Advanced Materials Research Vols. 1061-1062

Abstract: So far, thermal shock theories have not been well verified in refractories. This paper compared hypothesis and failure mechanism of two typical thermal shock theories, analyzed the applications of two typical theories in refractories from working environment, failure process and microstructure differences. And thinks that the critical stress fracture theory is suitable for nearly ideal brittle refractory with ceramic bond and used in thermal shock extremely harsh environment; thermal shock damage theory suites to evaluate multiple loops thermal shock. Analyzed the factors influencing the thermal shock parameters, and discussed Ways to improve the thermal shock resistance of refractories from destructive force and resistive force of refractories. Conclusions are that choosing small swelling expansion rate and high thermal conductivity material, reducing the micro stress concentration and adding flexible phase, these three methods can be used to make refractories with good resistance to thermal shock.

Abstract: The anchoring of CFRP tendon can be performed by wedging, bonding or compressing. The wedge type anchor, used for PS steel tendon, is inappropriate for direct application to the CFRP tendon due to its low lateral stiffness. Since the bond performance of the CFRP tendon depends on the anchor performance, the bond type anchor presents the problem of requiring long steel sleeve in case of low bond performance or high tensile performance. Compared to the bond type anchor, the compressing type anchor offers better applicability but necessitates the development of a sleeve fitted to the dimensions of each CFRP tendon. This study intends to examine the anchoring characteristics of the compressed sleeve for the temporary anchorage of a CFRP tendon with diameter of 10 mm. To that goal, the properties of the 10 mm-diameter CFRP tendon were assessed using the bond type anchor and the corresponding anchor performance is compared to that of the compressed anchor. The test results revealed that the use of spacers in the compressed anchor provided lower anchor performance due to the characteristics of the spacers. For the specimen without spacer, the micro-deformations formed inside the sleeve were seen to compress the CFRP tendon by gearing directly the tendon and to provide anchor performance reaching about 72% of the tensile strength of the CFRP tendon. Further study shall develop a sleeve with increased compress force on the CFRP tendon so as to improve the anchor performance of the compressed sleeve. Moreover, solution shall also be provided to introduce a uniform compress force.

Abstract: In this study, a polydimethylsiloxane (PDMS) coating filled with low concentrations of selected carboxyl modified multi-walled carbon nanotubes (cMWCNTs) has been fabricated. The antifouling properties of cMWCNTs-filled PDMS coatings were tested and the diversity level and succession phenomenon of marine fouling microbial communities were analyzed using single strand conformation polymorphism (SSCP) method. Marine adhesion test showed that cMWCNTs-filled PDMS coating presented decent antifouling property. SSCP analysis revealed that fouling prokaryotic species on the cMWCNTs-filled PDMS coating presented high and stable diversity level while diversity and dominance level of fouling eukaryotic species were relatively low, similar to those on PDMS alone and other four antifouling coating surface without nanoparticles, suggesting that the main mechanism by which cMWCNTs-mediated surface nanostructure improves antifouling capacity may have no direct relationship with the patterns in the context of succession dynamics of prokaryotic and eukaryotic microbial communities.

Abstract: SAPO-34 molecular sieve was successfully synthesized using calcined-MCM-41 as silica source and morpholine as a template. The influence of MCM-41 content on the synthesis was investigated. The result shows that pure SAPO-34 could be obtained in a wide range of the n (SiO₂)/n (Al₂O₃) ratio in the starting gel. Moreover, increase the n (SiO₂)/n (Al₂O₃) ratio has a negative effect on crystallinity while high silicon incorporates into the framework of SAPO-34. Keywords: MCM-41, SAPO-34, Silicon source,

Abstract: ZnO/SnO₂/montmorillonite that could flocculate and restrict the growth of Microcystis aeruginosa used as a probe of cyanobacterial was prepared and characterized by means of XRD and TEM. In ZnO/SnO₂/montmorillonite, ZnO and SnO₂ nanoparticles disperse on montmorillonite surface. The determinations of chlorophyll a levels and total soluble protein content demonstrate that ZnO/SnO₂/montmorillonite has stronger flocculation effect on Microcystis aeruginosa compared with natural montmorillonit under visible light, and has a good photocatalytic degradation effect on Microcystis aeruginosa under UV irradiation. Under UV, 96.79% removal efficiency is achieved for Microcystis aeruginosa in 1h using 50mg.L^-1 ZnO/SnO₂/montmorillonite. The synergy of absorption flocculation and photocatalysis of ZnO/SnO₂/montmorillonite promotes the removal of Microcystis aeruginosa.

