bluuebunny/crossref_metadata_2025 huggingface dataset:
Superplastic Forming of Silicon Nitride at Low Temperature
Authors: Luo Jun Ting , Zhang Kai Feng , Wang Guo Feng , Chen Guo Qing
Published: March 2009

Si3N4 ceramic bodies were prepared by liquid phase sintering (LPS) with the amorphous nano-sized Si3N4 powders. Nano-sized Al2O3 and Y2O3 powders were introduced as additives. XRD analysis showed that the sintered body consists of β-Si3N4 and Si2N2O which confirms that phase change temperature of β-Si3N4 is
lower than traditional Si3N4. SEM examination showed that the grain size of sintered body is smaller than 300 nm. Superplastic forming can be undertaken at the low temperature of 1550°C in a nitrogen atmosphere when the forming velocity is less than 0.5 mm/min. The formed parts rupture when the forming velocity is 1 mm/min
or the forming temperature is 1500°C. Only a few defects are observed in the blank before forming, but many cavity groups are present in the formed workpiece.
Investigation on Superposition Rule and Influence of Multi-Thermal-Source Temperature Field on SiC Synthesizing
Authors: Wang Xiao Gang , Yang Bin , Shao Shuiyuan
Published: March 2009

ANSYS software was used to simulate the superposition rule of multi-thermal-source temperature field. The SiC productions synthesized by multi-thermal-source furnace were examined through X-ray diffractometer (XRD) and energy depressive spectroscopy (EDS). The crystalline and density were determined by scanning electron microscopy (SEM). The superposition rule and influence of multithermal-
source temperature field on SiC synthesizing were clarified.
Formation Mechanism of Interior Microflaws in the Preparation of Polymer-Derived Silicon Carbide Fibers
Authors: Chu Zeng Yong , Cheng Hai Feng , Wang J. , Song Yong Cai , Wang Yan Dong , Feng C.X.
Published: March 2009

Microflaws were detected on the cross-section of polymer-derived silicon carbide fibers and their formation mechanism was studied by varying the curing degree and the firing rate. The results show that microflaws decrease in size with increase of the curing degree due to an increased ceramic residue. The results also show that microflaws decrease in size with decrease of the firing rate. No microflaws are
detectable when the firing rate is as low as 10K/h. This indicates that the microflaws are the main channels of evolution gases and the pressure of these gases leads to their formation and propagation. So a high curing degree and a low firing rate are both preferred in the preparation of dense silicon carbide fibers.
Influence of Dy Doping on Microstructure of PLZT Ceramics
Authors: Zhang Yong , Ding Ai Li , He Xi Yun , Cao Zi Ping , Yin Qing Rui
Published: March 2009

Polycrystalline dysprosium (Dy) doped PLZT ceramics with compositional formula [Pb0.88 (La1-xDyx)0.12](Zr0.40 Ti0.60)O3] were prepared by hot-pressed solid-state method. Dy3+ concentration x varied from 0 to 0.5. All samples present single phase with tetragonal structure and the tetragonality was
increased with increasing Dy3+ content. The Raman spectra indicated that Dy3+ ions could be distributed in both A and B site of ABO3 perovskite structure depending on the doping amounts.
Fabrication and Mechanical Properties of HAp/Ti3SiC2 (60 vol.%) Composite by Sparkle Plasma Sintering
Authors: Shi Sui Lin , Pan Wei , Fang Ming Hao , Fang Zhen Yi
Published: March 2009

HAp-Ti3SiC2 (60 vol.%) composite was fabricated using Sparkle Plasma Sintering (SPS). The mechanical properties and microstructure of the composite sintered at different temperature were investigated. The results show that no reaction occurred between HAp and Ti3SiC2, and the strength and fracture toughness of the composite were improved relative to pure HAp, which may be attributed to the change of microstructure and fracture mode as an effect of Ti3SiC2 addition.
Thermodynamics and Kinetic Considerations behind the Growth of AlN Whiskers Synthesized by Carbothermal Reduction
Authors: Fu Ren Li , Zhou He Ping , Chen Ke Xin , Ferreira José Maria F.
Published: March 2009

AlN whiskers have been successfully synthesized by carbothermal reduction. The
thermodynamics and growth kinetics of AlN whiskers were studied at 1600°C using CaCO3 as a catalyst. The research indicated that AlN whiskers are more easily nucleated from the liquid phase than at the surface of solid phase. AlN whiskers are nucleated by VLS mechanism and the liquid, which plays a dominant role in the VLS mechanism, is formed by Al-Ca interphases, such as CaO×2Al2O3 and CaO×6Al2O3. Kinetic studies suggest that the catalyst reacts with Al2O3 to form a
low melting point eutectic (1390°C). The liquid phase formed at this low melting point eutectic provides good conditions for nucleation of AlN whiskers. At the synthesis temperature, the liquid phase vaporizes, thus creating suitable conditions for the subsequent growing of whiskers by the VLS mechanism. This growing mechanism conforms to thermodynamics and a lot of proof indicates that
screw dislocations play an important role in the process of the whiskers' formation.
Electroless Plating of Ni-P-CNTs Composite Coating
Authors: Zhao Guo Gang , Deng Fu Ming
Published: March 2009

Ni-P-CNTs composite coating were deposited by electroless plating. The factors which influenced the content of carbon nanotubes in deposits, such as the types of agitation, surfactants and carbon nanotubes concentration in the plating bath, were examined. The surface morphology, structure and properties, such as microhardness, wear resistance and friction coefficient of the -CNTs coating, were
investigated. The results showed that the Ni-P-CNTs composite coating greatly increased the hardness and wear resistance and decreased the coefficient of friction with the increase of the content of carbon nanotubes in deposits, and the introduced carbon nanotubes did not change the structure of the Ni-P marix
of the composite coating.
The Fracture Toughness and DBTT of MoB Particle-Reinforced MoSi2 Composites
Authors: Xiong Zhi , Wang Gang , Jiang Wan
Published: March 2009

