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 26, Issue 6 - Jun 1989
Volume 26, Issue 5 - May 1989
Volume 26, Issue 4 - Apr 1989
Volume 26, Issue 3 - Mar 1989
Volume 26, Issue 2 - Feb 1989
Volume 26, Issue 1 - Jan 1989
Selecting the target year
Reinforcement of Concrete Structure by Impregnation of Molten Sulfur
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 729~736
This study aims to reinforce concrete structure by impregnation of molten sulfur. The improved properties of sulfur impregnated concerete were confirmed by compressive strength test and water proof effect. Following variables were adopted to evaluate impregnation parameters ; 1) the effect of water content in concrete structure (0-8%) 2) impregnation time of molten sulfur(0-22hr) 3) impregnation temprature of molten sulfur(13
). In partial ponding experiments, the concrete specimen of sulfur impregnated by 2wt% yields 1.5 times higher value of compressive strength than that of control one(non-impregnated concerte). In complete ponding experiments, the mortar specimen of slufur impregnated by 12-14wt% yields 2-3 times higher value of compressive strength than that of control one (non-impregnated mortar). From the examination of X-ray diffractions,
-sulfur was found in concrete pores. Homogeneous impregation of molten sulfur into concrete pores was also identified with poresize analysis and micrographs of SEM.
Effects of Heat Treatment on the Composition and Magnetic Properties of the Hydrothermal-Synthesized Ba-Ferrite Powder
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 737~746
After Ba-ferrite powders synthesized hydrothermally and its heated powders were dissolved partially with HCl treatment time, the BaO/Fe2O3 mole ratio of dissolved solutions and powders were measured by AAS, also, lattice constants, particle morphology and magnetic properties in HCl treated, heated and no-heated Ba-ferrite powders were abtained by means of XRD, SEM and VSM, respectively. From above analysis results, the effect of Ba/Fe mole ration in suspension(as starting material) on the BaO/Fe2O3 composition and particle characteristics of products were investigated, and the effect of heat treatment on magnetic properties of products examined. The composition, lattice constant and crystal phase of products depend on the Ba/Fe mole ratio in suspension. Ba content in surface or outer part of Ba-ferrite powder is higher than inner and heterogeneous, and the excess Ba ions in the inner part of particle move into the outer by heating, so that the mole ratio of BaO/Fe2O3 in the more jinner approaches more to the stoichiometric composition 1 : 6. The crystallinity, coercivity and saturation magnetization of products are increased by heat treatment, and the heat-treated samples synthesized hydrothermally in lower temperature are appreciated to have better powder characteristics.
The Effect of CuO and SiO2 on the Magnetic Properties of Sr-Ferrite
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 747~754
The effects of CuO and SiO2 on the sintered density, grain growth and magnetic properties of Sr-ferrite were investigated. The sintered density of Sr-ferrite is increased with increasing the amount of CuO or SiO2 addition. The grain of Sr-ferrite grow uniformly with the addition of CuO, so remanence increases and coercivity decreases. The addition of SiO2 increase coercivity but does not affect remanence prominently. The sintering temperature above 125
and SiO2 addition above 0.8wt% causes abnormal grain growth in Sr-ferrite. When CuO and SiO2 are added simultaneouly, remanence does not decrease but coercivity shows low value.
Pyroelectric Properties on Pb(Sn1/2Sb1/2)O3 Modified PZT Ceramics
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 755~762
A pyroelectric ceramic material based on Pb(Sn1/2Sb1/2)O3 modified PZT system is studied as a function of the amount of Pb(Sn1/2Sb1/2)O3 and PbTiO3. With increasing the Pb(Sn1/2Sb1/2)O3 amount the dielectric constant increases up to 10mol% and then decreases, but the pyroelectric coefficient decreases and as the PbTiO3 contents increase in the 10mol% added PZT system, the dielectric constant increases but the infrared sensitivity decreases. The good pyroelectric material has low dielectric constant and no pyrochlore phase, but does not depend in the amount of remanent dipole, and its composition sites around ferroelectric-to-antiferroelectric phase boundary.
Synthesis of Mullite Powder from Alkoxides and Its Properties
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 763~770
A very fine and pure mullite powder of the stoichiometric composition was prepared from aluminium isopropoxide and tetraethylorthosilicate by an alkoxide hydrolysis method using NH4OH as a catalytic agent. The gel powder obtained from the hydrolysis was calcined at 80
. The average particle sizes of the powders calcined at 80
, respectively. The specific surface areas of the powders calcined at 80
/g and 20.6
/g, respectively. The bending strength and fracture toughness of the mullite ceramics sintered at 1
were 263.1MPa and 2.30MPa.m1/2 respectively.
