bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Approach for Determination of Backward Extrusion Strain Energy on AlCu5PbBi
Authors: Barisic Branimir , Grizelj Branko , Plancak M.
Published: March 2009

In the paper, firstly on the basis of different theoretical methods and by means of
different strain determining criteria the analytic modeling of backward extrusion process was done.
Analyzed analytical models are derived directly from the mathematical description of the backward
extrusion physical phenomena and their mathematical description has been presented. Afterwards,
numerical modeling of strain energy by means of ABAQUS 6.4.1. software [1] was done. Also,
stochastic modeling, founded on the statistic processing of experimental data according to the
mathematical theory of experimental design, has been examined. For establishing of process strain
energy, the second order stochastic model has been introduced. Analytic, numerical and stochastic
research and experiments were performed according to central composite design (type CCC). As
industrial case, the material AlCu5Pb Bi was chosen. The power law which describes material
compression properties is obtained as 334.33 . = ⋅ϕ 0.192 f k The extrusion strain energy is dependent
on the change in section size, friction coefficient, and material properties. Because of that, these
parameters were varied variables at the all points of CCC design. The diameter of workpiece used
in this design was set predetermined as industrial case, but both coefficient of friction and wall
thickness of workpiece has been varied according to experimental design. The best results in
modeling were derived by means of stochastic modeling, and the best strain energy model in the
form 2 2 W = -1111.82 − 88.7 ⋅μ − 3200 ⋅μ + 625 ⋅μ ⋅ s + 816.43 ⋅ s − 42.25 ⋅ s has been obtained.
FE Simulation of Extrusion to Produce a Thin-Walled Wide Profile through a Spreading Pocket Die
Authors: Fang Gang , Zhou Jie , Duczczyk Jurek , Wu X.K.
Published: March 2009

In the present case study, finite element (FE) simulation was performed to evaluate the
design of a spreading pocket die by analysing the metal flow during the extrusion of the 6061 alloy to
produce a thin-walled wide profile for ground transportation applications. The results obtained from
the FE simulation were in good agreement with those from industrial extrusion trials. The velocity
and temperature non-uniformities on the profile cross section, revealed from the FE simulation,
suggested the die bearing area for die correction. The FE simulation also showed that ram speed had
little influence on the velocity non-uniformity but a marked effect on the temperature and temperature
distribution of the profile. In the case of extrusion through the spreading pocket die, more heat
dissipation from the hotter billet to the die took place, especially when ram speed was low. Therefore,
to reach a temperature sufficient for the dissolution of Mg and Si, ram speed must be raised. The FE
simulation in the transient state of the extrusion process could give an indicative ram speed for trial
extrusion to reach a sufficiently high temperature for the solution treatment on the one hand and to
avoid hot shortness on the other hand. It also showed that ram speed had a moderate effect on the
breakthrough pressure. Therefore, in the selection of ram speed, attention should be paid to its effect
on the maximum profile temperature and temperature distribution.
Preparation of 3D C/SiC-Cu Composites via Precursor Pyrolysis and Property Investigation
Authors: Wang Qi Kun , Hu Hai Feng , Chen Zhao Hui
Published: March 2009

A novel composite, 3D C/SiC-Cu, which contained copper as transpiration agent, was designed
and prepared. The influence of copper contents (2.18, 4.86, 6.53vol %) upon the mechanical and
anti-ablative properties was investigated. The flexural strengths of three composites were over 450MPa,
and fracture toughness over 15.0MPa•m1/2. After being ablated for 35 seconds in flowing oxyacetylene
torch environment, the composites remained integral, and the flexural strength and strength retention ratio
of the composite increased with the copper content increase. The maximum recession rate of the samples
in oxyacetylene torch test was as low as 0.0490mm/s.
Feasibility Analysis of Self-Reactive Spray Forming TiC-TiB2-Based Composite Ceramic Preforms
Authors: Liu Hong Wei , Zhang Long , Wang Jian Jiang , Du Xin Kang
Published: March 2009

A new near-net-shape technology, namely, self-reactive spray forming, to prepare ceramic preforms with low cost was proposed by combining the self-propagating high-temperature synthesis (SHS) with the metal spray forming. The feasibility of the technology was illustrated. And TiC-TiB2 -based structural ceramic was prepared by the new technology. The microstructure of the self-reactive spray formed preforms was analyzed. It was shown that the self-reactive spray formed preforms are composed of four kinds of structure, which takes on the characteristics of rapid solidification. They are griseous continuous base phase TiC0.3N0.7, black columnar grain TiB2 with the size of 100nm-1μm, white by-product phase TiO2 distributing along the boundary of the base phase, and a few of black anomalous pores respectively.
Tissue Engineering Scaffolds of Bioceramics and New Bone Growth
Authors: Tian Jie Mo , Dong Li Min , Wang Chen , Guo Zhi Ping , Zhang Chao Zong , Zan Qing Fen , Wang Xian Gang
Published: March 2009

The paper describes β-TCP/DCHA and mineral phase structural bioceramics(CHA) as well as
their 3-D structures, bioactivity, degradability and introducing new bone growth. FT-IR, XRD, SEM and
Micro-CT were used to evaluate β-TCP/DCHA and mineral phase structural ceramics before and after
implantation. Osteoblasts were immersed in the bioceramics and implanted in the rabbit femora. The
experimental results showed that new bone grown in β-TCP/DCHA, and scaffolds were degraded with
new bone formation and growth. The results indicated that β-TCP/DCHA was a better tissue engineering
material. A kind of biomaterial (β-TCP/CHA) can be used for in situ formation or in vitro individuation
formation. The experimental results indicated that β-TCP/CHA possessed better osteoblast affinity.
Osteoblasts can adhere, proliferate and grow better on the material. The experiments in vivo showed the
materials bonded with osseous tissue. The implants were degraded obviously after 6 months, and new
bone replaced degradation materials.
Preparation and Characterization of the Porous Hydroxyapatite/Silk Fibroin Composite Scaffolds with Interconnected Ducts
Authors: Wang Jing , Li Mu Qin , Meng Xiang Cai , Wen Guang Wu
Published: March 2009

