bluuebunny/crossref_metadata_2025 huggingface dataset:
Fracture Mechanics Analysis of Ground Fissure
Authors: Fan W. , Yu M.H. , Oda Yasuji , Lin Yu Li , Chen Li Wen , Iwatate Takahiro
Published: March 2009

The ground fissure is one of primary geological disasters in Xi’an, China. The extension pattern and deformation failure area near fissure are studied through the FEM of elastic-plastic fracture mechanics in this paper. The results show the crack extension is not completely tension crack, it is mixed mode when the confined aquifer was pumped. The extents of earth surface deformation and stress concentration of beyond plate are larger than that of the bottom one. It is consistent with observational results.
Influence of Surface Films on the Susceptibility of Inconel 600 to Stress Corrosion Cracking
Authors: Mintz Todd S. , Devine Thomas M.
Published: March 2009

The susceptibility of Inconel 600 to stress corrosion cracking (SCC) in the primary water of a pressurized water reactor (PWR) is strongly dependent on potential. In the present paper we assess the validity of the hypothesis that the potential dependency of SCC is related to the influence of potential on the identities of the surface films that form on Inconel 600. That is, according to the hypothesis,
SCC requires the presence of a particular surface film.
The identities of the surface films that develop at different potentials on Inconel 600 in PWR primary water (2 ppm LiOH + 1200 ppm H3BO3) at 288°C were investigated in situ by surface enhanced Raman spectroscopy (SERS).
To help identify the components of the films that grow on Inconel 600, the films that form on unalloyed nickel, chromium, and iron in 288°C PWR primary water were also investigated.
The main results of the in situ SERS investigation of the surface films are as follows. (1) No films were formed on Inconel 600 at potentials below the region of potential in which SCC occurs. (2) A chromium-rich M3O4 oxide forms on Inconel 600 in the SCC region. (3) NiO forms as the potential is increased immediately above the region of SCC susceptibility. (4) At still higher potentials, films of (Fe,Cr)2O3 and Ni3-xFexO4 form.
The results are consistent with concept that specific films affect SCC susceptibility.
Mechanism of Hydrogen Embrittlement Due to the Interaction of a Crack, Moving Dislocations and Hydrogen Cluster
Authors: Taketomi S. , Yokobori Jr. A.Toshimitsu , Shoji Tetsuo
Published: March 2009

Previously, we proposed stress corrosion cracking model on the basis of interaction of dislocation and hydrogen around a crack tip to predict discontinuous cleavage-like fracture during stress corrosion cracking (SCC) for ductile fcc alloys. Furthermore, we conducted numerical analyses using this proposed model. In the analysis, hydrogen was treated as a static cluster. However, actually, both of hydrogen and dislocations move with interaction each other. Therefore, in this paper, a physical model of dislocation and hydrogen dynamics with interaction was proposed. And the behavior of interaction between dynamic dislocations and hydrogen was investigated. On the basis of this analysis, the discontinuous cleavage-like fracture during SCC for ductile fcc alloys was clarified.
A Fast Shape Inversion Method of Flaws in Materials for Infrastructures
Authors: Kitahara M. , Onishi M. , Nakahata Kouichi , Yamada Masayoshi
Published: March 2009

The Born inverse scattering method is applied to the shape reconstruction of flaws in the concrete
materials. To accelerate the inversion process, the algorithm of the fast Fourier transform is introduced
in the integration process of the scattering amplitude. The concrete specimens with flaw models are
prepared and the scattered waveforms from flaws are acquired in the pulse-echo mode. The shape of
flaws is reconstructed by using the measured waveforms and the performance of the inversion method
is demonstrated experimentally.
Strength of Liquid-Phase-Sintering Cordierite Ceramics
Authors: Liang Hui , Yang Hai Bo , Xie Zhi Yong , Xu Ting Xian , Xu Ming Xia
Published: March 2009

The high dense pure cordierite ceramics and liquid-phase-sintering cordierite ceramics were prepared with the starting powder made by sol-gel progress. The porosities of them are less than 6.21%, and some can be up to 1.0% especially. The flexural strength of the sample can get to 167 MPa, which is greater than that of 103 MPa of pure cordierite ceramics. The composition, fracture behavior
and microstructure of the liquid-phase-sintering cordierite ceramics are investigated. The result shows that the increased flexural strength is mainly attributed to the change in cell parameters of cordierite and the small grain size.
Colloidal In-Situ Consolidation Forming of Al2O3 Ceramics Using Modified Starch
Authors: Chen Ling , Song Xian Liang , Ye Jian Dong , Li Bing
Published: March 2009

The forming of Al2O3 ceramics was carried out by the colloidal in-situ consolidation using modified starch in this work. The effects of the modified starch content in the alumina suspensions on their rheological behavior, consolidation, microstructure and properties of the green bodies were investigated. The different shape and high relative density of ceramic green bodies were achieved by this method. The results indicated that the alumina suspensions with modified starch were easier to cast due to their low viscosity and high fluidity. After drying, the linear shrinkage of the green bodies was low, ranging between about 1.5% and 2.2% and their bulk density was higher than 57% of the theoretical density. The maximum bending strength of the dried green bodies reached to 8.2 MPa and the microstructure of the green bodies was uniform with a narrow unimodal distribution of pore size. It is concluded that the colloidal in-situ consolidation casting using modified starch can perform near-net shaping of ceramic components with high-performance and it is a potential forming
technique for ceramics.
Microstructure and Mechanical Properties of Al2O3/ZrO2 Composites Prepared by Gelcasting
Authors: Jiao Bao Xiang , Qiu Tai , Li Chun Cheng , Shen Chun Ying
Published: March 2009

