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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
Selecting the target year
Analysis of Production Process of Fine Size Fraction of Korean Kaolin by Ball Mill Grinding II
Journal of the Korean Ceramic Society, volume 24, issue 1, 1987, Pages 1~8
The validity of Alyavdin-Chujyo's Equation was re-examined over the broader milling conditions that those previously examined. Ordinary ball mill grinding with a laboratory scale batch mill (133mmø×144mm length) were selected as the grinding methods. The results show that in ball milling the Alyavdin-Chunjyo's Equation can be applicable over wide grinding time and size range with few exceptions. The validity of which are examined and discussed. The theoretical consideration of the relation between Alyavdin-Chujyo's Equation and size distributiion equation, such as Rosin-Rammler's law, was tried, and it is found that, under the condition of alyardin-Chujyo's relation, the Rosin-Rammler size distribution law can hold.
Effects of Na2O Content on Characteristics of
Journal of the Korean Ceramic Society, volume 24, issue 1, 1987, Pages 9~16
Physical and electrical properties of
-Al2O3 were investigated as function of Na2O content from 6.67 wt.% to 13.19 wt.%. The majority phase is
-Al2O3 and the small amount of
"-Al2O3 exists in the specimens sintered at 1600
for 30 mins. In the case of specimens with 8.54 wt.% Na2O sintered at 1600
, the relative amount of
-Al2O3 phase increases and that of
"-Al2O3 phase decreases with increasing sintering time, and then
"-Al2O3 phase does not exist if sintering time is over 8 hrs. As the Na2O content is increased, the 3-Point MOR and the resistivity are decreased. However, density and 3-Point MOR with increasing sintering time are decreased due to increasing the enclosed pore trapped inside of the exaggerated grains. As the sintering time is increased, the average grain size and the duplexity of microstructure are increased, and the resistivity is slightly decreased.
Preparation of Sr-Ferrite Powders by Hydrothermal
Journal of the Korean Ceramic Society, volume 24, issue 1, 1987, Pages 17~22
This study is to detect the synthetic condition for the formation of Sr-Ferrite(SrFe12O19) by hydrothermally reaction. Mixed suspension of SrCl26H2O and FeCl3 6H2O were fixed on pH and were subjected to autoclavings at various temperature(150∼300
), reaction time(2hrs.∼48hrs.). The Sr-Ferrite powders were synthesized at 150
for 36hrs, 200
for 4hrs and 250
for 2hrs. Synthesized powders were increased particle sizes at longer reaction time and higher reaction temperature. It has hexagonal ferrite M-type structure and has high purity of SrO.5.6 Fe2O3 composition.
Synthesis of Powder of the System Si-Al-O-N from Alkoxides I. Synthesis of Si3N4 and
-Sialon Ultrafine Powders from Alkoxides
Journal of the Korean Ceramic Society, volume 24, issue 1, 1987, Pages 23~32
Synthesis of high purity ultrafine Si3N4 and
-Sialon powders was investigated via the simultaneous reduction and nitriding of amorphous SiO2, SiO2-Al2O3 system prepaerd by hydrolysis of alkoxides, using carbonablack as a reducing agent. In Si(OC2H5)4-C2H5 OH-H2 O-NH4OH system, hydrolysis rate increased with increasing reaction temperature and pH. Pure
-Si3N4 was formed at 1350
for 5 hrs in N2 atmosphere. In Si(OC2H5)4-Al(OC3H7)3-C6H6-H2 O-NH4OH system, weight loss increased as Si/Al ratio decreased. Single phase
-Sialon consisted of Si/Al=2 was formed at 1350
in N2 and minor phases of
-Si3N4, AIN, and X-phase were existed besides theSialon phase at other Si/Al ratios. The Si3N4 and Sialon powders synthesized from alkoxides consisted of uniform find particles of 0.05-0.2
in diameter, respectively.
Phase Relationships of Al2O3-Cr2O3-ZrO2-HfO2 System
Journal of the Korean Ceramic Society, volume 24, issue 1, 1987, Pages 33~40
The investigation includes phase equilibria of Al2O3-HfO2 Cr2O3-ZrO2, Cr2O3-HfO2, Al2O3-Cr2O3-ZrO2, Al2O3-Cr2O3-HfO2, Al2O3-ZrO2-HfO2, Cr2O3-ZrO2-HfO2, Al2O3-Cr2O3-ZrO2-HfO2. In the systems the solubility near the end members has been studied at 1500
, respectively. Selective Compositions were investigated in the area of the guarternary system where the phae relation was examined.
Volume Expansion and Crystal Phase in Solid-Solid Reaction of BaTiO3
Journal of the Korean Ceramic Society, volume 24, issue 1, 1987, Pages 41~46
When barium titanate was synthesized in soild-solid reaction the abnormal expansion occurred from 900
. The equi-molecular mixture of BaCO3 and TiO2 was sintered from 800
on the condition of air, vacuum and CO2 atmosphere. After that the specimens were tested closely with XRD, Dilatometer, SEM and EDS. The result indicated that; 1. The crystal phase which was concerned with expansion of BaTiO3 was Ba2TiO4 as the intermediate crystal phase. 2. The formation of Ba2TiO4 was affected by the firing atmosphere. 3. The expansion occurred when BaTiO3 changed to Ba2TiO4 and pore also expanded by the expansion of BaTiO3 body just as the model of expansion.
