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Authors: Takeshi Ohgai, Masayuki Mizumoto, Shigeki Nomura, Akio Kagawa
Abstract: A polycarbonate membrane filter with numerous cylindrical nanopores was used as a template for growing metallic nanowires such as Ni, Co and Fe. The nanoporous template with pore-diameter of 150 nm, pore-length of 6000 nm, and pore-density of 108 pore•cm-2 was modified as a cathode with sputter-deposited gold layer. Inside the nano-pores, the metallic nanowires were electrochemically deposited from an acidic sulfate solution containing metal ions. The growth rate of metallic nanowires depended on the cathode potential during electrodeposition. The diameter of electrodeposited nanowires corresponded to that of nanopores in the template. TEM diffraction pattern suggested that each metallic nanowire composed of a single crystalline structure.
Authors: Myoung Ryul Ok, Eun Young Kang, Ji Hye Kim, Young Su Ji, Chang Woo Lee, Young Joo Oh, Kyung Tae Hong
Abstract: Plasma electrolytic oxidation (PEO) has drawn attention and been studied intensively all through the world. The thick ceramic coatings fabricated by the technique exhibit excellent properties, including hardness and wear resistance, thermal and electrical insulation, and corrosion resistance, due to the characteristic phase composition and microstructure of the coating layers. However, most of the studies have dealt with manufacturing process itself and the apparent properties of coating layers and researches on the microstructural basis including transmission electron microscopy analysis are limited so far. In this investigation, a basic approach to PEO process was tried, adapting time-potential behavior analysis under constant current mode (galvanostatic) oxidation, and microstructural analysis on the coating structure, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The time-potential behavior analysis under constant current DC was carried out, and the resultant evolution of the microstructure was characterized..
Authors: S.Y. Park, Moon Chul Kim, Chan Gyung Park
Abstract: Nano structured WC-Co coatings with carbide size of 100−200nm were fabricated by detonation gun spraying. The fabricated nano coatings showed improved hardness and wear resistance compared to micron WC-Co coatings. Considerable phase decomposition of WC to W2C and amorphous phase in nano coatings was detected, which is known to degrade wear resistance of coatings. In order to improve the wear resistance of the coatings by recovering of dissociated carbide phases, post heat treatment was conducted in Ar environment at temperature range of 400−900°C. Harness, fracture toughness and wear resistance of nano coatings were significantly improved by post heat treatment. The improved properties were elucidated and discussed in terms of microstructure and phase compositions.
Authors: J.J. Park, Han Cheol Choe, Yeong Mu Ko
Authors: Evy De Bruycker, Zinedine Zermout, Bruno C. De Cooman
Abstract: Demands for highly corrosion resistant coated steel are growing. As a result, Zn-Al-Mg coatings were developed. The possibilities of these coatings were investigated and the thermodynamics of the Zn-rich corner of the Zn-Al-Mg system were modelled. Different Zn-Al-Mgcoatings were produced and the microstructure was studied. Simulations of the solidification microstructures were carried out. The properties of the different coatings, like corrosion resistance and formability, were investigated. The thermodynamic model fairly accurately predicted the liquidus and transformation temperatures for low amounts of Al (≤4wt%) and Mg (≤3wt%). In the coatings the MgZn2 phase was present instead of the thermodynamically stable Mg2Zn11. The coatings with 3wt%Mg consisted of primary Al-fcc, MgZn2 crystals and ternary Zn-hcp/Alfcc/ MgZn2 eutectic. The addition of small amounts of Mg to a galvanizing bath caused a Znhcp/ MgZn2 eutectic to grow at the grain boundaries. Mg additions to a Zn+5wt%Al bath resulted in coarsening of the Zn-hcp/Al-fcc eutectic when added in small amounts and, when added in larger amounts (>0.2wt%Mg), a ternary Zn-hcp/Al-fcc/MgZn2 eutectic appeared. Cyclic corrosion tests and bending tests showed that the addition of Mg greatly enhanced the corrosion resistance, but decreased the cracking resistance of the coatings.
Authors: M.J. Franklin, S.W. Huang, Tara Chandra, A. Kiet Tieu
Abstract: This research is part of a larger project to investigate the wear and friction of the centre bearing of a rail freight truck. Existing centre bearing surfaces include flame hardened AISI 1030 steel and AISI 1053 cast steel top centres mating against un-greased and/or greased Hadfield steel centre bowl liners, and polyethylene centre bowl liners. The wear life of the unlubricated steels against Hadfield steel is short, greasing the bearings is costly, and industry reports some failures of polyethylene centre bowl liners due to excessive plastic flow and cracking of the rim wall.
