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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 24, Issue 6 - Jun 1987
Volume 24, Issue 5 - May 1987
Volume 24, Issue 4 - Apr 1987
Volume 24, Issue 3 - Mar 1987
Volume 24, Issue 2 - Feb 1987
Volume 24, Issue 1 - Jan 1987
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The Effect of Binder Burnout Time and Heating Rate on the Electrical Properties of Multilayer Ceramic Capacitors
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 207~214
This paper is to determine the effect of binder burnout time and heating rate on the electrical propertries of type II multilayer ceramic capacitors(MLC). The quality of multilayer ceramic capacitor depends suitable on the binder burnout time, which is determined for at least 24 hours in the PVB-binder system. It is suggested that theelectrical properties of multilayer ceramic capacitor is due to the control of heating rate, with the dipole moment density from grain size distributiion. Comparing the fast firing with slow, we observed a small but consistent improvement in the electrical properties.
-Fe2O3 on the Surface of Mica Particles
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 215~222
-Ferric Hydrous Oxide and
-Ferric Oxide were obtained as following processes that Ferric Nitrate solution was adjusted to pH 6-8 with Ammonium Hydroxide, refluxed the Iron precipitate for 1 hr. at 80
, washed it with water and Methanol (95%), dried it to obtain
-Ferric Hydrous Oxide at 60
, and then heated in atmosphere to prepare
-Ferric Oxide for 1 hr. at 450
. Mica particles cleaned with ultrasonicator (45KHz) in water were mixed with Ferric Nitrate solution and treated it to adsorb
-Ferric Oxide on the surface of mica particles by using the abovementioned processes, but the heated temperature was at 500
. The maximum wavelength of reflected light on the surface of mica-
-Ferric Oxide (50%) was appeared at 546nm but -Ferric Oxide free mica only was at 436 nm. The maximum wavelength was shifted to longer when the weight ratios of
-Ferric Oxide to mica was changed from 1% to 50%.
Mechanical Properties of Sintered and HIPed Silicon Nitride
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 223~226
Among many densification routes for silicon nitride, HIP(hot isostatic pressing) is becomming more popular these days, mainly due to the fact that it can produce highly reliable products with superior mechanical properties. This study involves in sintering of silicon nitride followed by HIP which requires no canning. Various property changes curing sintering and HIP are observed and analyzed in terms of microstructural changes. Porosity decrease and enhanced interlocking of grains by HIP are considered to be the major causes for improved mechanical properties of silicon nitride.
Crystallization of Lithium Zinc Silicate Glass System
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 227~234
With the content of ZnO varing from 10.5 to 47.4 wt%, the crystallization of lithium zinc silicate glass was investigated by DTA, XRD, and SEM. In this work P2O5 was used as nucleation agent. The crystallization temperature was found to increase with the content of ZnO and the microstructure of formed crystalling phases was studied through the scanning electron microscopy. According to the XRD analysis, the crystal phases formed are summarized as follows. 1) The major phases are lithium orthosilicate, lithium disilicate and quartz at 10.5 wt% ZnO. 2) Lithium zinc silicate polymorphous and cristobalite occur in the composition varying 21.3 to 30.8 wt% ZnO. 3) At composition containing 47.4wt% ZnO some quantity of willemite is formed.
A Study on the Preparation of Fine Powder and Synthesis of (1-x) ZrO2-xY2O3 Systems
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 235~242
This study was about to make zirconia ceramics with yttria, using spraying precipitation method for the purpose of powder control. The powder properties and the characterization of sintered body, were studied. As the results, 1. The synthesized powder had homogeneity of spherical shape, and average particle size was 2-3 um. 2. Crystallization temperature increased with Y2O3 content. 3. Apparent density of sintered body (fired above 1500
) was higher than 98% of theoretical value in 3 mol% Y2O3 content. 4. High KIC values(19kg/㎣/2) in 3 mol % Y2O3 content resulted from sintering density increasement.
Effects of Aging on Properties of MgO-Partially Stabilized Zirconia
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 243~250
The effects aging on some properties and thermal-shock behavior of zirconia partially stabilized with 9 mol% MgO (9MZ) were studied. 9MZ specimens were aged over
for 12hours subsequently, after sintering at
for 4 hours. Fracture strength(both before and after thermal-shock test), linear thermal expansion, monoclinic fraction and phase transition by XRD, density, galvanic potential and microstructure were measured. Quantitative chemical analysis around the grain-boundary of the specimen aged at
was also conducted by EDX. The aging of 9MZ specimen causes a thermal decomposition of cubic-
into the formation metastable tetragonal-
and MgO. The former increases the residual strength after thermal-shock test and the latter improves the thermal-shock resistance due to thermal conduction through the continuous magnesia phase and the formation of monoclinic phase content in matrix were increased with decreasing the aging temperature from
. Galvanic potential of the aged specimen exhibited a proper emf characteristic.
