bluuebunny/crossref_metadata_2025 huggingface dataset:
Dielectric Properties of Hot-Pressed of SiCN/A3S2 Nanocomposites
Authors: Luo Fa , Zhu Dong Mei , Zhao San Tuan , Zhou Wan Cheng
Published: March 2009

A series of nanocomposites, SiCN/A3S2 ceramics, were prepared by hot-pressing method.
The nanometer SiCN powder is characterized of high dielectric dissipation. The dielectric
properties of the SiCN/A3S2 nanocomposites were investigated. XRD and SEM were conducted to
study the phases and microstructure of the nanocomposites. Compared with the pure A3S2 ceramic,
the grain size in the nanocomposites is reduced due to the addition of nanometer SiCN powder. The
relative densities of the nanocomposites are also lower than that of the pure A3S2 ceramic. Both the
real and imaginary parts of the complex permittivity of nanocomposites in X band increase as the
content of SCN powder in the samples rises obviously. When the contents of SiCN powder in
samples are same, the real and imaginary parts of the samples vary with the sintering temperature.
The tanδ of the nanocomposites reduces from 1.9 to 1.4 when sintering temperature increases from
1450OC to 1650 OC. SAED pattern reveals that structure of the SiCN in SiCN/ A3S2 sintered at
higher temperatures tend to crystallize. The real, imaginary parts and dissipation factor of the
nanocomposites sintered at higher temperature is lower than those sintered at 1450 °C.
Effect of HA Content on Mechanical Properties of Hot Drawn HA/UHMWPE Nanocomposites for Bone Substitutes
Authors: Fang Li Ming , Leng Yang , Gao Ping
Published: March 2009

Hydroxyapatite reinforced ultrahigh molecular weight polyethylene (HA/UHMWPE)
nanocomposites with HA volume fraction 0.1~0.5 are processed by twin-screw extrusion
compounding and compression molding followed by hot drawing. SEM micrographs show that HA
nano-particles are homogeneously dispersed in the highly oriented UHMWPE inter-fibrils. Tensile
tests show that the modulus increases, while the strength and ductility decrease, with the increase of
HA content. A good combination of mechanical properties can be obtained in the composite with
HA nano-particles volume fraction 0.3.
Dynamic Properties of MWNTS/Epoxy Nanocomposite Beams
Authors: Yeh Meng Kao , Hsieh Tsung Han
Published: March 2009

The dynamic properties of multi-walled carbon nanotubes (MWNTS)/epoxy
nanocomposite beams were investigated experimentally and numerically. The MWNTs/epoxy
nanocomposite beams were fabricated by hot press method. In experiment, the dynamic properties of
the nanocomposite beams, such as natural frequency, and damping ratio, were obtained. A shaker was
used to provide the vibration source at the fixed base of the specimens. The vibration signals of the
nanocomposite beams were detected by a laser sensor, and the frequency responses were obtained by
a computer-aided signal analyzer. The half power method was used to find the damping ratios of the
nanocomposite beams for each mode. In analysis, the mechanical properties of MWNTs/epoxy
nanocomposites were obtained and used in the free vibration analysis by the finite element method.
The natural frequencies and mode shapes of the nanocomposite beams were calculated numerically.
The effect of the weight percentage of MWNTs on the dynamic properties of the nanocomposite
beams was investigated. The numerical results were found to be in good agreement with the
experimental ones.
Effect of VGCF Addition to Carbon Fabric/Ep
Authors: Park Ji Sang , Kim Byung Sun , Kim Jin Bong , Kim Tae Wook
Published: March 2009

Despite of the excellent properties of carbon nanofiber, the properties of carbon nanofiber filled polymer composite were not improved as much as expected. The usual reason may be not sufficient dispersion of the nanofibers within the composites. For the improvement in the mechanical properties of composites, the carbon nanofiber reinforced hybrid composites was investigated. For the dispersion of the carbon nanofiber, the solution blending method using ultrasonic was used. The hybrid composite was manufactured by the Solution-Dip-Type prepreg manufacturing machine. This machine is consisted of resin bath, curing tower that evaporates solvent and process controller for manufacturing speed. The prepregs were cured in an Autoclave. 3 wt% of carbon nanofiber containing hybrid composite, Carbon Fabric/Ep, was tested by Universal Testing Machine. The tensile strength and modulus were improved by 25% and 35%, respectively. In-plane shear strength and modulus were improved by 45% and 78%, respectively.
Surface Defects Repairing by Polymer Coating with Low Fraction of Nano-Reinforcements
Authors: Gao Shang Lin , Mäder Edith , Plonka Rosemarie
Published: March 2009

Surface defects cause the measured tensile strength of glass and other brittle materials
significantly lower than their theoretical values. Here, we describe an on-line process to ‘heal’ surface
flaws and functionalise surface properties. A nanometer-scale hybrid coating layer based on
styrene-butadiene copolymer with mutiwalled carbon nanotubes (MWCNTs) and/or nanoclays, as
mechanical enhancement and environmental barrier layer, is applied to alkali-resistant glass fibres
(ARG). The nanostructured and functionalised traditional glass fibres with low fraction of nanotubes
or nanoclay (1 wt% in sizing) show significant improvement in both mechanical properties and
environmental corrosion resistance. We introduce a healing efficiency factor and conclude that the
coating modulus, thickness and roughness are responsible for the mechanical improvement of fibres.
Furthermore, we show that the hybrid coating layer is essential for enhanced interfacial adhesion
strength of the glass fibre reinforced cement composites.
Fatigue and Electrical Properties of CNT/Phenolic Composites under Moisture-Temperature Effects
Authors: Yip Ming Chuen , Wu Hung Yuan
Published: March 2009