Porous hydroxyapatite (HA) bioceramic matrix with interconnected ducts was obtained using a
porogen burnout technique at 1200°C. The HA/silk fibroin (SF) composite scaffolds were developed with
the SF sponges formed inside the pores and ducts of the bioceramics by first introducing HA/SF slurries
into the pores and ducts followed by a freeze-drying process. Phase components and morphology of
materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM),
respectively. Porosity was measured by Archimedean method. Compressive strength was also measured.
The simulated body fluids (SBF) experiments were conducted to evaluate bioactivity. The results show
that hydroxyapatite is the main phase compositions after sintering at 1200°C. The porosity of composite
scaffolds reaches 70%~80%. The sizes of pores and ducts of HA matrix range from 150μm to 400μm and
the pore sizes of SF sponges formed inside the macroporous structure of bioceramics are approximately
100μm,a structure favorable for bone tissue in-growth. The compressive strength of the composite
scaffolds is greatly improved in comparison with that of HA matrix. In the SBF tests, a layer of randomly
oriented apatite crystals form on the scaffold surface after sample immersion in SBF. The cell culture
experiments show that the osteoblast cells are attached and proliferated on the surface of the composite
scaffold, which suggest good bioactivity and cellular compatibility of the composite material.
Preparation of Hydroxyapatite Coatings on Carbon/Carbon Composites by a Hydrothermal Electrodeposition Process
Authors: Zhu Guang Yan , Huang Jian Feng , Cao Li Yun , Zhou Min , Wu Jian Peng
Published: March 2009

Hydroxyapatite (HAp) coatings were prepared by a hydrothermal electrodeposition method on
Carbon/carbon (C/C) composites. The as-prepared HAp coatings were characterized by XRD and SEM
analyses. The influence of hydrothermal temperature on the phase and surface microstructures of HAp
coatings and the corresponding deposition kinetics were particularly investigated. Results show that with
the increase of hydrothermal temperature, the crystallinity, density and homogenous of the prepared HAp
coatings are improved. The deposition rate also increases with the increase of hydrothermal temperature.
The deposition activation energy of HAp coatings by the hydrothermal electrodeposition process is
calculated to be 25.89 kJ/mol.
Biological Performance of Dental Biphasic Calcium Phosphate Ceramics Modified by Cold Plasma
Authors: Su Bao Hui , Su Jing Chun , Ran Jun Guo , Su Bao Yue
Published: March 2009

HA/ß-TCP is one kind of important bone tissue engineering scaffold materials. In order to
improve the biological performance of materials, HA/ß-TCP ceramics were modified by the cold plasma
technique in this paper. The biological performances of treated materials were evaluated by the results of
bone-like apatite formation in SBF, the coculture of the C2C12 cell line and HA/ß-TCP, cell proliferation
experiments, observations of the electron microscopy and fluorescence staining and the animal
intramuscular implantation experiments. The results showed that after immersion, compared with
untreated HA/ß-TCP, treated materials were more conducive to form bone-like apatite; modified
HA/ß-TCP could promote the cell proliferation more; the cells grew in the course of nature on the treated
scaffold and modified HA/ß-TCP had better bone-forming performance in vivo. It was concluded that
modified HA/ß-TCP had better biological performance; the cold plasma technique could improve the
biological performance of dental biphasic calcium phosphate ceramics.
Dielectric Properties of Zr-Doped CaCu3Ti4O12 Ceramics
Authors: He Yong , Chen Ke Pi , Liu Dong Yu , Liu Zong De
Published: March 2009

CaCu3(Ti1-xZrx)O12 ceramics (x = 0.02, 0.04, 0.06, 0.08) were prepared by the conventional solid-state reaction method. Phase compositions, microstructure and dielectric properties were examined by XRD, SEM and impedance spectroscopy, respectively. The experimental results indicated that there is no obvious effect on microstructure characteristic by substituting Zr4+ for Ti4+. It was found that the values of the dielectric constant for all of the samples dropped into the order of 102, which is significantly lower than the order of 105 that of normally reported in the literature. It was suggested that the presence of impurity phases played an important role for the degeneracy of dielectric properties.
Characterization of Laser Cladding WC-Ti Composite Coatings
Authors: Zhang Jian Bin , Fan Ding , Zheng Min , Sun Yao Ning , Zheng Yu Feng
Published: March 2009

The applications of titanium and titanium alloys under severe wear conditions are highly
restricted due to their low hardness and poor tribological properties. To improve the hardness and wear
resistance, laser cladding of commercial purity titanium was carried out with a 5 kW continuous wave
CO2 laser. WC powders and Ti powders were mixed for cladding in different proportions. The phases of
clad layer were characterized by scanning electron microscopy, X-ray diffractometer and energydispersive
X-ray spectroscopy. The mechanism of the reaction between melted WC and Ti is discussed.
A Promising LaSmZr2O7 Ceramic with Pyrochlore Structure for Thermal Barrier Coatings
Authors: Xu Qiang , Pan Wei , Wan Chun Lei , Qi Long Hao , Miao He Zhuo , Wang Fu Chi
Published: March 2009

