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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Ceramic Society
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Journal DOI :
The Korean Ceramic Society
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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
A Study on the Material Resistance Against Segregation of Cement Mortar in Water
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 941~948
An underwater grout on material resistance against segregation in water were studied by water soluble polymer (methyl cellulose and acrylic acid ester and styrene). The mechanical properties of the grout agents were investigated through the observation of the microstructure and application of fracture mechanic. When the soluble polymer MC+AAES added with 0.6 wt% to the underwater grout agents the compressive strength, flexural strength and Young's modulus were about 58 MPa, 10 MPa and 3.2 GPa respectively, and critical stress intensity was about 0.8 MNm-1.5. It can be considered that the strength improvement and fracture toughness increase may be due to the pore decrease and bonding force by material resistance against segregation in water.
The Relationship between Microstructure and Freezing Thawing Resistance of Polymer-Cement Mortars
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 949~956
In order to investigate the relationship between pore size distribution and freezing-thawing resistance of mortars, polymer-cement mortars were prepared by using styrene-butadiene rubber latex, ethylene-vinyl acetate emulsion and polyacrylic ester emulsion with various polymer-cement ratios at constant flow. From the results of the test, polymer-cement mortars had a good pore size distribution for freezing-thawing resistance compared with unmodified mortars because of having a small pore volume in the pore radius range of 103~104
affecting on the frost damage. And the freezing-thawing resistance of polymer-cement mortars was improved with increasing polymer-cement ratio.
Preparation of Porous Glass by the Sintering
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 957~968
Manufacturing process of porous glass by the filler method was studied. Commercial soda-lime-silicate glass powder was mixed with inorganic salt as the filler such as KCl, K2SO4, Na2SO4. Sintering shrinkages of mixed powders with the variation of sintering temperature were compared, and the effects of the fillers to shrinkages of mixed powder were increased in the order of Na2SO4
of pore diameter were manufactured when the filler sizes 100~200
. The open pore volume of porous glass is determined by the quantity of filler and porous glasses having open pore volume between 30 and 70 vol% are available. Available sintering temperature range for preparation of porous glass is from the softening temperature of the glass powder to eutectic melting temperature of DTA curve of mixed powder.
Electrical Properties of Tape-Cast Zirconia Thin Plates with the Mixing Ratios of
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 969~974
After adding 8Y-ZrO2 powders to 3Y-ZrO2 powders at ratios of 0, 33, 50, 67, and 100% by weight, the mixed yttria-stabilized zirconia specimens were fabricated into thin plate using tape~casting method and then sintered at 150
for 4h in air. The crystalline structure, microstructure and electrical properties of the sintered zirconia thin plates were investigated by using X-ray diffractometer, scanning electron microscope and impedance analyser, respectively. At the temperatures higher than 75
, the sintered thin plate with 33% 8Y-ZrO2 content shows higher mechanical properties and lower electrical resistivity than 8Y-ZrO2 thin plate which is generally used as an electrolyte for solid oxide fuel cells. This is due to the fact that the zirconia thin plates with low 8Y-ZrO2 content maintain the slope of low temperature region up to high temperatures, whereas at temperatures higher than 50
the slope decrease in the zirconia thin plates with high 8Y-ZrO2 content.
Additives on the Characteristics of Infrared Radiator of Cordierite System
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 975~980
The thermal properties of cordierite (2MgO.2Al2O3.5SiO2)+30 wt% clay+ Xwt% MnO2 of infrared radiator have been investigated as a function of MnO2 additives (X=0,0.1,0.25,0.5,1.0,1.5,2.0,2.5). The thermal expansion coefficient was decreased with increasing amounts of MnO2 additives. Otherwise, the spectral emissivity was increased in the below 4.5
wavelength. Also, the infrared radiator of cordierite system which spectral emissivity was approximately 1.0 can be attainable at from 4.5
wavelength. The spectral emissivity was decreased from 8
Properties of Multilayer Glass-Ceramic Dielectrics
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 981~988
Crystallizable glasses with precipitation of celsian were prepared for the purpose of insulating dielectric layers for the devices such as integrated circuit substrates. Crystallization behavior of these glasses were studied by DTA, SEM, XRD analysis and by the measurement of dielectric properties. The base composition of the glass-ceramic consists in weight percent of 30% SiO2, 10% Al2O3, 26% BaO, 10% CaO, 10% ZnO, 8%TiO2 and 6% B2O3. 2-6 wt% Y2O3 were selected as the nucleating agent to promote monoclinic celsian formation. As a result, in barium-rich glasses containing 4~6wt% Y2O3 , monoclinic celsian was developed as major crystalline phase in the temperature range of 850~90
. Also, the dielectric constant and quality factor of these glass-ceramics were about 9 and more than 1000, respectively.
