bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Pr6O11 Doped Zinc Varistors by High-Energy Milling
Authors: Qi Guo Quan , Zhu Jian Feng , Mao Hai Bo , Wu Yang , Yang Hai Bo , Wang Fen
Published: April 2010

High voltage zinc varistors was synthesized by high energy milling with Pr6O11 doped ZnO-Bi2O3 system as raw materials. The effects of milling time and sintering temperature on the electrical properties were investigated. The results show that high-energy milling decreases the sintering temperature of the ZnO varistors. The material derived from high-energy milling exhibit high density and good electrical properties at the sintering temperature from 1080 to 1180°C. The samples sintered at 1100 °C have average crystalline grain size of about 5 µm with the optimum values of electrical properties, gradient voltage V1mA is 371 V/mm, leakage current IL is 0.62 µA, non linear coefficient α is 60.
Influences of Sintering Temperature on Microstructure and Electrical Properties of TiO2 Varistor Ceramics
Authors: Chen Yan Yan , Zou Ming , Wang Yuan , Zhang Yun
Published: April 2010

Influences of sintering temperature on microstructure and electrical properties of TiO2 varistor ceramics were investigated. Morphologies of TiO2 ceramics samples were characterized using scanning electron microscope. The phase composition and crystal structure were researched by X-ray diffraction. The frequency dependences of the samples capacitance were determined using LCR meter, the varistor voltage V1mA and nonlinear coefficient α were discussed by experimental method. The results showed that TiO2 ceramics sintered at 1350°C for 2 h possesses fine microstructure and optimal electrical properties. However, the electrical properties of samples will deteriorate as excessive sintering temperature.
Effects of Sintering Temperature on Microstructure and Properties in TiO2 Varistor Ceramics
Authors: Yan Ji Kang , Gan Guo You , Du Jing Hong , Sun Jia Lin
Published: April 2010

The effects of sintering temperature on microstructure, micro-composition, barrier structure and electrical properties of TiO2 varistors ceramics were investigated. The microstructures and chemical compositions of grains in TiO2 ceramics were measured by SEM and EDS. Based on the thermo electronic emission theory, Grain boundaries barrier structure was calculated by analyzing electrical properties of samples. The sample sintered at 1350°C exhibits better microstructure and properties. The grains size of the TiO2 sample sintered at 1350°C is about 15m, and other electrical properties are as follows: solid solubility of donor doping Nb5+ cation solute in TiO2 grains of 1.49mol%, barriers height of 0.28ev, barriers width of 48nm, varistor voltages of 5.25V/mm, non-linear coefficient of 4.2 and relative dielectric constant of 1.1×104.
Preparation and Thermoelectric Properties of SiC Matrix Composites Prepared under a Low Sintering Temperature
Authors: Li Ming Liang , Wang Hai Long , Zhang Rui , Li Jing , Li Jun Hao
Published: April 2010

SiC powders with nickel powders and sintering aids were prepared by pressureless sintering at 1500oC under a N2 atmosphere. XRD, TEM, SEM techniques were used to characterize the phases and microstructure of the specimens. The thermoelectric properties of SiC matrix composites were investigated by measuring the Seebeck coefficient and the electrical conductivity. The main phase of all samples was -SiC, the Ni2Si can be observed with adding nickel powders. The largest electric conductivity was close to 3.5 m-1-1 at about 973K. The highest Seeback coefficient was up to 1800 V/K at 1073K. The transition from n-type to p-type was occurred.
High-Temperature Thermoelectric Properties of Pb- and La-Substituted Bi2Sr2Co2Oy Misfit Compounds
Authors: Hao Hao Shan , Ye Jin Qin , Liu Yong Tao , Hu Xing
Published: April 2010

Pb- and La-substituted (Bi,Pb)2(Sr,La)2Co2Oy samples were prepared by solid-state reaction method and the effect of element substitution on the high-temperature thermoelectric properties was investigated. It was found that the presence of Pb and La elements improved the thermoelectric properties of the Bi2Sr2Co2Oy system owing to the simultaneous increase of conductivity and Seebeck coefficients. The optimal thermoelectric performance was obtained in Pb and La co-substituted samples and the power factor could reach 2.1×10-4Wm-1K-2 at 1000K.
Preparation of PbTiO3-Based Conductive Ceramic Powders by Gaseous Penetration of Rare Earth
Authors: Hao S.E. , Fu D.S. , Li J.L. , Wang C.Y.
Published: April 2010

The new type PbTiO3 based ceramic conductive powders were prepared with a special technology, gaseous penetration, which is making rare earth La penetrate into PbTiO3 powders in the gaseous state at high temperature. Through XRD analysis, it is found that there are some new compounds such as LaTiO3 and LaTi3O49 formed after penetration of La, which indicates that the gaseous penetration made La element enter PbTiO3 powders and the complex reactions took place during the penetration process. Through SEM, it can be deduced that the rare earth elements occupied the atom vacancies, formed the new phases and made the grains of La-penetrated PbTiO3 based powders become smaller and finer with less pores and appeared as dispersing structure. All these led to a significant change in electric conductivity, and when the La3+ content in the solvent was 0.02, the penetration temperature was 950°C and the penetration time was 4h, the resistivity at room temperature was the smallest, which decreased from 8.3×108Ω.m to 8.2×10-4Ω•m.
Orientation Growth and Optical Properties of Sm2O3 Thin Films
Authors: Yin Li Xiong , Huang Jian Feng , Huang Yan , Cao Li Yun
Published: April 2010