Microstructure and mechanical properties of zirconia-toughened alumina (ZTA) composite ceramics prepared by gelcasting process were investigated. The results indicated that Al2O3-ZrO2 composites have high bending strength and fracture toughness for the solid loading of the suspension ³ 50vol.%. The bending strength and fracture toughness of sintered ZTA ceramics reach values as high as
631.5 MPa and 7.64 MPa·m1/2, respectively, with solid loading of suspension being 55vol.%. The t-ZrO2 content is increased, and the uniformity of ZrO2 particle distribution is improved in sintered samples prepared by gelcasting compared with those by dry pressing.
Cordierite-CeO2 Composite Ceramic: A Novel Catalytic Support Material for Purification of Vehicle Exhausts
Authors: Shi Z.M.
Published: March 2009

Stable oxygen concentration in exhausts is a decisive factor in catalytic purification of the vehicle exhausts. Nanostructured CeO2 is generally added into catalytic coating on a ceramic support to adjust the oxygen concentration because it possesses a unique oxygen storage capacity (OSC). However, a small amount of CeO2 gets insufficient when the oxygen concentration fluctuates in a
large range. In the present work, the cordierite-CeO2 composite ceramic with oxygen storage capacity was prepared for a support material of catalytic converters. The oxygen storage-release performance of the ceramics, including temperature of releasing oxygen, adsorption process of oxygen and the oxygen storage, was examined by a temperature-programmed gas chromatography. The composition of the ceramics was analyzed by an X-ray powder diffraction (XRD) and a scanning electron microscope (SEM) to validate the reliability of the ceramic as the support material with OSC. Results show that the ceramics consist of α-cordierite and CeO2 phases, the latter of which is uniformly dispersed throughout the cordierite matrix. The ceramic powder with 10-20wt% of CeO2 possesses the expected oxygen storage capacity. It is suggested that this novel cordierite-CeO2 composite ceramic is helpful of improving the purification effect of vehicle exhausts.
Wear of Twist Drills in ZrO2/CePO4 Composite Machining
Authors: Ma L.J. , Yu Ai Bing , Tan Yan Fei
Published: March 2009

Machinable ZrO2/CePO4 composite was fabricated. ZrO2/CePO4 and mild steel materials were machined with tungsten-cobalt carbide twist drills. The material removal characteristic was analyzed by consideration of tool wear in different stock removals. Wear of twist drills was observed with SEM. Wear widths on major flank were measured with microscope. The experimental results show when ZrO2/CePO4 was drilled, wear widths on flank were much bigger comparing to mild steel drilling processes. The wear of twist drills occurred on major flank, minor flank and on chisel edge. Wear on minor flank is a unique characteristic in drilling of ZrO2/CePO4 ceramics. There exist obvious scratch remarks on tool wear. The tool wear results from abrasive wear, adhesive wear and oxidation wear.
In Situ Reaction Synthesis of Porous Silica-Matrix Ceramics
Authors: Ding Shu Qiang , Jiang Dong Liang , Zhu Su Min
Published: March 2009

A novel technique was developed to synthesize porous silica–matrix ceramics from silicon carbide and alumina with an Y2O3 addition, using pine sawdust as a pore former. The porous ceramics were fabricated at temperatures of 1300–1500 oC in air by a reaction–bonding process based on two reactions: (1)SiC+2O2→SiO2+CO2 (Oxidation) and (2)2SiO2+3Al2O3→3Al2O3·2SiO2 (Mullitization). Reaction–bonding behavior, mechanical property and open porosity were investigated as a function of Y2O3 content as well as sintering temperature and holding time. Moreover, phase composition and microstructure of the porous silica–matrix ceramics were studied by X–ray diffraction (XRD) and scanning electron microscopy (SEM).
Polycrystalline Silicon Thin Films on SiC Substrates for Solar Cells
Authors: Li Hai Feng , Huang Yong , Wan Zhi Jian , Zhang Hou Xing , Zhang Li Ming , Xu Y. , Li Xiao Dong
Published: March 2009

The thin-film of silicon deposited by RTCVD on pressureless sintered SiC substrate with the size of 30mm×20mm, which is cleaned by ultrasonic method and chemical treatment. The crystal size of silicon columnar grain can reach 190 µm and its preferred orientation is [111] after ZMR process.
Solar Cells from Thin Silicon Layers on AlN
Authors: Wan Zhi Jian , Huang Yong , Zhang Hou Xing , Li Hai Feng
Published: March 2009

Polycrystalline silicon layers were grown on AlN ceramic substrates in a rapid thermal chemical vapor deposition system at high temperature (~1150°C). Larger columnar grains, > 5µm in size, were obtained by the zone melting recrystallization (ZMR) technique. The p-n junction is formed by a phosphorous diffusion process to make a solar cell. Solar cell devices based on this Si layer result possess
an open-circuit voltage of about 0.17V and a short-circuit current of about 6.6mA/cm2.
Growth and Characterization of High Quality MgO Thin Films by Ultrasonic Spray Pyrolysis
Authors: Bian Ji Ming , Li Xiao Min , Gao Xiang Dong , Yu Wei Dong
Published: March 2009

Ultrasonic spray pyrolysis has been applied to deposit MgO thin films on Si(100) and quartz glass substrate. The microstructures and properties of the as-grown MgO thin films were examined by X-ray diffraction, scanning electron microscopy, spectrophotometer and semiconductor resistivity meter. The results indicates that the MgO thin films deposited under optimal conditions shows smooth and dense surface without visible pores or defects over the substrate, and as well as
good thickness uniformity. Almost completely (100)-oriented MgO films with the transmission higher than 90% in UV/VIS region and the resistivity at least in the order of 107Ω-cm were obtained. MgO thin film with such a crystal quality seems to be very suitable for acting as a buffer layer for the subsequent epitaxial growth of films.
Improving the Strength of Al2TiO5 by Adding Spodumene
Authors: Pan Ji Yong , Gong Jiang Hong
Published: March 2009

