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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 30, Issue 12 - Dec 1993
Volume 30, Issue 11 - Nov 1993
Volume 30, Issue 10 - Oct 1993
Volume 30, Issue 9 - Sep 1993
Volume 30, Issue 8 - Aug 1993
Volume 30, Issue 7 - Jul 1993
Volume 30, Issue 6 - Jun 1993
Volume 30, Issue 5 - May 1993
Volume 30, Issue 4 - Apr 1993
Volume 30, Issue 3 - Mar 1993
Volume 30, Issue 2 - Feb 1993
Volume 30, Issue 1 - Jan 1993
Selecting the target year
Preparation of the LAS Ceramics for Heat Resistance using Metal Alkoxide (I)
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 987~992
In order to synthesize the heat resistance ceramics of LAS system, we studied on preparing the fine powder with homogeneity by sol-gel method using metal alkoxide. Various results were obtained depending on the composition and process. When the amount of H2O added at initial stage is higher than 10mol/
, and when the amount of catalyst is 0.1mol/
, the particle size of synthesized hydrate becomes finer. On condition that partial prehydrolysis time of TEOS is more than 50 hours, the monosized fine powder is obtained(below 1
Nicalon-Fiber-Reinfored SiC Composites Via Infiltration
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 993~998
Nicalon-fiber-reinforced SiC composites were fabricated via polymer solution infiltration/chemical vapor infiltration (PSI/CVI) and CVI. Specifically, data were taken and compared for flexural strength, fracture toughness, and processing time. The two process resulted in comparable mechanical properties, and PSI/CVI process resulted in significantly reduced infiltration time.
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 999~1006
Si3N4(p)-SiC(p) composites were prepared by gas pressure sintering at 190
for 1 hour.
-SiC with average particle size of 0.48
were dispersed from zero to 50vol% in
-Si3N4 with average particle size of 0.5
. Y2O3-Al2O3 system was used as sintering aids. When 10vol% of SiC was added to Si3N4, optimum mechanical properties were observed; relative density of 98.8%, flextural strength of 930MPa, fracture toughness of 5.9MPa.m1/2 and hardness value of 1429kg/
. Grain growth of
-Si3N4 was inhibited as the amount of added SiC was increased. SiC particles were found inside the
-Si3N4 intragrains in case of 10, 20 and 30vol%SiC added composites.
Characterization of Screen Printed
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 1007~1014
YBa2Cu3Ox(YBCO) thick films were prepared by a screen printing of the powders, obtained by a coprecipitation in oxalic acid, on the Y2O3-stabilized zirconia substrates and their superconducting properties were determined. TC, JC and the orientation factor of the thick films increased with increasing temperature up to 103
and then the superconducting properties disappeared with further heat treatments. The optimization of JC was achieved by heating thick films at 103
for 7min. In this case the TC of the thick film was determined to be 87.5K. It was observed that TC of thick films depends on the orthorhombicity and JC is likely governed by a microstructure of YBCO rather than by the orientation factor.
The Study on the Microstructure and Magnetic Properties of Polycrystalline
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 1015~1022
The formation process of polycrystalline YIG(Y3Fe5O12) prepared by conventional method in Fe2O3-Y2O3 system was investigated. Effect of the microstructure of sintered body on electromagnetic properties was also investigated. Orthoferrite (YFeO3) was formed between 900 and 110
. Formation of YIG phase begin at 110
with sharp increased saturation magnetization simultaneously. YIG phase is identified as single phase above 120
. The microstructures and electromagnetic properties of sintered bodies are varied due to calcination condition of starting materials. The sintered YIG of calcined sample at 110
has such magnetic properties as Bs=1580G, BHC=1.89Oe, Tc=570K, ΔH(9.3GHz)=78Oe.
