Applied Mechanics and Materials Vols. 275-277

Abstract: Bromine carbon alkyd resin was synthesized with soya oil acid, pentaerythritol, phthalic anhydride and brominated epoxy resin as materials under the condition which reaction temperature for 200 °C, usage of catalyst was 0.1% and period of esterification reaction lasted 3 h. And then bromine carbon alkyd resin retardant coatings for steel structure was prepared using bromine carbon alkyd resin as binder which compounded with flame retardant additives through stirred, grinded and dispersed homogeneously. Resin and coatings were analyzed by infrared spectroscopy and TG-DSC. The optimal formula of bromine carbon alkyd resin retardant coatings for steel structure was achieved through testing impact resistance, adhesive force, hardness, gloss, drying time and fire resistance time of film.

Abstract: Keywords: Electroless plating Ni, CeO2, Micro-connection pad, Wire bonding Abstract. It is Ni/CeO2 coatings that have been prepared on SiC/Al composites surfaces (electroless plating Ni and depositing CeO2 conversion coatings). It is employed to wire bonding process as a new micro-connection pad in this paper. During bonding process, ultrasonic time, ultrasonic power, bonding pressure, etc. have been investigated. The optimized parameters are obtained with the best bonding properties.

Abstract: In order to obtain a nanocrystalline and amorphous structure in the Mg2Ni-type alloy, the melt spinning technology has been used to prepare the Mg20Ni8M2 (M = Co, Cu) hydrogen storage alloys. The microstructures of the alloys were characterized by XRD, SEM and HRTEM. The effects of the melt spinning on the gaseous and electrochemical hydrogen storage kinetics of the alloys were investigated. The results indicate that the as-spun (M = Co) alloys display a nanocrystalline and amorphous structure as spinning rate grows to 20 m/s, while the as-spun (M = Cu) alloys hold an entire nanocrystalline structure even if a limited spinning rate is applied, suggesting that the substitution of Co for Ni facilitates the glass formation in the Mg2Ni-type alloy. The melt spinning remarkably ameliorates the gaseous hydriding and dehydriding kinetics of the alloys. As the spinning rate is raised from 0 (As-cast was defined as the spinning rate of 0 m/s) to 30 m/s, the hydrogen absorption saturation ratio ( ), a ratio of the hydrogen absorption capacity in 5 min to the saturated hydrogen absorption capacity, are enhanced from 80.43% to 94.38% for the (M = Co) alloy and from 56.72% to 92.74% for the (M = Cu) alloy. The hydrogen desorption ratio ( ), a ratio of the hydrogen desorption capacity in 20 min to the saturated hydrogen absorption capacity of the alloy, are increased from 24.52% to 51.67% for the (M = Co) alloy and from14.89% to 40.37% for the (M = Cu) alloy. Furthermore, the high rate discharge ability (HRD) and the hydrogen diffusion coefficient (D) of the alloys notably mount up with the growing of the spinning rate.

Abstract: Two kinds of microcapsules were synthesized with paraffin and the mixture of n-butyl stearate and n-tetradecyl alcohol as the core material, and the melamine-formaldehyde (MF) resin as shell material, respectively. In this way, the infrared stealthy coatings were prepared by using the as-synthesized microcapsules, the hollow glass microspheres and other auxiliaries. The surface morphology of the microcapsules were investigated by using scanning electron microscopy (SEM). By using the contactless infrared thermometer measurement and radiation rate test device, the radiation exitances of coatings were determined. The radiation exitance of infrared stealthy coatings is lower than the common coatings, which improved the performance of infrared stealthy of destination.

