Applied Mechanics and Materials Vol. 320

Abstract: NiZn ferrite material TN40S-X was fabricated by conventional oxide ceramic method. The test results show that the material possesses high mechanical strength and high saturation flux density (B_s),and it is suitable for low profile power inductors with dual requirements of mechanical strength and saturation flux density.

Abstract: The process of preparation of Fe-Si cores is studied, and the influence of different amounts of insulating compounds addition on magnetic properties of the cores is discussed. The results show that the effective permeability is 71.4 when the amount of insulation is 0.5 wt%. When the content is increased to 2.5 wt%, the DC Bias characteristic becomes the best. When the insulating compounds addition is 2.5 wt%, the sample has the lowest power loss, which is 308.4 mW/cm³ at f=50 kHz and B=50 mT.

Abstract: M-ZrO₂ nanoparticles with a diameter range of about 10 nm are successfully synthesized with zirconium nitrate as zirconium source and stronger ammonia water as precipitant at 210 °C for 48 h via the easy hydrothermal method. The phase, the morphologies and optical absorption properties of the samples have been characterized and analyzed by X-ray diffraction (XRD), field-emission transmission electron microscopy (TEM) and ultraviolet-visible absorption spectroscopy (UV-VIS), respectively. XRD analysis shows that the phase of as obtained samples is M-ZrO₂. TEM analysis confirms that the increase of the reaction temperature is in favor of the synthesis of M-ZrO₂ nanoparticles. And UV-VIS measurements show that M-ZrO₂ nanoparticles have a good optical absorption property.

Abstract: CuO microrods with a diameter range of 1-2 μm are successfully synthesized with 1 m mol CuCl₂ as copper source and 1 m mol Na₂CO₃ as auxiliary salt at 240 °C for 24 h via the simple hydrothermal method. The phase, the morphologies and optical absorption properties of the samples have been characterized and analyzed by XRD (X-ray diffraction), SEM (Scanning electron microscope) and ultraviolet-visible absorption spectroscopy (UV-VIS), respectively. XRD analysis shows that the phase of as obtained samples is CuO. SEM analysis confirms that the increase of the reaction temperature is propitious to synthesize CuO microrods. And UV-VIS measurements show that CuO microrods have a good optical absorption property.

Abstract: Adopting carbonyl iron powder and silicone/mineral oil as suspend phase and dispersed phase separately,and silica, kaolin as lubricant additives,magnetorheological (MR) fluid was prepared by ball milling. The apparent viscosity of base oil and shear stress were measured on a modified rotational viscometer. The experimental results demonstrated that an appropriate viscosity of base oil contributed to the rheology of MRF. Adding a small amount of thixotropy into MRF had little influence on zero-field viscosity, which facilitated the application of MRF to maintain adequate liquidity. Under low shear rate conditions, the shear stress was improved by adding thixotropy to some extent, especially in the mineral oil-based magnetorheological fluid, in which the role of silica was superior to kaolin.

Abstract: SiC nanowires have been synthesized by microwave-vacuum heating method at 1480°C, using silicon powders, silica dioxide powders and artificial graphite as raw materials. SEM, TEM and XRD were employed to investigate the micro-structure of obtained specimens. It was shown that β-SiC can be directly synthesized directly without any catalyst on the basis of the vapor-solid (VS) growth mechanism. The obtained specimens exhibited various morphologies and sizes, due to the differences in the reaction temperatures and the distribution of components in the crucible. Products existed in upper crucible were bright-green and more pure, mainly consisting of nanorods with a diameter of about 150nm and some SiC micro-crystals. At the same time, the surface oxidation phenomenon was not obvious. As to the grey-green products existed in other zone, lots of SiC/SiO₂ coaxial nanowires with a diameter around 20-50 nm (the thickness of SiO₂ surface layer was about 2nm) were successfully obtained. Besides, there also remained some un-reacted graphite and silica dioxide. The excitation light with wavelength of 240nm was used to test the photoluminescence properties of the products. Results showed that both of the SiC nanorods and SiC/SiO₂ coaxial nanowires exhibited a strong broad photoluminescence peak at wavelength of about 390nm, displaying a higher degree of blue-shift in comparison to the reported luminescence results of β-SiC nanomaterials.

Abstract: TiO₂ nanotube arrays were made on the titanium foil by the method of anodic oxidation. Large-area crystallized free-standing TiO₂ nanotube arrays were fabricated by a two-step anodization, and then crystallized by different heat-treatment processes. The morphology and structure of the TiO₂ nanotube arrays were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that the diameter of the TiO₂ nanotube at the voltage range of 50V~65V was about 100nm. Anatase phase is the unique phase observed in free-standing TiO₂ arrays annealed at the temperature of 400°C~610°C. However, crystallographic orientation of anatase phase is influenced by the annealing temperature.

Abstract: The Al₂O₃-doped ZnO(AZO) films were deposited on the glasses by means of RF magnetron sputtering technology. The films were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and Profile-system respectively. The effect of substrate temperature on the structure of the AZO films is investigated.As a result, the properties of the AZO thin films are remarkably influenced by the substrate temperature , especially in the range of 200°C to 500 °C. The film prepared at the substrate temperature of 400°C possesses the best crystalline.

Abstract: Ho-doped Yttrium aluminum indium garnet, Y₃Al_4.5In_0.5O₁₂ (YAIG), was synthesized by co-precipitation method. Effects of Ho concentration, reaction mechanism, crystallinity and luminescence properties of the phosphor powders were studied using the X-ray diffraction, thermo-gravimetry Analyzer,scanning electron microscopy and photoluminescence. The performances of samples were analyzed by changing the concentration of Ho³⁺ and the substitution of indium for aluminum. The results showed that pure cubic garnet phase was formed in the Indium-substituted samples, and the critical distance of the energy transfer was 1.41 nm. Both the excitation and emission intensities increased firstly and then decreased with the increasing of Ho³⁺ concentration. When the concentration of Ho³⁺ reached 15%, the photoluminescence property of the sample was best.