Carbon nanotubes have excellent mechanical and electrical properties such as high
stiffness, light weight, heat stability, excellent heat conductivity, and excellent electrical
conductivity. This study was aimed into investigate the properties of composites consisting of adding
several different proportions of carbon nanotubes to phenolic resin, which contained tensile strength,
fatigue life and electrical properties. The experimental results showed that the electric resistance
decreases as the weight percentage of the nanotubes increases, also the tensile strength increased as
the nanotubes increased. After the different moisture-temperature circumstances and thermal cycling,
the increase of the electric resistance was compared to the pristine composites. The experimental
results hoped to be understood from the fracture surface observations by scanning electron
microscope (SEM).
Finite Element Modelling Epoxy/Clay Nanocomposites
Authors: Chia Julian Y.H. , Hbaieb Kais , Wang Q.X.
Published: March 2009

A full 3D finite element method has been used to understand how nano-clay particles affect
the mechanical properties of an epoxy/clay nanocomposite. The epoxy/clay nanocomposite has been
modelled as a representative volume element (RVE) containing intercalated clay platelets that
internally delaminates at the gallery layer upon satisfying an energy criterion, and an epoxy matrix
that is elastic-plastic. A cohesive traction-displacement law is used to model the clay gallery
behaviour until failure. For clay volume fractions >1%, clay particle interaction is observed to
develop during uniaxial tension, the nanocomposite stiffness becomes non-linearly dependent on the
clay volume fraction, and the Mori-Tanaka model overestimates the stiffness. Failure of the clay
gallery is not observed and is believed to have no influence on the ultimate tensile strength of the
nanocomposite.
Self-Healing Glass Fibres with Carbon Nanotube-Epoxy Nanocomposite Coating
Authors: Siddiqui Naveed A. , Kim Jang Kyo , Muzaffar Farjaad , Munir Arshad
Published: March 2009

This paper reports a study based on a novel concept of ‘self-healing’ coatings applied onto
the brittle fibre surface to reduce the stress concentrations and thus to improve the reinforcing
efficiency in a composite. The individual E-glass fibres as well as rovings were coated with a carbon
nanotube (CNT) reinforced epoxy composite. The tensile strengths were measured for the individual
and bundle fibres, which were treated statistically to determine the Weibull parameters and thus to
evaluate the notch sensitivity of the fibres with and without coating. The results indicate that the
tensile strength of the individual fibre increased by 10% after coating with neat epoxy. Coating
with epoxy nanocomposite containing 0.3wt% MWNT further improved the tensile strength.
However, increasing the nanotube content was not necessarily beneficial due to the formation of
nanotube agglomerates within the matrix. The tensile tests on fibre roving also showed a clear trend
of beneficial effect of nanocomposite impregnation on tensile strength. The rovings impregnated
with nanocomposite exhibited a more uniform strength distribution and higher strengths than those
impregnated with neat epoxy. Changes in prevailing failure mechanisms influenced by the epoxy
and nanocomposite coatings are identified.
Synthesis and Characterization of Polymer Nanofoams
Authors: Zhang Yi He , Li Y. , Huang Hai Tao , Ke Sha Ming , Zhao Li Hang , Chan Helen Lai Wah
Published: March 2009

In order to obtain thin film dielectric layers with very low dielectric constants for use in
microelectronic devices, polyimide nanofoamed films has been prepared from the polyimide
precursors (PMDA-ODA) and poly(ethylene oxide) (PEO) in N,N-dimethylacetamide. The
synthesization process included blending polyimide as the major phase with a minor phase of the
thermally labile PEO blocks. The foamed films were characterized by a variety of experiments
including TG and SEM, and the experimental results indicated that the labile PEO would undergo
oxidative thermolysis to release small moleculars from the matrix so as to leave voids into the
polyimide matrix. The dielectric properties of the films were studied over broad frequency ranges.
The dependences of dielectric constant on the PEO content in the films and frequency were
discussed. The films with a proper amount of PEO displayed relatively low dielectric constant
compared to the pure polyimide film. Thin film foams with high thermal stability and low dielectric
constants can be prepared using the approach.
Mechanical Properties of VGCF/PP Nanocomposites by Extrusion and Compression Process
Authors: Byun Joon Hyung , Min Kyeong Sik , Yu Yeun Ho , Um Moon Kwang , Lee Sang Kwan
Published: March 2009

This study describes a method of good dispersion and alignment of VGCFs, and examines
the effect of nanofiber content on the mechanical properties of nanocomposites. The dispersion of
nanofibers was carried out by solution blending, mechanical mixing, and sonication. Levels of 4% –
31% volume content of VGCFs were mixed with polypropylene (PP) powder, and then were
melt-mixed using a twin-screw extruder. For the further alignment of fibers, extruded rods were
stacked in the mold cavity for the compression molding. In the case of 31% volume content, tensile
modulus and strength improved by 100% and 40%, and the flexural modulus and strength increased
by 120% and 25%, respectively. The shear modulus showed 65% increase, but the strength dropped
sharply by 40%. In the transverse direction, the tensile, flexural, and shear strength decreased as more
fibers were added. The matrix modification by maleic anhydride (MAPP) increased the tensile and
flexural properties of VGCF/PP by 20% - 30% in the longitudinal direction, and 40% - 250% increase
in the transverse direction. The fiber surface treatment by plasma improved tensile and flexural
properties of untreated VGCF/PP (18 % vol) composites by 10% - 30% in the longitudinal direction,
but strength in the transverse direction decreased by 30% - 40%.
Comparison of Carbon-Based Nano Materials as Conductive Fillers for Single Layer Microwave Absorber
Authors: Kim Jin Bong , Lee Sang Kwan , Kim Chun Gon
Published: March 2009