Sm2O3 optical thin film is a new photovoltaic material and has potential applications in optical switches, date recording device and magnetic device. Using samarium dichloride as raw material, Sm2O3 optical thin films were prepared by sol-gel and hydrothermal process on glass and Si (100) substrates. The phase compositions, morphologies and optical properties of the as-prepared thin films were analyzed by X-ray diffraction (XRD), atomic force microscope (AFM) and UV-vis spectrophotometer (UV-vis). Results show that the Sm2O3 thin films prepared by sol-gel method exhibit an obvious (110) orientation growth on glass substrates, while the Sm2O3 thin films prepared with hydrothermal method have no obvious orientation. The as-prepared films have excellent absorbency of UV light and are transparent to visible light. The band gap of the Sm2O3 films prepared by hydrothermal method is narrower than that of those obtained by sol-gel method. The absorbency of UV light and transparence to visible of the Sm2O3 films prepared by sol-gel method are obviously improved in comparison with those deposited by hydrothermal process.
Effect of Deposition Voltage on the Composition, Morphology and Optical Properties of ZnS Thin Films Prepared by Cathodic Electrodeposition
Authors: Zhu Hui , Huang Jian Feng , Cao Li Yun , Wang Yan , Zeng Xie Rong
Published: April 2010

Zinc sulphide (ZnS) thin films were deposited on the indium tin oxide (ITO) substrates by a novel, simple cathodic electrodeposition method under atmospheric pressure. These thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and photoluminescence spectrum (PL) at room temperature. The effects of deposition voltage on the phase composition, morphology and photoluminescence behavior of the thin films were investigated. XRD analysis shows that the deposited thin films is highly preferential growth along (200) orientation. Both AFM and XRD analyses indicate that the surface of the ZnS thin films is composed of uniform grains of around 50 nm in diameter. With the increase in the deposition voltages, the crystallization of the obtained thin films improves and the grain size of the ZnS thin films increases. Photoluminescence emission peaks are observed at at 475~490 nm and 500 ~530 nm at room temperature for an excitation of 210 nm.
Preparation and Optical Properties of TiO2 Nanotube Arrays by Anodic Oxidation Method
Authors: Wang Zhu Mei , Chen Yun Xia , Li Yue Ming , Zuo Jian Lin
Published: April 2010

Titania nanotube arrays were fabricated by anodic oxidation of a pure titanium foil. The morphology, structure and optical properties of the nanotube arrays were characterized by SEM, XRD and UV-Vis spectrum. The effect of anodic oxidation parameters on the morphology was investigated. The growth mechanism of the titania nanotube arrays was discussed. The results show that the vertical oriented TiO2 nanotube arrays can be obtained at 20V for 60min in 0.5wt%HF+1mol/L H3PO4 solution. The aperture size of nanotube is 60nm~80nm and the thickness of tube wall is about 10nm. The spectral absorptivity of TiO2 nanotube arrays membrane calcined at 600°C towards ultravlolet light 349.7nm and visible light 443.9nm was relatively higher. It is also found that the crystal structure is greatly affected by calcining temperature.
Preparation and Electrical-Conductive Property of SnO2-Based Ceramics
Authors: Luo Guo Qiang , Shen Qiang , Li Q.Z. , Li J. , Zhang Dong Ming , Zhang Lian Meng
Published: April 2010

In this study, SnO2-based ceramics, with CuO as sintering aid and Sb2O3 as activator of the electrical conductivity, was obtained by pressure-less sintering at 1100°C ~ 1470°C. Addition of antimony leads to a higher densification temperature. Densification behavior and microstructure development are strongly dependant on CuO and Sb2O3. CuO gives rise to a liquid phase; Sb2O3 retards the formation of liquid phase and hinders the growth of grain. The electrical resistivities of SnO2-based ceramics vary in a wide range from 10-2 to 107 Ω•cm, depending on starting compositions and processing conditions. The electrical resistivities of samples with different amounts of CuO and Sb2O3 show different trends with the increasing of sintering temperature. The addition of antimony rapidly promotes electrical conductivity of SnO2-based ceramics containing CuO as the solid solution reaction of Sb2O3-SnO2. As the additions of CuO and Sb2O3 are the same, the electrical resistivity arrives the minimal value of 4.72×10-2 Ω•cm for 99%SnO2+0.5%CuO +0.5%Sb2O3 at 1470°C. More content of Sb2O3 than CuO causes the degression of density and the rising of electrical resistivity of ceramics.
Forming Mechanism of Dy2Ce2O7 Ceramic for Thermal Barrier Coatings
Authors: Zhang Hong Song , Hu Ren Xi , Xu Qiang
Published: April 2010

The forming mechanism of Dy2Ce2O7 prepared by solid reaction using CeO2 and Dy2O3 as reactants was analyzed by X-ray diffraction method. It is indicated that there is almost no solid solution reaction between Dy2O3 and CeO2 before 1300°C, the Dy3+ cations enter the crystal lattice of CeO2 and substitute sites of Ce4+ cations in the range between 1300°C and 1400°C which resulted in the formation of Dy2O3-CeO2 solid solution. The Dy2O3-CeO2 solid solution transformed gradually into Dy2Ce2O7 after 1400°C and pure Dy2Ce2O7 can be obtained at 1500°C. No other intermediate phases were found in the whole process.
Finite Element Analysis on Cooling Process of SHS Reactive Flame Spray Surface Coating
Authors: Hu Wen Bin , Zhang Long , Wang Jian Jiang , Ye M.H.
Published: April 2010

Numerical simulation the temperature and stress of the SHS reactive flame spray coatings which were cooled in air and sand from a high temperature to room temperature (25°C). The distribution of temperature and stress of the coatings were discussed. The results show that the cooling velocity of air-cooled product is fast than that of sand-cooled product; temperature distribution of sand-cooled product is more uniform than that of air-cooled product in the process of cooling; the stress state of air-cooled coating is tensile stress state, while the stress state of sand-cooled coating is compressive stress state; the stress distribution and strain situation are close relative to temperature distribution, heat emission speed and geometric shape of products in process of cooling; the smooth geometric shape of the product, uniform temperature distribution and heat emission speed are beneficial to improve the state of residual thermal stress; the stress and strain state of sand-cooled coating is better than that of air-cooled coating.
Preparation and Physical Properties of SrxLa1-xMgAl11O19-0.5x
Authors: Yao Hua Dong , Xu Qiang , Liu Ling , Zhu Shi Zhen
Published: April 2010

