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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Ceramic Society
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Journal DOI :
The Korean Ceramic Society
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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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The Crystallographic Properties of TiC Deposited on Different Substrate Steel by Chemical VaporDeposition
Journal of the Korean Ceramic Society, volume 24, issue 6, 1987, Pages 519~526
TiC was deposited onto several substrate steels by the Chemical Vapor Deposition technique from TiCl4-CH4-H2 gas mixtures in the horizontal resistance furnace. Deposition rates and morphologies of the coatings were investigated with the carbon contents. Deposition thickness increased linearly with the deposition time in the Presence of CH4 gas. The various interlayers of coating by EDS and X-ray Diffraction were proved as Cr7C3 and Fe3C. Chromium contents did not affect the preferred orientation of TiC deposit. The deposition was controlled by a mass transport and a surface reaction in case of 1 wt% C-5.25 wt% Cr steel irrespective of deposition temperature.
Electro Optic Characteristics of PLZT Ceramics Fabricated by Two Stage Sintering Method
Journal of the Korean Ceramic Society, volume 24, issue 6, 1987, Pages 527~536
PLZT ceramics of composition La/Zr/Ti=X/65/35(X=5-10 at.%) were fabricated by two state sintering technique.Transparent PLZT ceramics were obtained in the composition above 8 at. % La. Variations of electrooptic properties in the compositions between 8 at. % and 9 at. % La were able to be expected from the significant differences of P-E hysteresis curve and the changes of dielectric phase transition. The range of birefringence of 8/65/35 specimen was 4.08
10-3. Domain switching of 9/65/35 specimen was agreed with the applied electric pulse because input pulse signal corresponds to optical pulse response.
The Microstructure and Electrical Properties in the Pb(Sb1/2 Nb1/2)O3-PbTiO3-PbZrO3 System with MnO2 Addition
Journal of the Korean Ceramic Society, volume 24, issue 6, 1987, Pages 537~542
The microstructure and electrical properties of Pb[(Sb1/2 Nb1/2)0.08 Zr0.49 Ti0.48]O3 with MnO2 addition have been investigated in this work. The amount of MnO2 addition was 0, 0.4, 0.8, 1.2, 2.0 wt%, respectively. The soild solution range of MnO2 that assumed in this composition according to thevariations of micro-structure and electrical properties was 0.4-0.8 wt%.
The Effects of Deposition Variables on the Chemical Vapor Deposition of SnO2
Journal of the Korean Ceramic Society, volume 24, issue 6, 1987, Pages 543~552
The effects of deposition variables on SnO2 CVD were investigated for SnCl4＋O2 reaction at 300∼700
10-3 atm, and Po2=5
10-4∼1 atm. A thermodynamic equilibrium study on Sn-Cl-O system has been performed with the computer calculation. The calculation indicates that major species participating the reaction in SnCl4 and not intermediate species, SnCl2. Good uniformity of the film thickness was obtained at the flow rate of 11cm/sec, which resulted from the stable gas flow in our cold wall reactor. The experimental results showed that apparent activation energy of the deposition was about 13.5Kcal/mole below the temperature of 500
and the deposition mechanism was controlled by surface reation. The behavior of deposition rate on the reactant partial pressures could be explained with the Langmuri-Hinshelwood mechanism. X-ray study demonstrated that SnO2 film deposited at temperatures above 400
were polycrystalline with tetragonal rutile structure and grew with (211) and (301) preferred orientations.
Characteristics of BaFe12O19 Particles Extracted from Amorphous Ba-Ferrite
Journal of the Korean Ceramic Society, volume 24, issue 6, 1987, Pages 553~560
Amorphous ferrites with composition B2O3-mBaO-nFe2O3 were prepared by an ultra rapidquenching technique. X-ray patterns and SEM reveal the products to be amrophous at room temperature. BaFe12O19 fine particles extracted from amorphous Ba-ferrites which additived Al2O3, SiO2, TiO2 and CoO have narrow size distribution, average 0.2
, and coercive force, average 1400 Oe, increased with increasing TiO2 amounts. The obtained BeFe12O19 fine particles would be appreciated as perpendicular magnetic recording media.