Aluminium titanate (Al2TiO5) is an excellent oxide ceramic material with a very low
thermal expand coefficient. Aiming at improving the bending strength Al2TiO5, spodumene was used as additives for preparing Al2TiO5 and the effect of adding spodumene on the mechanical properties of Al2TiO5 was investigated in this paper. It was found that adding spodumene, instead of simple oxides, may significantly enhance the bending strength of Al2TiO5.
Structure of the Coatings onto Ceramic Cutting Tools Deposited by Pulsed High Energy Density Plasma
Authors: Miao He Zhuo , Peng Zhi Jian , Qi Long Hao , Shi Feng , Si Wen Jie
Published: March 2009

With a newly-developed technique, pulsed high energy density plasma (PHEDP), TiN, TiCN, and (Ti,Al)N coatings were deposited onto silicon nitride and cemented carbide cutting tools. The structures of these coatings were systematically investigated in this paper. The average surface roughness
(Ra) of the coated tools were ranged in 20~150 nm. The smooth surface of coated tools means that the coatings are promising candidate for cutting tools of high precision and it is in favor of reducing the fiction coefficients and flank wear of tools. The coating thickness varied, in the range of 3~20 µm, with the deposition conditions of the shot number of pulsed plasma, and the voltages between the inner and outer electrodes of the coaxial gun. The coating has a densified structure compared to the substrate structure and almost no pores and cracks exist in the coating surface. The grain sizes of the coating were small (<100nm), much finer than those of the substrate (>2 µm). Except for TiN-Si3N4 system, no apparent columnar grain structure as presented predominantly in typical vapor deposited coatings was observed. In fact, an equiaxed structure was presented, due to the pulsed mode of plasma bombardment and solid solution strengthening of C or Al into TiN lattices, resulting in disruption, through renucleation, of epitaxy on individual columns. A continuous and densified interface was observed. All these
characteristics in structures promised an excellent performance of the coated tools.
High Strength and High Toughness Anisotropic Silicon Nitrides Fabricated by Forging Technique
Authors: Kondo Naoki
Published: March 2009

Grain alignment control to make anisotropic microstructure is one of the most promising techniques to achieve superior mechanical properties in specific directions. Anisotropic silicon nitrides, which were fabricated by a forging technique, can show superior mechanical properties at room temperature as well as at elevated temperatures. A sinter-forged silicon nitride with yttria and alumina additives exhibited very high strength of 2.1GPa at room temperature, meanwhile that with lutetia additive showed high strength of 700MPa at 1500oC. Anisotropic silicon nitrides are also advantageous to achieve higher fracture energy. Such silicon nitrides can show 3~5 times higher fracture energy than isotropic ones. Sinter-forging technique is also applicable to fabricate porous anisotropic silicon nitrides. In this paper, fabrication and mechanical properties of anisotropic silicon
nitrides are briefly described.
Polycarbosilane Conversion Bonded Porous SiC Ceramics
Authors: Zhu Su Min , Wang Ruo Ding , Li Na , Xi Hong'an , Li Qin , Ding Shu Qiang
Published: March 2009

Porous silicon carbide (SiC) ceramics were fabricated by a polycarbosilane (PCS) conversion bonding technique, in which PCS was used as a binder to bond SiC particles with each other. In the preparing process, SiC particles were first coated with PCS, and then the powder compacts were heat-treated in an inert atmosphere. During the heat-treatment, the PCS decomposed and gradually converted to inorganic covalent solids composed mainly of Si-C networks. The
pyrolysis process of PCS, the pore structures and flexural strength of the as-prepared specimens were analyzed and discussed. Preparing temperature as low as 1100°C was adopted in this process and the porous SiC ceramics with a flexural strength of 20 MPa at an open porosity of 43% was obtained. Since PCS was used as a binder, the critical feature of this technique was that the preparation of
porous SiC body was achieved at a low temperature.
Spheroid Growth during Sintering of Copper Coated Silicon Carbide Particles in the Fabrication of Nanocomposite
Authors: Zhang Rui , Wang Hai Long , Gao Lian , Guan Shaokang , Guo Jing Kun
Published: March 2009

Copper coated silicon carbide clusters were used to fabricate nanocomposite. Compacts were isostatically pressed and heated in nitrogen atmosphere. Microstructure observations were carried out to show the spheroid growth of the coated clusters. Spheroid growth was found to proceed through coalescence of smaller spheroids of the coated Cu/SiC composite particles. The densification
process contains steps of agglomeration – kernel-shell formation – slumping movement. Grain growth of the adherent Cu particles is suppressed due to the constraint of rigid SiC particles. This is the deterministic characteristic of the coated composite particles.
On the Theoretical Model for Radar Absorbing Property of SiC
Authors: Tong Xu Guang , Yang Xiao Zhan , Li Jian Bao , Sun Geliang
Published: March 2009

In this paper, the models of multilayer absorbing coating and hollow ball are studied. For the former model, a computer program is made to simulate absorbing results with the electromagnetic transmission line theory. The results show that there is a relevant absorbing peak at different frequencies for different dielectric constant (ε) and the apex’s height and position change with ε and thickness of the
multilayer coatings. This program can predict the coating’s absorbing property efficiently. With the latter model, it is found that SiC hollow micro-balls whose porosity is about 0.89 make the best absorbing effect.
Sliding Friction Behavior of Bulk Ti3SiC2 under Difference Normal Pressures
Authors: Huang Zhen Ying , Zhai Hong Xiang , Zhou Yang , Wang Yi Fan , Zhang Zhi Li
Published: March 2009

