Influences of underlayers on structure of TiO2 thin films prepared by radio frequency magnetron sputtering

하재근 CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI 2010 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.118 No.1373

In situ CCVD synthesis of carbon nanotubes within zeolite crystal coated porous ceramic foam

MAZUMDER, Sangram,ZHAO, Wei,PARK, Jung Gyu,SARKAR, Naboneeta,KIM, Sukyoung,KIM, Ik Jin CERAMIC SOC OF JAPAN 2015 JOURNAL- CERAMIC SOCIETY JAPAN Vol.123 No.1438

<P>In this study, consolidated zeolite crystal coated porous ceramic foams containing a large quantity of carbon nanotubes (CNTs) within micro-metre sized pores were prepared. An alumina-silica porous ceramic body, having an average pore size of less than 100 mu m, was produced by the direct foaming technique. Well-shaped zeolite crystals having an average size of 180 nm were synthesized and homogeneously coated on the porous ceramic body by an in situ process. An Fe-supported zeolite/ceramic matrix, which is used for CNT synthesis, was prepared using ion-exchange by immersing the zeolite-coated porous ceramic body into FeCl2 aqueous solution. The CNTs were synthesized by a catalytic chemical vapour deposition (CCVD) process for four different reaction times. Both acicular-shaped and randomly bundled networks of multi-walled carbon nanotubes (MWCNTs) were synthesized using these different reaction times. Moreover, the yield of CNTs produced showed a tendency to increase with increasing reaction time. (C)2015 The Ceramic Society of Japan. All rights reserved.</P>

Development of flexible solid electrolyte with high ion conductivity

KIM, Eun-Hee,YEO, Jeong-Gu,YANG, Seung-Cheol,CHOI, Jiyeon,JUNG, Yeon-Gil CERAMIC SOC OF JAPAN 2014 JOURNAL- CERAMIC SOCIETY JAPAN Vol.122 No.1428

<P>The hybrid electrolyte (HE) was prepared through the mixing of cation-exchanged polymer and ceramic electrolyte material for providing a certain flexibility to solid electrolyte (SE). To adequately utilize features of the HE with valuable ion conductivity, the electrolyte particles should be uniformly mixed with the polymer in the HE. To do that, the mixing was performed in an aqueous solution. The elasticity and hardness of each film prepared were slightly improved by increasing the contents of the electrolyte material. The ion conductivity of the HE showed the similar value with that of the pristine SE in spite of the addition of the polymer in a high level of 97.5 wt.%, resulting from the peaceful mobility of ion through the polymer, indicating that the electrolyte particles were uniformly dispersed in the polymer. As a result, the HE could be applicable to a flexible SE in a secondary battery. (C) 2014 The Ceramic Society of Japan. All rights reserved.</P>

Microstructural evolution of Si₃N₄ ceramics from starting powders with different α-to-β ratios

LEE, Hyun Min,TATAMI, Junichi,KIM, Do Kyung CERAMIC SOC OF JAPAN 2016 JOURNAL- CERAMIC SOCIETY JAPAN Vol.124 No.8

<P>Microstructural evolution of Si3N4 ceramics and thermal/mechanical properties were investigated with respect to the initial alpha-to-beta ratios of the starting powders. The fast growth of elongated beta-grains was observed in the alpha powder, while the growth of relatively equiaxed grains occurred in the beta powder. In the cases where alpha/beta mixed raw powder was used, exaggerated bimodal microstructural evolution occurred as a result of the abnormal grain growth. These microstructural variations of the Si3N4 had a significant influence on the mechanical and thermal properties, such as strength, fracture toughness and thermal conductivity. The bimodal microstructure, which consisted of large elongated grains surrounded by fine matrix grains, resulted in both high flexural strength and high fracture toughness. Controlling the microstructural evolution, resulted in a high thermal conductivity of 86W/mK, a high flexural strength of 912 MPa, and a high fracture toughness of 7.88 MPa. m(1/2) from alpha/beta mixed raw powder. The achievement of both high thermal and mechanical properties of Si3N4 ceramics was highly essential for thermal management applications. (C) 2016 The Ceramic Society of Japan. All rights reserved.</P>

Electrically and thermally conductive SiC ceramics

KIM, Kwang Joo,LIM, Kwang-Young,KIM, Young-Wook CERAMIC SOC OF JAPAN 2014 JOURNAL- CERAMIC SOCIETY JAPAN Vol.122 No.1431

<P>Electrically and thermally conductive SiC ceramics were fabricated by hot-pressing beta-SiC, 2 or 4 vol% TiN, and 2 vol% Y2O3 powder mixtures in a nitrogen atmosphere. X-ray diffraction data indicated that the specimens consisted mostly of beta-SiC grains and traces of alpha-SiC and Ti2CN clusters. Highly-conductive Ti2CN clusters segregated between SiC grains contributed to reduce the electrical resistivity of the TiN-doped SiC specimens. The high thermal conductivity of the TiN-doped SiC specimens was attributed to the lack of solubility of Ti and Y in the SiC lattice and the suppression of a massive beta ->alpha phase transformation in SiC. The electrical resistivity and thermal conductivity of the SiC with 2 vol% TiN specimen were 2.4 x 10(-3) Omega.cm and 174.1 W/m.K, respectively. (c) 2014 The Ceramic Society of Japan. All rights reserved.</P>

Successful preparation of self-setting particle-stabilized zeolite 13X foams

HA, Jang-Hoon,JUNG, Da-Woon,AHMAD, Rizwan,SONG, In-Hyuck CERAMIC SOC OF JAPAN 2014 JOURNAL- CERAMIC SOCIETY JAPAN Vol.122 No.1424

