Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
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
Thermal Expansion Behavior of Cordierite-SiC Whisker Ceramic Composites
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 411~416
Thermal expansions and thermal expansion coefficients of cordierite ceramics reinforced by SiC whiskers up to 40 vol. % were investigated. The composite specimens were hot pressed at 1523K for 30 min under 28.5 MPa pressing pressure in Ar atmosphere. Thermal expansions of the hot pressed composites were measured using a differential dilatometer up to 1262 K in air. Thermal expansions and thermal expansion coefficient of the composites increased with SiC whisker content. Thermal expansion behaviors of the composites were well explained by modelling parallel slabs randomly distributed on the whisker plane as the microstructural element of the composites.
Kinetics of the Thermal Decomposition of Mg-Al Sulfate Hydrate
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 417~422
Kinetic studies were made on the thermal decomposition of hydrated magnesium aluminum double sulfate by a nonisothermal TG method. Thermal analyses of the dehydration of tricosahydrate showed that the reaction proceeded via decahydrate to the anhydrous MgAl2(SO4)4 in the range 50
. Decomposition of MgAl2(SO4)4 occurred as the two-step between 650
. Dehydration of MgAl2(SO4)4
23H2O and a 2D diffusion controlled with an activation energy of 16.6kcal/mole, respectively. MgAl2(SO4)4 fitted the contracting volume model with an activation energy of 10.5kcal/mole, and MgSO4 fitted a contracting area model with an activation of 4.5kcal/mole.
Effect of Calcination Temperature on Al2O3-ZrO2 Ceramic Prepared by Sol-Gel Process
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 423~430
Characteristics of Al2O3-ZrO2 powders prepared by sol-gel process and their sintering behavior were investigated as a function of calcination temperature. The sol-gel processed powders were calcined at 800, 900, 1000, 1100, 1200
, and analyzed by X-ray diffraction technique. Pore size and distribution of green compact of the calcined powders were measured by mercury porosimeter. It is suggested that the optimal temperature of calcination for the sintering of Al2O3-ZrO2 powder prepared by sol-gel process is 1100
. In the Al2O3-17vol.% ZrO2 sintered specimen, which was sintered at 1600
for 2hrs in air, 69vol.% tetragonal phse existed.
Fabrication and Characterization of High Purity Al2O3 by Decomposition of Selicite
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 431~436
High purity Al2O3 has been extracted from serlcite of clayminerals, selicite was treated by H2SO4(2N∼18N) solution, NH4OH treatment(PH8.5∼10.0) and metallic impurities such as Fe were removed by NaOH treatment. The tendency of extraction yield of
-Al2O3 have been investigated by relating reaction time, acid concentration. Reaction products were analyzed by DT-TGA, chemical analysis and X-ray diffractometer. Prepared
-Al2O3 power is fired in air at 1400
2hr. The results are as follows; 1. The most suitable extracting conditions of
-Al2O3 from Selicite were N-H2SO4, 120 min acidtreating time. 2. The optimum pH condition was 9.0. 3. Physical properties of sintered Al2O3 bodies were as follows. Relative density is 99%. Water absorption is 0.26%. Rock well hardness is 89.
Development of White Carbon, Silica Gel and Aluminum Sulfate from Clay Minerals
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 437~446
In this study the attempts were made to investigate the possibilities of using domestic clay minerals and zeolite, which are available in almost unlimitted quantities, for preparation of aluminum sulfate, white carbon and silica gel. Aluminum sulfate was obtained by the method of sulfuric acid treatment. White carbon and silica gel were prepared by utilizing crystalline silica which was obtained as a by product during preparing the aluminum sulfate. White carbon was obtained by reacting 5.0 weight percent sulfuric acid solution with water glass which was a reaction product of crystalline silica and soldium hydroxide in a autoclave, while silica gel was obtained by reaction 10.0 weight percent acetic acid solution with water glass.
Effect of Seeding on Preparation of
-Al2O3 Powders by Boehmite Sol-Gel Process
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 447~452
-Al2O3 powder was produced at 1000
by the boehmite sol-gel process with seeding 2 wt%
-Al2O3. The processes and mechanisms of fornation of
-Al2O3 was investigated using DTA/TG, XRD, TR spectroscopy and thermodynamic analysis. The specific surface area of the obtained
-Al2O3 was 16.3㎡/g.
Thermal Decomposition of
$-Sialon by Graphite
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 453~460
β'-sialon(Z=2.7) specimens with <30%wt. graphite as a reducing agent were decomposed at 1350°up to 1,450℃ under the atmosphere of 90% N2-10%H2. The decomposition of β'-sialon was calculated from the change in Z-value, and the formation of new minerals was identified from X-ray diffraction patterns. The decomposition reactions of sialon were considered to yield a stable sialon close to β-silicon nitride and some aluminum compounds according to the following equations; β'-sialon(s)＋C(s)＋N2(g)→β2-sialon(metastable)＋β3-sialon(stalbe phase) β2-sialon(s)＋C(s)＋N2(g)→β3-sialon(s)＋AlN(s)＋α-Al2O3(s)＋15R(s)＋SiO(g)＋Al2O(g)＋CO(g) Z-value; β2( 3.5)>β'( 2.7)>β3( 0.5) The decomposition rate of sialon was controlled by two mechanisms ; One was characterized by the interface area of contact, corresponding to an apparent activation energy of 50.5Kcal/mol in the initial stage, and the other by the diffusion, corresponding to that of 104.3Kcal/mol in the final stage of the decomposition.