In order to further improve the thermal expansion coefficient of LaMgAl11O19, LaMgAl11O19 with Sr2+ doped is designed to increase the density of oxygen vacancies, and the effect of doping Sr2+ to hardness and toughness was studied. SrxLa1-xMgAl11O19-0.5x pellets were synthesized by hot-pressing (1500°C, 40MPa). The relative density of LaMgAl11O19 reaches 97.68%. The hardness of LaMgAl11O19 is about 25.47GPa and the fracture toughness is 11.3 MPa•m1/2. The thermal expansion coefficient of LaMgAl11O19 was 8.71×10-6K-1, and Sr0.6La0.4MgAl11O18.7 was 8.95×10-6K-1. The results showed hot-pressure sintering could synthesize dense SrxLa1-xMgAl11O19-0.5x with magnetoplumbite structure. Sr2+ doping could increase the thermal expansion coefficient of LaMgAl11O19.
Fabrication of Multiple Oxidation-Resistant Coating on C/SiC Matrix
Authors: Huo Yan Li , Chen Yu Feng , Tang Jie , Liu Hai Lin , Wang Chun Peng
Published: April 2010

Oxidation-resistant coatings with gradient structures on C/SiC composites were fabricated. The gradient oxidation-resistant coatings were composed of three layers. The inner layer was reaction-bonded SiC which was fabricated by silicon infiltration. The middle layer was dense CVD SiC with the gradient component which was produced by the pyrolysis of methyltrichlorosilan (MTS) in excess hydrogen. The outer layer was a sealed layer with B4C and MoSi2 powders which was fabricated by slurry process. Optical microscope and SEM were used to observe the cross-section morphology and microstructure of coatings. XRD and EDS were used to characterize the phase composition and component distribution of coatings. EDS analysis showed the component distribution of CVD SiC coating changed significantly with the change of ratio of MTS to H2. The result indicated that C/SiC composite had good oxidation resistance when it was used at high temperature in the environment of high-speed combustion gas.
Effect of Sm2O3 Additives on the Rod-Like β-Si3N4 Crystal of Porous Silicon Nitride Fabricated by Reaction-Bonded
Authors: Yue Jian She , Wang Hong Jie
Published: April 2010

Sm2O3 and MgO as a sintering additives to fabricated porous silicon nitride by reaction-bonded. The phase of as-produced silicon nitride characterized by XRD-diffraction. The microstructure of product was investigated by SEM. The samples were machined into test bar for flexural strength testing. Using Archimedes theory testing the porosity of porous silicon nitride. MgO have restrain effect on the growth of rod-like silicon nitride, because of produce a restrain layer which is MgO reacted with SiO2 on the surface of silicon., the microstructure of crystal is particle like, the maximum flexural strength is 48MPa with porosity of 35%. Sm2O3 can assistant the growth of high aspect ratio Si3N4 crystal at beginning temperature of 1300°C for it’s low melt point and low viscidity in liquid state, the as-product’s morphology is rod-like and the flexural strength is as high as 300 MPa when the porosity is 30%, high than the sample that of low rod-like crystal content.
Cr-Doped DLC Multilayered Thin Films Deposited Using Cathodic Vacuum Arc- and DC Magnetron-Assisted Ion Beam Sputtering
Authors: Chen Xin Chun , Peng Zhi Jian , Fu Zhi Qiang , Wang Cheng Biao
Published: April 2010

A series of graded films of Cr/CrN/ CrNC/CrC/(Cr-DLC)/[(Cr-(Cr-DLC))×10] were deposited on Si(100) wafer and 4135 alloy structural steel using cathodic vacuum arc technique and direct current magnetron sputtering method combined with ion beam sputtering. The surface morphology, microstructure, nano-hardness, adhesion and wear properties of the films were investigated using 3-dimensional white-light interfering surface profiler, scanning electron microscopy, nanoindentation, scratch adhesion test, ball-on-disc test, etc. It was measured that the as-prepared Cr-doped DLC multilayered thin films have a strong adhesion to the substrates with a critical load exceeding 80 N, and the average friction coefficient during 30 min test in air was 0.23. This film will be promising in application against wear.
Tribological Behavior of Polyimide/Zinc Oxide Hybrid Films
Authors: Liu Bin , Yang Zu Hua , Zhou Jian Song
Published: April 2010

A series of polyimide/ZnO films were successfully prepared via a solution process. The friction and wear behavior of the hybrid polyimide films in dry sliding against Si3N4 ball was examined on a DF-PM ball-on-block unidirectional friction and wear test rig. The worn surface morphologies of the films were observed with a scanning electron microscope. It was found that the introduction of zinc oxide led to improving the tribological characteristics and thermal stability of the polyimide films. The polyimide/zinc oxide hybrid films had much better friction-reducing ability and wear-resistance than the neat PI film.
Preparation and Property of Ceramic Matrix Coating of Anti-Oxidation for Stainless Steel at High Temperature by Slurry Method
Authors: Liu Peng , Wei Lian Qi , Ye Shu Feng , Zhou Xun , Xie Yu Sheng , Chen Yun Fa
Published: April 2010

