Applied Mechanics and Materials Vols. 347-350

Abstract: Elastic constants of purity and containing impurity metal aluminum were calculated, and the effects of impurity on the elastic constants were also studied. The effect of particle on micro-stress concentration and debonded stress of inclusion was researched. The mechanical relationship between the grains was defined by relationship of displacement and driving force in cohesion zone model (CZM).The method can be extended to research mechanical properties of other metals and alloys structures.

Abstract: Recently, graphene has attracted a lot of attention and made great progress in material and device preparation. This paper highlights the progress in graphene material and device preparation. In material preparation, we compare some different methods and deduce the better methods; In device design, we mainly discuss the new ways to the problem of graphene based transistors, that is the small current on/off ratio. At last, we mention some important developments of graphene.

Abstract: Micro-nanoTiB₂ ceramic was prepared through increasing the molar ratio of Mg and leaching with suitable acid by the combustion synthesis reaction of Mg, TiO₂ and B₂O₃, which could get higher temperature and purer product. The Samples were investigated by XRD and SEM, and the results showed the diameter of the TiB₂ was 200 nm ~ 300 nm and the shape of the TiB₂ was irregular hexagonal crystal. The diameter of the TiB₂ was decreased with the increase of Mg powder. The formation mechanism of TiB₂ has been studied.

Abstract: In order to increase the failure temperature of Zr-N diffusion barrier for Cu, the effect of insertion of a thin Zr layer into Zr-N film on Zr-N diffusion barrier performance in Cu metallization was investigated by means of X-ray diffraction, scanning electron microscopy, Auger electron spectroscopy, and 4-point probe technique. XRD,SEM ,AES and FPP results show that the insertion of a thin Zr layer into Zr-N film improves barrier properties significantly when the ZrN / Zr/ZrN barrier layers are deposited by RF reactive magnetron sputtering and Zr-N(10nm)/Zr (5nm)/Zr-N(10nm) barrier tolerates annealing at 700°C for 1 h without any breaking and agglomerating Cu film. This interpretes that insertion of a thin Zr layer into Zr-N film is attributed to the densification of grain boundaries in ZrN/Zr/ZrN films followed by the reduction of fast diffusion of Cu through ZrN /Zr/ ZrN multilayered films.

Abstract: Based on the analysis of now available evaluation indexes to estimate the formability of Variable cross-section Y-shaped tube hydroforming, an aggregative indicator is proposed. The effect of load path on the formability of Variable cross-section Y-shaped tube is discussed by FEM simulation, and validity of the evaluation index and simulations are proved by experiment. Results show that with the broken line load path of 0-30-30-40, the value of aggregative indicator is the greatest and the formability is the best. The optional parameters are testified by experiment and the results are in agreement with the FEM simulation results.

Abstract: SiC/Fe composite was prepared using electromagnetic stirring approach. The distribution of SiC particles in steel matrix was affected, in a different manner, by stirring power and stirring time in three test particle addition methods. When particles were blown from bottom of molten steel by airflow, the dispersion coefficient of particles was lower with reduced stirring power and prolonged stirring time. In contrast, when particles were dispersed directly by funnel or injected a block premade by particles and a small amount of matrix, the particle dispersion coefficient was increased following the decrease of stirring power or stirring time. This study provided a guidance of how to achieve a more uniform distribution of SiC particles in steel matrix.

Abstract: Moldflow software was used to obtain the best gate location and count. Influence of injection molding processing parameters on sink marks of injection-piece was studied based on orthogonal test. The effects of different process parameters were analyzed and better process parameters were obtained. Results of research show that decreasing melt temperature, mold temperature, the increasing injection time and packing pressure can effectively reduce the sink marks index.

Abstract: The physical model of the flame of gunpowder composite welding rod (GCWR) is built based on the flame topography and the combustion mechanism of thermite. The chemical reactions in different flame regions are fixed with the physical model, combustion characteristics of thermite and gunpowder combustion theory.

Abstract: The transverse properties were inferior to the longitudinal properties for the existence of banded structure in 20G steel. In order to eliminate the banded structure and improve the transverse performance of 20G steel, different heat treatment processes were adopted. The results showed that conventional normalizing could reduce the banded structure and refine the grain sizes. When 20G was heated with 10°C/min heating rated and then held at 920°C for 2h, the banded structure in the steel was almost eliminated and the microstructure was homogeneous with fine grain size, the strength increased by 14%. The non-metallic inclusion and carbide in the microstructure leaded to stress concentration and separation with the base metal. To some extent, heat treatment can improve the distribution and form of non-metallic inclusions.

Abstract: The cross-linked polyethylene cable is largely used in power-supply system of the city. As the length of the power cable is concerned with the technology and construction, the center joint is largely employed, and the fault of the power cable is often found in the center joint. The discharge light has been seen on the face of the XPLE-SIR in work. The carbonization granule which appears after the discharge is the primary cause of the insulation degradation. A sample is designed, and the alternate electric-field rise on it to imitate the operational aspect. This paper analyses the relation of the discharge light, discharge current and carbonization granule. We find that it is feasible according to study the interface discharge light to deduce the characteristic of discharge and carbonization granule, and judge the degree of the interface insulation degradation.