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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
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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
Mechanical and Tribological Properties of
-Sialon/SiC Whisker Composites
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 785~790
Sialon ceramics are presently seen as promising materials with high hardness, strength, fracture toughness and corrosion resistance for friction and wear applications. The objective of present work is to improve of mechanical properties and wear resistance of
-Sialon(x=0.4) by addition of SiC whisker.
-sialon(x=0.4)/SiC whisker composites were obtained by hot-isostatic pressing at 173
for 1 hour under 1757Kg/
N2 pressure after pressureless sintering the mixture of Si3N4, Y2O3, AlN at 1780~180
for 3~5 hours in N2 atmosphere. As the amount of SiC whisker content increased, relative density and hardness were decreased, however fracture toughness, bending strength and tribological properties were improved. Tribological properties of
-Sialon/15 vol% SiC whisker composite were improved in spite of its low mechanical properties.
Electro-Magnetic Properties of Mn-Zn Ferrite Single Crystal with Small Variation of
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 791~796
The electro-magnetic properties of the Mn-Zn ferrite single crystal with small variation of Fe2O3 concentration at the high permeability composition, 53mol% Fe2O3-28.5mol% MnO-18.5mol% ZnO, have been studied for the VCR magnetic head application. With the increase of the Fe2O3 concentration, the Fe2+ concentration increased, the specific resistivity decreased, the secondary maximum permeability shifted to the lower temperature, and the initial permeability decreased. It was concluded that the small variation of
0.5mol% Fe2O3 concentration greatly affected the electro-magnetic properties of Mn-Zn ferrite single crystals. At the composition of 53mol% Fe2O3, the initial permeability was comparatively high (650 at 5MHz) and its temperature dependence was small.
Study on the Deintercalation of
--Intercalated Graphite Fiber
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 797~802
Graphite fiber intercalated compound was deintercalated at
, 65% of humidity and its deintercalated compound was discussed, based on the X-ray diffraction analysis, electrical resistivity measurement, and UV/VIS spectrometer measurements. During deintercalation, the structure was changed in orderlongrightarrowdisorderlongrightarroworder, and resistivity was decreased in the disorder state of the structure, which reflectance minimum of the UV/VIS spectrum ranged from 660 to 750nm (1.88~1.65eV).
Effect of Pb Content on the Phase Transformation of Sputter-Deposited PZT Thin Film During RTA
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 803~810
PbxZr0.4Ti0.6O3 thin films were prepared by reactive co-sputtering and annealed by RTA(Rapid Thermal Annealing) process. Effect of Pb content in PbxZr0.4Ti0.6O3 films on the phase transformation was intensively studied. It has been found out that depending on the Pb content as well as RTA temperature, crystal structure of PbxZr0.4Ti0.6O3 films change greatly. It turned out that transformation temperature for perovskite can be lowered and the width of transition temperature region was reduced by increasing Pb content in the film. And the lattice was expanded with increasing Pb content. With increasing RTA temperature, as-deposited phase was transformed into perovskite through three different transformation paths depending on Pb content. It was confirmed that activation energies for nucleation of perovskite structure are much larger than those of its growth.
Control of Microstructures and Properties of Composites of the
Composites Prepared by the Solution Infiltration Method
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 811~818
Al2O3/ZrO2-Spinel composites were prepared by infiltrating magnesium sulfate solution into the porous preform made from Al2O3-20wt% ZrO2 composite powders derived through an emulsion route. The microstructure and composition of the modified composites could be controlled by manipulating the presingtering temperature of the preform, infiltration time, and so on. It was found that spinel phases were concentrated near the surface than in the interior of the Al2O3/ZrO2-Spinel composites infiltrated for 6hrs, while spinel phases were uniformly distributed in the comosites infiltrated for 2 days. The relative density and fracture toughness of the composite infiltrated for 6 hrs were 98.6% and 7.2MN/m3/2, respectively.
Selective Sensing of Carbon Monoxide Gas in CuO banded ZnO Ceramics
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 819~822
The purpose of this paper is a investigation of sensing mechanism for the carbon monoxide gas in CuO infiltrated ZnO ceramics. Potential barriers between CuO and ZnO can explain the selective sensing of carbon monoxide gas in the physically contacted CuO/ZnO ceramics. A specimen having no potential barrier between CuO and ZnO was prepared to see whether the gas sensing mechanism is related to the potential barrier. CuO and ZnO was prepared to see whether the gas sensing mechanism is related to the potential barrier. CuO was painted on the non electrode sides of ZnO ceramics. The CuO painted ZnO ceramics showed that the sensitivityfor the carbon moxnoxide gas was 1.3 times as high as that for the hydrogen gas. It is almost same gas sensitivity as that of the CuO infiltrated ZnO ceramics.
Control of Matching Frequency of Ferrite Composite Microwave Absorber Consisted of Two Kinds of Ferrites
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 823~828
The performance of ferrite composite microwave absorber has been evaluated as the matching frequency, the matching thickness and the band width. Especially, matching frequency is very important in application of microwave absorber because it determines operating frequency range. In this study, the ferrite composite microwave absorbers consisted Ni-Zn ferrite and Zn2Y ferroxplana were prepared in order to control matching frequency. Then, the variation of the material constants and microwave absorbing characteristics were investigated with various ferrite mixing ratio. The material constants of ferrite composite microwave absorber could be controlled by variation ferrite mixing ratio. Therefore, it was confirm that matching frequency of microwave absorber could be shifted by control of material constants.