The friction behavior of Ti3SiC2 sliding against low carbon steel was studied. Tests were carried out on a block-on-disk type friction tester, with the normal pressures from 0.2 MPa to 0.8 MPa and the sliding speed of 20 m/s. The results showed that, irrespective of the normal pressure, the friction coefficient exhibits a transition period in the initial stage of a sliding friction process, in which the friction coefficient increases from an initial value and tends to a saturation value, and then enters
into a relatively steady stage. The results also showed that, the friction coefficient of the steady stage decreases gradually from 0.35 to 0.26 with increase in normal pressure from 0.2 MPa to 0.8 MPa. The friction surfaces were observed by using SEM. It was found that all the surfaces were covered by a layer consisting of the frictional products with antifriction effect, and that the denseness and the
thickness of the layer were increased with increase in normal pressure applied.
Fabrication and Properties of Ti3AlC2-Based Ceramics by Two-Step Method
Authors: Wang Chang An , Zhou Ai Guo , Peng Chun Qing , Huang Yong
Published: March 2009

A two-step method was presented to fabricate Ti3AlC2-based ceramics. The first step was to synthesize a reactive powder, which mainly contains Ti2AlC, by pressureless sintering (PLS) in argon at 1500°C for 10 mins with a heating rate of 20°C×min-1. The second step was to hot press the powder to a bulk material at 1300°C for 60 mins. The second step not only densified the powder, but also promoted the phase transformation from Ti2AlC to Ti3AlC2. The ceramic sample prepared by this method consists of Ti3AlC2, Ti2AlC and a little amount of TiC. It has excellent mechanical properties: density is 4.26 ± 0.02 g×cm-3, flexural strength is 664.4 ± 90 MPa, Vickers hardness is 6.4 ± 0.5 GPa, and fracture toughness (KIC) is 9.9 ± 0.5 MPa m1/2. The so high values of strength and fracture
toughness are never reported in any literature about this material, as far as we aware.
Study of Ti(C,N)-Based Cermets Fabricated by Pressureless-HIP Sintering
Authors: Ni Xian Juan , Qi Long Hao , Wang Wei , Pan Wei
Published: March 2009

In this paper, the Ti(C,N)-based cermets were fabricated with ultrafine Ti(C,N) powders and metal binders Mo and Ni, in which the ratio of Mo to Ni was 1:1 and total metal content ranged from 10wt% to 20wt%. The specimens were first CIP and pressureless sintered at various temperatures ranged from 1450°C to 1600°C and then treated at 1350°C for 20mins by HIP at the pressure of 140MPa. Results revealed that Post-HIP treatment could dramatically improve the density of specimens if their densities after pressureless sintering could reach the required standard. At the same sintering temperature, the grains became finer with increasing metal contents. The grain sizes increased dramatically with increasing sintering temperature from 1550°C to 1600°C. Compared to those obtained by hot pressing, the cermets obtained by pressureless-HIP sintering had better mechanical properties.
Combustion Synthesis of TiNx C1-x Powders with Ultra Fine Particle Size by Using Titanium Oxide as Dilution
Authors: Ren Ke Gang , Chen Ke Xin , Liu G.H. , Jin Hai Bo , Ning Xiao Shan , Zhou He Ping
Published: March 2009

In present works, the low cost TiO2 powders were partially introduced to raw mixture as playing roles of both reactant and dilution. The experimental results showed that increasing the ratio of TiO2 to titanium powders up to 70wt%, the combustion synthesis reaction could still proceed by self-sustained mode. Single phase of TiNxC1-x with ultra fine particle size could be prepared by using
TiO2 as dilution. Influences of TiO2 addition on phase formation and microstructure of product were also investigated. It was found that the combustion temperature and as-synthesized TiNxC1-x particle size decreased as increasing the amount of TiO2 addition.
Large-Scale (Ti,Cr)B2-Cu Composite by Combustion Synthesis
Authors: Xu Qiang , Zhang Xing Hong , Han Jie Cai , He Xiao Dong
Published: March 2009

Large-scale (Ti,Cr)B2-Cu composite from Ti, Cr, B and Cu powders was produced by combining combustion synthesis with Pseudo Hot Isostatic Pressing. The diameter of the synthesized product is 240 millimeter. The product was identified using X-ray diffraction and the result showed that only (Ti,Cr)B2 and Cu phases, without other phases, existed in the product. The analysis of the microstructure indicated that the skeletal structure had been formed in the (Ti,Cr)B2 solid solution phase. Fine (Ti,Cr)B2 reinforcement grew in near equivalent axis-like shape and some sintering neckings were found between the solid solution phases. The relative density of the synthesized product was 93.6% because the skeletal structure baffled the densification of the composite. The bending
strength and fracture toughness of the product were 476 MPa and 6.8 MPa·m1/2 respectively.
Determination of Sintering Temperature of Nanocomposite WC-Co
Authors: Shao Gang Qin , Yu Xiao-Hua , Duan Xing Long , Zhang Wei Feng , Yi Zhong Lai , Wang Chong , Shun Peng , Shi Xiao Liang
Published: March 2009

The need for WC-Co with improved properties, particularly increased hardness and strength combined with increased ductility and toughness, has focused attention on the development of grades with finer and finer-grained powders and cemented carbides. The aim of this study is to determine the sintering temperature of nanocomposite WC-6Co (wt.%) sample by using an optical microscope under
high temperature and a DSC / TG apparatus. The WC-Co sample was prepared from nanocomposite powder by hot-press-sintering at the determined sintering temperature. The phase structure of the powder and sintered samples was investigated. The SEM imaging was performed on fracture surfaces of sintered
samples. The density and the HRA of sintered samples were also measured.
(Ag1-xNax)(Nb1-yTay)O3 Dielectric Ceramic Prepared through Citrate Precursor Method
Authors: Xiao Mi , Wu Xia Wan , Song Kuan Xiu
Published: March 2009

