázquez da Silva M.
Published: March 2009

The present work describes the mass transfer process between a moving fluid and a slightly soluble flat surface buried in a packed bed of small inert particles with uniform voidage, by both advection and diffusion. Numerical solutions of the differential equation describing solute mass conservation were undertaken to obtain the concentration profiles, for each concentration level, the width and downstream length of the corresponding contour surface and the mass transfer flux was integrated to give the Sherwood number as a function of Peclet number. A mathematical expression that relates the dependence with the Peclet number is proposed to describe the approximate size of the diffusion wake downstream of the reactive solid mass.
Numerical Prediction of the Effective Thermal Conductivity of Perforated Hollow Sphere Structures
Authors: Hossein Hosseini Seyed Mohammad , Merkel Markus , Augustin Christian , Öchsner Andreas
Published: March 2009

This paper investigates the thermal properties of a new type of hollow sphere struc-
tures. For this new type, the sphere shell is perforated by several conical holes in order to open
the inner sphere volume. The effective thermal conductivity of perforated sphere structures in
a primitive cubic arrangement is numerically evaluated for different material combinations and
compared to sphere structures without perforation.
Determination of Boron Diffusion Coefficients in Borided Tool Steels
Authors: Campos-Silva Ivan , Ortíz-Domínguez M. , López-Perrusquia N. , Escobar Galindo R. , Gómez-Vargas O.A. , Hernández-Sánchez E.
Published: March 2009

The boron diffusion in the Fe2B and FeB borided phases formed at the surface of AISI H13 tool steels during the paste boriding process was estimated. The treatment was carried out at temperatures of 1173, 1223 and 1273 K with 2, 4, 6 and 8 h exposure times for each temperature using a 4 mm layer thickness of boron carbide paste over the material surface. The boride layers were characterized by the GDOES technique to determine in quantitative form the presence of the alloying elements on the borided phases. The boron diffusion coefficients and were determined by the mass balance equation and the boride incubation time assuming that the boride layers obey the parabolic growth law. Also, the mass gain produced by both boride layers at the surface of the tool steels was determined. Finally, the boron diffusion coefficients were interpreted as a function of the treatment temperature, obtaining the activation energy values for the diffusion controlled growth of Fe2B and FeB hard coatings.
Diffusion in Nanocrystalline Ion Conductors Studied by Solid State NMR and Impedance Spectroscopy
Authors: Heitjans Paul , Wilkening Martin
Published: March 2009

Materials with an average particle size of less than about 50 nm often show new or at least
enhanced physical properties. In many cases nanocrystalline ionic conductors exhibit a high increase
of cation, e. g. Li+, or anion, e. g. F−, diffusivity. In the present contribution we review recent studies
on ion dynamics in nanocrystalline ion conductors, both single-phase systems and composites, being
prepared by high-energy ball milling. These include, e.g., LiTaO3, Li2O:Al2O3, LiF:Al2O3, BaF2,
CaF2, BaF2:CaF2 and (BaF2:CaF2):Al2O3. Dynamic properties were probed by 7Li and/or 19F NMR
line shape and relaxation as well as ion conductivity measurements.
Stability of Neutral Silicon Interstitials in 3C- and 4H-SiC: A First-Principles Study
Authors: Liao Ting , Roma Guido
Published: March 2009

The structural stability and properties of single silicon interstitials in their neutral state are investigated via ab initio methods in 3C- and 4H-SiC. By carefully checking the convergence with Brillouin Zone (BZ) sampling and supercell size we show that the split interstitial along <110> direction and tetrahedrally coordinated structure have similar formation energies in the cubic polytype. We discuss possible artifacts coming from the well known Density Functional Theory (DFT) underestimation of the band gap, which is particularly relevant for 3C-SiC. For 4H-SiC, the most energetically favorable silicon interstitial is found to be the split interstitial configuration ISisp<110> but situated in the hexagonal layer. The defect formation energies in 4H-SiC are in general larger than those in 3C-SiC, implying that the insertion of silicon interstitial introduces a large lattice distortion to the local coordination environments and affect even the second- or third-nearest neighbors. We also present an extensive comparison between well converged plane waves calculations and SIESTA [1,2] calculations based on localised orbitals basis sets.
Nanostructured Materials Prepared by Mechanical Alloying and Mechanochemical Process
Authors: Shokuhfar Ali , Nasiri-Tabrizi Bahman
Published: March 2009

