Advanced Materials Research Vols. 399-401

Abstract: A micromechanical model for single-fiber pull-out test of fiber-reinforced viscoelastic matrix composites is established. It includes fiber, interphase and viscoelastic matrix. The formulas to calculate the fiber axial stress, the interphase shear stress, and the matrix axial and shear stress are obtained. Moreover, for Kevlar aramid fiber reinforced viscoelastic matrix composites, the influences of the interphase thickness, the fiber embedded length and volume fraction on the stress distributions of fiber and interphase is studied. Some analysis results show that, with the increase of normalized fiber axial distance, the fiber axial stress increases monotonically, but the interphase shear stress decreases. The stress distributions of fiber and interphase change with the variation of the interphase thickness, the fiber embedded length and volume fraction.

Abstract: A new synthesis technology of titanium carbide with microwave is introduced in this article. Microwave synthesis technology is a fast and relatively low temperature of synthesis method. Nano-titanium carbide powders were synthesized by carbothermal reduction of titanium dioxide and carbon black with the microwave synthesis method at 1100°C-1400°C in argon gas atmosphere. Nano-TiO₂ powder and carbon black were used as raw materials. The TiC powders were characterized with the XRD and TEM. The experimental results show that the synthesis rate is quick, even at relatively low synthesis temperature. The average particle size of the TiC powders synthesized by the microwave synthesis technology under low temperature (<1300°C) is less than 50nm, and the average particle size augments with increasing the microwave synthesis temperature and time.

Abstract: Abstract. Zn nanoparticles prepared by the arc was used in the present study. The microsturcture, oxygen content and oxygen atom position in Zn nanoparticles were investigated. Furthermore, the variation of oxygen content with time in the Zn nanoparticles was also studied. The results showed that the effective size of oxidized Zn nanoparticles was about 100nm, and oxidation process was conducted on the surface. On the other hand, the oxygen content in oxidized Zn nanoparticles reduced by comparing with that laying in the air for the same time.

Abstract: High quality NaYF₄ and NaYF₄:Er³⁺ materials were prepared using EDTA-assisted hydrothermal method. The effects of doping of Er³⁺ on the shape of samples were discussed. The samples were characterized by X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). XRD patterns show that the samples are hexagonal phase of NaYF₄ and NaYF₄:Er³⁺ with good crystallization. SEM images present that the samples of NaYF₄ are homogeneous nanorods with a diameter of 342 nm and a length of 1043nm，the NaYF4:Er3+(5%) sample with a diameter of180.7nm and a length of 1220nm, and NaYF₄:Er³⁺(10%) with a diameter of 139.4nm and a length of 939.9nm.The sizes of the NaYF₄ and NaYF₄:Er³⁺ nanoparticles are basically consistent with that calculated from XRD peak via the Scherrer equation.

Abstract: The micro-structure, the thermal and electrical transport properties, and their corresponding relationship of carbon micro-coils were discussed, based on the experimental results. The disordered micro-structure and the helical conformation of carbon micro-coils were responsible for the characteristic of their transport properties.

Abstract: Nanometer ferric oxide (α-Fe₂O₃) powders were prepared by improved hydrolysis method from industrial byproduct ferrous sulfate septihydrate (FeSO₄•7H₂O) and industrial grade ammonium bicarbonate (NH4HCO3). The structural properties were characterized by X-ray diffraction (XRD), scanning electron microscopy(SEM), transmission electron microscopy (TEM), difference of thermodynamic analysis (DTA). The results revealed that the phase of ferric oxide powders mainly consisted of spherical α-Fe₂O₃. The α-Fe₂O₃ particles were relatively uniform in size and the average size of particles is 40nm. The effects of many technical factors on growing and properties of nanometer ferric oxide particles, such as the reaction time and temperature, pH value of system, calcined temperature etc were discussed in this paper.

Abstract: In this paper, porous flower-like nickel oxide (NiO) on glass substrates were prepared by an aqueous chemical growth based technique. The morphology and optical observed were found to be influence by the reaction time. Field Emission Scanning Electron Microscopy (FESEM) revealed a porous flower-like structure growth on the substrates investigated. The optical band gap for NiO thin film calculated from transmission spectra has increased from 3.72 eV to 3.91 eV with the increasing of reaction time. This result shows that the growth time have some influence on morphology and optical of NiO films.

Abstract: A novel soft template method is reported to control gold nano or microstructrues. Gold nanowires with two-dimensional (2-D) network structure were prepared by anionic polymer (sodium carboxymethyl cellulose, CMC) reduction of HAuCl4. Big gold microkites were synthesized using CMC-cationic surfactant (dodecyl trimethyl ammonium chloride, DTAC) templates. Quasi-spheric_{Subscript text}al gold nanopartilces were obtained through CMC-anionic surfactant (sodium dodecyl sulfate, SDS) templates. Electron diffraction suggested that the 2-D networked nanowires and microkite heads were single crystalline. Ultraviolet visible (UV-vis) absorption spectrum of gold structure obtained showed that there were anisotropic structure formed in reacted solutions. It is potential method to gain preferred noble metal structures by this soft template.

Abstract: Vanadium oxide film is a common sensing film for infrared detector and uncooled infrared imaging devices, its stability directly affects the use of the thetse infrared devices.In this paper, high and low temperature cycles fatigue tests was used to check and compare the stability of the vanadium oxide films formed by different methods.The change of the temperature coefficient of resistance(TCR) and the room temperature resistance were measured and compared for the vanadium oxide film prepared by reactive sputtering and vanadium dioxide films by Ion Beam Enhanced Deposition(IBED) method. The result indicated tungsten doped Vanadium dioxide film by IBED is the most stable and has a higher TCR.

Abstract: A method to prepare nickel oxide material which has a high purity and nano-sized particle was developed. nano NiO was synthesized by sol-gel method using nickel alkoxide as precursors. The structural characterization of the obtained materials was performed by thermal analysis TG-DTA, X-ray diffraction (XRD), Laser Raman spectra and Transmission Electron Microscopy (TEM). The characterization results indicated that NiO nano-particles (size 25–35 nm) are obtained by hydrolyzing of metal alkoxide of Ni(OCH₂CH₂OH)₂ and possess high purity.