Advanced Materials Research Vols. 239-242

Abstract: An advanced ceramic material of perovskite structure, Sc₂O₃ (5 mol%) and Gd₂O₃ (5 mol%) co-doped SrZrO₃, was investigated as a material for thermal barrier coating (TBC) applications. Sr(Zr_0.9Sc_0.05Gd_0.05)O_2.95 (SZSG) was synthesized using ball milling prior to solid-state sintering, and had a minor second phase of Gd₂O₃. The material showed good phase stability not only from room temperature to 1400°C, but also at high temperature of 1450°C for a long period, analyzed by DSC and XRD, respectively. The thermal expansion coefficients (TECs) of the sintered bulk SZSG were recorded by a high-temperature dilatometer and revealed a positive influence on phase transitions of SrZrO₃ by co-doping Sc₂O₃ and Gd₂O₃. The thermal conductivity of SZSG had much lower values in contrast to that of SrZrO₃ and Sr(Zr_0.8Gd_0.2)O_2.9 in whole tested temperature range. The good chemical compatibility was observed for SZSG with 8YSZ or Al₂O₃ powders. All the results revealed that SZSG might be a potential material for TBC applications at higher temperatures compared with 8YSZ.

Abstract: Nitroreductase (NR) was modified on glass carbon electrode and used in nitrobenzene analysis. Both cyclic voltammetry (CV) and triple potential step chronocoulometry (TPSC) with a narrow potential step interval were used. The modification of nitroreductase improved the sensitivity and selectivity of nitrobenzene detection. Both the peak area and peak current were examined for quantitative analysis, showing a linear relation between nitrobenzene concentration and peak area, and a logarithmic relation for peak current, with correlation coefficients of 0.9981 and 0.9993, respectively. Statistical tests to evaluate the reliability of TPSC showed that there was no evidence of systematic error, and it was not significantly different from CV or high performance liquid chromatography (HPLC). The new method could avoid most interferents, showing good selectivity.

Abstract: A modified fractal growth model of minerals was considered in the square lattice 300 × 300. One seed is placed at the center of the square lattice as a growth focus and the attraction domain is set to diamond. Three main parameters are considered in this model which probability of the surface adhesion is Pg with the range of 0 to 99% to eliminate the noise impact and adsorption distance d varies from 0 to 9 units on behalf of the gravitational field strength between particles and fill gaps s varied from 0.00 to 5.00 units distance to perform the influence of environmental temperature on the minerals growth system. Three model sets are carried out with two fixed parameters and the other changed parameter. The results show the fractal dimension of DLA group increase with the decrease of Pg and the increases of d and s, as well as the structure of minerals from disseminated, star or radial gradual transition to agglomerate. The model is a two-dimensional simulation for three-dimensional fractal growth and can not fully reflect the complex growth dynamics of mineral aggregate in three-dimensional confined space.

Abstract: A model for grain growth simulation, in the presence of the second phase particles, is established with the help of a Cellular Automata method. The effect of the time when the second phase particles are introduced on grain growth is simulated. The simulation results show that the second phase particles inhibit the grain growth and the earlier the particles are introduced, the better the pinning effect.

Abstract: The corrosion process was analyzed for carbon steel when used in Ca(ClO)₂ hypochlorite Disinfection Solution. The corrosion resistance of Ni-P electroless coating was characterized by electrochemistry method. From the results, it was shown that the corrosion reaction can occur spontaneously according to the caculation result. The corrosion products existing on the carbon steel surface were loose and porous. The main conpositions of the products are about iron oxide. For Ni-P coatings, the corrosion current densities reduced gradually with the increasing of electroless plating time.

Abstract: Lyocell, commercially supplied by Lenzing Fibers under the trade name Tencel are used in the manufacture of dry-laid and wet-laid nonwovens as well as speciality papers for high performance. The fibrillation behaviour of Tencel fiber on different SEL condition was studied in this paper. The results show that Tencel fiber can be well fibrilated with long fiber length after refining at 0.4-0.8Ws/m SEL. The distribution of microfibers diameter are mostly between 200nm to 2000nm. The fibrilated fibers were applied in alkaline Zn/MnO₂ battery separator. The properties of the resulting papers in comparison to the commercial separator are much better especially in prorosity and pore size.

Abstract: The dispersive characteristic of anti-plane elastic waves propagating through laminated piezoelectric phononic crystal is studied in this paper. First, the transfer matrix method (TMM) and the Bloch theorem are used to derive the dispersion equation. Next, the dispersion equation is solved numerically and the dispersive curves are shown in Brillouin zone. The pass band and the stop band of anti-plane SH wave propagating perpendicular to and oblique to the laminated periodic structure are compared. The effects of the slope angle on the wave band structure are discussed.

Abstract: This paper has built the engine mathematical model of surface fitting using MATLAB language based on the evaluation index experimental method of vehicle fuel economy. The paper proposed a new calculated and rendering engine Universal Characteristics Curves by using the fitting tools and statistical software package of MATLAB language. According to the fuel consumption rate curve graphical method, the paper has established the calculation process and the method of constant speed fuel consumption. The method has been proved that is intuitive and practicable.

Abstract: The microstructure of fatigue fracture of aluminum alloys under various stresses and stress ratios were studied by optical microscope and scanning electron microscope, and the influences of microstructure features on microcrack initiation and propagation were investigated. The results show that the fatigue microcrack originated from surface or subsurface of specimens. And with the increase of stress ratio, fatigue crack originated from deeper subsurface at the same stress level. With the increase of stress level, fatigue crack originated from shallower subsurface or surface at same stress ratio. There is an increase in crack propagation region as the stress level decreases at the same stress ratio. Increasing of stress ratio, increases crack propagation region under same stress level. Microcrack generally originated from secondary (S phase particles) and larger particles at low stress level and high stress ratio. Microcrack generally originated from larger constituent particles at high stress level and low stress ratio. Microcracks propagation is evidently impeded by grain boundaries at low stress level and high stress ratio.

Abstract: Multiferroic ceramic samples of Bi_1-xGd_xFeO₃ (x = 0, 0.05, 0.1 and 0.15) have been prepared by the rapid liquid phase sintering technique. The effect of Gd substitution on ferroelectric properties of Bi_1-xGd_xFeO₃ ceramics has been investigated. The results of x-ray diffraction (XRD) patterns show that the single-phase BiFeO₃ sample has a rhombohedral structure and Gd³⁺ substitution for Bi³⁺ has not affected the perovskite structure. Experimental results suggest that Gd³⁺ substitution for Bi³⁺ has markedly affected the Raman scattering spectra, and the ferroelectric properties of BiFeO₃ are improved by Gd³⁺ doping. When x = 0.15, saturated ferroelectric hysteresis loop is observed at room temperature with the maximal 2Pr = 1.62 μC/cm².