Mechanical alloying and mechanochemical treatment are the major powder processing techniques on the nano scale. In these processes a high energy ball mill has been applied to synthesize compounds and nanocomposites such as aluminum metal matrix nanocomposite, hydroxyapatite and bionanocomposites based on hydroxyapatite. These processes involve deformation, cold welding, fracturing, and rewelding of powder particles. Due to the applied mechanical forces, chemical reactions and phase transformations could also take place.
In the present research work, the effects of milling time, milling media, and sonication process on the microstructures and morphology of the obtained materials were evaluated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The results indicate that increasing the milling time leads to an increased lattice strain and decreased crystallite sizes. Furthermore, the results show that the sonication process leads to the morphological improvement of nanocrystalline hydroxyapatite. The obtained data show that the nanocrystalline hydroxyapatite with low contamination and suitable morphology can be produced in Polyamide6 vials similar to stainless steel vials, therefore it seems that using polymeric and polymeric based nanocomposite vials with high strength and wear resistance could lead to a new way for the mass production of nanocrystalline hydroxyapatite with high performance, low contamination and low cost.
Mesoporous Bioactive Glasses: Synthesis, Characterization and In Vitro Bioactivity
Authors: Zhao Yu Feng , Ma Jan
Published: March 2009

In this work, two systems of mesoporous bioactive glasses (MBGs) with a series of
different SiO2:CaO:P2O5 ratios were derived via a sol-gel method involving the usage of block
copolymers Pluronic F127 and P123 as templates, respectively. A two-dimensional hexagonal
(P6mm) mesoporous structure was obtained in the two systems with a SiO2:CaO:P2O5 ratio of
80:16:4. With the decrease of the SiO2 content, the porous structure of MBGs became less regular,
and the BET surface area and the pore volume were also decreased. Mesoporous bioactive glasses
from the template F127 displayed a higher degree of bioactivity than those from the template P123,
as a result of the existence of more defects on the walls of the mesopores.
The Effect of Yttria-Stabilized Zirconia on the Properties of the Fluorine-Substituted Hydroxyapatite Ceramics Prepared by Pressureless Sintering
Authors: Chen Y. , Dong Z. , Miao X.
Published: March 2009

Hydroxyapatite-zirconia composites have received much attention during the last decade
due to their combination of the desirable mechanical properties of zirconia and the excellent
bioactivity of hydroxyapatite (HA). However, thermal decomposition of the hydroxyapatite phase and
reaction between the zirconia phase and the hydroxyapatite phase remain a major problem in the
hydroxyapatite-zirconia composites. In this study, thermally stable and fluorine-substituted
hydroxyapatite (Ca10(PO4)6(OH)0.8F1.2; coded as HA06F) was prepared by a sol-gel method to replace
the hydroxyapatite. Yttria-stabilized zirconia (YTZP) was also prepared by a sol-gel method in order
to produce HA06F-YTZP composites with 5, 10, 15, 20, 40, and 60 wt% YTZP by simple and
cost-effective pressureless sintering. Thermogravimetric analysis (TGA) and x-ray diffraction (XRD)
of the HA06F-YTZP composites showed that the thermal stability of the HA06F matrices could be
maintained when the YTZP content did not exceed 20 wt% and for sintering temperatures less than
1400 oC. Dilatometric analysis and microstructural observation revealed that the YTZP phase in the
HA06F-YTZP composites retarded the densification of the composites if the zirconia content was
over 20 wt%. Electron scanning microscopy (SEM) and high resolution transmission electron
microscopy (HR-TEM) of the HA06F-YTZP composites showed that the YTZP second phase had a
size in the nanometer scale and the reaction between the HA06F phase and the zirconia phase was
suppressed. Mechanical properties including the Knoop hardness, the Young’s modulus, and the
fracture toughness of the HA06F-YTZP composites increased with the YTZP content until the
optimal content of 20 wt%; higher YTZP contents led to low mechanical properties due to poor
densification of the composites and the severe thermal decomposition of the HA06F phase. The
optimal HA06F-20YTZP composite also showed desirable attachment and proliferation of osteoblast
cells. Nevertheless, the study of the composite system indicated the limitations of the pressureless
sintering technique. To achieve the full potential of the composites for medium or low load bearing
applications, a pressure-assisted sintering technique would still be necessary.
Modification of Drug Release Profiles of Poly(L-Lactide) Using Palmitic Acid
Authors: Nugraha Bramasta , Tan Lay Poh
Published: March 2009