In this paper, we have studied the permittivities of E-glass fabric/epoxy composite
laminates containing three different types of carbon-based nano conductive fillers such as carbon
black (CB), carbon nano fiber (CNF) and multi-wall carbon nano tube (MWNT). The measurements
were performed for permittivities at the frequency band of 0.5 GHz ~ 18.0 GHz using a vector
network analyzer with a 7 mm coaxial air line. The experimental results show that the complex
permittivities of the composites depend strongly on the natures and concentrations of the conductive
fillers. The real and imaginary parts of the complex permittivities of the composites were
proportional to the filler concentrations. But, depending on the types of fillers and frequency band,
the increasing rates of the real and imaginary parts with respect to the filler concentrations were all
different. At the frequency of 10 GHz, the rates in the CNF filled composite and the MWNT filled
composite were much larger then those of the CB filled composite. Between the CNF filled
composite and MWNT filled composite, however, the former showed a little higher increasing rates
than the other. These different rates can have great effect on the thickness in designing the single
layer microwave absorbers. The effect of the different rates was examined by using Cole-Cole plots;
the plot is composed of a single layer absorber solution line and permittivity lines of these three types
of composites.
Preparation of Nanocomposites Used in Slapper Detonator
Authors: Wen Yu Quan , Zhang Yi He , Su Qing Song , Zhen Wei , Chen Zhong Rui
Published: March 2009

Slapper detonator is composed of bridge foil, flyer, barrel, tamper and explosive pellet.
The function of flyer is insulation, safety and forming flyer in detonator, and it was usually
fabricated by thermal-resistant polymer film with cupper coating. In this study, nano-doped
polyimide (PI) nanocomposite films have been prepared using in-situ polymerization method
through incorporating nano silica fillers, and characterized by SEM and UV-Vis techniques. The
possibility used as flyer in slapper detonator of the nanocomposite film was also discussed.
Influence of Silicate Surface Modification on Morphology and Mechanical Properties of Nylon6/Clay Nanocomposites
Authors: Shim Jae Hun , Choi Jae Hun , Joo Jung Hiuk , Yoon Jin San
Published: March 2009

A new method was attempted to improve the interaction between nylon 6 with a
commercially available organoclay, Cloisite®25A (C25A) through modification of C25A with
3-aminopropyltriethoxy silane, 3-(trimethoxysilyl)propyl methacrylate, 3-(glycidoxypropyl)
trimethoxysilane and 3-isocyanate propyltriethoxy silane. C25A and C25A modified with the silane
compounds(TFC) were melt mixed with nylon 6. X-Ray diffraction and transmission electron
microscopy images revealed that all the TFC layers were fully exfoliated in nylon 6 matrix
irrespectively of the type of the silane compounds used for the modification. Tensile properties of
nylon 6 were most significantly improved when 3-(glycidoxypropyl)trimethoxysilane modified C25A
was incorporated. The chemical reaction between the epoxy groups and the end groups of nylon 6
raised the interfacial interaction and thus was responsible for the enhanced tensile properties.
Natural Frequency Optimization of Laminated Cylindrical Shell Subjected to Tsai-Hill Failure Criteria Constraint Using Penalty Method
Authors: Nabavi R. , Yas M.H. , Shakeri Morteza
Published: March 2009

This work deals with fundamental frequency optimization in Multi-Layered laminated
composite cylindrical shell which is subjected to strength failure criteria (Tsai-Hill) constraint.
Anisotropic cylindrical shell has finite length with simply supported conditions at both ends. Three
dimensional elasticity approaches is used to obtain the objective functioin. To perform optimization,
genetic algorithms (GAs) have been used. But GAs does not have the capability of constraint
handling. In this paper penalty method as an auxiliary method for GAs has been used to take into
accounts the constraints. Tsai-Hill criteria is used as failure constraint. Finally the results are
presented for a multi-layered composite shell.
Research of the Herringbone Microstructure of Rufescens’s Shell
Authors: Chen Bin , Peng Xiang He , Fan Jing Hong
Published: March 2009

Molluscan shell is strong, stiff, tough and shows an erose fracture surface when it is
broken. In this research, the SEM observation on a Rufescens’s shell shows that the shell consists of
aragonite layers and collagen matrix. Each aragonite layer is parallel to the surface of the shell and
consists of many thin aragonite sheets. These aragonite sheets are perpendicular to the layer where
they are located. The observation also shows that the direction of the sheets in different layer is
various and a kind of herringbone distribution is found. The maximum pullout force of the
herringbone distribution is analyzed based on its representative model, and it shows that the
herringbone distribution can markedly increase the pullout force of the distribution and improve the
fracture toughness of the shell.
Polymer Nanocomposites with Designed Interfaces
Authors: Schadler Linda S. , Lewis Sarah L. , Yang Jun Wei , Benicewicz Brian C.
Published: March 2009

This paper shows preliminary results for polymer nanocomposites consisting of
“hairy” silica particles with grafted polystyrene in polystyrene matrices of controlled
molecular weight and polydispersity. The goal of the work is to tailor the degree of wetting /
interaction between the particles and polymer by controlling the graft density and molecular
weight of the grafted polymer. This is providing an opportunity to study the properties of the
interface region and to control the bulk composite properties. We have found that the
predictions for flat brushes are qualitatively, but not quantitatively, applicable and that the
highly curved surfaces of nanoparticles present several challenges for the design of
nanoparticle interfaces. The talk will present more complete results in this system and
provide an overview of other work in our group using tailored interfaces to control
nanocomposite properties.
Thermal Vibration Characteristics Analysis of a Composite Thin-Cylindrical Shell Embedded with Shape Memory Alloy Wires
Authors: Ren Jian , Liu Q.
Published: March 2009

