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 27, Issue 8 - Aug 1990
Volume 27, Issue 7 - Jul 1990
Volume 27, Issue 6 - Jun 1990
Volume 27, Issue 5 - May 1990
Volume 27, Issue 4 - Apr 1990
Volume 27, Issue 3 - Mar 1990
Volume 27, Issue 2 - Feb 1990
Volume 27, Issue 1 - Jan 1990
Selecting the target year
The Preparation and Thermal Decomposition of the Basic Zirconium Sulfate
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 707~712
The basic zirconium sulfate was prepared from ZrOCl2.8H2O and H2SO4 in the 9
aqueous solution. The pH and amount of unreacted zirconium in the solution that reacton had completed was 0.2 and 10%. As the pH was increased to 1.4 by NH4OH theresulting precipitates were the mixtures of the basic zirconium sulfate and the zirconium hydroxide although the precipitates were recovered completely. The thermal decomposition behavior of this sample has been examined by thermal analysis(TG-DTA), X-ray diffraction study, infrared spectroscopy and sulfur analysis. As a result, it was found that the precipitates have perfectly been decomposed at 85
accompanying to the release of a molecule of water below 25
and 85% sulfate at about
. The thermally decomlposed products were initially amorphous phase, which were become metastable tetragonal phase with increment of temperature and finally transformed to the stable monoclinic phase at 100
Dielectric and Piezoelectric Properties on Pb(
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 713~720
The effects of substituting Zn+2 for Ni+2 ion on dielectric and piezoelectric prooperties of Pb(Zn1/3Nb2/3)O3-Pb(Ni1/3Nb2/3)O3-PZT ceramics were investigated. With increasing Zn2+ contents the tetragonality was appreciably enhanced and the grain size decreased. Both Curie temperature and thermal stability were increased with increase in Zn2+ contents since the Zn+2 partial substition for Ni+2 could form solid solution in almost range of the composition investigated. Piezoelectric prooperties showed the maximum(
0=5014, kp=0.56, d31=250
10-12m/V) in 4.5Pb(Zn1//3Nb2/3)O3-40.5Pb(Ni1/3Nb2/3)O3-55PZT composition sintered at 125
and then decreased again due to the phase boundary movement for tetragonal phase of the solid solution of Zn2+ amount.
Study on the Biocompatibility of Hydroxyapatite Bioceramics : (II) Behavior in Simulated Body Fluid and Biocompatibility
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 721~728
Hydroxyapatite powders were synthesized with Ca/P=1.67 and pH=11 by precipitaton method, after characterization of these specimen, behavior in Ringer's solution and biocompatibility of hydroxyapatite, such as cytotoxity test and implantation test, were investigated. The hydroxyapatite ceramics had structural stability in Ringer's solution, and hydroxyapatite ceramics did not prevent cell growing and exhibit any cytotoxic effects. In implantation of hydroxyapatite ceramics into muscle under abdome of guinea pig, hydroxyapatite ceramics did not show any symptom of rejection for cellular texture.
Microstructural Effects Influencing the Thermal Conductivity of High-Temeprature Insulation Firebricks
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 729~734
The microstructural dependence of thermal conductivity of a high-alumina (ca. 70%) heat-insulating frebricks(ca. 75%porosity) was investigated under special consideration of the tailored-pore shape effects. Pores different shape could be incorporated into the insulators through pore formers : Styrofoam produces spherical pores while saw dust results in parallel plate pores. Concerning the pore-shape effectiveness of thermal insulation, the specimen with irregular plate pores showed much lower values of heat conductivity than those with spherical pores, the values being 0.31 to 0.38 at
and 0.35 to 0.47 at 100
, respectively. On the contrary, however, other material properties such as strength and softening temeprature under load were turned out to be better in the case of the spherical pores.
The Change of Microstructures by Low Temperature Aging in Y-TZP
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 735~740
The phase transformation of Y-TZP by low temperature aging treatments and its related behaviors of crack formation were investigated. The kinetics of phase transformation was greatly dependent on the amounts of Y2O3, grian size and microstructures of sintered body. The phase transformation happened to start at specimen surface and near the pore in the first place, where the change of strain energy during the phase transformation was small and the water vapor that accelerated phase transformation easily diffused.
The Role of Calcium as a Reduction Inhibitor in
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 741~746
Dielectrics which do not lose their high insulation resistance in reducing atmosphere are necessary for multilayer ceramic capacitors with Ni internal electrode. In this study we investigated the Ca ion site occupancy in A-site excess Ca-doped BaTiO3 by measuring the insulation resistance, lattice constant and Curie temperature. Its Curie temperature, which was lower than that of the pure BaTiO3, was more lowered by sintering in reducing atmosphere. Lattice constnat of c-axis decreased and that of a-axis increased, suggesting substitution of Ca ions for Ti ions. Hence CaTi" acts as an acceptor to maintain high insulation resistance.ance.