Palmitic acid was added into drug-loaded poly(L-lactide) (PLLA) to modify the drug
release profiles of the polymer. The acid was added in different concentrations and gradients across
the thickness of the polymer. Drug release was monitored using a UV spectrometer over a period of
90 days. Degradation was studied using gel permeation chromatography and differential scanning
calorimetry (DSC) to follow the change in the molecular weight and glass transition temperature
respectively. Addition of palmitic acid was found to accelerate the degradation of PLLA and
resulted in an accelerated release of the drug as expected. Modification of release profiles by
designing the acid gradient was also attempted. It was found that the total acid concentration is still
the dominant factor over the gradient design in affecting the degradation and subsequently the
release profiles. Different drug concentrations also played a role in the different release profiles
exhibited. Surprisingly the sample with lower drug concentration (2wt%) showed a much higher
initial burst than the 5wt% loaded samples. This was due to the induced nucleation of the polymer
by the drug at low concentration resulting in higher crystallinity of the polymer and consequently
overall lower solubility of the drug.
3-D Self-Assembled ZnSnO3 Nanoparticles: One-Step Solid-State Synthesis
Authors: Zhu Jian Min , Ma G.B. , Li F. , Huang S.S. , Li Q. , Xin X.Q. , Ming Nai Ben
Published: March 2009

By means of solid-state reactions method, ZnSnO3 nanoparticles were prepared in the reactions of ZnCl2 and SnCl4·5H2O with KOH in the presence of added KCl crystal, and were assembled into 3-D aggregates with tetragonal-like shape in the size range of 20-200 nm. The products were characterized by powder X-ray diffraction (XRD), and the microstructures of the samples were investigated by transmission electron microscope (TEM), selected area electron diffraction (SAED) and high-resolution transmission electron microscope (HRTEM) in detail. Probable mechanisms for the formation of such tetragonal-like shape of ZnSnO3 3-D aggregates are proposed.
Characterization of Si Nanocrystals Embedded in SiO2 with X-Ray Photoelectron Spectroscopy
Authors: Liu Y. , Chen T.P. , Fu Y.Q. , Hsieh J.H.
Published: March 2009

X-ray photoelectron spectroscopy (XPS) has been used to characterize the Si nanocrystals (nc-Si) incorporated in SiO2 by ion implantation and subsequent thermal annealing. XPS results suggest that the as-implanted films contain a composition of a few suboxide SiOx (x<2). The dependence of XPS spectra on annealing temperature show that these suboxides decompose into SiO2 and Si nanocrystals. Due to the implanted Si+ depth profile, thermal annealing will lead to the
formation of nc-Si with different sizes corresponding to the depth. Si0 peak shifts arising from the size effect of nc-Si can be clearly observed. Photo-induced charge effect from the nc-Si has been studied in this work. The potential wells induced by nc-Si in the SiO2 band gap substantially enhance the charging effect, which causes a significant shift in Si0 and C1s core levels.
Optical-Property Profiling of SiO2 Films Containing Si Nanocrystals Formed by Si+ Implantation
Authors: Liu Y. , Chen T.P. , Tse M.S. , Ho P.F. , Tan A.L.K. , Liu Y.C.
Published: March 2009

A quantitative approach to determination of depth profiles of optical properties of
Si-implanted SiO2 films based on spectroscopic ellipsometry (SE) is presented. From the SE measurements, the depth profiles of the complex refractive index of SiO2 films containing Si nanocrystals (Si-nc) are obtained with an effective medium approximation (EMA) in the wavelength range of 400-1200nm. The optical profiles obtained imply the existence of a wave-guide in the Si-doped SiO2 films.
Structural and Microwave Properties of Copper Ferrite Nanoparticles Prepared by Sol-Gel Synthesis
Authors: George Thresiamma , Joseph Sunny , Mathew Suresh
Published: March 2009

