Advanced Materials Research Vols. 765-767

Abstract: The corrosion behavior of rebar HPB235 in 1.5wt.% NaCl solution was studied and its mechanical properties were tested before and after corrosion. The results showed that, with corrosion time increasing from 240h to 720h, the corrosion rate increases and the corrosion becomes heavier and heavier. After 720h, the yield strength, tensile strength and elongation are decreased by different extent.

Abstract: In order to make a more intuitive and easier analysis the influence of different inclusions on the formation of ferrite, a layer of high purity oxide powder was added in the two parts of the Q235 steel artificially. The effect of the inclusions Ti₂O₃MgOZrO₂ and Al₂O₃ on the nucleation of intragranular ferrite were studied by means of the physical simulation method. The microstructure of the micro-zone adjacent to the inclusions was observed and the elements of the micro-zone adjacent were analyzed. The results showed that the inclusions Ti₂O₃ and Al₂O₃ can form the ferrite layers at the oxides-steels interface; the inclusions Ti₂O₃ has an ability to induce the nucleation of intragranular ferrite; the inclusions Ti₂O₃ can change the chemical composition of the metal micro-zone adjacent to the inclusions, where the Mn depletion area was observed.

Abstract: Flyash is the ash collected from chimney of coal-fired power plant. According to statistics, 70% of coal production in our country is used for thermal power generation. One ton of flyash would be produced as long as power plant uses 4 tons of coal. Annual emission of flyash has surpassed 100 million tons. It is predicted that it may be 150 to 260 million tons per year up until Year 2000 to Year 2013. Huge number of emission of flyash covers a mass of farmlands and water resources. Ash disposal area of thermal power plant cannot afford the increasing number of flyash and its storage capacity is in an emergency in which ash disposal area is being extended or newly constructed with a massive amount of money. Therefore effective, universal and vast use of flyash is of profound significance for reducing the environment load and saving limited construction fund. This paper researches the beneficial effects of flyash on concrete property.

Abstract: Four high-entropy alloys are prepared by an arc furnace under argon atmosphere. The microstructure and the properties of the alloys are investigated. The results show that NiCrCuCoFe alloy consists of a single FCC solid solution. When Al presents in the alloys, the microstructures of the alloys change to a BCC+ FCC solid solution. It is indicated that Al element promotes the formation of BCC solid solution, and Si and Mn promote the formation of complicated compounds. The hardness of alloys with BCC structure is higher than that of the alloys with FCC structure. The complicated compounds are formed, the hardness increases further. The highest hardness of the alloys reaches 882 HV due to the strengthening of the second phase precipitation.

Abstract: Considering the geometric and material coupling of a composite wing, the equations of motion are derived based on Hamilton theory. Frequencies computing and validation of a composite wing with bending-torsion coupling using differential quadrature method (DQM). And the DQM is applied to the flutter speed solution of a composite wing. The results thus obtained are then compared with some available results and a good agreement is observed. The computing time of DQM is highly improved compared with Galerkin method. Moreover, the effect of material coupling rigidity on flutter speed is analyzed and this is important to the design of composite wings.

Abstract: As most of sedimentary rocks are anisotropic, it is significant to research the impact of the anisotropy of strength on wellbore stability in drilling engineering. Particularly, in the Kuqa piedmont exploration area, the anisotropy of strength caused by various jointed surfaces, fracture surfaces and fault planes in formation cause the formation of several groups of weak low-intensity planes traversing borehole . These weak planes will become failure earlier than the rock body in the context of strong stress and high pore pressure, causing chipping, breakouts and sticking. If fractures have good permeability and drilling fluid column pressure is greater than pore pressure, loss may occur. The loss pressure would not be controlled by fracturing pressure and horizontal minimum principal stress, but it depends on the relationship between fracture occurrence and triaxial stress state. In the event of loss, the drilling fluid will flow into these weak structural planes, causing the decrease of friction between rocks and increase of wellbore instability. As a result, for strongly anisotropic formation, the collapse pressure and leakage pressure of weak planes are key factors for evaluating well drilling stability. In this study, according to the stability evaluation on the transversely isotropic rock mechanics in Keshen zone of Kuqa piedmont, the impacts of fracture development on wellbore instability is analyzed; relevant suggestions on engineering geology for the special pressure window in strong anisotropic formation are also put forward.

Abstract: Tests of bird strike have been carried out on plate made from LY-12 Aluminium. The test was down with the projectile impacting the target perpendicularly at velocity of 40m/s, 80m/s, 120m/s respectively. The displacement-time history curves and strain-time history curves of on LY-12 Aluminium plate were measured. The good agreement of the results between two specimens in one group indicated that the results tested in the presnet paper are reliable. The dynamic response of the plate and damage modes of the bird influenced by striking velocity were analyzed. The peak value of the displacement linear enlarged with the increasing of the striking velocity. The test results in the present paper provided valuable data for aircraft design impacted by bird, and also provided abundant test datas for the numerical simulation model applied in bird striking.

Abstract: The monodispersion situation of Multi-walled carbon nanotube dispersion is vital for fabricating high quality MWCNT buckypapers with vacuum filtration method. In this paper, the MWCNT buckypapers were fabricated by surfactants Triton-X100, sonication, centrifugation, vacuum filtration, rinsing and annealing processes. Transmission electron microscopy (TEM) and Zeta potential results show the maximum achievable separation has been reached. The properties of MWCNTs buckypaper can be characterized by Scanning electron microscopy (SEM), a four-point probe, N₂ adsorption isotherm, TGA-DSC methods. The results showed that the buckypaper exhibits a low surface and volume density, a high porosity and electric conductivity. The pore diameter is up to 22.02nm, no substantial mass loss below 600°C in air.

Abstract: The perturbed-chain statistical associating fluid theory (PC-SAFT) and density-gradient theory (DGT) were used to construct an equation of state (EOS) for the bulk and interfacial properties of monoethanolamine (MEA) and its aqueous solutions. The molecular parameters and influence parameter were regressed by fitting the experimental data of phase equilibria and surface tensions. With the molecular parameters and influence parameter as input, the surface tensions of MEA aqueous solutions were correlated satisfactorily.

Abstract: The influence factors of hydrothermal treatment on the formation process of ZnO nanorods are investigated involving with hydrothermal temperature, time and precursor concentration. The as-obtained products were characterized by Scanning Electron microscope (SEM) and X-ray diffraction (XRD), respectively. XRD result indicates that the obtained ZnO nanorods are high-quality single crystals. SEM results indicate that both the diameter and the length of ZnO nanorods increase with increasing the hydrothermal time and temperature. The precursor concentration prominently determines the morphologies of ZnO nanostructure from initial particle morphology to rod-like, and to final slice-like morphology.