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 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
Preparation and Microwave Absorbing Characteristics of Ni-Zn Ferrite Composite
Journal of the Korean Ceramic Society, volume 29, issue 7, 1992, Pages 505~510
The influence of excess iron content (x) and reaction atmosphere on permittivity, permeability and microwave absorbing properties has been investigated in composite specimens embeded with (Ni0.4Zn0.6O)1-x(Fe2O3)1+x powders. A nitrogen atmosphere used for the reaction of the ferrite with excess iron composition (x>0) enhances spinel formation, and thereby increases both the magnetic and the dielectric loss of the ferrite composite. We also investigated the relation between the electromagnetic constants and the absorbing properites using impedance-matching solution maps for zero reflection. It is suggested that a superior microwave absorber can be fabricated through atmosphere and excess iron control during the powder process.
Effect of Additives of Sintering and Mechanical Properties of
Journal of the Korean Ceramic Society, volume 29, issue 7, 1992, Pages 511~516
In this study, SiC powder and Si powder were used as the raw materials. Mixture was prepared with addition of Al2O3 and Fe2O3 at 0.1~0.5wt% respectively. After this step, the mixture was pressed and nitrided for 30 hrs at 140
under NH3-N2 atmosphere. Mechanical properties of sintered specimens were investigated from measurement of porosity, bulk density and three point bending test. nitration reaction extent was observed at the change of mass before and after reaction, and the microstructure and the change of
-Si3N4 were observed by XRD and SEM. In the current work, the results are as follows 1. When Fe2O3 added, the nitridation increased with the content of Fe2O3, and the bending strength was increased from 0.1 wt% to 0.3 wt%, and decreased to 0.5 wt%. 2. When Al2O3 added, the nitridation and the bending strength increased little by little with the content of Al2O3 3. The bending strength of the specimen added with Fe2O3 were higher than that with Al2O3. Because the specimens contained Fe2O3 had much more the whisker type crystal of Si3N4 contributing to strength than contained Al2O3.
A Comparative Study of Microstructure and Fracture Behavior in Reaction-Bonded Alumina
Journal of the Korean Ceramic Society, volume 29, issue 7, 1992, Pages 517~524
For the present study two alumina bodies were prepared. The sinter-aid alumina body(SAA) was made by conventional sinter-process using sintering additives of TiO2 & MgO/CaO and the reaction-bonded alumina (RBA) made from Al-Al2O3 mixed powder. A comparison was made between those two bodies and this investigation seeks to evaluate their microstructure, physical properties and material's reliability as well as their fracture behaviour. In spite of its considerable microstructural densification accompanied by sintering shrinkage, SAA is largely inferior to RBA in fracture strength. However, SAA shows a somewhat higher m-value than RBA in respect to the material's reliability, the Weibull modulus(m). RBA, which has high fracture strength, shows much longer lifetime under static loading than SAA. Though, as with m of fracture strength, the reliability(mt) of lifetime prediction in RBA is less high than of SAA.
Preparation and Characterization of Fine
Powders by Vapor-Phase Hydrolysis of TiCl4
Journal of the Korean Ceramic Society, volume 29, issue 7, 1992, Pages 525~532
TiO2 fine powder was synthesized in the gas phase by chemical vapor deposition using hydrolysis of TiCl4. Content of rutile phase in the powder was investigated. Powder characteristics such as size, crystallinity and morphology were also studied by means of TEM, SEM and XRD. Rutile phase in TiO2 powder started to be formed from 100
and the content increased with the reaction temperature and TiCl4 concentration. As the temperature increased from 80
, the primary particle size increased while secondary particle size decreased. Spherical secondary particle with fine primary crystals agglomerated was produced at low temperature of 80
whereas the grown primary particle being final particle size was produced at higher temperature of 140
. Other effects of TiCl4 and H2O partial pressures on particle size were also reported in this study.
A Study on the Microstructural Control of LAS Ceramics (II): Influence of L
Frit Addition on the Microstructure and Thermal Expansion of
Journal of the Korean Ceramic Society, volume 29, issue 7, 1992, Pages 533~538
Effect of Li2O.4B2O frit on the microstructural and thermal expansion behaviour of
-spodumene ceramics was investigated. With 4.0~8.0 wt.% frit addition, sintering temperature range was enlarged and densification was enhanced through liquid phase sintering. As the amount of frit addition was increased, thermal expansion coefficient was increased to 1.72
-1 of its highest value, which indicated that the increment of thermal expansion coefficient due to the second phase was constrained.
Manganese Zinc Ferrite Singel Crystal Growth by Continuous Crystal Growing Method
Journal of the Korean Ceramic Society, volume 29, issue 7, 1992, Pages 539~543
The continuous growth method was developed for Mn-Zn Ferrite single crystals. It is a new process that the polycrystalline MnχZn1-χFe2O4 raw materials are supplied continuously from the powder feeding system to the crucible heated by R.F. induction and melted in the crucible, and after the single crystals seed is attached to crucible's hole, the crystals are pulled downward with rotation. Growing the crystals by using the growth method different from the conventional Bridgman or Floating Zone method, we defined the factors having effect on the crystal growing through the pre-experiments. They are temperature distribution in the crucible, melt velocity according to its height, wettability between the crucible's bottom and melt. Therefore, Mn-Zn Ferrite single crystals were to be grown by attaining the appropriate melt height in the crucible, powder feeding rate, temperature gradient between the crucible and interface, crystal growing speed, and this method was confirmed to have possibility for single crystal growing.
