Materials Science Forum Vol. 694

Abstract: Relaxation and local structure changes of a molten Cu135 cluster have been studied by molecular dynamics simulation using embedded atom method when the cluster is rapidly quenched to 700K, 600K, 500K, 400K, 300K, 200K, and 100K. With decreasing quenching temperature, details of energy evolvement and relaxation are analyzed. The simulation results show that the final structures are molten at 700K, like-icosahedral geometry at 600K-200K, non-crystal at 100K. The average energy of atoms is the lowest at 500K, and in the relaxation has abrupt increase at 25,135 and 42ps separately at 400K, 300K, and 200K. The simulation reveals that the quenching temperature has great affect on the relaxation processes of the Cu135 cluster after β relaxation region.

Abstract: The n-SiO2/FeS solid lubrication composite coating is prepared by means of the comprehensive treatment process of gridded laser quenching, low temperature ion sulfuration and vacuum impregnation technology. The tribological properties of n-SiO2/FeS solid lubrication composite coating are investigated under the condition of dry sliding, and the lubrication mechanisms are also preliminary discussed. The experiment results reveal that the friction coefficient of the coating is in the range of 0.065~0.10 when tested in 4067 minutes. Furthermore, its wear rate is only 6% of FeS solid lubrication duplex coating. This is testified that the n-SiO2/FeS solid lubrication composite coating is durable with low friction coefficient and wear resistance.

Abstract: The carbide rotary burs with the shape of a cone upside down are kind of very special cutting tools. They have a very important application in model machining. And the function could not be substituted by any kind of other cutter. This paper uses a hyperboloid of one sheet to imitate the cone, uses the straight rural line as the cutting edge, and presents a simple method to machining this kind of cutter with helical cutting edges. Only the tradition machine tool is needed for the generation of this kind of complicated cutting tools.

Abstract: Based on micropolar fluid theory and micropolar solid elasticity theory, reflection and transmission characteristics of three kinds of micropolar elastic waves, which are longitudinal displacement wave and two coupled waves, were studied when incident longitudinal displacement wave propagated in micropolar fluid with micropolar elastic plate. Using numerical example, the variations of various amplitudes are also shown against the angle of incidence and the variation characteristics of various amplitudes are discussed. Results show that there exist maximum values of reflection and transmission coefficient for coupled wave, however, there exist minimum values of reflection coefficient for longitudinal displacement wave, and transmission coefficient decreases with the incident angle and the transmission coefficient are smaller for bigger incident angle.

Abstract: We have calculated the energy band structure of spin-polarized electronic in Zn15Y1O16 and Zn14Y1O16 and the formation energy of Zn10Y4O16 in the ferromagnetical and antiferromagnetical state by the linear augmented plane wave based on the local density approximation. The results show that the Y doped ZnO film may be ferromagnetic and Zn vacancy (VZn) is the origin of ZnO thin film with Y doping.

Abstract: Micrometer-sized mesoporous silica SBA-15 spheres with good dispersivity were successfully synthesized by adding the soluble starch into the aqueous solution containing P123 and tetraethyl orthosilicate, based on the special function of water-soluble polymer in the sol-gel process. The obtained SBA-15 silica spheres were characterized by scanning electron microscopy, X-ray diffraction and N2 physisorption technique. The obtained SBA-15 spheres possessed pore size from 17.4 nm to 24.3 nm and the specific surface area from 565.3 m2 g-1 to 459.4 m2 g-1. Furthermore, the dispersibility of SBA-15 silica spheres was good. The results showed that appropriate amount of soluble starch improved the uniformity and dispersibility of silica spheres, while the structure and pore size of the obtained SBA-15 silica spheres with hexagonal symmetry created by P123 remained unchanged.

Abstract: In this study, we developed an efficient catalysis-oxidation method for the degradation of phenol in wastewater, in which the Fe3O4 nanocrystals and H2O2 were employed as catalyst and oxidation agents respectively. Firstly, Fe3O4 nanocrystal coated with PEG was prepared via an oxygenation-deposition hydrothermal method, TEM, FT-IR, BET and XRD characterization indicated that the prepared Fe3O4 nanocrystals had an average size of 26 nm and the specific surface of 35.25 m2/g. Using the prepared Fe3O4 nanocrystals as catalyst, the phenol in wastewater was efficiently degraded by H2O2. The degradability of the phenol was investigated by FT-IR, HPLC and UV–visible spectrophotometer, and the experimental results showed that the phenol was efficiently degraded by H2O2 and the Fe3O4 nanocrystals could be efficiently recycled. Finally, the possible catalytic reaction mechanisms and pathways of phenol degradation were discussed.

Abstract: Under the terrible environment in the aero-engine, the blade, made of Ti-5Al-2Sn-2Zr-4Mo-4Cr titanium alloy, is prone to result in fatigue failure. So improving the titanium alloy performance is becoming very significant. In this paper, the microstructure and microhardness of Ti-5Al-2Sn-2Zr-4Mo-4Cr titanium alloy with and without laser shock peening (LSP) were examined and compared by XRD, TEM and microhardness test. The XRD tests pointed out that LSP generated the microstrains and grains refinement in the material surface. The TEM results indicated that great high density dislocations were generated and evolved into the dislocation wall, small-angle boundary and large-angle boundary. The nanocrystallites were formed and became more and more uniform after 4GW/cm2. The grains nanocrystallization in the surface layer helps to improve the material performance. The microhardness test result showed that LSP could increase the hardness by 20 percent or so. And the affected depth is about 700μm.