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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Ceramic Society
Journal Basic Information
Journal DOI :
The Korean Ceramic Society
Editor in Chief :
Volume & Issues
Volume 31, Issue 12 - Dec 1994
Volume 31, Issue 11 - Nov 1994
Volume 31, Issue 10 - Oct 1994
Volume 31, Issue 9 - Sep 1994
Volume 31, Issue 8 - Aug 1994
Volume 31, Issue 7 - Jul 1994
Volume 31, Issue 6 - Jun 1994
Volume 31, Issue 5 - May 1994
Volume 31, Issue 4 - Apr 1994
Volume 31, Issue 3 - Mar 1994
Volume 31, Issue 2 - Feb 1994
Volume 31, Issue 1 - Jan 1994
Selecting the target year
Preparation of Spherical (Zr, Sn)TiO4 Powders by Ultrasonic Spray Pyrolysis
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 465~470
Fine, spherical (Zr, SN)TiO4 powders were prepared from the aqueous solution of metal chlorides by ultrasonic spray pyrolysis. Single phase (Zr, SN)TiO4 powders could be obtained above
(=temperature of the reactor) and all powders exhibited sizes in the range of 0.1 to 2.0
and a narrow size distribution. The sintering properties of the prepared powders were better than those of the powders from solid-state reaction.
on Sintering and Microstructure of Magnesia
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 471~476
The influence of TiO2 addition on the sintering and microstructure of magnesia ceramics was studied. An excess amount of TiO2 over the solid solubility limit reacted with magnesia to form Mg2TiO4 compound above 130
. The deviation of lattice parameter of MgO was estimated to be under 0.2% when existence of TiO2 in MgO. The addition of TiO2 markedly promoted the densification of MgO at comparatively low temperature and the sintered density of about 98% of the theorectical was obtained at 150
, 2h. The densification was mainly governed by grain growth of MgO and the effect of Mg2TiO4 existing as a second phase on depression of grain growth of MgO was not exhibited.
Preparation of Yttria Stabilized zirconia Films by the Electrochemical Vapor Deposition
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 477~484
The yttria stabilized zirconia(YSZ) thin films for solid oxide fuel cell (SOFC) were fabricated by an electrochemical vapor deposition(EVD) technique using YCl3+ZrCl4+H2O gas system. The YSZ films were deposited under reduced pressure at the temperature of 1000~120
on the porous alumina substrates. The deposition rate, chemical composition and growth morphology were investigated by SEM, XRD, EDS. The growth rates of the films obeyed a parabolic rate law, representing that the growing process is controlled by an electrochemical transport through the YSZ film. The Y2O3 content of the films was about 10 mol%, equal to the composition of metal chloride reactant gases, approximately. The YSZ films were highly dense, the growing features showed columnar structure and surface morphologies were changed with the EVD conditions.
Reactive Ion Etching Characteristics of Aluminum Oxide Films Prepared by PECVD in
Dry Etch Plasma
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 485~490
The reactive ion etching characteristics of aluminum oxide films, prepared by PECVD, were investigated in the CCl4 plasma. The atomic chlorine concentration and the DC self bias were determined at various etching conditions, and their effects on the etch rate of aluminum oxide film were studied. The bombarding energy of incident particles was found to play the more important role in determining the etch rate of aluminum oxide rather than the atomic chlorine concentration. It is considered to be because the bombardment of ions or neutral atoms breaks the strong Al-O bonds of aluminum oxide to help activate the formation reaction of AlCl3 which is the volatile etch product.
Mechanical Properties of Cement Mortar with Fibers
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 491~498
A fiber reinforced grouts were made using ordinary cement mortar and high effective water reducing agent (naphthalene sulfonate) were made by addition polypropylene fiber and carbon fiber. The physical properties of the grouts were investigated through the observation of the microstructure and the application of fracture mechanics. When the polypropylene fiber and carbon fiber were added respectively with 0.03 wt% to the grouts the compressive strength, flexural strength and Young's modulus were about 60∼63 MPa, 12.2∼12.4 MPa, 4.2∼4.8 GPa and 63∼68 MPa, 12.2∼12.6 MPa, 4.8∼5.1 GPa, and critical stress intensity were about 0.77∼0.82 MNm-1.5, and 0.80∼0.87 MNm-1.5 respectively, It can be considered that the strength improvement of fiber reinforced grouts (FRG) may be due to the removal of macropores and the increase of various fracture toughness, polymer fibril bridging and fiber bridging.
