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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
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Study on Thermal Decomposition of Korean Diaspore
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 307~312
The investigation has been performed to study thermal dehydration of Song-sug, Pyung-il-do and Chung-mu diapore in Korea. Thermal analysis of Korean diaspore showed two steps of dehydration by dispore and kaolinite. The activation energy of dehydration reation of each diaspore was calculated by kissinger's method, and the results obtained were 63.608, 37.867 and 54.885Kcal/mol, respectively.
Influence of Testing Method on the Fracture Toughness of Cordierite-SiC Whisker Ceramic Composites
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 313~320
Fracture toughness of hot pressed cordierite-SiC whisker ceramic composites contained up to 40vol.% SiC whiskers were determined by using the indentation crack length(IC), indentation strengthin-bending(IS), and single-edge notched-beam(SENB) methods. The results were compared to stress intensity factor, KB, at the crack branching boundary measured by using the mirror zone radius (MZ) method. IS method seems to provide a more reasonable estimation of fracture toughness than other methods for these composites.
Studies on AlF3-(Mg＋Sr＋Ba)F2-P2O5 Glasses III. Chemical Durability
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 321~328
The chemical durability of six alumino fluorophosphate glass samples studied. The composition of glass varied with MgF2 content from 0 to 12.5wt% in 30AlF3-2MgF2-(50-x)MF2-10P2O5(M; Sr, Ba). Samples were maintained in distilled water at 95
from 1 to 100hrs. Weight loss, pH change and leached elements of the solution, and IR transmittance of samples were measured and also their surfaces were observed by SEM. Chemical durabilities of these samples were increased with increasing MgF2 contents. The following various properties were increased rapidly up to 10 hours after that changed slowly. The sample after leached at 95
during 100 hrs showed 0.5mg/
in weight loss. The pH of leached solution is 6.2 and concentration of Mg, Sr, and Ba element of that leached solution were 24,115 and 125 ppm, respectively. The infrared transmittance of leached sample decreased 7% compare to unleached one. And also SEM photomicrograph and EDS analysis showed that the corrosion of samples were decreased with respect to increasing MgF2 content.
Diffusion of Ion in Hardened Cement Paste Containing Slag-Siliceous Powder(II) Diffusion of SO4-- Ion
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 329~334
Diffusion of SO4-- ion in hardened cement paste with slag and siliceous powders such as silica fume and white carbon was investigated. Ca(OH)2 from hardenend cement paste was dissolved by sea-water and then gypsum was formed from the reaction of Ca++ in hardenend cement paste and SO4-- ions in MgSO4 solution. A part of the gypsum by reaction with calcium aluminate hydrates formed ettringite. Amounts of SO4-- ions passed through hardened cement paste was less than that of Cl- ions(Dcl-) in hardened cement paste were 0.1∼0.6
/sec and 1∼4
A Study on the Glass Strengthened in Salt Solution by Chemical Ion Exchange
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 335~342
There were several numbers of studies on chemically strengthening glass. Most of them were strengthened in molten salt bath below transformation range of glass. Apart from them, this study used solution hydration technique by Autoclave. After determining proper concentration of AgNO3 salt solution, experimental condition varied from 4hrs to 16hrs at relatively low temperature (180, 200, 220
). The results showed that the Soda-Lime-Silica glass could be strengthened by diffusion mechanism without influence of water above 15% salt solution. Because of Ag+ ion penetration in glass surface, yellow color appeared and decreased transmittance at visible range. Modulus of rupture was increased with the amount of exchange and brittleness was decreased.
Effects of Salts on the Formation of
-Calcium Sulfate Hemihydrated from by-Product Gypsum of Phosphoric Acid Process at Hydrothermal Condition
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 343~348
The effects of salts such as aluminum sulfate as inorganic salt(2-4%), and sodium salts of citrate, tartrate, succinate, potassium tartrate and gelatin as organic salts(0.1%) on the formation of
-calcium sulfate hemihydrate from by-product gypsum of phosphoric acid process under hydrothermal condition at 123
were investigated. Aluminum sulfate solution exhibited the catalystic effected on the crystallization of
-calcium sulfate hemihydrate of which was assumed in the prismatic form, and organic salts solution exhibited little effect on the catalystic action to the crystallization, than inorganic salts. In the acidic solution with sulfuric acid(pH=2), needle like crystal of calcium sulfate hemihydrate was obtained. Hydrothermal process with aluminum sulfate solution also showed certain amounts of impurity removal such as phosphorus penataoxide from calcium sulfate hemihydrate.
