Advanced Materials Research Vols. 233-235

Abstract: A convincing interpretation to hexagonal prism ordered-arrangement and self-ordering cell in porous anodic alumina (PAA) is absent up to now. Based on the growth model of oxygen bubble mould effect (OBME) for PAA, a satisfactory explanation for the growth process of hexagonal cells is proposed. The columnar pores and hexagonal cells result from the oxide growth embracing oxygen bubbles. The avalanche electron multiplication at critical thickness dc leads to electronic current which gives rise to the evolution of oxygen gas under anion-contaminated alumina (ACA) layer. The holes on the surface are usually irregular whereas the pores under the surface layer (ACA layer) are big and regular. The thickness of the barrier oxide layer remains constant due to continuous releasing of the oxygen bubbles at the critical thickness. The self-ordering of cell arrangement and the ordered morphology are related to the dissolving process of the ACA layer on PAA surface.

Abstract: In the present investigation, the composite powder with 20wt.% particulate B4C and 80wt.% nanocrystalline 5083 Al was fabricated using mechanically milling at cryogenic temperature (cryomilling). After this, the cryomilled composite powder was homogeneously blended with an equal amount of unmilled coarse-grained 5083 Al. The blended powder was consolidated with hot-pressing at 500°C, followed by hot extrusion at 410°C. The consolidated composite consists of 10wt.% B4C, 50wt.% coarse grain 5083 Al and the balance nanocrystalline 5083 Al. The microstructure evolution of the composite during cryomilling and consolidation was investigated by X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM). The results show that the particle size of the cryomilled composite powder became smaller and then bigger with milling time longer. This demonstrates the course rely mainly on broken first, and then rely mainly on cold welding with milling time longer. B4C particles can be distributed in 5083 Al matrix uniformly. In addition, the presence of oxygen and nitrogen in cryomilled powders has been demonstrated in this paper.

Abstract: The PMMA/TiO₂ nanocomposites were prepared by in situ polymerization，the dissolution, thermal stability and the mechanical property of the nanocomposites were studied. The results indicated that nano-TiO₂ may be crosslinking points in the matrix and the thermal stability of the nanocomposites became higher. As the content of nano-TiO₂ increased, the mechanical properties of the nanocomposites had great changes.

Abstract: Polyhedral oligomeric silsesquioxane (POSS) can be incorporated into polymers to obtain organic/inorganic hybrid materials. Octaepoxysilsesquioxane (E-POSS) with eight reactive epoxy groups per molecule is an important kind of POSS. E-POSS was cured with 4,4'-diaminodiphenylsulfone diamine (DDS) in this study. The curing kinetics of the E-POSS/DDS system was studied by using differential scanning calorimetry (DSC). Kinssinger and Flynn-Wall-Ozawa methods were used to obtain the activation energy and pre-exponential factor of the curing reaction.

Abstract: The paper puts forward a structural fuzzy optimal means based on member reliability analysis and compares this means with common fuzzy optimum means on a example. The results indicates that the structural fuzzy optimal means based on member reliability analysis gives attention to fuzziness and reliability and structural optimization and makes the structure achieve the unification on economy and security.

Abstract: A series of phosphors with the composition of Y_2.95-xCa_xAl_5-xSi_xO₁₂: Ce³⁺_0.05 (x=0, 0.15, 0.30, 0.45, 0.60, 0.75) were synthesized with conventional solid state reactions. The results of XRD patterns show that in a certain extent, the co-substitution of Ca²⁺ and Si⁴⁺ does not change the garnet structure of samples, while results in the shrink of crystal lattice(The cell parameter of phosphors decreases with the increment of co-substitution content monotonically. The former is in linear with the latter). The measurement of the excitation and emission spectra shows that the co-substitution of Ca²⁺ and Si⁴⁺ make the emission peak move to short wavelength. The amount of blue shift is also in linear with the co-substitution content.

Abstract: Glass in Na₂O-CaO-SiO₂ was synthesized by conventional molten cooling method and then converted to glass-ceramics. Transparent glass-ceramics obtained by controlled crystallization process. DSC, SEM and XRD were used to determine the character temperature, microstructure and crystal type of the glass-ceramics, respectively. The results show the transition temperature of the matrix glass is 620°C and crystallization peak temperature is 730°C. Only Na₂Ca₂Si₃O₉ crystal phase was found in the glass-ceramics when the matrix glass was treated at 750°C for 1h. The crystal with size of 0.5um arranged regularly and formed a honeycomb-like structure in the glass-ceramics. UV-visible spectrum test indicate the transmittance of the glass-ceramic is as high as 75% in the visible region.

Abstract: On the basis of the proposed analytical phase transformation model, a new modified numerical model is presented to evaluate grain density evolution with only basic kinetics parameters. The proposed model is applicable for phase transformation including random nucleation, growth and impingement under isothermal condition. A two-step fit of the current model to numerical calculation describes the grain density evolution and the transformation kinetics well. Compared with the KJMA model, the modified method is advantageous for application without considering complex and detail transformation process.

Abstract: This study attempts to make use wii remote and infrared light emitter as an interactive interface for children on their activities. Using flash software to design teaching materials with the assistance of interactive device could also be developed in the children’s body activities and knowledge. When detected by a wii remote and infrared (IR emitter) device, corresponding information appears on a screen to increase the interaction of assistive technology aimed at children by adopting an enhanced learning process. This study is divided into training and testing steps. The training step allows researchers to learn how to created relative teaching materials for children with learning body coordination. The participants are children in elementary school and kindergarten in the testing step. In this study, the devices relied upon friendly design, reducing the loading from their learning process and enhance their learning motivation.

Abstract: ZnO:Al (AZO) films were prepared by radio frequency (RF) magnetron sputtering at various RF power (70-200W), the electrical and optical properties of AZO films were first investigated. The films deposited at 170W and 200W had the optimum opto-electrical property and then were surface textured by a post-deposition chemical etching with 0.5% HCl for 10-30s, all these films developed a craterlike surface morphology and the crater became larger and deeper as the etching time was increased. The light scattering property of AZO films was researched by calculated spectral haze. The AZO film deposited at 170W and etched 30s had the optimal light scattering property due to its most suitable craterlike surface morphology. Introduction