The Fabrication of Zirconia Fibers from Sol-Gel Process
Journal of the Korean Ceramic Society, volume 29, issue 7, 1992, Pages 544~550
Zirconia gel fibers could be made by drawing from polyester sol containing zirconyl oxychloride during the reaction between ethylen glycol and citric acid. In this case, the critical mole ratio of zirconyl oxychloride to citric acid was about 4 and by adding CaCl2 and calcining the gel fiber in the air, cubic stabilized zirconia fibers having much micropores at surface could be obtained.
Interfacial Characterization of
-Sialon Powder Prepared from Hadong Kaolin
Journal of the Korean Ceramic Society, volume 29, issue 7, 1992, Pages 551~557
X-ray diffraction patterns, IR spectra and zeta-potentials of silicon nitride and
-Sialon powders were investigated before and after surface manipulations.
-Sialon powder was produced from Hadong Kaolin by the carbothermic reduction and simulataneous nitridation. Isoelectric points of as-prepared Si3N4 and
-Sialon powders were 8.4 and 7.4, respectively. After both silicon nitride and
-Sialon powders were oxidized at 80
for 24 h in air, the isoelectric points of these powders corresponded to that of silica (pH=3). I case of the addition of Darvan C as deflocculant, its isoelectric point was 3 and zeta-potential was nearly constant in the range of pH 5~12. When SN 7347 was used as deflocculant, its isoelectric point was 8.3 and zeta-potential over -156 mV was measured above pH 11.
Effect of Crystal Phases on the Properties of Sintered Glass-Ceramics for
Journal of the Korean Ceramic Society, volume 29, issue 7, 1992, Pages 558~564
The effect of composed phase in the hot pressed CaO-MgO-Al2O3-SiO2 glass-ceramic has been investigated through microstructure studies, thermal, physical and mechanical properties. Sintering was done in the condition at the temperature range 900~95
for 20~120 mins under 7.5 MPa unilateral pressure. Sintered ceramics were composed of diopside, anorthite, residual glass and the portion of each phase was dependent on the sintering temperature and the holding time: as the temperature increases, the amount of diopside increased and then the rate of increase of diopside reduced with increasing anorthite. The thermal expansion coefficient of hot pressed was reduced with increasing crystallinity of hot pressed and was in the range of 6.69~7.46
10-6 K-1 below
. The elastic constant of hot pressed increased with increasing crystallinity up to about 80%, but after that was reduced due to the change of microstructure. The flexural strength of sintered ceramics was decreased with higher temperature and holding time, while the fracture toughness of those increased. It was shown that the physical and mechanical properties of hot pressed ceramic were related to the fraction of composed sintered ceramics, similar to a particulate composite, to the crystallinity of 80% of the glass-ceramic.
Co Gas Sensing Property of ZnO/CuO Hetero-Contact Ceramics
Journal of the Korean Ceramic Society, volume 29, issue 7, 1992, Pages 565~571
Gas sensing properties of P-N contact ceramics, composed of ZnO and CuO pairs sintered at different temperatures, were studied for 1% CO gas. Between 10
temperature range, it was observed that 2-probe current-voltage (I-V) characteristics, temperature and voltage dependence of sensivities were dependant largely upon ZnO samples. Pairs including a ZnO sample sintered at 110
showed maximum senitivity of 9 and 13 depending upon counterpart CuO samples, at 260~29
. On the other hand, pairs including a ZnO samples sintered at 90
showed increasing sensitivity within in the measured temperature range and maximum sensitivities were about 4.
Permittivity in Tetragonal and Rhombohedral Phase PZT Ceramics after Poling
Journal of the Korean Ceramic Society, volume 29, issue 7, 1992, Pages 572~576
Dielectric constant of ferroelectric ceramics with poling is important in relation to the mechanism of dielectric breakdown. From the research about the dielectric constant variation with poling in tetragonal and rhombohedral phase PZT ceramics, it is known that the dielectric constant after poling is determined by competing effects between increasing effects (compressive stress induced by electrostriction of piezoelectric effects) and decreasing increase in large grain size with poling is smaller than in small grain size.
Study on Sintering Properties of
Composite by Self-Propagating High Temperature Synthesis Method
Journal of the Korean Ceramic Society, volume 29, issue 7, 1992, Pages 577~585
TiB2 and TiC were prepared from the mixture of metal titanium, boron and graphite powders in Argon atmosphere by Self-propagating High-temperature Synthesis method. The sintered properties of TiB2-TiC composite as a function of TiC content and sintering temperature were investigated in TiB2 matrix. The sintered properties were the most excellent at 10 wt% TiC content in TiB2-TiC composite. The relative density, M.O.R strength, hardness and fracture toughness of TiB2-10 wt% TiC composite sintered at 190
for 90 min by hot-pressing under the pressure of 30 MPa were 98.6%, 634 MPa, 2128.1 kg/
and 4.09 MN/m3/2, respectively.