Thin Films using Metal Alkoxide and Diethanolamine Complexing Agent
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 499~504
PbTiO3 thin films were prepared by sol-gel spin coating method using metal alkoxide and diethanolamine (DEA). The precipitation of the PbTiO3 sol occurred at pH 7.3 with HNO3 addition, regardless of the amount of DEA. The gelation time of the PbTiO3 sol was reduced with increasing amount of HNO3 and/or water. When the PbTiO3 films prepared by 0.2 molar coating solution were annealed at
for 30 min, dense and single phase perovskite films were obtained. Dielectric constant and loss tangent of the film were 239 and 0.01 at 1 kHz, respectively.
Compositional Effects of
Bioactive Cement on Hardening and Hydroxyapatite Formation
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 505~512
It has been reported that a biocement obtained by mixing CaO-SiO2-P2O5 glass powder and ammonium phosphate solution has biocompatibility as well as high strength. However, the compositional dependence on its hardening and hydroxyapatite formation phenomena has not been studied. Therefore, the main objective of this work is to study the effects of P2O5, MgO in CaO-SiO2 system glass on the hardening and hydroxyapatite formation. When more than 50 mole% of CaO containing CaO-SiO2 glasses was reacted with ammonium phosphate solution, CaNH4PO4.H2O crystal was formed, but the glass with less than 50 mol% of CaO formed (NH4)2HPO4 and NH4H2PO4 crystals which are derived from ammonium phosphate solution without reacting with the glasses. As the amount of P2O5 in CaO-SiO2-P2O5 glass system was increased, the formation of CaNH4PO4.H2O crystal was enhanced. When those hardened samples were reacted with tris-buffer solution, hydroxyapatite was obtained only for the sample with CaNH4PO4.H2O. While the substitution of MgO for CaO decreased the formation of CaNH4PO4.H2O crystal. MgNH4PO4.H2O crystla was formed in high MgO containing glass, which did not react with tris-buffer solution.
Effect of Tetragonal
Addition on the Mechanical Properties of
Suk-Won Kang ; Hai-Doo Kim ; Shin Kim ; Soo-Young Lee ; Dong-Soo Park ;
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 513~519
Alumina composite was fabricated by introducing tetragonal ZrO2 in alumina composite of
-alumina reinforced with in-situ formed La-
-aluminate (LaAl11O18). The powder mixture of composition (100-x)[88 Al2O3+(La2O3+11 Al2O3)]+x vol% ZrO2 was prepared with x from 0 to 40. Dense composites fabricated by hot-pressing exhibited bending strength up to 1200 MPa. The gain growth inhibiting effect of ZrO2 grains and La-
-aluminate platelets, and possibly the stress-induced phase transformation of ZrO2 have resulted in the high bending strength. The fracture toughness of the composite also increased up to 8.5 MPa.m1/2. The enhancement in toughness can be explained by transformation and microcrack toughening of ZrO2 and by crack deflection and bridging of La-
-aluminate platelets and ZrO2.
Effect of the Amount of Free Silicon on the Tribological Properties of Si-SiC
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 520~528
An investigation was carried out to understand the effect of the amount of free silicon on the tribological properties of Si-SiC. The specimens of dense Si-SiC composites with various amount of free silicon were fabricated in the temperature of 175
after molding under various pressure. Wear properties were measured by ball-on-plate wear tester under the constant weight of 4 Kgf at constant sliding speed of 500 mm/sec in water. As the result, the Rockwell hardness and fracture strength of Si-SiC composites remained nearly constant up to 16.62 vol% of free silicon in the Si-SiC microstructure. The Si-SiC composites containing the free silicon of 16.62 vol% was considered to be prominent in the tribological properties, which had the friction coefficient of 0.08 and the specific wear rate of 2.4
Kgf-1. The analysis of the wear surface indicated the complicated processes occuring on the surface such as fine polishing, abrasion, microfracture.
Evaluation of Grain Boundary Property in Oxide Ceramics by Isothermal Capacitance Trasient Spectroscopy
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 529~537
The principle of the Isothermal Capacitance Transient Spectroscopy[ICTS] were explained to measure the electronic trap levels in oxide ceramics. The measurement apparatus and the theory of the ICTS were described in detail. The trap energy evaluation was performed for the ZnO varistor and BaTiO3 ceramics. The grain boundary interface trap levels were detected at -5
in the case of ZnO varistor and PTCR samples, and the bulk trap levels were detected at 2
~60~ in BaTiO3. The trap energy levels of the above samples could be directly determined by ICTS measurement.