Based on La2Zr2O7 ceramic for thermal barrier coatings, LaSmZr2O7 ceramic doped with samarium ion was successfully prepared using solid state reaction method. The pellets were sintered at 1600°C for 10 hours in air. The phase structure, thermal conductivity and thermal expansion coefficient of LaSmZr2O7 ceramic and La2Zr2O7 ceramic were measured by XRD, laser-flash device, high-temperature dilatometry, respectively. The results show that the crystal structure of LaSmZr2O7 ceramic is not affected by the doped samarium ion in the zirconium lattice. The thermophysical results show that the thermal conductivity of the LaSmZr2O7 ceramic is lower than that of La2Zr2O7 ceramic, while the thermal expansion coefficient is higher than that of La2Zr2O7 ceramic. These results indicate that LaSmZr2O7 ceramic or Ln2Zr2O7 ceramics doped with other rare earth ions could be candidate materials for future thermal barrier coatings.
DC and AC Electrical Properties of Sr2-xLixFeMnO6 Compound
Authors: Sellai A. , Widatallah H. , Yassin O.A. , Elzain M.
Published: March 2009

The variations of dc conductivities (σ) of the Sr2-xLixFeMnO6 double perovskite system over a
range of temperatures (100 ~ 300 K) and for several concentrations (0≤ x ≤ 0.4) of incorporated Li+ ions
are well described by the equation σ = (B/T) exp(−Ea/kT) and show a decrease with decreasing
temperature for a given doping. At a given temperature, σ tends to decrease with increasing x. The derived
activation energy shows a gradual increase with x with a range of values that are lower than what is
usually reported. The measured ac impedance is used to extract the relaxation frequencies as a function of
composition and temperature.
Molecular Dynamics Study of Diffusion Behavior in Amorphous Silica with Hydroxyl Group
Authors: Zhang Fan Wei , Zhu Qui Ang , Ding Yuan Fa , Zhang Yue , Zhang Da Hai , Li Zhong Ping
Published: March 2009

Molecular dynamics simulations are performed to research the diffusion behavior of
amorphous silica with hydroxyl group. Muliken analysis is employed for the determination of initial
charge status of simulated systems with various hydroxyl contents. Modified BKS potentials for the
interactions between introduced hydroxyl groups and other atoms, are adopted in the present molecular
dynamics simulations. Short-range atomic arrangement and self diffusion coefficients of hydroxyl-doped
amorphous silica systems are calculated and hereafter compared with those of pure amorphous silica. The
calculation results suggest that the doped hydroxyl groups play an important role for the mobility of atoms
within the system, which can be employed to the theoretical interpretation of the oxidation process of the
ceramics such as silicon nitride.
Application of Improved Back-Propagation Neural Network and Genetic Algorithm to the Preparation Processing of the Mg,Al-Hydrotalcite/Polymer Nanocomposite
Authors: Luo Qiang , Ren Qing Li
Published: March 2009

The three-layer structure back-propagation network model based on the non-linear relationship
between the break percentage elongation of the Mg,Al-hydrotalcite/PE nanocomposites and the
technological factors was established. And in order to accelerate the converging rate and avoid the local
minimum, dimensionality reduction and pre-whitening methods were used. Moreover, the optimum
technological process parameters were optimized with genetic algorithm. And the results show that using
both the back propagation neural networks and genetic algorithm is very efficient for the prediction of the
break percentage elongation of the Mg,Al-hydrotalcite/PE nanocomposite.
Preparation and Heat Treatment of High Purity Al(OH)3 and Sr(OH)2 Composite Powder
Authors: Hu Jin , Zhu Xiao Qin , Wang Kai Jun , Liu Jian Liang , Sun Jia Lin
Published: March 2009

The activated Al-Sr alloy powder hydrolyzed in pure water to prepare Al(OH)3 and Sr(OH)2
composite powder and had been treated at the temperature of 700°C. The structure, properties and heat
treatment of composite powder were investigated by XRD, SEM, BET, TG-DTG. The experimental
results showed that the hydrolysate of Al-Sr alloy powder is the composite powder of Al(OH)3 and
Sr(OH)2 by means of hydrolyzation reaction. The micrograph of the composite powder is piled up by
many sheet powders of 1-3μm. The specific surface area is great, up to 45.2 m2/g. The experimental
results also showed that, the crystalline water was dehydrated at 70-190°C and Sr(OH)2 and Al(OH)3
decomposed at 190-650°C. Their phase, micrograph and the surface area changed greatly after heat
treatment at the temperature of 700°C for 1 h.
Effects of Oxygen Content on the Properties of Ultra-High-Temperature Resistant Si-Al-C Fibers
Authors: Zhao Da Fang , Li Xiao Dong , Wang Hao , Zheng Chun Man , Wang Hai Zhe
Published: March 2009

Ultra-high-temperature resistant Si-Al-C fibers derived from polyaluminocarbosilane were
prepared by the procedures of melt-spinning, air curing and heated at 1800°C. It was found that oxygen
content in the cured fibers has great influences on the chemical composition of the Si-Al-C fibers and its
crystalline behavior during sintering. When oxygen content of cured fibers was too high, crystallite grains
in the fiber would grow up. Oxygen evolvement in the fiber during the preparation was studied in detail by
chemical analysis. It was found that oxygen is liberated mainly as CO gas from 1300°C to1600°C.
Low Temperature Sintering and Microwave Dielectric Properties of Zinc Titanate Ceramics for LTCC Applications
Authors: Liu Zong Chi , Zhou Dong Xiang , Gong Shu Ping
Published: March 2009

The effects of CuO-MoO3 addition on the sintering behavior and microwave dielectric properties of ZnO-TiO2 ceramics were investigated. ZnO-TiO2 ceramics were prepared with conventional solid-state method and sintered at temperatures from 850 to 1050 °C. The sintering temperature of ZnO-TiO2 ceramics with CuO-MoO3 addition could be effectively reduced to 950 °C due to the liquid phase effects resulting from the additives. A proper amount of CuO-MoO3 addition could effectively improve the densification and microwave dielectric properties of ZnO-TiO2 ceramics. ZnO-TiO2 ceramics with 3 wt% addition sintered at 950 °C for 4 h exhibited better microwave dielectric properties as follows: εr of 26.8, a Q×f value of 16780 GHz at 5.42 GHz, and a τ f value of +34.7 ppm/°C.
Ti/Al2O3 and Ni/Al2O3 Laminates Prepared by Plasma Activated Sintering (PAS)
Authors: Lin Jian Ping , Qiao Guan Jun , Jin Hai Yun , Guo Ya Jie , Lu Tian Jian
Published: March 2009

