Applied Mechanics and Materials Vols. 341-342

Abstract: The photoluminescent properties of Na, Bi co-doped CaWO₄:Eu³⁺ phosphor under vacuum ultraviolet (VUV) region excited was investigated. A red emission of CaWO₄:Eu³⁺ can be observed under 147 nm excitation. It was also found that the photoluminescence intensity of Na doped CaWO₄:Eu³⁺ would be enhanced than the un-doped phosphors due to Na⁺ ions would act as a charge compensator and it can restrict the generation of defects in CaWO₄:Eu³⁺. Additionally, the photoluminescence enhancement of Na⁺, Bi³⁺ co-doped CaWO₄:Eu³⁺ should due to the energy transfer between WO₄^2-, Bi³⁺ and Eu³⁺, and Bi³⁺ ions would act as a medium for the energy transfer, via WO₄^2-Bi³⁺Eu³⁺. These are expected to be applying in plasma display panels.

Abstract: An green method to reduce graphene oxide (RGO) was developed by using polysaccharide as both a reducing agent and a stabilizing agent. The RGO was characterized and the factors that affect the reduction of graphene oxide (GO) were explored to obtain optimum reaction conditions. Analysis shows that GO can be reduced at a comparatively low temperature by polysaccharide and forms a stable RGO aqueous dispersion owing to the dispersion of polysaccharide. This approach provides a new green method for GO reduction that has great value for graphene applications.

Abstract: Pure and Al-doped ZnO thin films were deposited by radio frequency magnetron sputtering at room temperature on n-(100) Si, fused quartz and Pt/Ti/SiO₂/Si substrates. Structural, optical and electrical properties of the prepared thin films had been characterized. The X-ray diffraction results indicated that all the films had (002) preferential orientation. The AFM and SEM images showed that the surface of the films was smooth, crack-free and pore-free, the interface between the film and the substrate was sharp and distinct. From the transmission data the band gap energy Eg of the film increased when doped with Al₂O₃, and the transparent was still high (above 80%). The current voltage characteristics indicated that doping with Al₂O₃, the leakage current of ZnO thin films increased rapidly and the films acted as a conductive.

Abstract: Through ten years physical investigation on the geometrically frustrated coordination compound series basic (hydroxyl and deuteroxyl) transition-metal halides M₂(OH/D)₃X (M=Mn, Fe, Co, Ni and Cu; X=Cl, Br and I), we have determined the existence of four crystal structures, whose space groups belong to Nos. 11, 14, 62 and 166, respectively, in this series till now. After studying their Raman spectra, we firmly believe that a nonnegligible hydrogen bond (H-bond) exists in every material. Considering carefully their local lattice environments of the basic groups, we find a new kind, to the best of our knowledge, of H-bond [(OH)₃···M] and nominate it as the trimeric H-bond, and further confirm three types of symmetric structures, which have totally four subtypes of trimeric H-bonds so far. More two subtypes are predicted to exist in nature. This result may provide a new interesting subject for quantum chemists and material physicists.

Abstract: Laser peening offers potential advantages over conventional peen technologies in terms of the depth of the residual stresses that can be induced, and improvements in surface micro-hardness. The present study was undertaken to understand the effect of laser penning on the properties of titanium alloy, a TC4 titanium alloy work-piece was processed with ND: YAG laser with the wavelength of 1064 nm, pulse energy of 0-10J and pulse width of 12ns, and micro-hardness and residual stress for different laser peening parameters were examined and analyzed by micro-hardness tester and X-ray diffraction. Results are presented and discussed of the residual stress profiles and the micro-hardness profiles, The experimental results show that the satisfying laser peening appearance can be achieved when the pulse energy was 6J, water tamping layer thickness was 1.8mm and ablative layer thickness was 100μm, surface micro-hardness increased by up to 33% and the compressive residual stress on the surface of laser shocked area reached up to-327.8MPa, laser peening improved hardness and residual stress of titanium alloy significantly. The experiment results show that the effect of laser peening was evidently.

Abstract: SHS technique and conventional melting and casting technology were combined and used for the preparation of Al-Ti-C grain refiner alloy. Experimental results show that when SHS reaction occurs to the Al, Ti and C powder reactant in Al melt and the composition proportion factor, n , is between 4 and 10, the effect of composition on the initial temperature of SHS reaction is small and its initial temperature ranges from 810 to 815°C. However, the highest temperature of the melt increases with increasing n values and increases gradually from 845 to 1370°C. In the meantime, when the composition proportion factor for Al, Ti and C powder reactant, n, is greater than 5.95, its adiabatic temperature Td>1800K which conforms to the empirical criterion proposed by Merzhanov et al. The SHS reaction of reactant can accomplish by self-maintenance.

Abstract: Tributyltin (TBT) in water was photocatalytically decomposed in the presence of TiO₂ film photo-catalyst, which was prepared by coating TiO₂ on the industry pure titanium foil. The photocatalytic decomposition rate of TBT is up to 93.8% within 30 min. Photocatalytic decomposition of TBT was greatly enhanced with rate constant nearly 3 times as that by photolysis. TBT decomposed in a stepwise manner, and the main products were monobutyltin (MBT), which is further decomposed to inorganic tin in the system.

Abstract: A poly-Si-Fe (SOPSF) coagulant which have good oxidizing capacity and long storage time was prepared by copolymerization. The oxidation-reduction potential (ORP) value and storing time of SOPSF were explored in comparison with those of poly-Si-Fe (PSF). The results showed that SOPSF and PSF had stronger oxidizing function than Polyferric aluminum (PFA), and SOPSF had better storing stability than that of PSF at different temperatures and different concentrations.

Abstract: The oxidation behavior of a stable-oxidative-poly-Si-Fe (SOPSF) coagulant prepared by water glass and H₂SO₄ solution in treating a synthetic humic acid (HA) water was probed, in compraison with that of poly-Si-Fe (PSF) and Polyferric aluminum (PFA). The results revealed that the oxidization of SOPSF and PSF was very stable during the whole coagulation process, and played a role during the whole process including quiescent settling stage. While PFA almost gave no oxidization even at higher dose of 0.322 mmol.L^-1. The oxidization rate of SOPSF was slower than that of SOPSF hydrolysis and destabilization process. Coagulation mechanism of SOPSF in removing dissolved organic matters (DOMs) may be a comprehensive results between the alternating interaction of oxidization/adsorption-destabilization/oxidization, bridging and sweeping.

Abstract: Introducing the chinese current situation of fly-ash and its main composition and properties, review high-effective extraction methods of Si, Al and Fe from fly ash, and sum up preparation methods, conditions and water treatment results of the polysilicate flocculants with the extracts. At last, provide s some advices on how to get more extracts efficiently from fly ash and gain flocculants with better remarkable coagulant performance.