Applied Mechanics and Materials Vols. 313-314

Abstract: We studied optical properties of copper nanowires fabricated by a shadow deposition method. We found that the optical absorption spectra of thinner nanowires exhibited stronger anisotropic absorption than thickner nanowires. Absorption maxima are located at lower photon energy when incident field is parallel to the wire axes than they are perpendicular to each other. They also shift to lower energy when the widths of nanowires are increased.

Abstract: The calculation of the stress distribution in the forming stage of sheet metal forming is critical to the accuracy of springback simulation. In order to improve the accuracy of stress prediction, a new mixed shell element is presented. Two pseudo nodes are added in the thickness direction so that the normal strain can be calculated using the displacements of the nodes. Mixed formulation is used instead of that of pure displacement. As a result, the accuracy of stress prediction is improved. Examples are given to show the improvement.

Abstract: In the paper, we research the flow state and the pressure of the oil film between the parallel and the deformed friction pairs to reveal the oil film state between the friction pair in hydro-viscous drive. Firstly, 3D physical models of the oil film were established. Then, the models were solved based on the principle of computational fluid dynamics. We found that the dynamic pressure goes up gradually along the radial direction; at zone with groove the dynamic pressure is higher, and the dynamic pressure between deformed interfaces is lower than that between parallel interfaces. The velocity of the oil film increases along the radial direction, and that between deformed interfaces is higher. The numerical results can provide some theoretic basis for the study of the HVD technology.

Abstract: t is important for dynamic characteristics of electromagnetic release with oil dashpot to calculate the oil damping force. The formula of the oil damping force is deduced by the theoretical formula of viscous damper or according to the experimental results. Therefore, a way to analyze oil damping force of electromagnetic release with oil dashpot is proposed based on Fluent due to the limitations of the two methods in this paper. The curve which is the speed of the plunger variations of the oil damping force is drawn through the numerical analysis of the flow field and the index of the speed is fitted.

Abstract: In this paper, the main performances of the lead-acid battery used on in a real off-road vehicle were tested through experiments. The lead-acid battery voltage and current characteristic curves of the self-discharge, real vehicle starting experiment and battery electricity demand experiment performance in the different conditions were studied. The results show that this lead-acid battery can be used as the preferred battery and the charging and discharging rules of this battery can be used to improve the vehicle design.

Abstract: Hierarchically SAPO-11 with meso- and microporosity was prepared from a facile acid assistant dealuminzation procedure. Two kinds of acid with different acid strength were investigated. The results revealed that both the acid could efficiently remove alumina species in zeolite crystal lattice. N₂ adsorption/desorption isotherm and HRTEM images showed the formation of mesoporosity in SAPO-11 after treated with hydrochloric acid but not with citric acid. XRD analysis showed the destruction feature of SAPO-11 was occurred after citric acid treatment.

Abstract: The correlation of Diamond-Like Carbon (DLC) bonding structure versus film corrosion protective capability against Hydrofluoric (HF) acid exposure was made. Raman analysis of DLC films that were subjected to repeated thermal cycle heating showed that were more clustering in sp² sites upon exposure to high temperature and increasing time. When these films were subsequently exposed to HF acid, there was also corresponding increase in the amount of pitting corrosion features. The increase in sp² clustering size is seen as a weak point in the overall DLC structure which subsequently allowed the acid to penetrate the film structure.

Abstract: The influence of NCO/OH ratio of PU monomers on the thermal, mechanical and chemical properties of palm-based polyurethane (PU) was investigated. The prepolymerization of PU was conducted at NCO/OH ratio of palm kernel oil polyol (PKO-p) to 2,4-methylene diphenyl diisocyanate (MDI) at 200/100, 150/100, 100/100 and 75/100 with diethylene glycol (DEG) as chain extender at ambient temperature under nitrogen gas atmosphere. The palm-based PU prepolymer was casted onto a Teflon plate to a thickness of 50 µm. The presence of the urethane linkages (OCN-H) was identified from the FTIR spectrum. The disappearance of NCO peak in the FTIR spectrum at 2270-2250 cm-1 indicated that MDI had completely reacted with the PKO-p to form PU. The appearance of C=O peak at 1700 cm^-1 showed that hydrogen bonds were formed between the soft segmented chain and hard segmented chain which were contributed by PKO-p and MDI respectively. Hence, urethane bond was the main polymeric chain in the PU. Besides, PU with the highest hard segment content (NCO/OH ratio: 200/100) exhibited great thermal stability (T_stable of 205°C). In addition, it showed the highest glass transition temperature (85°C) compared to other PU coating formulations. Endothermic peaks were detected in PU with low NCO/OH ratio of 150/100, 100/100 and 75/100 which was referred to the flash point of the polyols (PKO-p and diethylene glycol). However, PU with the highest content of hard segment possessed the lowest scratch resistance of 0.5 N. Steric effect due to benzene ring in MDI molecular chain caused restriction in the mobility of the PU chain.

Abstract: Activated carbon supported gold nanoparticles (Au/C) were prepared by a chemical reduction process using NaBH₄ as a reducing agent. The characterization of transmission electron microscope indicated that the Au nanoparticles (AuNPs) in the Au/C catalyst were highly well dispersed on the carbon support. The catalytic activity of the Au/C catalyst for the methanol electrooxidation (MEO) was investigated by the cyclic voltammetry (CV). The results displayed that the Au/C catalyst exhibited a favorable catalytic activity towards the MEO in alkaline solution. Moreover, the competitive adsorption between OH^- and CH₃OH on the surface of the AuNPs in the Au/C catalyst existed in the course of the MEO. Based on this competitive adsorption, the mechanism of the MEO on the Au/C catalyst was further investigated.

Abstract: A non-vacuum process for fabrication of polycrystalline CuIn(Se,S)2 (CISS) thin films with chalcopyrite structure were synthesized by sol-gel spin-coating method using nitrates as precursor for low-cost photovoltaic applications. Sequential reduction, selenization and sulfurization treatments were performed with hydrogen, Se and H2S vapor, respectively. X-ray diffraction (XRD), SEM and EDS analysis have been employed to examine the structural properties, surface morphology and atomic concentrations of polycrystalline CISS thin films. The experimental results demonstrated that the obtained CISS had good crystallinity, uniformity and near stoichiometric composition.