bluuebunny/crossref_metadata_2025 huggingface dataset:
Ageing Studies of Plasma Deposited Organic Films by Surface Chemical Analysis (ESCA, ToF-SIMS, XAS)
Authors: Unger Wolfgang E.S. , Oran Umut , Swaraj Sufal , Lippitz Andreas
Published: March 2009

The formation of plasma-polymerized materials made from organic molecules is a
technologically attractive way to obtain films with unique properties for life science
applications. Surface properties like bio-compatibility, wettability, etc., can be adjusted by
tailoring the chemical functionalization. It is well known that after deposition these films
undergo post-plasma reactions, especially when they are exposed to ambient atmosphere.
Most often, in applications these films are not used immediately after their deposition – they
are usually stored for a certain time. Therefore there is a need for a development of analytical
procedures enabling studies of ageing phenomena of plasma chemically deposited films. With
the help of these studies a better understanding of basic post-plasma reaction phenomena as
well as relevant empiric information for practical applications can be obtained. However, a
detailed chemical characterization of plasma chemically deposited films is a great challenge
for the analysts because of the co-existence of a number of different chemical species.
We investigated r.f. plasma-polymerized organic films by using photoelectron spectroscopy
for chemical analysis (ESCA), spectroscopy of the near edge X-ray absorption fine structures
(NEXAFS) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). Ethylene,
styrene, allyl alcohol and allyl amine were used as monomers. A dedicated plasma
preparation chamber was designed and added to the main analysis chamber of the respective
spectrometer. This approach offers the possibility to study plasma-polymerized films in situ
and, subsequently, the influence of post-plasma reactions. The important effect of air
exposure of the film, in terms of plasma technology denominated as “ageing”, can be studied
subsequentially step by step by this unique approach.
Trivalent and Hexavalent Chromium Issues in Medical Implants
Authors: Eiselstein Lawrence E. , Proctor D.M. , Flowers T.C.
Published: March 2009

Metal alloys containing chromium (Cr), primarily stainless steels and CoCr alloys, are
used in a wide variety of implantable medical devices. These alloys are exposed to chloride
containing environments with varying oxidizing potential and complexing agents. These corrosion
assisted environmental effects may result in metal ions going into solution. The toxicity of Cr is
dependent on valence state. Hexavalent Cr ions are recognized to be more toxic than trivalent Cr.
This paper discusses the state of knowledge regarding Cr release, the chemical and mechanical
factors that most significantly affect Cr release, and the potential toxicity of Cr as it applies to longterm
implantable medical devices.
In Vivo and In Vitro Evaluation of Coated HAp Films with Different Surface Morphology
Authors: Kuroda Kotaro , Ichino Ryoichi , Okido Masazumi
Published: March 2009

Hydroxyapatite (HAp) coatings were formed on cp titanium plates and rods by the
thermal substrate method in an aqueous solution that included 0.3 mM Ca(H2PO4)2 and 0.7 mM
CaCl2. The coating experiments were conducted at 40-140 oC and pH = 8 for 15 or 30 min. The
properties for the coated samples were studied using XRD, EDX, FT-IR, and SEM. All the specimens
were covered with HAp, which had different surface morphologies such as net-like, plate-like and
needle-like. After cleaning and sterilization, all the coated specimens were subjected to in vivo and
vitro testing. In the in vitro testing, the mouse osteoblast-like cells (MC3T3-E1) were cultured on the
coated and non-coated specimens for up to 30 days. Moreover, the specimens (φ2 x 5 mm) were
implanted in rats femoral for up to 8 weeks, the osseoinductivity on them were evaluated. In in vitro
evaluations, there were not significant differences between the different surface morphologies. In in
vivo evaluations, however, two weeks postimplantation, new bone formed on both the HAp coated
and non-coated titanium rods in the cancellous and cortical bone. The bone-implant contact ratio,
which was used for the evaluation of new bone formation, was significantly dependent on the surface
morphology of the HAp, and the results demonstrated that the needle-like coating appears to promote
rapid bone formation.
Corrosive-Erosive Wear Studies of Al6061/Albite Composites
Authors: Sharma S.C. , Krishna M. , Murthy H.N. Narasimha
Published: March 2009

This investigation analyses the influence of dispersed alumina particles on
the wear behaviour of the Al/albite composites in a corrosive environment. The
composites were prepared by modified pressure die-casting technique. The corrosiveerosive
wear experiments were carried out on a proprietary corrosion-erosion wear
tester to study the wear characteristics of the composites. The slurry was made up of
water and alumina(size: 90-150μm, proportion: 0 to 30 wt %) , while H2SO4 (0.01N,
0.1 N and 1 N) was added to create the corrosive conditions. Experiments were
arranged to test the relationships among the corrosive-erosive wear rate, concentrations
of H2SO4 and alumina in the slurry, weight percent of albite in the composite, erosion
speed and distance. Wear rate varies marginally at low speeds but sharply increases at
higher speeds. The corrosive wear rate logarithmically increased with the increasing
concentration of the corrosive medium. The effect of abrasive particles and corrosion
medium on the wear behaviour of the composite is explained experimentally.
Development of New Low Cost Discontinuously Reinforced Titanium Composites for Commercial Applications
Authors: García de Cortázar M. , Goñi Javier , Coleto J. , Agote I. , Egizabal P. , Lepetitcorps Y.
Published: March 2009

A new cost effective process to produce discontinuously reinforced (TiB) TMCs has been
developed. The article presents general features of the composites, microstructural characteristics and
mechanical properties. The production and characterization of two potential commercial applications
are also discussed.
Importance of Composite Design for the Microstructure of Bundle Drawned Multifilamentary Nb3Sn Wires
Authors: Taillard Roland , Guyot S. , Verwaerde Christophe
Published: March 2009

