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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 29, Issue 12 - Dec 1992
Volume 29, Issue 11 - Nov 1992
Volume 29, Issue 10 - Oct 1992
Volume 29, Issue 9 - Sep 1992
Volume 29, Issue 8 - Aug 1992
Volume 29, Issue 7 - Jul 1992
Volume 29, Issue 6 - Jun 1992
Volume 29, Issue 5 - May 1992
Volume 29, Issue 4 - Apr 1992
Volume 29, Issue 3 - Mar 1992
Volume 29, Issue 2 - Feb 1992
Volume 29, Issue 1 - Jan 1992
Selecting the target year
Characterization of SiC-SiC Whisker Matrix Retaining Electrolyte in Phosphoric Acid Fuel Cell
Journal of the Korean Ceramic Society, volume 29, issue 8, 1992, Pages 587~592
Sheets of SiC-SiC whisker maxed matrix were prepared from the mixed slurry of SiC whisker and SiC matrix by the rolling method. With the increase of SiC whisker, the pore size, the porosity and the phosphoric acid absorbency of the matrix were increased, while the bubble pressure was decreased. The activation energy for the transfer of H+ ion was decreased with the increase of mixing ratio of SiC whisker to the SiC matrix from the measurement of hydrogen ion conductivity. The activation energy was evaluated as 0.25 eV when the mixing ratio of SiC whisker to the SiC matrix was 1 : 2 and the activation energy was 0.16 eV for the 2 : 1 matrix. It means that SiC whisker matrix contributes to attain a better microstructure for the diffusion of hydrogen ion. From the measurement of single cell performance of matrix with various mixing ratio, it is concluded that if SiC-SiC whisker maxed matrix has a sufficient bubble pressure to prevent the crossover of H2 gas, the current density of a fuel cell is increased with the increase of acid absorbency of the matrix. Current density was improved from 140 mA/
for 0.25 mm thickness of matrix to 170 mA/
for the 0.20 mm one at 700 mV.
The Properties of ORMOSIL with Adding Organic Silane in TEOS System(I)
Journal of the Korean Ceramic Society, volume 29, issue 8, 1992, Pages 593~600
Through sol-gel processing, Inorganic-organic composite was obtained. The influence of water content used in hydrolysis on the bonding state, microstructure, strength, and elongation into IR, NMR, Tg, etc. As the water content was increased, the bonds between inorganic Si-(OH) and organic Si-(OH) increased, and relatively denser microstructure was formed. Tensile strength and elongation decreased with amount of water content.
Fabrication and Characterization of Carbon Fiber Reinforced
Journal of the Korean Ceramic Society, volume 29, issue 8, 1992, Pages 601~608
We investigated the influence of several processes, including the preparation of slurry and preform and the heat-treatment of the preform, on the properties of composites to fabricate the carbon-fiber reinforced glass composites having good mechanical properties. Cerander was determined to be the best binder among Cerander, Rhoplex and Elvacite 2045 by the dipping test and the binder within a preform could be completely eliminatd by burning out the specimen under 10-6 Torr at 400
for more than 1h. The fracture behavior of a composite was largely dependent on the uniformity of carbon-fiber distribution within the composite and the heat-treatment condition of the composite. The higher the glass content, the more difficult to obtain uniform distribution of carbon-fiber. As the hot-pressing temperature increased, the densification process of the composite and the formation of pore due to oxidation of carbon fiber occurred competitively. But, above 1000
the latter played a predominant role. We could fabricated the densest 15 vol.% carbon-fiber-content glass composite having the highest toughness and flexural strength of 250 MPa by hot-pressing under 15 MPa at 900
for 30 min.
