Applied Mechanics and Materials Vols. 84-85

Abstract: Fluorocarbon coatings were deposited on the surface of regenerated cellulose films by RF magnetron sputtering, using polytetrafluoroethylene targets. Argon was used as the working gas. The coatings were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, atomic force microscopy, and static contact angle and oxygen permeability measurements. It was found that the coatings were made up of the four components -CF3, -CF2-, -CF- and -C-. The [F]/[C] ratio varied with sputtering conditions. The static contact angle of the coatings was greater than 90° at lower power and higher pressure, and the substrate material was transformed from hydrophilic to hydrophobic character. The fluorocarbon coatings were porous and did not influence the oxygen permeability of the cellulose film substrates.

Abstract: A type of porous material was prepared mainly using iron tailings and shale, adding foaming agent, fusing agent and flexibility agent. To determine the sintering system of porous materials basing on iron tailing and shale, the effect of sintering temperature on the microstructure of the samples was investigated by XRD and SEM as well as section topography. The results indicate that both the porosity and pore size of the samples become higher and bigger respectively as sintering temperature increases from 1100°C to 1130°C, while mineral phase anorthite decreases; when sintered at 1120°C, the size of pores is approximately the same with the mean pore size of 1.5mm; the pores are larger and some get connected to the adjacent pores when the sintering temperature increases to 1130°C.

Abstract: Mg-xZr damping alloys (x=0.6, 1.5, 2.5, 5, mass %) were prepared by PM (powder metallurgy ) technology, and effects of Zr contents on microstructure, mechanical properties and damping capacities of Mg-xZr damping alloys were researched by three-point bending test and DMA, etc. The results show that the microstructure become into strip-shaped morphology, more granular particles appear in the grain boundaries or inside grains, and the grains are more refined with the increase of Zr additions. Micro-hardness and bending strength of the Mg-xZr damping alloys increase with increasing addition of Zr, and reach the maximum value with Zr addition of 2.5%. The damping capacities of Mg-xZr alloys increase slowly with the temperature from 27°C to 100°C, and increase rapidly above 100°C. The damping peaks appear at temperature of 160°C. Mg-5％Zr alloy exhibits the highest damping capacity, and its tanf value reaches to 0.084. The temperature of the damping peak increases with increasing frequencies, showing the characteristic of relaxation damping.

Abstract: Mullite/corundum composites synthetized by sintering with bauxite as raw material was researched. The sintering temperature, main crystal phase, microstructure and fracture mode of the composites synthetized by sintering are different with change of ratio of Al₂O₃ and SiO₂ and content of Al₂O₃: (1) If the ratio of Al₂O₃ and SiO₂ and content of Al₂O₃ is low, sintering temperature of the composites is high, the main crystal phase is mullite, microstructure shows interlocking network structure formed by columnar mullite, the fracture mode of composites shows that mullite appears in the pulled out state; (2) If the ratio of Al₂O₃ and SiO₂ content of Al₂O₃ is high, sintering temperature of the composites is low, the main crystal phase is corundum, microstructure shows the skeleton structure formed by granulous corundumthe, the fracture mode of composites shows intergranular fracture formed by corundum, occasionally transcrystalline fracture. The major reason of different sintering temperature of the composites is concerned with mullitization degree and content of glass phase.

Abstract: Long afterglow phosphor is a special energy-saving material, which can store the energy of light irradiation and release light slowly. Ultrafine aluminate long afterglow phosphor is commonly prepared by the jet milling method. This method results in weak brightness, which restricts its application in delicate printing or textiles. In this study, fine particle aluminate phosphor (5μm) was coated by alumina, and then re-reduced under a high temperature. The alumina film works as a barrier layer, which protects the particles from sintering. The re-reduced phosphor had double afterglow brightness, and the size of the particle retained original level. The influences of pH value and KOH adding speed were investigated, the optimized parameters are: pH = 5, KOH adding speed = 2 ml/min.

Abstract: According to the important status and practical values of geographical factors and genetic factors in protein content estimation of winter wheat, a method analyzing the relationship between factors and protein content was proposed in this paper. In the method, genetic, geographical factors were chosen as independent variables, multivariate nonlinear regression model was introduced to estimate protein content. Firstly, construct one-dimensional nonlinear regression model based on each factor. Secondly, analyze and select sensitive factors on basis of the above simulations. Finally, couple the selected sensitive factors into multivariate nonlinear regression model for protein content estimation. Winter wheat was chosen as experimental subject. The results showed that, at province scale and county scale, the proposed method could not only effectively improve simulation efficiency, but also enhance whole estimation accuracy.

Abstract: 3-layer anodic bonding is one of the key technologies in the manufacture of complicated structure. The microcosmic process and current model of the 3-layer anodic bonding was investigated, and a new technology scheme with better bonding effect was developed. Using the experiment device, quantities of bonding current curves were obtained by the data collecting system. Under tensile testing device, intensity of the bonding was tested. By analysis of the data collected, the 3-layer bonding model was inspected, and the efficacy of the new technology scheme was proved.

Abstract: Influence of the pulse currents, the pulse frequency and CoSO₄ content of plating solution on Co content of Ni-Co alloy coatings are investigated by environmental scanning electronic microscopy and field emission scanning electronic microscope. The result shows that Co content of Ni-Co alloy coating increases as the increase of CoSO₄ content and pulse frequency. Co content of Ni-Co alloy coating increases when the current density decrease. When CoSO₄ content of plating solution and the pulse frequency increase, the coating surface become smoother, microstructure become denser and coating grain refinement. when current density is small, coating crystalline grains size are tiny and the coating crystalline grains arrangement is relatively close. In the Ni-Co electrodepositing process, the combining of Ni²⁺ and Co²⁺ generates [CoNi (Ⅱ)] intermediate products, then the decomposion of [CoNi (Ⅱ)] generate Co and Ni²⁺. This hinders sedimentation of Ni²⁺ ions and increases sedimentary speed of Co²⁺ ion. Polarization of electrodeposited cobalt is lager than polarization of electrodeposited nickel. So as the current density increases, nickel deposition relative faster than cobalt, thus leads to the cobalt content of coating decreased. The recovering frequency of metal ion concentration in pulse spread layer rise at the fixed time as pulse frequency increases.

Abstract: This paper investigates numerically the motion and deposition behaviors of micro- or nano-scaled particles in fluid passing three different kinds of square pores. The three kinds of square pores represent different pore structures in porous medium. The flow fields are numerically simulated by lattice Boltzmann method (LBM). The computation procedure code was validated by comparing the results with those of the previous works for the case of particle fluid passing a square block in a two dimensional channel flow. The results show that the dispersion of particles in three different square pore structures are much different, and vary with Stokes numbers for the same square pore even the Reynolds numbers are the same. In addition, the number and the position of deposited particles are analyzed. It shows that the deposition characteristics of each wall are mainly influenced by Stokes number, Reynolds number and the pore structure.

Abstract: Curriculum, teaching methods, clinical practice ability, dissertations and assessment methods were investigated to discuss and analyze the present cultivating situation and its problems of clinical professional degree graduates in order to provide the basis for reform of cultivation modes. Methods: Clinical professional degree graduates, supervisors, training institutions and employing units were treated with sample surveys, interviews and literature research. All the data were dealt with statistical analysis. Results: The cultivation mode of clinical professional degree graduates has been constructed gradually. But there still existed some difficulties and problems in terms of course construction, cultivation methods and assessment system and so on, which were needed to be strengthened.