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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Ceramic Society
Journal Basic Information
Journal DOI :
The Korean Ceramic Society
Editor in Chief :
Volume & Issues
Volume 25, Issue 6 - Jun 1988
Volume 25, Issue 5 - May 1988
Volume 25, Issue 4 - Apr 1988
Volume 25, Issue 3 - Mar 1988
Volume 25, Issue 2 - Feb 1988
Volume 25, Issue 1 - Jan 1988
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Effect of MnO2 Addition on Electrical Properties and Microstructure in Pb[Cd1/2W1/2)0.02Zr0.505Ti0.475]O3
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 571~576
The microstructure and electrical properties of 0.02Pb[Cd1/2W1/2)O3-0.505PbZrO3-0.475PbTiO3 with MnO2 addition have been investigated. The amount of MnO2 addition was 0, 0.2, 0.4, 0.6, 0.8, 1wt%, respectively. When MnO2 is added up to 0.2wt%, Mn3+ which is substituted for Ti4+ site make hole and act as a acceptor. When MnO2 is added over 0.2wt% Mn3+ which is substituted for Cd2+ site create electron and act as a donor. The variation of grain size show that it was rapidly increased by 0.4wt% addition of MnO2, and while that in the range of over 0.6wt% addition of MnO2 it was decreased. The solid solution range of MnO2 that assumed in this composition according to the variations of microstructure and electrical properties was 0.4-0.6wt%.
Structural Study of 90K Superconductor Gd1Ba2Cu3O9-x
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 577~584
Gd1Ba2Cu3O9-x has been found to be a high Tc superconductor with a transitiion onset at 91K and zero resistance achieved at 87K. The structure as determined from x-ray diffraction is orthorhombic, with lattice constants b=3.842
, and c=11.684
. The structural similarities between the Gd1Ba2Cu3O9-x compound and the well-studied single phase perovskite, Y1Ba2Cu3O9-x are discussed. A correlation between the observed x-ray spectrum and the effect of oxygen deficiencies in several of the unit cell planes is also discussed.
Preparation of the Fine Alumina Powder from the Synthisized Aluminum-Sec-Butoxide by the Alkoxide Sol-Gel Process
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 585~592
Aluminum sec-butoxide was synthesized from aluminum foil and alcohol. The characteristics of the alumina powder prepared from the synthesized alkoxide by the Yoldas method were studied. As a result of measuring the synthesized aluminum sec-butoxide by GC, the purity of the synthesized alkoxide was 98.7% on the basis of commercial alkoxide and the yield was 78.5%. A127-MASNMR analysis shows that powders dried at 9
-Al2O3 have 6-cordinated structure and
-Al2O3 has 4-coordinated structure. The characteristics of alumina powder prepared from the synthisized alkoxide showed the same characteristics with the alumina powder prepared from the commercial alkoxide.
The Effect of MgO Clinker s Properties on Corrosion of MgO-C Brick
;;;Akira Watanabe;Shigeyuki Takanaka;
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 593~600
The properties of 10 kinds of MgO clinker were investigated to know the effect of MgO clinker's porperties on corrosion of MgO-C brick. For MgO clinker, chemical composition, porosity, density, periclase grain size, and microstructure were examined, while slag corrosion resistance was examined for MgO-C brick. In MgO clinker pore size and it's distribution, periclase grain size, impurities composition and the composition of grain boundaries are more important factors to determine corrosion degree of MgO-C brick than density, potosity and MgO purity.
Effect of SiO2 Addition on Sintering Characteristics in Ytrriastabilized Zirconia Ceramics
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 601~608
The effect of SiO2 addition on sintering characteristics of 8 mole percent yttria-stabilized zirconia ceramics is investigated. As the addition of SiO2 is increased, sinterbility, microstructure, and Vickers hardness of the zirconia ceramic increased but fracture toughness and electrical conductivity are decreased. It is considered that the electrical conductivity decrease with the increase of SiO2 is due to the decrease of defect concentration of ionized oxygen. From the complex impedance measurement, it is shown that the influence of SiO2 is more dominant at the resistivity of bulk region than of grain boundary region.
Sintering of Silicon Carbide by Reaction Bonding and its Characteristics (Effect of Addition of B4C and Y2O3 in Initial Sintering Precess)
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 609~614
This study was carried out to investigate the effects of B4C or Y2O3 additives on the tendency of sintering,
-SiC synthesis and mineral phase changes by reaction bonding of SiC at 145
. At the sintering temperature of 145
, the additives such as B4C or Y2O3 did not improved porosity and bending strength. Added more than 1.5% of Y2O3, 0.5-0.3% of B4C, the formation of
-SiC was increased. At higher temperature above 145
, it seems that the bodies added B4C, contained 3C form of SiC were denser than that of Y2O3 added. Because the transition of 3Clongrightarrow4Hlongrightarrow6H promoted sintering.
