bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Characterization of Poly(D,L-Lactide)-Based Shape Memory Polymers
Authors: Li Yong Gang , Wang Yuan Liang , Luo Yan Feng
Published: September 2009

Biodegradable novel poly(D,L-lactide)-based shape memory polymers (SMPs) were prepared from poly(D,L-lactide) (PDLLA) Diols, hexamethylene diisocyanate(HDI) and butanediamine(BDA) via two steps polymerization reaction. Its thermal, mechanical properties and shape-memory behaviors were investigated by means of differential scanning calorimetry, stress-strain measurements and bending test. The glass transition temperature of the SMPs changes with composition from 38 to 45°C which close to body temperature in a predictable manner. These type SMPs can achieve the high modulus and tensile strength, and their elongation at break can be greater than 500% at lower hard segment content. All SMPs display excellent shape-memory properties. When a deformation temperature 20°C above Tg was chosen, the ratio of the shape-memory fixation approximately 100%, and the recovery ratio was 95-100%. Meanwhile, the recovery time is relevant to the recovery temperature, the recovery time decrease with increasing the recovery temperature. By adjusting the composition of SMPs, the recovery temperature could be adjusted to the neighborhood of the body temperature and it can be designed as potential biomaterials for use in biomedical fields.
Virtual Experimental Studies on Carbon Fiber Smart Materials Resistivity Tomography
Authors: Dai Ya Wen , Li Zhuo Qiu , Zhang Xiao Yu , Zhu Si Rong
Published: September 2009

With the emergence of large-size complex structures, conventional discrete sensors can’t meet the requirement of structure health monitoring because they can only sense the strain in a single direction. In this paper, based on sensing and covering properties of carbon fiber smart material (CFSM), an idea of a sensitive layer placed on the structure surface was proposed. By setting finite electrodes on the edge of the sensitive layer, the stress field of tested structure is transformed to electric field which is apt to be tested, and with resistivity tomography technology (ERT), field(global) monitoring on civil engineering structure can be realized. To avoid impact resulting from measuring errors caused by misc factors in experiment, CFSM ERT system was utilized in virtual experiments. Virtual Experiments were conducted on ANSYS finite element software aided by its excellent abilities in coupled field analysis. The virtual experiments included two cases: circular plate simply supported at its perimeter under single loading of different values in the center, and circular plate simply supported at its perimeter under multipoint loading in different positions. In the virtual experiments current incentive in adjacent electrodes and voltage measurement in other adjacent electrodes were implemented, and the measured voltage data was transmitted to the ERT system to obtain the contour plot of resistivity distribution. It indicates that for the single loaded CFSM virtual experiment with tensile strain, its resistivity is increased with the load increase. Compared with 1st and 2nd principal strain distribution in structure tested area, resistivity distribution will qualitatively reflect force field of structure. In multipoint loaded CFSM virtual experiment with compress strain, resistivity descends. Compared with 3rd and 2nd principal strain distribution in structure tested area, low resistivity area just locates at area of biggest strain. Based on virtual experiment, efficiency of CFSM ERT system is demonstrated, greatly supporting the consequent practical application.
Synthesis and Electromagnetic Properties of Polyaniline Nanofibers Using Polyglycol as ‘Soft’ Template in the Aqueous Ethanol
Authors: Liao Yuan , Qi Shu Hua , Wang Dong Hong , Wu You Ming
Published: September 2009

In this paper Polyglycol (PG) was used as ‘soft’ template to induce the polymerization of aniline in aqueous ethanol and hence control both the nucleation and growth of polyaniline (PANI) nanofibers. The products were characterized by Transmission electro microscope (TEM) and X-ray diffraction (XRD) techniques. TEM photos showed that the diameter of PANI nanofibers synthesized in pure water is 100nm while that of PANI nanofibers synthesized in aqueous ethanol is 50nm. It revealed that the volume fraction of ethanol showed really important effect on the morphological parameters of the PANI nanofibers. The X-ray diffraction patterns of the PANI nanofibers showed high crystallinity. Moreover, the resulting PANI nanofibers exhibited an unusual electromagnetic loss at the microwave frequency (f = 8.2~12.4 GHz) . Compared with 1.79, the highest electrical loss, tanδe, of the microparticles PANI at 8.47 GHz and 0.72, the highest magnetic loss, tanδm at 10.93 GHz, it was noted that the highest electrical loss, tanδe, of PANI nanofibers reached 3.26 at 10.4 GHz, and the highest magnetic loss, tanδm, was 2.85 at 9.35 GHz. It might arise from order arrangement of polaron as charge carrier caused by nanofibers morphology and can be used for the potential application as microwave absorbing materials.
Nanostructure of 45# Carbon Steel by High Current Pulsed Electron Beam
Authors: Zou Hui , Jing H.R. , Hao Sheng Zhi , Dong Chuang
Published: September 2009

When high current pulsed electron beam (HCPEB) transferring its energy into a very thin surface layer within a short pulse time, super fast processes such as heating, melting, evaporation and consequent solidification, as well as dynamic stress induced may impart the surface layer with improved properties. In this paper, HCPEB modification of 45# carbon steel with working parameters of electron energy 25 kV, pulse duration 3.5µs, and energy density 4 J/cm2 was investigated. The microstructures of modified surface were analyzed by scanning electron microscope (SEM) of type JSM 5310 and transmission electron microscope (TEM) of type H-800. It is found that the modified surface layer can be divided into three zones: the white layer or melted layer of depth 3 to10µm, the heat and stress effecting zone 10 µm below and about 250 µm, then matrix, where a nanostructure and/or amorphous layer formed in the near-surface region. It is proved that the whole treatment process is not complex and cost-effective, and has a substantial potential to be applied in industries.
Mechanical Properties of Dental Nanocomposites Reinforced with Polyhedral Oligomeric Silsesquioxane(POSS)
Authors: Wu Xiao Rong , Xie Wei Li , Sun Yi , Sun Shou Hua
Published: September 2009