Thermal vibration characteristics of the composite thin-cylindrical shell embedded with
shape memory alloy (SMA) fibers are investigated. The shape memory alloy material behavior is
programmed in the form of an ABAQUS user subroutine code (UMAT), and this program is
successfully verified by using the response of pseudoelasticity and the shape memory effect (SME) at
various temperatures and stress levels. Based on the ABAQUS UMAT code, the natural frequency of
the composite thin-cylindrical shell embedded with SMA wires under thermal load and mechanical
load is calculated respectively. Then the effects of the SMA wire temperature and the content on the
thermal vibration characteristics of the structure are discussed. Numerical simulation results show
that the temperature and the volume content of the SMA wires increase the stiffness and buckling
critical load of the structure.
Fiber Bragg Grating Sensor/Piezoelectric Actuator Hybrid System for Damage Detection in Composite Laminates
Authors: Lam Pou Man , Lau Alan Kin Tak , Tam Hwa Yaw , Ling Hang Yin , Su Zhong Qing , Wong Eric Tsun Tat
Published: March 2009

In this paper, fiber Bragg grating (FBG) sensor and piezoelectric (PZT) actuator are used to
develop a hybrid system for the evaluation of delamination in glass fiber-reinforced epoxy (GF/EP)
composite laminates. The surface-bonded PZT actuator generates ultrasonic Lamb wave in the
composite laminates, while the FBG sensor, which is embedded in the composite laminates, captures
the Lamb wave signal. Wavelet analysis is introduced to extract signal spectrographic characteristics
in the time-scale domain appropriately. Since the propagation characteristics of Lamb wave is altered
by the existence of damage in the composite laminates, delamination information can be obtained
from the received signal. With the assistance of a signal generation and an acquisition system, this
methodology enables active sensing and non-destructive evaluation of delamination in the composite
laminates. Experiments have been carried out with GF/EP composite beams to examine the feasibility
of the proposed detection technique. The acquired and processed Lamb wave signals corresponding to
different delamination sizes are compared.
Characterization and Synthesis of Ni0.6Zn0.4(Fe2O4)1 Nano-Particles Using Sol-Gel Method
Authors: Li Qiao Ling , Ye Yun , Wang Yong Fei , Jing Hong Xia , Wang Ya Kun
Published: March 2009

Ni-Zn ferrite is a kind of important magnetically soft material that has been used widely
in medical signal deal and medical apparatus. So, many people are interested in both the prepare
process of Zn ferrite (especially the prepare process of nanometer ferrite) and the study of its
structure and properties. In this paper the condition in which Ni-Zn ferrite powders was prepared by
sol-gel methods was studied. The pH value, calcined temperature, calcined time were investigated.
With the designing experiment, the best condition was confirmed. The microstructures and particles
size were characterized by means of TEM、IR、XRD and so on.
Superplastic Deformation of Nano-Sized α-Sialon Ceramics
Authors: Xu Xin , Nishimura Toshiyuki , Hirosaki Naoto , Xie Rong Jun , Yamamoto Yoshinobu , Tanaka Hidehiko
Published: March 2009

In previous report, we succeeded in preparing dense nano-sized ceramics with the composition
of Y- α-sialon (m=1.35, n=0.675) by high-energy mechanical milling followed by spark plasma sintering.
The superplastic deformation of the obtained nano-ceramics was studied in this report. A good ductility of
the nano-sized ceramics has been confirmed, which arised from the nano-sized grains and large amount of
transient liquid phase. The effects of deformation on the phase and microstructural evolution were also
studied. The nano-sized grains promoted the formation of elongated α-sialon grains during post-annealing
at 1850oC for 3 h, which would strengthen and toughen the deformed ceramics.
Properties and Application of Oriented Porous SiC as Transpiration Cooling Materials
Authors: Tang Jie , Chen Yu Feng , Sun Ji Guo , Wang Hua , Liu Hai Lin , Fan Qi Cheng
Published: March 2009

This paper describes the fabrication of porous reaction-bonded SiC ceramics with radial
directed pores and the application of these materials to transpiration cooling system of rocket engines. A
special mold is designed for freeze-casting process to prepare SiC cylinders with radial directed pores.
Green bodies with well-oriented pore structure are obtained from slurry with solid loading up to 47vol%.
The pore size is in the level of several tens micron. Green bodies with various porosities are infiltrated
with different amount of liquid Si. The intrinsic permeability of each sample is measured with air as
flowing media. It is concluded that permeability has relationship with not only the porosity but also the
pore structure of samples.
Fabrication of Porous Cellular SiC Ceramics from Wood by Embedding in Si/SiO2 Powder Mixture
Authors: Ha Jung Soo , Lim Byong Gu , Doh Geum Hyun , Kang In Aeh
Published: March 2009

Wood has strongly anisotropic cellular structure with 50-80 vol% porosity. It can be converted into porous ceramics (e.g., SiC, SiC/Si, TiC, C/C, and TiO2) replicating the wood structure by various processes. Previously porous cellular SiC ceramic was prepared by reaction of wood charcoal with gaseous SiO generated remotely from an equimolar mixture of Si and SiO2. In the present work, poplar charcoal was simply embedded in the powder mixture of Si and SiO2 and heated at 1600°C for 1 h in Ar to produce porous SiC. Samples were also prepared by infiltration of Si melt (1500-1600°C, 2 h) and vapor (1700°C, 2 h) into the charcoal for comparison. Samples prepared by Si melt infiltration showed 15-52% conversion to SiC. Samples prepared by Si vapor infiltration showed severe damage such that the conversion degree could not be measured. In contrast, samples prepared by the embedding process showed full conversion to SiC (mostly β form) with good retention of the cellular structure of the original wood. The embedding process is a simple and efficient way to produce porous cellular SiC from wood.
Preparation and Properties of Al2O3-Mullite-SiC Nano-Composite by Slip Casting in a High Magnetic Field and Reaction Sintering
Authors: Saito Sho , Sakka Yoshio , Suzuki Tohru , Nakata Takeshi
Published: March 2009