Effect of the Addition of Aluminium Distearate on Manufacturing of
Journal of the Korean Ceramic Society, volume 29, issue 8, 1992, Pages 609~616
This study has been investigated on the milling of Aluminium Distearate (ADS) powder and characteristics of the ADS-doped UO2 pellets. As-received ADS powder of the agglomerated particles has not shown any milling effect because of heat generated during planetary milling. But the use of coolant to effectively remove heat generated during milling has been found an effective way in breaking up the agglomerates of ADS powder. The green density of the UO2 pellet decreases with the amount of ADS powder doped. Therefore, in order to get the sintered density of 95% pellet decreases with the amount of ADS powder doped. Therefore, in order to get the sintered density of 95% theoretical density, the 200 ppm ADS-doped UO2 pellet has to be pressed under higher compacting pressure of 3500~4000 kgf/
compared with the ADS-undoped UO2 pellet pressed under around 3000 kgf/
. The ADS-dpoed UO2 pellet with even relatively low sintered density of 10.27 g/㎤ exhibits open porosity of 1% while open porosity of the ADS-undoped UO2 pellet is reduced to around 1% only after its sintered density increases to 10.43g/㎤. It is, therefore, concluded that doping of ADS powder significantly contributes to the decrease in open porosity of the UO2 pellet. The dilatometry of the ADS doped UO2 pellet shows the sintering rate curve with the bimodal mode, which could be attributed to a phase reaction between UO2 and ADS. The X-ray diffraction analysis indicates that there occurs not any new phase formed but the shift of the peaks. It would be expected that a phase reaction resulting in solid solution would happen in the temperature range of 130
between UO2 and ADS.
Microstructural Characterization of MDF Cement-SiC Whisker Composites
Journal of the Korean Ceramic Society, volume 29, issue 8, 1992, Pages 617~622
In order to study on the effect of SiC whisker in flexural strength characterization of macro defect-free (MDF) cement composites, which composed of high alumina cement and polyvinyl alcohol, microstructural characterization of the composite specimens fabricated by the addition of SiC whiskers was investigated. Microproes are created around the SiC whisker, MDF cement didn't react with the SiC whisker. However, flexural strength of the composites have been improved. Fracture morphology of the composites, presents mainly intergranular type fracture passing around the unhydrated particles and siC whiskers, and partially transgranular type fracture. The main strengthening mechanisms of the MDF cement composites reinforced with SiC whiskers are characterized by crack deflection, microcracking, and bridging of cracks.
Effect of Modifiers in Bioglass on the Glass Properties and the Formation of Apatite
Journal of the Korean Ceramic Society, volume 29, issue 8, 1992, Pages 623~629
The possible use of bioglass as implant materials is due to its biocompatibility to human body. Even if many animal studies for the bioglasses have been performed, their compositional dependences of structures and physical properties are not fully understood. In the present work, physical property measurements such as density and thermal expansion coefficient were carried out for the bioglasses, with substitution of CaO for Na2O in bioglass composition (46.1%SiO2, 24.4%Na2O, 26.9%CaO, 2.6%P2O5:mol%). Hydroxyapatite formation on the glass surface was also examined after reacted in Tris-buffer solution. As CaO was substituted for Na2O, the bond strength between nonbridging oxygen and modifier became stronger to make glass structure rigid, and resulted in increase in density and decrease in thermal expansion coefficient. When the bioglasses were reacted in Tris-buffer solution, hydroxyapatite was formed on the bioglass surface for all prepared glasses in 2 hours, independently on CaO content, and the thickness of hydroxyapatite layer was decreased a little, while the thickness of SiO2 rich layer was decreased sharply with CaO content.
Alloying on Low Temperature Degradation of 3 mol% Y-TZP
Journal of the Korean Ceramic Society, volume 29, issue 8, 1992, Pages 630~638
Ta2O5 alloying into 3 mol% Y2O3-stabilized tetragonal ZrO2 polycrystals (3Y-TZP) increased the degradation during aging at 265℃ and the fracture toughness; both are determined by the amount of transformed m-ZrO2. It was proposed that the mechanism underlying the t→m transformation when aged at low temperatures is attributed to the reorientation of (Zzr'V ). complexes parallel to  lattice direction, which is accompanied by a relaxation of TZP lattice during annealing at low temperature. A small strain which results from the reorientation gives rise to a localized mechanical instability, thus lowering the nucleation barrier so that the t→m phase transformation (degradation) proceeds. The amount of transformed m-ZrO2 during aging becomes greater as the chemical free energy change related to the transformation, ΔGo, increases with increasing the Ta2O5 alloying content.