(Ag1-xNax)(Nb1-yTay)O3 (ANNT) dielectric ceramic material with perovskite structure was prepared through a wet chemical synthetic method. The precursor solution for the material was obtained from the citric acid solutions of different metal oxides or nitrates with exact molar ratio by a sol-process. The precursor solution thus prepared was then heated under an infrared lamp to
evaporate the solvent. This period showed a self-propagating combustion behavior. Ceramic powder was obtained after the residue was calcined at a certain temperature. It is proved that ANNT sintered at 1040°C was finely grained. The obtained ceramic showed excellent high frequency dielectric properties with considerable high dielectric constant and rather low dissipation factor under 1MHz.
Synthesis of Gadolinium Zirconate by Coprecipitaiton and Its Properties for TBC Application
Authors: Wang Cai-Lin , Pan Wei , Xu Qiu , Jiang C.J. , 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 novel
ceramic 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.
Preparation of Porous β-TCP Ceramics
Authors: Chen Hu , Wang Ying Jun , Wang Jian , Nan Kai Hui
Published: March 2009

The processing and properties of porous b-TCP ceramics were investigated. Naphthalene powders used as a pore-making agent. The b-TCP ceramics with a porosity of 75%, a bending strength of 5.3 MPa and pore sizes ranging from 200 ~ 500 µm were obtained. The results showed that the porosity of the ceramics decreased with increasing temperature, while the bending strength increased with increasing temperature. In addition, the phase composition and microstructures of the porous ceramics were examined by x-ray diffraction and scatting electronic microscopy, respectively.
Preparation and Effectiveness of Antibacterial Hydroxyapatite Powder Containing Silver
Authors: Shi C.L. , Ren I. , Xiong Zhao Xian
Published: March 2009

A method of the preparation of an antibacterial ceramic powder is introduced in this paper. Hydroxyapatite is selected to absorb tightly and retain silver for antibacterial ceramic powder. The effect of antibacterial properties against bacterium of S.aureus and E.coli are tested. This antibacterial ceramic has sufficient antibacterial power. The antibacterial effectiveness of this antibacterial powder can reach almost 100%.
Morphology Tailoring of Hydroxyapatite Nanoparticles by Hydrothermal Processing with Amino Acids
Authors: Gao Wei Min , Li Qun Yan , Ruan Cheng Xiang , Chen Yun Fa
Published: March 2009

Hydroxyapatite (HAp) was synthesized in the presence of a variety of amino acids in order to investigate the effect of amino acid on the morphology of HAp obtained by homogeneous precipitation and hydrothermal treating. In the results of X-ray diffraction analysis, HAp synthesized in the presence of some amino acids showed different crystallinity compared with HAp synthesized in the absence of amino acid. The results of Fourier transform infrared spectroscopy suggested the adsorption of these amino acids on HAp. Microphotographs of transmission electron microscope showed that the size and morphology of HAp adsorbed amino acids changed significantly. Collectively, this study suggests that the morphology and the crystallinity of synthesized HAp are different owing to the variation of amino acids in the synthesizing condition.
Preparation of Porous Hydroxyapatite Scaffolds
Authors: Tian Jie Mo , Wang Xiao Yan , Dong Li Min , Wang Chen , Xu Wei
Published: March 2009

Porous hydroxyapatite (HA) ceramic scaffolds were prepared using three-dimensional (3-D) gel-lamination technology with sodium lauryl sulfate as foaming agent and lauryl as foaming stabilizing agent. With gelling system of sodium alginate and calcium chloride, the foamy HA slurry was gelled layer by layer on the 3-D gel-lamination machine to prepare the porous ceramic scaffolds. The viscosity of the foamy ceramic slurry was examined. After sintering, the porous HA bioceramic
was characterized in terms of the porous microstructure and mechanical properties. The experimental results demonstrated that the resultant porous ceramic with appropriate pore size, porosity characters, mechanical properties and bioactivity could be obtained.
Formation of Fe-6.5wt%Si Sheets by Powder Rolling and Sintering
Authors: Zhang Lian Meng , Yuan W.J. , Shen Qiang , Zhang Dong Ming
Published: March 2009

In the present study, Fe-Si sheets were formed by powder rolling of Fe-6.5wt%Si mixture powders, then were sintered in flowing Ar+5vol%H2 atmosphere. The changes in microstructure and density during the formation process were mainly discussed. The results show that Fe-Si mixture powders can be rolled into comparatively compact sheets. During subsequent sintering and re-rolling, the density of the sheet gradually increased and Si diffused into Fe lattice step by step with the increasing of temperature.
Studies on the Improving Performance of Ordinary Concrete
Authors: Xing Feng
Published: March 2009

At present, the concrete applied over the world is ordinary concrete with a compressive strength less than 50 MPa, whose service life is generally 40 ~ 50 years. How to get high performance, high durability, and make its service life extend from 40 ~ 50 years to 70 ~ 80 years is of great significance in saving resources, energy and money. From the point of view of material science, the durability of
concrete is mainly affected by its components, inner structure and performance. This paper studied how to adjust the components and add special mineral ultra-finest powder to make the ordinary concrete get higher durability and performance.
The Brazilian Reliability Test and Micromechanical Modelling for Channelled Cylinders of Multiphased Porous Ceramics
Authors: Osterstock Frédéric , St. Doltsinis Ioannis , Vansse Olivier
Published: March 2009