The objective of this study was to incorporate POSS-MA into the polymeric matrix to develop a new kind of nanocomposite. The effect of different weight percentage of POSS incorporated into the matrix on the mechanical properties was also evaluated. Infrared spectroscopic technique and X-ray diffraction were used to characterize their microstructures and double bond conversion. With only 2wt% POSS added, the nanocomposite’s flexural strength increased 15%, compressive strength increased 12%, hardness increased 15% and uncommonly, even the toughness of resins obviously increased. With 5wt% POSS polymerized, compressive strength increased from 192MPa to 251MPa and compressive modulus increased from 3.93GPa to 6.62GPa, but flexure strength began to decline from 87MPa to 75MPa. The nanocomposites incorporated with POSS showed greatly improved mechanical properties, and increased wear resistance and service life. The mechanism of reinforcement was also discussed.
Improved Preparation Technology of Urea Formaldehyde Microcapsules Used in Electrophoretic Display
Authors: Chen Shu Hui , Wang Shi Rong , Bian Shu Guang , Li Xiang Gao
Published: September 2009

Improved two step in-situ polymerization was applied in the preparation of urea- formaldehyde microcapsules used in microencapsulated electrophoretic display. The dispersion liquid which nano particles of titanium dioxide and carbon black dispersed in tetrachloroethylene was used as the electrophoretic liquid, and the electrophoresis microcapsules was prepared by urea-formaldehyde system. Melamine was used to modify the urea-formaldehyde microcapsules. The effect of different mole rates of urea and melamine to the surface morphology, mechanical strength, and sphericity of the microcapsules were studied. Electrophoretic performance of particles in melamine-urea-formaldehyde (MUF) microcapsules and urea-formaldehyde (UF) microcapsules were contrasted under the same condition. The results showed that as adding melamine in urea-formaldehyde, the time used to prepare microcapsules was shorter, and microcapsules were not easy aggregation during long time storage. When the mole rates of melamine and urea were from 2:8 to 5:5, the microcapsules with smoother surface (Fig.1), stronger mechanical strength and higher transmittance were obtained. Electrophoretic behaviors of particles in MUF (melamine and urea was 2:8 in mole rate) and UF microcapsules were tested under the same condition, respectively. It was shown that particles in MUF microcapsules could be seen significantly moving at the electric field of 10 V/mm, and the response time of these particles was 500 ms at the electric field of 20 V/mm，and it was shorter than 200 ms at the 50 V/mm electric field (Fig.2). On the contrast, the response time of particles in UF microcapsules was greater than 10 s at the electric field of 20 V/mm.
In Vivo Biocompatibility Studies of Nano TiO2 Materials
Authors: Han Wei , Wang Yue Dan , Zheng Yu Feng
Published: September 2009

TiO2 nanomaterials with different dimensions(zero and one), sizes(20nm, 50nm and 100nm in diameter) and crystal structures(100% rutile, 100% anatase and combination of 20% rutile and 80% anatase) were confected to suspensions and ointment with varied concentrations and evaluated in animal model (Balb-c mouse). These mouse were divided into various groups randomly, with suspension intraperitoneally injected or ointment transdermally daubed. Heart, lung, liver and kidney were collected and prepared to HE sample after one week. Spectrophotometry was applied to study total antioxide capability and catalase activity of blood and tissues. It has been shown that all TiO2 nanomaterial groups had no effect on lives’ morphology and oxidative stress, with no obvious histopathological changes observed in heart, lung, liver and kidney, and these tissues presented no vacuolar degeneration, necrosis edema, engorgement and inflammation.
Microstructure and Hardness Characterization of a NiCr/Cr3C2 Coating by High-Velocity Oxy-Fuel Thermal Spraying
Authors: Wu Yu Ping , Li Gai Ye
Published: September 2009

A NiCr/Cr3C2 composite coating with a thickness of approximately 200 m was deposited onto 1Cr18Ni9Ti stainless steel substrate by high-velocity oxy-fuel (HVOF) thermal spraying. Microstructure of the coating was characterized using X-ray diffraction(XRD), scanning electron microscopy(SEM) and transmission electron microscopy (TEM). The coating comprised a NiCr matrix and two types of carbides. The NiCr matrix was composed of an amorphous phase and nanocrystalline grain with a size of 10–50 nm. The microhardness of the coating was found to be 1200Hv, which is significantly greater than that of the stainless steel (1Cr18Ni9Ti) substrate (285 Hv).
Preparation of Phosphorylated Chitosan/ Chitosan/ Hydroxyapatite Composites by Co-Precipitation Method
Authors: Li Bin , Wang Xin Bo , Ma Jin Huan , Huang Long Nan
Published: September 2009