Rheological Properties of Si3N4 Suspension and Microstructure of Slip Cast Si3N4
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 615~622
To develope good slip and microstructure of Si3N4 the knowledge of the interaction of particles in liquid systems is required. In this work polyethyleneimines was tested as a stabilizer for Si3N4-water system. The stability of slip dispersed with polyethyleneimines was good over a wide range of pH and concentrated slips with low viscosity could be cast. This work comprises a systematic investigation including determination of electrical mobility in order to estimate the particle surface charge, determination of sedimentation rate, as well as measurements of the viscosity as a function of dispersants, pH and shear rates. The influence of deflocculation on the microstructure of slip cast Si3N4 was discussed.
Effect of Frit and Sintering Conditions on the Microstructure and Electrical Property in Ag and Ag/Pd Thick Film Conductors
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 623~630
As a function of the composition and content of frit, the electrical property of Ag and Ag/Pd thick film conductors were investigated with microstructure. With increasing sintering temperature in Ag-frit thick film conductors, electrical sheet resistivity decreased, but again increased above 80
. And when frit contents is 5wt%, compact and homogenious microstructure can be obtained, then electrical sheet resistivity has minimum value. In Ag/Pd-frit film conductor, the electrical sheet resistivity decreased with increasing sintering temperature. The system which having frit with low softing point has lower sheet resistivity then to add high softening point frit.
Effect of Ca/P Mole Ratio on the Precipitation and Powder of Hydroxyapatite Synthesized by the Wet Method
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 631~638
Effect of Ca/P mole ratio on the precipitates and powder properties of hydroxyapatite was investigated. Powder and precipitates of hydroxyapatite were synthesized by the reaction of Ca(NO3)2.4H2O and (NH4)2 HPO4 solutions at room temperature. The pH value and compositions (Ca/P mole ratio) in starting solutions were 11 and 1.64-1.79(or 1.85), respectively. Rodlike hydroxyapatite precipitates were agglomerated together. The average agglomerated particle size was ranged from 2-8
. Among compositions, the minimum agglomerated particle size was shown at the Ca/P mole ratio 1.75. CO2 was contained in hydroxyapatite powders and these ultrafine powders had poor crystallinity. The specific surface area and specific total pore volume of hydroxyapatite powders were 104-137
/g and 0.396-0.467cc/g, respectively. When the Ca/P mole ratio was 1.75, these values were the maximum. And water content increased with the Ca/P mole ratio(Ca/P mole ratio>1.67). In most cases, hydroxyapaite was stable to 130
. However, in the case of Ca/P mole ratio 1.64, hydroxyapatite was changed to
-whitlockite at 120
Dielectric Properties of Sr(Mg1/3Nb1/3)O3-Ba(Mg1/3Nb2/3)O3-Ba(Mg1/3Ta2/3)O3 Solid Solution
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 639~644
The physical and dielectric properties of complex perovskite compound Sr(Mg1/3Nb1/3)O3-Ba(Mg1/3Nb2/3)O3-Ba(Mg1/3Ta2/3)O3(BMT) system were investigated as a function of composition. As the mole ratio of BMN was increased, lattice parameter ratio c/a was slightly increased, and density was increased in SMN-BMN system. However, in BMN-BMT system, lattice parameter ratio c/a and density were decreased with increasing the mole ratio of BMN. Dielectric constant, dielectric loss at
and 100kHz, and temperature coefficient of resonant frequency, the dependence of temperature in capacitance were increased with increasing the mole ratio of BMN in SMN-BMN-BMT system. These result can be explained according to the degree of order=disorder and dielectric constant.
Microstructure and Electrical Characteristics of ZnO-Bi2O3 Ceramics
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 645~654
The microstructure and electrical characteristics of ZnO-Bi2O3 ceramics containing 5mol% Bi2O3 have been studied in relation to sintering temperature and mode. The distribution and thickness of Bi2O3 intergranular layer was varied with sintering temperature and mode. Intergranular layer was more homogeneous with increasing sintering temperature, when sintering by direct heating and rapid cooling mode showed the best distribution of intergranular layer. These microstructural changes affected electrical characteristics directly, at 140
and C mode obtained high value of electrical resistivity and nonlinear exponent. Varistor voltage decreased with increasing sintering temperature, increased with decreasing holding time at high temperature. Barrier voltage obtained by calculation was about 1.5V.
A Study on the Purification Process of Alumina by Powder Technics
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 655~664
As a part of study to establish the industrial process for manufacturing high purity alumina powder which is largely used as fine ceramics, an adsorption method using a silica-containing material which can absorb to eliminate a major impurity, Na in aluminum hydroxide as a raw material has been studied. It is confirmed that the primary property of powder such as the particle size of raw material and that of silica-containing material plays a great important role in the purification process.
Characterization of Glasses by Ion-Exchange(II) : Behavior of Mechanical Properties
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 665~670
The behavior of mechanical properties of ion exchanged glasses was investigated in this study. The used glasses were soda-lime-silica glasses that were produced by float process. The maximum values of the bending strength and the curvature depth are 45Kg/
and 8.6mm respectively treated at 45
for 6h, which are 4.4 times and 3.3 times higher than parent glass. In the case, the thermalshock resistance ΔT is 335
that is 205
higher than parent glass, which is the maximum values in this study. The maximum values of the surface microhardness is 490Kg/
in case of 43
for 4h. It is also found out that annealing points are increased linearly with increasing the amount of K+ ion exchange independent of treatment temperature. Furthermore, the present work shows that the ion exchange strengthened glasses are more effective than the physical tempering glasses ; the bending strength and the curvature depth are 1.8 times and twice higher respectively.