We have demonstrated that textured Al2O3-mullite-SiC nanocomposites can be fabricated
by slip casting followed by partial oxidation – reaction sintering of mixed suspensions of Al2O3 and
SiC powders in a high magnetic field. The sintered density was changed by the degree of oxidation at
1200 and 1300. The degree of orientation of alumina in the nanocomposite was examined on the
basis of the X-ray diffraction patterns and scanning electron micrographs. It is confirmed that
alumina-oriented nanocomposites were fabricated. The three-point bending strength at room
temperature was observed for the nanocomposites.
Effects of Rapid Heat Treatment on Microstructure and Mechanical Properties of Ti2AlC/TiAl Composite
Authors: Yue Yun Long , Wu Hai Tao , Wu Wei Bing , Yin Hai Yan
Published: March 2009

In this paper Ti2AlC/TiAl composites were in-situ fabricated by spark plasma sintering (SPS)
and then the effects of rapid heat-treatment on microstructure and mechanical properties of Ti2AlC/TiAl
composites were investigated. After rapid heat-treatment the microstructure of TiAl matrix was
significantly transformed from the near γ microstructure to duplex microstructure. Ti2AlC particles
effectively refined the γ phase grains and the α2/γ lamellar colony microstructure. For the Ti2AlC/TiAl
composite after rapid heat-treatment at 1200°C, the bending strength and fracture toughness reached
956.8MPa and 22.8MPa·m1/2, respectively.
Microstructure and Phase Composition of (Ce, Mg)-PSZ Ceramics
Authors: Shen Zhi Ping , Cai Shu , Dong Zhen
Published: March 2009

Magnesia, ceria partially stabilized zirconia (Ce,Mg)-PSZ ceramics with net shape microstructure are prepared using a processing method similar to that of conventional Mg-PSZ ceramics, then heat-treated at 1500°C for different time. Microstructure and phase composition of (Ce, Mg)-PSZ samples with different amount of CeO2 doped were investigated using SEM and X-ray diffraction. The addition of CeO2 could impede the formation of monoclinic phase and inhibit the growth of cubic grains. A microstructure with net-shape cubic grains, in which tetragonal precipitates interweave to a nanoporous structure is obtained by adding 4∼8 mol% CeO2 in 10mol% MgO doped zirconia matrix and then heat treatment at 1500°C for different time. The precipitate morophology might be related with the addition of CeO2 and the heat treatment temperatures.
Synthesis, Characterization of Perhydropolysilazane and its Application in the Preparation of 3D SiO2f/Si 3N4 Composites
Authors: Qi Gon Jin , Zhang Chang Rui , Hu Hai Feng , Cao Feng , Wang Shao Qing
Published: March 2009

Perhydropolysilazane was synthesized by the ammonolysis of dichlorosilane-pyridine adduct, and used as precursor to prepare three-dimensional silica fiber reinforced silicon nitride matrix composites via preceramic polymer infiltration and pyrolysis at 1073Kin anhydrous ammonia atmosphere. The polymer-derived ceramic matrix was amorphous near-stoichiometric silicon nitride with an empirical formula of SiN1.34O0.02C0.01H1.21. The as-received composites were amorphous with a high density of 1.96g/cm3 after five infiltration-pyrolysis cycles. The process was successful to fabricate dense silicon nitride matrix composites reinforced by three-dimensional silica fiber due to the low viscosity, good wettability and high ceramic yield of perhydropolysilazane.
Tensile Behavior of Aluminum Matrix Composites Reinforced by Aluminum Borate Whiskers and Magnetic Ceramic Particles
Authors: Li Gang , Wang Liang , Fei Wei Dong
Published: March 2009

Aluminum borate whiskers and magnetic ceramic particles (NiFe2O4 or Fe3O4) reinforced aluminum matrix composites were synthesized by a squeeze casting technique. Microstructures were observed using scanning electron microscopy (SEM). The tensile strength and tensile yield strength of the as-cast composites containing NiFe2O4 particles were higher than that of composites containing Fe3O4 particles. The tensile yield strength of the thermomagnetically treated composites was higher than that of the as-cast or the thermally treated composites. The effects of the magnetostrictive property of Fe3O4 or NiFe2O4, the interface and the thermal residual stresses on tensile behaviors of the composites with different treatments were discussed in this paper.
Effect of PCS Pyrolysis Process on C Fiber in Cf/SiC Composite
Authors: Zhu Yun Zhou , Yuan Ming , Huang Zheng Ren , Dong Shao Ming , Jiang Dong Liang
Published: March 2009

3-D braided C fiber preform was used to reinforce SiC matrix by polymer infiltration and pyrolysis (PIP). The effect of PCS pyrolysis process on the uncoated carbon fiber was studied. During the pyrolysis, amorphous SiCxOy and some free silicon yielded. The Si element diffused into the C fiber from the matrix because of the concentration gradient at high temperature and destroyed the intrinsic structure of the uncoated C fiber. At the same time, the free Si reacted with the uncoated C fiber. Thus, strong bonding between the fiber and matrix was formed. As a result, bending strength of the composite was decreased.
Effect of Oxygen on the Mechanical Properties of Polymer-Derived Si-Al-C-O Fibers
Authors: Zheng Chun Man , Li Xiao Dong , Yu Yu Xi , Zhao Da Fang , Cao Feng
Published: March 2009