A Study on Packing of Regular Particles - Preparation of Dense Sintered Silicon Carbide (1) -
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 989~994
This study aims at finding the closest packings of regular shape particles such as sphere, circle rod and hexagonal rod type. As the ratio of particle size to container lowered to less than 1/10, the wall effect decreased gradually. The tap density of spherical particles with almost orthorhombic arrangement was 59.5%, while those of circle rod and hexagonal rod type particles were 63.5% and 63.0% respectively. And it was decreased with increasing the aspect ratio of regular particles. The tap density of binary mixtures was larger than that corresponding to the monosized particles packing by about 15%. The tap density of ternary mixtures was larger than that of corresponding to the packing of binary mixtures by about 9%. This work employed the binary mixture of 60% coarse particles and 40% fine particles with size ratio of 1.0 to 1/10 and the ternary mixture of 60% coarse particles, 20% medium and 20% fine particles with size ratio of 1:1/10:1/400 respectively.
Phase Relation and Microwave Dielectric Properties of
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 995~1004
Phase relation and microwave dielectric properties of the system BaO.(Nd1-xSmx)2O3.TiO2 (n=4, 5) were studied. With n=5 (1 : 1 : 5), Ba2Ti9O20 and TiO2 formed in case of X
0.7, and Ba2Ti9O20 and Sm2Ti2O7 formed at X=1.0 as the second phases dispersed in fine-grained orthorhombic matrix phase. With n=4 (1 : 1 : 4). on the contrary, only fine grains of an ortho-rhombic phase were observed irrespective of Nd/Sm ratio. The compositions of these two stable orthorombic phases having distinct lattic constants even with the same Nd/Sm ratio were estimated as 4BaO.5(Nd1-xSmx)2O3.18TiO2 and BaO.(Nd1-xSmx)2O3.4TiO2 with n=5 and n=4 in the system BaO.(Nd1-xSmx)2O3.TiO2, respectively. Consequently the composition BaO.(Nd1-xSmx)2O3.5TiO2 lies in the compatible triangle of 4BaO.5(Nd1-xSmx)2O3.18TiO2 and the second phases mentioned above. The microwave dielectric properties (~4 GHz) of BaO.(Nd1-xSmx)2O3.5TiO2 can be controlled effectively by adjusting Sm content : with increasing X from 0 to 0.7, both dielectric constant and the temperature coefficient of resonant frequency decreased monotonically from 82 to 65 and from 91 (ppm/
) to -19(ppm/
), respectively, while unloaded Q(Qo) remained constant at about 2,600.
Compounds by Coprecipitation Method and Their Electrical and Thermal Properties
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 1005~1011
The three different composition of BaTi4O9, Ba2Ti9O20 and BaTi5O11 were prepared by coprecipitation process, and then the dielectric properties of these compounds were measured at low microwave frequencies. The powder showing high level of purity was synthesised by the coprecipition reaction of BaCl2 and TiCl4 where (NH4)2CO3 and NH4OH were used as a deflocculent. Followings are the result of this study: 1. The sintering temperature increased with increasing TiO2 content. 2. BaTi4O9 powder were synthesized as a single phase by this processing technique, but the resultant Ba2Ti9O20 and BaTi5O11 phase existed with Ba2Ti9O20 and BaTi5O11 phases. 3. Single phase BaTi4O9 showed high dielectric constant value of 35, high Q value of 8100.