In this work, the PCS/CS/HA composites with different weight ratios were prepared through a co-precipitation method. The properties of these composites were characterized by means of the XRD, the IR, the SEM and the bending strength test. The value of bending strength of the PCS/CS/ HA composite with a weight ratio of 10/30/60 was measured about 34.93 MPa which is 1.6 times high of the cancellous bone. The composite is appropriate to be used as materials for bone tissue engineering.
Rapid Synthesis of Eu2Zr2O7 Nanocrystals via Salt-Assistant Combustion Method
Authors: Tong Yu Ping , Li Chang Yong , Zhao Shun Bo
Published: September 2009

Eu2Zr2O7 nanocrystals with cubic structure were successfully synthesized by salt-assistant combustion method. The Eu2Zr2O7 nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Emission/ excitation spectra. The effect of thermal treatment temperature on the crystal size of nanocrystals was studied. The results indicated that Eu2Zr2O7 nanocrystals obtained by this method were well-dispersed and uniform in particle size distribution with average size of 20 nm. By comparison, it was found that the introduction of KCl in the solution combustion reaction process can effectively prevent nanocrystallites from sintering and forming inseparable three-dimensional network, and result in the formation of well-dispersed nanoparticles. The method provides a convenient, low-cost and nontoxic route for the synthesis of nanostructures of oxide materials. Moreover, the strong fluorescent property of the Eu2Zr2O7 nanocrystals obtained by salt-assistant combustion method at 385 nm upon excitation was measured at room temperature. The results showed that Eu2Zr2O7 nanocrystals obtained by salt-assistant combustion method put up excellent fluorescent properties.
Microstructure of Ultrasonic-Electrodepositing Nano-Silver Coatings
Authors: Gong Ting , Bai Xiao Jun , Xiang Xiong Zhi , Ma Song Feng , Ling Cai Yun , Zhang Guo Tao
Published: September 2009

In this paper, A kind of ideal non-cyanide silver deposits was obtained by joining the ultrasonic. ultrasonic frequency of 28KHz, power increased from 0-500W, XRD tests show:with the increasing in electric power deposition, silver coating (111) and (200) crystal plane orientation significantly improved, and (220) crystal plane orientation declined . With the ultrasonic power increased, silver deposition current efficiency increased first and then reduced. the grain size refined with the ultrasonic increasing .the corrosion resistance decreased with the ultrasonic increasing.and SEM showed that the grain sizes decreased with the ultrasonic.
Solvothermal Synthesis of Nanostructured Flakes α-Ni(OH)2 Microspheres for Electrochemical Capacitors
Authors: Yu Zhan Jun , Dai Ying , Chen Wen
Published: September 2009

Nanostructured flakes α-Ni(OH)2 microspheres were successfully synthesized by a facile solvothermal method using sodium dodecyl sulfate as a soft template and urea as a hydrolysis-controlling agent. The obtained products were characterized by Thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Electrochemical properties studies were carried out using cyclic voltammetry, galvanostaitc charge/discharge method, respectively. The results exhibited that the α-Ni(OH)2 single electrode had high specific capacitance in KOH electrolyte. A maximum specific capacitance of the α-Ni(OH)2 single electrode was up to 2398F/g in 6M KOH electrolyte concentration with 0 to 0.4V potential at 4mA/cm2 current density. Furthermore, the effects of the heat treatment temperatures on the electrochemical capacitance of the α-Ni(OH)2 electrodes were investigated.
The Application of Nanotechnology/Ultrafining Treatment Technology in the Preparation of Ultrafine Explosives
Authors: Xiong Yan Fei , Yu Jiang , Lin Hao , Li Shi Li
Published: September 2009

At present, the methods of preparing ultrafine explosives are as it follows: mechanical mill method, recrystallization refining method, supercritical fluid method, air stream pulverization method, high-speed impinging method, micro-emulsion method, spray-drying method, direct dilution method, ultrasonic method etc. Although there are so many methods, each one has some inevitable disadvantages. In order to enhance the further research of ultra fine explosives, we mainly place emphasis on the application of recrystallization refining method, supercritical fluid method, jet milling method, high speed impinging method, spray-drying method, ultrasonic method etc.
Laser Cladding NiCrBSi+2%B4C Coating on Ti-6Al-4V
Authors: Fan Xiao Hong , Geng Lin , Xu Bin , Li Jing
Published: September 2009

A process of laser cladding of NiCrBSi+2%B4C powder on Ti–6Al–4V substrate to form a coating was carried out, a good coating without cracks and pores was obtained in the process. The microstructure and component of the coating were examined using SEM and EPMA. The interface between the coating and the substrate was metallurgical, The microstructure of NiCrBSi+2%B4C cladding layer consisted of the Ni-based matrix, and the uniformly dispersed reinforcement phases of TiB2, TiC, etc. The microhardness of the coating was measured using a Vickers hardness tester. The average microhardness of the composite coating was HV1200 HV1400, and it was three times higher than that of Ti-6Al-4V substrate.
Controlled Fabrication of Nanocomposite with Ni Deposition on the Template of SiO2 Particles and its Magnetic Property
Authors: Fu Yu Bin , Zai Xue Rong
Published: September 2009

SiO2 /Ni nanocomposite is directly prepared from the silica particle by a controllable method through electroless metallization, which is different from the sol-gel technique. Its fabrication procedure is as follows: first the formation of ligating monolayer by a silane agent coupling with silica, then, binding Pd catalyst with its ligating group, finally, nano-sized Ni deposition occurs on the template. The metallic Ni particles are uniformly deposited on the silica, and they have a net or chain-like structure, just as the silica particles do. The composite inherent coercivity (iHc), saturated magnetization (MS), and residual magnetization (Mr) are 16.5, 10.0 and 1.00 respectively in the as-plated Ni. The chain-like structure causes stronger static magnetization interactions between Ni particles, resulting in a magnetic crystalline anisotropy and the higher iHc value.
Synthesis of Hydroxyapatite in Microemulsion and its Adsorption Properties for Human Serum Albumin
Authors: Zheng Xian Peng , Liu Yan , Yang Yan Ming , Wei Dong , Xu Yuan Yuan , Wei Qin , Du Bin
Published: September 2009