Due to the introduction of oxygen that works to keep the shape of the fibers and enhance the
ceramic yield during high temperature pyrolysis, air-curing is a critical step during the preparation of the
polymer-derived Si-Al-C-O fibers (KD-A). In this work, to investigate the evolvement of oxygen in the
fibers and the influence of oxygen on the mechanical properties of the resulted KD-A fibers, FT-IR, TGA,
XRD, SEM and element analysis were performed on the air-curing process of polyaluminocarbosilane
(PACS) fibers and the pyrolysis process of the cured PACS fibers. The results showed that the oxygen in
the cured PACS fibers was originated from aluminum aletylacetanate (Al(AcAc)3) and the air-curing
process, which could be regarded as a constant mass during the pyrolysis. In addition, it was found that the
mechanical properties of the achieved KD-A fibers were greatly effected by the amount of oxygen in the
fibers due to its inhabiting the crystallization of silicon carbide. And the oxygen content which leaded to
the KD-A fibers with the highest tensile strength was found to be 8~10%.
Effect of Aluminium Sol on Microstructure and Properties of Corundum-Mullite Ceramic
Authors: Cheng Ben Jun , Guo Xing Zhong , Li Li , Li Dong Yun
Published: March 2009

The effect of aluminium sol on the properties and microstructure of corundum-mullite ceramics was investigated. The sample with 1.5 wt% aluminium sol possessed higher room-temperature and high-temperature strengths, while the sample with 3 wt% aluminium sol had higher bulk density, lower apparent porosity and better thermal shock resistance. Aluminium sol not only acts as a binder instead of some polyvinyl alcohol (PVA), but also reacts with silica to form mullite, which improves the properties and microstructure of the ceramics by increasing corundum and mullite phases.
Performance Analysis and Experimental Verification for FBG Sensors Applied for Smart Structure
Authors: Chen Xi Yuan , Fang Lin
Published: March 2009

Among a variety of fiber sensors, the fiber Bragg grating (FBG) sensor has numerous
advantages over other optical fiber sensors. One of the major advantages of this type of sensors is
attributed to wavelength-encoded information given by the Bragg grating. Since the wavelength is an
absolute parameter, signal from FBG may be processed such that its information remains immune to
power fluctuations along the optical path. This inherent characteristic makes the FBG sensors very
attractive for application in smart material structure, health monitoring field et al. But FBG sensors are
sensitive to temperature and strain simultaneously; it is necessary to analyze the characteristics of
temperature and strain of FBG applied for smart structure. Short overview of the FBG sensing principle as
well as theoretical analyses is presented at first; then the paper proposes a simple, convenient, and low
cost experimental method to verify the performance of FBGs. The improved high-accuracy experimental
instrument of thermal deformation, which consists of an accurate temperature controlling and measuring
subsystem, supporting and adjusting subsystem, collimating and positioning subsystem and fine motion
and measuring sub-system, is simply introduced. The proposed experimental method involves bonding
one uniform FBG to the center of the pole, which is about 89.5mm long; another FBG temperature sensor
is free in the temperature-control box. The temperature in the box is -20°C-+50°C is adjusted according to
experimental schedule. The characteristics of the FBG are analyzed by actual datum, which are
simultaneously collected by a PC through a FBG interrogator. Comparing the data of FBG bonded to the
pole with another FBG temperature sensor in the free state, the characteristics of the temperature and the
thermal strain of the FBG can be obtained. The experimental result shows the FBGs used to the smart
material have good agreement characteristics with theoretical calculation of the FBGs.
Slip Casting of Green Compact of SiAlON Multiphase Ceramics from River Sand
Authors: Xu Bin , Xu Li Hua , Cheng Ke , Yao Yun
Published: March 2009

Green compact containing Yellow River sand and several additives was prepared by slip casting and the as-made compact was used to synthesize SiAlON multiphase ceramics by carbothermal reduction nitridation. The processing parameters of slip casting including the type and concentration of dispersant, solid loading, ball milling time, pH value and particle size distribution were optimized by orthogonal experiments. The results indicated that the raw materials could disperse uniformly in the suspension under the use of the mixed dispersant of skip liquid (SL, PT) and sodium carboxymethylcellulose (CMC). The green body with high bulk density of 1.86 g·cm-3 was obtained. After sintered in flowing N2, the compact could transform to SiAlON multiphase ceramics.
Synthesis and Structure of Sol-Gel Derived PST/Bi2Ti2O7 Composite Thin Films
Authors: Zhao Yong Lin , Du Pi Yi , Weng Wen Jian , Han Gao Rong
Published: March 2009

PST/Bi2Ti2O7 composite thin films were prepared by sol-gel method through heavily doping
Bi3+ into lead strontium titanate (PST). The film with mono pyrochlore phase of Bi2Ti2O7 was also
fabricated by controlling the Ti content in precursors. XRD, SEM and impedance analyzer measured the
phase status, morphology and dielectric properties of the thin films, respectively. As a result, in the
composite thin films, there was some Pb and Sr dissolved in Bi2Ti2O7, and the amount of dissolving ions
decreased with the reduction of their composition in precursors. Bi4Ti3O12 impurity in crystalline
Bi2Ti2O7 was due to the instability of Bi, and excess Ti in stoichiometry could make the film maintain to
be mono pyrochlore phase. PST/Bi2Ti2O7 composite thin films had lower permittivity and lower dielectric
loss than mono PST thin films.
High Temperature Creep Strength of Si3N4-Y2Si2O7 Ceramics by Stress Relaxation Based on a New Interpretation Model
Authors: Hong Zhang Lian , Yoshida Hidehiro , Sakuma Taketo
Published: March 2009