Preparation of Ba2Ti9O20 by Coprecipitation Method
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 671~676
Preparation of high purity ultrafine Ba2Ti9O20 powder was investigated by coprecipitation method. Formation of Ba2Ti9O20 powder from precipitate of coprecipitation takes place at 120
, which is 20
lower than that from mechanical mixtures of BaCO3 and TiO2. This is apparently due to the nature of the compounds formed by the reaction of mixtures of aqueous solutions of BaCl2 and TiCl4 with an ammoniacal solution of ammonium carbonate and ammouium hydroxide. In this method, the Ba2Ti9O20 powders show low callcining and sintering temperature and it has good sintering and dielectric constant at room temperature.
Preparation of Monodispersed Titania from TPOT
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 677~684
Titania powders were obtained from the various hydrolysis condition the variation of Alkoxide, water/Alcohol, REaction, Temp., reaction time and solvent system were investigated. In this result, spherical monodisperesed titania gel powders(≒0.7
) were obtained using EtOH(as solvent), and this method had rapid reaction time compare with iso-PrOH(as solvent).
Improved Clay Process for Builder-grade Zeolite Synthesis by Acidic Benification
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 685~693
From leaching of Korean native halloysite with hot sulfuric acid, active species of siliceous aluminosilicate are obtained as residue, which gives the mole ratio of SiO2/Al2O3 10 and substantially removes most acid-soluble impurities. By dissolving the residue in sodium hydroxide at an ambient temperature sodium silicate solution is prepared, this is used for zeolite synthesis as one of starting materials. In order to prepare zeolite Type 4A thereform, addition of a proper aluminum source is made so that the composition of the reactant materials may be of the following mole ratios : Na2O/SiO2=1.2-1.5, SiO2/Al2O3=1.8-2.0 and H2O/Na2O=34-45 By careful control of ageing time and temperature, subsequent crystal growth is induced into microfine zeolite 4A, which gives optimum particle size distributjion being suitable for detergent builder. The zeolite products thus obtained and highly competitive with those from the use of the refined clay in comparison of their calcium exchange capacity, whiteness and particle size distribution. The present method shows a marginal advantage over the existing procedures requiring neitherseparate purification nor calcinating otherwise necessary for the raw clay ores in use.
Variations of Ferroelectric Properties by Unit Cell Distortion of Pb(Zr, Ti)O3-Pb(Co, Nb)O3 Solid Solution in Morphotropic Phase Boundary
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 694~698
Pb(Zr, Ti)O3-Pb(Co, Nb)O3 systems were investigated by x-ray diffraction method. System contains rhombohedral, tetragonal, and pseudocubic structures at room temperature. Crystal symmetry was changed from 4-fold symmetry to 3-fold symmetry by substituting Pb(Co1/3, Nb2/3)O3 ; PCN, to Pb(Zr0.52, Ti0.48)O3 ; PZT. As the substituted PCN concentration was increased, an increase in a-axis direction and a decrease in c-axis in the perovskite structure were occurred simultaneously, so that the crystal symmetry was changed into such way. In the higher sinteringtemperatures, the unit cell distortions occurred rather in the lower substitution range of PCN. The ferroelectric properties were maximized at the region that tetragonal and rhombohedral or pseudocubic structures were coexist.
Domain Structures of LiNbO3 Single Crystals Grown by Czochralski Method
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 699~703
Domain structures of LiNbO3 crystals grown by Czochralski method were examined according to the growth axis and the rotational speed of crystals. Ring shape and split domain structures were revealed in Z-axis and Y-axis grown crystals respectively. It was found that the domain structures of grown crystals were closely related to the solid-liquid interface shape during growth.
Mechanical Properties of the Pressureless Sintered Al2O3-SiC Composites(2) : Dispersion Effects of SiC Whisker
Journal of the Korean Ceramic Society, volume 25, issue 6, 1988, Pages 704~712
In order to investigate the effect of the second phase on Al2O3 matrix, SiC whisker was dispersed in Al2O3 matrix as a second phase over the content range of 5vol% to 20vol%. To this mixture, Y2O3 or TiO2 powder was added as a sintering additive before isostatically pressing and pressureless sintering at 1800-190
for 90min in N2 atmosphere. With increasing SiC whisker content, relative densities of composites were decreased and the grain growth of Al2O3 was restricted. When Y2O3 was added as a sintering aid the sintering temperature was 180
, the maximum values of flexural strength, hardness and fracture toughness were 537MPa, 12.1GPa, 3.7MPa.m1/2, respectively. However, when the sintering temperature was elevated to 190
, maximum values of flexural strength, hardness and fracture toughness were 453MPa, 17.5GPa, 4.9MPa.m1/2, respectively. Improved mechanical properties are assumed to be attributed to the crack deflection by the second phase SiC whisker and whisker pullout mechanism.