Investigation of a Method Measuring Bond에s Work Index of Korean Kaolin by Laboratory Ball Mill
Journal of the Korean Ceramic Society, volume 24, issue 1, 1987, Pages 47~55
The purpose of this work is to establish the basic calibration data for the efficiency of grinding by investigating the Bond's Work Index employing Korean Kaolin as a reference mateial with the laboratory-scale ball mill. A small ordinary ball mill has a dimension of 133 inside diameter and 144mm long. The analysis of the experimental results in this work sets up a equivalent calibration method with the laboratory-scale ball mill to those with special mill. The theoretical expression, derived from the rate equation proposed by Miwa, is obtained to anticipitate the stable revolution number for the next grinding cycle. The proposed equation is more systematic and acurate than lshihara's empirical equation is more systematic and acurate than lshihara's empirical equation for the measurement of gindability of a ball mill.
The Effects of Tetragonality to the Physical Properties of PZT
Journal of the Korean Ceramic Society, volume 24, issue 1, 1987, Pages 56~62
Tetragonal phase PZT ceramics with a tetragonality of c/a=1.027 to 1.041 were sintered at 1275
for one hour. And the directionality of domain arrangement, microstructure, dielectric and aging properties were investigated. With increasing tetragonality, the directionality of domain arrangement of 180
-domain on the surface is smaller than that in the internal part of specimens. Dielectric constants after poling are increased due to the increased internal energy or decreased due to the microcracks created by poling.
Effect of MoO3 Addition and Their Frequency Characteristics in Nb+5 doped Semiconductive BaTiO3 Ceramics
Journal of the Korean Ceramic Society, volume 24, issue 1, 1987, Pages 63~69
Effect of MoO3 additiion on the semiconductive BaTiO3 ceramics doped with 0.2 mole% Nb2O5 and their frequency characteristics have been investigated on the view of intergranular barrier layer model through the observation of changes in their electrical properties. The resistivity increases with the increase of MoO3 addition, but the capacitance, the frequency dependence of capacitance and the effect of positive temperature coefficient of resistivity (PTCR) decrease. It is explained by the possible increase in the thickness of potential barrier due to the formation of insulating layer and thus decrease in the degree of energy band bending. Both the PTCR effect and resistivity decrease with the increase of frequency due to the possible elimination of barrier layer at the grain boundary.
The Effect of C12A7 and OH Group on the Formation of C3A by Sol-Gel Method
Journal of the Korean Ceramic Society, volume 24, issue 1, 1987, Pages 70~76
The effect of C12A7 and OH group on the synthesis of C3A by the sol-gel process using aluminum-sec-butoxide and calcium nitrate was studied. C3A by sol-gel method was compared with C3A obtained by the conventional method with respect to their reactivity of formation and crystal size. The sol-gel process for initial formation of C12A7 and C3A at lower temperature (1100, 1200
) was superior, but that for complete crystallization of C3A at higher temperature (1300, 1400
) was inferior to oxide mixture process. When heat treated under the atmosphere oxygen-free dried nitrogen eliminate the influence of OH group in C12A7, the reactivity of C3A from sol-gel sample incorporated OH group were poor, whereas that from oxide mixture sample showed remarkable effect. The poor crystallization of C3A at higher temperature is presumed to be due to the fact that incorporated OH group in C12A7 formed at lowr temperature might interrupt the diffusion of CaO to C12A7 to from C3A. The crystal size and the hydration characteristics of both C3A obtained by different processes exhibited almost the same results.
The Effect of Seawater on Hydration of Clinker Minerals (I) Effects of SO42- and Cl- ions
Journal of the Korean Ceramic Society, volume 24, issue 1, 1987, Pages 77~85
Hardened cement paste is mainly affected by corrosion of sulphate and chlorine ions in sea water. In this investigation, many specimens were made with the cement clinker minerals such as C3S, C3A, C4AF and their mixture according to cement composition added various blending materials. After the specimens were immersed in 4% MgSO4 and MgCl2 solutions, the product of reaction, the microstructure of specimen and Ca+2 ion leached in the solution were studied. The formation of Ca(OH)2 in the specimen of C3S is reduced relatively by adding pozzolanic admixtures. The chlorine ion is easily diffuse into the C3S specimen and produced CaCl2 compound, and it makes the specimen porous by leaching out itself into the solution. The specimen of C3A, C4AF are broken down by expanding reaction of ettringite and gypsum compound produced in the MgSO4 solution. At a later period, the ettringite is transformed into gypsum and 5MgO.2Al2O3·15H2O. The C3A in the MgCl2 solution combines chlorine ion to form Friedel's salt and prevents the diffusion reaction of chlorine ion into the specimen. Granulated slag shows inferior effect on the resistance of the specimen in MgSO4 solution by forming ettringite and gypsum, but good result in MgCl2 solution. Pozzolanic materials, on the whole, offer noticable effect on the resistance of the specimen in both solutions.