Authors: Ko Shao Chen, Su Chen Chen, Yi Chun Yeh, Hong Ru Lin, Wen Fu Lee, Heng Hsien Lee
Abstract: This study was compare of physics and chemical property of Styrene-butadiene-styrene (SBS)/ Acrylic acid (AA) copolymer after thermal polymerization and UV graft-polymerization. The result of this study shows: when the thermal polymerization was used, the grafting percentage of SBS-g-AA rose along with the increase of the AA monomer concentration. The maximum occurred when SBS=0.5g and AA=2.5 x 0.0065mol, then it decreased along with the increase of the AA concentration. The transition ratio and grafting percentage decreased as the concentration of SBS increased; while AA was fixed on 0.0065mol, the maximum grafting percentage occurred by using 1g SBS. The grafting percentage increase along with the increase of reacting time, and it reached the maximum after reacting 3 hours. The water contact angle was lowered from 82o to 58o. Using the UV graft-polymerization, when AA monomer concentration increased, the grafting percentage increased as well; the maximum occurred when AA concentration was 2.88M. Moreover, the grafting percentage was increasing along with the increase of reacting time, but it stopped increasing around 40 minutes reacting time. The grafting percentage of thermal polymerization was higher than UV graft-polymerization. It shows that the swelling ratio of membranes grafted using the UV light was higher than those grafted by thermal polymerization.
Authors: You Wang, D.L. Wang, G. Liu, W. Tian, C.H. Wang
Abstract: In this paper, Al2O3/TiO2 coatings via thermal spray approach using three different feedstock powders, i.e., (a) reconstituted nanosized Al2O3/TiO2 feedstock powders, (b) reconstituted nanosized Al2O3/TiO2/ZrO2/CeO2 feedstock powders and (c) conventional Al2O3/TiO2 feedstock powders are described. Effects of different powder types and various plasma spray conditions on the density, microhardness and crack resistance, especially on the abrasive wear behavior of the coatings have been evaluated. The result showed that the coatings sprayed using different feedstock powders exhibit different abrasive wear behavior with changing the plasma spray conditions. The coatings sprayed using the reconstituted nanosized Al2O3/TiO2/ZrO2/CeO2 feedstock powders showed a significantly improved wear resistance compared to the coatings sprayed using reconstituted nanosized Al2O3/TiO2 feedstock powders or conventional Al2O3/TiO2 feedstock powders. The wear mechanisms of the coatings were discussed.
Authors: Ludwig Jörissen, Werner Lehnert, Juergen Garche, W. Tillmetz
Abstract: In this paper reactions having strong influence on the lifetime of PEMFCs are described. These lifetime limiting reactions are related to the catalyst (increase of the particle size, catalyst dissolution, oxidation of the carbon catalyst support, catalyst deactivation by contaminants), to the membrane (degradation, loss of membrane humidification, increase of membrane resistance), and corrosion of structural components (e.g. metallic bipolar plates). Examples for such reactions are shown and rate determinining parameter are discussed.
Authors: Søren Linderoth, Peter Halvor Larsen, M. Mogensen, Peter V. Hendriksen, N. Christiansen, H. Holm-Larsen
Abstract: The SOFC technology under development at Risø National Laboratory (RISØ) and Topsoe Fuel Cell A/S (TOFC) is based on an integrated approach ranging from basic materials research on single component level over development of cell and stack manufacturing technology to system studies and modelling. The effort also comprises an extensive cell and stack testing program. Systems design, development and test is pursued by TOFC in collaboration with various partners. The standard cells are thin and robust with dimensions of 12 x 12 cm2 and cell stacks are based on internal manifolding. Production of cells is being up-scaled continuously. The durability of the standard stack design with standard cells has been tested for more than 13000 hours including nine full thermal cycles with an overall voltage degradation rate of about 1% per 1000 hours. Recently, the degradation rate has been significantly reduced by introduction of improved stack component materials. 75-cell stacks in the 1+ kW power range have been tested successfully. Stacks have been delivered in a pre-reduced state to partners and tested successfully in test systems with natural gas as fuel. The consortium of TOFC and RISØ has an extended program to develop the SOFC technology all the way to a marketable product. Stack and system modelling including cost optimisation analysis is used to develop multi kW stack modules for operation in the temperature range 700-850oC. To ensure the emergence of cost-competitive solutions, a special effort is focused on larger anode-supported cells as well as a new generation of SOFCs based on porous metal supports and new electrode and electrolyte materials. The SOFC program comprises development of next generation of cells and multi stack modules for operation at lower temperature with increased durability and mechanical robustness in order to ensure long-term competitiveness.

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