Hydroxyapatite (HAP) was synthesized in Triton X-100 microemulsion and was characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS). Particle size analysis results showed that the particles has nanometer size, high surface area and loose structure. The prepared HAP had high adsorption capacity to human serum protein and the adsorption of human serum protein on the surface of HAP was confirmed by SEM. The factors which influenced the adsorption capacity such as the acidity, reaction time and the concentration of adsorbent were investigated in detail and the adsorption isothermal was also obtained. The adsorption capacity reduced while the pH value increased, and the adsorption reached equilibrium when shaking time was up to 40 min. The adsorption isotherm could be fitted by the pseudo-Langmuir type. The adsorption of human serum albumin on HAP was investigated, and the influences of adsorption on the conformation of human serum albumin were studied by infrared and ultraviolet spectroscopy. It can be seen from the FT-IR spectra that the intensity of flex vibration of C=O, N-C bonds all weakened. The calculation results of ultraviolet spectrum indicated that the quantity of α spiral structure reduced from 44% to 17.12%.
TiO2 Hollow Spheres Obtained under Autogenic Pressure at Elevated Temperature
Authors: Li Ke Xun , Li Hong Liang , Zhao Jun Hua , Zhu Ying Chun , Zhao Xiu Song
Published: September 2009

Carbon/TiO2 composites were prepared via the reaction under Autogenic Pressure at Elevated Temperature (RAPET) using alkoxides as precursor, and then porous TiO2 hollow spheres were derived after removing the carbon ingredient by calcination at 600°C. The influence of surfactant additives, including the addition ratio and the nature of the surfactants, on the morphology and the structures of the Carbon/TiO2 composites and the derived TiO2 were also studied with scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectrophotoscopy (DRS) and nitrogen adsorption-desorption measurements. The results revealed that the morphology of the products turned to spherical and then fusiform and the structures turned from hollow to solid with the increasing of surfactant additive. The BET surface area of the hollow TiO2 was modified from 12m2/g to 57m2/g after calcinations. The XRD investigation indicates that the phases of the TiO2 in both the carbon/TiO2 composites and the derived TiO2 hollow spheres are anatase.
Effect of Samarium on the Photocatalytic Property of Sm-TiO2/CNFs Composites
Authors: Zhu Li Ying , Yang Xiao Ping , Teng Dong Hua , Yu Yun Hua
Published: September 2009

Composites of Sm doped TiO2 nanoparticles dispersed on carbon nanofibers (Sm-TiO2/CNFs) with different Sm contents were prepared by preoxidation, hydrolyzation and calcination of Sm-TiO2 precursor/PAN nanofibers. The characterizations of SEM, EDX, XPS and XRD showed that the CNFs surface was loaded by Sm-TiO2 nanoparticles with a uniform size of about 10nm, existing as anatase. It was concluded from XPS results that Ti element exist as Ti4+ and Sm doping increased the content of absorbed oxygen in composites. The effect of Sm doping on the photocatalytic activity of the Sm-TiO2/CNFs composite was investigated by the photocatalytic degradation of methyl orange aqueous solution under UV irradiation. It was found that Sm doping could improve the photocatalytic property of Sm-TiO2/CNFs effectively compared with the undoped specimen, and the photocatalytic activity of the Sm-TiO2/CNFs samples enhanced firstly and then reduced with Sm content increasing.
Multi-Functional Nanoscaled Film Deposited on PET Non-Woven by Sputtering
Authors: Di Jian Feng , Du Wen Qin , Yu Fei , Qi Hong Jin
Published: September 2009

In order to prepare a time decay-resistant electromagnetic shielding (ES) fabric with good handle, moisture permeability and antibacterial properties, Cu, Ag, Ag/Cu and Ag/Cu/Ag films were deposited on PET non-woven by sputtering in screening experiment. Considering the post continues processing, this study focuses on discharge parameters optimum for a limited short time. Relationship was studied between deposited rate and ES effectiveness (ESE) for the four metallic films on various substrates. The metal deposit greatly relays on the chemical nature of the substrate and target metal category. The deposited metal rate on metal is larger than that on PET. In comparison with single metallic film, the dB value of multi-metallic film obtained for same time even for more time remarkably dropped. Therefore, an Ag-coated PET no-woven was finally fabricated as the multi-functional fabric with anti-decay ESE. The multi-functional PET no-woven with good handle obtained for 3min. by optimizing other parameters exhibits higher ESE, good anti-bacterial and moisture permeability.
Fabrication and Characterization of Titanium Based Nanotubes
Authors: Song Li Ang , Cao Li Xin , Su Ge , Liu Wei , Liu Hui , Zhu Lin
Published: September 2009