A new interpretation model, instead of classical Kohlrausch-Williams-Watt (KWW) equation, was applied to interpret stress relaxation behavior of Si3N4-Y2Si2O7 ceramics. Results revealed that the new model could obtain reasonable relaxation plastic viscosity and viscoelastic viscosity under testing temperature range of 1300°C~1575°C. From the plotted curve of viscosity vs 1/RT, an activation energy change occurred around 1500°C was found for both plastic viscosity and viscoelastic viscosity curves. This change, which indicated the microstructure change, was in good agreement with the significant decrease of high temperature strength retention property.
A Study on the Grinding Performance of Y-TZP/Al2O3 Ceramics
Authors: Yu Tian Lai , Yang Zheng Fang , Li Jin You , Huo Wei Rong
Published: March 2009

The correlation between machining performance and mechanical properties of Y-TZP/Al2O3 ceramics with different mechanical parameters was investigated. The grinding experiments indicated that the flexural strength had a definite influence on machining performance of samples. The higher the flexural strength was, the more difficult the sample was to be ground. XRD analysis showed that an increasing amount of the monoclinic ZrO2 would reduce the flexural strength of the samples. As a result, the grinding force that the samples underwent also decreased.
Preparation and High Temperature Performance of β-Sialon Bonded Corundum Multiphase Material
Authors: Sui Wan Mei , Luan Shi Jun , Song Ran Ran
Published: March 2009

β-Sialon bonded corundum multiphase ceramic refractory was prepared by the method of
carbothermal reduction and nitridation reactions of clay mineral doped with corundum particle phase.
The high-temperature oxidation resistance and the thermal-shock resistance behaviors of the material
were tested and investigated. The results show that the oxidation reaction history at 1573K can be divided
into two reaction kinetic phases. The circle times of the thermal-shock resistance ($=1473K) reached to
more than 200 times and the thermal shock failure is not a brittle rupture but a desquamate damage.
FEM Analysis on Thermal Stress of Desulphurization Injection Lance
Authors: Qi Jian Qiang , Huang Yong , Ouyang Shi Xi , Li Nan , Li Jiang , Wang Chang An
Published: March 2009

By means of a finite element method model, the effects of property parameters of refractory on thermal stress of injection lance have been studied. The results show that the maximum thermal stress increases with the improvement of thermal conductivity and elastic modulus of refractory, while it decreases at first and then increases with the improvement of the coefficient of expansion of refractory.
Factors Affecting the Pore Size in Porous Hydroxyapatite Produced by Stir-Froth-Polymerization Method
Authors: Zhang Jie , Ning Xiao Shan , Xiao Qun Fang , Yang Lei , Chen Ke Xin , Zhou He Ping
Published: March 2009

Stir-froth-polymerization is a novel technique for producing highly porous ceramics, in which
bubbles are formed by a mechanical frothing in aqueous slurry of ceramic powders. Many work had be
done about the porosity, the permeability and the mechanical strength of the porous ceramics derived
from this method, but there are still a lot of things remain unclear. This paper focuses on the mechanism of
frothing, and the influence of parameters in the mechanical frothing. It was found that the stir time, the stir
speed and the viscosity of the slurry have influence on the average cell-size and the distribution of them
respectively. The average cell-size can be controlled in the range from 60 to 160 μm by adjusting the
parameters.
Hydroxyapatite Coatings Deposited on Titanium Substrate by Pulsed Laser Deposition
Authors: Liu Fu , Song Ying , Wang Fu Ping , Igarashi Kaoru , Shimizu Tadao
Published: March 2009

Hydroxyapatite (HA) coatings were deposited on titanium substrate by means of pulsed laser
deposition (PLD) with Nd:YAG laser. Deposition was carried out at 20 Pa of water vapor atmosphere and
at room temperature. An Nd:YAG laser operating at a repetition rate of 10 HZ was used for deposition. In
above deposition condition, the HA coatings deposited by PLD at room temperature are amorphous phase,
and Ca/P ratio in HA coatings decreases with increasing water vapor pressure. The amorphous HA
coatings were recrystallized after hydrothermal treatment at 190°C for 10 h. The bonding strength of the
HA coating to the Ti substrate is up to 19.6 MPa. The structure and morphology of samples were
characterized by X-ray diffraction, Fourier transform infrared reflection specterophotometry, scanning
electron microcopy. The atomic ration of Ca and P was semiquantitatively determined by electron probe
micro analyzer.
Upconversion Emission of Infrared Excited Er3+-Doped Transparent Glass Ceramics Containing CaF2 Nano-Crystals
Authors: Chen Da Qin , Wang Yuan Sheng , Yu Yun Long
Published: March 2009

Upconversion luminescence of Er3+-doped SiO2-Al2O3-CaO-NaF-CaF2 transparent glass ceramics under 980 nm excitation was investigated. XRD and TEM experiments revealed the homogeneous distribution of CaF2 nano-crystals among the glassy matrix. Intense red upconversion signal was recorded and its intensity increased with the increasing of heating temperature and Er3+-doping level at the range of 0.1 to 1.0 mol%. When Er3+ doping reached 2 mol%, the concentration quenching effect appeared. All these results could be due to the incorporation of Er3+ ions into precipitated CaF2 nano-crystals. The quadratic pump power dependence of the upconversion luminescence intensity indicated that the transition mechanism of the red emission was due to two-photon absorption processes.
A Novel Hydroxyapatite Carrier for Enrichment of Hydrocarbon Degradation Bacteria
Authors: Yang Lei , Zhang Zhen Yi , Ning Xiao Shan , Li Guang He
Published: March 2009

