Advanced Materials Research Vols. 581-582

Abstract: In this paper, the thermoelastic problem of low-dimensional nano copper rod under thermal shock is simulated using molecular dynamics method by adopting embedded atom method potential function. The rod oriented along x-axis, the left edge of the rod is traction free and the right edge is fixed, free boundary condition is imposed on y and z-axis. At the same time, the left and right ends of the rod are imposed hot and cold bath respectively. By virtue of the molecular dynamics method, the temperature, displacement and stress along the rod at different moment are got. The results show that the temperature, displacement and stress distribution in the mobile region are limited, indicating that the heat propagation speed is limited rather than infinite. In addition, the simulation process are conducted the Large-scale Atomic / Molecular Massively Parallel simulator (LAMMPS) and completed visualization software (Atomeye) in this paper.

Abstract: In order to research the formation and spread of adiabatic shear bands in Ti-6Al-4V targets, LS-DYNA code is used to simulate the ballistic impact process. The projectile used in the impact test is a flat-headed steel cylinder with diameter of 7.62mm and length of 39mm. The results of simulated and impact test are in good agreement. Multiple adiabatic shear bands form in Ti-6Al-4V targets under high-speed ballistic impact. Adiabatic shear bands were found to extend parallel with a certain distance. The formation and distribution of adiabatic shear bands was related to the breaking-off of projectiles, which was caused by the distribution of maximum shear stress in Ti-6Al-4V targets and projectiles.

Abstract: In this work, two functional azobenzene-containing metal complexes with different substituted groups have been synthesized and their photoisomerization have also been investigated. It has been found that depending on different substituted groups, the formed azobenzene derivatives showed different properties, indicating distinct regulation of molecular skeletons. Spectral data confirmed commonly the characteristic absorption of substituted groups and aromatic segments in molecular structures. Thermal analysis demonstrated that the structural influence of both compounds in different temperature ranges. The difference of thermal stability is mainly attributed to the formation of Schiff base group and different substituent groups in molecular structure. The photoisomerization of these compounds both in solution and in cast film can undergo trans-to-cis isomerization by UV light irradiation, depending on different substituted groups. The present results have demonstrated that the special properties of azobenzene derivatives can be effectively turned by modifying molecular structures of objective compounds with proper substituted groups, which show potential application in sensor and functional material field.

Abstract: The ferrimagnetic glass-ceramic based on SrO-Na2O-Fe2O3-P2O5-SiO2 system was prepared for hyperthermia application using aqueous aolution-melt method. Using the aqueous solution solvent evaporation, we obtained the molecular-scale homogenously glass precursor. The precursor was completely melted in a lidded platinum crucible placed in an electric furnace at 1480°C for 1h and then annealed in a furnace at 550°C for 40min.The annealed glasses were heat treated at 1050°C for 2h to obtain the glass-ceramics. The crystallization of the glass systems with different component has been systematically investigated by using XRD. Room temperature magnetic property of the samples were investigated using a Vibrating Sample Magnetometer(VSM). The evolution of magnetic properties in these glasses as a function of P2O5 quality concentration was discussed.

Abstract: Nano-hydroxyapatite/chitosan-chondroitin sulfate composites materials with different weight ratios were prepared through liquid co-precipitation method. The nano-Hap、Hap/Cs and Hap/Cs-Chs composites materials under the same conditions preparation materials were researched By XRD, SEM and EDS respectively. The results show that nano-Hap particles with poorly crystallinity, the size is about 20nm, nano-Hap particles are spherical in sHape and dispersed uniformly, combined with relatively loose between particles, the small nano-particles aggregate into larger particles when the Hap composite with the Cs and Chs, nano-Hap were dispersed uniformly in the organic phase Cs and Chs, Hap particles have the trend to grow large in composites materials,crystal become more perfect, combination become relatively dense between particles, The composites materials were annealed at 700°C,Hap crystal particles become more perfect clear and larger with relatively loose between particles.EDS analysis showed that the compound before and after annealing of the material ratio of calcium had no influence, material does not contain any impurities,The ratio of calcium and phosphorus is about 1.75:1,Hap belonging to the type of calcium-rich

