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 32, Issue 12 - Dec 1995
Volume 32, Issue 11 - Nov 1995
Volume 32, Issue 10 - Oct 1995
Volume 32, Issue 9 - Sep 1995
Volume 32, Issue 8 - Aug 1995
Volume 32, Issue 7 - Jul 1995
Volume 32, Issue 6 - Jun 1995
Volume 32, Issue 5 - May 1995
Volume 32, Issue 4 - Apr 1995
Volume 32, Issue 3 - Mar 1995
Volume 32, Issue 2 - Feb 1995
Volume 32, Issue 1 - Jan 1995
Volume 1, Issue 4 - 00 1995
Volume 1, Issue 3 - 00 1995
Volume 1, Issue 2 - 00 1995
Volume 1, Issue 1 - 00 1995
Selecting the target year
Microstructure, Electric, and Magnetic Properties of Mg-Ferrite with Various Calcination Temperature
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 1~10
Effects of calcination temperature on microstructure and electric-magnetic properties of Mg-ferrite were investigated. As the calcination temperature increase, the green density and the sintered density increase due to the enhancement of densification of calcined powder. The grain size in the sintered ferrite increases with increasing the calcination temperatures from 800 to 100
, but decreases from 1000 to 120
. The resistivity decreases with increasing the calcination temperatures from 800 to 110
, but increases from 1100 to 120
due to the microstructure which consists of small, uniform grian size and pores at grain boundaries. Magnetization increases slightly due to the increasement of the sintered density while Curie temperature is almost constant regardless of calcination temperatures.
Composite Powder by SHS Method
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 11~16
High reaction heat evolved from the oxidation of Al was used to synthesize SiC, which might be difficult to be formed by SHS. Al2O3-SiC composite powder was easily manufactured using KNO3 as an ignition and reaction catalyst. Unreacted Si and C were observed after reaction dependent upon the composition of starting powders, reaction atmosphere and relative densities of compacted bodies. The unreacted carbon could be removed by calcining at
and the remaining Si could be removed by dissolving in NaOH solution. The final powder particles were smaller than 1
The Preparation of Alumina Fiber by Sol-Gel Method (I) Rheological Properties
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 17~24
The TEA complex polymeric sol was prepared by the alkoxide sol-gel method. The purpsoe of this experiment was to vefity the particle shape in the sol from the investigation of the rheological properties. TEA retarded hydrolysis rate by the reaction with alkoxide enough to make a stable transparent sol in the wide range of composition. From the results of the viscosity change with time, the optimum mole ratio for spinning was selected as 0.5 mole of TEA, 3 mole of H2O and the optimum viscosity was 104 cPs. The rheological behavior of the sol showed that the particle shape in the sol was linear, which was adequate for fiber drawing.
The Characteristics of Electromagnetic Wave Absorption in Sintered and Composite Ni-Zn Ferrites
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 25~30
The frequenc dependence of magnetic permeability(
r) and dielectric constant(
r) in MHz-GHz frequency range and their relationships with microwave absorbing properties were investigated in sintered and composite Ni-Zn ferrites, respectively. It was confirmed that zero reflection condition was required the real parts of permeability and permittivity in sintered specimen, and the complex permeability, permittivity and dielectric loss tangent in composite specimen. The real part of permittivity varied with the replacement of nickel by manganese in sintered Ni-Zn ferrite. Therefore, we could control the matching frequency and matching thickness.
Characteristics of Oxynitride Dielectics Prepared in
Ambient by Furnace
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 31~36
(100) Si was oxidized in N2O ambient, and the film properties of oxynitride dielectrics were compared with pure SiO2. The growth rate, after pre-oxidation in O2/N2 ambient with raising temperature, is faster than that of O2/N2O treatment during the same condition. Nitrogen piles up at the interface of SiO2 and Si substrate and the content is about 2atom%. Comparing with pure SiO2, oxynitride dielectrics shows less dielectric breakdown failures and flat-band voltage shift, and good diffusion barrier property to dopant(BF2) is also observed.