Composites made of niobium filaments within an oversaturated α-CuSn bronze matrix
were processed by restack bundle drawing. The differences in mechanical behaviour of the various
components entail an heterogeneity of deformation. Such a feature is mostly unfavourable not only
for the phase transformations that govern the microstructure and the electromagnetic properties but
also for the composite mechanical integrity. The obtained results finally demonstrate the chief
importance of the selection of both the design of the composite and the processing steps.
Laser Zone-Remelted Alumina-Based Eutectic In Situ Composite
Authors: Zhang Jun , Su Hai Jun , Liu Lin , Fu Heng Zhi
Published: March 2009

Due to excellent oxidation and corrosion resistance at elevated temperature, oxide ceramic
could be the preference served at high temperature oxidizing atmosphere over a long period of time.
In recent years, alumina-based eutectic in situ composite prepared by various solidification
techniques, which has superior properties even close to the melting point about 2100K, has been paid
much attention. In this paper, Al2O3/YAG/ZrO2 ternary eutectic and hypoeutectic ceramics are
prepared from melt by laser zone-remelting technique, the rapid solidification characteristic and the
mechanical property of the composites are investigated. The results show that: (1) Compared to
sintered composite with the same composition, laser zone-remelted Al2O3/YAG/ZrO2 eutectic in situ
composite has different microstructure showing fine interpenetrated network with Al2O3, YAG and
ZrO2 phases continuously intergrown, while none of pores, grain boundaries and amorphous phases
is found. (2) The scanning rate and the power density of the laser beam has strong effect on the
microstructure morphology. When the power density is determined, the eutectic spacing is reduced
with the scanning rate increased. The characteristic eutectic spacings and phase sizes of YAG and
Al2O3 are about 2~3μm, and the characteristic dimension of ZrO2 is less than 1μm. (3) The hardness
and the room-temperature fracture toughness of Al2O3/YAG/ZrO2 eutectic are respectively
Hv=16.7±2.0 GPa and KIC=8.0±2.0 MPa.m1/2, and those of hypoeutectic are respectively
Hv=15.8±2.0 GPa and KIC=3.9±1.0 MPa.m1/2.
Crystal Structure of the β'-Phase in Al-Mg-Si-Ag Alloy
Authors: Matsuda Kenji , Nakamura Junya , Nakamura Yoshio , Sato Tatsuo , Ikeno Susumu
Published: March 2009

The crystal structure of metastable phase in Ag added Al-Mg-Si alloy was investigated
by comparing the β’-phases in Al-Mg-Si alloy without Ag, using images of high resolution
transmission electron microscope (HRTEM), selected area electron diffraction patterns (SADPs)
and an energy dispersive X-ray spectroscopy (EDS). SADPs and HRTEM images obtained from
metastable phase in the Ag added Al-Mg-Si alloy showed similar to those of β’-phase in Al-Mg-Si
alloy without Ag and had different lattice spacings because of the effect of Ag. According to our
careful analysis on obtained HRTEM images and SADPs, it includes more complicated crystal
lattice of distorted hexagons.
Structure and Properties of PM Composite Materials Based on EN AW-AlCu4Mg1(A) Aluminium Alloy Reinforced with the Ti(C,N) Particles
Authors: Dobrzański Leszek Adam , Włodarczyk-Fligier Anna , Adamiak Marcin
Published: March 2009

Investigations of composite materials based on EN AW-Al Cu4Mg1(A) aluminum alloy
reinforced with the Ti(C,N) particles with various weight ratios of 5, 10 and 15% are presented. The
metallographic examinations of composite materials show banding of the reinforcing particles in
aluminum matrix after extrusion process. Structure oriented in parallel with extrusion direction is
observed in composites materials. Portion of reinforcement particles Ti(C,N) has influence on the
mechanical properties of composite materials. The increase of hardness, abrasive wear and decrease
of compression strength, tensile strength is observed with the portion growth of reinforcement
particles.
An Analysis on the Tensile Strength of Hybridized Reinforcement Filament Yarns by Commingling Process
Authors: Herath Chathura Nalendra , Hwang Beong Bok , Ham B.S. , Seo Jung Min , Kang Bok Choon
Published: March 2009

Carbon, aramid and glass fibers are inherently superior to conventional textile fibers in
terms of mechanical properties as well as other chemical characteristics. Because of inherent
advantages and disadvantages associated with each material, it is generally better to hybridize them
to fully benefit of their high performance in many practical applications. In this paper, the
possibility of hybridizing Carbon/Aramid-, Carbon/Glass- and Aramid/Glass- matrices has been
investigated through the commingling process. In the experiment, several process parameters were
selected and they include pressure, yarn oversupply-rate and different nozzle types. As a result of
experiments, it was concluded that the hybridized materials has shown better performance than
individual reinforced filament yarns in terms of mechanical properties. For small tensile forces, the
Carbon/Glass/matrix combination turned out to be good enough for general purpose applications.
However, for high tensile applications, Carbon/Aramid or Aramid/Glass with matrix combinations
was better than the other material combinations. The hybridization process was also investigated
under an air pressure of 5 bar, a yarn oversupply-rate of 1.5% for reinforced filaments, and 3.5% to
6% for matrix materials, respectively. It was also shown from the experimental results that
Carbon/Glass/matrix combination may be desirable for small tensile force applications and
Carbon/Aramid/matrix and Glass/Aramid/matrix combinations most suitable for heavy tensile
force applications, respectively. As a matrix material, polypropylene and polyester have shown
better performance than polyether-ether-keeton in terms of tensile property.
An Assessment of Mechanical Properties of Geo-Grid Reinforced Material and its Applicability
Authors: Hwang Beong Bok , Lee Y.H. , Min K.H. , Seo Jung Min , Jeon Han Yong
Published: March 2009