Homogeneous Mixing of Si3N4 with Sintering Additives by Coprecipitation Method
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 829~837
Chemically and geometrically homogeneous mixing of Si3N4 powders with sintering additives(YAG, 3Y2O3
5Al2O3) was attempted via coprecipitation method. X-ray dot maps for the additive elements(Al and Y) showed that the additives are evenly distributed in the powder mixture prepared by coprecipitation method(CP). TEM observation of the coprecipittion-treated Si3N4 powders revealed that they are covered with extremely fine crystallites of additive. The shift in isoelectric point(IEP) of Si3N4 powders from pH 6.7 to pH 7.9 after coprecipitation mixing gave another evidence for coating of Si3N4 powders with YAG additives. SIMS analysis for composition on the surface and in the matrix of mixed powders showed that the YAG additives are highly enriched on the surface of coprecipitation-treated Si3N4 powders. Especially when a small amount of additive was used, the effect of homogeneous additive distribution on densification was preceptible: After pressureless-sintering of powder compacts containing 5 mol% YAG at 1800
for 0.5h, a sintered density of 96.5% theoretical was obtained from the specimens prepared bycoprecipitation in comparison with 93.8% from the mechanically-mixed one.
Effects of Organic Substances in the Preparation of Porous Silica Glass by the Sol-Gel Process
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 838~844
To control the pore size of silcia gel, formamide (FA), N,N-dimethyl formamide (DMF), polyethylene glycol (PEG) and polyacrylic acid (PAA) were added in the sol-gel process from starting solution with tetramethyl orthosilicate (TMOS). The gels were characterized using porosimeter, TG-DTA and SEM. As a result, the more contents of FA and PAA was increased the more gelation time was decreased, also the more contents of DMF and PEG was increased the more gelling time was increased. The mean pore size of gels was larger in the order of PAA, DMF, FA and PEG. And the mean pore size of porous silica glass was 59.0
, respectively, heated at 75
Synthesis and Characterization of Cordierite Glass-Ceramics for Low Firing Temperature Substrate; (III) Fabrication of substrates by tape casting process
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 845~851
Low firing temperature substrate were synthesized through tape casting and sintering of glass with cordierite composition and then their properties were investigated. Even though the dielectric properties and XRD patterns of substrates, obtained by tape casting and sintering at 900~100
for various periods, were similar to those of substrates obtained by dry pressing, the sinterability was enhanced. The substrates were thin and the size was 0.6
50mm. From the results of dielectric properties, the sinterability and X-ray diffraction pattern, the proper condition for cofiring process with conductor, Cu, was 90
for 1h. The properties of the substrate are as follows; the dielectric constant was 5.31(at 1MHz), the dissipation factor was 0.0028, the apparent porosity was 0.28% and the main crystalline phase was
Effects of Impregnation on the Manufacture of High Density Carbon Materials
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 852~858
The effect of coal tar ptch-impregnated carbon materials which were made from petroleum coke was investigated at various pressure time and impregnation-sintering cycle. As a result, density and bending strength of the carbon materials were remarkably increased in the condition of pressure times of 5hrs and of the cycle of 3rd times. And the value of d002 and Lc of the graphitic carbon sintered at 230
The Effect of Mechanical Stress and Electric Field on the Morphotropic Tetragonal and Rhombohedr Phase Boundary in PZT System : Thermodynamic Consideration
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 859~865
Morphotropic tetragonal and rhombohederal phase boundary(MPB) in PZT system was calculated and the effect of mechanical stress and electric field on the MPB was examined using phenomenological thermodynamic theory proposed by Devonshire. Mechanical stress and electric field was calculated to change free energies of phases and shift MPB. The stable composition range of the phase, of which spontaneous strain and spontaneous polarization aligned to the direction of tensile stress or electirc field, was expanded.
Electrical Properties of semiconducting
-based Critical Temperature Sensors
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 866~870
For VO2-based sensors applicable to temperature measurements and optical disk materials by the nature of semiconductor to metal transition, the crystallinity and temperature vs. resistance characteristics were investigated as a function of the heat treatment temperature. The bead-type sensors were prepared through typical sensor fabrication processing and heat-treated at 40
, respectively, for 30 minutes in H2 gas atmosphere. As results of the temperature vs. resistance measurements, the electrical resistance in the phase transition range was decreased by 102 order for the VO2 sensor and by 103 order for the V71P11Sra18 system. It was estimated that the hysteresis, temperature vs. resistance, and current vs. voltage characteristics of the V71P11Sr18 system could be utilized for commericialization as a temperature sensor.
Formation and its Microstructure
Journal of the Korean Ceramic Society, volume 30, issue 10, 1993, Pages 871~879
Effects of K2SO4 and Na2SO4 on C3S formation and its microstructure were investigated. C3S formation was not influenced by addition up to 6.0wt% of K2SO4 as SO3 base, however it was prevented by only 1.0wt% of Na2SO4 addition. C3S prevention by added Na2SO4 was the reason why C2S stabilized by Na+ and SO42- could not react to C3S. Added K2SO4 appeared as K2SO4, however added Na2SO4 appeared as the form of Na2xCa3-xAl2O6, (Na0.8Ca0.1)SO4 and Na2SO4 in interstitial phase.