In this research, the metal and ceramic laminates Ti/Al2O3, Ni/Al2O3 were prepared by PAS.
The bonding interfaces of Ti/Al2O3, Ni/Al2O3 were observed and analyzed. The microstructures of
laminates were observed by SEM. It was shown that the joints of the samples were tight and had not
visible flaws. Moreover, the comparison of Ti/Al2O3 and Ni/Al2O3 laminates showed that the join
mechanisms of them were different. Ni/Al2O3 laminates that had not apparent conversion zone were
joined by diffusion and had lower bond strength. Ti/Al2O3 laminates have obvious conversion zone
because Ti and oxygen have strong combining power. Three-point bending test indicated that the fracture
of laminates was correlated to the bond strength of the interface.
Low-Temperature Combustion Synthesis and Characterization of Ce1-xPrxO2-δ Solid Solutions
Authors: Peng Cheng , Zhang Zhen , Huang Dong Lin , Liu Yan Li
Published: March 2009

Pr2O3-doped ceria nanopowders were synthesized by a nitrate-citrate combustion process. This
route is based on the gelling of nitrate solutions by the addition of citric acid and ammonium hydroxide,
followed by an intense combustion process due to an exothermic redox reaction between nitrate and
citrate ions. XRD analysis showed that no impurity were observed up to x=0.3 in Ce1-xPrxO2-δ systems.
The influence of ignition temperature on the characteristics of the powders was studied. The change of the
crystal structure with the content of doped Pr was investigated. The highest ionic conductivity,
σ600°C=2.45×10-3S/cm, was found for the composition of x=0.15.
Fabrication of Spark Plasma Sintering on Pb(Mg1/3Nb2/3)O3–PbTiO3 Ceramics Layers Prepared by Tape Casting and TGG Method
Authors: Zhou Shao Xin , Liu Dan , Zhou He Ping , Hu Zhong Bo , Hao Yong Mei
Published: March 2009

The spark plasma sintering technique was used to fabricate ceramics from Pb(Mg1/3Nb2/3)O3– PbTiO3 ceramic layers which were prepared by tape casting and TGG method used BaTiO3 templates as seeds. During heat treatment, epitaxial grain growth occurred on the BaTiO3 surfaces and formed <001> textured lead magnesium niobate-lead titanate, Pb(Mg1/3Nb2/3)O3-0.325PbTiO3 (PMN-32.5PT) ceramics. The phase compositions and microstructure were investigated. The results indicated that this method was an alternative sintering technology to synthesize dense lead-based relaxor ferroelectric ceramics.
Solution Combustion Synthesis of LiMn2O4 with Different Starting Reactant Compositions
Authors: Liu Gui Yang , Guo De Wei , Guo Jun Ming , Zhang Li Li , Chen Ke Xin
Published: March 2009

Spinel LiMn2O4 powders were prepared by solution combustion synthesis using nitrate and
acetate salts as raw materials and urea as fuel. The phase composition of as-synthesized powders was
identified by XRD and the microscopic structure was examined by SEM. Single-phase spinel LiMn2O4
was prepared when acetate salts were used, and the incorporation of nitrate salts resulted in the formation
of Mn2O3. The products consisted of slight agglomerations of fine particles with the size of 50-200nm. It
was found that the addition of nitrate salts increased the reaction rate and the yield of LiMn2O4 was
depressed when more nitrate salts were used as a reactant.
Effects of Fuel Content and Calcination Procedure on Phase Composition and Microstructure of LiMn2O4 Prepared by Solution Combustion Synthesis
Authors: Guo Jun Ming , Liu Gui Yang , Liu Jie , Guo De Wei , Chen Ke Xin , Zhou He Ping
Published: March 2009

Spinel LiMn2O4 was prepared by solution combustion synthesis. The effect of fuel content and
calcination procedure on phase composition and microscopic structure of LiMn2O4 was studied. X-ray
diffraction patterns showed that fuel content had no obvious influence on the grain size and phase purity
of LiMn2O4. Higher calcination temperature led to higher phase purity, lager grain size, and better
crystallization of resultant LiMn2O4. Below 600°C the effect of calcination time was inconspicuous,
which became notable above 700°C. Scanning electron microscope images showed that nanocrystalline
LiMn2O4 was obtained when the calcination temperature was lower than 600°C and the grain size
increased at higher temperatures.
Characterization of the Bismuth-Based Piezoelectric Ceramic System (1-x)Bi(Mg1/2Zr1/2)O3-xPbTiO3
Authors: Shabbir Ghulam , Qureshi A.H.
Published: March 2009

Dielectric properties and structural morphology of the Sc2O3 free and reduced lead content
piezoelectric ceramic system, (1-x)Bi(Mg1/2Zr1/2)O3-xPbTiO3 (BMZ-xPT), were investigated in this
study. The average grain size of the fresh fractured surfaces was of the order of ≤1 μm to ∼3 μm. The
dielectric constant, loss tangent, Curie temperature, remnant polarization, coercive field, piezoelectric
coefficient, and the planer coupling constant of ceramics in the vicinity of the morphotropic phase
boundary (MPB) (x∼0.55) were, ∼1450, 0.0952, ∼553 K, 29 (μC/cm2) , 23 (kV/cm), ∼185 pC/N, and
∼30%, respectively. It was observed that with decreasing PbTiO3 contents the phase transition anomaly
became broadened. The position of the dielectric constant maximum (ε′max) did not show any significant
variation with probe frequency, exhibiting character of diffuse phase transition like many other
disordered perovskites.
Photochromic Properties of WO3 Thin films
Authors: Wang Xin Min , Liu Bo , Cai Hong Hua , Luo Zhong Kuang , Ren Xiang Zhong , Liu Jian Hong , Zhang Pei Xin , Wang Fang
Published: March 2009