Synthesis of Sialon by Carbothermal Reduction of Porous Glass
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 771~782
-Sialon powder was attempted with carbothermal reduction of porous glass. The porous glass was prepared by heat and hydrothermal treatments of 9.32 Li2O.46.5B2O3.37.2SiO2.6.98Al2O3 glass. Carbon pyrolyzed from propane gas was deposited on the porous glass, thereafter activated carbon was added as reducing agents. The synthesized
-Sialon powder was pressureless sintered at 175
for 1hr in N2 atmosphere. The characterization of the
-Sialon powder was performed with XRD, BET, SEM and particle size analysis. The sinterability and mechanical properties of the sintered bodies were investigated in terms of bulk density, M.O.R., fracture toughness, morphology of microstructure and etc. The reduction effect of deposited carbon was better than that of activated carbon mechanically added. The formation of SiC was precominant over that of Si2ON2 and
-Sialon owing to low partial pressure of N2 inside the pore, wehreas on the surface of porous glass the formation of Si2ON2 and
-Sialon were predominant. Thereafter, SiC reduced unreacted glass to be
-Sialon. Single phase of
-Sialon(Z=1.92) was obtained from PGA porous glass having the largest pore radius by the simultaneous reduction and nitridation method at 145
for 5hrs. The bulk density, M.O.R., and KIC of the sitered body are 3.17g/cc, 434.4MPa and 4.1MPa.m1/2, respectively.
Effect of Abnormal Expansion in the Equimolecular Mixture BaCO3 and TiO2 Added Excess BaCO3
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 783~788
The reason of abnormal expansion in BaTiO3 synthesized in the equimolecular mixture and synthesized in Ba-rich region were investigated at the point of crystal and microstructure. The shrinkage and the expansion of the mixtures in BaCO3-TiO2 system were determined by the mass of BaCO3 added to the equimolecular BaCO3 and TiO2, Ba2TiO4 which was much formed and BaTi2O3 were important crystal in the reaction of Ba-rich region. Sintering phenomena of unreacted BaCO3 activity and the secondary phase caused to generate microcracks in the specimens.
A Study on the Ceria Stabilized Tetragonal Zirconia Polycrystals(Ce-TZP)(II) : Mechanical Properties of Ce-TZP and its Fracture Behavior at Elevated Temperature
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 789~794
The high-temperature strength of Ce-TZP was measured at 200, 650 and 100
by 4-point bending test. And its fracture behavior was observed by SEM. Below
of the temperature, where monoclinic fraction was almost zero, the decreasing rate of bending strength was relatively slow, but above this temperature, high temperature strength was largely decreased as a result of the decrease of stress-induced transformation of zirconia. The observation of fracture surface bended at 100
indicated that the fracture mode changed from intergranular-into transgranular-form with regardless of ceria contents.
Preparation of Polycrystalline Mullite Fiber Using the Sol-Gel Technique
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 795~801
The polycrystalline mullite fiber was synthesized from various combination of starting materials including metal alkoxides and colloidal sol by the sol-gel process. The best spinnability was observed in the sol which showed shear thinning and hysteresis (i.e., thixotropic flow), indicating that the network structure was broken down as the shear rate increased. The mullite fiber was polycrystalline after firing and characterized by thermal analysis, XRD, FT-IR spectroscopy, rheological measurements, and SEM.
The Characteristics of Piezoelectric Strian Constants on PNN-PZ-PT Ceramics
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 802~810
The temperature dependence of piezoelectric strain constant and the electric field induced strain are investigated as a function of PT in 0.5[xPT-(1-x)PZ]-0.5PNN ceramics. The piezoelectric strain constant d31 has the highest value(360
10-12m/V) at PT=0.68. The temperature dependence of d31 is improved as Curie temperature of sample is increased, and the electric field dependence of induced strain is decreased with the coercive field increased. This ceramic system shows both piezoelectric effect and electrostrictive effect under the applied electric field. The piezoelectric of tetragonal phase is higher than that of rhombohedral phase, and the magnitude of electrostrictive constant is appeared in the order of morphotropic, rhombohedral and tetragonal phase. The piezoelectric strain constant with applied field must be considered theelectrostrictive effect due to 90
domain wall displacements, and the displacement of bimorph type actuator agrees with the calulated value well.
