Enhanced fouling resistance of organosilane-grafted ceramic microfiltration membranes for water treatment

LEE, Jongman,HA, Jang-Hoon,SONG, In-Hyuck,SHIN, Dong Woo Ceramic Society of Japan 2017 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.125 No.12

<P>A facile surface modification technique for imposing antifouling properties on ceramic microfiltration (MF) membranes was developed based on the chemical conjugation of organosilane molecules on ceramics. The ceramic MF membranes (pore size: approximately 0.1 mu m) were fabricated using conventional dip coating in an alumina slurry with nano-sized particles. The membranes were subsequently subjected to organosilane grafting with different molar concentrations (25, 50, and 100 mM). The physicochemical analysis of the organosilane-grafted membranes revealed a small decrease in pore size/roughness, which resulted from the new formation of organosilane multilayers (i.e., pore-filling effect). The pure water permeability was also diminished to some extent while exhibiting minimal influence on the permeation flux. Because of the electrostatic repulsion force between the surface-modified MF membranes and the model foulants, serious foulant adsorption followed by flux decline was significantly alleviated. In particular, the lowest organosilane concentration (25mM) showed the greatest flux performance. This was mostly attributed to the reduced effect of pore-size restriction and electrostatic repulsion forces. We therefore achieved the optimum organosilane-grafting conditions for ceramic MF membranes, which not only minimized the alteration of surface morphology/pore size and hydraulic permeability but also remarkably improved the antifouling properties. (c) 2017 The Ceramic Society of Japan. All rights reserved.</P>

Effect of particle size of tabular talc powders on crystal orientation and sintering of cordierite ceramics

KATAYAMA, Masaki,NAKAKUKI, Jun,PEE, Jae-Hwan,KOBAYASHI, Yuichi Ceramic Society of Japan 2013 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.121 No.1419

<P>Cordierite ceramics were prepared from several types of kaolin powders and talc powders having various median particle size with nanometer-sized alumina sol. Powder mixtures were uniaxially pressed, followed by cold isostatic pressing to make thin compacts. Crystal orientation of talc particle and resultant cordierite were evaluated using the X-ray diffraction profile measured on the uniaxially pressed surface of calcined compacts and sintered compacts, respectively. Coarser talc powders above 3 mu m aligned their c-axis in vertical to the uniaxially pressed surface of the calcined compact during uniaxially pressing, owing to highly anisotropic tabular shape. The crystal orientation of resultant cordierite increased with an increase in the crystal orientation of talc powders on the pressed surface. This result indicated that the c-axis of cordierite crystal preferably oriented vertically to the c-axis of talc particle oriented. Using the combination of kaolin powders below 5 mu m and talc powders having median particle size between 3 and 5 mu m, densely sintered cordierite, having a relative density of 95% and high crystal orientation of approximately 85% [I-110/(I-110+I-002)], could be obtained. (C)2013 The Ceramic Society of Japan. All rights reserved.</P>

Effects of Bi2O3 on the structural, thermal and wetting properties of zinc bismuth phosphate glasses for low-melting sealing glass

KIM, Il-Gu,KIM, Jong-Hwan,JUNG, Jae-Yeop,CHOI, Su-Yeon,PARK, Hyun-Jun,RYU, Bong-Ki Ceramic Society of Japan 2014 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.122 No.1431

<P>The study of lead-free low-melting sealing glass with properties such as low glass transition temperature (T-g), low softening temperature (T-s), good wettability on the substrate, is in process. One of the low-sintering lead-free glass compositions, the bismuth glass system is considered to be an alternative to lead oxide glass. Research on the development of lead-free low-melting sealing glass in ZnO-P2O5-Bi2O3 (ZPB) system was prepared and the effects of substitution of Bi2O3 for ZnO on the structural, thermal, and wetting properties of a sealing glass were studied. The changes in T-g, T-s and coefficient of thermal expansion (CTE) may reflect decreasing connectivity of the glass structure, due to the increasing Bi-O bonds. This structure changes have an effect on wettability on the substrate. The addition of higher amounts of Bi2O3 improved the wettability of the glass on the substrate. The ZPB glass, possessing properties of low T-g and good wettability, is suitable for low-to-mid temperature sealing applications. (c) 2014 The Ceramic Society of Japan. All rights reserved.</P>