Hydration of Granulated Blastfurnace Slag in the Presence of Sodium Silicate
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 538~542
The kinetics and mechanism on the hydration of granulated blastfurnace slag-sodium silicate systems were studied by ignition loss, unreacted slag determination, XRD, DTA and SEM(EDS). From this experiment the following results were obtained. The amount of slag reaction was increased with the content of sodium silicate and also C-S-H, C4AH13, and C2ASH8 were formed to be the main products up to 28 days of hydration. Sodium silicate was not only an activator for slag hydration but also a binder in the hydration. The amount of slag reaction activated by sodium silicate was a nearly same for Ca(OH)2 activated slag, but it was smaller one than that activated by NaOH. However there was no difference in hydration products.
Bending Creep and Creep Fracture of Sintered Alumina under High-Temperature
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 543~551
The creep behavior and creep fracture of sintered alumina at high temperature were investigated under four point flexural test. Steady-state creep behavior was observed at low bending stress and primary creep until fracture was observed at hish bending stress. The loading history of bending stress did not affect on steady-state creep rate. Intergranular fracture was dominant for fracture of alumina at room and high temperature. However, transgranular fracture was dominant on creep of alumina under high temperature by nucleation and growth of microcracks due to residual flaws or cavities in the material.
Composite by Self-Propagating High Temperature Synthesis (SHS) and Its Pressureless Sintering
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 552~560
A composite of TiB2-Al2O3 system was successfully prepared from a mixture of TiO2, B2O3, and Al by self-propagating high temperature synthesis (SHS) with a novel characteristic, utilizing the internal oxidation heat of aluminium metal of the mixture, instead of by a conventional technique, externally heating a mixture of Ti, B and Al2O3. From a mixture with B/Ti molar ratio of =2.0, pure two phases of TiB2 and
-Al2O3 with good crystallinity and small, uniform sizes were formed. However, when the B/Ti molar ratio of the mixture goes to a value less than 2.0, in addition to the above main minerals, a small smounts of metastable phases such as TiB and Ti3B4 were formed. It was found that about 60%, the optimum green density of compacts gave their highest reaction rate and temperature during SHS process. TiB2-Al2O3 system composite with B/Ti molar ratio of =2.0 could be pressurelessly sintered even at 190
under Ar gas flows without any addition of sintering aids, showing their good properties such as 91.2% in relative density, 2750 kgf/
in Vickers hardness and 2620 kgf/
in flexural strength.
Preparation of SiC Composite by the Method of Reaction-Bonded Sintering
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 561~571
For the preparation of SiC composite, the properties of reaction sintering in the SiC-C-Si-Ti system with the titanium contents variation were investigated. Either the case of titanium additions or the case of direct infiltration of titanium in SiC+C preform, the newly formed fine-grained
-SiC, which was reacted from the molten silicon with graphite, was intergranulated between the original
-SiC particles. Also titanium disilicide (TiSi2) was discontinuously formed isolated pocket in silicon matrix. The amount of titanium disilicide was gradually increased as titanium content increase. With the results of hardness and fracture toughness measurement, SiC-titanium disilicide (TiSi2) composite represented high properties compared with the system of the infiltrated pure silicon.
The Study on Fabrication of LAS System Ceramics for Thermal Shock Resistance from Silicate Minerals: (I) Preparation of Eucryptite Powders with Sillimanite Group, Kaolin Group Minerals
Journal of the Korean Ceramic Society, volume 31, issue 5, 1994, Pages 572~580
With low thermal expansion coefficients, eucryptite (Li2O.Al2O3.2SiO2) and spodumene (Li2O.Al2O3.4SiO2) in LAS ceramic system show good thermal shock resistance. In this study, sillimanite or kaolin group silicate minerals and Li2CO3 were used as starting materials, and if necessary SiO2 or Al2O3 were added for making stoichiometrically formed specimens. By this process, eucryptite powders were synthesized and characterized. The powder mixtures of lithiumcabonate and silicate minerals calcined at 80
for 2 hrs were made into powder compacts.
-Eucryptite single phase was formed via intermediate phases of Li2SiO3 and LiAlO2 et al, by heating at 110
for 10 hrs from those powder compacts. When using the sillimanite group minerals, Virginia kyanite or andalusite was reacted to form eucryptite at 120
and CMK International kyanite were completed at 110
. When kaolin group minerals were used, it was found that the synthesizing temperature (100
-eucryptite from the mixture of New Zealand white kaolin was lower than that from Hadong pink kaolin (110
). The Microstructure of systhesized powder showed the irregular lump shape such as densed crystallines.