Crystal Growth of Mn-Zn Ferrite form High-Temperature Solutions
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 461~469
Single crystals of Mn-Zn Ferrite were grown by slow cooling method using Na2B4O7 as flux agent. The effects of flux content and cooling rate on the types of crystals, and the relation between supersaturation and growth mechanism were studied. As a result, the types of grown crystals occurred as plate, hopper and octahedral crystals. The occurrence of these crystal types was dependent on flux content. The habit was found to correlate with the growth rate and supersaturation. The lateral growth of a dendritic crystal is related to the twin layer. The growth of crystals from borax melts mainly occurred by the layer-spreading growth following corner and edge nucleation caused by high supersaturation in the melt. Especially, the plate crystals were produced on top of the melts. The hopper and octahedral crystals occurred at lower supersaturation than the plate crystals.
Effects of KP, QM on Filter Characteristics of Pb(Mg1/3N2/3)O3-PbTiO3-PbZrO3 Ceramics
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 470~476
The system of 0.1Pb(Mg1/3N2/3)O3-yPbTiO3-zPbZrO3 piezoelectric ceramics was made in the radial model disk and ring dot type filter. The resonant frequency(fr) variations were investigated for 100 hours and the temperature range from 20
. As the results, the morphotropic phase boundary was supposed to be the composition of 45 y 50 and 40 z 45. The best characteristic of againg effect, after 10-hours, was composed of y, z=45. The stabilized characteristic of temperature varition, to become 0.1% up to 100
, was composed of y=50 and z=40. The bandwidth was broadened with increasing the electromechanical coefficient(kp), and the filter characteristics was approached ideal mode with increasing mechanical quality factor(Qm). Kp and Qm affected combinationally on filter characteristics.
Aging Behavior and Electric Field Induced-Domain Stabilization in Cr2O3 Doped Pb(Zr0.525 Ti0.475)O3 System
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 477~483
Cr2O3 doped Pb(Zr0.525 Ti0.475)O3 piezoelectric ceramics were prepared from reagent grade oxide mixture, PbO, ZrO2, TiO2 and Cr2O3. Piezoelectric and aging properties of specimens were measured for various additions of Cr2O3. Generally, it has been known that aging rate decreased with Cr2O3 addition by stabilizing the domain wall. But hysteresis loops showed that the domain destabilization was occurred at high electric field (larger than 10KV/cm). In smaller additions of Cr2O3 (0-0.2mol%), aging rate increased and microcracks were created with increasing poling filed due to increasing internal stress. In larger additions of Cr2O3(0.4∼0.6mol%), aging rate decreased with increasing poling field.
A Study on Solid Reaction of BaCO3-TiO2 System
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 484~490
Diffusion coupling experiment was done to study expansion of body and soild reaction in BaCO3-TiO2 system. Specimen of BaCO3 and TiO2 was formed with Pt-mark's method. Each specimen was fired at interval of 25℃ from 900℃ to 1000℃ for 2hrs. After that, specimen was fixed with resin and polished. Product layers of specimen were observed with SEM and EDS. The result were following; 1. Diffusion component is Ba2+, which diffuse toward TiO2. 2. Large crack between layer of BaCO3 and Ba2TiO4 was generated because of difference of thermal expansion coefficient. 3. Ba2TiO4 is formed to TiO2 body by the reaction of BaTiO3 and BaO and its structure is very porous. 4. BaTiO3 changes immediately to Ba2TiO4 by the reaction of BaO. But BaTiO3 which formed by the reaction of TiO2 and Ba2TiO4 exsists as layer because the diffusion distance of Ba2+ is far.
-Sialon from Kimcheon Quartzite
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 491~499
Silicon nitride powder synthesized from Kimcheon quartzite and commercial reagents, AlN and Y2O3 powders were used to prepare the partially and fully stabilized Y-
-Sialon ceramics by the pressureless sintering at 1800
for 2 hours in N2 atmosphere. Good mechanical properties of the prepared Y-
-Sialon ceramics were found over 0.4∼0.6 of the Yttrium solubility range, X, in the equation Yx(Si12-4.5x, Al4.5x)(O1.5x, N16-1.5x). The properties of these prepared Y-
-Sialon ceramics were compared with those prepared in the same way from a commercial Toshiba Si3N4 powder.
Synthesis of Monodispersed Silica Fine Particle by Hydrolysis of Ethyl Silicate(1)
Journal of the Korean Ceramic Society, volume 24, issue 5, 1987, Pages 500~506
In order to synthesize monodispersed spherical silica fine particles, we investigated the reaction of hydrolysis of 0.05∼4.0 mole Si(OC2H5)4-0.01∼7.60mole NH3 -0.24∼38.40 mole H2O-2.62∼16.88mole C2H5OH systems. The range of the composition of solution which spherical silica particles were formed was enlarged according to an increase in concentration of Si(OC2H5)4. Larger particles were obtained at higher molar ratios of Si(OC2H5)4/C2H5OH, NH3/H2O and H2O/Si(OC2H5)4 and at a lower reaction temperature.