Titanium based nanotubes (8-12nm outer diameter and 4-6nm inner diameter) were successfully fabricated by a simple and cost-effective hydrothermal method. The nanotube-like amorphous phases TNT(Na) and TNT(H) were obtained with different post treatment. The samples were characterized by means of high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), selected area electron diffraction (SAED), energy dispersive X-ray spectrum (EDS) and UV-Vis diffuse reflectance spectroscopy (DRS). The photocatalytic activities of the nanotubes were evaluated using photo-oxidation of methyl orange.
Methane Catalytic Cracking to Make COx Free Hydrogen and Carbons (Nanotubes, Microfibers, Microballs)
Authors: Gao Li Zhen , Zhang Wei Ke , Cornejo Andrew , Chua Hui Tong
Published: September 2009

The catalytic cracking of methane to produce COx free hydrogen and a spectrum of advanced carbon nano materials was studied. Over several genres of catalysts by cracking of undiluted methane we produced hydrogen and highly graphitic carbon nanotubes (single-, thin- and multi-walled), straight microfibers, nano onions over the solid oxides solution, perovskite structured mixed oxides and mesoporous supported catalysts. The influences of reaction temperature on the methane conversion over various catalysts were investigated. The yields of carbon materials were monitored during the cracking running and the results indicated that these series of catalysts are promising for the commercialization of carbon nanotubes, microfibers and microballs.
Monitoring Beam-Column Joint in Concrete Structures Using Piezo-Impedance Sensors
Authors: Divsholi Bahador Sabet , Yang Yao Wen , Bing Li
Published: September 2009

Despite that piezoelectric ceramic lead zirconate titanate (PZT) has been used for structural health monitoring (SHM) in various engineering systems, limited work has been conducted on real size concrete structures. Beam-column connections are critical regions in reinforced concrete (RC) moment-resisting frame structures. The vulnerability of RC beam-column joints has been identified from structural damage investigations over the past decades, especially in the area of earthquake engineering. In the context of a terrorist bomb attack, the beam-column joints are very vulnerable, especially when the perimeter columns lose their load carrying capacity due to damage and the beam-column joints become one of the crucial load transfer mechanism of the structural frame. To avoid catastrophic failures, it is important to monitor beam-column joints under existing gravitational loads. In this paper, an experiment is carried out on four real size concrete frame structures with different detailing subjected to gradually increased loads. A number of PZT sensors are bonded to the frame structure to acquire PZT electro-mechanical (EM) admittance signature. The structural mechanical impedance (SMI) is extracted from the PZT EM admittance signature and its sensitivity is compared with that of the EM admittance. The relations between the damage index and the loading step and tip deflection of the concrete structure are obtained. Finally the sensitivity of the PZT sensors in detection of the critical loading level is discussed. The results show that the PZT sensors are capable of monitoring the integrity and behavior of the real size concrete structures.
Facile Synthesis of ZnO Nanorod and Nanosheet
Authors: Li Chang Jiang , Yin Yan Sheng , Zhu Hai Tao
Published: September 2009

ZnO nanorods, ZnO thick nanosheets and ZnO thin nanosheets can be facilely synthesized at low temperature using Zn(CH3COO)2•2H2O, Zn(NO3)2•6H2O and ZnSO4•7H2O as zinc resources, respectively. In the novel synthesis process, the precursors were firstly prepared using the reaction of zincate and NaOH in ethanol/water mixed medium. Then ZnO nanorods and ZnO nanosheets can be obtained by calcined procuesors at 300°C. The method is simple and low cost and expected to be applied in industry in the future. In addition, the mixed medium could be recycled by distillation process. The kinds of zinc resources and reaction temperature have a noticeable effect on the morphology of the ZnO particles produced.
Structural Parameters Identification Using PZT Sensors and Genetic Algorithms
Authors: Yang Yao Wen , Miao Ai Wei
Published: September 2009

Piezoelectric ceramic lead zirconate titanate (PZT) based electro-mechanical impedance (EMI) technique for structural health monitoring (SHM) has been successfully applied to various engineering systems [1-5]. In the traditional EMI method, statistical analysis methods such as root mean square deviation indices of the PZT electromechanical (EM) admittance are used as damage indicator, which is difficult to specify the effect of damage on structural properties. This paper proposes to use the genetic algorithms (GAs) to identify the structural parameters according to the changes in the PZT admittance signature. The basic principle is that structural damage, especially local damage, is typically related to changes in the structural physical parameters. Therefore, to recognize the changes of structural parameters is an effective way to assess the structural damage. Towards this goal, a model of driven point PZT EM admittance is established. In this model, the dynamic behavior of the structure is represented by a multiple degree of freedom (DOF) system. The EM admittance is formulated as a function of excitation frequency and the unknown structural parameters, i.e., the mass, stiffness and the damping coefficient of many single DOF elements. Using the GAs, the optimal values of structural parameters in the model can be back-calculated such that the EM admittance matches the target value. In practice, the target admittance is measured from experiments. In this paper, we use the calculated one as the target. For damage assessment, these optimal values obtained before and after the appearance of structural damage can be compared to study the effects of damage on the structural properties, which are specified to be stiffness and damping in this study. Furthermore, the identified structural parameters could be used to predict the remaining loading capacity of the structure, which serves the purpose for damage prognosis.
Effect of Sputtering Input Power of Co on Structure and Magnetic Properties of Fe-Co-N Thin Films
Authors: Wang Xin , Jia Hui , Zheng Wei Tao , Xu Wei , Long Bei Hong
Published: September 2009