Channelled hollow ceramic cylinders have been sliced into discs of equal thickness and submitted to an adapted diametral compression, or brazilian, test such as to evaluate their reliability. The mean Weibull modulus, of m » 18, is representative of a rather good homogeneity of the ceramic material. The shapes of the distributions reveal a probable multimodality. This is analyzed in superimposing possible unimodal distributions of given characteristic value, Weibull modulus and number of items, and comparing to the experimental plot. Iterative modifications are made until a convincing superposition is attained. Complementary numerical simulations on “thermomechanically equivalent microstructures” have been created on the computer observing actual stereological data. The micro-mechanical model accounts for cracking of grain interfaces until specimen separation.
Weibull plots for model structures under pore pressure suggest multimodal distributions with moduli ranging as in the measurements. The larger scatter at higher rupture pressures may indicate a varying degree of quasi-brittleness.
A Tensile-Load Relaxation Test for Measuring the Stress Enhanced Corrosion Exponent of Ceramics with Open Porosity
Authors: Osterstock Frédéric , Vansse Olivier
Published: March 2009

A tensile test is proposed for evaluating the stress enhanced corrosion-coefficient of ceramics with open porosity. The analysis of load at fixed grip conditions bases on the assumption that stress corrosion results in a spread of pre-existing generalised damage seen as micro-crack starter due to open porosity. Sub-critical crack extension of microcracks departs from pores and provokes a time dependant
diminution of the Young’s modulus, and of the stiffness, of the tested sample. The description derives the number and the size of pre-existing micro-cracks with respect to time. The density of microcrack-nuclei results from the process and belongs to the microstructure, i.e., the number of channels or crack starters,
and is considered to remain constant. The rate of diminution of the load is considered, either with respect to the initial one or to a deduced stress intensity factor. Simple relationships yield then an approximate diagram for stress enhanced corrosion. Samples resulting from sintering a mixture of alumina and titania
powders were tested under tempered water flow. A stress corrosion exponent, n = 16, near to that of alumina was obtained.
Description of Unloading Behavior of Berkovich Nanoindentation
Authors: Miao He Zhuo , Gong Jiang Hong , Peng Zhi Jian
Published: March 2009

We established a new expression to describe the nanoindentation unloading data by
assuming that the Berkovich indenter behaves as a conical punch, rather than a paraboloid punch, and properly considering the effect of residual contact stress on the unloading load-displacement relation. The validity of this new approach was confirmed by analyzing the experimental data obtained for a series of brittle materials. It was shown that, compared with the generally adopted power law, this new expression has much clearer physical significance.
Textured Pb(Mg1/3Nb2/3)O3-PbTiO3 Ceramics by Templated Grain Growth
Authors: Chen Ke Pi , Duan Wen Hui , Gu Bing Lin , Qiao Liang , Zhou He Ping , Zhang Xiao Wen
Published: March 2009

Fiber textured 0.70PMN-0.30PT ceramics was fabricated using the Templated Grain
Growth (TGG) process. Tabular SrTiO3 particles synthesized in molten NaCl-KCl salts were used as templates and oriented in fine 0.70PMN-0.30PT matrix during rolling. Tabular SrTiO3 particles can stabilize in sintering by SPS technique and annealing. A degree of [001] texture (Lotgering factor ~ 0.38) was obtained by heteroepitaxial growth of oriented single PMN-PT on the SrTiO3 template
particles.
Application of Materials Design Based on Genetic Neural Network
Authors: Zhang Yilai , Li Xue Jian , Zeng Ling Ke , Chang Cheng Kang
Published: March 2009

Neural network (NN) is an effective method in the filed of materials design, but the
convergent speed is decided by initial weights. This paper proposes genetic neural network algorithm (GNNA) to design materials. Aluminum titanate modification is studied by the method of GNNA. The results indicate the algorithm works well.
Multi-Layer Silicon Nitride Laminates Exhibiting High Fracture Toughness and Crack Deflection
Authors: Blugan Gurdial , Orlovskaya Nina , Lewis Mike , Kübler Jakob
Published: March 2009

Si3N4-TiN based multi-layer ceramics laminates have been produced. With external
compressive layers, laminates with a three-fold increase in KIc over the monolithic ceramics have been realised. When external tensile layers are used in conjunction with thin internal compressive layers, energy absorbing crack deflection and bifurcation processes are observed.
Effects of Ti4+ Substitution on Microstructure and Microwave Dielectric Properties of ZnNb2(1-x)TixO(6-3x) Ceramics
Authors: Zhang Ying Chun , Yue Zhen Xing , Wang Jin , Gui Zhi Lun , Li Long Tu
Published: March 2009

The microstructure and microwave dielectric properties of dielectric ceramics comprised of ZnNb2(1-x)TixO(6-3x) (x = 0 ~ 1) were investigated systematically using X-ray powder diffraction, SEM and a network analyzer in this study. The results showed that four phases were observed in this system. The dielectric properties at microwave frequencies exhibit a significant dependence on the composition and crystal structure of the ceramics. The dielectric constant ( er) of ZnNb2(1-x)TixO(6-3x)ceramics increases with increasing Ti content and the quality factors (Q ×f) significantly decreased. However, the temperature coefficient of resonant frequency ( t f ) changes from –59.08 ppm/oC at x = 0
to + 25.1 ppm/oC at x = 1, and a zero temperature coefficient of resonant frequency ( t f ) for this ceramics system was obtained at x = 0.84.
Application of Ceramics Metal Functionally Graded Materials on Green Automobiles
Authors: Li Yong , Jian Song , Min Zhi
Published: March 2009

