Applied Mechanics and Materials Vol. 775

Abstract: Based on the modified polylactic acid modified calcium carbonate, calcium carbonate in later polylactic acid blend will form a network structure in the composite material, effective to prevent the expansion of micro cracks, secondly, between the modified calcium carbonate will produce the corresponding yield, so that the modified calcium carbonate structure between plastic deformation, can impact absorbing energy, effective therefore, calcium carbonate particles exist, can effectively make the extension of small cracks in composite materials by passivation. Adding modified calcium carbonate composite materials, improve the crystallinity and composite heat resistance, but also reduces the cost of poly lactic acid and anti impact performance, its application field has been widely extended.

Abstract: Influence of various reducers of tungsten from a scheelite concentrate on a complex alloying of melted low-carbonaceous steel by tungsten through oxides slag system is investigated. By electroslag remelting of low-carbon steel with use of ceramic gumboils on the basis of mineral associations are received high-alloyed by tungsten (to 20 wt.%) became.

Abstract: In order to better understand the morphology and properties of polymer nanocomposites it is necessary to conduct their characterization by Transmission Electron Microscopy (TEM). This work shows a technique through which the nanocomposite powder is mixed with a resin, and after cured, thin sections can be obtained by ultramicrotomy. Another technique presented in this work deals with the observation of clay powder in solution. In this work High Resolution Electron Microscopy (HRTEM) was used to obtain images of the nanocomposites and clay. Images with a high level of details were showed. Through the use of such techniques, it was possible to observe two types of clay morphology in polymer matrix and its distribution. The dimensions and hexagonal layers of the natural clay used as nanofiller for the nanocomposite were also observed. The X-ray Diffraction (XRD) was used to investigate the kaolinite and nanocomposite.

Abstract: The oxidation of Ti₃Al_0.7Si_0.3C₂ carbide at 1100 and 1200°C in air for up to 50 h resulted in the formation of rutile-TiO₂, α-Al₂O₃ and SiO₂. Depending on the location of the carbide, either thin, dense, single layered oxide scales or thick, porous, bi-layered oxide scales formed. The single layered scales consisted primarily of protective Al₂O₃. The bi-layered scale consisted primarily of an outer (TiO₂+Al₂O₃)-mixed oxides, and an inner TiO₂-rich, (Al₂O₃+SiO₂)-containing oxides. Since the testing temperatures were high, the oxidation rates varied much depending on the location of the carbide.

Abstract: Cathodic hydrogen was produced in the presence of anaerobic zero valent iron (ZVI) corrosion by water. It can enhance microbial denitrification to convert nitrate to N₂O and N₂. Autotrophic denitrifying growth on ZVI can enhance nitrate removal. Results showed that by increasing nitrate removal rates, innocuous gases (N₂O and N₂) are produced rather than ammonium. Using steel wool with a small specific surface area instead of powdered ZVI, pH was not significantly increased. Little pH change was caused by corrosion. This is a positive condition for autotrophic denitrifying bacteria. ZVI was used in permeable reactive barriers (PRBs) process under anaerobic conditions. It used sulfate reducing bacteria for immobilization of heavy metals. In fermentation, methanogenesis and sulfate reduction was complete after adding ZVI to mixed anaerobic cultures. It was found that methane production increased and sulfate was reduced. This was due to readily utilizable ZVI which served as a slow-release electron donor for methanogenesis and sulfate reduction. ZVI has potential as a useful material in bioremediation.

Abstract: The solubility of L-proline in binary solvents of methanol and dichloromethane were measured by a dynamic method via a laser monitoring technique. In the binary solvent mixtures, the solubility increases with the increasing of temperature and proportion of the methanol. The experimental solubility were fitted to modified Apelblat equation and Van’t Hoff equation in this work can be used as essential data and models in the purification process of L-proline. The dissolving process is endothermic and the dissolution driving force converts from enthalpy-driving to entropy-driving.

Abstract: Using first principles approach, we present the structural, vibrational and dielectric properties of α-SiO₂. The calculations have been carried out within the density functional perturbation theory and linear response formalism using the norm-concerving pseudopotentials and a plane wave basis. All the vibrational modes identified are in good agreement with experiment. The calculated infrared spectra are also in good agreement with available experimental results both for the positions and the intensities of the main peaks. We find that the modes Eu7 and A2u4 splits in two respectively at high hydrostaticpressures. Then we calculate the infrared spectra under high pressure of different orientations. The vibrational modes in different phase transitions are reported and discussed respectively.

Abstract: This paper deals with the determination of residual stress in SiC adherend bonded with inorganic phosphate adhesive using Raman and fluorescence spectroscopy in a micro-Raman system. To determine the stress mode in the specimen, we descript the corresponding relation between the Raman effect and residual stress. The laser with wavelength at 532nm and 785nm was respectively applied to test hundreds of test points on the SiC adherend and selected 785nm wavelength laser as the illuminant. Meanwhile, Raman imaging was used to analyze the surface of SiC and inorganic phosphate adhesive. Meanwhile, we determined the unreliability of estimating by Si peak. Taking E₂-TO peak as reference, residual stress of six selected points was obtained. Then, we summarized the mechanism of compressive stress, and analyzed the stress change regulation.

Abstract: In this paper, the technology, equipment and method used to m easure the mechanical properties of micro-scale new-style intelligent shape memory alloy material were studied. First, two groups of small-scale shape memory alloy samples were made and the suitable micro load device was designed according to samples’ size and force range. Then the strain of the samples were observed with the video microscopy and calculated. Comparing with the corresponding force, the stress-strain curves of the two groups of samples were obtained respectively. After fitting these two curves, the stress-strain curve of the sample material was obtained. Finally, the basic mechanical properties of this shape memory alloy materials were discussed.

Abstract: During selective laser sintering process, different sintering parameters have great impact on the performance of the molded parts, and the degree of influence is different. Using orthogonal test, indirect sintered 316L stainless steel, the compressive strength and precision of the parts were measured and compared to study the influence of various sintering parameters (laser power, scanning speed, scan spacing, preheating temperature) on sintering. The greater degree of influence factors were got by range analysis. The results show that laser power, scanning speed and scan spacing have greater degree of influence on the compressive strength of the parts, and the preheating temperature have less impact. By comparison, the optimum set of parameters was concluded: the laser power is 15W, the scanning speed is 1900mm/s, the scan spacing is 0.125mm, and the preheating temperature is 60°C.