Copper ferrite nanoparticles are prepared by sol-gel synthesis using polyacrylic acid (PAA) as chelating agent. The crystal structure and surface morphology are studied by XRD and SEM techniques. Microwave dielectric parameters such as real and imaginary part of complex permittivity and a.c. conductivity are determined in the frequency range 2247 - 2970 MHz by microwave cavity perturbation technique. Microwave magnetic parameters such as the real and imaginary part of complex permeability are also determined.
Damping Characterization of Bulk Nanostructured Nickel Using an Innovative Circle-Fit Approach: Effect of Frequency
Authors: Srikanth Narasimalu , Thein Maung Aye , Gupta Manoj
Published: March 2009

In the present study, elemental Ni powder was mechanically milled (MMed) for 10 hours to reduce the grain (crystalline) size in the nano-range (<100nm). The mechanically milled powder (10h-MMed) was consolidated by die-cold compaction and was further hot extruded at high temperatures to maintain a crystallite size within the nano range. Further, the specimen was tested by a novel free-free type suspended beam arrangement, coupled with circle-fit approach to
determine damping characteristics. To vary the resonant frequency of the suspended beam, end masses with different weights were added. The characterization results revealed that the nano-size grains exhibit increased damping compared to a coarse-grained sample, under similar vibration frequency. Results also show that the damping capacity of both nano and coarse grained samples decreases with an increase in frequency of vibration. Particular emphasis was placed to correlate the damping capacity with the process induced residual stresses present in the samples.
Effect of Magnetic Field on the Magnetic Structure of Nanocrystalline Electroplated NiFe Layers
Authors: Li Xiao Ping , Zhao Z.J. , Oh T.B. , Seet H.L.
Published: March 2009

In order to develop high sensitivity micro sensors for bio-magnetic field using NiFe
electroplated composite sensing elements, it is important to study how different plating processes can affect the magnetic properties in terms of the chemical composition and magnetic structure of the plated layer. In this study, to study the effect of the magnetic field on the magnetic structure of the electroplated NiFe layers, magnetic controlled plating in which a longitudinal magnetic field ranging from 0 to 400 Oe is applied during nanocrystalline electroplating of permalloy Ni80Fe20 layer of 2 µm thick onto a 20 µm diameter Cu wire. The magnetic structure of the plated layers is studied by investigating the Giant magneto-impedance (GMI) effect of the plated layer. GMI has been measured from a frequency range of 100 kHz to 50 MHz. It is observed that under conventional electroplating without an external magnetic controlling field, the anisotropy of the plated layer is generally circumferential as indicted by the double peaks of the MI curves in testing at high frequency. When a longitudinal magnetic field is applied during electroplating, the plated layer shows single peak MI curves, suggesting that the anisotropy is changed from circumferential to longitudinal. The results also show that the
sensitivity and resolution of a magnetic field sensor is improved greatly by changing the anisotropy of the plated layer from circumferential to longitudinal.
Effect of Sputtering Target Power on Preferred Orientation in nc-TiN/a-SiNx Nanocomposite Thin Films
Authors: Zhang Sam , Sun Deen , Fu Yong Qing , Du H. , Zhang Qing
Published: March 2009

Nanocrystalline TiN (or nc-TiN) has been imbedded in amorphous silicon nitride (a-SiNx)matrix to form a nanocomposite thin film (nc-TiN/a-SiNx) via magnetron sputtering deposition on silicon wafer. Two important effects of the Si3N4 sputtering target power on the formation of nc-TiN/a-SiNx have been studied: (1) Aside from forming a-SiNx in the matrix, Si atoms also imbed into TiN to form (Ti,Si)N solid solution crystallites. At low target power, the solid solution is substitutional. With increase of power, the amount of silicon “dissolved” in the TiN crystallite increases, and in the meantime, the interstitial components increase which is manifested in the increase in the TiN lattice parameter. (2) The crystallites have a preferred orientation varying with the deposition target power. As conveniently described by the coefficient of texture, the degree of preferred orientation along [111] direction decreases and finally tails off with increase of power. At the same time, the crystallites orient along [200] and [220] direction and eventually [220] direction dominants.
Functionally Graded Nano Hardmetal Materials Made by Spark Plasma Sintering Technology
Authors: Tan Xinglong , Qiu Shaoyu , He Wenyan , Lei Daifu
Published: March 2009