Ceramics metal functionally graded materials (FGM) is applied on the dual friction pair of the green automobiles. The structure and component characteristics of FGM are better, compared with traditional Ceramics. Even with the same components, FGM bears an outstanding mechanical performance and its cracking strength, toughness and fatigue strength are relatively superior. The influence of Ceramics metal functionally graded materials on the performance of automobiles are analyzed via a comparative research and comparison of the external characteristics of automobile is made in terms of mechanism. The results indicate that the power output, fuel consumption and durability are improved considerably on the green automobiles. Improvement is also made on the wearing capability, lubricity and sealing performance as well. Hence comes the reduction of friction loss and leakage loss. The principal abrasion mechanism of FGM is plastic flowing and the secondary are brittle failure and grain abrasion.
Effect of Sr Doping on Piezoelectric Properties of Pb(Mn1/3Nb2/3)O3-Pb(Zr,Ti)O3 Ceramics
Authors: Li Bao Shan , Li Guo Rong , Zhu Zhi Gang , Zhang Wang Zhong , Yin Qing Rui , Ding Ai Li
Published: March 2009

This paper aims at the determination of the effects of strontium addition on the microstructural evolution and the piezoelectric properties for Pb(Mn1/3Nb2/3)O3-Pb(Zr,Ti)O3 (PMnN-PZT) ceramics. The Sr content was chosen in the range of 2-8 mol%. These materials were prepared by the solid phase reaction of the oxides. It was found, from the experimental results, the tetragonality of the PMnN-PZT lattice and the Curie temperature decreased with Sr content; in the meantime, dielectric constant increased greatly. Dielectric constant (er) and planar coupling factor (Kp) was proven to be dependent on sintering temperature. P-E curves of PMnN-PZT system exhibited some “pinched” shape instead of the normal square-like P-E loops, illustrating presence of the oxygen vacancies by reason of the preferable substitution of the B-sites ion.
Preparation of PMZN Piezoceramic Using Sol-Autocombustion Synthesized PZT Powder as a Base
Authors: Sun Hua Jun , Chen Wen , Xu Qing , Zhou Jing , Liu Xiao Fang
Published: March 2009

Using Zr(NO3)4.5H2O as Zr source, PZT powder with a single-phase perovskite structure was synthesized by a sol-autocombustion method at a calcining temperature of 700°C. Compared with a solid-state reaction method, the calcining temperature of PZT can be lowered by 200°C when using the sol-autocombustion method. PMZN ceramic was prepared at a sintering temperature of
1050°C with the resulting PZT powder as a base, which can lower the sintering temperature by 150°C. The microstructure of the PMZN ceramic was investigated by XRD and SEM, and the dielectric and piezoelectric properties were measured. The results showed that the PMZN piezoelectric ceramic has a tetragonal perovskite structure, showing the main electrical properties as follows: Kp = 0.54, Qm = 1073, tgd £ 0.001, e33 T/ e0 = 1236, d33 = 454pC/N, and fs =136.1KHz.
Influence of Film Thickness on Optical Properties of PLZT Thin Films Derived from MOD Method
Authors: He Xi Yun , Ding Ai Li , Zhang Yong , Cao Zi Ping , Qiu Ping Sun
Published: March 2009

PLZT (9/65/35) thin films on sapphire (001) substrates with thickness of 0.1 ~ 0.9 µm were prepared by a metal-organic decomposition (MOD) process. All the films present highly (110)-preferred orientation independent of the film thickness. The microstructure of the films was investigated. The influence of film thickness on optical properties of PLZT films was examined and analyzed. As the film
thickness is increased, the absorption edge of the film is shifted to longer wavelength; the optical band gap Eg is increased slightly. The refractive index at 510nm determined from optical transmission spectra also shows an increasing tendency as film thickness increasing. Great stress aggregated during the film
preparing process is thought to be an important reason which results in the variations of optical properties of the films with different thickness.
Grain Size Effects of SnO2 Varistor Induced by Doping Pr
Authors: Zhang Cheng Ju , Wang Jin Feng , Su Wen Bin , Zang Guo Zhong , Chen Hong Cun
Published: March 2009

The effects of Pr on the microstructure and nonlinear electrical properties of the (Co,Ta)-doped SnO2 varistors were investigated. It was found by characterizing the samples sintered at 1350 oC that the breakdown voltage increases significantly from 500v/mm to 1200v/mm, and the relative permittivity decreased rapidly from 2525 to 1199 with increasing Pr6O11 concentration from 0 to 1.20 mol%. The
analysis of samples’ microscopic structure showed that the grain size of SnO2 rapidly decreases from 5.1 to 3.7 µm with increasing Pr6O11 concentration from 0 to 1.20mol% .The significant decrease of SnO2 grain size is the main reason for raising breakdown voltage and reducing permittivity.
Antistatic Ceramic Tiles Modified by Sb-Doped SnO2
Authors: Wang Yong Qing , Wu Jian Qing , Zhou Jianer
Published: March 2009

Antistatic ceramic tiles was prepared by adding 15wt% or more synthesized Sb-doped SnO2 into their glazes. The tiles have the surface resistivity ρs of 1.40 × 106 to 5 × 108 Ω×cm. The conduction mechanism was analyzed and it was shown that the electrostatic charges are eliminated by the network formed by the Sb-doped SnO2 distributed in the glaze.
Nonlinear Electrical Properties of (Sc, Ta) Doped TiO2 Varistor Ceramics
Authors: Su Wen Bin , Wang Jin Feng , Chen Hong Cun , Zang Guo Zhong , Qi Peng , Wang Chun Ming
Published: March 2009