The room temperature fracture toughness and the high temperature DBTT of MoB
particle-reinforced MoSi2 composites were investigated using Vickers indentation technique and MSP testing method， respectively. Modified Small Punch (MSP) test is a method for evaluation of mechanical properties using very small specimens, and it’s appropriate for the determination of strength and DBTT. It was found that the approximate fracture toughness of the composite is 1.3 times that of monolithic MoSi2, and its DBTT is 100°C higher than that of monolithic MoSi2 materials. Cracks deflection is a probable mechanism responsible for this behavior.
The Thermal Stability of Mo(Al,Si)2 Phase
Authors: Zhang Xiao Li , Yang Jian Feng , Lu Zhen Lin , Jin Zhi Hao
Published: March 2009

It has been reported that formation of Mo(Al,Si)2 phases by the addition of aluminum can improve the mechanical and oxidation properties of MoSi2, however, the constancy of the Mo(Al,Si)2 phase was not explored. In this study, MoSi2 preforms were added with Al whose contents were 1, 5, 10wt%, respectively, and these performs were sintered at 1150°C-1550°C, respectively. These MoSi2
specimens with the Al addition were heat-treated at 1350°C-1550°C in N2 atmosphere. Results showed that single Mo(Al,Si)2 phase existed only when the aluminum content was above 5 wt%. It was difficult to form single Mo(Al,Si)2 phase for the samples with 1wt% Al addition. For the samples with 5wt% Al, only
the single Mo(Al,Si)2 phase was formed at 1350°C; and a large number of the tetragonal MoSi2 were re-appeared at 1450°C, 1550°C. For the samples with 10wt% Al addition, the single Mo(Al,Si)2 phase would always formed at individual sintering temperatures. The formation temperature of the single Mo(Al,Si)2 phase was decreased with increment of aluminum content. For the samples composed of the single Mo(Al,Si)2 phase, the Mo(Al,Si)2 phase disappeared gradually and was substituted for MoSi2 and a little of other phases, such as Mo3Al4Si2, by heat treatment at temperatures mentioned above for 40 min. This indicated that the Mo(Al,Si)2 phase was unstable at the temperatures above 1350°C.
Preparation of Al-Based Metal Matrix Composites Reinforced by Cu Coated SiC Particles
Authors: Wang Hai Long , Zhang Rui , Xu Hong Liang , Lu Hong Xia , Guan Shaokang
Published: March 2009

In order to improve the interfacial behavior between SiC and Al, a surface layer of Cu was coated on SiC particles. The influence of pH value on the coating process was analyzed. A powder metallurgy method was used to prepare the Al-based metal matrix composites (MMCs). SEM, XRD techniques were used to characterize the sintered compacts. It was found that the optimized pH value during the coating process was 1~2. The specimen showed the maximum density when sintered at
750oC. Inter-metallic compound of Al3.21Si0.47 was detected which contributed to the enhancement at the interface between SiC and Al. The hardness of the composites is improved to 90 MPa.
Novel Low Thermal Conductivity Ceramic Materials for Thermal Barrier Coatings
Authors: Pan Wei , Xu Qiang , Qi Long Hao , Wang Jing Dong , Miao He Zhuo , Mori Kazutaka , Torigoe Taiji
Published: March 2009

The increase of the efficiency for gas turbines leads to the increasing combustion-chambertemperatures. Rapid degradation of the conventional yttria-stabilized zirconia coatings does not fulfill therequirements at these temperatures for a reliable thermal barrier coatings (TBCs) due to the phasetransformation of zirconia and the sintering behaviour. Therefore, it is very important to develop novelceramic materials for TBCs with low thermal conductivity and long-term stability at high temperatures.In this paper, the developments of potential novel ceramic materials for TBCs with low thermalconductivity are reviewed.
Formation of Bone-Like Apatite of Bioceramics Modified by Cold Plasma in SBF and Mechanism of Active Modification
Authors: Su Bao Hui , Ran Jun Guo , Gou Li , Wang Fang Hu , Guo Hai Su
Published: March 2009

BGC, HA, β-TCP and biphase calcium phosphate (β-TCP/HA) were modified by using the cold plasma technique in the present study. The study results came from the formation of bone-like apatite in SBF and results of osteoblast culture in vitro, SEM, XPS, and XRD. The results showed that the formation of bone-like apatite on bioceramics modified by cold plasma was easier than that of no modification and the growth of osteoblast could be promoted. The active mechanism was that impact
on bioceramics by means of the particles with high energy and high activity led to rough and etched surface of bioceramics, as well as the distortion of bioceramics crystal, which increased solubility of materials and local concentration of Ca and P ion. It was helpful for the formation of bone-like apatite. It was showed that the modification using cold plasma technique could increase the activity of
bioceramics.
Crystallization and Mechanical Properties of Spodumene-Diopside Glass Ceramics
Authors: Hu An Min , Liang Kai Ming , Zhou Feng , Peng Fei , Wang Guoliang
Published: March 2009

The mechanical properties of spodumene-diopside glasses ceramics with 4-12% TiO2 were investigated. The main crystalline phases precipitated were eucryptite, β-spodumene and diopside. As TiO2 content increasing, the morphology of glass ceramics transformed from coarse to fine microstructure, then to reverse. The flexural strength, elastic moduli, Vickers hardness and fracture toughness of the glass-ceramics were measured. The flexural strength of glass–ceramics containing
9%TiO2 was 198MPa, the Young’s modulus and fracture toughness were 91.3GPa and 2.3 MPa·m1/2 respectively. It was indicated that the mechanical properties were correlated with crystallization and morphology of glass ceramics
Indentation Size Effect in the Nanohardness of Soda-Lime Glass
Authors: Li Zong Huai , Gong Jiang Hong , Peng Zhi Jian , Miao He Zhuo
Published: March 2009