Fe-Co-N thin films with various Co content were synthesized on Si (111) substrate using facing-target magnetron sputtering by changing sputtering input power on Co target. During deposition, the input power on Fe target was kept at 160 W. The composition, structure, and magnetic properties were examined by X-ray photoelectron spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and superconducting quantum interference device. XRD and TEM investigations showed that at lower input power of 11.2 W on Co target, the phases in the film were -(Fe,Co)4N and Co3N. Increasing sputtering input power, the content of Co in the film increased. At input power of 14 W, film contained -(Fe,Co)8N phase was produced which exhibited higher saturation magnetization (252.85 Am2/kg) and lower value of coercivity (3.66 kAm-1), corresponded to the 12% content of Co in the film.
Effects of Non-Continuous TiO2 Buffer Layers on Structural and Electrical Properties of Indium Tin Oxide Thin Films
Authors: Yin Xue Song , Tang Wu , Weng Xiao Long , Deng Long Jiang
Published: September 2009

Indium Tin Oxide (ITO) films on polyethylene terephthalate (PET) sandwiching TiO2 buffer layers with different sputtering time have been prepared by rf-magnetron sputtering. Scanning Electron Microscope images of the TiO2 buffer layers showed the non-continuous growth in a typical sputtered film growing process. (400) oriented diffraction peaks appeared in all the ITO/TiO2/PET films. The electrical properties were measured by four point probe method and van der Pauw method. The variations of the resistivity and hall mobility on the sputtering time of TiO2 layer were studied. Furthermore, an exponential decay correlation of resistivity and the grain size was fitted. But the linear relationship between the ITO grain size and the mobility indicated by the grain boundary scattering theory didn’t appear here. The reason is believed to neglect the influence of the local variations of the lattice spacing and some other important scattering mechanisms such as lattice, ionized impurity, neutral impurity scattering, etc.
Fabrication of Self-Healing Ceramic Coating Against Oxidation for Carbon/Carbon Composite Using Polysilazane and Fillers
Authors: Liu Hong Li , Tian Chun Ying
Published: September 2009

The self-healing ceramic coating against oxidation for carbon/carbon composite was fabricated via preceramic polymer pyrolysis process using polysilazane as preceramic and MoSi2, B4C powders as fillers. By means of SEM and XRD, the phase compose and microstructure of coating were characterized, and preliminarily study on its anti-oxidation ability and thermal shock resistance were conducted. The results showed that, the coating is composed of the resisting oxidation layer and the sealing layer. The thickness of the coating is about 50μm, and the coating is uniform and densified. Good contact at the interfaces is visible on the SEM photograph. At 1300°C temperature, the thermal shock resistance test was conducted 50 times, the weight loss rate was 2.12%. In range of 1200°C~1500°C, the anti oxidation ability of the coating is good.
High Li+-Ion Storage Capacity and Multi-Electrochromism Behavior of Electrodeposited Molybdenum Doped Vanadium Oxide Films
Authors: Jin Ai Ping , Chen Wen , Zhu Quan Yao
Published: September 2009

Molybdenum doped vanadium oxide (Mo doped V2O5) xerogel films were prepared by cathodic electrodeposition on indium tin oxide (ITO) substrate from Mo doped V2O5 sol synthesized by sol-gel combined with hydrothermal reaction. Mo doped V2O5 xerogel films were deposited at different potentials between -0.01 V and -0.7 V vs saturated calomel electrode (SCE) with the potentiostatic mode. The structure was characterized for using X-ray diffraction (XRD), atomic force microscopy (AFM). These studies reveal that films consist of layered V2O5 host structure with various surface morphologies depending upon the deposition potentials. As shown by the cyclic voltammograms results, the films electrodeposited at -0.3 V exhibited Li+-ion storage capacity as high as ca. 70 mC/cm2 for the 50th cycle and showed multi-electrochromic behavior (orangered-green-blue) depending on the extent of intercalation during the electrochemical lithium insertion/extraction processes. It is proposed that the particles forming the films arrange directionally and crystallize partly, which lead to the enhanced electroactivity of vanadium oxide films by shortening the diffusion distance or quickening the transference rate of Li+ ions in the films.
Analysis of Water Transport Properties for Plant Structured Textile Fabric
Authors: Shi Xian Jun , Wu Ji Hong
Published: September 2009

Moisture/liquid transport in textile fabric is one of the critical factors affecting physiological comfort. Here we investigate the water transport properties of plant structures textile fabric, which was formed by mimicking the tree structure network. Our work shows that the water transport properties of the new type of material depend on its geometric structures, including the branching level and the diameter and length of the 0th branching level, and the structure fractal dimension. The more the length and the branching level, the lower the water transport capacity. A comparison of the plant structured textile fabric with the general fabric indicates that the plant structured fabric can provide higher moisture transport capacity and its maximum water transport capacity approach 1.707 times higher than that of the general fabric.
Induction Heating Deposition of Calcium Phosphate Coating on Carbon/Carbon Composites for Biomedical Applications
Authors: Xiong Xin Bo , Zeng Xie Rong , Zhou Chun Li
Published: September 2009

Calcium phosphate coatings were deposited on carbon/carbon composites by induction heating method at 353K. The phase, morphology and composition of the calcium phosphate coatings were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM) and the adhesion strength of these coatings and the scratched morphologies were determined by the scratch test and stereomicroscope (STM). The results show that when the solution concentration is less than 0.00125 M and pH value is large than 6, the phase of as-prepared coating is hydroxyapatite with Ca/P molar ratio of 1.67 or OCP with Ca/P molar ratio of 1.33, and when the solution concentration and pH value are in the range of 0.05-0.0125M and 5-6, the as-obtained coating are blends of brushite, monetite or OCP. These coatings have a porous morphology and are very easy to be scratched off. When the solution concentration is large than 0.05 M and pH value is less than 5, the as-prepared coatings are monetite with Ca/P molar ratio of 1. Among these monetite coatings, the coating on C/C prepared in 0.2M solution have highest bonding strength with a critical load of on average 13 N.
Photoaided Cathodic Protection of TiO2 Nanoparticle Coating on 304 Stainless Steel Substrate
Authors: He Ming Hui , Wang Ai Ping , Chen Shou Gang , Yin Yan Sheng
Published: September 2009