A Study on Synthesis of
by Coprecipitation Process and the Effect of
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 1023~1028
To obtain a single phase of Ba2Ti9O20 at lower temperature than previious other researches. We investigated the effect of Zr substitution for predetermined portions of Ti in Ba2Ti9O20. In this study, the four compounds(x=0, 0.028, 0.048, 0.068) of Ba2(Ti1-xZrx)9O20 were prepared by coprecipitation reaction of BaCl2, TiCl4 and ZrOCl2 with (NH4)2CO3 and NH4OH as the coprecipitating agents and pH regulators, in queous solution. Owing to 4.8 mol% addition, the single phase of Ba2Ti9O20 showing high Q was obtained at 115
which is lower by 25
than the temperature in case of mechanical mixtures of BaCO3 and TiO2.
Effect of MgO on Microstructural Evolution of Alumina Prepared from Hydrosol-Gel Process of Boehmite in Plaster Mold
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 1029~1038
The microstructures of aluminas, included of dissolved CaO as
-alumina seeded pseudo-boehmite hydrosol was gelled in plaster mold and doped of MgO as dipping of calcines(120
-2h) into Mg-nitrate solution, were compared to the one of which additives are excluded during the gellation. It was formed the boundary layer of 300~350
distance from surface to the inside, containing of approximately 500ppm CaO by dissolved Ca from plaster mold. As the MgO addition to the boundary layer with dissolved CaO, the microstructure of the layer was uniformed and inhibited the grian growth, compared to one of that additives be excluded specimen and of MgO doped-inside region. This result was considered as abnormal grain growth and effect of flat boundary formation be appeared by effects of dissolved CaO, were decreased by MgO co-doping.
Preparation of Alumina Powder from Aluminum Salts by Precipitation Method
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 1045~1053
Alumina hydrates were prepared by the neutralization of AlCl3.6H2O solution with NH3 gas diluted with N2 gas. The values of pH in reaction solution influenced the formation of alumina hydrates minerals. Amorphous alumina hydrates, for example, were formed at
-Al2O3. (2) Bayeritelongrightarrowamorphouslongrightarrow
-Al2O3. On the other hand, the shape of alumina hydrates whichw ere prepared by the reacton of Al2(SO4)3.16H2O solution and NH3 gas was spherical, the progress of its phase transformation with increasing temperature was amorphouslongrightarrow
Al2O3 in sequence.
A Study on the Glass-Ceramics of the Cordierite System -the effects of -
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 1054~1058
The effects of TiO2 addition as a nucleating agent on the cordierite glass-ceramics were investigated. The glass compositiion was stoichiometric cordierite composition of 13.7MgO-34.9Al2O3-51.4SiO2(wt%), and TiO2 as a nucleating agent was added by 5, 10 and 15wt% in addition. The optimum amount of TiO2 addition and appropriate heat treatment schedule were determined by using dilatometer, DTA, XRDA and SEM. The composition containing 10wt% TiO2 was proved to be the best among the investigated compositions. And the optimum heat treatment schedule was 840℃-2h for the nucleation and 1140℃-2h for the crystallization. The properties were as follows. The crystallinity was ∼75%, thermal expansion coefficient 33×10-7/℃(25∼700℃), dielectric constant 7.6(1KHz) and Vicker's hardness 5.1GPa.
High Temperature Wear of Plasma-Sprayed
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 1059~1065
The sliding wear behavior of the plasma sprayed zirconia containing 8wt% yttria was investigated over a range of room temperature to 800℃. Both of the friction coefficient and the wear loss increased reaching its maximum at about to 499℃. and then decreased again with increasing temperature up to 800℃. The worn surface at elevated temperature were observed and analyzed by scanning electron microscopy and X-ray diffractometer to study the mechanisms of high temperature wear behavior. Surface morphology of the worn samples changes with temperature. Monoclinic (m)/tetragonal (t) x-ray peak intensity ratio of wear debris and worn surface decreased with increasing temperature. Non-transformable tetragonal (t') to metastable tetragonal (t) phase transformation of worn surface increased with increasing temperature. The results indicate that dehumidification and above phase changes are contributing to the high temperature wear behavior of the plasma sprayed ZrO2-Y2O3 coatings.
