Eco-Materials Processing & Design VII

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Authors: Eun Yi Kim, Yoo Hang Kim, Chin Myung Whang
Authors: Jong Hyuck Han, Soo Wohn Lee, Eun Ah Lee, Tian Ying Xiong, Zebin Bao, Hao Du
Abstract: Cold spray process offers an oxidation-free atmosphere. It is usually used for TiO2 coatings used in photocatalytic applications to purify a given medium. Cold sprayed coatings with spray dried powder and evaporated powder were compared. Investigation of properties using SEM, XRD, roughness test were performed. SEM and XRD data were found to be very similar, however, variations were found for the surface roughness. Nano-sized powders were used in this investigation, therefore the coatings achieved were very thin in comparison to those from conventional powders, also they showed high uniformity.benzene removal from air by means of photoelectrocatalytic reaction was achived.
Authors: Hyun Ku Joo, Sang Bong Lee, Yong Gun Shul, Jin Wook Ha
Abstract: This study investigated the effects of constituents in bio/photocatalytic hydrogen production system using an experimental design tool, a fractional factorial design. The factors considered included species of buffer solution, the amount of hydrogenase (Pyrococcus furiosus, Pfu), electron donor, reaction temperature and electron mediator. The experiments were designed to determine critical conditions that were required to achieve the highest level of H2 production.
Authors: Shan Zheng, Lian Gao
Abstract: Titanium oxynitride and molybdenum oxynitride assembled in the pores of mesoporous materials were achieved by nitriding titania-modified MCM-41 and molybdena-modified MCM-41 at 800°C for 3 hours under flowing NH3 atmosphere. XRD, XPS and N2 adsorption-desorption isotherms were employed to characterize the structure of the composite materials. The results showed that the nanosized TiOxNy and MoOxNy particles were assembled in mesoporous silica MCM-41 with the restrict mesopores. The hexagonal periodicity of the parent MCM-41 materials was maintained upon assembly at the provided nitridation temperature. The exact formation was TiO0.4N0.8 in MCM-TiOxNy, and MoO1.7N0.57 in MCM-MoOxNy, which were calculated from the data in XPS spectra of Ti 2p and Mo 3d.
Authors: H.S. Jeong, J.R. Cho, Nak Kyu Lee, H.C. Park
Abstract: The manufacturing process of the exhaust valve in large marine diesel engines consists of an upset forging and final forming process. In the past, the exhaust valves in large marine diesel engines have been made through free forging by using the stretch forming method. This method has used the ingot and the billet as a preliminary forming process. Nimonic 80A, a superalloy, is presently used for the material of the exhaust valve. For the forming method of the valve, the electric upset method is used. Solid bar is raised up to the forming temperature by using electric energy and is continually deformed by upset pressure. The electric upsetting processing is a useful method for the high quality of exhaust valves in large marine diesel engines. It can keep the continuous grain flow, excellent mechanical property, and corrosion resistance because of the elaborate macrostructure of the valve face. The purpose of this paper is to predict the optimum process condition through simulation of the exhaust valve with a diameter of 73mm. The experimental result of an exhaust valve with a diameter of 19mm is in good agreement with the simulation result using the “QForm” that can solve electric upsetting problems. Finally, the optimal manufacturing process of the electric current and the upset load are surveyed.
Authors: Ju Hyun Myung, Hyoun Woo Kim, S.H. Shim
Abstract: We report on the first synthesis of nanosized In2O3 rods using the TEI as a precursor in the presence of oxygen. The samples were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy. XRD analysis revealed that the products are In2O3 phase with a tetragonal cubic structure. SEM analysis indicated that the obtained nanorods have a circular cross section and a diameter in the range of 50-150 nm.
Authors: Yasuo Yamada, Takumi Banno, Zhen Kai Xie, Cui E Wen
Abstract: The mechanical properties of a closed-cell aluminium foam were investigated by compressive tests, and the deformation behaviours of the aluminium foams were studied using Xray microtomography. The results indicate that the deformation of the aluminium foams under compressive loading was localized in narrow continuous deformation bands having widths of order of a cell diameter. The cells in the deformation bands collapsed by a mixed deformation mechanism, which includes mainly bending and minor buckling and yielding. Different fractions of the three deformation modes led to variations in the peak stress and energy absorption for different foam samples with the same density. It was also found that the cell morphology affects the deformation mechanism significantly, whilst the cell size shows little influence.
Authors: Chong Mu Lee, Seung Mo Kang, Keun Bin Yim, Sook Joo Kim, Hyoun Woo Kim
Abstract: Epoxy molding compounds (EMC) with higher thermal stabilities are urgently needed as the light emitting diode (LED) becomes brighter and the wavelength of the its light becomes shorter. This paper proposes a simple reliable method of evaluating the thermal stabilities of commercial EMCs. The transmittances of most commercial EMC samples for high power short wavelength LED packages were decreased by heat treatment at 150oC for 200hr. Also the thermal stabilities of the samples were confirmed by measuring the weight losses through TGA. The experimental results suggest that employing a good heatsink is indispensable in highly bright short wavelength LED packages.
Authors: Seong Jong Kim
Abstract: FRP (fiber-reinforced polymer) ships used with small boats for fishing pose numerous problems related to both the environment and recycling. From this perspective, aluminum offers an environmentally friendly substitute for FRP that is easy to recycle and imparts a high added value to fishing boats, with a reduction in fuel demands. The current density of 7075 Al alloy increases linearly with an increase in potential during anodic polarization, which implies that no passivation of this alloy occurs. With 1050 and 5456 alloys, passive films form during anodic polarization but are destroyed by the Cl in seawater, only to regrow as a result of the self-healing capacity of aluminum. A shift to more anodic or cathodic conditions in the potential range of –1.5 ~ –0.68 V resulted in a sudden increase in current density. Current densities in the high-strength 7075 Al alloy showed the greatest values. In contrast, the current densities of 5456 alloy, known to have excellent corrosion resistance in seawater, were the lowest in the range of –0.70 ~ –1.3 V, and we conclude that this potential range offers optimal protection.

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