Eco-Materials Processing and Design IX

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Authors: Jong Tae Jung, Jong Oh Kim, Bum Gun Kwon, Dong Ha Song
Abstract: This study was conducted to evaluate the treatment performance of the system using peroxy radical/ozone reaction for refractory organic compounds removal in aqueous solution. The effect of initial humic acid concentration was conducted under the conditions of humic acid concentration 10 mg/L, 30 mg/L, 50 mg/L and 100 mg/L. Reaction rate constant (k) in 30 mg/L of humic acid concentration was higher than that of humic acid concentration 10 mg/L, 50 mg/L amd 100 mg/L. However, it decreased over the range of 30 mg/L of humic acid concentration due to the action of internal filter of humic acid itself. Reaction rate constant (k) in the initial 20 minute of reaction time was accelerated by decreasing hydraulic retention time (HRT). This may be ascribed to increase the reaction time between peroxy radical and ozone. pH is a key for both ozone stability and TiO2 surface property in aqueous solution. Reaction rate constant (k) of acid solution on pH variation was smaller compared to that of neutral or basic circumstances because ozone decomposes easily into hydroxyl radicals in neutral or basic solution. At reaction rate constant (k) for humic acid degradation in each unit process, peroxy radical/ozone combined system was higher than that of ozone only due to the effective production of hydroxyl radical. An obvious difference between ozone and peroxy radical/ozone is the consequence of hydroxyl radical produced by the reaction of ozone molecules and peroxy radicals.
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Authors: Joon Jae Lee, Jeong Kwon Suh, Ji Sook Hong, Jung Min Lee, Jin Won Park
Abstract: In this study, spherical activated carbons contained ZnS(Zn-SPAC) were successfully prepared through carbonization/activation processes. Strong acid ion exchange resin as starting material of Zn-SPAC was treated by 0.01 N zinc solution. Ion exchange treatment was performed from one time to three times for controling zinc content. The ion exchanged resins was activated under N2/H2O-vapor atmosphere at 900 °C for 0.5 hr following by carbonization treatment at 700 °C under N2 atmosphere. The Zn-SPAC samples were measured physicochemical characteristics such as X-ray patterns, SEM image, energy dispersive X-ray spectra, BET specific surface area, intensity and zinc content and used to remove humic acid(HA) in batch reactor for measuring photochemical activity. The X-ray patterns were appeared ZnS type. The Zn-SPAC had large BET specific surface area and their shape was spherical with a diameter about 350 ~ 400 μm. When the Zn-SPAC were dosed in UV reactor, the HA removal efficiency increased upto 60 % at 4hr. The order hand, the HA removal efficiency by only UV-C(λmax =254nm) irradiation was not good about 15 %. Therefore, we infer that the Zn-SPAC have good photochemical activity and presented possibility of photocatalyst for water purification.
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Authors: Jae Kyung Yoon, Sang Hyun Bae, Jin Wook Ha, Hyun Ku Joo
Abstract: In this study, an anodized TiO2 electrode (ATE) on a titanium foil was prepared and used as a photoanode in an enzymatic photoelectrochemical system to split water into oxygen and hydrogen. The effect of applied voltage when anodized, thickness of foil, electrolytes, annealing temperature, and species of cathode was investigated. The optimum conditions were obtained such as 0.25 mm foil thickness, 20V of applied voltage in 0.5 vol% of hydrofluoric acid, and 650 oC of annealing temperature. The samples with higher activities had similar X-ray diffraction (XRD) patterns, clearly indicating that the samples showing the highest evolution rate were composed of both anatase and rutile, while those showing a lower evolution rate were made of either anatase or rutile. Increasing the intensity of the irradiated light caused a remarkable enhancement in the rate of hydrogen production up to 153 μmol/(hr×cm2) under light intensity of 146 mW/cm2.
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Authors: Hai Yun Jin, Guan Jun Qiao, Zong Ren Peng, Ji Qiang Gao
Abstract: SiC particles coated with nano-BN were synthesized and the machinable SiC/BN ceramic nano-composites were fabricated by Plasma Active Sintering (PAS) in N2 atmosphere. The existing and distribution of h-BN phase were revealed by X-ray diffraction (XRD), and SEM. For the existing of weak interface between h-BN and SiC grains, the machinability of both SiC/BN micro-composites and nano-composites were improved obviously. Because the nano-sized h-BN crystals were homogeneously dispersed around the SiC grains of the matrix, the fracture strength of the nano-composites was better than the SiC/h-BN micro-composite.