The nanoindentation load-displacement curves of soda-lime glass were analyzed with the widely adopted Oliver-Pharr method. The resultant nanohardness exhibits a significant indentation size effect (ISE). An empirical relationship between the peak load and the contact depth, which was established to analyze the ISE in microhardness tests, was suggested to be suitable for describing the
load-dependence of the nanohardness. By comparing the best-fit values of the parameters included in this empirical relationship, the origin of the load-dependence of nanohardness was analyzed briefly.
Ferroelectric Properties of Bismuth Titanate Ceramics by Sm3+/V5+ Substitution
Authors: Chen M. , Liu Zu Li , Yao Kai Lun
Published: March 2009

The ferroelectricity of Bi3.2Sm0.8Ti3O12 (BST) and Bi3.2Sm0.8Ti2.97V0.03O12 (BSTV)ceramics prepared at 1100oC by a conventional ceramic technique is investigated. These ceramics possess random-oriented polycrystalline structure. The remanent polarization (Pr) and coercive field (Ec) of the BST ceramics are 16 µC/cm2 and 62kV/cm, respectively. Furthermore, V5+ substitution
improves the Pr value of the BST ceramics up to 25µC/cm2, which is larger than that of the BST ceramics. Therefore, the co-substitution of Sm3+ and V5+ in Bi4Ti3O12 (BIT) ceramics is effective for the improvement of its ferroelectricity.
Dry Friction and Wear Properties of Aluminum Matrix Composites Reinforced with 3D Network Ceramics
Authors: Yao Jun Ping , Wang Wei , Chen Leping , Chen Bing Kun , Zhang Lei
Published: March 2009

A new 3D network ceramics (skeleton) reinforced aluminum alloy composites was
designed and fabricated. Dry friction and wear behaviors of the new composites were investigated. The friction coefficients and wear rates of the matrix and the composites were measured at various temperatures and loads. The worn surfaces of the samples were examined with a scanning electron microscope, and the effect of the 3D network ceramics on the wear mechanisms was discussed accordingly. The composites had much better wear resistance than the matrix. The improvement in the wear resistance of the composites became more prominent at higher ceramics volume fraction, higher temperature, and larger normal load. Moreover, the friction coefficients of the composites remained stable with increasing normal load, especially at elevated temperature. It is suggested that the 3D network ceramics support the load applied onto the sliding surface, which not only restricts the
plastic deformation and high temperature softening of the alloy, but also protects the oxide film(Al2O3) on the surface.
Study on the Cemfiber Reinforced High-Performance Concrete
Authors: Xing Feng , Leng Fa Guang , Li Wei Wen
Published: March 2009

The effects of Cemfiber on the workability, mechanical properties, resistance to chemical corrosion and drying shrinkage of High-Performance Concrete (HPC) have been studied systematically. The results show that: (1) the effects of Cemfiber on the workability of HPC are related to parameter of mix proportion. Generally speaking, Cemfiber does not reduce the workability of HPC; (2) the effect of Cemfiber on the compressive strength and flexural strength is very small; (3) the HPC incorporated with Cemfiber has high resistance to corrosion of hydrochloric acid; (4) Cemfiber may reduce drying shrinkage of HPC significantly; (5) Cemfiber may increase cracking resistance of HPC resulting from drying shrinkage.
Unified Model for Fracture of Brittle Solids
Authors: Krstić Vladimir D.
Published: March 2009

A unified model for fracture of brittle solid based on crack opening displacement is presented. The model allows the prediction of elastic and fracture response of brittle materials containing spherical and cylindrical pores and polycrystalline solids containing anisotropic residual stresses. The analysis can also be used to predict spontaneous cracking and fracture of two phase systems possessing mismatch
stresses.
Wettability of SiC/Ag Plus Ti System
Authors: Li Shu Jie , Liu Hong Li , Zhang Jian Jun
Published: March 2009

Wettability of ceramics by liquid metals is of importance for joining of ceramics to metals and manufacturing of cermets. Wettability of reaction bonded SiC /Ag plus Ti system was studied. The contact angle was determined by high temperature photography. The microstructure and composition of the interfacial region were analyzed. For SiC/pure Ag system, the contact angle at 998°C in vacuum is 128.4º. The wettability of the system is remarkably improved by adding Ti into the metallic filler. Also, the contact angle of the system is strongly affected by the wetting temperature and the dwelling time. The results indicate that interfacial reactions take place during the test, and the reactions facilitate the wetting. Microstructural study reveals that inter-diffusion takes place and a reaction layer forms at the interface.
Probabilistic Modeling for Composites with Particle Interface Degrading
Authors: Chang Hua Jian , Zhou Yu , Nakagaki Michihiko
Published: March 2009

A popular type is of metal matrix reinforced by ceramics particles. It has been revealed that the composites are susceptible to interfacial degrading, which may be dramatically detrimental to the overall properties of composites. In present paper, an equivalent inclusion type constitutive model was developed for the composites with dispersed particles on which imperfections of the material interface are incurred.
Two fundamental tensors are derived, the modified Eshelby tensor and the damage tensor of the weakened particles. By applying these tensors into a carefully schemed constitutive law, the effects of interfacial degrading on the overall properties of composite materials can be investigated. The interface degrading includes sliding and debonding. The numerical results show that even with the nil resistible sliding coefficient, its effect on the overall Young’s modulus is not notable unless the volume fraction of the particle is so high as more than 70%. For the global Poisson’s ratio, when there is the sliding on the interface, the Poisson’s ration rises irrespective of the constituent material values. It is noted that even in
the elastic state, the global Poisson’s ratio rises greater than that of both the constituents. This phenomenon might indicate that even at the elastic state, the particle interfacial sliding would give somewhat a plasticity-like deformation behavior. The effect of the interfacial debonding on the overall properties of the composite is more conspicuous in comparisons of the sliding. The debonding parameter greatly affects both the properties for almost entire range of the particle volume fraction. Unlike the sliding effect case, the debonding decreases Poisson’s ratio at all cases, which represents the micro-damage effect occurring in the composite.
Design, Processing and Evaluation of Graded Piezoelectric Ceramic Bending Actuators
Authors: Li Jing Feng , Zhang Hai Long , Takagi Kenta , Watanabe Ryuzo
Published: March 2009