In this paper, the new high temperature ceramic matrix coating of anti-oxidation for stainless steel was prepared by slurry method. With the research about oxidation resistance of ceramic matrix coating formed on stainless steel, the effect of initial melting temperature, melting temperature range and thermal expansion coefficients of ceramic sintering change on protective properties of high temperature coating prepared at 1250°C is investigated, and then high temperature sintering ceramic with high-performance is gained through optimization. Through the test of TG-DTA and XRD to the coating, study on high temperature oxidation resistance of ceramic coating and the structure changing of the scale with coating from SEM images and photos, it is shown that the ceramic coating has excellent oxidation resistant properties, the weight loss with coating decrease more than 85%.
Preparation of Y2O3-Al2O3-ZrO2 Nano-Ceramic Coatings on Metal Substrate by Sol-Gel Method
Authors: Hou Xi Feng , Peng Peng , Liu Yan Gai , Fang Ming Hao , Huang Zhao Hui
Published: April 2010

In this paper, Y2O3-Al2O3-ZrO2 nano-ceramic coatings were prepared on 316L stainless steel substrate at 600°C for 0.5 hour by sol-gel method, using Y(NO3)3•6H2O, ZrO(NO3)•2H2O and Al(NO3)3•9H2O as raw materials, hexamethylenetetramine as catalyst. Phases and morphology of these coatings were characterized by XRD, SEM and EDS. Effect of heat treatment temperature on microstructure of the coatings was studied. Y2O3-Al2O3-ZrO2 coatings with grain size about 50nm tightly integrated with metal substrate after densely sintering at 600°C. The grain sizes have grown up with increasing temperature.
Morphology of In Situ VC Ceramics in High Speed Steel with High Vanadium Content
Authors: Xu Liu Jie , Chen Hui Min , Wei Shi Zhong , Long Rui
Published: April 2010

The morphology and distribution of in-situ VC ceramics in cast high speed steel with about 5-10wt.% vanadium and 1.7-3.2wt.% carbon were studied. The results show that the elementary morphology of in-situ VC ceramics has six kinds: spherical, lumpy, flower shaped, strip, short rod shaped, and vermicular. The in-situ VC in high-speed steel has three kinds of distributions: grain boundary, chrysanthemum-like and homogeneous distributions, depending on the chemical composition of high-speed steel. The in-situ VC ceramics grows up along grain boundaries if the high-speed steel is hypoeutectic, leading to grain boundary distribution of VC ceramics. On the contrary, it distributes homogeneously when the high-speed steel is hypereutectic. Whereas, the in-situ VC ceramics takes on chrysanthemum distribution if the high speed steel is just eutectic. Modification can improve the morphology of primary VC ceramics, but has not obvious effect on the morphology of eutectic VC.
Influence of Deposition Voltage on Microstructures of Yttrium Silicates Coatings by Hydrothermal Electrophoretic Deposition
Authors: Wang Ya Qin , Huang Jian Feng , Cao Li Yun , Zeng Xie Rong
Published: April 2010

Yttrium silicates oxidation resistance coatings were deposited on SiC-C/C composites surface by a hydrothermal electrophoretic deposition process. The influence of deposition voltage on the yttrium silicates coatings and the deposition amount of coatings were particularly investigated. Results show that with the increase of deposition voltage, the deposition amount of coatings increase, the density and uniformity of the coating surface is improved. When the deposition voltage reaches 210V, dense yttrium silicates coatings are achieved. While increase the deposition voltage continually, the uniformity of coatings decrease. When the deposition voltage arrives to 240V, high deposition voltage will result in cracked coatings. There is a parabola relationship between the deposition amount of coatings and time.
Preparation of Microsized Monodisperse Silica Spheres by Hydrolysis of Tetraethoxy Silane
Authors: Wang Guang Hai , Li Ang , Zhang Yue
Published: April 2010

Monodispersed silica spheres have attracted much attention because of their widely applications in the areas of catalysis, adsorption, chromatography packing materials and advanced ceramics. This paper focused on its application as a packing material of function coatings for space applications. Nanosized monodispersed silica spheres can be fabricated by Stöber method. However, microsized monodispersed silica spheres are not easy obtained. In this paper monodispersed silica spheres with the size between 200nm to 2000nm were fabricated by hydrolysis of tetraethoxy silane (TEOS) in isopropyl alcohol solvent and using ammonia as catalyst through multi-step growth method. The influence of silica seed number density and TEOS concentration on monodispersity and size of silica sphere were studied. The result shows that monodispersed silica spheres could be obtained through control the concentration of TEOS and the silica seed number density during every growth step. The diameter of monodispersed silica spheres increased with the steps of growth.
Influence of Solution pH Value on the Preparation of SrTiO3 Thin Films through Self-Assembly of Liquid Precursor Reaction
Authors: Cheng Lei , Tan Guo Qiang , Miao Hong Yan , Wang Yan
Published: April 2010

The experimental makes use of the liquid-phase reaction of self-assembly method, we immerse the functional glass substrates into the precursor solution to prepare SrTiO3 films, which makes (NH4)2TiF6, Sr(NO3)2, H3BO4 as raw materials, then study the growth status of SrTiO3 thin films under different pH values of precursor solution, the morphology and the phase of the films are characterized by OMS, XRD and SEM, it is shown that when the pH value of the precursor solution under 2.0, the SrTiO3 films are unable to grow, when the pH value above 3.0, a white emulsion liquid precursor solution occurred, as a result, SrTiO3 films deposition can’t be achieved. And when the pH value between 2.0 and 3.0(contain both), with the pH value increasing the deposition time of the SrTiO3 films decreases. After annealing treatment at 600°C, we can have a conclusion that under these conditions the phase of the films are pure SrTiO3 films, the surface is smooth and the grains grow uniformly.
Effects of Preparing Conditions on the Performances of Nano La(S,C)-TiO2 Films
Authors: Xu Ke Jing , Xi Jin Tao
Published: April 2010