WO3 sol was prepared through the sol-gel process. Ethanol, acetone and SiO2 sol were added to the WO3 sol. The WO3 thin films on glass substrate were obtained with the hybrid sol by the dip-coating technique, and then were heat-treated at different temperatures for a certain time. X-ray diffractometer and scanning electron microscope were used to characterize the crystal structure and surface morphology of these coatings. Visible light transmittance changes of the thin films irradiated under UV light were measured with UV spectrometer. The experimental results demonstrated that photochromic effect, hardness and uniformity of thin films were improved when the thin films are obtained with the hybrid sol.
Preparation and Characterization of Transparent Nanocrystalline Ceramics
Authors: Lu Tie Cheng , Chang Xiang Hui , Zhang Jie , Qi Jian Qi , Luo Xiang Jie
Published: March 2009

The transparent nanocrystalline MgAl2O4 spinel ceramics were synthesized at lowtemperature
and high-pressure conditions with low-cost nano-sized MgAl2O4 powder. The sintering
characteristics of transparent nano-ceramics were investigated at 500~700oC under 2 ~ 5 GPa. The
optimal sintering condition for preparing transparent nano-ceramics was determined. The microstructure
and phase composition of powder, as well as the microstructures, morphologies, optical properties,
densities and mechanical properties of synthetic ceramics were investigated. The grain sizes of the
synthetic ceramics are less than 100 nm, far smaller than those of usual transparent micron-ceramics, and
the average grain size depends on the pressure and temperature. The transmittance at the saturation
plateau can near 80%. The relative densities of all samples are less than 99%, however, they are highly
transparent. The toughness, derived from energy dissipation, of the transparent nano-ceramics was
investigated and was compared with that of transparent micron-ceramic.
A New Method for the Preparation of Transparent AlON Ceramic
Authors: Zhou Ji Cheng , Liao Zhi Jun , Qi Jian Qi , Pang Wei , Wen Ya , Wen Jin Song , Wang Hai Ping , He Jun Feng , Wu Deng Xue , Lu Tie Cheng
Published: March 2009

Transparent AlON ceramics are prepared with single-phase AlON powder synthesized from
micron-sized aluminum and nano-sized alumina. The ceramics are prepared through sintering at the
temperature of 1880°C for 10, 20 and 40 hours in flowing-nitrogen atmosphere, respectively. The effects
of powder and temperature holding-time on transparent ceramic preparation and microstructure and
transparency are investigated. The results show that all samples are transparent and of a single-phase
AlON and, with increasing holding-time, the average pore size and porosity decreases and consequently,
the ceramics are dense and their transparency is improved.
Nanopowder and Fine-Grained Ceramics for Multilayer PTCR Elements
Authors: Zhao Jun , Gong Shu Ping , Cheng Chun Fang , Zheng Zhi Ping , Liu Huan , Zhou Dong Xiang
Published: March 2009

BaTiO3 nanopowders prepared by sol-gel process were used for multilayer PTCR ceramics in order to utilize grain boundary effect and lower sintering temperature. The precursor gel was calcined at different temperatures and the powders were characterized by XRD and TEM. The average grain size was about 26nm when calcined at 800°C for 2h. Effects of acceptor/donor concentration and sintering temperature on PTCR ceramics were also investigated. The optimal concentration of the donor was found to be 0.6mol with the acceptor concentration being 1/8 of the donor. Multilayer PTCR elements were fabricated by tape-casting technique. The jump ratio of PTCR chips sintered at 1240°C was above 103 with the average grain size smaller than 1~2 μm, which is suitable for the multilayer PTCR elements.
Influence of Rare Earth on the Electrical Properties and Microstructure of Barium Titanate Ceramics
Authors: Yang Wen Hu , Pu Yong Ping , Chen Shou Tian
Published: March 2009

The ceramic samples of BaTiO3+½xLn2O3+2mol%TiO2 (0.001≤x≤0.01) were prepared, where Ln is Y, Dy, Ho, Er or Y. The influence of rare earth on the resistivity and microstructure of the samples was investigated by the means of XRD, SEM and electric properties testing. The results showed that the resistivity of La-doped sample decreases when x= 0.003 compared with the undoped sample. However, the range of dopant concentration with Dy, Ho, Er or Y for semiconducting samples is wider, especially for Y-doping. Minimum resistivity at room temperature was observed when x=0.003, which is named after the critical concentration. The experimental results indicated that below the critical concentration of Dy, Ho, Er or Y, the substitution took place in the barium sublattice with electronic compensation, and the rare earth ions began to substitute for titanium gradually above the critical concentration. For Ho-doped BaTiO3 ceramic, the resistivity jump (PTCR effect) near the Curie temperature was the highest in the case of x=0.003. Fine-grained structure of the sample doped with 0.6mol% Dy led to the increase of breakdown field strength and dielectric constant of ceramic samples.
Properties of ZnO Varistors Prepared with Nano-Sized Powders
Authors: Luo Feng Chao , He Jin Liang , Lin Yuan Hua , Hu Jun
Published: March 2009