This paper introduces the development of two kinds of graded piezoceramic bending actuators. For designing the graded compositional profiles, classical lamination theory (CLT) is used to explore the optimal gradient that generates large electromechanical response. As the first model material, a laminated
piezoceramic bimorph actuator was designed and fabricated with a graded compositional distribution of PZT and Pt, and its electric-induced bending characteristics were evaluated and compared with the analytical results by CLT. Furthermore, porosity-graded PZT ceramics were developed, which may be
used as the preforms for the infiltration process to fabricate bending actuators with graded ceramic/metal and/or ceramic/polymer interfaces. The fabrication process and property evaluation of homogenously porous and porosity-graded PZT ceramics were introduced.
Processing and Properties of PSZN-PZT Quaternary Piezoelectric Ceramics
Authors: Wang Li Feng , Sun Qingchi
Published: March 2009

Piezoelectric Pb(Sn1/3Nb2/3)O3-Pb(Zn1/3Nb2/3)O3-PbTiO3-PbZrO3 (PSZN-PZT) quarternary ceramics with varying Zr/Ti ratio, which locate in the vicinity of the morphotropic phase boundary (MPB), were prepared by the conventional calcination route. The conventional and twice synthesis methods were compared. XRD patterns indicated the more complete perovskite phase was
formed by the twice synthesis methods. The sintering behavior was investigated. The microstructure was studied and the piezoelectric and ferroelectric properties and the properties under high electric field were determined. The optimized results were obtained when the ratio of Zr/Ti is 43/45 and the sintering temperature is 1260°C.
Dielectric and Piezoelectric Properties of Praseodymium Modified Lead Zirconate Titanate Ceramics
Authors: Zhou Hua , Sun Qingchi , Lu Cuimin
Published: March 2009

Praseodymium (Pr) modified lead zirconate titanate ceramics (Pb1-1.5xPrx (ZryTi1-y) O3 with x = 0.02, 0.04, 0.06, 0.08 and y = 0.51, 0.52, 0.54, 0.56, 0.58, 0.60) were prepared by the high temperature solid-state reaction method. X-ray diffraction (XRD) results show that the morphotropic phase boundary
(MPB) of Pb0.955Pr0.03(ZryTi1-y)O3 (PPZT1) is located in the area where the molar fraction of Zr is near 55%, when the molar fraction of Zr is 54% and the sintering temperature is 1240°C with 1h curing time, the superior piezoelectric properties of compositions of PPZT1 system were optimized, a set of d33 = 420
pC/N; eT 33/e0 = 2,000; Tc = 314°C; Qm = 76; tand = 2% and kp = 0.53. On the other hand, Pb1-1.5xPrx(Zr0.54Ti0.46)O3 (PPZT2) is far from MPB and their compositions are all in tetragonal phase.
New Lead-Free Ferroelectric Materials for High-Temperature Applications: Nb-Doped Bi3.5Nd0.5Ti3 O12
Authors: Cao Zi Ping , Ding Ai Li , He Xi Yun , Zhang Y. , Zeng X.
Published: March 2009

Bi3.5Nd0.5Ti3O12 (BNT) ferroelectrics modified with different concentrations of Nb are prepared by a hot-pressing method. XRD diffraction shows that all samples have only a layeredstructured pervoskite phase. Raman spectra confirm that the crystal symmetry change locally when increasing Nb concentration. It is found that the introduction of a suitable amount of Nb can enhance the remnant polarization of BNT. The temperature dependence of dielectric constant is also investigated in BNT ceramics. All samples have high Curie temperature above 530°C.
Dielectric and Piezoelectric Properties of Na0.42K0.08Bi0.5 TiO3 and Na0.45K0.05Bi0.5TiO3 Ceramics
Authors: Zhao Su Chuan , Zhang Lina , Li Guo Rong , Zheng Liao Ying , Ding Ai Li
Published: March 2009

Na0.42K0.08Bi0.5TiO3 and Na0.45K0.05Bi0.5TiO3 ceramics were fabricated by the solid-state reaction. The structures were determined by X-ray diffraction. Dielectric, ferroelectric and piezoelectric properties of the ceramics were measured and discussed. The ceramics have a single perovskite phase with rhombohedral symmetry at room temperature. The thermal variations of the permittivity follow the law 1/ e − 1/ em = C(T − Tm)2 which is the character of typical relax
ferroelectrics, when temperature is higher than the temperature of the maximum of dielectric constant (Tm). The depolarization temperature (Td) of spontaneous polarization is 215oC for Na0.45K0.05Bi0.5TiO3 and 152oC for Na0.42K0.08Bi0.5TiO3 respectively. There exist two different dielectric behaviors of the Na0.42K0.08Bi0.5TiO3 ceramic, without and after poling. Na0.45K0.05Bi0.5TiO3
possesses relatively high kt and Td. The use for device application has been indicated.
Microwave Dielectric Characteristics of BaO-Nd2O3-TiO2 Nano-Particles by Millimeter-Wave Sintering
Authors: Xiang Yong , Xie Dao Hua , Zhao Yu Shuang , Su Yi Long , Luo Ji Run
Published: March 2009

