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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Ceramic Society
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Journal DOI :
The Korean Ceramic Society
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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 Size of Sintered Body on Resonant and Filter Characteristics in Pb(Sn1/2Sb1/2)O3-PbTiO3 Piezoelectric Ceramics
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 309~314
In this study, the effect of the size of sintered body on resonant and filter characteristics in Pb(Sn1/2Sb1/2)O3-PbTiO3 piezo-electric system were investigated. The attenuation characteristics of ring-dot type and ladder type filter were also investigated. As the size of sintered body was decreased, the resonant characteristic(Fr, Fa) and the center frequency(Fo) were increased. As the poling field was increased, the Kp and bandwidth were increased. The big difference between rign-dot type and ladder type was the sharpness of bandwidth, selectivity and the movement of center frequency.
Fabrication of Doped BaTiO3 by Coprecipitation Method
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 315~320
The Nb doped BaTiO3 was synthesized by coprecipitation method using H2O2 media in region from pH 8 to pH 11. The powder prepared by using this method was crystallized at about 20
and average particle size was controlled by heat treatment. Because of preparation having fine particle and relatively narrow particle size distribution, high performance PTC device was made of these precipitated powders.
The Dielectric and Piezoelectric Properties of (Pb1-1.5xLax)(Ti1-yMny) System
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 321~328
The sintering phenomena, electrical resistivity, dielectric and piezoelectric properties of lead titanate ceramics modified by the partial substitution of La for Pb and Mn for Ti, (Pb1-1.5xLax)(Ti1-yMny)O3 ceramics, have been investigated. In (Pb1-1.5xLax)(Ti1-yMny)O3 system, with increasing lanthanum content, the realtive bulk density increased, but the Curie point and tetragonality (c/a) decreased. The tetragonal-to-cubic phase transition boundary existed in the range of 0.20
Analysis on the Grain Growth of PLZT Ceramics
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 329~334
Kinetics of grain growth in PLZT ceramics during isothermal heat treatment and hot-pressing were investigated and the published data on grain growth were reanalyzed. It was found, in many cases, that the errors were introduced by ignoring the initial grain size. The grain growth of PLZT ceramics was confirmed to follow the parabolic normal growth : D2-Do2=Kt.
Effect of V2O5 Addition on the Microstructure and Electrical Properties of Pb(In1/2Nb1/2)O3-PbTiO3 Ceramics
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 335~340
The change in microstructure and the electrical properties of Pb(In1/2Nb1/2)O3-PbTiO3 Ceramics caused by V2O5 addition were studied. The results are ; 1. interability was increased because the mass transport through the second phase formed by V2O5 addition increased. 2. ith addition of V2O5, tetragonality and Curie temperature increased. The maximum value of kp was observed when 0.5wt% of V2O5 was added. 3. he second phase formed by V2O5 accelerated the grain growth, and existed in grain boundary. Electrical properties were changed by corelations between tetragonality and the amount of second phase.
Electrical Behaviors of SnO2 Thin Films in Hydrogen Atmosphere
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 341~348
Thin films of tin-oxide were prepared by chemical vapor deposition technique using the direct of SnCl4. Resistivity and carrier concentration of deposited SnO2 thin film were measured by 4-point probe method and Hall effect measurement. The results showed the remarkable dependence of electrical properties on the deposition temperature. As the deposition temperature increased, resistivity of deposited film initially decreased to a minimum value of ~10-3
cm at 50
, and then rapidly increased to ~10
. Electrical conductance of these films was measured in exposure to H2 gas. It was found that gas sensitivity was affected combination of film thickness and intrinsic resistivity of deposited film. Gas sensitivity increased with decrease of film thickness. Fairly high sensitivity to H2 gas was obtained for the film deposited at
. Optimum operation temperature of sensing was 30
for H2 gas.
PTCR Effect in Molten Salt Systhesized Barium-Lead Titanate
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 349~356
The PTCR characteristics of (Ba0.8Pb0.2)TiO3 ceramics prepared by the molten salt sysnthesis (MSS) method have been investigated as a function of the amount of Nb2O5 dopant and KCl flux. When the weight ratio of KCl to raw material is 0.8, the resistivity at room temperature decreases with increasing amount of Nb dopant up to 0.6 atom%. It can be explained by compensation for electrons due to Nb+5 ion and holes due to K+ ion. The resistivity of (Ba0.8Pb0.2)(Ti0.994Nb0.006)O3 ceramics at room temperature decreases with increasing the ratio of KCl to raw material up to 0.6, and then increases. These results can be explained by the effect of K+ ion.
The Synthesis of High-purity Zirconia Powders and Its Properties (Compaction and Sintering Behaviro as a Function of Granulation Methods)
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 357~363
Ccompaction and sintering behavior of highly pure PSZ powders were investigated by laying the stress on the granulation processes. The particle size of coprecipitated PSZ powder was so fine that the agglomeration was severely formed during drying and calcing step and by this agglomeration differential sinering was occurred. The methanol dispersion of precipitates was the good method of avoiding severe agglomeration formed during drying process because of small surface tension than water. But perfect deagglomeraton was not possible due to high surface area of powders. So homogenization by granulation was needed, and among the method spray granulation was the most desirable to obtain homogeneous compacts and subsequent flaw-free ceramics.