<P>Zeolites are commonly used as adsorbents for a wide range of industrial applications. Recently, to alleviate the pressure drop and mass-transfer problems when zeolites are used as pellets in a packed bed system, the need for a self-standing zeolite foam has grown. Therefore, in this study, a zeolite 13X wet foam was stabilized by zeolite 13X particles that were rendered partially hydrophobic by propyl gallate, mixed with a commercial calcium aluminate cement, and then self-set. A self-setting particle-stabilized zeolite 13X foam contains primary macropores with a size range of approximately 200 to 400 mu m formed by zeolite 13X particles that are irreversibly adsorbed at liquid-gas interfaces as well as secondary inherent micropores. In addition, we investigated the pore characteristics of the self-setting particle-stabilized zeolite 13X foams by scanning electron micrography, mercury porosimetry, physisorption analysis, and capillary flow porosimetry. (C) 2014 The Ceramic Society of Japan. All rights reserved.</P>

The preparation and characterizations of the diatomite-kaolin composite support layer for microfiltration

HA, Jang-Hoon,LEE, Jongman,SONG, In-Hyuck CERAMIC SOC OF JAPAN 2015 JOURNAL- CERAMIC SOCIETY JAPAN Vol.123 No.1440

<P>Recently, porous ceramic membranes have become a subject of significant interest due to their outstanding thermal and chemical stability. To reduce the high manufacturing costs of these porous ceramic membranes, recent research has focused on the utilization of low-cost natural materials. Therefore, in this paper, we report the results of an attempt to prepare a diatomite-kaolin composite support layer that could effectively filter the ISO 12103-1 A3 test dust while exhibiting acceptable water permeability. The pore characteristics of the specimens were studied by scanning electron micrography, mercury porosimetry, capillary flow porosimetry, and a dead-end microfiltration system with particle counters. (C) 2015 The Ceramic Society of Japan. All rights reserved.</P>

Effects of melting temperature on cerium oxidation state and crystallization on catalytic properties in cerium phosphate glasses

KIM, Ju-Hyeong,RYU, Bong-Ki CERAMIC SOC OF JAPAN 2017 JOURNAL- CERAMIC SOCIETY JAPAN Vol.125 No.3

<P>The effect of the melting temperature on the cerium oxidation state and crystallization of cerium phosphate glasses with a molar composition 30CeO(2)-70P(2)O(5) was investigated. Ce3+ and Ce4+ ion concentration changes in the glass attributable to the melting temperature were investigated by X-ray photoelectron spectroscopy analysis. The crystallization kinetics of the glasses and the activation energy for crystallization were evaluated under non-isothermal conditions using differential thermal analysis (DTA) performed at different heating rates. Each DTA curve exhibited one exothermic peak associated with the crystallization of the glass. The crystalline phase was identified as CePO4 via X-ray diffractometry analysis. The Kissinger and Marotta methods were used to calculate the local activation energies for the glass samples. The amount of precipitated CePO4 with heating at 890K increased as the melting temperature (or Ce3+) increased. The catalytic properties were studied by thermogravimetric analysis, which showed that a greater amount of precipitated CePO4 led to poorer catalytic properties of the glass. (C) 2017 The Ceramic Society of Japan. All rights reserved.</P>

Structural, thermal, and chemical properties of boron oxide-doped molybdate glass for use as a lead-free low-temperature sealing material

SHIN, Jae-Young,RYU, Bong-Ki CERAMIC SOC OF JAPAN 2017 JOURNAL- CERAMIC SOCIETY JAPAN Vol.125 No.12

<P>For lead-free low-melting sealing materials, the boron oxide alkali molybdate glass system was investigated with different boron oxide contents between 0 and 8 mol%. The glasses were characterized using differential scanning calorimetry, and infrared spectroscopy, and by their dissolution rates and densities. As the boron oxide contents increase, the glasses maintain their low temperature properties (T-g under 175 degrees C), and new network formers of [BO3] triangular units and [BO4] tetrahedral units appear. The glasses possess MoO4, MoO6, BO3 and BO4 groups as basic structural units, and existing weak Mo-O-Mo bridge bonds convert into strong Mo-O-B bridge bonds. As a result, chemical durability is improved. (c) 2017 The Ceramic Society of Japan. All rights reserved.</P>

Texture-controlled hybrid materials fabricated using nanosecond technology

CHO, Hong-Baek,NAKAYAMA, Tadachika,HUYNH, Minh Triet Tan,NGUYEN, Son Thanh,JIANG, Weihua,SUZUKI, Tsuneo,SUEMATSU, Hisayuki,NIIHARA, Koichi,SHIN, Jung Ho,CHOA, Yong-Ho CERAMIC SOC OF JAPAN 2016 JOURNAL- CERAMIC SOCIETY JAPAN Vol.124 No.3

<P>The controlled assembly of micro- and nano-ceramic fillers in polymer nanocomposites provides robust properties such as wetting, adhesion, thermal conductivity, electrical insulation and optical activity, and enable the extended application of these hybrid materials as thermal interfacing materials in microelectronics and for energy conversion. However, the required properties can only be obtained either by homogeneous mixing or by anisotropic orientation of a large amount (> 50 vol.%) of expensive fillers, which is economically inefficient. Here we propose a strategy for tuning the orientation and assembly of ceramic boron nitride nanofillers in a polymer nanocomposite using a small amount (< 5 vol.%) of filler to enhance thermal conduction. The texture of the BN fillers is tuned by application of a nanosecond pulse electric field and a superconductor magnetic field (10 T); the three-dimensional structure of the products was analyzed using 3-D X-ray CT scanning. The enhanced anisotropic orientation and thermal properties of the products were assessed as a function of the structural variation of the boron nitride fillers in the polymer. (C) 2016 The Ceramic Society of Japan. All rights reserved.</P>