Geo-composites are generally made by hybridizing of some components among
geo-textile, geo-grid, geo-membrane, geo-net, and other materials. Due to practical applicability of
geotechnical structures, the demand of geo-composites, especially for drainage application, has
gradually increased. In the present study, the geo-composites bonded with geo-grid in chemical
process were investigated experimentally in terms of strain evaluation and creep response values.
Geo-grid plays an important role as a reinforcing material. Three kinds of geo-grid were prepared as
strong yarn polyester and they were woven type, non-woven type, and wrap knitted type. The sample
geo-grids were then coated with PVC. The rib tensile strength tests were conducted to evaluate
geo-grid products in terms of tensile strength with regard to single rib. The test was performed
according to GRI-GGI. The test results revealed that the tensile strains at the maximum tensile
strength showed very good tensile deformation characteristics in the range of 10.0-13.0% in terms of
mono-rib performance. Any significant trends have not found between warp knitted and woven type
geo-grid in terms of the tensile strength ratios. Further experimental analysis has been conducted to
investigate the wide-width strip tensile strength, contact point strength and creep features of the
geo-grid samples used in this study. It was concluded again from the experiments that the tensile and
creep strains of the geo-grid showed so stable values that the geo-grid prepared in this study could
protect geo-textile partially in practical structure.
Microscopic Evaluation of Commingling-Hybrid Yarns
Authors: Kang Bok Choon , Min K.H. , Lee Y.H. , Hwang Beong Bok , Herath Chathura Nalendra
Published: March 2009

Fibers made of elements such as carbon, aramid and glass have higher mechanical
properties than other conventional textile fibers and they enable the production of light weight
composites as end products. Furthermore, commingling hybrid yarns generally have a characteristic
feature so that their components are distributed homogeneously enough over the yarn cross section. A
normal air texturerising machine was modified to produce commingling hybrid yarns for test samples.
Different process parameters were applied to produce the hybridized yarn samples. However, these
process parameters turned out to have little effect on the filament distribution over the hybrid yarn
cross section in terms of homogeneity. The analysis in this paper is focused on the pattern of mixing
of filaments over a cross section of hybrid yarns according to different combinations of reinforcement
and matrix filament yarns through microscopic view. The volume content of filament in hybrid yarn
cross section was maintained at 50% for both reinforced and matrix, and the hybrid yarns count at 600
tex throughout experiments. It was concluded from the experiments that the diameters of
reinforcement and matrix filaments have strong effects on the pattern of mixing of filaments over a
cross section of hybrid yarns such that the hybrid yarns with more or less equal diameters of
reinforcement and matrix filaments showed considerably even distributions over the hybrid yarn
cross section.
Effects of Homogenization Treatment on Thermoelectric Properties of Ba8Al16Si30
Authors: Lee Joo Ho , Lee Jung Il , Kim Young Ho , Kim Il Ho , Jang Kyung Wook , Ur Soon Chul , Choe Han Cheol , Yang Gon Seung
Published: March 2009

The Arc melting technique was employed to synthesize the type I clathrate of Ba8Al16Si30 compound. Phase transformations during synthesis and homogenization treatment were investigated using X-ray diffraction (XRD) and thermal analysis (TG/DSC). Thermoelectric properties as functions of temperature and homogenization treatment time were evaluated in this study. Maximum ZT was 0.14 at 590K for homogenized at 1173 K for 168hrs specimen and it is strongly expected to show higher value above 600K.
Preparation and Characterization of n-HA/Chitosan Scaffold Prepared by a New Method of Emulsion-Foaming/Freeze-Drying Process
Authors: Zhang Li , Li Yu Bao , Shi Pu Jiang , Zuo Yi , Wu Lan
Published: March 2009

A novel nano-hydroxyapatite/chitosan (n-HA/CS) composite scaffold with high porosity
was developed by a new method of emulsion-foaming/freeze-drying process and was characterized
by means of infrared spectroscopy (IR), scanning electronic microscopy (SEM) and universal
material testing machine. In addition, the porosity and density of the scaffold were also calculated.
IR result shows that the characteristic absorption peaks belonging to both CS and HA are present in
their composite, and the slight band-shifts and peak-decrease suggest that some interactions have
taken place between the two phases of CS and n-HA in the composite. SEM photo displays that,
with the dosage increase of Tween-80, the prepared scaffold shows highly porous and
interconnected structure, in which macropores and micropores coexist. The calculated data
demonstrate that the porosity of the scaffold is proportional to the content of the emulsifier, while
the compressive strength is inversely. When 15wt% emulsifier used, the porosity of the scaffold can
be up to 90% and the density is 0.453g/cm3, while the corresponding compressive strength is about
2.4MPa. The newly developed n-HA/CS composite scaffolds may serve as a good 3-D substrate for
cell attachment and migration in bone tissue engineering.
Thick-Film CO2 Sensors Based on NASICON Synthesized by a Sol-Gel Process
Authors: Kim Han Ji , Choi Jung Woon , Kim Shin Do , Yoo Kwang Soo
Published: March 2009