ZnO varistors with higher voltage gradients are expected in the power system, and the key to
this property is to diminish the grain size. In this paper, nano-sized ZnO particles are used as the raw
material in order to obtain small grains. Pellets are fabricated by two sintering methods: the conventional
pressureless sintering and the spark plasma sintering (SPS). For the samples fabricated by the
conventional sintering, the average grain size varies from 1 μm to more than 10 μm when the sintering
temperature changes from 900 oC to 1200 oC. The voltage gradient can reach as high as 2020 V/mm. The
grain size of the SPS samples is less than 1 μm, and the voltage gradients can reach 963 V/mm.
Influence of Different Calcination Conditions on the Microstructure and Phase Constitution of Nickel-Zinc Ferrite Nanocrystalline Powders Prepared by a Sol-Gel Auto-Combustion Method
Authors: Barati M.R. , Seyyed Ebrahimi S.A. , Badiei A.
Published: March 2009

In this work, nickel-zinc ferrite nanocrystalline powder has been prepared by a sol-gel autocombustion technique using nitrate-citrate gel obtained from metal nitrates and citric acid solution. Characterization of the nitrate-citrate gel, as-burnt powder and calcined powder at different calcination conditions were investigated by using XRD, FTIR and SEM techniques. The results revealed that the nitrate-citrate gel exhibits a self-propagating behavior after ignition and showed that the different calcination conditions affect the crystallite size of the synthesized powder as well as its phase constitution.
Synthesis, Characterization and Magnetism of Nanosized Copper Ferrite
Authors: Lv Wei Zhong , Luo Zhong Kuang , Liu Bo , Ren Xiang Zhong , Cai Hong Hua , Zhang Pei Xin , Liu Jian Hong
Published: March 2009

Copper ferrite powders were successfully synthesized by sonochemical method. The resultant powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR, differential thermal analysis-thermal gravimetric (DTA-TG), differential scanning calorimetry (DSC) and VSM. The particle saturation magnetization (Ms) is 66 emu/g and an intrinsic coercive force (iHc) is 2100 Oe when the precursor calcined at 950 °C for 15 h.
Low Temperature Synthesis of BiFO3 Film by Hydrothermal Method
Authors: Miao Hong Yan , Li Jia , Tan Guo Qiang
Published: March 2009

Polycrystalline BiFeO3 multiferroic films were fabricated on Ti substrates by hydrothermal
method from an aqueous Bi (NO3)3•5H2O, FeCl3•6H2O and NaOH solution. The films grow in alkaline
solution at low temperatures of 120°C-240°C for 18 hours. XRD analysis showed that well-developed
crystallines with single perovskite crystal phase were obtained. It was also found that the increase of
reaction temperature and concentration of NaOH were favorable for crystal growth and crystallographic
regularization. The microstructure, thickness and cross-section of the films were characterized by FE
SEM and EDS. Results indicated that dense and homogeneous BiFeO3 thin films could be obtained in an
appropriate hydrothermal condition.
Synthesis of CuFeO2 Powder by Sol-Gel Method
Authors: Wu Rui Fen , Pan Wei , Liu Shan , Li Jian
Published: March 2009

Sol-gel method has been adopted to synthesize CuFeO2 powder. Precursor solutions and heat
treatment conditions were studied using thermal analysis and XRD. Pure CuFeO2 was obtained using the
prepared sol-gel precursor that heat treated at 950°C for 5 h under nitrogen atmosphere.
Preparation and Structure Characterization of Mullite Fiber Porous Ceramic
Authors: Wang Hui , Zeng Ling Ke
Published: March 2009

Mullite fiber porous ceramic was prepared by forced liquid displacement forming and using
Mullite precursor sols as binders. SEM studies have shown that the uniformity of integral ceramic is good
although the binder and fiber congregate slightly. Mullite precursor sols spread to films or congregate
together in miniature. The mullite sol binders between fibers limit to the contact points and the redundant
binders form flat film even if they are superfluous, and the pores were not built up even where the binders
congregate badly. The results from mercury porosimetry testing of the mullite fiber porous ceramic
showed the relationship of cumulative intrusion and diameter for mullite fiber porous ceramic using
colloidal mullite binder, and the mean pore size is 45.6μm. The pore size distribution is very broad, from
about 0.2 to 174.9μm.
Synthesis of Ti3Si0.4Al0.8C1.8 Solid Solution
Authors: Li Cui Wei , Zhai Hong Xiang , Zhou Yang , Li Shi Bo , Zhang Zhi Li
Published: March 2009

In this study, free Ti/Si/Al/C powder mixtures with molar ratio of 3:0.4:0.8:1.8 were heated in Argon with various schedules, in order to reveal the possibility for the synthesis of Ti3Si0.4Al0.8C1.8 solid solution powder. X-ray diffraction (XRD) was used for the evaluation of phase identities of the powder after different treatments. Scanning electron microscopy (SEM) was used to observe the morphology of the Ti3Si0.4Al0.8C1.8 solid solution. XRD results showed that predominantly single phase samples of Ti3Si0.4Al0.8C1.8 was prepared after heating at 1400oC for 5 min in Argon and the lattice parameters of Ti3Si0.4Al0.8C1.8 lay between those of Ti3SiC2 and Ti3AlC2.
Evolution of Nanoindentation Hardness of Fe/Cu Nanometer-Scale Multilayers by Magnetron Sputtering
Authors: Gao J. , Wu Z.L. , Zhang Z.P. , Cao B.S. , Lei M.K.
Published: March 2009

Fe/Cu nanometer-scale multilayers with nominal modulation wavelengths ranging from 5
to 40 nm are deposited by direct current magnetron sputtering on Si (100) substrates. Modulation
structures of the multilayers are examined by small angle / wide angle x-ray diffraction (SA/WAXRD)
and cross-sectional transmission electron microscopy (XTEM). Hardness of the multilayers is
measured by using nanoindentation. All the multilayers have Fe (110) and Cu (111) textures. Interface
coherency is observed in the multilayers with designed modulation wavelengths of 5 and 10 nm. The
hardness increases firstly and then deceases with increasing the modulation wavelength, and reaches
peak value of 7.29±0.29 GPa in the multilayers with nominal modulation wavelength of 10 nm. The
evolution of the hardness of the mulitlayers is explained by interface width and modulus difference
between sublayers.
Deposition of CrN Coatings by Filtered Cathodic Vacuum Arc
Authors: Mo Ji Liang , Zhu Min Hao , An J. , Sun H. , Leng Yong Xiang , Huang Nan
Published: March 2009