A uniform TiO2 nanoparticle coating was prepared both on steel and slide glass using sol–gel method and hydrothermal post-treatments. The particle size in the sol was determined to be ～2nm. The surface morphology and the structure of the coatings were analyzed by scanning electron microscope (SEM) and X-ray diffraction（XRD）, which revealed the surface was compact and well-distributed, and the main phase was anatase. UV-VIS spectrophotometer indicated that a absorption peak existed at 340nm. The anticorrosion performances of the coatings in dark and under ultraviolet illumination have been evaluated by electrochemical techniques.
Preparation and Characterization of CePO4 Coated ZrO2 Composite Powders by Hydrothemal Method
Authors: Wang Jing , Wang Xin , Zhang Wen Lai , Zheng Qiu Ju , Xu Ji Hui
Published: September 2009

The hexagonal and the monoclinic CePO4 with rod-like coated ZrO2 composite powders were successfully synthesized through the hydrothemal method. the coated powders were characterized by the techniques of XRD, TEM, DTA and zeta potential measurements. In addition, the morphology of the coated powders after calcinations at 1000°C was also investigated.
Preparation and Properties of Composite Antibacterial Agent Containing Copper and Zinc Ions
Authors: Ren Shu Xia , Yang Hui Fang , Tian Xiu Shu , Li Yan Fang
Published: September 2009

The composite antibacterial agents were prepared with Medical stone containing Cu2+ and Zn2+ by liquid ion-exchange reaction. The ion exchange capacity of the as-prepared Medical stone composite antibacterial agents (MSAA) products were investigated by ICP-AES, and the antibacterial activities of the agents were tested by Bacteriastasis ratio, and the structures were characterized by XRD and SEM. The results show that the conditions of preparation, such as pH, concentrations of copper and zinc ions, reaction time and reaction temperature, have important influences on the ion exchange of MSAA. The maximum ion exchange capacity have been obtained when 0.2mol/l Cu2+ and 0.6 mol /l Zn2+ reacted with Medical stone powers in the solution with pH values of 8 for 8 hours at 50 °C. Meanwhile good antibacterial activities and safety are also gained. The reasons for causing the above results are that copper and zinc ions can enter the framework of Medical stone through ion exchanging and adsorption, and are released slowly owing to its porosity.
Anti-Biofouling Property of a Novel Cross-Linkable Copolymer Grafted a Short Semifluorinated Aromatic Side Chain
Authors: Feng Shi Jun , Wang Qiang , Gao Yu , Huang Yan Gen
Published: September 2009

Biofouling on underwater engineered structures, especially on ship hulls, results in increased operational and maintenance costs. The traditional methods of protecting marine structures have been the use of toxic antifoulants, such as lead, mercury and tributyltin compounds (TBT). Such heavy metals have proven to be effective in deed, but severe shellfish deformities and the bioaccumulation of heavy metals in ducks, seals and fish lead to the global ban of toxic antifoulants. Therefore, our antifouling strategy is to develop minimally adhesive, mechanically stable and nontoxic fouling release coatings which degrade fouling an organism’s ability to adhere to surfaces. Herein we report on the synthesis and characterization of a novel cross-linkable copolymer grafted a semifluorinated aromatic side chain which was prepared by copolymerization with methyl methacrylate and glycidyl methacrylate. Bulk and surface properties were assessed through 1H NMR and 19F NMR spectra, contact angle measurement. The cross-linkable copolymer was rationally designed for use as coating to prevent marine bioufouling. Apart from the use of methyl methacrylate and glycidyl methacrylate which contained epoxide ring serving as a cross-linked group, the other important monomer―a semifluorinated group substituted styrene monomer was selected to construct a low surface energy material. Finally, the antifouling potential of the designed polymer surface was evaluated employing the fouling diatom Nitzschia in our laboratory. Experimental results indicated the combination of the low surface energy group (semifluorinated segments) and linker group (epoxide ring) allowed the cross-linkable polymer surface possessing a little better antifouling properties than that a standard poly(dimethyl siloxane) (PDMS) coating.
Pitting Susceptibility and Semiconducting Properties of Passive Films of 18Cr-18Mn-2Mo-0.9N High Nitrogen Austenitic Stainless Steel
Authors: Li Hua Bing , Jiang Zhou Hua , Li Zhen , Zhang Zu Rui
Published: September 2009