The La (S,C)-TiO2 oriented films with honeycomb ceramic wafers as carriers were prepared by template hydrothermal synthesis. The effects of the hydrothermal reaction temperature and the amount of template agents on the performances of nano-TiO2 films were studied. The films were characterized on the XRD, BET, EDS and SEM. The results showed that the TiO2 films with anatase phase were obtained when hydrothermal reaction temperature was 150 °C and the reaction time was 10h, and the oriented films were obtained when the molar ratio of PEO-PPO-PEO（P-123）to Ti was 0.03. The data also revealed that the specific surface area of particles in the film increased from 148 m2/g to 240 m2/g, and the oriented film could fully decompose methyl orange in water for 3 h.
Characteristics of TiB2 Coating on the Surface of Copper Alloy Prepared by Vibrating Electrospark Deposition
Authors: Luo Cheng , Dong Shi Jie , Xiong Xiang
Published: April 2010

Functional TiB2 coating was prepared onto the surface of Cr-Zr-Cu electrodes by vibrating electrospark deposition in order to extend their service life during resistance spot welding of Zinc coated sheet steels. The microstructure and mechanical properties of the coatings have been characterized by scanning electron microscopy, energy dispersive analysis, X-ray diffraction and micro-hardness tests respectively. The results indicate that cracks appear in the coating due to the tensile stress accumulation and delamination of the coating is related to mismatch in the equivalent valence electron. Cu diffuses obviously from the substrate to the surface of the coating, forming a gradient distribution and making the bonding of the interface between the coating and the substrate an atomic one. TiB2 coating is oxidized during deposition under high temperature of electrosparking. The micro-hardness of the coating is approximately 500HV, which is much bigger than the hardness of the uncoated ones.
Surface Microhardness and Flexural Strength of Colored Zirconia
Authors: Liu Qi , Shao Long Quan , Wen Ning , Deng Bin
Published: April 2010

The surface microhardness and flexural strength of colored zirconia were examined. Two groups of zirconia disks (1mm thick, 20mm in diameter) within 5 disks each were shading with the same coloring liquids IL2 (Vita Classic-scale) when another group of 5 disks measured in no color. The shading time of one group was 3s and that of the other group was prolonged to 30s. The mechanical properties were tested after sintering at 1500°C. Data were evaluated using ANOVA analysis. Disks of shading 30s showed a lower strength 712  53 MPa. The value of 3s was 853  46 MPa. There were no significant difference on microhardness between the two shading time. Prolonged the shading time lowered the biaxial flexural strength of zirconia ceramic, but shading time did no effect on surface microhardness.
Optimization of the Preparation Process of Nano-TiO2/Micro-Cu Composite Particles
Authors: Wang Bin , Cui Hai Ping , Yan Jun , Du Shi Guo
Published: April 2010

Nano-TiO2/micro-Cu composite particles were prepared by hydrolysis of Ti(OBu)4 in abundant acidic aqueous solution and subsequent reflux in the presence of micron size Cu powders. The preparation process was optimized using response surface design with the degradation of TiO2/Cu particles to Methyl orange as target. The particle morphology and composition were characterized by FE-SEM, XPS and XRD. The photon absorption properties of composite particles was investigated by the UV-VIS DRS experiments, and the results show the photoabsorption property of composite particles is intermediate between TiO2 particles and Cu powders, showing cooperative effect by the combination of oxide semiconductor particles with metal substrate.
Fabrication of Fe-Based Al2O3-TiC Ceramic /Steel Composite by Self-Propagation High-Temperature Synthesis
Authors: Zhai Chuan Xin , Li Yan , Wang Xin Yang , Xu Liu Jie , Wei Shi Zhong
Published: April 2010

The Fe-Based Al2O3-TiC Ceramic Composite was fabricated by combining the methods of Self-propagating High-temperature Synthesis with casting. The microstructures of ceramic layer and interface were characterized via SEM, EDS and X-ray diffraction. The Results show that the microstructure of ceramic layer is dense, and the in-situ Al2O3 and TiC particles with size of 1-2 μm are distributed on the ferrite matrix. The hardness of compact ceramic layer reaches 48HRC, and it has graded distribution from ceramic layer to the ferrite matrix. The composite interface between ceramic and matrix is compact, and takes on flexuous. The composite material bonds in a metallographic manner, with high bonding strength.
Ab Initio Study of Water Clusters Adsorption on Graphite Surface
Authors: Fan Bing Bing , Wang Hai Long , Guan Li , Chen De Liang , Zhang Rui
Published: April 2010

Using the density functional theory method, we have characterized the geometrical structures and adsorption energy of water clusters adsorption on graphite surface. When one water molecule inter- acts with graphite surface, one of the H-O bonds formed hydrogen-bond with carbon atom in graphite sheet; in the two water molecules structure, the linear dimmer nearly parallel to the graphite surface, and also formed the hydrogen-bond; when the number of water molecules increased to six, all the H-O bond that point to the graphite surface has formed Hydrogen-bond with it. The binding energy of the water clusters with a graphite surface depends only on the number of water molecules that form hydrogen bond.
Characteristic of Microarc Oxidized Coatings on Titanium Alloy Formed in Electrolytes Containing Aluminate and ZrO2 Particles
Authors: Zhong Ye Sheng , He Xiao Dong , Yu Jia , Shi Li Ping
Published: April 2010

Microarc oxidation (MAO) is a relatively convenient and effective technique to deposit ceramic coatings on the surfaces of Al, Ti, Mg and their alloys. This technique can introduce various desired elements into titania-based coatings and produce various functional coatings with a porous structure. Microarc oxidized (MAO) TiO2-based coatings on titanium alloy were formed in electrolytes containing aluminate and ZrO2 particles. The phase composition of the samples was analyzed by glance-angle X-ray diffraction and the surface morphologies of the samples were observed by a scanning electron microscopy (SEM). In addition, the element concentrations on the surfaces of the samples were measured by an energy dispersive X-ray spectrometer. The experiment results indicated that: MAO coatings, which are porous structures and exhibit good interfacial bonding to the substrate, may possess specific surface structures such as crystal phase, non-equilibrium solid and complex mixed-compounds since complex plasma physical and chemical reactions.
Structure and Property of Micro Arc Oxidation Ceramic Coatings on Al Alloy in K2ZrF6 Solution
Authors: Wu Zhen Dong , Yao Zhong Wen , Jia Fang Zhou , Jiang Zhao Hua
Published: April 2010

