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 30, Issue 12 - Dec 1993
Volume 30, Issue 11 - Nov 1993
Volume 30, Issue 10 - Oct 1993
Volume 30, Issue 9 - Sep 1993
Volume 30, Issue 8 - Aug 1993
Volume 30, Issue 7 - Jul 1993
Volume 30, Issue 6 - Jun 1993
Volume 30, Issue 5 - May 1993
Volume 30, Issue 4 - Apr 1993
Volume 30, Issue 3 - Mar 1993
Volume 30, Issue 2 - Feb 1993
Volume 30, Issue 1 - Jan 1993
Selecting the target year
Preparation and Properties of Na-Ca-Si-O-N System Oxynitride Glasses
Journal of the Korean Ceramic Society, volume 30, issue 2, 1993, Pages 85~92
Oxynitride glasses in Na-Ca-Si-O-N system were prepared by melting at 135
for 2 hours in N2 gas. The effects of Si/Na mole ratio and the various Si3N4 contents were investigated. Stable oxynitride glasses can be obtained up to 9wt.% Si3N4 content in case the Si/Na mole ratio was 2.12 and 1.62, but
-Si3N4 was precipitated at 9wt.% Si3N4 content in case the Si/Na mole rtio was 1.12. Density (p), chemical durability, hardness (Hv), and fracture toughness (KIC) increased with increasing Si3N4 content. In cae the Si/Na mole ratio was 1.12, the increment of properties was remarkable but hardness and fracture toughness did not increase no longer owing to precipitation of
The Effect of MgO Addition on Mullite
Journal of the Korean Ceramic Society, volume 30, issue 2, 1993, Pages 93~100
The effects of MgO addition on thermal expansiion coefficient and dielectric constant of mullite were studied. Thermal coefficient and dielectric constant decrease with increasing MgO content and exhibit a minimum value at 1wt% MgO. However, above 3wt% MgO content both values increase. Result of X-ray diffraction analysis how that mullite compositions which include more than 0.1wt% MgO form cordierite. Spinel is also formed as well as cordierite in the composition containing more than 3wt% MgO. The results indicate that addition of MgO affect the thermal expansion coefficient and dielectric constant of mullite substrate because of the formation of new phases; cordierite and spinel. The thermal expansion coefficient and dielectric constant are affected mainly by cordierite and spinel in the regions containing less than more than 3wt% MgO, respectively.
Microwave Dielectric Properties of CaO Added
Journal of the Korean Ceramic Society, volume 30, issue 2, 1993, Pages 101~106
Effects of CaO on microwave dielectric properties of (Ba, Pb)O-Nd2O3-TiO2 ceramic ystem were investigated. As the content of CaO increases, the sintered bulk density decreases due to the decrease of sinterability. However, with increasing the sintering tmperature, the relative dielectric constants increases. This has been attributed on the formation of the 2nd phase inclusion, TiO2(rutile). The Q values increase due to the compensation effect of Ca ions up to 1 wt%, and then decrease due to the interfacial relaxation effects. The temperature coefficient of resonance frequency increases to a positive direction with increasing the amounts of CaO.
Crystallization of Passivation Glass for Electronic Devices
Journal of the Korean Ceramic Society, volume 30, issue 2, 1993, Pages 107~114
Zinc-Borosilicate(ZnO 65.0wt%, B2O3 21.5wt%, SiO2 9.0wt%, PbO or tiO2 4wt%) passivation glasses were studied using differential thermal analysis(DTA), scanning electron microscopy(SEM) observations, X-ray diffraction (XRD) patterns and measurement of thermal expansion coefficients. Passivation glasses containing 4wt% TiO2 and 4wt% PbO had crystallization temperature of 680~73
and major crystalline phases were identified by X-ray diffraction as
-5ZnO.2B2O3. As increasing firing temperature, the size of crystalline phases increased by observation of SEM. The thermal expansion coefficient of crystallized glass frits was smaller than that of unfired glass.
A Study on the Preparation of
Journal of the Korean Ceramic Society, volume 30, issue 2, 1993, Pages 115~122
Transparent Al2O3 and TiO2 clear sols prepared by hydrolysis and subsequent peptization were mixed into wet gel. EDS analysis for this gel showed that wet gel was extremely homogeneous in chemical composition. Calcination of the wet gel at 120
for 50 minutes resulted in Al2O3-TiO2 nanocomposite powders where TiO2 particles of 101~102 nanometer were dispersed in the Al2O3 matrix. Both powders were sintered for 4 hours in the temperature range over 1500~1
with and without 5wt% MgO sintering aid. Among these sintered bodies, nanocomposite powder compacts sintered at 1
for 4 hours with 5wt% MgO showed the most dense structure with the grain size under 5
and highest relative density of 98.2%.