The properties of nano WC/Co hardmetals prepared by different Spark Plasma Sintering processes were measured. A 4-layer Functionally Graded Materials (FGM) was also obtained by Spark Plasma Sintering technology (SPS), starting from powders of nano WC/10%Co, nano WC/12%Co, micro WC/15%Co and stainless steel disk. The other 3-layer FGM was made from powders of nano 21%Al2O3/ZrO2, nickel and stainless steel. The SPS processing led to FGM free of internal stress, which was measured using Vickers indentations.
Microwave Heating of Hydrated Zeolites and Application of Zeolites as a Domestic Reusable Desiccant through its Technique
Authors: Ohgushi Tatsuo , Nagae Mayumi
Published: March 2009

Na-X zeolite easily caused a thermal runaway by microwave radiation of 500W but Ca-X zeolite merely reached ca. 300°C. Mixtures of Ca-X and Na-X reached lower heating temperature with increasing the content of Ca-X and the heating temperature could be controlled (>300°C) by adjusting the content. Since water in X zeolite almost completely desorbs by 400°C, conditions realizing the heating temperature of ca. 400°C were studied. The mixture with the ratio of Ca-X/Na-X=0.9/0.1 was quickly heated to ca. 400°C by the radiation of 10-20 min in the 500 W
power and reached the dehydration state up to >90 %. A degradation degree of adsorption capacity of the mixture for water was examined after two and three treatments with the microwave heating. The average degradation degree was 1.4 % per treatment. The properties of the zeolite desiccant with microwave treatment were compared with those of commercial CaCl2 desiccant. It was found that the
zeolite desiccant is superior to the commercial desiccant and an application of zeolite to a domestic reusable desiccant, through the heating technique, is promising.
Preparation and Characterization of Nano-Scaled Ag Plated Activated Carbon Fibers for NO Removal
Authors: Park Soo Jin , Kim Byung Joo
Published: March 2009

In this work, the catalytic reduction of NO over activated carbon fibers (ACFs)/Ag prepared by nanoscaled Ag electroplating has been studied. It is observed that silver content on ACF surfaces increases with increasing the plating time. However, a decrease of adsorption properties, including BET’s specific surface areas and total pore volumes, in increasing the plating time is observed within the range of well-developed micropore structures. As the experimental results, the net heat of adsorption of the ACFs/Ag samples is largely influenced on the amount of silver metal, and the catalytic ability for NO removal over ACFs/Ag samples is improved in the presence of silver on the ACFs. However, the adsorption properties of the excessively silver loaded samples are significantly reduced, resulting in the decrease of the removal efficiency. Therefore, the NO removal is largely depended on silver content on ACFs, together with the results of adsorption properties of the ACFs.
Preparation and Characterization of nc-(Ti,Al)N and h-AlN Nanocrystalline Deposited by Plasma CVD Techniques
Authors: Moto K. , Veprek Stan
Published: March 2009

As alternative to TiN based material, nc-(Ti1-xAlx)N and h-AlN were deposited on steel substrate using plasma CVD technique and characterized by means of XRD, XPS, EDX. The effect of Al substitution can be shown by the decrease of the lattice parameters of TiN as the fraction of Al increases. As the fraction of Al further increases up to 0.8, the hexagonal AlN phase precipitates. The hardness of these coating are around 30 GPa higher than that prepared by other method.
Processing-Structure Correlations of Ni-Fe-Cu-Cr Soft Magnetic Alloy
Authors: Wei Zhou , Tien Oh Joo , Hoon Hng Huey
Published: March 2009

Nickel-based alloy is an important class of magnetic materials that have high
permeability, large saturation and remnant magnetization, low hysteresis loss and low coercivity. These properties vary with the grain size, shape, magnetic domains and orientation. As the grain approaches nanoscale, an important averaging of the
magnetocrystalline anisotropy over many grains coupled within an exchange length
results in a significant increase of the magnetic softness and the effect of the internal
thermal energy becomes more pronounced. The crystalline Ni-Fe-Cu-Cr system
processed by high-energy ball milling (HEBM) and metal injection moulding (MIM)were investigated using TEM and SEM. The average grain size of the HEBM samples was found to be in the order of several tens of nanometers while those of the MIM are in the order of tens of micrometers. The magnetic properties of the HEBM and MIM samples were also investigated. The magnetic properties of the HEBM samples are significantly ‘softer’ magnetically when compared to the MIM samples. The coercivity (Hc) of MIM sample is 37.5 Oe while the HEBM sample is 17.5 Oe. More remarkably, the initial permeability (µi) of the HEBM sample is an order higher than the MIM sample 2184 and 225 Oe respectively.
Evaluation of Failure Behaviour of Coated Anisotropic Materials for Dental Implants
Authors: Punantapong Boonyong , Thongtem Somchai , Fagan M.J.
Published: March 2009