A Study on the Preparation of Alumina Powders from Bauxite by Wet Acid Process and Their Utilization(I) : Preparation of Aluminum Hydrate Gels from Bauxite
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 747~754
Aluminum hydrate gels were prepared from the mixtures of bauxite and ammonium sulfate by wet acid process. Optimum conditions for obtaining the maximum yield( 99%) of aluminum hydrates from the same amount of bauxite were confirmed as follows ; 1. Mixing ratio ; addition of 25mole% of ammonium sulfate to 1mole of bauxite. 2. Calcination ; heated at 350℃ for 1hr. 3. Extraction ; leached at 95℃ in 1% H2SO4 for 90min. 4. pH of precipitating solution; slight below 7.0. Amorphous aluminum hydrates were precipitated at the pH lower than 8.5, but the precipitates crystallized to bayerite at the pH was 10. Mean diameter of α-Al2O3 powders which were obtained by calcining the aluminum hydrates was below 0.2㎛, and EDS analysis revealed than SiO2 was it's primary impurity.
Effect of Oxygen Partial Pressure on Tungsten-Alumina Bonding Behavior
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 755~762
The tungsten paste was printed on the surface of 92% alumina sheet which was made by type casting process. The printed tungsten was bonded on the Al2O3 by co-firing in reducing atmosphere. During the co-firing, the binder burn-out was easier in wet H2 atmosphere than in dry H2, which affected sintered density. In practically, the use of wet H2 above 100
was beneficial for density of alumina and bond strength. This phenomena occured more distinctly when atmosphere varied from dry H2 to wet H2 than varied dew point in wet H2. In wet H2, the improvement in bonding strength can be attributed to good glass migration into the metal layer due to inhibition of the tungsten particle growth, with increase of alumina density, at the temperatrue higher than 100
The Effects of Tin in Bottom Surface to Ion Exchange of Float Glasses
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 763~768
The gradient and depth of tin at the side of glasses by float process were measured. The effects of tin to ion exchanged of glasses in the molten salt of KNO3 and AgNO3 were presented by means of Ag+ ion penetration depth, diffusion coefficient variation, spectral transmittance and color coordinates. The diffusion coefficient of Ag+ ion of tin side was higher than air side, and the activation energy of tin side was 0.2-0.6Kcal/mole lower than air side. Therefore Ag+ ion penetration depth of tin side is 2-10
deeper, hence it can be seen that tin promote Ag+ ion diffusion. The same treatment of ion exchange, reddish-brown oflong wavelength in case of tin present, yellowish-amber of short wavelength in case of tin absence were revealed.
Study on Refinement of Hwasun Flint Clay
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 769~776
This study deals with the refinement of Hwasun flint clay by grinding, classifying, magnetic separation and acid treatment in sequence. Results are as follows ; 1. Fine kaolinite particles of median size in the range of 4.8 and 1.7
was collected, with the yield of 87.4% by dry grinding and classifying process. 2. It is proven that the iron bearing are of Hwasun flint clay is mainly consisted of chloritoid and iron rich muscovite. 3. As the results of the high gradient magnetic separation, the bleaching and iron removal degree of the dry grinding and classifying sample was 4-58% and 5-62% respectively. 4. As the results of the acid treatment, bleaching and weight loss degree of the dry grinding and classifying sample was reduced to 16-82% and 6-29% respectively.
Synthesis and Sintering of Cordierite from Metla Alkoxides (II) Sintering
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 777~782
The sintering behavior of cordierite powders synthesized using a sol-gel method of metal alkoxides Si(OC2H5)4, Al(OC3H71)3 and Mg(OC2H5)2 was investigated. Densification of the powder compacts fabricated using the precursor powders calcined at 900
for 2hrs was improved over the sintering temperature range of 800 to 980
. The powder compacts, fabricated using the calcined precursor powders and sintered at 1300
for 2hrs, showed relative density of 97-98%, 3-point bending strength of 120-140Mpa, KIC of 2.4-3.7 Mpam1/2, and thermal expansion coefficient of 1.48-1.66
Sapphire Ribbon Single Crystal Growth by EFG Method
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 783~789
Shaped crystal growth apparatus were made for sapphire ribbon single crystal growth. Sapphire ribbon single crystal are grown by EFG(Edge-defined Film-fed Growth) methdo for use as watch-glass and SOS(Silicon-On-Sapphire) devices. Sapphire ribbon crystals were grown to be 40min wide, 1.8mm thick, 96mm long. Therelationshiops between growth striation and surface roughness, with various growth rates, were investigated and compared. It was found that sapphire ribbon crystal is suitable for watch-glass by measuring the transmittance in the visible light region.