Thick-film CO2 sensors were fabricated using a sodium super ionic conductor
(NASICON: Na1+xZr2SixP3-xO12) with a series of Li2CO3-BaCO3 auxiliary phases. The powder of a
precursor of NASICON with high purity was synthesized by a sol-gel process. Using the
NASICON paste, an electrolyte was prepared on the alumina substrate through screen printing and
then sintered at 1000°C for 5 hours. The resulted NASICON thick film was characterized by XRD
and FESEM. Within a wide range of CO2 volume ratio concentration from 1,000 to 10,000 ppm,
the output of the sensor showed a good electromotive force (EMF) response that was very close to
the theoretical value. The sensor attached with a binary carbonate auxiliary phase Li2CO3-BaCO3
(1:2) showed fairly good CO2 sensing properties at 470°C.
Characters of Coarse Grains Subdivisions in Rolled Polycrystalline Al
Authors: Hu Qi Ping , Zhang Yong , Deng Yun Lai
Published: March 2009

Deformation microstructures and micro-orientations of columnar grains with different
orientations in a polycrystalline high purity Al cold-rolled up to 65% (thickness reduction) were
investigated using electron backscatter diffraction (EBSD) technique. It was found that rotations were
Inhomogeneous within the individual grains, the rotation angles of the parts close to the initial
boundaries (BPs) were smaller than those remote from the boundaries (IPs), e.g. the deviation angles
between the BPs and the IPs were 5-6° in the grains with <001>//RD orientation, leading to the
rotation along the α-fiber, while the deviation angles were 5-12° in the grains with <121>//ND
orientation rotating toward the β-fiber. These results demonstrated that the microstructures and local
rotations of various parts within the rolled individual columnar grains were influenced by their initial
orientations and boundaries.
Investigation of Flow Stress Behavior and Microstructural Evolution of 7050 Al Alloy
Authors: Yi You Ping , Chen Hua , Lin Yong Cheng
Published: March 2009

The plastic deformation behaviors of 7050 Al alloy were investigated by compression tests
at temperatures ranging of 250°C450°C under constant strain rates of 0.01s−1, 1s−1 and 10s−1. The
results showed that all the flow curves consisted of three stages, i.e. strain-hardening, strain-softening
and steady state-strain. Initially, the stress rises steeply at microstrain deformation, and then increases
at a decreased rate, followed by a strain-softening until a steady state stress. The stress level decreases
with increasing deformation temperature and decreasing strain rate, which can be represented by a
Zener-Hollomon parameter in an exponent-type equation,
1 19 7.202 σ p 80.71 sinh (1.64 10 Z)
= ⋅ −  × − ⋅ −  .
Elongated grains with serrations developed in the grain boundaries were observed; the dynamic
recrystallization (DRX) occurs with increasing temperature and dislocation density, and the shape of
grain at steady state is nearly equiaxial. It can be concluded that the DRX phenomenon is sensitive to
the temperature and the dynamic flow softening is mainly as the result of dynamic recovery and DRX.
Influence of Zr on the Microstructure and Mechanical Properties of an Al-Zn-Mg-Cu Alloy
Authors: Yang Shou Jie , Xie You Hua , Dai Sheng Long , Yan Ming Gao
Published: March 2009

Recently, a new super-high-strength Al-Zn-Mg-Cu alloy with Zr bearing was developed in
BIAM. In this paper, the effect of microalloying element Zr on the microstructure and mechanical
properties of the alloy was investigated. It was found that the influence of Zr on the microstructure
and age-hardening behaviors was remarkable. The strength of the alloy increases with increasing the
content of zirconium, and the peak value of the elongation appeared when the content of Zr was
0.06%(mass fraction) and then decreases. The fracture behavior was also studied. The result shows
that the fracture mechanism of the alloy was converted from intergranular brittle to transgranular
ductile model with increasing the content of zirconium. Finally, the optimum contents of Zr in the
alloy were proposed as 0.10%~0.14%.
Tensile Properties of Large Extrusion and Forgings of RS P/M Al-9Fe-1.9Mo-1.7Si Aluminum Alloy
Authors: Li P.Y. , Li W. , He X.L. , Dai Sheng Long , Wang S.Y. , Li H.Q. , Yang H.T.
Published: March 2009

Large extrusion and forgings of Al-9Fe-1.9Mo-1.7Si (wt.%, FMS0918) aluminum alloy for
elevated temperature applications were produced by rapidly solidified powder metallurgy process.
Powders of FMS0918 alloy were produced by inert gas atomization, and then screened, canned,
degassed, extruded and forged. The extrusion exhibited good strengths and elongation in longitudinal
orientation, but low elongation in long- and short-transverse orientations. After forged, the tensile
strengths of the forgings showed little change, but the long- and short-transverse elongation was
improved.
Thermal Stability of Nanocrystallized Surface Layer in Al-Zn-Mg Alloy by Surface Mechanical Attrition Treatment
Authors: Ma Jin Fang , Hu Lan Qing , Liu Xu Guang , Xu Bing She
Published: March 2009

After surface mechanical attrition treatment (SMAT) for Al-Zn-Mg alloy, a gradient
structure with average grain size increased from 20nm in surface layer to about 100nm at a depth of
20μm was formed. The thermal stability of surface nanostructured layer in Al-Zn-Mg alloy samples
was investigated by vacuum annealing at 100°C, 150°C, 200°C and 250°C for 1h, respectively. The
microstructural evolution as well as the microhardness along the depth from top surface layer to
matrix of SMATed samples was analyzed. Experimental results showed that the grain size of surface
nanocrystallites remains in submicro-scale, ranging from 300nm to 400nm, when annealed at a
temperature of 250°C, and the microhardness of surface nanostructured layer was still high compared
with that of matrix, indicating satisfying thermal stability of nanocrystallized layer. This might be
attributed to the presence of substantive trident grain boundaries and pinning effect of dispersive
precipitated phases in nanocrystalline materials, which hindered the grain boundary migration that
leading to grain growth.
Surface Morphology and Discharge Channel Temperature Estimation of PEO Ceramic Coatings on Aluminum
Authors: Shen De Jiu , Gu Wei Chao , Wang Yu Lin , Xing Guang Zhong , Nash Philip
Published: March 2009

