Advanced Materials Research Vols. 415-417

Abstract: The geometric and electronic structures of Cr chains are studied by the first-principles of density-functional method. The present calculation results show that chromium can form planar chains in linear, zigzag, dimer, and ladder form one-dimensional structures. The most stable geometry chain among the studied structures is the ladder-form chain with five nearest neighbors. The dimer structure is found to be more stable than the zigzag one. Further more, the relative structural stability, the electronic energy bands, the density of states is discussed based on the ab initio calculations.

Abstract: Combining the contact elements into the two-scale homogenization method, the effective mechanical properties of nano-composites with a debonding interface are analyzed. A periodic microscopic representative volume element (RVE) is modeled by using a four-phase composite composed of matrix, nano-tube, bonded, and debonding interfaces. The initial stress and coulomb's friction are considered within debonding interface, which is applied to transfer the shear stress produced by the relative slip between nano-tube and matrix, and a simple elastic–plastic constitutive model is established to study the effective mechanical properties of nano-composites. The predicted results show a strong non-linear dependence of the effective mechanical properties on the elastic modulus, volume fraction, debonding length and the ratio of length with thickness of interface.

Abstract: Stable water dispersions of single wall carbon nanotubes (SWCNTs) have important implications for their applications in biomedical and composites field. In this work, a water-soluble optical brightener bearing benzene ring and sodium sulfonate groups was employed as surfactant for SWCNTs in water. The surfactant molecules were absorbed on graphene nanotube surfaces via π-π interaction, Van Der Waals interaction and electrostatic interactions in water under ultrasonic treatment. The functionalized carbon nanotubes were stably dispersed in water for several months without sedimentation. The carbon nanotubes/organic conjugated molecules nanohybrids have potential application in nanocomposites, biomedical engineering, and photovoltaic devices.

Abstract: Investigated AC frequency and the number of coil turns as well as their influence on the magnetic induction effect of rare-earth La modified FeSiB amorphous ribbon. The results show that the magnetic induction effect is increased with the increase of AC frequency and the number of coil turns, and changing amplitude of magnetic induction effect shows first increased and then decreased with increasing frequency and coil turns.

Abstract: The paper discusses the contributing factors of dike failure occurred during construction of the diversion ditch. It is concluded that composition of ground and effect of the groundwater are physical element of slide, soil from ditch excavation placed on the top of flanking slopes for embankment and stress-relief at the foot of flanking slope by excavation are induced factors.

Abstract: The theory of laser milling ceramics was analyzed. Experiments of laser milling were done on Al₂O₃ ceramics with Nd:YAG laser. The influence law on the amounts of laser milling and milling surface quality with different parameters were studied systematically and the micro-morphology of the milling surface was analyzed. The optimal parameters were obtained according to the experimental results.

Abstract: In this paper, we make systematical investigation for the new synthesis pathway of AACH multilayered nanofiber, which has been prepared by a low-temperature solid-state reaction. The phase transformation sequence of AACH on heating is found that the precursor converts into γ-Al₂O₃ at 700-900°C and elevated temperature results in the θ-Al₂O₃ and α- Al₂O₃ crystal phase formation at 1000°C. With a higher calcination temperature at 1100°C, α- Al₂O₃ pattern appears. The specific surface area (SBET) of aluminum oxide specie calcined at 500°C for 4h is still in 420.2m²/g. Meanwhile, it suggests a partial change in particle sizes and morphology of sample calcined at 500°C for 4h.

Abstract: Using ammonia solution and tin chloride as the precursors: tin oxide nanoparticles with different particle sizes and morphologies were synthesised by varying the concentration, heating temperature and ripening time via hydrothermal method. The particles synthesised were characterised by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The TEM micrographs show that rod-like nanoparticles were synthesised when the SnCl4 solution concentration was less than 1.0 mol/L, which was changed to oval shape when the concentration increased above 2.0 mol/L. Polygonal shaped nanoparticles were observed at 220 °C for 48 hours. It was also found that changing temperature had little effect on the morphology but great influence on the size of the particles, which increased from 10 nm to 120 nm from 160 °C to 220 °C and 12 nm to 55 nm from 6 h to 48 h at 200 °C, respectively. XRD patterns indicated that all of nanoparticles synthesised were tin oxide.

Abstract: In this article, the rationality to determine the mechanical design of the test rig for the beveloid gear with intersecting axes has been verified, and the overall performance of the test rig has been predicted. First, the three-dimensional solid models of all components have been established, and the virtual prototype simulation technology has been used for its kinematics simulation. Then, the static and dynamic performance of the key components has been analyzed. At last, the transfer matrix method has been used to analyze the torsional vibration mechanics of the closed gear test rig, so as to obtain the simulation curves of dynamic load factors of the test gear under different speeds. The results show that the whole test rig can be applied in the gear test with intersecting axes, without the auxiliary test gear pair, which has good gearing test accuracy. Besides, the test rig itself has low costs and good running economy.

Abstract: To improve the self-sharpening ability and increase clearance for debris of metal bonded diamond grinding wheel, the porosity structure is applied to the diamond grinding wheel in this paper. By selecting different inducers diamond composites are burned under appropriate agglomeration condition. The experiment results indicate that diamond composites obtained through two certain inducers can meet both the demand of pore-creating and intensity, so can be used to make wheels. This conclusion lays a foundation for further study.