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Authors: Juan Li Yu, Hong Jie Wang, Hong Zeng, Dan Bo Lin, Zhi Hao Jin
Abstract: Porous Si3N4 ceramics by gel casting preparation has received considerable attention because of its excellent performance. In the paper, orthogonal experimental design L16(45) was used to investigate the preparation of porous Si3N4 ceramics by gel casting preparation. Three variables including solid loading, monomer content and the ratio of crosslinking agent to monomer were studied. Through range analysis and variance analysis, the results suggest that the ratio of crosslinking agent to monomer has significant influences on both the flexural strength and porosity of Si3N4 sintering body. For the flexural strength of Si3N4 sintering body, the order of significance levels was as follows: the ratio of crosslinking agent to monomer, solid loading and monomer content. For the porosity of Si3N4 sintering body, the order of significance levels was as follows: the ratio of crosslinking agent to monomer , monomer content and solid loading.
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Authors: Tao Jiang, Hai Yun Jin, Zhi Hao Jin, Jian Feng Yang, Guan Jun Qiao
Abstract: The machinable B4C/BN ceramics composites were fabricated by hot-pressing sintering process at 1850oC for 1h under the pressure of 30MPa. The mechanical property, thermal shock behavior and machinability of the B4C/BN ceramics composites were investigated in this article. The experimental results showed that the fracture strength and fracture toughness of the B4C/BN nanocomposites were significantly improved in comparison with the B4C/BN microcomposites. The Vickers hardness of the B4C/BN nanocomposites and B4C/BN microcomposites decreased gradually with the increasing content of h-BN, while the machinability of the B4C/BN nanocomposites and B4C/BN microcomposites were significantly improved. The B4C/BN ceramics composites with the h-BN content more than 20wt% exhibited excellent machinability. The thermal shock resistances of the B4C/BN ceramics composites were better than that of the B4C monolith, and the thermal shock resistance of the B4C/BN nanocomposites was much better than that of the B4C/BN microcomposites. The thermal shock temperature difference (-Tc) of B4C monolith was about 300oC, while the -Tc of the B4C/BN microcomposites was about 500oC, the -Tc of the B4C/BN nanocomposites was about 600oC.
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Authors: Hwa Shin Lee, Dong Bok Lee
Abstract: The high-temperature oxidation resistance of the WC-CrN superhard nanocomposite films was studied at 600 and 700oC in air. The oxidation of the film resulted in the formation of volatile species such as the evolution of carbon probably as CO or CO2, evolution of nitrogen from the film, and the formation of W-oxides. The scale formed was prone to cracking and spallation.
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Authors: Dae Yong Shin, Kyung Nam Kim
Abstract: MgO thin film was deposited on soda lime glass substrate by sol-gel process. MgO thin film with the (200) preferred orientation were prepared by heat-treated at 300~500°C for 10 min. The crystallization, microstructure and electrical properties with various parameters of MgO thin films were investigated. Consequently, it was shows that the (200) preferred orientation of MgO thin film could be obtained as the heating temperature was increased. At heating temperature of 500°C, MgO thin film was composed of columnar crystals with a size of 120 nm. The dielectric constant of the (200) preferred orientation of MgO thin film at 1 kHz without the electric field was 7.2, with a dissipation factor of 4%. When the electric field was increased, the dielectric constant approaches to 7.9 with the dissipation factor of 2.1%. The refractive index of MgO thin film depended on the film thickness. The refractive index of 250 nm thickness was 1.70.
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Authors: Seung Joon Ahn, Ho Seob Kim, Dae Wook Kim, Seong Joon Ahn
Abstract: The electron beam lithography has been paid great attention as a future lithography technology for the patterning of extremely fine structures. Generally the e-beam lithography means high-energy e-beam lithography where the kinetic energies of electrons are rather high(10~100 keV). Although the high-energy e-beam technology is mature and being used in semiconductor industry, the low-energy microcolumn lithography(LEML) has many great advantages as a next-generation technology, which explains the active research on the subject these days. In this work, we developed a new method to recognize the registration marks in LEML. With this novel method, there is no need to supply the bias to the mark electrodes, which remarkably simplifies the fabrication process of IC devices.
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Authors: Moon Kyong Na, Hoy Yul Park, Dong Pil Kang, Myeong Sang Ahn
Abstract: Three kinds of colloidal silica (CS)/silane sol were prepared. Sols are involved with the kinds of silane with different organic group. Methyltrimethoxysilane (MTMS) has the three methoxy groups and a methyl group. γ-Glycidoxypropyltrimethoxysilane (GTMS) has the three methoxy groups and a bulky epoxy group. GTMS was added to two sols with different amount. When sol reacted for 10 days, viscosity increased dramatically. Trasnmittance of sols reacted for 10 days decreased rapidly, too. It indicated the stability of sol degraded. Sol-gel coating films were formed on glass substrate using spin coating procedure with reaction time for 10 days. Coating films were flat and transparent without cracking. CS/MTMS coating films showed high contact angle. When large amount of GTMS was added, contact angle decreased due to its epoxy group. No thermal degradation of CS/MTMS coating film occurred up to 600 oC. CS/MTMS/GTMS coating film degraded at 400 oC for decomposition of epoxy group which has long organic chain which easily degraded by the thermal shock.
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