The surface roughness and morphology of the ceramic coatings fabricated on industrially
pure aluminum by the plasma electrolytic oxidation (PEO) technique with a hetero-polar pulsed
current ceramic synthesizing system were investigated. A model for the process was established.
Based on this a formula was deduced to estimate the temperature rise rate at the corresponding
locations before the plasma discharge channels have formed during the PEO process, and the
channels’ temperature when the plasma discharges occur. Results show that the PEO ceramic
coatings grow by an alternating coating melting and solidifying way; The coating roughness becomes
greater and the plasma discharge channel population in the ceramic coatings decreases while the pores
enlarge with PEO treatment time and current. With the deduced formula, the PEO alumina coating on
industrially pure aluminum was taken as an example for validation of the model.
Influence of Ru and Cr on the Heat-Treated Microstructure of Ni-Based Superalloys
Authors: Wang W.B. , Feng Qiang , Carroll L.J. , Wang Y.L. , Chen Guo Liang , Pollock T.M.
Published: March 2009

The effects of ruthenium and chromium contents have been investigated on phase transformation temperatures and the morphology of γ’ precipitates as well as microstructural stability in high refractory Ni-base superalloys. The solidus and liquidus temperatures were determined by differential scanning calorimetry (DSC), suggesting that the addition of Cr resulted in a decrease in solidus/liquidus temperatures while the Ru addition (3.5 at.%) had the neutral effect. The morphology of γ’ precipitates in the heat-treated microstructure was changed under the influence of the Cr and Ru additions, suggesting that Ru and Cr contents affected the γ−γ’ lattice misfit through changes in the associated partitioning to the constituent phases. The microstructural instability has been investigated at 1000 oC. High levels of Cr addition (8 at.%) strongly promoted the formation of TCP phases, while Ru improved the microstructural stability to some extent.
Effect of Alloying Elements on Microstructure and Mechanical Properties of High Temperature Die Material DM02 Alloy
Authors: Song Jin Xia , Li Qing , Xiao Cheng Bo , Han Ya Fang
Published: March 2009

The effect of Ta, Nb, Hf and Zr on the microstructure and high temperature tensile
properties of DM02 alloy, which is a novel developed Ni base superalloy for high temperature die
material, had been studied in this paper. The results showed that the four alloying elements affect the
composition and morphology of carbides obviously, and have almost no effect on the morphology and
size of γ´ phase in DM02 alloy. 0.5-1wt% Hf make the morphology of MC carbide change from
bone-like to blocky and inhibit the formation of primary M6C carbide, thus improve the ductility of
DM02 alloy, while 0.1wt% Zr has no similar effect. The strengthening effect of 3wt% Ta is better
than that of 1.5wt% Nb. DM02 alloy with 3wt% Ta and 0.5wt% Hf has high strength and good
ductility at 1050°C.
Optimization of Nd:YAG-Laser Welding Process for Inconel 718 Alloy
Authors: Xiao Min , Poon Cheung , Wanjara Priti , Jahazi Mohammad , Fawaz Zouheir , Krimbalis P.
Published: March 2009

Ni-based superalloys are extensively used in the manufacture of aircraft engine
components because of their excellent heat-resistant and corrosion-resistant properties. The principal
joining processes for Ni-based superalloys are TIG welding, MIG welding, submerged arc welding,
electron beam welding, and CO2 laser welding. In this investigation, a robotic 4-kW continuous-wave
Nd:YAG laser system was used to identify the optimal laser welding process for 2.0 mm thick Inconel
(IN) 718 sheets. The effect of various processing parameters, which included power input, welding
speed, weld geometry and filler wire, was studied using the Taguchi design of experiment (DOE)
methodology. The DOE methodology enabled the evaluation of the relationship between the process
parameters and the quality of the welded joints, from which the optimal Nd:YAG laser welding
process was developed for IN718 alloy. Joint quality was examined by tensile and nondestructive
testing methods. Using the optimal process established in this research, mechanically-sound welds
with narrow fusion and heat-affected zones were produced. The outcome of this research
demonstrates the feasibility of the application of Nd:YAG laser in the joining of IN718 sheets for the
manufacture of aircraft engine components.
Research on Sheet Metal of a New Ni-Based Superalloy Prepared by EB-PVD
Authors: Chen Gui Qing , Li X.H. , Meng Song He , Han Jie Cai , Li Qing Fen
Published: March 2009

The sheet metal of a new Ni-based superalloy has been prepared by Electron Beam Physical
Vapor Deposition (EB-PVD) technology. The phases, the microstructures and mechanical properties
of this alloy before and after heat treatment have been analyzed by X-ray diffractometer, transmission
electron microscope, optical microscope, scanning electrical microscope and tensile equipment.
Results showed that the size of γ' particles increases gradually and the morphologies of γ' particles
changed from spherical shape into cubical shape when temperature increased from low to high.
Compared with as-deposited alloy, mechanical properties of heat-treated alloy were improved
obviously. It is feasible that superalloy of better properties can be prepared by EB-PVD technology.
Quantification of High Temperature Strength of Nickel-Based Superalloys
Authors: Guo Zhan Li , Saunders N. , Miodownik Alfred Peter , Schille J.P.
Published: March 2009