By means of 34.5 GHz millimeter-wave (MMW) sintering, BaO-Nd2O3-TiO2 microwave ceramic dielectric was prepared from nano-particles of the xBaO×(0.35-x)Nd2O3×0.65TiO2 ternary compound, which possess fine grain, low porosity and good dielectric characteristics. The materials which have ultra-low dielectric loss can be fired by MMW heating at very high frequency, which is unable to be done by normal microwave heating at 2.45 GHz. The sintering temperature is 160 ~ 400°C lower than that of normal firing. The ceramic sample consists of the main phase of Nd2Ti2O7 with perovskite-like layer structure (PLS) and the secondary phase of BaNd2Ti4O12 (Ba4.5Nd9Ti18O54)with perovskite-like tungsten bronze structure, being the same as the results from normal sintering. The excellent microwave characteristics were observed.
Effect of Iron Oxide on the Structure, Electrical and Magnetic Properties of (70% mole V2O5- (15-x)% mole P2O5-15% mole B2O3) Semi Conducting Glass System
Authors: Assem E.E.
Published: March 2009

A glass system according to the molar formula (70% mole V2O5- (15-x)% mole P2O5-15% mole B2O3), where x = 0, 1, 2.5, 5 and 7.5 % mole Fe2O3, was prepared by melting the pure powder chemicals at porcelain crucibles at 1000Co for three hours until the homogenous glass was obtained. The samples were quenched in air and heat-treated at 500 Co for 1, 2 and 3 h. The density, the molar volume,
the electrical conductivity and magnetic properties were measured before and after the heat-treatment. The crystalline phases due to heat-treatment were determined using x-ray diffraction. The heat-treatment causes change of BO3 to BO4 and forming non-bridging oxygen. Replacing the phosphorus oxide with the iron oxide increases the magnetic properties while the conductivity increase up to 5% mole and then decreases. The changes of electrical and magnetic properties with heat-treatment time have a random behavior due to the change of the structure if the samples with heat treatment.
Effect of BaCO3 and Pb3O4 on Properties of BaTiO3-Based PTCR Ceramics
Authors: Ma Wei Bing , Qu Yuan Fang , Hao Yan Xia
Published: March 2009

High-performance PTCR ceramics with low resistivity (8Ω.cm) at room temperature and around four orders magnitude of the PTCR jump were obtained by adding BaCO3 and Pb3O4(B-P) in BaTiO3. The influence of adding B-P on the sintering behavior, the microstructure and the electrical properties of BaTiO3-based PTCR was investigated. The phase constituent in the sintered ceramics was
analyzed by XRD and it was shown that the metallic layered Ba3Pb2O7 phase was synthesized during the sintering. Analysis suggested that making the weak reduction atmosphere at the grain boundary may decrease the grain-boundary resistivity.
Ceramic Technologies for Anode-Supported Solid Oxide Fuel Cells
Authors: Tancret Franck , Schleich Donald M.
Published: March 2009

One of the most promising technologies for future applications of solide oxide fuel cells (SOFC)is the so-called “anode-supported” configuration: a dense yttria-stabilised zirconia (YSZ) ceramic electrolyte is deposited as a thin film over a porous Ni / YSZ cermet substrate anode, followed by a porous ceramic cathode such as La1-xSrxMnO3 (LSM). In this paper, a short review is made of the current technologies available to achieve this particular architecture, and to optimise the service behaviour. Then, alternative materials and fabrication technologies, as well as their possible impact on performance, are proposed and investigated.
Study of YSZ Amperometric Oxygen Sensor with a Dense Barrier Layer
Authors: Shi Xing , Zhang Yue
Published: March 2009

A new type of amperometric oxygen sensor was developed by an approach of co-pressing and co-sintering YSZ solid electrolyte. A dense LSM+YSZ composite electrode which was used as both cathode and diffusion barrier. Pre-sintered composite and YSZ powders were dry-pressed together to form a sheet with dual-layer of LSM+YSZ/YSZ. The sheet was then sintered at 1450°C. The anode was
made of Pt paste, which was printed on to the other side of YSZ. The experiment results showed that the oxygen sensor exhibited a quite low operating temperature. At 400°C, the limiting current appeared in the voltage from 0.7 to 1.2V and the limiting current was a good linear relationship with the oxygen concentration up to 10 %. The sensor has some excellent features such as a rapid response, no reference
gas, simple configuration and low cost. Taken together with the chemical stability of the diffusion barrier, the sensor is suitable for the control of air-to-fuel ratio in lean-burn internal combustion engines.
Weak Ferromagnetism and Magnetoresistance in Sm1/3 Sr2/3 FeO2.95
Authors: Zhao Y.M. , Quan H.J.
Published: March 2009

The temperature dependence of the magnetization (ac and dc) indicate that
Sm1/3Sr2/3FeO3-d undergoes an antiferromagnetic transition at TN = 150 K. In low applied fields, the zero field cooled (ZFC) and field cooled (FC) magnetization below TN exhibit a hysteretic behavior. This behavior is suppressed by high applied field. The ac susceptibility for Sm1/3Sr2/3FeO2.95 shows that there is a clear frequency dependence developing below TN. The relusts of both ac and dc
measurements suggest that the antiferromagnetic long-range order coexist with ferromagnetic correlations. Field-dependent resistivity versus temperature measurements reveal the existence of a magnetoresistance (MR) in the temperature below TN. The appearance of some ferromagnetic component within an antiferromagnetically ordered state may be responsible for the MR at low
temperature.
Preparation and Structure of Ba2Ti9O20 and BaTi4O9 Ceramics Derived from Sol-Gel Powders
Authors: Lu Sheng Guo , Chen Haydn , Mak C.L. , Wong K.H. , Chan H.W.L. , Choy C.L.
Published: March 2009

Ba2Ti9O20 (B2T9) and BaTi4O9 (BT4) ceramics have been fabricated using sol-gel technique. The sol-gel derived powder was produced from barium acetate and butyl titanate using acetic acid as solvent. The as-prepared powders were then calcined at different temperatures ranging from 600° to 1200°C. After that, the powder was pressed into pellets and further sintered at different temperatures ranging from 1250°C to 1380°C. XRD characterization and Raman spectroscopy showed that after calcining the sol-gel powder at 900°C for 2 h and sintering the pressed pellets at 1330°C for 4 h, triclinic B2T9 and orthorhombic BT4 ceramics could be obtained. The dielectric constant and Q-value are 35 and 1910 at 6.1 GHz.
Coating Nano-TiO2 on Optical Fiber with Al(H2PO4)3 Adhesive
Authors: Zhao Yu Hong , Liu Jia Chen , Li Shun , Liu Yi Rong
Published: March 2009