Synthesis and Characterization of
Ultrafine Powder by Chemical Vapor Deposition
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 37~44
TiO2 fine powders were synthesized using oxygenolysis and hydrolysis reaction of TiCl4 vapor in gas phase. The TiO2 powder synthesized showed morphological differences depending on reaction system as follows: TiCl4-O2 reaction system produced the monosized particles having polyhedral shape with well-defined crystal planes and the particles did not agglomerate into secondary particles. TiCl4-H2O reaction system, whereas, produced the spherical secondary particles which consisted of fine primary particles. Other powder characteristics such as particle size, impurity content and rutile content are also reported in this study.
A Study on the Mg-doped LAS Ceramics Using Metal Alkoxide
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 45~50
In order to densify LAS(Lithuim Aluminosilicate)system compounds, we used metal alkoxides as precursors. Also Mg was added by sol-gel method using metal alkoxides to the LAS system for improving the sinterability, thermal and mechanical properties. The result was that the synthesizing temperature was lowered about 10
, the sintering temperature was lowered by over 10
and MOR of samples from metal alkoxides was two times larger than that of sample form oxide.
Densification Behavior of
Ceramics with Grain Growth
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 51~56
Variation of sintered density of BaTiO3 powder calcined at 120
was investigated with respect to the grain growth behavior. It was found that BaTiO3 powder, which was calcined at 120
, showed abnormal grain growth behavior during sintering process. At initial stage of sintering process, the densification rate of specimen was accelerated with rapid grain growth caused by the abnormal grain growth. But with the increase of sintering time, abnormally grown grain met each other and the density of specimen decreased drastically due to coalescence of pores located in triple junction. On the contrary, BaTiO3 powder calcined at 135
showed normal grain growth behavior and gradually densified with the increase of sintering time.
Preparation and Characterization of Alumina Thin Film by Sol-Gel Method (III) Preparation of Anti-Reflective Coating Glass
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 57~62
The coating condition of reproducible anti-reflective coating film and the light transmittance characteristics of the prepared anti-reflective coating glass were investigated as a study for the preparation of single-layer anti-reflective coating glasss. In case of coating with the sol in which the solvent was substituted with the ethanol with the addition of 0.1 mol HNO3, the coated glass showed the minimum value of the refractive index of 1.464, light transmittance of 94.2% at 550nm standard wavelength which is 3.2% higher than that of the parent glass, and the reflectance in the entire wave range of visible light. The refractive index represented its minimum at the sol concentration of 1.0 mol per 100mols of water and the higher the sol concentration, the higher the refractive index, resulting in the decrease of the light transmitance. The production condition of the reproducible anti-reflective coating on glass with the maximum transmittance of 94.2% was 4cm/min of withdrawal speed, 40
and 1 hour of heat treatment temperature and time, resulting in the film thickness of 94nm.
Synthesis and Application of Nanoparticulate Aluminosilicate Sols (II) Mixed
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 63~70
A crack-free ceramic composite membrane with micropores has been synthesized by the pressurized sol-gel coating technique using the mixed Al2O3-SiO2 sols. The mixed sols were prepared by mixing nanoparticulate SiO2 and boehmite sols. These sols were more stable at lower pH, but very unstable when their copositions were in the range of 50~75mol% of SiO2 at the same pH. The mixed Al2O3-SiO2 membrane prepared from the mixed sol (0.2mol/
of solid content and pH=2) containing 40mol% of SiO2 had the mean pore radius of 0.80nm and the specific surface area of 280
/g. The nitrogen permeability through the coated Al2O3-SiO2 layer was 42
.s.Pa. It was found that the thermal stability of aluminosilicate membranes, even through similar to that of SiO2 membranes, was much improved in comparison with
A Study on the Hydrothermal Synthesis of Clay Mineral(I) Hydrothermal Treatment of the Weathered Two-Mica Granite in Kang Wha district of Korea
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 71~82
The weathered two-mica granite is widely distributed in Korea and called a kind of ground rock for kaolin. The major minerla compositions are consist of this quartz, feldspar, mica and clay mineral. At present, only a small portion of this granite is used as the material for the low-grade tile industry due to the low S.K. value and the high contents of impurities such as Fe2O3 and FeO. The low S.K. value is caused by feldspars not weathered to clay minerals. The refinement of this thus has been required for the recent shortage of the resources of high-grade one. This paper concerns an optimum hydrothermal treatment condition to refine the low-grade weathered two-mica granite of which impurities are feldspar mineral and Fe2O3. FeO components in using for the main material of ceramic industry. And then, from this result, we tried to fine out the basic formation mechanism of clay mineral from feldspar etc and develope the effectual utilization method of this.