In this paper, a novel and highly efficient hydroxyapatite (HA) carrier for cultivating hydrocarbon degradation bacteria (HDB) is introduced. The HA particles synthesized through a sol-gel method and different heat treatments were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET method. The microbial amount and activities of HDB cultivated on HA carriers were quantitatively investigated in order to assess their enriching capabilities. The results showed that HA synthesized at 550°C and the one without calcination could enrich HDB 3 and 2 magnitude orders more than the activated carbon, respectively. Mechanisms of bacterial enrichment on HA and activated carbon were also studied, and it is believed that the high bioactivity and the surface morphology of HA were responsible for the efficient reproduction of HDB. It is concluded that HA is a potential candidate to replace the conventionally used activated carbon as a novel carrier applied in the filed of bioremediation for oil contaminated soil.
Photo-Catalytic Activity of Fe3+/Sn4+ Co-Doped Titanium Dioxide Nano-Crystalline Thin Films for Methyl Orange Degradation
Authors: Di Yun Ping , Zhang Wen Li , Xu Li Hua , Wang Chang An , Shi Ren Bin
Published: March 2009

The uniform and transparent nano-crystalline thin films of pure and co-doped with Fe3+/Sn4+
titanium dioxide photo-catalysts were prepared via sol-gel dip-coating process, and were loaded firmly on
the surface of glass substrates. The structure and surface morphology of films were characterized by X-ray
diffraction (XRD) and atomic force microscopy (AFM). In particular, the photo-catalytic activity of films
was measured by ultraviolet-visible (UV-VIS) spectrophotometer. Methyl orange was used as a model
compound to study the photo-catalytic activity of films. The effects of the concentrations of doping ions
and the number of layers on photo-catalytic degradation of methyl orange solutions were investigated.
Experimental results showed clearly that the co-doping of iron and tin ions exhibited a synergistic effect,
which increased significantly the photo-catalytic activity of titanium dioxide. Especially, the
photo-catalytic activity of nano-crystalline titanium dioxide thin films co-doped with 0.1 mol%Fe3+ and
11.41mol%Sn4+ was 2.0 times higher than that of those un-doped for photo-degradation of methyl orange
solutions under the 125W self-ballasted fluorescent high-pressure mercury lamp irradiation.
Photocatalytic Properties of Nanocrystalline Tin Oxide Synthesized by Using Molten Boric Acid as a Flux
Authors: Li Lin Yan , Chen Song Zhe , Xu Sheng Ming , Xu Gang
Published: March 2009

Nanocrystalline tin oxide (S1) was prepared by using molten boric acid as a flux and was
characterized by XRD, TEM, and BET analysis. Its photocatalytic activity under UV excitation was
evaluated by the photodegradation of methylene blue in water and compared to that of the well-known
P25 (TiO2) and SnO2 powder (S2) synthesized from hydrothermal system without the participation of
H3BO3. It has been revealed that S1 exhibits similar photocatalytic activity to that of P25 powder and
better than that of S2. The high photocatalytic activity of S1 is most likely to be originated from its small
particle size and the boron-doping in the crystal lattice.
Effect of CeO2 Supports on CO Oxidation Activity of Pd-Cu Catalyst
Authors: Zhang Yu Jun , Zhang Jing Chao , Tan Sha Li , Tan Xun Yan
Published: March 2009

Nanometer CeO2 with the mean size of 15 nm is prepared by sol-gel method, and the CO
catalytic oxidation activity of Pd-Cu catalysts with three kinds of CeO2 supports was studied. The results
show that nanometer CeO2 supported Pd-Cu catalyst gives highest activity for CO oxidation. It can
maintain CO complete conversion at about 40°C.
Nano-Scaled Anatase Phase Titanium Oxide Converted from Ammonium Oxotrifluorotitanate Prepared by Aqueous Solution of Ammonium Hexafluorotitanate and Boric Acid
Authors: Lee Ming Kwei , Shih Tsung Hsiang , Shih Chung Min
Published: March 2009

Nano-scaled particle of anatase phase titanium oxide was obtained from the conversion of ammonium oxotrifluorotitanate by thermal treatment in oxygen. The crystal of ammonium oxofluorotitanate was grown on glass at 40oC with an aqueous solution of ammonium hexafluorotitanate and boric acid. The titanium oxide was obtained from the conversion of ammonium oxotrifluorotitanate by thermal treatment in oxygen. The size of nano-scaled anatase titanium oxide increases with the temperature of thermal treatment, and the size distribution is from 10 to 30 nm corresponding to the thermal temperature from 300 to 1000oC. The photocatalytic activity of the nano-scaled titanium oxide was demonstrated by the photo-deposition of copper in the solution of copper nitrate and sodium oxalate. The photocatalytic activity for the sample treated thermally at 800 oC is 1.3 times higher than that of commercial P-25.
The Preparation of Alumina Nanopowders from Solution Derived Precipitates through Polymer Gel Method
Authors: Kim Ji Kyung , Yoon Seog Young , Park Hee Chan , Park Hoy Yul , Seo Geum Seok , Park Seong Soo
Published: March 2009

Non-aggregated nanoscale α-Al2O3 powders with average size ranging from 7 to 20 nm were prepared successfully at various conditions with the use of the hydrated aluminum sulfate extracted from kaolin by polyacrylamine (PAA) gel method. The calcination temperature was relatively lower about 100°C, compared to conventional solid-state reaction. It revealed that PAA worked as a chelating agent to disperse the Al3+ ions homogeneously, and the size of alumina nanoparticles could be controlled by varying the concentration of crosslinking agent.
SnO2 Nanowires with Branched Structures Synthesized by Thermal Evaporation of Sn Powders
Authors: Kim Hyoun Woo , Shim S.H.
Published: March 2009

Branched SnO2 nanowires were prepared by heating Sn powders. SEM images indicated that the single branched nanowires had diameters in the range 50-300 nm. XRD and SAED analysis revealed that the SnO2 nanowires were crystalline with tetragonal rutile structure. PL spectrum showed visible light emission.