Synthesis and Properties of
Composites from Alkoxides
Journal of the Korean Ceramic Society, volume 30, issue 2, 1993, Pages 123~130
Dispersed type Al2O3-SiC composite powders were synthesized from Al-isopropoxide (Al(i-OC3H7)3) and Si(OC2H5)4 precursors by hydrolysis of mixed alkoxides and carbothermal reaction method. The characteristics of the synthesized (dispersed type) Al2O3-SiC composite powders were investigated using XRD, SEM, TEM, BET and particle size analyzer. Carbothermal reaction to produce Al2O3-SiC composite was completed in 10h at 135
on 3~4㎤/s (0.21~0.28cm/s) of H2 flow rate and about 1/1 of carbon/oxides(=SiO2＋Al2O3) molar ratio. The synthesized powders were observed to have the mean particle size range of 0.4~1.26
and showed finer particle size with increasing SiC content.
Injection Molding of Silicon Nitride Powders Treated with Coupling Agents
Journal of the Korean Ceramic Society, volume 30, issue 2, 1993, Pages 131~138
The effects of silane coupling agents on the injection molding process were investigated using silicone nitride mixtrues with a binder system containing polypropylene as a major binder (55vol% solid loading). The formation of bonding between silicon nitride powder and coupling agents was confirmed through the analyses of powder surface. The use of coupling agents improved mixing characteristics judged by the torque change during mixing process. the coupling agents also reduced molten viscosity of the mixture considerably, which is a main factor to determine the flow of the mixture. However, the bonding between coupling agents and polymers had a negative effect on the debinding process by retarding the thermal decomposition.
Mechanical Properties of High Strength Cement Composite with Carbon Fiber
Journal of the Korean Ceramic Society, volume 30, issue 2, 1993, Pages 139~147
Two sheets of high strength cement paste using ordinary Portland cement and water soluble polymer (polyacrylamide) were made by kneading with a twin roll mill. A carbon fiber layer out between two sheet of the cement paste, and then carbon fiber reinforced high strength cement composites were prepared by pressing them. The mechanical properties of the composites were investigated through the observation of the microstructure and the application of fracture mechanics. When the carbon fiber was added with 0.2 and 0.3wt% to the composites the flexural strength and Young's modulus were about 110∼116MPa and 74∼77GPa respectively, and critical stress intensity was about 3.14MPam1/2. It can be considered that the strength improvement of high strength cement fiber composites may be due to the removal of macropores and the increase of various fracture toughness effects; grain bridging, frictional interlocking, polymer fibril bridging and fiber bridging.
Low Temperature Deposition of TiN on the Steel Substrate by Plasma-Assisted CVD
Journal of the Korean Ceramic Society, volume 30, issue 2, 1993, Pages 148~156
TiN films were deposited onto high speed steel (SKH9) by plasma assisted chemical vapor deposition (PACVD) using a TiCl4/N2/H2/Ar gas mixture at around 50
. The effects of the deposition temperature, R.F. power and TiCl4 concentration on the deposition of TiN and the microhardness of TiN film were investigated. The crystallinity and the microhardness of TiN films were improved with increase of the deposition temperature. Optimum deposition temperature in this study was 50
, because a softening or phase transformation of the substrate occurred over 50
. A large increase of the film growth rate with a strong(200) preferred orientation was obtained by increasing R.F. power. Much chlorine content of about 10at.% was found in the deposited films and resulted in relatively low average microhardness of about 1, 500Kgf/
compared with the theoretical value(~2, 000Kgf/
Hot Pressing after Cold Cyclic Compaction of Alumina Powder Matrix Mixtures -Effects of Cold Cyclic Compaction-
Journal of the Korean Ceramic Society, volume 30, issue 2, 1993, Pages 157~163
Hot pressing after cold cyclic compaction of Al2O3 powder mixtures containing SiC whiskers or Al2O3 short fibers is studied with emphasis on the effects of cold cyclic compaction. The green density of the mixtures increases as the cycle number increases and the cyclic pressure becomes higher. The higher green density is also obtained by cold cyclic compaction with the lower pressrue than a single stroke cold compaction. To achieve a higher densification during hot pressing, cold cyclic compaction before hot pressing is more efficient compared to the conventional hot pressing process (without cold cyclic compaction). Moreover, a low cyclic pressure did not affect on toughening mechanism by whisker reinforcement.
Effect of Surface Grinding on Low Temperature Degradation of 3Y-TZP
Journal of the Korean Ceramic Society, volume 30, issue 2, 1993, Pages 164~168
Grinding of 3mol% Y-TZP enhanced the texturing of t-ZrO2, which is represented by the increased I(002)t/I(200)t peak intensity ratio, and an asymetric broadening of (111)t peak. The degree of texturing and asymetric broadening depended on a seversity of grinding. The asymetric (111)t peak broadening was resulted by the formation of r-ZrO2. When aged at 25
for 120h, r-ZrO2 transformed to t-ZrO2 due to the relief of stressed surface area and the amount of tlongrightarrowm transformation inversely varied with the I(002)t/I(200)t. The inverse dependence was interpreted by that the degree of texturing determines the magnitude of residual surface stress and the lattice relaxation of t-ZrO2, which causes the low temperature degradation, is retarded as the residual stress becomes greater.