The coatings containing zirconia were produced on LY12 Aluminium alloy by micro-arc oxidation in K2ZrF6 and NaH2PO2 solution. The composition, structure, hardness, friction and wear resistance and corrosion resistance of the coating were studied by XRD, SEM, EDS, ball-on-disk friction tester and electrochemical analyzer, respectively. The results show that coating was composed of m-ZrO2 and t-ZrO2. There were a large amount of Zr and O and a little Al, P and K in the coating. The thickness of coating prepared for 3h was 168μm and the maximum value of the hardness was up to 16.75GPa. The friction and wear resistance and corrosion resistance were improved, compared with the LY12 aluminium alloy substrate.
Preparation of Ti(C,N)-Based Cermets
Authors: Gu Xing Yong , Lv Shu Zhen , Chen Yun Xia , Xu Hai Yang
Published: April 2010

Ti(C,N) solid solution were prepared at 1450°C and 1atm nitrogen pressure and the effect of the ways of adding nitrogen on the mechanical properties and microstructures of Ti(C,N)-based cermets were investigated. XRD and FESEM were employed to characterize the as-prepared Ti(C,N)-based cermets. Vickers hardness and fracture toughness were also tested. As a result, The mechanical properties of Ti(C,N)-based cermets prepared by Ti(C,N) solid solution is better than that directly prepared by TiN. The former shows the homogeneous microstructures, the same particle size of hard phases, low porosity, and good sintering character, due to the significant reducing of denitrification when using Ti(C,N) solid solution to introduce nitrogen element. The cross-section SEM images reveal that the dominant fracture behavior of Ti(C,N)-based cermets is transgranular fracture, also including intergranular rupture. The presence of Ni3Ti brittle phase will affect the fracture toughness property of the as-prepared cermets. The more the content of Ni3Ti is, the lower KIC is.
Coating Evaluation Using Ultrasonic Wave Technology
Authors: Chang Jun Jie , Wang Xing Guo , Shan Ying Chun , Xu Jiu Jun
Published: April 2010

The capability of Rayleigh wave to be used as a tool for the evaluation of CVD DLC coating layer has been presented in this paper. One uncoated specimen and two CVD DLC coated specimen has been used. The dispersion curves of group velocity of leaky Rayleigh wave were measured. The dispersion curve of uncoated specimen shows that the group velocities were same at different frequencies, as there is no coating layer affecting the group velocities at different frequencies. There are distinct different between ‘sound’ specimen and ‘bad bonding’ specimen as the ‘bad bonding’ specimen show unevenness on its dispersion curve.
Enhancement in Bioactivity of Titanium Substrate with Composite Thin Films
Authors: Gao Fei , Xiao Fan , Zhang Zhi Xian
Published: April 2010

Nanometer TiO2 microcapsule has potential applications in biochemistry, drug Controlled Release, and catalyst. Meanwhile, Ultraviolet (UV) light-induced bioactivity of titanium substrates is attracting more and more attention nowadays. Composite thin films formed by Nano-TiO2 microcapsule prepared by a novel and versatile technique of layer-by-layer (L-b-L) deposition using the Nanometer latex particles of Polystyrene (PS) as the template together with TiO2 films synthesized at low temperature by the hydrolysis of titanium chloride (TiCl4) precursor was successfully deposited on the different titanium substrates after the template was removed. Thus great expectation was placed on whether UV radiation can enhance the bioactivity of the titanium substrates after the composite thin films being deposited on its surface. The apatite-forming ability was evaluated after the UV-irradiated implants being soaked in simulated body fluid (SBF) within different hours by Scanning electron microscopy (SEM), XRD. The vitro results indicated that UV radiation was favored to formation of apatite on titanium substrates. Besides, the effect of different UV- irradiation time on apatite-forming was different.
Influence of Different Ceric Oxide and Ferric Oxide Content on the Color of Alumina-Glass-Composites Restoration
Authors: Zhao Chun Peng , Lu Huai Xiu , Shao Long Quan , Deng Bin , Zhang Wei Wei , Yi Yuan Fu , Dong Li Min , Tian Jie Mo , Wen Ning
Published: April 2010

This study aims to investigate the effects of ceric oxide and ferric oxide on the color of alumina-glass-composite (AGC). Uncolored glass and colored glass powder with 4% ceric oxide and 0.5% ferric oxide were fabricated. Primary mixture powder were made by mixing the two colored glass powder with 0.1g interval, and then 81 kinds of colored mixture powder were gained by mixing uncolored powder with the primary mixture powder. Molten glass was infiltrated into presintered alumina blocks. The colored AGC and VITAPAN-3D-MASTER shade guide were measured with spectrophotometer. Experiment results showed that the Yxy value of VITAPAN-3D-MASTER shade guide distributed from (185,0.378,0.340) to (121,0.443,0.341) and the Yxy value of colored AGC distributed from (227,0.352,0.343) to (102,0.489,0.364). There were 37 kinds of samples in the color range of shade guide. The color range of 81 kinds of AGC covered that of the VITAPAN-3D-MASTER shade guide.
Mineralization of Magnetite Induced by Chitosan Hydrogel
Authors: Wang Yong Liang , Li Bao Qiang , Zhou Yu , Jia De Chang
Published: April 2010