To meet the need of optical fiber photoreactor designed by mechanism of TiO2 photocatalysis, nanometer TiO2 was coated on the surface of optical fiber by dipping nude fibers into an Al(H2PO4)3-contained TiO2 slurry. Effects of slurry conditions, including content of TiO2 and addition of Al(H2PO4)3 adhesive, on coating thickness and quality were determined. Coating process, especially the effect of coating times, was also concerned. Based on the experimental results, fitting slurry conditions and process parameters were suggested for obtaining high-quality TiO2 coating on optical fiber surface.
Improved Artificial BP Neural Networks and Genetic Algorithm Used to Predict the Purity of the Artificial Synthetic Hydrotalcite
Authors: Luo Qiang , Ren Qing Li
Published: March 2009

A prediction model for purity of the artificial synthetic hydrotalcite under varied process parameters based on improved artificial back-propagation (BP) neural networks is developed. And the non-linear relationship between the hydrotalcite purity and the raw material adding amount of NaOH, MgCl2 and AlCl3 was established based on BP learning algorithm analysis and convergence improvement.
The hydrotalcite purity can be predicted by means of the trained neural net. Thus, by virtue of the prediction model, the future hydrotalcite purity can be evaluated under random complicated raw material amounts. Moreover, the best processing technology is optimized using the genetic algorithm.
Preparation of Ni-Co Spinel Oxide by Alloy Oxidation Method
Authors: Chi Bo , Yang Xiao Zhan , Li Jian Bao , Wang Ning
Published: March 2009

In this paper, NiCo2O4 spinel oxide was synthesized by the oxidation of Ni-Co alloy. The variables that affect the formation of spinel oxide include the Ni-Co ratio in the alloy, the oxidation temperature and time. 350°C is the upper oxidation temperature limit. And longer oxidation time is helpful. Surface roughness analysis shows that with the formation of NiCo2O4, the surface shows rougher.
Study of the Technology of Chemical Copper Plating on Al-CuO Agglomerated Powders
Authors: Yan Jun , Yi Jian Zheng , Cui Hai Ping , Du Xin Kang , Wang Jian Jiang
Published: March 2009

This research focus on the technology of copper chemical plating on Al-CuO agglomerated powders with the size of 150-200µm. Orthogonal design is employed to gain the optimized formula, and the quality of the cladding was analyzed by means of SEM and EPMA. The results show that the cladding is uniform and the Al-CuO powders are primarily coated by copper.
Preparation of PLZT Powders from Oxides via High-Energy Ball Milling Process
Authors: Peng Qing Song , Jiang Wan , Li Jing Feng
Published: March 2009

Lanthanum-modified lead zirconate-titanate (PLZT5/54/46) powders were prepared from the commercial PbO, La2O3, TiO2 and ZrO2 powders by high-energy ball milling process. The synthesized powders milled for different hours were characterized using XRD and SEM. Thedesigned PLZT perovskite phase was formed from the mixture of the starting materials after milling for 20 hours. PLZT(5/54/46) ceramics were obtained using the produced powders milled for 20 h
followed by sintering at temperatures ranging from 1000 to1200°C. Ferroelectric property of the PLZT ceramics was also measured.
Synthesis of Nanometer Cobalt Oxide (Co3O4) Powders by Solid-State Reaction under Microwave Irradiation
Authors: Li Xiu Yan , Zeng Ling Ke , Liu Pi Nan
Published: March 2009

Nanometer cobalt oxide powders were obtained by decomposition of precursors CoC2O4×2H2O at 350°C for 3h. The precursors were synthesized by solid-state reaction with H2C2O4×2H2O and CoCO3 under microwave irradiation. The products were characterized by XRD and TEM. The results showed that the nanometer Co3O4 is cubic and the mean particle is 19 nm with narrow distribution and weak agglomeration.
Synthesis and Characterization of BaCe0.8Y0.2O2.9 Nanopowder by Sol-Gel Auto-Ignited Method
Authors: Ma Jing Tao , Lin Xu Ping , Zhang Bao Qing , Wang Jiu Lin
Published: March 2009

A sol-gel auto-ignited synthesis, which is a hybrid of sol-gel and auto-ignited techniques, was applied to preparation of homogeneous and stoichiometric BaCe0.8Y0.2O2.9 nanocrystalline ceramic powder as solid electrolyte used in solid oxide fuel cells at 1000°C. Optimal pH value for the mixed citrate-nitrate solutions was determined by calculation. The DTA-TG and XRD were used to investigate
the thermal decomposition of the gel precursor. The structure and phase present of the nanocrystalline BaCe0.8Y0.2O2.9 powders were characterized by XRD, BET and SEM techniques.
Synthesis and Characterization of LiNixCoyMn1-x-yO2 as a Cathode Material for Lithium Ion Batteries
Authors: Liao Pei Yun , Duh Jenq Gong
Published: March 2009

The newly developed LiNi0.6Co0.4-xMnxO2 (0.1 < x < 0.3) cathode materials were synthesized by calcining the mixture of NixCoyMn1-x-y(OH)2 and Li2CO3 at 900-940 oC for 15 hr in flowing O2 atmosphere. The NixCoyMn1-x-y(OH)2 precursor was obtained by the chemical co-precipitation method at the pH value controlled by the concentration of NaOH, NH4OH and transition metal sulfate solution. The X-ray diffraction patterns indicated the pure layered hexagonal structure LiNi0.6Co0.4-xMnxO2. The electrochemical behavior of LiNixCoyMn1-x-yO2 powder was examined by using test cells cycled within the voltage range 3-4.3 V at the 0.1C rate for the first cycle and then at the 0.2C rate afterwards. LiNixCoyMn1-x-yO2 cathode materials showed good initial discharge capacity (165-180 mAh/g) and cycling performance. The fading rate was less than 5 % after 20 cycling test. It is demonstrated that LiNixCoyMn1-x-yO2 electrode should exhibit great potential for the future application in lithium-ion battery cathode material.
Storage Stability of Ceramic Slurries for Gelcasting
Authors: Dai Chun Lei , Yang Jin Long , Huang Yong
Published: March 2009