Effect of Additives on Electromagnetic Properties in EMI Noise Filters for High Frequency Region
Journal of the Korean Ceramic Society, volume 29, issue 8, 1992, Pages 639~645
Effects of additives on electromagnetic properties of a Ni-Cu-Zn ferrite for a noise filter in high frequency regions were studied. Both resistivity and permeability were increased with the amount of Mn2O3 up to 1wt%, then decreased with further addition. Addition of Co2O3 decreased the permeability of the ferrite and shifted the resonance frequency to a higher frequency region, which was thought due to the stabilization of domain walls. Therefore it was possible to improve both the permeability and the loss and to control the cut-off frequency by the concurrent addition of Mn2O3 and Co2O3.
A Study on the Microstructural Control of LAS Ceramics (III) : Influence of Li2O.4B2O3 Frit Addition on the Microstructure and Thermal Expansion of
-Spodumene made from Kaolinite
Journal of the Korean Ceramic Society, volume 29, issue 8, 1992, Pages 646~650
Effect of Li2O.4B2O3 frit addition on microstructural and thermal expansion behaviour of the
-spodumene ceramics made from kaolinite was investigated. With 2.0~4.0 wt% frit addition, the densification by liquid phase sintering caused low water absorption below 3% and enhancement of beding strength. As the amount of frit addition was increased, thermal expansion coefficient was increased to large scale, but in 2 wt% frit addition, its thermal expansion coefficient was constrained to 1.92
Fracture Toughness Testing in Alumina
Journal of the Korean Ceramic Society, volume 29, issue 8, 1992, Pages 651~659
Fracture toughness of alumina was determined by IF, IS, DT, SEPB methods, and the data were inter-compared. Round robin test on IF and IS methods was also conducted under the participitation of 4∼5 domestic institutes. Fracture toughness data determined by IF, IS, DT methods were similar, while those by SEPB method were smaller. Variation of toughness data determined by IS method using 98N of indentation load was significantly small compared to those determined by any other methods. Round robin test results showed that toughness data determined by IF method at various institutes do not coincide each other, while those by IS method do well coincide. Thus, it was concluded that inter-confidence on fracture toughness data, if determined by IS method at all institute, can be established between institutes.
Hydrothermal Reaction Characteristics on the ALC of Pitchstone-Lime System
Journal of the Korean Ceramic Society, volume 29, issue 8, 1992, Pages 660~666
Pitchstone reacted with CaO in hot water(9
) and increased its sedimentary volume by forming Ca(OH)2 and calcium silicate hydrates. ALC was prepared from gel at 9
and subsequently autoclaved at 18
by using the property of swelling and the physical properties of ALC was investigated with experimental conditions. When the ratio of pitchstone/CaO was 2 (CaO/SiO2 mol ratio=0.81), bulk density, modulus of rupture and thermal conductivity of the ALC were 0.75g/㎤, 73kg/
, respectively. The crystalline phase of it was mainly tobermorite. Therefore ALC was turned out to be much lightweighted and good thermal insulation.
Preparation and Characteristics of Ceramic Composite Powders Coated with
: (III) Composite Powders of
Journal of the Korean Ceramic Society, volume 29, issue 8, 1992, Pages 667~673
The alumina-zirconia composite powders of core particle ZrO2 coated with Al2O3 were prepared by the hydrolysis-deposition of the mixed aluminum salt solution of Al2(SO4)3-Al(NO3)3-Urea. The effects of hydrolysis reaction and coating parameters on characteristics of coated powders and composites were also investigated. The degree of coating could be estimated from the ratio of tetra-/mono-ZrO2 present at the room temperature after heat-treating coated powders at 120
and the result of TEM observations. When the content of ZrO2 in the dispersed coating system, the coating time, and the volume ratio of water/solution were 50 mg/g, 180 min, and 5, respectively the coating efficiency was maximum (the ratio of tetra-/mono-ZrO2 was 87/13). The relative densities of coated Al2O3-ZrO2 composites sintered at 1
for 4 hrs were about 91~98% and the maximum ratio of tetra-/mono-ZrO2 in Al2O3-20wt% ZrO2 composites was 62/38.