This paper presents the results of an experimental procedure where a grid is applied to the edge of a specimen and the local crack-tip displacement fields are calculated using finite element technique. Increasingly, the objective of finite element simulations is to predict the response of the mechanics of material failure are related to microstructural process that occur in the materials as a result of the loading conditions. At the same time, The influences of coating thickness, coating stiffness, and assume crack pattern on the stresses concentration between the neighbouring layers of material are evaluated. Consequently, one approach to simulating the response of structures is to explicity model the mechanisms of damage and failure in the material.
Synthesis and Characterization of a POSS-Urethane Hybrid Coating for Use in the Corrosion Protection of Metal
Authors: Oaten Matthew , Roy Choudhury Namita
Published: March 2009

The potential of cyclic silsesquioxanes as flexible coatings has been explored in this work for corrosion protection of metal. A polyurethane coating containing an inorganic polyhedral oligomeric silsesquioxane (POSS) was synthesized and characterized by means of photo-acoustic infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle and modulated differential scanning calorimetry (MDSC). The coating has been applied to clean steel substrates via dip and spin coating. The POSS based hybrid coating is found to be uniform, dense and essentially defect free. XPS shows that the coating forms a lamellar layered structure on the substrate.
Synthesis of a Novel Nanostructure of Rutile Titania by Sonochemical Method
Authors: Ma G.B. , Zhu Jian Min , Ming Nai Ben
Published: March 2009

Chestnut-bur-like rutile titania assemblies are successfully synthesized by a sonochemical method. Scanning electron microscopy and transmission electron microscopy analyses reveal that the assemblies are formed by radial coagulation of rutile acicular nanocrystals. Effects of experimental conditions on the phase and structure of the products are also presented.
Synthesis of Nanocrystalline Tungsten Alloy by Mechanical Alloying and Annealing
Authors: Liu Z.G. , Lu L. , Lai M.O.
Published: March 2009

Formation of partial nanocrystal and amorphous tungsten alloys was synthesized via crystallization of a completely amorphized tungsten alloy synthesized by mechanical alloying. Structural characterization shows formation of amorphous structure from mechanical alloying of a mixture of elemental tungsten and iron powders after about 150 hours. Partial nanocrystalline phases within the amorphous matrix were formed through annealing the amorphous tungsten alloy at 1075°C.
Synthesis of α-Fe2O3 Nanowires and its Magnetic Properties
Authors: Liu Y.W. , Rui X.F. , Fu Y.Y. , Zhang Han
Published: March 2009

a-Fe2O3 nanowire was successfully synthesized by oxidation of pure iron. The
as-synthesized a-Fe2O3 nanowire arrayed normal to the surface of the substrate, were perfect single crystals with diameters of 20 to 40 nm and lengths varying from 2 to 5 µm. The magnetic property of the nanowires was studied, and some interesting phenomena were observed. The magnetic moment of the nanowire shows an antiferromagnetic behavior at high temperature and a weakly ferromagnetic behavior at low temperature. The block temperature of the a-Fe2O3
nanowire was found to be significantly higher than that of a-Fe2O3 nanoparticle.
Ultrasonic Characterization of Silver Nanoparticles
Authors: Rajagopalan S. , Sharma S.J. , Nanotkar V.Y.
Published: March 2009

Nanoparticles exhibit unusual properties in contrast with their bulk properties due
to small particle size and quantum confinement. In the present work, ultrasonic velocity and density measurements have been carried out in solutions of silver nanoparticles in micellar dispersion of cetyl tri-metyl ammonium bromide, CTAB. Ultrasonic velocity measurements at different concentrations of surfactant and temperatures were carried out using Sing-Around technique, operated at 2MHz. It is observed that ultrasonic velocity and adiabatic compressibility show abnormal behaviour with increase in concentration of CTAB in the solution, indicating the existence of the phase separations in nano-colloidal solution.
Low-Temperature Growth of Large Area, Vertically Aligned Carbon Nanotubes for Field Emission Applications
Authors: Tsakadze Z.L. , Ostrikov K. , Storer R. , Xu S.
Published: March 2009