The Effects on Alkoxy Group and Catalyst in Hydrolysis of Silicon Alkoxide System
Journal of the Korean Ceramic Society, volume 24, issue 6, 1987, Pages 561~571
In case of glass ceramics and powder preparation from the metalakoxide solutions, metalakoxide solutions with a various species of alkoxy groups have unique characteristics. Therefore, in this study, the mixing ability of homogeneous sol, gel morphology and physical properties of gels were investigated by the changes in terms of the different four alkoxy groups, CH3-, C2H5-, i-C3H7-n-C4H9-, along with the catalyst for the purpose of the observation about the homogenous transition range from sol to gel. As a result, when the fixed condition was mol ratio of H2O/Si(OR)4=2.0 and variables were batch composition and addition amount of catalyst, the characteristics of Tetra-normal-Butoxysilane and Tetra-iso-propoxysilane systems had very narrow sol-gel conversion region than Tetramethoxysilane and Tetraethoxysilane system. And silicon-alkoxide, systems having narrow sol-gel conversion region were enlarged by addition of catalyst. In viewpoint of the weight loss of gel produced by hydrolysis of silicon alkoxide systems with different four alkoxy groups, the amounts of weight loss of gel containing large molecular alkoxy groups were much more than those of small molecular alkoxy group.
Humidity Dependence of Electrical Conductivity of Vacuum Evaporated Au Films on Glass
Journal of the Korean Ceramic Society, volume 24, issue 6, 1987, Pages 572~578
The vacuum evaporated Au films on soda-lime glasses were measured by the electrical conductivity with the variation of the annealing time, relative humidity, and temperature. Au films structures were observed by scanning Electron Microscope and X-ray Diffractometer. As the annealing time and temperature increased, the electrical conductivity was increased due to the migration or annihilation of defects, but the electrical conductivity was decreased as with the relative humidity increased. Au films by XRD and SEM examination showed the negligible effect of chemical reactions.
PTCR Effects In Nb2O5 Doped BaTiO3 Ceramics Prepared By Molten Salt Synthesis Method
Journal of the Korean Ceramic Society, volume 24, issue 6, 1987, Pages 579~585
The effects of flux KCl and dopant Nb2O5 on the PTCR characteristics of BaTiO3 prepared by molten salt synthesis method have been investigated. As the amount of dopant Nb2O5 is over the solubility limit in BaTiO3, the room-temperature resistivity increases, and the PTCR effect and the grain size decrease. The variation of the amount of flux KCl slightly influences on the room-temperature resistivity, PTCR effect and grain size in Nb2O5 doped BaTiO3, but BaTiO3 ceramics prepared by the method of molten salt synthesis show larger PTCR effect than those of conventional calcining of mixed oxides.
Role of the Strain Energy in Diffuse Phase Transition of (Pb, Ba)(Zr, Ti)O3
Journal of the Korean Ceramic Society, volume 24, issue 6, 1987, Pages 586~592
The role of the strain energy and phase stability in the diffuse phase transition have been investigated in the highly disordered solid solution, (Pb1-xBax)(Zr0.4Ti0.6)O3 (0.2 x 0.4). X-ray diffraction analysis indicates that tetragonality (c/a) decreases with the increasing Ba content. Also as the Ba content increases, phase transition becomes more diffuse and at the same time dielectric relaxation as a function of measured frequencies in the 1KHz-10MHz range occurs very pronouncedly. In the Ba content range, 0.2 x 0.35, hysteresis loops are routinely observed and the loop is observed to narrow shape as the Ba content increases but becomes very slim at 40mol% Ba content. Moreover thermal analysis shows that there is no abrupt change in the thermal expansion coefficient below the apparent transition temperature at which dielectric constant becomes maximum. From the above results, it has been concluded that creation of the strain energy due to the distorthion that occurred during the phase transition suppresses diffuse phase transition.
Preparation of Al2O3-ZrO2 Composite Powders by the Use of Emulsions: I. Thermodynamic Model of the Emulsion Stability
Journal of the Korean Ceramic Society, volume 24, issue 6, 1987, Pages 593~601
A thermodynamic model to predict the stability of the water-in-oil type emulsion and the size of the droplets in stable emulsions was developed. Using this model, the effects of various factors government the droplet size in the metal salt solution-kerosene-span 80 system for the preparation of Al2O3-ZrO2 composite powders were investigated. It was shown that the given emulsion systems were thermodynamically unstable in every case but could be kinetically meta stable. When radius ofthe droplet was below nm, the increase in entropy change due to the configurational contribution of small droplets dominated the total free energy change for emulsification. The optimum conditions under which smaller deoplet was obtained were proposed and the validity of the model was proved with diameters of the droplet and composite powders experimentally determined.
Fabrication of Y1Ba2Cu3Ox Superconductor by Hot-pressing
Journal of the Korean Ceramic Society, volume 24, issue 6, 1987, Pages 602~604
The high TcY1Ba2Cu3Ox superconductor has recently gained widespread interest in the scientific community. The principal problems at the present time are how to densify this material and how to raise the critical current density. To date the majority of samples have had densities of 90%(of theoretical) or less. In this study we report that we obtained density of 96% by Hot-Pressing method.