CrN coatings were deposited on cemented carbide substrates by filtered cathodic vacuum
arc technique (FCVA). The effect of different deposition parameters: nitrogen partial pressure,
substrate-bias voltage and preheating of the substrate, on the structural and mechanical properties of
the coating was investigated. X-ray diffraction analysis was used to determine the structure and
composition of the coatings. The tribological behaviour and wear properties of the coatings against
Si3N4 ball at different normal loads were studied under reciprocating sliding condition. The results
showed that a smooth and dense CrN coating with good properties can be obtained provided a pure Cr
interlayer was pre-deposited. The optimal deposition parameters were the nitrogen partial pressure of
0.1 Pa, substrate-bias voltage of -100 V. Preheating of the substrate was no good for improving the
properties of the coating. The FCVA CrN coating showed high hardness and good wear resistance,
which was probably attributed to its smooth surface and dense microstructure. The wear mechanism
of the CrN coating was a combination of abrasion and oxidation. However, the coating flaked off at
high normal load due to the deficient adhesion strength of the coating to the substrate.
Fabrication Of Nd:YVO4 Thin Film Waveguide Grown on Si/SiO2 by Pulsed Laser Deposition
Authors: Li Hong Xia , Song Ren Guo , Wu Xin , Wang Ji Yang
Published: March 2009

High quality Nd:YVO4 thin films were fabricated successfully by using a pulsed laser
deposition technique. The properties of the samples were characterized by using X-ray diffraction,
atomic force microscopy, and prism-coupling measurements. According to above discussion, we
concluded the optimal preparation conditions for Nd:YVO4 films prepared on Si/SiO2 substrates.
Rf Sputtering of Composite Fluorocarbon/ZnO Films and their Basic Properties
Authors: Zhang Yu Hui , Ji Quan , Wang Xue
Published: March 2009

Composite fluorocarbon/ZnO films were deposited by R.F. sputtering using
polytetrafluoroethylene (PTFE) and Zn target on polyethylene terephthalate (PET) substrate. Argon
was used as the working gas and oxygen as reacting gas. The obtained films were characterized by
AFM, UV-visible spectrophotometer, XPS and static contact angle measurements. The composite
films are islands-structure composed of nanometer particles. Surface of the islands is not flat. The
static contact angle of water is larger than 90°, possessing excellent hydrophobicity. The composite
films exhibit multi-enhanced ultraviolet absorption due to π-π-conjugated molecular structure,
surface morphology and nano-sized ZnO absorbing effect.
Effects of Incident Angle on Microstructure of Ni-Cr Film Deposited by PVD
Authors: Shan Ying Chun , Xu Jiu Jun , He Xiao Dong , Li Ming Wei
Published: March 2009

A 2D kinetic Monte Carlo (KMC) simulation has been applied to study the microstructure
of Ni-Cr film deposited by physical vapor deposition (PVD) for variable incident angle. In the KMC
method, two phenomena were incorporated: adatom-surface collision and adatom diffusion, the
interaction between atoms was described by embedded atom method and jumping energy was
calculated by molecular statics calculations, initial location of adatom was located by Momentum
Scheme. The results reveal that there exists critical incident angle, which is 35˚ for Ni-Cr thin film.
When incident angle is less than 35˚, incident angle have less affect on surface roughness factor and
packing density, compact films with smooth surface are obtained, their surface roughness factor is
bellow 1.12 and packing density is more than 99.6%. However, when incident angle is more than 35˚,
surface roughness factor increases quickly and packing density decreases sharply with incident angle
increasing: surface roughness factor increase to 1.5 and 2.3 for incident angle of 45˚ and 60˚
respectively, packing density is below 99% and 96% accordingly. Which reveal that the
self-shadowing effect emphasizes with incident angle increasing when the incident angle is more than
35˚.
Microstructure and Formation Mechanism of Aluminized Coatings on Nickel-Based Superalloys
Authors: Pei Ji Bin , Zhang Liwen , Niu Jing , Zhang Quan Zhong
Published: March 2009

Aluminized coatings prepared on nickel-based superalloys can provide good protection
against high temperature oxidation and hot corrosion. This study investigated the simple aluminized
and silicon-aluminized coatings on nickel-based superalloy K4104. The simple aluminized coating
was prepared by pack cementation and the Al-Si coating was prepared by slurry aluminizing,
respectively. The microstructure of simple aluminized and Al-Si coatings was analyzed by means of
scanning electron microscope (SEM), X-ray diffraction (XRD) and electron probe microanalysis
(EPMA). And the formation mechanism of simple aluminized and Al-Si coatings was discussed. The
results showed that the simple aluminized coating was about 49 um thick and consisted of three
layers. The outer layer mainly consisted of Al-rich β-NiAl. The intermediate layer consisted of Ni-rich
β-NiAl and Cr-rich. The inner diffusion layer consisted of Cr-rich and γ’-Ni3Al. The microstructure of
Al-Si coating showed that the coating was about 70 um thick and consisted of five layers. The Al-Si
coating consisted of CrxSiy, Al-rich β-NiAl, Ni-rich β-NiAl, Cr-rich and γ’-Ni3Al. The microstructure
of simple aluminized coating was compared with that of Al-Si coating in order to find out the effect of
Si. Owing to the effect of Si, there was a Transition layer in Al-Si coating. The Al-Si coating was
thicker than simple aluminized coating. The declining trend of the aluminum concentration in the
Al-Si coating was smoother than that of the simple aluminized coating.
Study on Electroless Ni-P Deposit on W-Cu Alloy and its Anti-Corrosion Mechanism
Authors: Hao Long , Zhang Ye Ming , Yang Chao , Zhu Hua , Mao Xu Hui , Lin An , Gan Fu Xing
Published: March 2009

