Advanced Materials Research Vols. 160-162

Abstract: Through INSTRON1304 electric hydraulic servo fatigue testing machine, the fatigue experiment of soil-cement is done, and the ultrasonic velocity of soil-cement under dynamic loading is obtained. The results show the ultrasonic wave velocity through the cemented soil samples free surface obviously attenuates as the cycles of the dynamic loading increases. Based on the damage variable defined by the ultrasonic wave velocity, the evolution equation of soil-cement accumulated fatigue damage is established. The equation indicates that the fatigue damage of soil-cement l under dynamic loading can obviously be divided into three stages: the initial rapid decay of the initial state, stability decay and rapid damage close to the destruction. The experiment results provide an important reference for non-destructive testing of soil-cement under dynamic loading.

Abstract: Based on the microscopic phase-field model, the precipitation process of Ni75Al4.3V20.7 alloy at 1190K is simulated, and the kinetics of order-disorder transition at antiphase domain boundary (APDB) formed between DO22 (Ni3V) phases is investigated. After the ordered APDB formed by the impingement of growing DO22 (Ni3V) domains, the order-disorder transition at APDB is happened. Accompanied with the enrichment of Ni and Al at the APDB, the ordered APDB transforms into a thin disordered phase layer. The second phase L12 nucleates at the order-disorder interface between DO22 and disordered phases, and grows along the disorder phase layer quickly. The order-disorder transition at the ordered APDB accelerates the nucleation and growth of L12 phase at the APDB. The disordered phase caused by the order-disordered transition can be considered the transient phase during the precipitation process of L12 phase.

Abstract: Knowledge of damage distribution is important and essential for understanding the dynamic failure behavior of solid material under the high velocity impact. For the High Purity Aluminum (99.999%), disk sample was shock impacted by a light gun and its damage distribution has been carefully characterized. The recovered sample was cut symmetrically along the impact direction and the damage on the cross section has been statistically studied. Unlike the previous work as Lynn Seaman et al. reported, a new computation treatment has been established in terms of the Schwartz-Saltykov method, which gives an easy and simple transformation from the two-dimensional size distribution to three-dimensional size distribution. We demonstrated the variation of damage distribution of High Purity Aluminum under different dynamic tensile loading, and discussed the damage evolution characteristics associated with the micro-voids nucleation, growth and coalescence. Results provide physical basis for the theoretical modeling and numerical simulation of spall fracture.

Abstract: We report the synthesis of single-crystalline α-Fe2O3 nanoflakes by the oxidation reaction of water vapor through a gas-solid method. The samples are characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), micro-Raman spectrometer, and transmission electron microscopy (TEM). As-synthesized nanoflakes have a pseudotriangle morphology: 20-50 nm in thickness, 0.5-1.5 μm in length and base-width. It is observed that vertically aligned arrays of leaf-like α-Fe2O3 grow at the verges of the iron foils. The possible mechanism is discussed to elucidate the formation of α-Fe2O3 nanostructures. The experimental results indicate that water vapor plays an important role in controlling the morphology of the final products.

Abstract: Polycrystalline magnetite (Fe3O4) thin films is synthesized at low temperature (90 oC) by electroless plating in aqueous solution, and the behavior of the magnetic property of the Fe3O4 thin film irradiated by Kr26+ ions at energy of 2.03 GeV is investigated by magnetization measurements. The initial crystallographic structure of the Fe3O4 remains unaffected after swift heavy ion (SHI) irradiation, but both coercive force and saturation magnetization are sensitive to Kr26+ ion irradiation and exhibit different behaviors depending on the ion fluence range. And SHI irradiation could make the magnetic moments of the Fe3O4 films ordered around the columnar defects and the magnetic moments tend to arrange along the films plane. All modifications of the magnetic properties could be interpreted very well by the effects related to the stress and defects induced by SHI irradiation.

Abstract: In order to study on mechanical character and damage mechanism of the concrete under different loading conditions, the uniaxial and biaxial compression experiment of concrete is investigated by Isotropic Biaxial Loading System of Henan Polytechnic University. The experimental results show the damage of the concrete under uniaxial compression is shear damage, however the damage of the concrete under biaxial compression is tension-shear damage; biaxial compression stress-strain curves of concrete are similar with those of concrete and can equally be divided into three stage; as the result of the intermediate principal stress, 1:1 biaxial compression strength increased 56.12% and 13.30% than that under 2:1 biaxial compression and uniaxial compression, at the same time 2:1 biaxial compression strength increased 37.80 % than that of the uniaxial compression.

Abstract: The armed steel target impacted vertically by tungsten spheres with different initial velocities and masses was studied by experiments. The macroscopic properties of crater were analyzed by the shape features of crater, the size dimension of crater, cracks along the penetration tunnel and the characteristics of recovered tungsten spheres. The results show that the everted rimmed and irregular shape of crater is heavier with velocity and mass of tungsten sphere. The shape of the top surface of impactor changes from the original sphere to the flat profile and the mass shows an obvious drop at a higher impact velocity The ratio of the crater diameter to the diameter of tungsten sphere, and the ratio of the crater depth to the crater diameter both descend with the mass at the same initial velocity of tungsten sphere. The specific expression of nondimensional penetration depth versus dynamic pressure is given by experiment data.

Abstract: Porous carbons have been prepared by a template-like method using non-porous pumice mineral as a “template”, and sucrose and furfuralcohol as carbon sources. Nitrogen adsorption and scanning electric microscope (SEM) have been used to investigate the pore structure and morphology of the samples. The study results indicate that the surface areas of the carbons prepared from sucrose and furfuralcohol are 208 and 268 m2/g, respectively. The carbon prepared from sucrose is microporous, and the carbon prepared from furfuralcohol is a carbon with both micropores and mesopores.

Abstract: Wood drying is one of the most important process links in wood products processing and it consumes roughly 40%~70% of the total energy in the entire process. The performance of a mobile wood solar drying device with latent heat storage system was tested in this paper. The test results showed that the average power of collector system was 0.572kW and thermal efficiency was 56%, which was higher than that of the flat-plate collector. Energy storage efficiency came to 66% and energy storage density was 54.5 MJ/m3. Compared with the steam drying, energy-saving effect of solar drying increased significantly. The energy saving rate was 71.2%. Additionally, the drying device could accurately control the temperature, so it could better accomplish various drying process.

Abstract: Tobermorite nano-scale powder was synthesized from potassium feldspar ore from Henan province Lushi country in China. In the present research work, its adsorption property to Cd2+ was studied. The factors of adsorption such as pH values, traction time, initial concentration, and temperature were studied. The adsorption equation was curvefitted by the Langmuir and Freundlich adsorption isotherm and the thermodynamics adsorption was analyzed. By the orthogonal experiment and single-factor experiment of the adsorption, the optimized conditions of the adsorption for Cd2+ were achieved: the reaction temperature is 40°C, the reaction time is 20 min, the initial concentration of aqueous solution is 20 mg•L-1 and pH value is 6.0. Under these conditions the adsorption efficiency of Cd2+ can reach 99.89%. The orthogonal experimental results show that the order of effect on adsorption efficiency was the initial concentration, pH value, reaction temperature, reaction time. In different temperatures, the results show that isothermal Langmuir equation can describe the isothermal adsorption characteristics of Cd2+ on tobermorite. Thermodynamic parameters can be drawn: the G was negative and with increasing temperature H increased, so the adsorption process is a spontaneous reaction to the heat.