Heat Liberation in the Reaction of
, and Binary Compounds in the Ba-Cu-O System with Water
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 83~89
, Y2BaCuO5, and binary compounds in the Ba-Cu-O system with the nominal composition of Ba2CuO3, BaCuO2, Ba3Cu4O7, Ba3Cu5O8 were synthesized to investigate the heat evolutions and crystalline phases in the hydration reaction of orthorhombic YBa2Cu3O7-
phase. The observed crystalline phases were YBa2Cu3O7-
, Y2BaCuO5, and BaCuO2, or Ba2Cu3O5＋x, and some amount of noncrystalline phase in the Ba-Cu system comounds. In contact with distilled water, YBa2Cu3O7-
and Y2BaCuO5 did not have considerable heat liberation, but in the binary compounds of the Ba-Cu-O system, the amount of total heat liberation was increased with respect to the Cu content. It might be that the reaction of high temperature superconductor YBa2Cu3O7-
with water and/or moisture originated from the unusual oxidation state of Cu ion and the presence of amorphous Ba-Cu oxide compound. The degradation of high Tc superconductor by moisture and water could be controlled by restricting the heterogeneous distribution of Tc comlposition and the formation of second phase, such as stable Y2BaCuO5, and the resulting unstable Ba-Cu oxide compound.
Microstructure Control of Sr-Ferrite by Seed Addition
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 90~94
In Sr-ferrite system, it has been attempted to inhibit the abnormal grian growth using Sr-ferrite powders synthesized by molten salt method as the matrix and the seeds, respectively. At each sintering temperature, the addition of seed more than 15% suppressed the abnormal grain growth, and the uniform microstructure resulted. Particularly, at 12
, it was observed that the maximum number of the abnormal grain growth nuclei was achieved since the abnormal grain growth was suppressed even by the addition of 10% seed.
A Study on the Improvement of Oxidation and Corrosion Resistance of Stainless Steel by Sol-Gel Ceramic Coating (II); Effect on Oxidation and Corrosion REsistance of
Stabilized Zirconia Thin Film
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 95~105
Ceria(CeO2) stabilized zirconia(CeSZ) sol was synthesized with zirconium n-butoxide Zr(OC4H9)4 and cerium nitrate hexahydrate Ce(NO3)3.6H2O as precursors and ethylacetoacetate(EAcAc) as a chelating agent under atmosphere. CeSZ films were deposited on AISI 304 stainless steel using the prepared polymeric sol by dipcoating and the coating characteristics were investigated by XRD, ellipsometry, scratch test and SEM. The CeSZ film began to crystallize from amorphous to tetragonal phase at 40
and it was not converted into monoclinic phase up to 100
by the addition of 16mol% CeO2 as a stabilizer which could suppress phase transformation of zirconia. The CeSZ films were prepared by varying the EAcAc contents and the cncentration of CeSZ sol and measured the thickness and refractive index. From these results, it was found that the EAcAc contents and concentration of CeSZ coating sol evidently affect the densification of CeSZ film. The CeSZ film coated with 0.4M CeSZ sol and heat-treated at
for 10min had thickness of 50nm and 17% porosity. The CeSZ film on 304 stainless steel effectively acted as a protective layer against oxidation up to 80
and had superior corrosion resistance in 25% H2SO4 solution for 4.5 hrs.