Large area, highly uniform vertically aligned carbon nanotips (VACNTP) and other nanostructures have been grown on silicon (100) substrates with Ni catalyst in the low-temperature, lowfrequency, high-density inductively coupled plasmas (ICP) of methane-hydrogen-argon gas mixtures. The control strategies for the morphology, crystalline structure and chemical states of the resulting nanostructures by varying the growth conditions are proposed. XRD and Raman analyses confirm that the nanotips are well graphitized, which is favorable for the field emission applications.
Multi-Walled Carbon Nanotubes without and with Metal Filling
Authors: Schaper Andreas K. , Hou Hao Qing , Treutmann Werner , Phillipp Fritz
Published: March 2009

Electron microscope studies are reported of MWCNTs without and with metallic
encapsulations prepared by pyrolysis of organo-metallic precursors such as iron(II)phthalocyanine and ferrocene/anthracene mixtures. For straight and well-ordered MWCNTs, we obtained clear evidence of a scroll type structure with uniform chirality. Conical growth implicated the opening of the tube walls by termination of the graphene layers at the wall surfaces. Evidence is provided of
the participation of iron carbide as an intermediate phase during graphite formation. Coercivities of the nanowire material up to 2550 Oe at 5 K, and constant saturation magnetization were measured.
Simultaneous Measurement of Epinephrine and Ascorbic Acid at the Carbon Nanotube Electrode
Authors: Hu C.G. , Wang W.L. , Liao K.J. , Wang Y.T.
Published: March 2009

Electrochemical behaviors of epinephrine and ascorbic acid have been studied at the carbon nanotube electrode using cyclic voltammetry. Electrocatalysis has been found for epinephrine redox reactions at the carbon nanotube electrode in the comparison with the glassy carbon electrode. A well-defined oxidative peak for ascorbic acid was observed at the carbon nanotube electrode with the peak potential negative shift versus the glassy carbon electrode. Low level of epinephrine can be determined at the carbon nanotube electrode selectively with high sensitivity in the presence of a large excess of ascorbic acid in the acidic media and in the physiological pH buffer solution.
Study on Piezoresistive of Doped Carbon Nanotube Films
Authors: Wang W.L. , Liao K.J. , Cai C. , Hu C.G. , Ma Y. , Lu J.W.
Published: March 2009

The piezoresistive effect in iodine-doped carbon nanotube films was investigated by a three-point bending test. Carbon nanotubes were synthesized by hot filament chemical vapor deposition. The experimental results showed that the gauge factor for I-doped and undoped carbon nanotube films under 500 microstrain was about 350 and 65 respectively at room temperature, exceeding that of polycrystalline silicon (30) at 35°C. The origin of the piezoresistivity in the films may be ascribed to a strain-induced change in the band gap for the doped tubes and the intertube contact resistance and defects for the undoped tubes.
Ag Dispersed Conducting Polyaniline Nanocomposite as a Selective Sensor for Ammonia
Authors: Athawale Anjali A. , Katre Prachi P.
Published: March 2009

Silver nanoparticles were synthesized by irradiating silver nitrate solution (10-4
M) (methanol:water as a solvent) with different concentrations of aniline as a stabilizer in a 60Co g-ray source at a dose rate of 1.1 kGy. The particles exhibiting maximum stability up to a period of 7 days were obtained at the concentration of 0.1M aniline. The average particle size of the nanoparticles as estimated from XRD and TEM was found to be ~23 nm. Silver-Polyaniline (Ag-Pani) nanocomposite was prepared by oxidative polymerization of aniline. The applicability of synthesized nanocomposite as a sensor was tested by exposing the same to different chemical vapors viz. alcohols, amines, ammonia, chloroform etc. The results revealed its selectivity towards ammonia vapors and a long term stability of response is observed up to a period of two months. The above results are well supported by FT-IR spectroscopy.
Design of Novel Nanocomposites through Interfacial Engineering
Authors: Sindhu S. , Jegadesan S. , Renu R. , Valiyaveettil S.
Published: March 2009