Effect of Al2O3 on the Structure and Properties of Bioglass
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 811~819
There have been many studies on the biological phenomena of Bioglasses, which nay be used as implant materials in human body. However, not many works on the Bioglass compositions have been reported. In the present study, the effect of Al2O3 substitution for SiO2 in Bioglass of Na2O-CaO-P2O5-SiO2 system on its structure and properties was examined. Infrared and Raman spectroscopic studies for the glass structural analysis, differential thermal analysis and X-ray diffraction analysis for crystallization of the glass were perfomed. Several physical properties, such as thermal expansion coefficient, softening point, microhardness and reaction phenomena, were also measured. The major crystalline phase, after heat treatment of the glasses, was Na2Ca2(SiO2)3 and the crystal was transformed into other phase with increased substitution of Al2O3. The added Al2O3 reduced non-bridging oxygen in glass structure and thermal expansion coefficient, but increased glass density, sofening point and microhardness. When the glasses are reacted in Tris-buffer solution, the substituted Al2O3 inhibited the formation of hydroxyapatite on the Bioglas surface, and no hydroxyapatite was formed for the sample which contained more than 6wt.% of Al2O3 even if they were reacted for 600 hours.
The Study for Precipitation of Strontium in BaTiO3 by Direct Wet Process
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 820~828
The reaction mechanism formed from TiCl4, BaCl2 and SrCl2 solution by direct wet process was studied. The reaction mechanisms of BaTiO3 and SrTiO3 were published, and then the purpose of this experiment as series for direct wet process is to elucidate precipitation-relation of barium and strontium. Though the basic reaction mechanism is similar to that of BaTiO3 and SrTiO3, the amorphous (Ba, Sr)-O-Ti bonding is identified by FT-IR spectrum. Precipitation-rate of barium in (Ba, Sr)TiO3 is lower than that in BaTiO3 and precipitation-rate of strontium in (Ba, Sr)TiO3 is the same of that in SrTiO3, but the precipitated quantity of barium and strontium in (Ba, Sr)TiO3 is smaller than that in each reaction system. Especially, it is identified that critical pH for crystallization of BaTiO3, SrTiO3 and (Ba, Sr)TiO3 is at pH 12.6
Preparation and Characterization of Solder Glass for Electronic IC Package
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 829~835
Devitrifing solder glasses in a specific group of glass ceramic materials are extensively used in hermetically sealing alumina electronics packages. Preferred frit glass compositions of this study consist of 37~40wt% PbO, 35~40wt% ZnO, 18~20wt% B2O3, 1~3wt% SiO2, 0~6wt% TiO2. The coated frit glasses crystallize during firing and form a strong hermetic seal. DTA and X-ray diffraction were used to characterize crystallization of the glass frit. Frit seal containing 2wt% TiO2 has crystallization temperature of 550~57
with surface nucleation. Frit seal containing 6wt% TiO2 has crystallization temperature of 515~5
with bulk nucleation, and the main crystalline phase was perovskite lead titanate having minus expansion coefficient. The average activation energy for the crystallization calculated from Ozawa equation was 65
Characterization of Finely Divided V2O5 Particles Synthesized by Flame method
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 836~842
In this study, finely divided vanadium pentoxide was prepared by carrying vapor of vanadyl trichloride into the flame of an C3H8-O2-H2 with a specially designed burner. The flame-synthesized oxide particles had a nonporous spherical shape with nearly constant diameter in the range of 200-600
. The surface area of these particles depends on the residence time and the concentration of metal chloride vapor in the burner. The experimental results showed that the growth of particles is controlled by fusion rather than collision. The crystal size of finely divided V2O5 particle was increased after calcination at temperature above 50
Effect of Bi2O3/Li2CO3 on Low Temperature Sintering and Dielectrics of BaTiO3 Ceramics
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 843~849
Effect of Bi2O3/Li2CO3 on low temperature sinteirng and dielectric property of BaTiO3 ceramics has been investigated. For the specimen sintered at 110
, it was densified to 96% of BaTiO3 theoretical density by the addition of 1.0-1.25w/o Bi2O3/Li2CO3. Maximum dielectric constant increased and Curie temperature lowered with the increase of Bi2O3/Li2CO3 content, which probably can be explained by thne substitution of Bi3+, Li1+ on BaTiO3 lattice. The volatilization of Li1+, resulting from the increase of soaking time at 110
leads to the increase of Curie temperature and tetragonality of the specimen.
Elastic Moduli and Dissolution Rates of Resorbable Na2O-MgO-P2O5 Bioglasses
Journal of the Korean Ceramic Society, volume 26, issue 6, 1989, Pages 850~854
The elastic moduli and dissolution rates of 15 glasses with different mole ratios of sodium-magnasium-phosphate as potential non-toxic biomaterials were investigated. In this study, a 3-pint bending test, sonic resonance technique, and theoretical calculation were used to evaluate the modulus of elasticity. The dissolution rates at 37
(human body temperature) were determined by the measurement of mass changes in each sample for 24 weeks.