Abstract: The laser surface alloying for metallic materials has been applied widely to improve the wear resistance, corrosion resistance and other required properties. The studies of laser surface alloying on copper-base materials are becoming more and more important. This work using two methods of pretreated coatings, i.e., chemical bonded 50%Cr-50%Cu and pure Cr powders and electroplating chromium coating respectively, on pure copper substrate surface to prepare laser alloyed Cu-Cr alloy coatings was investigated. The samples were treated with different laser scanning speed. Using scanning electron microscopy (SEM), micro-hardness indentor and wear tester, the effects of different coating processing parameters on the microstructure and properties of Cu-Cr coatings were determined and analyzed respectively.

Abstract: Copper oxide and pure chromium being as raw materials,CuCr contact composites can be fabricated through the self-propagating high-temperature synthsis technology,then the microstructure of the samples was observed under a metallographic microscope and the effects of different chromium content on hardness and electric conductivity of CuCr alloys were studied.The experiment's results showed that the SHS reaction of CuO-Cr-Al system could react drastcally,give off a lot of heat and CuCr alloy could be obtained simply as well as with low cost. With the increase of the chromium content, the hardness of the CuCr alloy was elevated, but the electric conductivity was decreased.

Abstract: Anodic oxidation in situ preparation of titanium matrix TiO2 nanotube and optimize the preparation process parameters. With the help of X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) technology we characterized the light catalyst that we have prepared. By oxidation degrading methylene blue, we tested its light catalytic activity. The result showed that the TiO2 nanotube maded at 20 V anodizing voltage, ionic liquids (2 ml), ammonium fluoride (0.684 g), ethylene glycol volume (200 ml) and water volume (6 ml)after 20 h, after dried for 30 min under 105 oC and annealed for 1 h under 500 oC in air became anatase phase, and the ratio of rutile phase is very low. The TiO2 nanotube arrays we made under the above condition for the degradation of methylene blue are good. The average diameter of a nanotube is about 90 nm, and the average thickness of a nanotube’s rampart is about 10 nm.

Abstract: A new Cu-15 Ni-10 Mn alloy was researched and analyzed by optical microscope and metallographic measuring software in three geometry directions of ingots. The distribution of elements of alloy was scanned by EDS of EDΛX. The change rule and cause in various geometric directions in microstructure were analyzed. The results show that the structure of ingot of Cu-15 Ni-10 Mn alloy is in a typical crystal segregation state, the main branches (i.e. first dendrites) size of crystal gradually enhances from the edge to the center of ingots. The average space of secondary arms (branches) becomes larger along the casting direction of ingots. The content of Ni and Mn elements is higher, but the content of Cu is lower in the braches than space of branches

Abstract: Annealing and Al gettering were performed on upgraded metallurgical grade multicrystalline silicon (UMG multi-Si) wafers with a purity of 99.999%. The dislocation and grain boundaries of samples were characterized by optical microscopy and electron back scattering diffraction (EBSD), respectively. The minority carrier lifetime and resistivity of the Si wafers were measured using microwave photoconductance decay and four-point probe techniques, respectively. The results show that the number of dislocations in Si wafers reduced obviously after annealing and Al gettering for 2 hours at 600～1100°C. The proportion of Σ3 grain boundary increases. But the minority carrier lifetime and resistivity of the Si wafers after annealing decreases. However, the minority carrier lifetime and resistivity of the Si wafers after Al gettering increases firstly and then decreases with increasing of the annealing temperature. It is considered that the metal impurities determine electrical properties of UMG multi-Si wafers rather than dislocations and grain boundary. However, Al gettering can enhances the properties of Si wafers effectively and the optimal effect of Al gettering has been achieved at 800°C.