Oriented Barium Titanate Ceramics Made from Fiber State Powder
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 1066~1070
When looked upon as a polycrystalline, ceramics have two basic differences from a single crystal. One is that there exist grain boundaries, the other is that the crystal axes of each small crystal are arranged in random directions. But the crystal axes fo small crystals which compose ceramics may be made to have the tendency of being arranged in a specific direction. This is called that the crystal axes are oriented. The degree of the direction arrangement of the crystal axes is called orientation. In order to orient the crystal axes effectively, the fiberous barium titanates were made through KDC method and the ion exchange method. And then they were arranged through pressing, doctor blade, and syringe. As the result of Lotgering evaluation, the sample oriented through syringe showed the highest orientation. After sintering, though the most particles that had been fiberous shaped became global shape viewed through SEM, the orientation of the crystals was reinforced by means of sintering.
Interaction of Alkali Oxide and
Formation and Microstructure
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 1071~1079
Interaction of alkali oxides and SO3 and C3S formation and microstructure was studied using K2CO3 and Na2CO3 as alkali sources and (NH4)2SO4 for SO3. When SO3/K2O=1.43 as mole ratio, K2O and SO3 react to form K2SO4, this phase is immiscible with other oxide melt and thus could not affect C3S formation as well as its microstructure. In a condition of SO3/K2O 1, C3S crystals were round and grown in a much larger size. With addition of Na2O and SO3 by only 1wt% each, C3S formation was strongly hindered. Since C2S was stabilized by Na+ and SO4-2, it could not react to give C3S formation. However in the condition of SO3/Na2O=1.43, a little amount of C3S was formed. It is considered that small amount of Na2SO4 was formed, this phase was immiscible with clinker liquid, and the C3S crystals were formed locally in the liquid part of relatively low Na2O and SO3 compositions. These crystals had irregular and rough surfaces and contained more inclusions than those grown from K2O.SO3 system.
Properties of Residue Compounds Obtained from H2SO4-Carbon Fiber Intercalated Compound
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 1080~1088
The residue compounds of sulfuric acid-carbon fiber system were obtained from P100, M40, TZ307, and T300 fibers. The fibers which easily formed intercalation compound had small change of d002 value, but, large change of diameter of fiber. It was considered that the cracks in carbon fiber were due to the this conflicting result. The resistivities of residue compound of carbon fibers were increased with the large change of diameter of fibers. It is thought that the reason of our results is increasing defects such as crack in fibers. From the UV reflection spectra, it was found that reflectances of residue compounds were all decreased and the residue compounds were more stable than intercalation compounds.
Structure of the
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 1089~1095
-Al2O3 (1100) surfaces were studied with reflection electron microscopy (REM) technique. Severely faceted surfaces were found in the <1120> azimuth. Two methods were applied for indexing the facets. The facets are indexed as (1101) and vicinal facets of (1102), while the macroscopic plane is (1100).
A Study on the Synthesis of Titanium Nitride by SHS(Self-propagating High-temperature Synthesis) Method
Journal of the Korean Ceramic Society, volume 30, issue 12, 1993, Pages 1096~1102
Titanium nitride was synthesized by reacting Ti powder with nitrogen gas using SHS method. In this process, the effects of nitrogen pressure, dilution with TiN, or additiion of titanium hydride(TiH1.924) on the conversion of Ti to TiN were investigated. In particular, much effects were given to solve the problem of the conversion drop due to partial melting and subsequent sintering of Ti parciels, by controlling combustion temperature and combustion wave velocity via mixing Ti powder with TiN or/and TiH1.924. For the diluted titanium powders with TiN, the conversion close to 100% was resulted when the nitrogen pressure was over 8atm and with diluent content of 60wt%, and the self-propagating reaction was not sustained when the diluent content was higher than 60wt%. For samples mixed to be 55wt% in Ti component in the mixture of Ti, TiH1.924, and 45% TiN, the conversion was closed to 100% when the amount of titanium hydride added was over 7wt% and the nitrogen pressure was higher than 5atm. The combustion reaction, however, was not sustained when titanium hydride added was more than 10wt%.