The strength of nickel-based superalloys usually consists of solid solution strengthening from the gamma matrix and precipitation hardening due to the gamma' and/or gamma" precipitates. In the present work, a model was developed to calculate the high temperature strength of nickel-based superalloys, where the temperature dependence of each strengthening contribution was accounted for separately. The high temperature strength of these alloys is not only a function of microstructural changes in the material, but the result of a competition between two deformation modes, i.e. the normal low to mid temperature tensile deformation and deformation via a creep mode. Extensive validation had been carried out during the model development. Good agreement between calculated and experimental results has been achieved for a wide range of nickel-based superalloys, including solid solution alloys and precipitation-hardened alloys with different type/amount of precipitates. This model has been applied to two newly developed superalloys and is proved to be able to make predictions to within useful accuracy.
Optimisation of Spray Forming Ni Superalloys via Process Modelling and On-Line Monitoring
Authors: Mi Jia Wei , Grant Patrick S.
Published: March 2009

The optimisation of spray forming IN718 alloy rings for aeroengine applications was
investigated using both modelling and experimental approaches. A multiphysics numerical model has
been developed and implemented to assist in the optimisation of the spray forming process.
IN718 alloy ring preforms were spray formed at University of Oxford (UK) and The University of
Bremen (Germany). A variety of on-line monitoring facilities were integrated onto spray forming
units to (1) investigate the dynamics of alloy melt atomisation and droplet deposition at a sprayed
surface; and (2) acquire ring preform thermal history and various thermal boundary conditions for the
numerical model. Modelling and experiments were performed iteratively to investigate the effects of
key spray forming parameters including gas metal flow ratio, atomiser scan, substrate heating
schemes on the resulting ring preform shape, internal heat flow and solidification. It was found that
preform top surface temperature and alloy liquid fraction inside the preform during spray forming
were critical factors in governing the formation of macro/microporosity and the grain size of
as-sprayed preforms. In the optimised conditions, IN718 alloy ring preforms were characterised by a
microporosity of less than 1.5% and randomly oriented equaxied grains of 20-50 μm.
Mechanical Properties and High Temperature Deformation of Beta Titanium Alloys
Authors: Zhou Qing , Itoh Goroh , Niinomi Mitsuo
Published: March 2009

Because of its excellent environmental resistance and cold-working capacity, beta titanium
alloy Ti-15-3 has attracted more and more attention in aerospace manufacture industry. Another beta
titanium alloy, Ti-29-13, has been recently developed for biomedical implant materials. The
mechanical properties of three alloys including two β and one α+β are presented, particularly the
characteristic of β alloy differing from that of α+β alloy. The high temperature deformation behaviors
of two alloys are also presented. Excellent formability of Ti-15-3 highlights the metal sheet
application in commercial and military airplane. Band structure in Ti-29-13 has been found.
Thermalmechanical processing is carried out to reduce the band structure and improve the elongation.
Predeformation Effects on Shear Response and Microstructure in Pure Titanium-TA2
Authors: Li Shu Hua , Wang Fu Chi , Tan Cheng Wen , Chen Zhi Yong , Sun Zhi
Published: March 2009

Adiabatic shear properties of pure titanium-TA2 have been investigated using specially
designed specimen in a Hopkinson pressure bar at high strain rate of 103s- 1. Microstructural
characteristics was investigated using scanning electrion microscopy as well as transmission and high
resolution transmission electrion microscopy .The results showed that the shear stress and adiabatic
sensitivity for rolled 45% TA2 are higher than forged TA2. Comparing the adiabatic shear bands
(ASB) both in the forged and rolled TA2, no evidence in morphology alteration was found except to
shear band widths. The transmission electron micrograph of the ASB in forged and rolled TA2
showed the grain size reduction from ~20μm to 200nm. No deformation twins have been observed in
ASB. The selected area electron diffraction patterns of the ASB showed reflections of multiple grains,
forming discontinuous rings which can be indexed as h.c.p. structure of α-Ti. This indicates that the
ASB consists of fine grains of α-Ti and the α-Ti→ β-Ti transformation did not occur.
In Situ Composites: Effect of Intermolecular Hydrogen Bonds on Polyamide 66/TLCP Blends
Authors: Zhang Zhuo , Guo Hong Jun , He Wei , Zhang Wen Xion
Published: March 2009

The thermotropic liquid crystalline copolyamide (TLCPa) was synthesized and the in situ
composites for TLCPa/Polyamides 66 (PA66) were prepared by melting extrusion. As revealed by
differential scanning calorimeter (DSC), depression of the melting point and the crystallinity of PA66
indicated that the miscibility was enhanced via intermolecular H-bonds. Characteristic absorption
shifts of C=O groups of TLCPa/PA66 in Fourier transform infra-red spectra (FTIR) confirmed the
existence of H-bonds. Scanning electron microscope (SEM) observation showed that the shape of
TLCPa phase change in matrix with increasing TLCPa content. Mechanical properties of blends were
significantly improved by good interface adhesion and TLCPa fibrils generation.
Finite Element Analysis of Interfacial Debonding Damage in Fiber-Reinforced Ceramic Matrix Composites
Authors: Liu Chun Jun , Zhang Yue , Zhang Da Hai , Li Zhong Ping
Published: March 2009

In this paper the composite fracture process has been simulated via the finite element
method. A micromechanics model was developed to predict the stress-strain response of a SiO2f/ SiO2
composite explicitly accounting for the local damage mechanisms such as fiber fracture and
interfacial debonding. The effects of interfacial strength and fiber volume fraction on the toughness of
fiber-reinforced ceramic matrix composites were investigated. The results showed that the composite
failure behaviors correlated with the interface strength, which could achieve an optimum value for the
elevation of the composite toughness. The increase of fiber volume fraction can make more
toughening contributions.
Effect of Electrochemical Treatment on the Surface Structure and Tensile Strength of Carben Coated CVD SiC Fiber
Authors: Ji L. , Shi N.L. , Yang Rui
Published: March 2009

