Advanced Materials Research Vol. 853

Abstract: In this paper six sides top technology of high temperature and high pressure, in AlN nanopowder mixed with Mo powder, synthesis of AlN - Mo. Nanocomposite ceramics Using X-ray diffraction (XRD), scanning electron microscope (SEM) and vickers hardness instrument of AlN - Mo in the nanocomposite ceramics phase structure, morphology, size and hardness of the characterization, compared with AlN nanoceramic, discusses the AlN - Mo of nanocomposite ceramics new features.

Abstract: Characteristics of silica optical material largely depend on its thermal history. In this paper, formation of thermally induced defects in silica optical material is studied. The formation process of defect is analyzed in detail. The results show that there is an obvious difference in defect formation induced by heating treatment when the composition of silica optical material changes. Defect formation mainly displays as the produce process when the initial defects of the silica material are zero. However, defect formation expresses as the produce and annealing process when the initial defects of the silica material are not zero. The initial defect concentration can be decreased significantly when the silica material is heated in high temperature. At the same time, the new defect is also produced. These theoretic results are consistent with the previous experimental ones.

Abstract: Improving high-temperature strength of aluminum piston material is a core technology for diesel engines to high speed and high intensity. To figure out the influence of alumina reinforced aluminum composites to the thermal load of high intensity piston, this paper study the properties of the alumina fiber reinforced aluminum composite and its protection for piston. The research shows that, compared with the cast aluminum, the high tensile strength and fatigue limit of the composite were increased by about 25% and 26% respectively. Therefore, the alumina fiber reinforced composite could not improve the temperature distribution of the piston, but it can improve high temperature strength and the operational reliability of the piston.

Abstract: Diatomite supported Cu-doped TiO₂ photocatalysts were synthesized by sol-gel method and characterized by X-ray diffraction (XRD), SEM and UV-vis diffuses reflectance of spectroscopy (DRS). The photocatalytic activity was evaluated by photocatalytic degradation of methylene blue solution under visible light irradiation. The results show that TiO₂/diatomite ratio had a great influene on their photocatalytic activities. All prepared Cu-TiO₂/diatomite had a better photocatalytic activities in comparison with Cu-TiO₂ and the Cu-TiO₂(30)/diatomite had higher photocatalytic activity than others. The photocatalytic degradation of methylene blue is due to the breaking of the chormophoric group, rather than the simple decoloration.

Abstract: Soft conductive elastomer materials have wide potential applications in material science and electronic engineering. Through electrospinning and in-situ polymerization, a kind of well-organized coaxial polyaniline/polyvinylidence fluoride (PANI/PVDF) microfibers with conductivity about 0.6 S/cm were fabricated, which combined the advantages of conducting polymer and elastic material. It is found that the resistance of the fibers was changed with the curvature variation. The results indicate that the PANI/PVDF microfibers could be used as strain sensor with high flexibility, high sensitivity, and stable repeatability.

Abstract: Lithium secondary batteries using LiNi_0.5Mn_1.5O₄ (LNMO) films as a cathode material were prepared by pulsed laser deposition on stainless steel substrates. X-ray diffraction and Field-emission Scanning Electron Microscope results show that the film deposited at 750°C exhibits good crystallinity with well-defined grains structure. Galvanostatic charge/discharge measurement results revealed that the reversible capacity maintains 116.8mAhg^-1 after 100 cycles at 0.5C. It also exhibits excellent rate capability, as the rates increase to 5 and 10 C, about 95.4% and 92.3% of its initial capacity at 0.2C can be retained. In additional, thermal stability of the Al₂O₃ coated LNMO thin film cathodes were also explored. The high temperature cyclic performance of LNMO thin film electrode was significantly enhanced by the coating.

Abstract: In order to improve the poor wettability of SiC_p/Al composites, surface modification by copper brush plating and an active Al-base solder containing Cu, Mg and Sn were investigated in this paper. After vacuum brazing, a good soldered joint with high shearing strength of 145.6MPa was succesfully frabricated at 580°C, holding time of 30min. The microstructure of soldered joints was studied by SEM and EDS. The results show that the Cu-plating , as a bridge, could obviously enhance the reaction between the molten solder and composites, the fractography revealed the fracture occurs within the composite, indicating a good adhesion between the solder alloy and the SiC_p/Al composites.

Abstract: By an oxidation-reduction reaction the polyester film would be coated with a layer of tin. The conductivity of polyester film was discussed under different plating time, temperature, and PH. The results showed that when the plating time was 60 minutes, the temperature was 90°C and the PH was 4, the polyester film attained the optimal conductivity. The polyester film could be protected and the combination of magnetic and electrical conduction would be achieved by coating with a layer of magnetic powder after plating.

Abstract: By employing the electrospinning technique and subsequent carbonization processes, porous carbon/nickle (C/Ni) composite nanofibers with diameters of 100-200 nm were successfully prepared. Two polymer solutions of polyacrylonitrile (PAN), polyvinyl pyrrolidone (PVP), and Ni (CH₃COOH)₂ (Ni (OAc)₂) were used as C/Ni composite nanofiber precursors. The study revealed that C/Ni composite nanofibers were successfully prepared and nickle particles with diameters of 20-70 nm were uniformly scattered in the carbon nanofibers. It was also observed that the fiber with clear fibrous morphology with particles broke into shorter fibers after sinter. X-ray diffraction (XRD) showed that these particles crystallized with the face centered cubic (FCC) structure. The Brunauer-Emmett-Teller (BET) analysis indicated that C/Ni composites nanofibers with meso-pores possessed larger specific surface area than that of carbon nanofibers.

Abstract: Nanoparticles in solution offer unique electrical, mechanical and thermal properties due to their physical presence and interaction with the state of dispersion. This work aimed to study the effects of hydroxyapatite (HA) nanoparticles on the behavior of devitrification and recrystallization of glycerol (60% w/w) and PEG-600 (50% w/w) solutions during warming. HA nanoparticles of different sizes (20nm40nm60nm) and contents (0.1%0.5%,w/w) were incorporated into solutions, and were observed under a cryomicroscope. Experimental results showed that the morphologies of glycerol and PEG-600 solutions are dendritic and spheric respectively. The ice fraction of glycerol solution containing 0.1% HA with the size of 60nm decreased to 2/5 of that of solution without nanoparticles. The ice fractions of PEG-600 solutions with and without nanoparticles increased significantly between-64 °C and-54 °C, and the ice fraction of PEG-600 solution without nanoparticles increased by 92% within the temperature range. The findings have significant implications for biomaterial cryopreservation, food manufacturing, and cryosurgery.