Abstract: The effects of surface treatment of a carbon fiber (CF) by Polyethylene-polyamine (PEPA) on the interfacial adhesion behavior and morphology of polypropylene/polystyrene (PP/PS) matrix blends filled CF composites were investigated. Effects of surface treated a commercial CF on mechanical properties are studied. Contact angle was measured to examine the changes in wettability of the carbon fiber. The chemical and morphological changes were characterized by using X-ray photoelectron spectroscopy (XPS). PP/PS/CF composites were fabricated with and without PEPA treatment, and their interlaminar fracture toughnesses were compared. The results showed that the interlaminar shear strength (ILSS) of composites has been greatly improved filled PEPA modification CF. The water contact angle of resin sample decreased 50% after addition of PEPA surface treated CF.

Abstract: A method to grow gallium nitride (GaN) films directly on the graphene layers by hydride vapor phase epitaxy (HVPE) method is reported in this work. We used a chemical vapor deposition (CVD) method to grow graphene on a copper foil, and the test results showed the presence of monolayer graphene at most regions. GaN films were grown on the graphene/MO-GaN substrate (GaN which was grown by metal organic vapor phase deposition) and MO-GaN template by HVPE method. Raman Spectroscopy, Scanning Electron Microscopy (SEM), and X-Ray Diffraction (XRD) were adopted for characterization. By comparing with the MO-GaN substrate, the crystalline quality of the GaN films were both increased. However, the crystalline quality of the HVPE-GaN with graphene interlayer is slightly lower than that directly grown on MO-GaN.

Abstract: ZnO nanostructures prepared by thermal evaporation method using Zn metal plate in water vapor were invitigated. The Zn metal plates were ultrasinically cleaned at room temperature and then heated in a furnace at temperatures ranging from 350 to 430 °C for 2 hours. The ZnO nanostructures were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD patterns show the ZnO hexagonal wurtzite structure. SEM images indicate that the ZnO structures depend on preparation temperatures. The density of ZnO nanostructures increase as the temperature increases. The transformation of ZnO nanostructures was observed to be temperature dependence. The nanostructures are nanorods when prepared at temperature below 400 °C, nanowires when prepared at 400 °C, and nanoflakes when prepared temperatures of 410 °C or higher. This approach provides the capability of creating patterned 1D ZnO nanowires at 430 °C. The diameter of ZnO nanowires werevaried from 20 nm to 70 nm and length of several 400 micrometers.

Abstract: By using a elastic mechanics model the transverse magnetoelectric voltage coefficient of magnetostrictive-piezoelectric bilayer is derived according to the constitutive equations. The transverse magnetoelectric coupling of nickel zinc ferrite-lead zirconate titanate (Ni_0.8Zn_0.2Fe₂O₄–Pb (Zr,Ti)O₃, NZFO-PZT) layered composites were calculated by using the corresponding material parameters of individual phases. NZFO samples have been synthesized with sol–gel technique. Layered composites NZFO-PZT and NZFO-PZT-NZFO have been fabricated by binding discs of NZFO and commercially available PZT, and the transverse magnetoelectric effect have been investigated. The peak value of transverse magnetoelectric voltage coefficient for NZFO-PZT-NZFO trilayer reaches 252.4 mV/cmOe under a bias magnetic field of about 320 Oe, which is about three times as large as that of NZFO-PZT bilayer. The interface coupling parameter of trilayer is significantly higher than that of bilayer.

Abstract: BiFeO₃ and Eu/Co doped BiFeO₃ thin films have been grown on Nb:SrTiO₃ substrates with pulsed laser deposition using the same growth conditions. It was shown that the characteristic of resistive switching would be enhanced by Co doping. By changing the polarity of the external voltage, the BiFe_0.95Co_0.05O₃ is witched between multilevel stable resistance states without an electroforming process. The resistance ratio is larger than two orders of magnitude and shows stable resistance states. The resistive switching is understood by the electric field-induced carrier trapping and detrapping, which changes the depletion layer thickness at the interface, oxygen vacancy and Co doping play important role in enhanced RS behavior. Keywords: Resistive switching, element doping, resistive switching mechanism.