Advanced Materials Research Vols. 430-432

Abstract: Electrical discharge dressing and truing of diamond grinding wheel is a non-contact and non-traditional truing and dressing technology. In orde to help selecting optimized parameters under certain conditions such as peak current,etc.Fractal theory is application to set a electrical dischrge model .In this model,the fractal dimension ( ) is proportionately related to peak current( ) and pulse duration ( ).The actual dressing experiment was conducted to demonstrate the simulation model. There is a relationship between fractal dimension ( ) and the surface morphology of diamond grinding wheel.

Abstract: The microstructure evolution and precipitation behavior of two low carbon steels are studied, with 0.05C-0.77%Nb added in one steel and (0.03C-)1.63Cu-0.74%Nb added in the other as a comparison. In the Cu-Nb steel tempered at 600°C for 18 hrs, there are two peaks in the particle size distribution figure, one between 2-3nm formed by NbCN precipitates, and the other, 10-12nm for Cu precipitates. The TEM observation on carbon replica shows that the average particle diameter of NbCN precipitate is 2.81±0.78nm in C-Nb steel, while 4.23±0.95 nm in Cu-Nb steel with lower carbon. The analysis shows that this size increase of NbCN not only decreases the precipitation strengthening, but also weakens significantly the pinning effect on the dislocations, which results in a more serious microstructure softening in Cu-Nb steel.

Abstract: Superplastic forming provides significant industrial application for forming complicated, lightweight components of aerospace propulsion application. Since superplastic forming process is a function of temperature, time, applied pressure and contact condition of the matched surfaces, the oxidation is one of the concerned subjects. In the present work, the oxidation behavior of UNS31803 was studied in superplastic forming atmosphere. It is shown that the Pieraggi model is successfully applied to the high temperature oxidation of this alloy. The effective activation energy of the oxidation is 399 KJ/mol at this condition.

Abstract: In this paper, ceramic coatings were produced on LY12 aluminum alloy by the micro-arc oxidation (MAO) technique in an alkali sodium silicate electrolyte consisting of different KF concentrations(0~15g/l). The influence of KF concentration on making energy consumption and thickness of the MAO coatings was studied. Results revealed that increasing KF concentration caused an increase in the thickness and roughness of coatings and a decrease in the average energy during the MAO process. In response to the increase in KF concentration, the little content of F- in the coatings were increased simultaneously. However, the phase structure and composition of the coatings hardly varied with different KF concentrations. Moreover, it was observed that the coatings produced in electrolytic solution with 10g/L concentration of KF obtained an excellent thickness and making energy, but the coatings were ablated locally with the KF concentration of higher than 10g/L for more than 60 minutes.

Abstract: Based on the theories, , and we can improve , the heat transfer resistance of retaining structure, or reduce ,the heat transfer coefficient, through the heat insulation design of outer wall, roof, ground, the door, and outer window and the thermal bridge, and finally realize the building energy conservation goals. Residential energy consumption is a important factor of China's energy saving. Exterior wall, roof, ground, the door, the external window and thermal bridge is the key parts of energy consumption of residential building.

Abstract: The particle swarm optimization was applied to the optimum design of the composite box structure.The total weight of the structure was taken as the objective function.A technique of applying PSO integrated with general finite element code was developed for the optimization.Optimization was also conducted using zero-order method included in ANSYS and a comparison was made between zero-order method and PSO.Results demonstrate that PSO can find the global optimal design with higher efficiency regardless of the initial designs.for zero-order method the optimum solution is worst than the result of the PSO optimum.

Abstract: The grafted copolymerization of dimethyldiallylammoniumchloride (DMDAAC) and N,N'-methylene bisacrylamide onto cassava starch was investigated with water as solvent and ammonium persulfate-sodium sulfite as redox initiator. In above conditions, double crosslinking amphoteric cassava starch was synthetized by using sodium hydroxide as catalyst, epichlorohydrin as crosslinking agent and chloroacetic acid as etherification agent. The DS and DC could reach to 0.108 and 0.391 respectively under the following conditions: m(AGU) : m(DMDAAC)=1:1.5, the initiator mass fraction 3.5% (vs. dry starch), grafted polymerization temperature 45°C and time for 5 h, etherification temperature 50°C and time for 5 h, n(AUG):n(ClCH₂COOH)=1:1 and n(AUG):n(NaOH)=1:1.5. The product was characterized by infrared spectrum (FTIR), scanning electron microscopy (SEM) and X-ray diffraction spectrum (XRD). The results indicate that the cassava starch is modified successfully, and the final product is a novel double crosslinking amphoteric cassava starch.

Abstract: A series of ZnO:Al (AZO) thin films was prepared on quartz at different substrate temperature using magnetron sputtering with high deposited rate of 67 nm/min. The structural, electrical and optical properties of these films were investigated as a function of substrate deposition temperature ranging from room temperature to 500 °C. The surface micrograph of AZO film deposited at room temperature was measured by a scanning electron microscope (SEM) and an atomic force microscope (AFM). The results of X-ray diffraction (XRD) test show that all the films have a (002) preferential orientation. The best electrical property was obtained at 500 °C, the resistivity was 9.044×10-4 ohm•cm, and the corresponding carrier concentration and mobility were 3.379×1020 /cm3 and 20.45 m2/Ns, respectively. What's more, all the films show a high optical transmittance.

Abstract: The residual compressive strength of a foam core sandwich panel after low-velocity impact was studied by using experimental and analytical methods. The test specimens were compressed uniaxially after they were subjected to a low-velocity-impact. From the observation in the test, one can conclude that the subsequent core crushing around the impact region is the major failure mode in the sandwich structure. A failure criterion named Damage Propagation Criterion was proposed to predict the residual compressive load bearing capability of the low-velocity impacted composite sandwich panel. The characteristic value used in this failure criterion can be calculated by an analytical model developed or by conducting the Sandwich Compression after Impact test.

Abstract: Graphene oxide (GO), an oxygen-rich carbonaceous layered material, is produced by the strong oxidation of graphite. The GO aqueous suspension is very stable and can be fabricated to porous GO aerogels by a green method, unidirectional freeze-drying technology. GO shows catalytic activities in both solution and solid state. It can also act as reductant or oxidant depending on the reaction patterns. The product of the reaction was analyzed and the component change of the graphene oxide (GO) was monitored by x-ray photoelectron spectrometer, scanning electron microscopy and transmission electron microscopy. The results confirm that GO not only acts as the reactant in the reaction, but also as the catalyst to catalyze the reaction.