With suitable pretreatment, a compact and even nickel-phosphorus alloy coating was
obtained on W-Cu alloy by electroless deposition from solutions containing nickel sulphate as a
source of nickel and sodium hypophosphite as the reducing agent and a source of phosphorus. The
Ni-P coating was normally prepared from acidic baths at high temperature of the order of 90oC with
the pH of 4.8 and it was smooth and uniform and exhibited high crystal refinement and high
microhardness and superior corrosion resistance. The microhardness, adhesion and corrosion
resistance mechanism of Ni-P deposit were studied. The microhardness of the Ni-P alloy deposit
increases greatly by tempering at various temperatures. The Ni-P deposit has a strong adhesive force
with W-Cu alloy substrate checked by thermal shock test and scribe test. The anti-corrosion ability of
Ni-P coating and its anti-corrosion mechanism were measured using immersion experiment and
potentiodynamic polarization techniques. The results showed that the corrosion resistance of Ni-P
coating was higher than that of W-Cu alloy substrate in the 10vol.% sulfuric acid, monitoring sweat
solution and 3.5wt.% sodium chloride solution. The anti-corrosion mechanism of electroless Ni-P
coating immersed in 3.5wt.% sodium chloride solution was studied using potentiodynamic
polarization techniques. The surface micromorphological morphology and structure of the Ni-P
coating were investigated using Scanning Electronic Microscope (SEM) and X-ray Diffraction
(XRD). The results indicated that the Ni-P alloy coating consisted of microcrystals and it was
amorphous in structure, and the electrochemical measurement showed passive film formed on Ni-P
coating during immersion test in the 3.5wt.% sodium chloride solution.
Research of Microstructure and Properties of the 4Cr14Ni14W2Mo Steel with QPQ Salt-Bath Nitriding
Authors: Xiong Guang Yao , He Bo Lin , Zou Rui
Published: March 2009

The wear-resistance, corrosion resistance, hardness can be greatly increased by using low
temperature QPQ complex salt-bath treatment. And it is a new strengthening method without
distortion in the treating process. The surface of 4Cr14Ni14W2Mo steel was treated using this
method. The microstructure and depth of the treated surface for the steel were analyzed using SEM.
The sliding wear resistance was tested on the M-2000 tester and the micro-hardness was tested using
401MVA microscopy hardness tester. The corrosion resistance was tested in the 5%NaCl water by
using spraying method. The experimental results indicate that a certain depth of white layer and
diffusion layer of the steel can be obtained by using low temperature QPQ complex salt-bath
treatment. The nitriding compound layer with high hardness, superior wear resistance and stable
microstructure, can also be obtained on the surface of the parts. The highest hardness in the surface is
HV0.11012. The surface hardness is 2.8 times higher than that of inner part. The depth of white layer is
from 10 to 12μm. The experimental results and applied results show that the low temperature QPQ
complex salt-bath treatment has many advantages, such as fast nitriding speed, uniform heating, short
process time, low treating temperature, small distortion, high production rate, low cost, stable
nitriding quality no pollution and so on.
The Study on the Dispersants and Structures of Ni-P-α-Al2O3 Composite Electroless Plating Coating
Authors: Feng Li Ming , Liu Ke Gao , Guo X.F.
Published: March 2009

Dispersants are selected and optimized by determining the height of emulsion in the
colorimetric cylinder after standing in order to ensure the homogeneity of the powder and the stability
of electroless plating solution. Experimental results show that non-ionic surfactants such as
PEG6000,PEG10000,OP-10 have stronger emulsifying ability to α-Al2O3 powder in ordinary
condition and IW has more stability at 80~90°C. The optimum conditions are suggested as PEG6000
8g, IW 0.95g and ethanol 3mL per 50mL solution. Moreover, this composite electrolessplating
solution is stable for seven days under 90°C. Therefore it has more dispersing ability. The SEM
images show that the powder in the coating is homogeneous. The electroless plating coating consists
of α-Al2O3 and amorphous Ni-P that will change into crystal Ni3P and Ni-base solid solution after
heat treatment at 400°C for one hour, the α-Al2O3 powders are dispersed evenly in the nickel matrix.
Controlled Plasma Nitriding for an Optimum Balance between PACVD TiBN Coating Scratch Resistance and Substrate Toughness
Authors: He Y. , Apachitei I. , Zhou Jie , Walstock Twan , Duszczyk J.
Published: March 2009

The plasma nitriding (PN) process in the duplex surface treatment was controlled to create
nitrided diffusion layers with depths of 0, 5, 15 and 80 m in the substrate of the DIN 1.2367 hot-work
tool steel with the maximum microhardness values of 600, 700, 820 and 1000 HV, respectively. The
scratch properties, i.e. the critical loads of cohesion (LC1), adhesion (LC2), breakthrough (LC3) and
worn out (LC4), of the PACVD TiBN coating (boride, 5-7 at.%) on these substrates increased linearly
with the maximum hardness of the PN diffusion layer. Instead of the composite hardness, the peak
scratch hardness was used to describe the load-carrying capacity of the TiBN coating and PN substrate.
Deep tensile cracks in the PN substrate with a hardness value of 1000 HV formed during the scratch
test at a load as low as 90 N, indicating the low fracture toughness of the substrate. Therefore, an
optimum balance between the scratch properties of the coating and the good fracture toughness of the
nitrided substrate must be achieved through exercising the control of the PN and PACVD duplex
process.