Characteristics of Alumina Film Prepared by MOCVD
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 790~798
Al2O3 film was chemically deposited by pyrolytic decom,positio of the Al-tri-isopropoxide/N2 system at 350
, 30 and 1.86torr. FTIR analysis showed a deposited film was a hydrated alumina and transformed to an anhydrous one after heat treatment(1hr, >800
or 4hr, >500
) in N2 atmosphere. This transformation influenced on the CV-hysteresis of Si-Al2O3 structure. Also, a pH sensitivity of EIS(Electrolyte-Insulator-Semiconductor)structure using Si-Al2O3/SiO2 film was 50mV/pH in the range of pH 3 to 7.
Effects of Oxide Additions on Mechanical Properties and Microstructures of AlN Ceramics Prepared from Al-isopropoxide
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 799~807
In this study, effects of oxide additives on mechanical properties and microstructure of A1N and A1N polytype ceramics were investigated. Fine A1N powder was synthesized by nitriding alumiuim hydroxide prepared from Al-isopropoxide, at 1350
for 10h in N2 atmosphere. By adding 3w/o Y2O3, 0.56w/o CaO, and 10w/o SiO2 to AlN powder, AlN and AlN polytype ceramics were prepared by hot-pressing under the pressure of 30 MPa at 1800
for 1h. AlN ceramics with no additives formed considerable amount of AlON phase, while AlN ceramics doped with Y2O3 or CaO decreased AlON phase and formed Y-Al or Ca-Al oxide compound. AlN＋10w/o SiO2(＋3w/o Y2O3) composition produced AlON and AlN polytype compound having 21R as a major phase. Room temperature flexural strength of AlN ceramics with no additive was 246MPa, and room temperature flexural strength and critical temperature difference by thermal shock(ΔTc) of AlN ceramics dooped with Y2O3 or CaO were 532MPa/340
, respectively. Y2O3 and CaO used as sintering agent played roles of densification and oxygen removal of AlN ceramics, and affected grain growth/grain morphologies of AlN ceramics.
The Thermal Behavior of Transformation by Simultaneous
Seed Addition on the Al-Sec-Butoxide Hydrolysis
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 808~816
The thermal behavior of transformation and characteristics of seeded sample powders prepared by simultaneous
-Al2O3 seed addition with water on the Al-sec-butoxide hydrolysis were studied.
-Al2O3 seed particles are shown to act as nuclei for transformation of
-Al2O3 and to result in an increase in thetransformation kinetics and lowering of the transformation temperature by as much as 143
. Simultaneous seed addition on the hydrolysis resulted in uniform dispersin and creation of nucleation site on seed surface and only 0.1wt% seeding lowered the transformation temperature by as much as 115
. For 3wt% seed addition,
-Al2O3 single phase was obtained at 95
for 100 minutes and the specific surface area of products were lowered to 11.9
/g as compared with that of
-Al2O3 powder prepared without seed at 115
/g due to depression of vermicular structure growth.
Pilot Scale Experiments on the Oxidation of
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 817~823
Pilot-scale experiments on the oxidation of TiCl4 to produce TiO2 were carried out in a verical reactor of 20cm in inside diameter and 140cm in length ; LPG burning was used as a heating means to maintain the reaciton temperature. The effects of reaction temperature and excess oxygen content on the conversion of TiCl4 and on the particle size of produced TiO2 were investigated. The ranges of operating conditions varied were 900 to TiO2 was 0.45-0.57
, TiCl4 conversion was 82-96%, the rutile content was 33-57% and the contents of impurities were 0.03% of Fe, 0.03% of SiO2 and 62ppm of Cl. These experimental results were compared with those of other investigators.
Ceramic Fiber Fabrication by Sol-Gel Processing
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 824~828
Zirconia gel fibers were fabricated by sol-gel processing using zirconium alkoxides and 2, 4-pentanedione. Their phase transformation and microstructural evolution were studied after heat treatments up to 150
. Tetragonal ZrO2 began to form at 50
and followed by monoclinic, tetragonal phase during subsequent heat treatments at 1000, 150
for 1hour respectively. During cooling from 150
, cracks were created, propagated along grain boundaries due to the volume change from tetragonal to monoclinic transformation.
Reply on "Growth of Superconductor
Single Crystal by Flux Method"
Journal of the Korean Ceramic Society, volume 27, issue 6, 1990, Pages 829~830