Advanced Engineering Materials

Volumes 194-196

doi: 10.4028/

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Authors: Jun Hui Meng, Dong Xu Liu, Yi Zhang, Zhao Jia, Ming Yun Lv
Abstract: Tear propagation is a typical breakage modality of fabric laminates. In this paper, analysis methods and their empirical formulas about tear propagation of a kind of fabric laminate which is used in high altitude lighter-than-air vehicle (LTA) is studied. The methods include Griffith’s energy balance method, Thiele’s empirical formula method, Stress field consideration method and critical stress intensity factor method. Testing about tear propagation strength in biaxial stress is done by a tailor-made testing machine to study on the methods. And then a comparison is drawn between these formulas and results of the experimentation. Subsequently, advantages and disadvantages of these formulas and their scope of application are concluded. While by using the empirical formulas, the analysis of tear propagation of different incision shapes is given. It is useful for the further study on different fabric laminates.
Authors: Jun Zhang, Le Xi Shao, Wei Xie, Chang Wei Zou
Abstract: Nitrogen and Aluminum co-doped ZnO thin films were prepared by In Situ thermal oxidation of RF magnetron sputtered Zn3N2:Al films on quartz glasses. The structural, optical and electrical properties of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical transmittance, photoluminescence (PL) and Hall effect measurements. XRD analyses revealed that Zn3N2:Al films entirely transformed into ZnO films after annealing in oxygen at 500 °C for one hour. Hall effect measurements confirmed p-type conduction in ZnO films with a low resistivity of 34.8Ω cm, a high hole concentration of 3.26×1017 cm-3 and a Hall mobility of 2.3 cm2/Vs. Optical transmission spectra shows that the films are highly transparent in the visible region . Our results demonstrate a promising approach to fabricate low resistivity p-type ZnO.
Authors: Jing Rong Chi, Ping Fan, Guang Xing Liang, Dong Ping Zhang, Xing Min Cai, Zhuang Hao Zheng, Tian Bao Chen
Abstract: To evaluate the influence of plasma power on the structural, electrical and optical properties of Al-doped ZnO (AZO) films, a set of polycrystalline AZO samples under different plasma power were deposited on glass substrates at room temperature. X-ray diffraction technique (XRD), four-point probe measurements and spectrophotometer were used to characterize these films. XRD shows that all AZO films have a hexagonal wurtzite structure with prominent (002) orientation. With the plasma power increasing, the grain size first increases and then decreases. The largest grain size of 23.6 nm in the films is obtained at the plasma power of 123 W. The average optical transmittance of AZO films is over 80% in the visible region. The lowest resistivity of 1.0×10-3Ω•cm is obtained under the plasma power of 220 W.
Authors: Chun Feng Song, Ke Chen, Zhong Hua Ni
Abstract: The use of photoconductive film improves the flexibility of dielectrophoretic device and the optoelectronic tweezers provides dynamically reconfigurable optical electrode which provides effective technology in the bio-particles parallel manipulation. In this paper, a circle floating electrode and a castellated shape optical electrode are designed in the lateral-field optoelectronic tweezers. The gradient of the square of the electric field is analyzed as the main parameter. The simulation results show that the floating electrode changes the distribution of the electric field and improves the manipulation capability in the region between the strip electrodes. The castellated shape electrode extends the strip electrode and performs the capability of the traditional physical castellated shape electrode. On the same condition the peak value of x direction of the gradient of the square of the electric field is about 15% smaller than the traditional physical electrode mode because the potential decays in the photoconductive film. To obtain the reconfigurable capability, this shortcoming can be overcome by increasing the applied AC signal voltage.
Authors: Wen Gang Yao, Qian Cheng
Abstract: Different physical properties of laser-damaged HfO2 film on SiO2 substrate were detected by scanning probe acoustic microscope. Surface topographies of SPM showed that the depth of laser-damaged hole on the HfO2 film was close to the thickness of film, while the phase images in probe-vibration mode of SPAM showed that the hydrophilicity of damaged area of HfO2 film was higher than undamaged area which led to stronger absorption to water vapor in air. Some scratches on SiO2 substrate surface under HfO2 film was found in the acoustic images in sample-vibration mode of SPAM.
Authors: Feng Zhu, Gui You Wang, Qiang Xu