Complex Impedance Analysis of Nb-Doped Barium Titanate Ceramics
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 1012~1220
BaTiO3 ceramics doped with 0.1 to 4.0 mol% Nb2O5 were prepared by conventional solid stage sintering process, so as to investigate the effect of the amount of Nb2O5 on the dielectric properties and complex impedance patterns of barium titanates. From the measurement of capacitance, we found that the dielectric constant of BaTiO3 samples with 1 mol% or more Nb2O5 remained approximately constant around room temperature with values higher than 2500. In this paper, the effect of impurity content as well as temperature on complex impedance patterns was discussed in detail. In particular, the grain and grain boundary behavior of samples which showed PTCR characteristics was discussed in terms of measuring temperature.
Nanocomposites by Hot Pressing
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 1021~1029
SiC ultrafine particles of 1, 10, 20 and 30 vol% were dispersed in
-Si3N4 matrix and hot-pressed under the condition of 30 MPa at 1800 and 190
respectively. Physical, mechanical properties and microstructures of sintered Si3N4-SiC nanocomposites were investigated. Flexural strength and density of Si3N4-10 vol% SiC nanocomposites hot-pressed at 190
represented the 1002 MPa and 97.9%T.D respectively, and it was confirmed as a remarkable improvement of 67% compared to Si3N4 monolith. Fracture toughness was shown as 7.2 MPa.m1/2 when the same composition was hot pressed at 180
. This effect was supposed to be due to the improvement of microstructure by the adequate suppression of the excessive growth of Si3N4 grain with SiC nano-particles.
Effect of Pyrochlore Phase on Electric Properties for PNN-PT-PZ Piezoelectric Ceramics
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 1030~1036
The ceramics in the system 0.5[Pb(Ni1/3Nb2/3)O3]-0.5[0.65PbTiO3-0.35PbZrO3] were prepared by conventional solid state reaction method, double calcined method (columbite precursor method) and flux method using NaCl-KCl. Amount of pyrochlore phase for the calcined powders, sintering charateristrics, dielectric and piezoelectric properties were then investigated. Sintering temperature was 1000~120
and in case of flux method, the amount of flux to oxide was 1 : 1 mole ratio. The dielectric and piezoelectric properties of ceramics prepared by double calcined method and flux method were found to be better than those by conventional method. It was also possible to lower sintering temperature and reduce the amount of pyrochlore phase either by double calcined method or flux method. But with increasing sintering temperature, the difference in characteristrics due to diffrent fabrication method gradually.
Effect of annealing Atmosphere on the Piezoelectric and Mechanical Properties of PZT Ceramics
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 1037~1043
The effects of annealing atmosphere and temperature on piezoelectricity (k33) and the mechanical strength of machined PZT was studied. Morphotropic Nb-doped PZT was sintered, machined to a rod and then annealed between 80
in air, PbZrO3, and CuO atmospheres respectively. In air or PbZrO3 atmosphere, the compressive strength of Nb-doped PZT increased by 12% with little change in k33 irrespective of annealing temperature. In CuO atmosphere, on the other hand, the compressive strength increased by 20% with little change in k33 at 80
but both turned to significant decrease above 90
. The examination of the phase distribution and microstructure beneath the surface of CuO-treated PZT revealed that the changes in compressive strength and k33 are closely related to the reaction between PZT and vaporized CuO:liquid PbO precipitated in shallow surface region by the substitution of Cu to Pb sites enhances the decrease in microcracks and the surface roughness at 80
; rapid evaporation of precipitated PbO expands a porous region of changed composition into the bulk above 90
Fabrication of Porous Ceramics and Multi-layered Ceramics Containing Porous Layers; I. Pore Structure
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 1044~1052
Tape casting technique was successfully applied to produce porous ceramics and multi-layered ceramics containing porous layers, where spherical hollow polymer particles were introduced as pore precursors. In the presence of extreme differences in density and size between Al2O3 and pore precursor particles, hindered settling was effective in preventing segregation of component particles and packing behavior of mixed powders was improved through bimodal packing. There were two transitions in packing behavior of mixed powders. The first transition took place at 40~50 vol% pore precursor addition, where majority of pores changed from close to open pore state. The other transition occured at 60~70 vol% pore precursor addition, where pore precursor particles formed a continuous network structure.
on Microstructure and Mechanical Strength of Sintered Magnesia
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 1053~1059
The influence of ZrO2 addition on microstructre and mechanical strength of magnesia ceramics were discussed. ZrO2 was existed as a cubic phase resulted from MgO solubility into ZrO2 on firing at temperature range from 130
for 2 h. The addition of ZrO2 markedly promoted the densification of MgO also above 150
and the sintered density at 1
, 2 h reached to 95.2% of the theoretical. The solubility of MgO into c-ZrO2 was about 7.68 wt% and it was segregated at grain boundary on cooling to room temperature. ZrO2 existing as a second phase retarded the grain growth of MgO. The bending strength were increased to 240 MPa with the amount of ZrO2.