Abstract: ZnO is a novel kind of semiconductor material, which has hexagonal Wurtzite crystal structure, with a wide band-gap of 3.37eV at room temperature. It owns a large excitation binding energy of 60meV and excellent room temperature stability. ZnO has very useful properties of piezoelectricity, gas & pressure sensitivity etc. Therefore, application researches on low dimensional ZnO materials have become hot topics and significant values.In this paper, ZnO doped thin films were prepared by sol-gel method. Zn (CH3COO)2•2H2O was employed as the precursor, anhydrous alcohol was the solvent, monoethanolamine was the complexant, Co(CH3COO)2•4H2O was used as the source of the Co-dopant, Al(NO3)3•9H2O was used as the source of the Al-dopant in the experiment to yield the doped ZnO films. The sample preparation spin coating number is 6, the average grain size is in nanometer level, and the thermal treatment temperature is 450, 500, 550, 600°C, respectively. The effect of the doping proportion on the crystallization and energy band structure of the ZnO thin films were characterized by X-ray diffraction (XRD), the Infrared spectrum and the ultraviolet-visible transmission spectra (UV-Vis).The results show that the crystalline grain size of the ZnO doped films grown on glass substrates increases, since the thermal treatment temperature rise. In this paper, a best ZnO doped film was obtained at the temperature of 600°C. It preliminarily analyses that Co-doped ZnO films present a absorption peak in infrared area when the thermal treatment is at 550°C. Al or Co doped ZnO films can cause a redshift of ultraviolet absorption peaks. Energy gap is around 3.2eV when doped. The ultraviolet absorption peaks of Al-doped ZnO films will have a shift to high energy, since it has a better crystallinity.

Abstract: Using the radio frequency reactive magnetron sputtering technique, ZnO:N thin films were fabricated on glass substrate by changing the Ar/N2 flow ratio from 9/1 to 9/4. The samples were characterizated on the film microstructure and optical properties by XRD, UV- visible spectrophotometer and Fourier transform infrared spectroscopy. The XRD results show that no significant peaks appeared at less N flow and the light transmission rate of UV-Vis has Small fluctuations between 320~780nm wavelength ; with increasing N flow, there was only (002) single peak in curves of XRD, transmittance of UV had a sharp decline below the 400nm wavelength; when argon-nitrogen flow ratio was increased to 9/4, it is show that there were two peaks near 34°of 2θ in curves of XRD but no significant change in UV transmittance.

Abstract: New functional nanocomposite FePt:C thin films with FePt underlayers were synthesized by noneptaxial growth. The effect of the FePt layer on the ordering, orientation and magnetic properties of the composite layer has been investigated by adjusting FePt underlayer thickness from 2 nm to 14 nm. Transmission electron microscopy (TEM), together with x-ray diffraction (XRD), has been used to check the growth of the double-layered films and to study the microstructure, including the grain size, shape, orientation and distribution. XRD scans reveal that the orientation of the films was dependent on FePt underlayer thickness. In this paper, the TEM studies of both single-layered nonepitaxially grown FePt and FePt:C composite L10 phase and double-layered deposition FePt:C/FePt are presented.

Abstract: The highly luminescent cadmium telluride quantum dots (CdTe QDs) have been synthesized by using N-acetyl-L-cysteine (NAC) as stabilizer in aqueous solution. Experiments indicate that the QDs nanocrystals could grow larger as the extension of reaction time, causing the red shift of emission spectra. The typical product was analyzed by fluorescence spectroscopy, high-resolution transmission electron microscope (HRTEM), x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The morphological and structural characterization confirmed the formation of monodisperse CdTe QDs with several nanometers in size.

Abstract: The present work reports the electrochemical anodization for porous silicon microcavity (PSM) fabrication, including the number of layers and electrochemical process effect in the optical response quality of PSM. These PSMs have been obtained by using PS technology. It is found that the electrochemical process limits the maximum number of layers because there is a chemical dissolution effect during electrochemical anodization. The reflectance spectra of the PSMs indicates that stop-band and the resonant peak of the PSM shift down with the increases of the number of layers due to the decrease of layer's thickness. The value of the full width at half maximum (FWHM) dependents on the number of layers, and the number of layer increases when the FWHM decreases, which is due to the light scattering at roughness interface layer.

Abstract: TiO2-doped ZnO thin films with highly (002)-preferred orientation were grown on glass substrates by RF magnetron sputtering. The effect of substrate temperature on structure and optical properties of the films were investigated by X-ray diffractometer and spectrophotometer. The results show that the polycrystalline TiO2-doped ZnO films consist of the hexagonal crystal structures with c-axis as the preferred growth orientation normal to the substrate. The substrate temperature significantly affects the crystallite size and optical transmittance of the deposited films, but slightly influences the refractive index and optical bandgap of the deposited films. The TiO2-doped ZnO film grown at substrate temperature of 470 K possesses the maximum crystallite size, an average transmittance of 76.2 % in the visible light range, and an optical bandgap of 3.46 eV.