The nonlinear electrical properties of TiO2-based varistor doped with 0.25mol% Ta2O5 and different contents of Sc2O3 were investigated. It was found that the TiO2 varistor ceramic doped with 0.10mol% Sc2O3 exhibited an optimal nonlinear coefficient of 7.8, a breakdown electrical field of 16.0V/mm, and relative dielectric constant of 1.27 × 105 (measured at 1 kHz). In order to analyze the effect of Sc2O3 on TiO2 varistors, studies were made on the capacitance versus voltage characteristics. A Schottky-type barrier, which is assumed as the origin of varistor behavior, was inferred from the C-V measurement. The barrier height and donor concentration were obtained as 0.41eV and 1.21 × 1026cm-3, respectively, for sample doped with 0.10mol% Sc2O3. Analogized to the ZnO varistors, the
formation mechanism of Schottky-type barrier was discussed in this paper by the theory of defect in crystal lattice.
Ag Nanoparticle Enhanced Photocatalytic Activity of Rutile TiO2 Films Prepared by Electrostatic Self-Assembly Method
Authors: Pan Feng , Zhang Jun Ying , Liu Hai Ying , Wang Tian Min , Hao Wei Chang
Published: March 2009

Ag nano-particles were deposited on the surface of TiO2 self-assembled films by
photo-reduction of Ag+ solution. SPM, XPS and UV-Vis spectrophotometer were employed to characterize the microstructure and photo-catalytic performance of the films. An obvious enhancement of photo-catalytic activity had been observed. Since rutile had a lower optical band gap than anatase, a higher photo-catalytic efficiency improvement of rutile than that of anatase was obtained under the help of Ag nano-particles, which acted as electron acceptors.
Study on the Gas Sensitivity of a CeO2 Based Ceramic Sensing Element: Structure and Characteristic
Authors: Yan Tao , Liu Xiao Lin , Chen Jian Feng
Published: March 2009

The sensitivity of CuO dispersed on fluorite-type oxide, namely CeO2 was studied in this work. Mixed oxide sample of nanostructured CuxCe1-xO2-y of various composition were generated by step chemical precipitation method. Distinct copper species were identified as a function of copper content by X-ray photoelectron spectroscopy, X-ray powder diffraction, the special surface areas, transmission
electron microscopy, scanning electron microscopy analysis, and sensing properties to CO. It was found that only small amounts of copper are sufficient to promote the sensitivity of CeO2 by several orders of magnitude, which excessive amounts of copper (Cu/(Cu+Ce)>0.12) are detrimental to the sensing
properties of nanocompositions. The possible causes for this behavior are also discussed.
Preparation and CO2 Gas Sensitive Properties of CuO-SrTiO3-Based Semiconductor Thin Films
Authors: Gu Yan Fei , Ji Hui Ming , Zhang Bin , Xu Ting Xian
Published: March 2009

CuO-SrTiO3-based thin films were prepared by novel sol-gel technology on Al2O3 substrates using Cu(NO3)2, SrCl2 and TiCl4 as the starting materials, critic acid and ethylene glycol as chelating agents. CO2 sensing properties of the films were investigated. Structure characteristics of the sol and asgrown thin films were analyzed by FT-IR spectrum, X-ray diffraction and SEM. The results reveal that
the films consisted of CuO phase and SrTiO3 phase have nanocrystalline microstructure at 750°C for 40 min. The modified CuO-SrTiO3 thin films exhibit good resistance-temperature and gas sensitivity properties in a wide range of temperature. The films exposed to 6% CO2 show that sensitivity are 32, and
response and recover time are within 2 s at 250 °C operating temperature.
Effects of Mg2+ on Microstructure and Microwave Dielectric Properties of La2/3TiO3 Ceramics
Authors: Yang Ai Min , Chen Wei , Luo Lan
Published: March 2009

(1-x)La2/3TiO3-xLa(Mg1/2Ti1/2)O3 ceramics with x ranging from 0.01 to 0.3 were prepared by the conventional solid-state reaction method. Microstructure and microwave dielectric properties were studied. The perovskite compound La2/3TiO3 is stabilized when x = 0.1. The content of La2/3TiO3 increases with increasing x from 0.01 to 0.1, and thereafter decreases when x > 0.1. The same tendency was also observed on measuring the dielectric constant, temperature coefficient of resonant frequency and Q× ƒ. A maximum permittivity of 77.35 was achieved with these stabilized La2/3TiO3 ceramics. Close to zero τf value (1 ppm/°C) was obtained at x=0.3, but its Q× ƒ value was relative low.
Electrical Properties of BaTiO3 Doped with Lanthana and Niobia
Authors: Mosaad M.M. , Abd El-Ati M.I. , Olofa S.A. , Ismal A.
Published: March 2009

The electrical resistivity (r), the dielectric constant (e), and the dielectric loss (tan d) were accurately measured in the temperature range 60-200oC for the samples (BaTiO3-La2O3-Nb2O5) with (Nb2O5 = 0.1) wt% and La2O3 = 0.0, 0.1, 0.2, 0.3 and 0.4). It is found that the addition of La content cause increase in resistivity and decrease the dielectric constant.
Preparation and Electrical Properties of Ternary Compound (PbTe)1-x(SnTe)x with Nanocrystallines
Authors: Cui J.L.
Published: March 2009

Ternary compounds (PbTe)1-x(SnTe)x with nanocrystallines were synthesized at a temperature of 180oC by conventional solvothermal method. XRD analyses revealed that relatively pure compounds can be synthesized using ethylenediamine as a solvent only when a reaction time of at least 24h is applied. The XRD results are in agreement well with those from EMPA analysis. The
grain sizes of the materials, ranging from 50~70nm, are slowly increased with reaction time. Measurements showed that the maximum power factor of about 6.0×10-4 W.m.K-2 for the synthesized materials are higher than that of similar material prepared by vacuum melting.