Mineralization is a powerful approach for fine inorganic minerals and organic/inorganic complexs with novel structure. The morphology of composites show the mineralized magnetite dispersed in chitosan hydrogel uniformly. The reason for uniform dispersion might be that the chitosan hydrogel restricted the moving ability of iron ions and the iron ions can only move to the nearest crystal nucleus. The magnetite content of magnetite/chitosan composite was approximately 12.6%. The mineralized magnetite have a significant interaction with chitosan which induced the magnetite/chitosan composite has a higher decomposition temperature than chitosan. After decomposition, the magnetite transformed into γ-Fe2O3 and α-Fe2O3, and a significant crystal growth happened.
Behavior of hBMSC on Nano Hydroxyapatite Surface
Authors: Wu Gang , Wang Ying Jun , Wei Kun
Published: April 2010

The bioactivity of HA has been tested by its osteoconduction ability in vivo. Nano HA has higher specific surface area and was presumed to have high bioactivity. In this paper, nano needle HA was synthesized by the microemulsion method. The properties of such nano materials were analyzed by the XRD and TEM. The impact of the nano HA on the expression of two hBMSCs’ genes, inhibitor differentiation 2 and ostopontin, and the ALP activity was researched in this paper.
Effect of Doped Traditional Chinese Medicine Drynariae Rhizoma on the Porcine Bone Hydroxyapatite and Chitosan Porous Scaffold
Authors: Li Mu Qin , Wang Jing Yan , Ma Chen
Published: April 2010

Chinese medicine Drynariae Rhizoma extract (DR) was introduced into porcine bone hydroxyapatite (PBHA) and chitosan (CS) for the preparation of scaffold by the Vacuum freeze drying method in order to accelerate bone growth and weak bone adhesion in the early healing stage of scaffold. The microscopic morphology and composition of the scaffolds were analyzed by SEM, XRD and IR. Compressive strength of the scaffold and the porosity was tested. Biological activity of the scaffolds was studied by immersed in Simulated Body Fluid (SBF). The scaffolds were a high porosity of 80% and compressive strength of 1.2MPa. Carbonate containing bone-like HA was formed on the surface of the scaffold after immersion in SBF, showing that the scaffold materials have good bone-like apatite forming ability. The scaffolds of DR -PBHA- CS have good physical and chemical properties, good biological activity and low price.
Calcium and Phosphate Biocoatings on Magnesium Alloy Fabricated by Micro-Arc Oxidation
Authors: Ma Chen , Zhang Xiang Yu , Qu Li Jie , Li Mu Qin
Published: April 2010

Calcium phosphate biocoatings were fabricated on the surface of magnesium alloy by micro-arc oxidation (MAO) technique. The properties of biocoatings related with MAO technics parameters and the electrolyte constitute. The surface morphology, constitute and friction coefficient were studied by SEM XRD and fret test machine. The results indicated that the optimum electrolyte was CaCO3-Na3PO4 contained 20g/L phosphate ions and 1.5 Ca/P ratio, and the optimum technics parameters was 350V oxidation voltage for10min, 500HZ pulse frequency and 1:10 in duty cycle. The main phase constitutes of the porous biocoatings contained were Mg, MgO, Mg3(PO4)2 and CaNaPO4. The anode polarization potential of the coating was -1.36V and enhanced about 0.29V compared with that of magnesium alloy substrate, which indicated that the biocoatings had better corrosion resistant properties. The friction coefficient of the biocoatings was 0.23 and decreased 0.15 compared with that of magnesium alloy substrate, which indicated that the biocoatings had better wear resistant properties. The biocoatings could induce hydroxyapatite to form on its surface after soaked in body fluid, which showed that the composite coatings owned good bioactivity.
Remineralized Evaluation of Nano- Hydroxyapatite to Artificial Caries
Authors: Lv Kui Long , Yuan Hai Wen , Meng Xiang Cai , Li Xing Yi
Published: April 2010

The aim of this study is to describe the remineralization effect of the nano-HA on artificial caries. The artificial dental caries are made by using sour solution, and constructing an artificial mouth' plaque culture system in vitro respectively. The scanning electron microscope (SEM) and the optical microscope are used to observe the surface of enamel specimens. The effect of remineralization is assessed with the polarized light microscopy (PLM) and the confocal laser scanning microscope (CLSM) by measuring three lesion parameters (area, total and average fluorescence). The SEM analysis shows that the cavities and defects of enamel surface are decreased and many mineral salts are sedimentated, which indicate that the nano-HA could promote remineralization for the demineralized enamel. The inhibitory effect of the spherical nano-HA on dental caries is detected in the artificial mouth test. The CLSM shows that demineralization of enamel is reduced by adding the spherical nano-HA in artificial mouth. The results show that the spherical nano HA have a remineralization effect on the artificial dental caries dramatically, and can prevent and decrease caries.
Microwave Pyrolysis Chemical Vapor Infiltration of Carbon: Textural Changes
Authors: Zou Ji Zhao , Zeng Xie Rong , Niu Ben
Published: April 2010

Carbon/Carbon composites were fabricated by microwave pyrolysis chemical vapor infiltration. The carbon fiber felts (the bulk density ~0.2 g/cm3) were infiltrated from methane at temperature of 1075°C, 1100°C, 1125°C and 1150°C, methane partial pressure ranging from 5KPa to 15KPa, and gas residence times of 0.05s ,0.1s, 0.15s and 0.2s. The effect of residence time, deposition temperature and partial pressure of source gas on the textures was studied by polarized-light microscopy. The results show that the anisotropy of texture is better when the parameter is higher; and rough layer texture can be fabricated easily by microwave pyrolysis chemical vapor infiltration.
Mechanism Analysis of Synthesizing Fe-Si3N4 by Flash-Combusting FeSi75
Authors: Chen Jun Hong , Li Bin , Yu Ling Yan , Song Wen
Published: April 2010