A Study on the Improvement of Oxidation and Corrosion Resistance of Stainless Steel by Sol-Gel Ceramic Coating; (I) Synthesis of Zirconia Sol and Fabrication of Its Thin Film
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 1060~1068
Stable zirconia sol was prepared from zirconium butoxide Zr(OC4O9)4 as a precursor and ethylacetoacetate(EAcAc) or diethylene glycol(DEG) as a chelating agent under ambient agent under ambient atmosphere by Sol-Gel process. The sythesized sol was coated on 304 stainless steel substrate by dip coating, thereafter zirconia film could be obtained by heat-treatment at
. The characteristics of coating film were determined by FT-IR, XRD, and ellipsometion peak represented Zr-O-Zr bonding of tetragonal phase was shown at 470cm-1. Crystallization of zirconia gel and film from amorphous state to tetragonal phase started at 40
, and then transformed into monoclinic phase around
. Zirconia film coated on 304 stainless steel substrate showed relatively low porosity of 16% when it was coated with 0.4M zirconia sol and thereafter heat-treated at 80
and the film was densified continuously up to 90
. The zirconia film of 10 nm thick acted as a protective layer against oxidation up to
Tribological Properties of Reaction Bonded SiC
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 1069~1075
When ceramics are used as the parts of an engine and a machine, the tribological properties are very important. For the preparation of the resistance material for wear applications by the method of Reaction-Bonded Sintering, metal silicon and carbon black are mixed up into SiC powder, and Al2O3 and Fe2O3 are put as an additive. As the general properties, the bending strength and water absortion are measured in the normal temperature and the phase changies are investigated with XRD. The property of the resistance for wear applications is measured with the amount of friction and wear, friction coefficient and maximum asperties. And, the surface of wear is observed with SEM. With the results of this study, the optimal mol ratio of Si : C and the suitable quantity of the mixture of SiC are 7 : 3 and 40 wt%, respectively. In the case of the addition of Al2O3 (2 wt%), the resistance for friction and wear applications is prominent. The bending strength showed the highest peak when Al2O3 (4 wt%) and Fe2O3 (4 wt%) were added. The properties of friction and wear were related with the propagation velocity of crack rather than the bending strength.
Synthesis of Kaolinitic Clay Mineral from Amorphous Alumino-Silicate by Hydrothermal Process
Journal of the Korean Ceramic Society, volume 31, issue 9, 1994, Pages 1076~1086
This study covers synthetic effect of the various hydrothermal treatments on formation of artificially made kaolinite mineral. The hydrothermal treatment includes the temperature treatment with time duration, addition of seeds, particle size of the starting material used, pH variation and the different types of organic acids. A colloidal silica and alumina sol which are commercially available are used for this study. A colloidal silica and alumina sol are mixed by the atomic ratio of Al/Si = 1, based on the theoretical kaolinite composition and calcined at
for 8 hours duration. It was found that the kaolinitic clay mineral was well developed; thereby, the different patterns of crystalline mineral are appeared. Spherical type as a crystal form was distinctively formed at the temperature of 20
with short duration time, while platy type as a crystal was highly yielded at 300~35
. Moreover, by adding more than 20 wt% of seed as the natural kaolinitic clay to the starting material is widely distributed and developed when 2
or less particle size of the starting material is used; also, when they are heat-treated at the temperature of 25
with 5 hours duration. With respect of the effect of pH variation on formation of the synthetic kaolinite minerals, the crystalline minerals are highly yielded at less than pH 2 and gradually diminished at more than pH9. Regarding to the effect of different acids on development of the kaolinite mineral, the organic acids with high chelating capacity produces good formation of crystalline minerals; whereas, amine radical-(NH2) is not an effective agent to generate the crystalline minerals.