Influence of alumina content in the raw clay on the sintering behavior of Karatsu ware

KATSUKI, Hiroaki,KIM, Jaegyeom,KIM, Seung-Joo,KIM, Jong-Young,PEE, Jae-Hwan,CHO, Woo-Seok Ceramic Society of Japan 2016 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.124 No.8

<P>In this paper, mineral and sintering properties of high alumina-containing clay (Yamase clay) derived from a weathered granite stone were investigated, and compared with those of low alumina-containing clay derived from a weathered sandstone (Hobashira clay) for the ancient Karatsu ware. Content of Al2O3 in Yamase clay was 30.8-33.1 mass%, and showed higher than that of Hobashira clay (13.1-15.8 mass%). Yamase and Hobashira clay had a mineral composition of kaolinite (64.3), alpha-quartz (10.6), muscovite (11.9), albite (10.3), and microcline (2.9 mass%), and kaolinite (12.9), alpha-quartz (52.9), muscovite (23.4), albite (6.9), and microcline (3.9 mass%), respectively, by the Rietveld analysis. Bulk densities of Yamase clay heated at 1200, 1300, and 1400 degrees C were 1.99, 2.15, and 2.35 g/cm(3), and Yamase clay had a higher refractoriness than Hobashira clay. After heating Yamase clay at 1300-1400 degrees C, the heated body was composed of fine needle-like mullite (49.8) and glass (50.2 mass%) without the bloating of the body. (C) 2016 The Ceramic Society of Japan. All rights reserved.</P>

Luminescence and structural properties of self-assembled Y(V,P)O4:Eu3+@amorphous-K-VO3 core/shell nanophosphors

SU JO, Deok,SENTHIL, Karuppanan,TAKAKI, Masaki,YOON, Dae Ho Ceramic Society of Japan 2013 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.121 No.1414

<P>A Liquid-Phase Precursor method followed by a 5% KOH solution treatment was employed for the facile synthesis of Y(V,P)O-4:Eu3+@amorphous-K-VO3 core/shell nanophosphors with non-stoichiometric composition Y-x(V0.44P0.56)O-4:Eu-0.1 (x = 0.855, 0.875, 0.90 and 0.965). It was observed that this non-stoichiometric composition approach leads to the control of the size, shape and unit cell parameters depending upon the Y concentration. The shell layer of 2-7 nm formed by alkaline solution treatment at room-temperature was observed by Transmission Electron Microscope (TEM). The particle size grew up by 20-50 nm and the luminescence properties were enhanced by 9-31% after the KOH solution treatment. In contrast, the micro-sized Y(V,P)O-4:Eu3+ phosphors treated by the KOH solution did not show any change in their luminescence properties. This KOH solution treatment opens new possibilities to facilely synthesize Y(V,P)O-4:Eu3+@amorphous-K-VO3 core/shell nanophosphors with highly stable properties and improved luminescence. (C) 2013 The Ceramic Society of Japan. All rights reserved.</P>

Characterization and catalytic behavior of cerium oxide doped into aluminosilicophosphate glasses

PARK, Hyun Joon,RYU, Bong Ki Ceramic Society of Japan 2016 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.124 No.2

<P>Cerium oxide is commonly used as a catalyst for the oxidation of carbon monoxide (CO) in vehicle exhaust gases, and it is used as a petroleum-cracking catalyst in oil refineries. In this study, cerium aluminosilicophosphate glasses were synthesized and various physical and catalytic properties were measured, including optical properties and decomposition temperatures, by thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) analysis. Ce3+/Ce4+ ratios and structural changes in the glass attributable to doping with similar to 25 mol% CeO2 were investigated by FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis. Changes in the catalytic properties of the glasses as a function of CeO2 content were confirmed by changes in the decomposition starting temperatures. These temperatures decreased with increasing CeO2 content of the glasses. We also discuss the role of CeO2 in terms of the catalytic properties of the glass structure. (C) 2016 The Ceramic Society of Japan. All rights reserved.</P>

The effect of sacrificial templates on the pore characteristics of sintered diatomite membranes

HA, Jang-Hoon,OH, Eunji,SONG, In-Hyuck Ceramic Society of Japan 2013 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.121 No.1419

