Applied Mechanics and Materials Vols. 490-491

Abstract: Polyaniline/Nickel hydroxide composites were successfully obtained on the Au substrate pretreated by 4-ATP. They were characterized by fourier transform infrared (FT-IR) spectroscopy and scan electron microscopy (SEM). The capacitance performance of PANI/Ni (OH)₂ composites were studied by cyclic voltammetry and galvanostatic charge/discharge. The specific capacitance of Polyaniline/Nickel hydroxide composite is up to 310 F/g at the current density of 1 mA/cm² in 1.0 mol/L Na₂SO₄ solution. Electrode mass increases from 0.14 mg to 0.21 mg, specific capacitance decreases 7.7%. A symmetric capacitor was assembled by using PANI/Ni (OH)₂ as both of the positive and negative electrodes and 1 M Na₂SO₄ as the electrolyte. It displays a energy density of 6.0 Wh kg^-1 at the power density of 3125 W kg^-1, which is much higher than symmetric capacitor assembled by PANI-PANI (4.9 Wh kg^-1) and Ni (OH)₂-Ni (OH)₂ (3.5 Wh kg^-1).

Abstract: A preparation of nanometer silver sol by micro arc discharge has been study here through the reduction of Ag₃PO₄. Sodium citrate and polyvinylpyrrolidone were added respectively into the electrolyte as stabilizer. The results show that, the Ag₃PO₄ concentration, stabilizer type and concentration have great impacts on the formation of the nanometer silver sol. By means of UV-VIS extinction spectrophotometer, scanning electron microscope and energy dispersive spectrometer, it is found that the solid powder extracted from the electrolyte solution after discharge is the aggregation of the silver formed in the solution and their original size maybe less than 20nm. Nanometer silver with smaller size and narrower size distribution can be obtained with sodium citrate as stabilizer than with polyvinylpyrrolidone. But the latter has higher conversion rate. From this experiment, we found that micro arc discharge can be a rapid, stable preparation method of nanometer silver sol.

Abstract: The autoclave moulding process of composites is characterized by reentrance, capacity and time constraints. Its scheduling directly affects productivity and production cycle of composites. Scheduling methods in the existing literature can't meet the requirements of its scheduling optimization. Aiming at improving utilization and reducing energy consumption of autoclave, based on the Theory of Constraints, a heuristic algorithm considering the capacity and time constraints is proposed to solve the scheduling problem, and priority scheduling rules are established. The studying of a case shows the effectiveness of the algorithm.

Abstract: Now days the application of nanomaterials was vastly growing in the development of new material to improve the quality of human life. Particles of nanomaterials which are in nanoscale helps to improve to the characteristics of the existing micro based materials. The application of nanomaterials in the construction were started since in the early 90s when during those time micro based materials was very demanding especially when dealing with High Performance Concrete (HPC). The utilization of nanobased materials improves and reinforces the cement matrix system and performs early strength and also enhances tensile properties of concrete. In this research, two types of clay were used which nanometakaolin and nanometaclay. nanometakaolin were made from sol gel process thats involved milling technique and nanometaclay were supplied by Sigma Aldrich. The mix proportion for clay based cement paste also includes metakaolin as cement replacement material. nanometakaolin and nanometaclay was added as additives from 0, 1, 3, 5, 7, 9 percent (%) from weight of cement and will be compared to OPC as control specimen. nanometakaolin and nanometaclay inclusion in cement paste will be evaluated for morphology effect by using Scanning Electron Microscope (SEM), chemical composition by using X-Ray Fluorescent (XRF) technique and strength properties. From morphology evaluation, the shape of the particles and particularisation of the matrix observed on the nanometakaolin, nanometaclay and plain cement paste were compared. Similarly, the strength of the plain cement paste shows was compared with those of nanometakaolin and nanometaclay. From the results, shows that inclusion of nanometakaolin at 7% additives generates early strength of cement paste and at 28 days of age addition of 1% of nanometakaolin was found to be the optimum addition level. The addition of 1% nanometakaolin acts as an ultra-filler and refines the microstructure of concrete. Furthermore, nanometakaolin also produces a secondary hydration product by optimizing the remaining calcium hydroxide which was not fully removed during the hydration period.