CVD (chemical vapor deposition) SiC continuous fiber is used as reinforcement of metal
matrix composites because of its high strength, high stiffness and elevated temperature stability. In
this work, anodic oxidation method was used to treat the surface of carbon coated SiC fiber. Then the
surface of treated fiber was compared with untreated one by scan electron microscopy (SEM), energy
dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). SiC was detected
on the surface of untreated carbon-rich coating. It is proved by XPS that SiC was transformed into
SiO2 after treatment. About 100~200nm thick oxidation layer was detected on the surface of
carbon-rich coating and the structure of double coatings formed. Because the surface of fiber became
smooth and the tensile stress on it was relaxed after treatment, the tensile strength of fiber was
improved by 8%~20% average and the dispersing ratio of it was reduced.
Effect of Mo on Properties and Microstructure of Steel-Bonded Cemented Carbide GT35 Produced by In Situ Reduction of Ilmenite
Authors: Wu Yi , Yin Chuan Qiang , Zou Zheng Guang , Wang Xin , Li Xiao Min
Published: March 2009

Steel-bonded cemented carbide GT35 was fabricated from natural ilmenite by in-situ
carbothermic reduction and vacuum pressureless sintering. The effects of Mo-doped on the
mechanical properties and microstructures of GT35 composites were investigated. That the good
mechanical properties of steel-bonded cemented carbide GT35 with 9wt% Mo were obtained at the
same sintering condition that the density reached 6.223g/cm3 and the average bending strength
reached about 1155.6MPa after heat treatment, but the hardness dropped the lowest value HRC 60.94
and the difference was not apparent with the change of Mo content. The additive of Mo is beneficial to
be refinement of carbide particle size, sphericity of grains and formation of compact composite.
In-situ reduction of natural ilmenite was a feasible way to fabricate good performance composite
GT35 with a relative low cost.
Internal Friction Behaviors of TiNi Shape Memory Alloy Fiber/Ni Matrix Composite
Authors: Xing Ting Yong , Zheng Yan Jun , Cui Li Shan
Published: March 2009

The objective of present work is to investigate the internal friction behavior of TiNi shape
memory alloy fiber/Ni matrix composite. The TiNi fiber/Ni matrix composite was fabricated by an
electroplating method using TiNi alloy fiber as the cathode and Ni plate as the anode. The internal
friction as functions of temperature and strain amplitude was measured respectively. The results
showed that the internal friction peaks of the TiNi/Ni matrix composites, which due to the martensitic
reverse transformation of the TiNi fiber, broadened with increasing prestrain level. There was a sharp
internal friction increment at the high temperature, which due to thermal expansion mismatch
between the TiNi fiber and Ni matrix and recovery stress generated. Contrast to the pure TiNi alloys,
the internal friction background of the TiNi/Ni composites increased with increasing temperature.
Furthermore, the internal friction of the TiNi/Ni composites decreased with increasing strain
amplitude measured.
Microstructure and Mechanical Properties of Low Pressure Die Cast AM50 Magnesium Alloy
Authors: Peng Li Ming , Fu Peng Huai , Jiang Hai Yan , Zhai Chun Quan
Published: March 2009

Compact AM50 alloy components were cast by Low Pressure Die Casting (LPDC)
process. The microstructure and mechanical properties of cast components were investigated under
as-cast and heat treated states. It was found that the microstructure of LPDC AM50 is composed of
α-Mg and second phases - Mg17Al12 and Al8Mn5. Compared with Gravity die casting, LPDC AM50
alloy had much coarser grains and higher density, with smaller sizes and less content of second
phases. The density of AM50 alloy by LPDC process was ρ=1.7836g/cm3, with increase of 0.45%
based on Gravity die casting and much more increase compared with high pressure die casting. The
as-cast mechanical properties by LPDC process were: σ0.2=57.8Mpa, σb=192.3Mpa, δ=8.7%. These
of Gravity die casting were: σ0.2=53Mpa, σb=173.4Mpa, δ=8.1%. UTS in LPDC increased about
20MPa, with better YTS and Elongation. Compared with that of high pressure die cast AM50, the
YTS of LPDC was much lower, with comparable UTS and Elongation. The mechanical properties of
the heat treated AM50 alloy were still in the same level of as-cast state. AM50 alloy by LPDC process
is not necessary subjected to tempering treatment.
Effect of Hf Addition on High Temperature Properties of Ir-Containing Alloy Coatings
Authors: Murakami Hideyuki , Kamiya K. , Yamaguchi Akihiro , Wu Ying Na , Kuroda Seiji
Published: March 2009

In the present study, high temperature properties of Ir-modified and Ir-Hf-modified
aluminide coatings on Ni-based single crystal superalloy TMS-82+ were discussed. They were
prepared by depositing pure Ir and Ir-Hf alloys on TMS-82+ using magnetron sputtering and
EB-PVD, followed by a conventional Al-pack cementation process. The effects of Hf addition on the
oxidation resistance and top-coat spallation resistance were investigated. Cyclic oxidation test at
1423K for 1h as one heating cycle revealed that while there is a small difference in oxidation kinetics
and spallation lives between Ir and Ir-Hf coatings, drastic difference in surface morphology was
observed. After 50 oxidation cycles the Ir-modified aluminide coating showed surface rumpling
whereas the Ir-Hf modified aluminide coatings kept the flat surface. It was also revealed that
excessive addition of Hf promoted the internal oxidation, resulting in the deterioration of substrates.
These results agree with the conventional Pt-modified aluminide coatings and Ni-Al-Hf alloys.
Suspension Development for Electrophoretic Deposition of Mullite Coating
Authors: Chen Guo Feng , Li Jing Long
Published: March 2009