The effects of pH value and chloride ions concentration of the solution on pitting susceptibility and semiconducting properties of passive films formed on 18Cr-18Mn-2Mo-0.9N high nitrogen austenitic stainless steel (HNSS) were investigated using potentiodynamic polarization and capacitance measurement methods, respectively. The anodic polarization curves show that HNSS exhibits excellent pitting corrosion resistance in the solution with different pH values and chloride ions concentration, and the pitting corrosion resistance of HNSS decreases a little with decreasing the pH value or increasing the chloride ions concentration of the solution. The passive films formed on HNSS in the solution with pH values ranging from 1 to 9 or chloride ions concentration from 3.5 wt% to 20 wt% NaCl behave as n-type semiconductors. With increasing the pH value or decreasing the chloride ions concentration, the shallow donor and deeper donor densities decrease and the flat bland potential decreases, and the thickness of space charge layer increases. The deeper donor increases and then the second positive slope of straight linear region disappears with decreasing the pH value or increasing the chloride ions concentration of the solution, which can be attributed to the formation of Cr6+ is depressed.
Void Formation in the Growing Scale Induced by the Divergence of the Diffusive Ionic Flux in High Temperature Oxidation of Metals
Authors: Maruyama Toshio , Ueda Mitsutoshi , Kawamura Kenichi
Published: September 2009

Voids are frequently generated and dispersed in oxide scales formed in high temperature oxidation of metals. The divergence of ionic flux may play an important role in the void formation in a growing scale. Kinetic equations were derived for describing chemical potential distribution, ionic fluxes and their divergence in the scale. The divergence was found to be the measure of void formation. Defect chemistry in scales is directly related to the sign of divergence and gives an indication of the void formation behavior. The quantitative estimation on the void formation was successfully applied to a growing magnetite scale in high temperature oxidation of iron at 823 K.
Interrelation between Hydrogen Desorption Kinetics and Structure of (Mg2Ni)Hx and Hydrogenated Eutectic(Mg/Mg2Ni)Hy
Authors: Cermak Jiri , Král Lubomir
Published: September 2009

Mg-rich alloys of the binary system Mg-Ni are prospective hydrogen-storage materials. In the present study, desorption characteristics of hydrided Mg2Ni intermetalic and hydrided Mg/Mg2Ni eutectic mixture were investigated. Structure of experimental materials during the hydrogenation was observed by SEM. Three modifications of (Mg2Ni)Hx (x ~ 4) were prepared differing in the ratio of two low-temperature phases f = LT2/LT1: with (i) f >1, (ii) f ~ 1 and with (iii) f <1. Evolution of the ratio f during hydrogen desorption was checked by XRD. It was found that the micro-twinned phase LT2 is not desirable in hydrogen-storage materials containing Mg2Ni intermetallic. Diffusion coefficient of hydrogen in LT2 is about 20 times lower than in LT1.
Effect of the Si Additions on the Mechanical Behaviour and High-Temperature Performance of Hydrogen Sintered 434L Stainless Steels
Authors: Bautista Asuncion , Velasco Francisco , González-Centeno A.
Published: September 2009

Non-commercial, 434L ferritic stainless steel powders prealloyed with 2% of Si were uniaxially compacted at 700 MPa and sintered in 100% H2 atmosphere for 30 min at three different temperatures (1225, 1250 and 1275 °C). For comparison, standard, commercial 434L powders were sintered in the same conditions, and 434L+2%Si powders were also sintered in vacuum. The porosity and grain size of the 9 sintered stainless steels were measured by image analysis methods. Tensile strength and Vickers hardness tests show that the steels with 2% of Si exhibit higher mechanical properties. Oxidation tests were carried out in air at 800 and 900 °C. H2-sintered 434L steels prealloyed with Si exhibit higher weight gains per unit of apparent surface than 434L steels sintered in the same conditions, due to the higher porosity of the former. The sintering atmosphere affects the nature and morphology of the scales observed by XRD and SEM. Vacuum sintering of 434L+2%Si stainless steels promotes the formation of more protective scales and lower mass gains (for identical porosity volume) than H2 sintering.
Numerical Determination of Intrinsic Diffusion Coefficient of Aluminide Coatings on Metals
Authors: Wierzba Bartłomiej , Chevalier Sébastien , Politano Olivier , Danielewski Marek
Published: September 2009

This paper presents a numerical method to determine the composition dependent diffusivities and to predict the concentration profile during the interdiffusion process. The intrinsic diffusion coefficients in diffusion aluminide coatings (Fe-Al) were determined at 1000oC. The obtained diffusion coefficient for iron in Fe3Al or FeAl is in the range 10-10 to 10-9 cm2.s-1. The aluminum diffusion coefficient varies from 10-11 to 10-7 cm2.s-1 in the same phases.The present approach also permits to model the reactive diffusion in the Fe-Al systems.
Selected Observations in Phase Constituents, Growth Kinetics and Microstructural Development of Aluminides in U-Mo vs. Al and 6061 Diffusion Couples Annealed at 600°C
Authors: Perez E. , Keiser Dennis D. , Sohn Yong Ho
Published: September 2009

This paper presents selected experimental observations of phase constituents, growth kinetics, and microstructural development of aluminide phases that develop in solid-to-solid diffusion couples assembled with U-7wt.%Mo, U-10wt.%Mo and U-12wt.%Mo vs. Al and 6061 alloy after a diffusion anneal at 600°C for 24 hours. Scanning electron microscopy coupled with energy dispersive spectroscopy, electron microprobe analysis, and transmission electron microscopy via focused ion beam in-situ lift-out were employed to characterize the interaction layer that develops by interdiffusion. While concentration profiles exhibited no significant gradients, microstructural analysis revealed the presence of extremely complex and nano-scale phase constituents with presence of orthorhombic--U, cubic-UAl3, orthorhombic-UAl4, hexagonal-U6Mo4Al43 and diamond cubic-UMo2Al20 phases. Presence of multi-phase layers with microstructure, which suggest a significant role of grain boundary diffusion, was observed.