<P>Recently, porous ceramic membranes have become an interesting subject due to their outstanding thermal and chemical stability. Among the many types of ceramics, as diatomite is inherently porous and irregular, it is worthwhile to investigate the relationship between the characteristics of sacrificial templates and porous microstructures after sintering. Therefore, sintered diatomite membranes were prepared with 8 mu m solid polymer spheres, 20 mu m solid polymer spheres, wheat starch, and light clusters of aggregated carbon nanotubes while varying the amount of sacrificial template material by dry pressing at 25 MPa. The results show that the characteristics of the sacrificial templates, e. g., the rigidity, directly affect the pore characteristics and accordingly determine the permeability of sintered diatomite membranes. Also, we discuss whether the largest pore sizes and average pore sizes of the sintered diatomite membranes reflect the actual permeability appropriately. (C)2013 The Ceramic Society of Japan. All rights reserved.</P>

Synthesis of Li₂SiO₃ using novel water-assisted solid state reaction method

WATANABE, Mizuki,INOI, Jun,KIM, Sun Woog,KANEKO, Tatsuro,TODA, Ayano,SATO, Mineo,UEMATSU, Kazuyoshi,TODA, Kenji,KOIDE, Junko,TODA, Masako,KAWAKAMI, Emiko,KUDO, Yoshiaki,MASAKI, Takaki,YOON, Dae Ho Ceramic Society of Japan 2017 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.125 No.6

<P>Single phase of orthorhombic Li2SiO3 was synthesized via a novel soft-chemical synthesis method, water assisted solid state reaction method at 343-353K for 60 min. The crystal structure of the samples was characterized by X-ray diffraction (XRD) analysis. The scanning electron microscope (SEM) observation revealed that the estimated size of the particles is 50-200 nm. The XRD patterns and SEM images were compared to those of samples by a conventional solid state method at 1173K for 4 h. (C) 2017 The Ceramic Society of Japan. All rights reserved.</P>

Effect of carbon content on the tribological behavior of TiCxN1^|^minus;x films prepared by arc-vapor deposition

NGUYEN, Xuan Hoa,KIM, In-Ki,JANG, Byung Koog,OH, Yoon-Suk Ceramic Society of Japan 2013 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.121 No.1420

<P>The effects of carbon content on the tribological behavior of titanium carbonitride(TiCxN1-x) films have been studied herein. A set of titanium carbonitride(TiCxN1-x) films was prepared by arc ion plating with a pure Ti target and a gas mixture of C2H2/N-2 on a steel substrate. High-definition field-emission scanning electron microscopy (FESEM) was used to investigate the microstructure of the films. The chemical composition of the films was analyzed using both electron dispersion spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analysis. The surface roughness and microhardness of the films were measured using alpha-step profilometer and nanoindenter respectively. The tribology of titanium carbonitride(TiCxN1-x) films was investigated using a ball-on-disc testing method and the wear tracks were observed by low-magnification SEM. The tribological behavior of the films was significantly changed with variation of the C2H2/N-2 gas ratio. A very low friction coefficient (0.07) of titanium carbonitride(TiCxN1-x) film was observed when the C2H2:N-2 gas ratio was about 3:2. (C) 2013 The Ceramic Society of Japan. All rights reserved.</P>

Effect of water vapor on static fatigue behavior of a nickel/yttria-stabilized zirconia composite

MATSUDAIRA, Tsuneaki,JANG, Byung-Koog,KIM, Sun-Dong,WOO, Sang-Kuk Ceramic Society of Japan 2017 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.125 No.5

<P>The effect of water vapor on the mechanical properties of a porous nickel/yttria- stabilized zirconia (Ni-YSZ) composite ( volume ratio of Ni:YSZ = 40: 60) was evaluated at 850 degrees C, a typical operating temperature of a reversible solid oxide cell. Both the flexural strength and static fatigue limit of Ni-YSZ obtained from the static fatigue lifetime under a wet atmosphere (containing 4% H2O) were lower than those under a dry atmosphere. This can be explained by absorption of H2O molecules into YSZ particles, resulting in accelerated crack growth. The fatigue limit of Ni-YSZ was confirmed to be extremely low, corresponding to almost one-third of the flexural strength. (C) 2017 The Ceramic Society of Japan. All rights reserved.</P>