Thermomechanical Properties of
-Sialon Synthesized from Kaolin
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 349~356
-Sialon powder was synthesized by the simultaneous reduction and nitridation of Hadong kaolin at 1350
in N2-H2 atmosphere, using graphite as a reducing agent. The synthesized
-Sialon powder was pressurelessly sintered over 1450-1850
in nitrogen atmosphere. The average particle size of
-Sialon powder was about 4.5
. The relative density, M.O.R., fracture toughness and micro-hardness of
-Sialon ceramics sintered at 1800
for 1 hour were 92%, 36 kpsi, 2.8MN/㎥/2 and 13.3 GN/㎡, respectively. The critical temperature difference (ΔT) in water quench thermal shock behavior showed about 375
for the synthesized
Forsterite 소지에서 Zirconia 거동에 관한 연구
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 357~363
This study consists of two powder preparation process. One is that the synthesized Forsterite at 1400
mixed with Zirconia powder. Another, theoretical Forsterite composition mixed with Zirconia. These two Forsterite bodies were heat-treated at 1400
. Synthesized Foresterite composition showed higher density, strength than Forsterite composite which was directly mixed with Zirconia KIC value was measured by Microhardness Indentation method. It shows the highest value when 15 weight percent Zirconia dispersed.
Effect of Crystallization of Matrix Phase on the Fracture Toughness of Silicon Nitride Ceramics
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 364~368
The Si5AION7 specimens containing 20% YAG composition have been sintered and then heat treated to induce the crystallization of the matrix glassy phase. Crystallization of YAG phase during the heat treatment was detected from the X-ray diffraction patterns and the consequent changes in room temperature toughness as well as in microstructures were investigated. Almost all the glassy boundary phase were found to crystallize even after 5 minutes of heat treatment and the KC at room temperature decreased accordingly. The results show that the matrix crystallization can be induced by slow cooling from the sintering temperature.
Influence of Dopant Al2O3 and Surface Roughness on the photoelectrochemical Conversion of TiO2 Ceramic Electrodes
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 369~375
The effects of dopant Al2O3 and surface roughness on the photoelectrochemical conversion of TiO2 ceramic electrodes were investigated. The photocurrent increased with increasing the amount of dopant Al2O3 up to 0.1wt% and 0.05wt% in the specimens reduced at 700
, respectively, and then decreased. However, the photoresponse appeared around 415 nm, which very closely corresponds to the energy band gap of TiO2(∼3.0eV), regardless of reduction temperature and the amount of Al2O3. And the photocurrent increased with increasing surface roughness in the undoped TiO2 ceramic electrode.
Mullitization of HF-treated Kaolin
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 376~384
Kaolin was treated by HF and fired at high temperature in order to reduce silica and impurity minerals of kaolin, and eventually to increase the yield of mullite. The kaolin structure was destroyed by HF-treatment and transformed into mullite at lower temperature than those of non-treated kaolin. Not only the silica content of kaolin was reduced, but also the crystalline structure of it was destroyed by HF-treatment.
Early Hydration of Tricalcium Silicate(III)
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 385~391
Zeta potential according to the hydration time was studied during the early hydration of C3S with and without CO2 atmosphere. Zeta potential was low as a level of 20mV at the first and second exothermic peaks of heat evolution, but it was rapidly increased up to a level of 300mV. In the CO2 atmosphere, zeta potential was level of 60mV at 10 minutes hydration and it's value became a low gradually according to the hydration time. Zeta potential was also proportioned to the Ca2+ concentration in the liquid phase, i.e., there was positive correlation between zeta potential and Ca2+ concentration. The existence of silicate layer was not found out on the hydrated C3S in the CO2 atmosphere by SEM-EDAX.
Dielectric Breakdown and Electric Stress Distribution in Ferroelectrics
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 392~396
Pure barium titanate was sintered at
for 2, 4, 8, 16 hr to control their grain size. The measurements of breakdown strength and partial discharge characteristics were performed under rising AC voltage(60Hz). With increase of sintering time, the average grain size was increased and breakdown strength was slightly decreased. Partial discharge in pores was observed under high voltage, and a model of dielectric break down in barium titanate ceramics is proposed.
Hydrothermal Precipitation of PZT Powder
Journal of the Korean Ceramic Society, volume 24, issue 4, 1987, Pages 397~403
Pb(Zr0.52Ti0.48)O3 powders were prepared by hydrothermal synthesis. Using soluble salts such as Pb(NO3)2, TiCl4 and ZrOCl2
8H2O and oxide such as PbO and TiO2 as starting materials, PZT powder was hydrothermally synthesized at the temperature range between 150
. The result showed that reactivity by alkali was decreased in the sequence of Pb(NO3)2, TiCl4, ZrOCl2, PbO, TiO2 and ZrO2. Using the first three soluble salts, PZT powder was synthesiged at 150
for 1hr. In PbO-TiCl4-ZrOCl2 system, PZT powder was synthesized at 150
for 8rs. In Pb(NO3)2-TiO2-ZrOCl2 system, PZT powder was synthesized at 150
for 16hrs, in PbO-TiO2-ZrOCl2 system, the powder was synthesized at 200