In this paper, the preparation of mullite suspension for electrophoretic deposition (EPD) is
presented. It shows that the successful deposition of mullite coating is closely related to the weight
ratio of mullite powder to ethanol solvent, and the concentration of phosphate ester (PE) in ethanol
solvent, which is employed to positively charge the mullite particles in suspension. The polyvinyl
butyral (PVB) is necessary as binder in the suspension. With increasing the powder:ethanol weight
ratio, the content for the PVB in the suspension will also increase in order to make the deposited layer
adhere to the substrate. The compositions of the mullite suspension were optimized and the process
was determined based on the surface quality. It provides a new route to develop mullite coating on
SiC or Si3N4 ceramic materials for high temperature application.
Oxidation Behavior and Residual Stress in Thermally Grown Oxides of Detonation and High Velocity Oxygen Fuel Sprayed NiCrAlY Coatings
Authors: Chen Z.X. , Yuan F.H. , Zhu Shijie , Wang Zhong Guang
Published: March 2009

NiCrAlY coatings were prepared by the detonation spraying (DS) and high velocity oxygen
fuel (HVOF) spraying processes, respectively. The DS NiCrAlY coating has higher oxidation rate
than the HVOF NiCrAlY coating at 1100 oC due to its rougher surface and more mixed oxides. The
residual compressive stress in thermally grown oxides (TGO) on the DS NiCrAlY coating is higher
than that on the HVOF coating because the θ-Al2O3 to α-Al2O3 transformation causes the tensile
stress in the TGO on the HVOF coating.
Development and Oxidation Resistance of Si-Modifide MCrAlY Coatings on Nb-Base Alloy
Authors: Li Xiao Xia , Zhou Chungen
Published: March 2009

Halide-activated pack cementation and Air plasma spraying methods were utilized to
deposit Si-modified MCrAlY coatings. Nb-base alloys were coated with MCrAlY by Air plasma
spraying and followed by pack siliconizing process at 1100°C for 8h and 10h. The pack powders were
consisted of 5 Wt.℅NH4Cl、35 Wt.℅Si、60 Wt.℅Al2O3. Si-modified MCrAlY coatings have
three-layer microstructure. The outer layer was composed of NbSi2 and Nb3Ni2.4Cr1.6Si6, while the
middle layer comprised the compound of Nb、Ti、Ni、Cr、Si. The inner layer adjacent to the
substrate was silicide. Isothermal oxidation resistance of Si-modified MCrAlY coatings was tested at
1250°C in static air. Si-modified MCrAlY coatings had excellent oxidation resistance, because
continuous Cr2O3 and SiO2 scales which serve as obstacle of oxygen diffusion were formed after
oxidation.
Microstructure Evolution of Nd2O3 and Yb2O3 Co-Doped YSZ Thermal Barrier Coatings during High Temperature Exposure
Authors: Wei Qiu Li , Guo Hong Bo , Gong Sheng Kai
Published: March 2009

10mol% Nd2O3 and Yb2O3 co-doped YSZ thermal barrier coatings were produced by
electron beam physical vapor deposition (EB-PVD). Compared to the traditional YSZ coating, the
deposited coating has shown tree-like microstructure in each column. Due to this, the co-doped
coating is more porous than the YSZ coating. The microstructure evolution of the coating during high
temperature exposure at 1373 K was studied. The tree-like microstructure disappeared due to joining
of sub-grains during sintering. Thermal growth oxide (TGO) grew quickly at the first few hours and
then the growth of TGO became slow in the subsequent high temperature exposure. Cracks generated
and propagated in the ceramic top coat and along the interface of the top coat and TGO layer. Finally,
the coalescence of such cracks resulted in failure of the TBCs.
Hf Modified NiAl Bond Coat for Thermal Barrier Coating Application
Authors: Sun Li Dong , Guo Hong Bo , Li He Fei , Gong Sheng Kai
Published: March 2009

The Hf doped NiAl coatings were co-evaporated and co-deposited onto the superalloy
substrate by electron beam physical vapor deposition (EB-PVD). During heat-treatment, HfO2 was
formed on the NiAl coatings. And, Hf enriched at the interface between the coating and the
interdiffusion zone, which could prevent outward diffusion of elements in the substrate. The NiAl
coating doped with 0.5% Hf effectively improved the high temperature oxidation resistance compared
to the Hf free NiAl coating and the high Hf content coating. Also, the addition of Hf to the coating
contributed to enhancing the adherence of TGO layer to coating.
Effect of Si, Sr Additions on Microstructure and Mechanical Properties of AZ91 Alloy
Authors: Li S.B. , Zou Zhi Wen , Xiong Shou Mei
Published: March 2009

In present work, Si and Sr elements were added into AZ91 alloy and cast directly into test
samples using permanent mold. Mechanical properties of the samples at room temperature were
evaluated by tensile test and the microstructure was analyzed. The results show that β-phase
(Mg17Al12) of AZ91 alloy decreases with the addition of Si element and Mg2Si phase forms at the
same time. Irregular Mg2Si phase precipitates preferentially at the grain boundaries at a low silicon
content level. With the increase of the Si content, Mg2Si phase shows a complicated “Chinese- script”
shape distributed at the grain boundary which leads to a lower ultimate tensile strength. Subsequently,
the addition of Sr element has a remarkable effect on the form and distribution of Mg2Si phase of
AZ91-Si alloys.
Melting Temperatures of Several Oxides under Pressure
Authors: Zhang S. , Jia Shu Sheng
Published: March 2009

The melting temperature-pressure phase diagram [Tm(P)-P] for corundum (Al2O3), wustite
(FeO) and magnesium oxide (MgO) are predicted through the Clapeyron equation where the
pressure-dependent volume difference is modeled by introducing the effect of surface stress induced
pressure. The model prediction is found to be consistent with the present experimental results.