Abstract: Stable one component heat cured polyurethane-acrylate (PUA) sealants were synthesized using dicumyl peroxide (DCP) as an initiator with high decomposition temperature. The PUA sealants were synthesized through the reaction of hexamethylene diisocyanate (HDI) with poly(ethylene buthlene glycol adipate) and 2-hydroxyethyl methacrylate (HEMA), and the PUA sealants were stably stored under accelerated aging test at 60°C . The structure of polyurethane prepolymer, PUA prepolymer, PUA sealant and its cured film were characterized by FT-IR, 1H-NMR and Raman spectra.
Authors: Lian Ping Chen, Yuan Hong Gao, Jian Xiong Yuan, Qing Hua Zhang, Yan Hong Yin, Chun Xiang Wang
Abstract: It is hardly possible to obtain rare earth doped CaWO4 thin films directly through electrochemical techniques. A novel post processing has been proposed to synthesize CaWO4:Eu3+ thin films at room temperature. X-ray diffraction, X-ray photoelectron spectrometry, spectrophotometer were used to characterize their phase, composition and luminescent properties. Results reveal that Eu3+-doped CaWO4 films have a tetragonal phase; the content of Eu in the near surface region is much higher than that of the bulk; under the excitation of 310 nm, a sharp emission peak at 616 nm has been observed for Ca0.9WO4:Eu0.13+ thin films.
Authors: Jumril Yunas, Azrul Azlan Hamzah, Majlis Burhanuddin Yeop
Abstract: In this paper, a theoretical analysis of thin film oxide resulted from lumped element model analysis using ASITIC simulation tool is presented. The study is aimed to investigate the effect of the oxide thickness on the electrical characteristics of planar micro-coils. Some important device parameters, such as parasitic capacitances and resistances caused by oxide and substrate layer, and quality factor of the planar coil, as well as the characteristic of the magnetic field coupled between the coils are analyzed in wide range of operating frequency. The simulation results show that there is significant influence of the oxide thickness to the device characteristics. It is shown that by increasing the thickness of the oxide layer on the substrate, a high Q-factor of 5 can be obtained, while the magnetic coupling is improved when the thickness of the oxide layer residing between metal layers is reduced.
Authors: Jun Liu, Jing Wang, Ya Ting Zhang, Wen Ping Geng, Xiu Jian Chou
Abstract: By the sol-gel process, Pb0.97La0.02(Zr0.95Ti0.05)O3 (PLZT) antiferroelectric (AFE) thin films with different thicknesses were successfully deposited on Pt(111)/Ti/SiO2/Si(100) substrates. The phase structure of the PLZT antiferroelectric thin films was studied by X-ray diffraction (XRD) analyses. The electric field-induced AFE-FE phase transformation behavior of the PLZT thin films,was examined by polarization versus field (P-E) and relative permittivity versus field (C-E) measurements, with priority focused on thickness-dependent phase switching field. The current by the polarization and depolarization of polar in the PLZT films was measured through current density-electric field (J-E) measurement. With the increase of film thickness, the maximum polarization less and less, the maximum current density is increasing.
Authors: Bao Lin Xing, Chuan Xiang Zhang, Lun Jian Chen, Guang Xu Huang
Abstract: Activated carbons (ACs) were prepared from lignite by microwave (MW) and electrical furnace (EF) heating with KOH as activation agent. In order to compare pore structures and electrochemical performances of ACs prepared by both heating methods, the ACs were characterized by N2 adsorption at 77K, X-ray diffraction (XRD) and scanning electron microscope (SEM). The electrochemical performances of Electrochemical capacitors (ECs) with ACs as electrodes in 3mol/L KOH electrolyte were evaluated by constant current charge-discharge, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the pore structures of ACs prepared by MW and EF heating significantly enhance when the weight ratio of KOH to coal increases from 2 to 4. The BET specific surface area, total pore volume, the ratio of mesopore and average pore diameter of ACs prepared by MW heating (denoted as AC-MW4) reaches 2094m2/g, 1.193cm3/g, 53.6%, 2.28nm when the weight ratio of KOH to coal is 4, and ACs prepared by EF heating (denoted as AC-EF4) reaches 2580m2/g, 1.683cm3/g, 67.3%, 2.61nm. The ECs with AC-MW4 and AC-EF4 as electrodes present a high specific capacitance of 348F/g and 377F/g at a current density of 50mA/g, and still remain 325F/g and 350F/g after 500 cycles, respectively. Although the specific surface area, total pore volume and specific capacitance of ACs prepared by MW heating are slightly lower than EF heating, taking into account the heating time in the activation process, ACs prepared by EF heating needs approximate 140min, while MW heating only needs 10min, which have demonstrated that microwave heating technology is a promising and efficient technique to prepare ACs.

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