Abstract: Hot-stamping technology applies hot-stamping dies to the forming and quenching of austenitized high-strength steel plates to produce super-high-strength parts. To carry out these forming and quenching functions, the hot-stamping dies must be able to withstand shock and high-temperature friction under harsh working conditions, and hence high-quality die materials are necessary. However, since the material performance requirements of hot-stamping dies have not been standardized, and special die materials have not been developed, the choice of materials is based on improving the safety coefficient, which leads to material waste and increased costs. In this article, the performance of the hot-stamping process is analyzed to obtain the main resistance indices and a material selection formula for hot-stamping dies, enabling the selection of hot-stamping die materials to be quantified, and thereby establishing a scientific basis for the selection process.

Abstract: TiCp/Al composites coating was in-situ synthesized on the L1060 alloy surface by TIG cladding. The microstructure and the phase of the coating were analyzed by OM, SEM, ADS and XRD, and the properties was been tested by micro-hardnessmeter and wear testing machine. The results show that the composite coating has no porosity, inclusions and other defects. The microstructure of the composite coating mainly consists of TiC particle and aluminum. Microstructural evidence suggests that the formation of TiC occur not only by reaction between Ti dissolved in Al and Al₄C₃, but also by reaction between C dissolved in Al and Al₃Ti. The hardness of the composite coating obtained by TIG cladding is up to 120HV_0.2. The wear resistance of composite coating is 1.6 times more than that of the matrix.

Abstract: In this article should be noted that the accuracy of determining the viscosity of the flow is particularly low in the highly elastic with state of the polymer. It is therefore very important to identity the viscosity of the flow, which has great practical significance. solidity can be changed as a result of intermolecular interaction which can be observed in the process of polymer swelling, which means improving its chain flexibility and lowering the temperature of vitrifying. It should be noted that the processing of the experiment showed no pronounced dependence of the voltage, so it is under-read as the average results for all levers of the stress at a fixed temperature. Processed a method for determining the viscosity of polymer materials, which allows you to divide segmental strength and toughness of the true flow.

Abstract: Ni-30wt%Fe elemental power mixture was mechanically milled under argon atmosphere for variuos times up to 25h.The evolution of Ni-Fe alloying during milling and the microstructure of the as-milled powders were characterized by XRD, EPMA (electron probe microanalysis), SEM and TEM, respectively. The results show that nanocrystalline Ni (Fe) supersaturated solid solution alloy powders with 30wt. % Fe in composition can be synthesized by mechanical milling of the elemental powder mixture. Both the content of Fe dissolved and the microstrain developed in the as-synthesized Ni (Fe) solid solution phase increase, while the crystallite size decreases, steadily with increasing milling time. In particular, the Ni-30wt%Fe alloy powders obtained by 25h milling consist of a single Ni (Fe) supersaturated solid solution phase with average crystallite size of about 15nm and accumulated microstrain as high as 1.12%. DSC tests show that the nanocrystalline Ni-30wt%Fe alloy powders have a lower melting temperature than the elemental powder mixture, attributed to the unique Ni (Fe) solid solution phase structure, the nanocrystallization, and the high strain energy.

Abstract: The effects of doping with VC (grain growth inhibitors) on the microstructural characteristics and mechanical properties of WC-Al₂O₃ compacts prepared by hot-pressing sintering were investigated. VC suppressed the rate of densification during isothermal sintering, but eventually increased the sintered density with extended holding time. Microstructure observation results revealed that the grain growth of WC was significantly retarded with the addition of VC. Meanwhile, the activation energy for grain growth during isothermal sintering increased from 380.75 to 446.68 kJ/mol, which is consistent with the inhibition mechanism of VC.