In the industrialization of gelcasting, storage of ceramic slurry has been one of the key problems that must be solved. Except for sedimentation of ceramics particle, solidification properties of slurries were also affected after long-term storage. In this article, some factors in the process of slurry were discussed, and corresponding solution methods were put forward.
Viscoelastic Properties of Pb(ZrTi)O3-Based Slurry for Tape Casting
Authors: Jiang Xiang Ping , Chen Yu Quan , Chan Helen L.H. , Yin Qing Rui
Published: March 2009

PZT-based slurry with Newtonian behavior was prepared for tape casting. The viscoelasti cproperties of the slurry were studied. High quality of green tape and well sintered of PZT-based thick films are obtained using the PZT-based slurry with Newtonian behavior.
Preparation of (111)-Oriented Pt Electrode Films with Quasi-Monocrystal Properties on MgO/TiN Buffered Si(100) by PLD
Authors: Chen Tong Lai , Li Xiao Min
Published: March 2009

Atomic-scale smooth Pt electrode films have been deposited on MgO/TiN buffered Si (100) by the pulsed laser deposition (PLD) technique. The whole growth process of the multilayer films was monitored by using in-situ reflection high energy electron diffraction (RHEED) apparatus. The Pt/MgO/TiN/Si(100)
stacked structure was also characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The HREED observations show that the growth mode of the Pt electrode film is 2D layer-by-layer growth. It is found that the (111)-oriented Pt electrode film has a
crystallinity comparable to that of monocrystals. The achievement of the quasi-single-crystal Pt electrode film with an atomic-scale smooth surface is ascribed to the improved crystalline quality of the MgO film.
On the Microstructure and Electrical Properties of Undoped and Antimony- Doped Tin Oxide Thin Film Deposited by Sol-Gel Process
Authors: Du Gang , Zhang Dao Li , Zhao Lan , Xu Jian Mei , Zhou Dong Xiang
Published: March 2009

Undoped and antimony-doped tin oxide (ATO) thin films were prepared by sol-gel process in the solution of metal salts of tin (II) chloride dehydrate and antimony tri-chloride. The microstructure of the thin films was analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). Compared with undoped tin oxide, doped antimony tin oxide films coated glass substrate were homogeneous in composition and morphology after being sintered at different temperatures. Electrical behavior of the doped films was discussed in terms of sheet resistance measured by four point probe. From the experimental data, the sheet resistance of the films could be as low as 100-200Ω/□
Preparation and Electrical Properties of (100) Preferred (Ba,Sr)TiO3 Bilayer Thin Films Derived from Pulse Laser Deposition Method
Authors: Lu Sheng Guo , Friddle Philip A. , Xu Z.K. , Siu G.G. , Chen Haydn , Wong K.H. , Mak C.L.
Published: March 2009

Bilayer Ba0.6Sr0.4TiO3 - Ba0.4Sr0.6TiO3 and Ba0.4Sr0.6TiO3 - Ba0.6Sr0.4TiO3 thin films were deposited on the LaNiO3-buffered Pt/Ti/SiO2/Si substrates using pulse laser deposition method. A (100)preferred orientation was obtained. The structure was characterized using x-ray diffraction (XRD) and Raman spectroscopy. The leakage current, and dielectric permittivity versus temperature were characterized. Results indicated that the (100) preferred bilayer structure had less leakage current and smaller loss tangent, which was in favor of enhancing the quality of thin film used as microwave
dielectrics.
Effects of Seeding on Large Crystal Growth of NaX Zeolite by Continuous Crystallisation
Authors: Kim Ik Jin , Lee Hae Jin , Tsiakaras Panagiotis
Published: March 2009

The problem with zeolite crystals synthesized by conventional method is that they are extremely small of two to eight microns, To better define the structure of zeolite, scientist need to grow crystal that are 100 to 1000 times larger. In this work, Large crystal zeolite X of uniform crystal size of 50µm were grown by a continuous crystallization method from seed crystals (5-10µm) in a mother solution having a composition 3.5Na2O : Al2O3 : 2.1SiO2 : 1000H2O. In order to grow crystals of zeolite X to an appropriate size by the continuous method, the mother solution was supplied into the starting solution with various seed content (3~20wt%) in an autoclave at 90°C after 7 days, 12days, 16days, 19days and 24 days, respectively.
Electromechanical Coupling Characteristics of SMA Wires under the Constraints of Stress and Strain
Authors: Yan Shao Ze , Xu Feng , Liu Xia Jie , Wang Jin Hui
Published: March 2009

AC and DC conductivities have been measured by using the real (e¢) and imaginary (e¢¢) parts of the dielectric constant data of glass and glass-ceramics (GC) at different temperatures in the rage 297-642K and in the frequency range 100 Hz to 10 MHz. Using Anderson –Stuart model, we have calculated the activation energy, which is observed to be lower than that of the DC conductivity.
The analysis for glass/glass-ceramics indicates that the conductivity variation with frequency exhibits an initial linear region followed by nonlinear region with a maximum in the high-frequency region. The observed frequency dependence of ionic conductivity has been analyzed within the extended Anderson–Stuart model considering both the electrostatic and elastic strain terms. In glass/glassceramic
the calculations based on the Anderson-Stuart model agree with the experimental observations in the low frequency region but at higher frequencies there is departure from measured data.
Dependence of Dielectric Behaviour of Magnesium Aluminum Silicate Glass-Ceramics on Alumina Content
Authors: Kothiyal Govind P. , Goswami Madhumita , Mishra R. , Sharma B.I. , Yakhmi J.V.
Published: March 2009