AC Degradation of BaTiO3 Ceramics
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 251~256
The degradation of barium titanate ceramics was studied under the high AC electric field. At 150
, life time was measured as a function of grain size, controlled by varying sintering time at 1375
and electrical properties, such as AC conductivity, capacitance and dissipation factor, were measured during degradation process. The life time decreased as grain size increased in the range of 2.44-8.23
. The AC conductivity was remained constant and increased suddenly at the last stage of degradation process. The capacitance was slowly decreased and the dissipation factor was slowly increased as the degradaton progressed.
Preparation of the Cobalt Oxide Powder by Hot Petroleum Drying Method
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 257~262
The characteristics of cobalt oxide powders prepared by hot petroleum drying method from the cobalt acetate were evaluated by DTA/TGA, XRD, BET, SEM and density measurement. The cobalt oxide powder could be prepared by hot petroleum drying of the emulsion of cobalt acetate salt solution and the subsequent thermal decomposition of the acetate at 300
. As the concentration of the salt solution and the calcination temperature of the dried powder increased, the surface area of the synthesized powder decreased due to the particle growth, so that after sintering the density and grain size decreased. For the same concentration of the salt solution, the surface area and sinterability of the powder by hot petroleum drying increased in comparision with those by conventional drying.
Microstructure and Electrical Properties of Pb(Mg1/3Nb2./3)O3-PbTiO3-PbZrO3 Ceramics Modified with Yttria
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 263~269
It is investigated that the determination of the correlation between the change of microstructure and electrical properties. Yttria is added to the compositiojn of rhombohedral region in Pb(Mg1/3Nb2./3)O3-PbTiO3-PbZrO3 ternary system. Average grian size, lattice parameters and distribution of yttrium are characterized by XRD, SEM and EDS. Electrical properties are determined by measurement of Curie temperature, piezoelectric properties and hysteresis loops. The results are as follows; 1. Both lattice parameters, a and
, are changed by addition of yttria to the composition of rhomboheadral region in Pb(Mg1/3Nb2./3)O3-PbTiO3-PbZrO3 ternary system and Curie temperature is proportional to the values at (90-
Microstructure and Dielectric Properties of a SrTiO3-based GBL Capacitor
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 270~276
The microstructure and dielectric properties of a SrTiO3-based GBL (Grain Boundary Layer) capacitor were investigated. The 0.6 mol% Nb2O5 doped SrTiO3 was sintered for 3 hr at 1450
in mixed gas(N2/H2) atmosphere. The Nb2O5 promoted the grain growth of the SrTiO3 ceramics was decreased with the amount of Nb2O5. The oxide mixture(PbO, Bi2O3, B2O3) were painted on the reduced specimen and fired at 1000
in air. The penetrated oxide mixture into specimen were located in grain boundaries. A SrTiO3-based GBL capacitor had the apparent permittivity of about 3.0
104, the dielectric loss of 0.01-0.02, and insulating resistance of 108-109
.cm. The capacitor had the stable temperature coefficient of capacitance and exhibited dielectric dispersion over 107 Hz. The capacitance-voltage measurements indicated that the grain boundary was composed of the continuous insulating layers.
Studies on AlF3-(Mg＋Sr＋Ba)F2-P2O5 Glasses II. Effect of MgF2 Contents
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 277~281
The various contents of MgF2 from 0 to 12.5wt% are studied in the AlF3-(Mg＋Sr＋Ba)F2-P2O5 system for the effects of various properties in glasses and the atmosphere of melting was controlled by N2 and Ar gas respectively. Density, refractive index, infrared transmission, thermal conductivity and thermal expansion coefficient of glasses are determined. Density, refractive index and thermal conductivity are decreased, micro-hardness and thermal expansion coefficient are increased according to the increasing of MgF2 contents. Infrared transmittance decreases with increasing the MgF2 contents and it slightly dropped by air than N2 and Ar atmosphere. Other properties are not influenced by atmosphere control.
Diffusion of Ion in Hardened Cement Paste Containing Slag-Siliceous Powder (I) Diffusion of Cl- Ion
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 282~288
Diffusion of Cl- ion in hardened cement paste with slag and siliceous powder such as silica fume and white carbon was investigated. The addition of admixtures reduces the content of Ca(OH)2, which is the main cause of pore formation by corrosive action of sea-water. The addition of admixtures makes the hardened cement paste dense, thereby restricting the diffusion of Cl- ion and improving the resistance to sea-water. Apparence diffusion coefficient of Cl- ion in hardened ordinary portland cement paste was 3.7
/sec, while that for the hardened cement paste with the admixture was 1.2∼3.2
Influences of Sodium Gluconate on the Physical Properties of Portland Cement Pastes and Mortars
Journal of the Korean Ceramic Society, volume 24, issue 3, 1987, Pages 289~295
The changes of physical properties of portland cement pastes and mortars were investigated by addition of sodium gluconate. Flow table experiment and viscosity measurement were took in order to find dispersing effect, and time-dependent changesof viscosity and rates of hydration heat evolution were carried out for the sake of finding retardation effect of hydration. And changes of physical properties of cement pastes and mortars were discussed by setting time, compressive strength and porosity.