Effect of CuO and
Addition on the Electrical Conductivity of ZnO
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 106~112
In order to examine the effect of CuO and Al2O3 addition on the electrical conductivity of ZnO, both Al2O3 (0, 1, 2, 5, 10at.%) and CuO (1, 5at.%) were added to ZnO. Al2O3 addition (~2at.% Al) increased the total electrical conductivity of ZnO which was already decreased by CuO doping effect Above solid solubility of Al (~2at.%), ZnAl2O4 formed and the total electrical conductivity decreased due to the decrease of sintered density. Impedance measurements were used to know the reason and degree of contribution of three resistive elements, ZnO grain, ZnO/CuO, and ZnO/ZnO grain boundaries, to the total electrical conductivity changed.
Preparation of Alumina Ceramics by Pressureless Powder Packing Forming Method (II) Characterization of Sintered Body Fabricated by Pressureless Powder Packing Forming Method
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 113~119
The green body was fabricated by a new forming method, pressureless powder packaing forming method, and the characteristics of sintered specimen were investigated. It was found that alumina ceramics prepared by the present method showed porous structure with narrow pore size distribution, and in case of abrasive powder sintered body, compared with dry-pressed specimen, had the nearly same density. Especially, the specimen prepared with spray-dried granules showed the characteristic that granules were not either deformed or fractured during forming and sintering process. Therefore, it was found that this new forming method was effective method in fabrication of porous ceramics on account of easy control of porosity and pore size and its high thermal stability.
A Study on Zirconia/Metal Functionally Gradient Materials by Sintering Method(II)
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 120~130
To analyze the mechanical property and the residual stress in functionally gradient materials(FGMs), disctype TZP/Ni-and TZP/SUS304-FGM were hot pressed using powder metallurgy compared with directly bonded materials which were fabricated by the same method. The continuous interface and the microstructure of FGMs were characterized by EPMA, WDS, optical microscope and SEM. By fractography, the fracture behavior of FGMs was mainly influenced by the defects which originated from the fabrication process. And the defectlike cracks in the FGMs induced by the residual stress have been shown to cause failure. This fact has well corresponded to the analysis of the residual stress distribution by Finite Element Method (FEM). The residual stress generated on the interface (between each layer, and matrix and second phase, respectively) were dominantly influenced on the sintering temperature and the material constants. As a consequence, the interfacial stability and the relaxation of residual stress could be obtained through compositional gradient.
Transmittance and Responce Properties of the Light Transmission Controllable Films Prepared with Dipole Particles Suspension
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 131~139
In order to improve transmittance and response properties, various compositions of light controllable films were prepared by phase separation method. The optical and response properties were measured with the variation of PMMA/suspension ratio and block copolymer/light polarizing particles. According to the increase of the PMMA/suspension ratio, the separated droplets of suspension were interconnected in the film. Decay time was 2.6 sec when PMMA/suspension ratio was 0.5 : 1 and ΔT(difference of the transmittance at OFF/ON states) was reduced with increasing of the ratio of PMMA/suspension. On block copolymer/light polarizing particles ratio variation, the highest transmittance of the film was 67.4% when its ratio was 0.6 : 1 and decay time was varied from 2.15 to 46.6 sec as block copolymer content increased 0.2 : 1 to 1 : 1.
The Role of Mn on the PTCR Characteristics of La-doped
Journal of the Korean Ceramic Society, volume 32, issue 1, 1995, Pages 140~144
The role of Mn on the PTCR characteristics of La-doped BaTiO3 ceramics was studied. The calculated Ns value was increased with Mn concentration and consequently pmax and pmin were increased. The behavior of pmin was explained by the Jonker's theory, and Ns value of 6.35×1017m-2 was well agreed with the theoretical estimate of Jonker's. The value state of Mn was measured by ESR, and changed around Tc from ＋3 in tetragonal phase to ＋2 in cubic phase. Therefore, the amount of electron trap increased at Tc led to the great improvement of PTC R characteristics.