Magnesium aluminum silicate glass-ceramics were prepared by controlled heat treatment of base glass. The Al2O3 content was varied from 7.58 to 14.71mol % keeping total Mg content almost constant in the form of (MgO+MgF2). The crystalline phases were identified by X-ray diffraction technique while scanning electron microscopy was employed for finding the microstructure in the sample. The dielectric behaviour of the material was studied over the frequency range from 10-107 Hz and in the temperature range from 603 to 793K using impedance analyzer. X- ray diffraction studies revealed the formation of pure and mixed phases of MgSiO3, fluorophlogopite and Mg2SiO4 depending upon the alumina content. Mixed phase material has higher dielectric constant (e′), loss factor (e²) and dissipation
factor (tand) than the single-phase material at lower frequencies. Dielectric constant (e′) decreases with frequency rather sharply up to 104Hz, and then remains nearly constant at higher frequencies up to 107Hz. However, tand first increases and then decreases with frequency passing through a broad peak. In all the cases e¢ and tan d are seen to increase with temperature. The activation energies for dipolar relaxation were calculated for all samples and were found to vary from1.77Joule/mole to 13.82Joule/mole with variation of alumina from 7.58 to 14.71mol %.
Effect of Dopants on the Corrosion Behaviour of Zirconia by Steel at High Temperature
Authors: Guo Yan Ling , Long Shi Gang , Telle Rainer
Published: March 2009

Zirconia based material is one of the most interesting materials for semi-solid processing of steel because of its good mechanical properties and high corrosion resistance at high temperatures. In many cases, degradation of zirconia refractories or advanced ceramics is due to unexpected tetragonal-tomonoclinic^transformation accompanied by volume expansion. But only little attention was paid to outdiffusion of stabilising additives. In present paper, zirconia based ceramics with different rare-earth oxides (Y2O3 and CeO2) are used in contact with HS6-5-2 steel at 1330°C in order to obtain a good understanding about the corrosion behaviour of high-strength zirconia tool material, especially the effect of yttria and ceria on the corrosion behaviour of zirconia. The results showed that both Y2O3 and CeO2
diffused out of the zirconia structure and formed new compounds with alloying elements of steel at the zirconia grain boundaries. Both lack of stabiliser and grain growth result in t-m transformation and cracks were formed in zirconia ceramic.
Nanostructured Diamond Coated CoCrMo Alloys for Use in Biomedical Implants
Authors: Lawson T.R. , Catledge S.A. , Vohra Yogesh K.
Published: March 2009

A wide variety of materials are currently under consideration for use in biomedical
implants. Within the scope of certain implants is the need to withstand extensive wear created by repeated use and pressure on high stress joints. Substantial research is directed toward metal-onmetal technology and cobalt chrome molybdenum (CoCrMo) is a prime candidate given its longevity [1]. Wear-resistant surface coatings for the standard CoCrMo biomedical alloy may be a
simple and effective way to extend implant lifetime. In this study, we show that an initial plasma nitriding step for CoCrMo alloy is beneficial for attaining adhesion of a nanostructured diamond coating subsequently grown by microwave plasma chemical vapor deposition (CVD). The initial plasma nitriding step is quickly and easily performed in the CVD reactor and results in the formation of chromium nitride phases (CrN, Cr2N) as well as a phase transformation of cobalt from
hexagonal to face centered cubic. We suggest that the success in terms of achieving adhesion of the diamond coating to the CoCrMo alloy involves chromium nitride phases acting as a diffusion barrier to carbon, thus preventing direct reaction of carbon with cobalt and the extensive graphitization that would follow.
A New Injectable Bone Substitute Concept (MBCP Gel TM): First Clinical Results in Human Maxillo-Facial Surgery
Authors: Weiss Pierre , Clergeau Léon Philippe , Enckel Bénédicte , Amouriq Yves , Giumelli Bernard , Jean Alain , Daculsi Guy
Published: March 2009

For the first time, an injectable bone substitute (IBS) made of a suspension of Calcium phosphate ceramic was used in a clinical trial in human after extraction of non conservable tooth (36 or 46). 11 patients did agree for implantation of their sockets with the biomaterial. It was an explorative study and the results showed no pain due to the biomaterial implantation, no infection, no inflammation and perfect biocompatibility. The safety and the bioactivity of this concept of biomaterial were confirmed in human implantation after several animals’ pre-clinical studies.
Improvement of Porosity of a Calcium Phosphate Cement by Incorporation of Biodegradable Polymer Microspheres
Authors: Khairoun I. , Billon A. , Daculsi Guy , Merle Christian , Bouler Jean Michel
Published: March 2009

In this study a biodegradable polymer microspheres were used to make an alpha-TCP calcium phosphate bone cement macroporous. The biodegradable polymer microspheres were synthesised at the laboratory and a sieve fraction of this microspheres ranging between 100 and 300 microns was incorporated in a calcium phosphate cement, where the powder contained a-Ca3(PO4)2 (a-TCP). The microspheres content of the cement was 10 %. The cement pastes were prepared at liquid-to-powder ratios from 0.32 to 0.40 ml/g. X-ray diffraction and Infra-red spectroscopy was performed to analyse the reaction on powdered samples that were let to set at different times in a Ringer’s solution at body temperature. Mercury porosimetry has been used at the main method for porosity measurements. Scanning electron microscopy (SEM) was performed on fractured samples
fro microstructural analysis. The microspheres seemed to retard slightly the cement setting and to reduce progressively the compressive strength after aging in aqueous solutions which were continuously refreshed. SEM pictures and XRD patterns of the samples after 1 and 4 weeks of aging showed that the microspheres
were dissolved progressively. Mercury porosimetry measurements assessed at different times of aging showed an improvement in the total porosity and the pore diameter of the set material and confirmed SEM and XRD results.