Two classes of nanocomposites involving polymers and magnetic particles or silica were synthesized and characterized. Effect of polymer on the morphology of the composites and the matrix filler interactions were studied in detail. Different analytical tools were used to characterize these composites and show a core-shell structure for the novel nanocomposites reported in this paper. TEM studies on these composites gave particle size distribution in nanometer range. The morphology
and size of the particle changed significantly with the polymer used.
Electrical Conductivity of Quantum Size 2d Nanocomplex
Authors: Gupta N. , Mallik H. , Sarkar A.
Published: March 2009

A nanocomplex of Chromium oxide nanoparticles with biopolymer matrix of gum
Arabica is synthesized by natural self-assembly in chemical sol-gel route. Gum Arabica is chosen as base matrix due to its inherent biodegradable property. Experimental specimen of the said complex is prepared to satisfy near quantum size effect criterion. Due to near quantum size effect and spatial localization of nanoclusters, the developed specimen becomes an ideal 2D quantum well system.
The longitudinal electrical conduction of the developed system is studied experimentally. Some of its structural aspects are also investigated to make the study conclusive. The dispersed cluster size is estimated by Transmission Electron Microscope (TEM) and X-ray diffraction (XRD). The results of I-V characteristics at temperatures 253 K show the distinctive features of localized energy levels. The spacing between energy levels near ground state to be comparable to the thermal energy at temperature 253 K for a cluster dimension below 10 nm. In this present study the developed specimens with the mentioned nanoclusters estimated from TEM and XRD as below 10 nm. The overall results are found to be encouraging.
Study on Thermooxidative Degradation of Poly(Vinyl Alcohol)/Silica Nanocomposite Prepared with SAM Technique
Authors: Peng Zheng , Kong Ling Xue , Li Si Dong
Published: March 2009

The thermooxidative degradation of poly (vinyl alcohol)/silica (PVA/SiO2)
nanocomposite prepared with self-assembly monolayer (SAM) technique is investigated by using a thermogravimetry (TG) and Fourier transform infrared spectroscopy coupled thermogravimetry (FTIR/TG). The results show that although the thermooxidative degradation process of prepared nanocomposite is similar to that of the pure PVA, its thermooxidative stability has been greatly improved.
Linking Additive Structures to Nanoparticle Properties
Authors: Richmond William R. , Parkinson Gordon M. , Jones Franca , Ogden Mark I. , Oliveira Allan , Reyhani Manijeh , Rohl Andrew L.
Published: March 2009

The effects of a series of polyphosphonate and poly-carboxylate additives have been investigated in the crystallization of various inorganic salts. Systematic variation of the additive structure has been used to provide insight into the dominant factors in additive-crystal interactions. The results obtained for barium sulfate and hematite (α-Fe2O3) show that the morphological effects do not necessarily follow the trend one might expect on the basis of the structural features of the additives. Molecular modeling, coupled with in-situ AFM imaging is being used to develop an
approach that will allow more informed systematic design of crystal growth modifiers.
Preparation and Characterization of ZnSe/SiO2 Nanocomposite
Authors: Kong Fantao , Yao Xi , Wang Min Qiang , Jiang Haiqing , Wang Yun Peng
Published: March 2009

Semiconductor ZnSe nanocrystals (NCs)-doped SiO2 glasses (designated as ZnSe/SiO2 nanocomposites) were prepared successfully by using sol-gel method and in-situ growth technique. The nanocomposite was characterized by X-ray diffraction (XRD) patterns, UV-Vis absorption spectra and X-ray Photoelectron Spectroscopy (XPS). The XRD results show that ZnSe NCs is zinc blende structure and the mean size is smaller than 5nm in diameter. UV-Vis absorption spectra reveals that the size of the NCs is influenced by synthesis conditions such as doping concentration and thermal treatment, and XPS together with XRD can prove that silica matrix plays an important role in enhancing the NCs’ stability.
Preparation of Porous Alumina by Anodization
Authors: Xu C.X. , Zhang X.S. , Sun X.W.
Published: March 2009

The characteristics of porous alumina produced by anodization in both oxalic acid and sulfuric acid solution have been studied. The diameter of the pores for oxalic acid as electrolyte is about 60 nm and for sulfuric acid as electrolyte is about 30 nm. The morphologies of the pores have been improved by two-step anodization process. It has been observed that the temperature and operation voltage are two of the most important factors in the fabrication process of porous alumina films.