Mechanical Properties of the Ceramics of the System Al2O3-ZrO2-Y2O3 Prepared by the Precipitation Method
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 364~372
The mechanical properties and microstructure of ceramics of the system Al2O3-ZrO2-Y2O3 sintered at 1
for 2h after powder preparation by the precipitation method from Al2(SO4)3.18H2O, ZrOCl2.8H2O and YCl3.6H2O were investigated. The Al2O3-ZrO2-Y2O3 ceramics sintered at 1
for 2h after mixing alpha-Al2O3 and ZrO2-Y2O3 powders, both were separately precipitated and calcined, were found to have the relative density higher than 97.5% so that the strengthening and toughening mechanisms could be explained mainly as the stress-induced phase transformation. On the other hand, the sintered bodies prepared by co-precipitating the three starting materials were measured to have the relative density lower than 85% so that the degradation of strength were observed above 15 vol% ZrO2 contents due to the high porosity by which the effect of stress-induced phase transformation was assumed to be depressed.
Effects of Crystallization and Seeding on Characteristics of Al2O3-ZrO2 Powder Prepared by a Sol-Gel Method
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 373~379
-Al2O3-15m/o ZrO2 powder was prepared by a sol-gel method from boehmite and zirconium acetate. The transformation temperature of boehmite to
-Al2O3 in the system Al2O3-ZrO2 was increased due to the coupled crystallization. On the other hand, the transformation temperature from boehmite to
-Al2O3-15m/o ZrO2 could be prepared at 110
for 100min. The specific surface area of the product of
-Al2O3-15m/o ZrO2 was 13.2
Nitridation of Silicon Powder Compacts in Air
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 380~384
This investigation includes nitridation phenomena of silicon powder compacts in air. Nitridation reaction condition has been provided with using silicon nitride bed and active carbon additive. Reaction products are Oxynitride,
-Si3N4, Oxynitride(Si2N2O) phase in formed at outer surface layer ofsilicon powder compacts.
-Si3N4 are formed at inner region of powder compacts. Microstructural observation indicates that nitridation mechanism in this work is the same as conventional nitridation mechanism nitrogen gas.
Effect of Binder on the Sintering Characteristics of PZT Ceramics
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 385~389
Effects of binder addition on the porosity, pore size and grain size of PZT ceramics were investigated. The binders were used PVA, PEG and MC, they were added separately and simultaneously. After sintering for 90 min 125
, the porosity and the pore size were determined by using an image processing method. Simultaneous addition of two different binders resulted in the highest sintered density and the large pore size.
Effects of Additives and Atmospheres on the Grain Growth of TiO2 Ceramics
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 390~398
Effects of atmospheres and adidtives on the grain growth of TiO2 ceramics were investigated. In the range of 1300~140
, grain growth was increased in CO2 as compared with O2 atmosphere and the grain boundary migration activation energy was lower than the diffusion activation energy of oxygen ion in TiO2. Also, in the case of addition of oxides, the grain growth was increased by oxides acting as a acceptor andinhibited by oxides acting as a donor. From the above results, when the oxygen vacancy concentration was increased, the intrinsic grain boundary mobility was increased and the pore drag force was decreased due to the rapid densification. Also it seems that the pore was migrated by the surface diffusion rather than lattice diffusion.
A Study on the Preparation of MgO-Al2O3-SiO2 System Ceramic Powders by Spray Pyrolysis Method
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 397~407
Spinel, mullite and cordierite powders have synthesized from Mg(NO3)2.6H2O, Al(NO3).9H2O and SiCl4 solution by spray pyrolysis method. The two-fluid nozzle was used as an atomizer. The powders of sinel and mullite were synthesized above 80
, but the cordierite composition was noncrystalline for all synthersizing temperature. Those noncrystalline powders were crystallized to
-cordierite during calcining at 130
for 2hrs. The synthesized spinel, mullite and cordierite powders seem to be consisted of agglomerated hollow spherical particles. For all powders, the particle size ranged from submicron to about 3
and mean particle size was about 1.4
in diameter. The specific surface area values of spinel, mullite and cordierite powders were maximum for powders prepared at 100
, and those were 45.9, 25.8 and 13.6
Mechanism of Intercalation Compounds in Graphite with Hydrogen Sulfate (II. Study of Intermediate Phase between 2 stage and 1 stage in Graphite Hydrogen Sulfate)
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 408~414
This thesis is 2nd thesis from "Mechanism of Intercalation Compounds in Graphite with Hydrogen sulfate(J. Korea Cer. Soc. Vol. 22. No.6, 1985). We have oxidized natural Graphite flakes(0.1~0.2mm., Kropfm hl passau in Deutchland. S40) with a solution of CrO3 in H2SO4. Whilst persulfate ions were intercalated, too, below 7
, no evidence for intercalation of a peroxo compound was found at 22
. The reaction was interrupted after various times by filtering and washing with concentrated H2SO4. X-ray diffraction showed that the 2nd stage compound had already been formed after 2 minutes. We could only follow further oxidation to the blue stage compound which was completed after 35 minutes. We have found six distinct intermediate stage between 2nd stage and 1 stage. Experiments are described on the formation of intermediate stage color and X-ray diffraction analysis.ysis.
Synthesis of Silicon Nitride from Ethyl Silicate(I)
Journal of the Korean Ceramic Society, volume 25, issue 4, 1988, Pages 415~423
Mixtures of carbon and silica (about 0.46
) which was synthesized by the hydrolysis of ethyl silicate, the molar ratio of silica/carbon was fixed as 1/10(weight ratio : 1/2), were nitrided in the temperature range 135
. The phse of the product Si3N4 was
phase and the morphology was hexagnoal prism and the nitridation reaction was completed in 5 hrs at 150
or 7hrs at 145
. The reaction rate above 150
was diffusion-controlled, following Jander equation. Activation energy Q was derived from the Arrhenius plot and the value was about 101kcal/mol. Axis ratio of Lattice constants(c/a) was 0.726 and unit volume was
3, the larger the molar ratio of carbon/Alkoxide was, the smaller the particle size of