It is necessary to know the synthesis mechanism of Fe-Si3N4 by flash-combusting FeSi75 in order to control the phase composition and microstructure of Fe-Si3N4 composites. In this paper, Fe-Si3N4 and starting material FeSi75 were analyzed with XRD, SEM and EDS. The results show that Fe-Si3N4 synthesized by flash-combusting FeSi75 (≤0.074 mm) is composed of β-Si3N4, α-Si3N4, FexSi, and SiO2, in which β-Si3N4 and α-Si3N4 are from the nitridation of metal silicon and part of the silicon in ξ phase while FexSi is from the nitridation of ξ phase; during the nitridation of ξ phase, Si content declines gradually, when Fe: Si is close to 3, the nitriding reaction tends to balance; the loose accumulation of nitriding products results in the slow heat release, which makes α-Si3N4 transform to β-Si3N4 and β-Si3N4 grow further to form rod-like β-Si3N4 crystals of high slenderness ratios; the rapid quenching of nitriding products helps to keep the proportion between α-Si3N4 and β-Si3N4 small particles, and to reduce the crystallization of rod-like β-Si3N4; The grain size and distribution of FexSi in Fe-Si3N4 are related to the particle size and distribution of ξ phase in the starting material.
A Technique for the Preparation of Porous Ceramic Materials by Gelcasting Method
Authors: Huang Hao , Cheng Da Ming , Tong Jian Feng , Li Bao Wei , Wang Ling
Published: April 2010

A technique for the preparation of porous ceramic materials by gelcasting mothod is studied using a water-soluble epoxy resin combined with a amine hardener. The increase in the volume and rheological behavior of slurry , TGA and DSC of the green bodies are investigated. The influence of solid content on the relative density, the cell size distribution and the compressive strenghth is studied. The experimental results show that in the measurable shear rate range the rheology of slurry exhibt a shear thinning behavior, the relative density increase with the solid content, with the decrease of the relative densities the cell size increase. The compressive strength increased exponentially with the increase relative density, and the exponent, m, is 1.094.
Fabrication, Structure and Properties of Porous SiC Ceramics with High Porosity and High Strength
Authors: Wang Shao Feng , Wang Chang An , Sun Jia Lin , Zhou Li Zhong , Huang Yong
Published: April 2010

Porous SiC ceramics with high porosity and high strength were fabricated by gelcasting, with tert-butyl alcohol (TBA) as solvent, acrylamide (AM) as monomer, and in-situ reaction bonding with a-Al2O3 as sintering additive. SiC suspension with 10 vol% solid loading was successfully solidified by gel-casting to form high strength green body. The results showed that the compressive strength of the porous SiC ceramics increased with sintering temperature from 1300 to 1450°C, but porosity had little change, due to formation of more volume of cristobalite and mullite phases on the surface of SiC grains, accompanied by a large volume expansion effect. Very narrow single-peak distributions with about 2 mm median pore diameter could be found for the porous SiC ceramics. The porosity and compressive strength of the porous SiC ceramics sintered at 1450°C were 71.21 % and 12.14 MPa, respectively.
Porous Silicon Nitride Microwave Transparent Material with Compounded Component Pore Former
Authors: Gao Fang , Wang Chong Hai , Li Ling , Chen Da Qian , Zhai Ping , Wei Qi Hong , Wang Hong Sheng
Published: April 2010

It is an effective way to decrease dielectric constant of microwave transparent materials by improving porosity rate. Network -Si3N4 porous transparent materials were prepared by gas pressure sintering (GPS) with Y2O3 additions. Porosity rate of silicon nitride using pore former with different content starch, polytetrafluoroethylene (PTEE) powder respectively and their compounded component were discussed in this paper. It is concluded that porosity rate can be improved by all the three, starch is most favorable to improve porosity but great volume rebound after cold iso-static pressing were happened and easily lead to crack of green body. Method of pore-making by step on principle of pore formers discharging in different temperature range used to get high strength and porosity green body. Series of porous silicon nitride microwave transparent materials were prepared with porosity rate from 48% to 67%, bending strength from 162MPa to 59MPa and dielectric constant from 3.41 to 2.37.
Effect of Silicon Addition on the Properties and Microstructure of Corundum-Mullite Refractory
Authors: Wei Xiao Hui , Wang Yan Jun , Li Hong Xia , Sun Jia Lin
Published: April 2010

The influence of silicon addition on the microstructure and properties of corundum-mullite refractory was studied. Results show that Si addition as raw material of the matrix can accelerate mullite crystal formation. The oxidation of Si leads to nucleation of mullite via liquid phase and gas phase. The network microstructure is formed by tiny mullite crystals with few glass phase. So it enhances obviously the high temperature strength of sintered corundum-mullite refractory.
Properties of Ceramic Filter Material Made of Coal Fly Ash and its Application in Chromium(VI) Removal
Authors: Jing Zhao Qian , Xue Hong Qin , Lin Shao Hua , Wang Zheng
Published: April 2010

Ceramic filter material was developed mainly with coal fly ash and used as an absorbent for Cr(VI) removal. This material was characterized through physico-chemical analysis with scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS) and mercury porosimeter. Then static adsorption experiment was carried out to study adsorption characteristics of Cr(VI) on this filter material. SEM patterns indicated this material had enormous specific surface area and high porosity. EDS results showed this material was mainly composed of O, Si, C, Al, Mg, Fe, Ca and K in various compounds. Total pore area and porosity above 1.5 nm were 66.8 m2/g and 60.1% respectively. The main parameters affecting Cr(VI) adsorption were dosage and contact time. 200 g/l dosage of this filter material could remove more than 90% of Cr(VI) to solution with 20 mg/l initial concentration. Adsorption isotherm accorded with both Langmuir and Freundlich model. The study proved this ceramic filter material was a good adsorbent with high adsorption capacity to Cr(VI).