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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 30, Issue 12 - Dec 1993
Volume 30, Issue 11 - Nov 1993
Volume 30, Issue 10 - Oct 1993
Volume 30, Issue 9 - Sep 1993
Volume 30, Issue 8 - Aug 1993
Volume 30, Issue 7 - Jul 1993
Volume 30, Issue 6 - Jun 1993
Volume 30, Issue 5 - May 1993
Volume 30, Issue 4 - Apr 1993
Volume 30, Issue 3 - Mar 1993
Volume 30, Issue 2 - Feb 1993
Volume 30, Issue 1 - Jan 1993
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Structural and Dielectric Properties of
Ferroelectric Thin Film Prepared by Sol-Gel Processing
Journal of the Korean Ceramic Society, volume 30, issue 9, 1993, Pages 695~700
In this study, we prepared Pb-Ti stock solution by sol-gel processing and deposited PbTiO3 thin film on a Pt coated SiO2/Si wafer by spin coating using the stock solution. We used lead acetate trihydrate and titanium isopropoxide. The stock solution was partially hydrolized and finally a 0.25M coating solution was prepared. We achieved spin coating at 4000rpm for 30 seconds and heated the thin film at 375
for 5 minutes and at
for 5 minutes successively, first and second heating state. And the thin film was finally sintered at 90
for 1 hour in the air. The upper electrode of the thin film was made by gold sputtering and was cricle shape with radius 0.4mm. Measured dielectric constant, dissipation factor and phase transition temperature(Cuire Temp.) were about 275, 0.02 and 521
respectively. To observe ferroelectric characteristics we calculated Pr(remnant polarization) and Ec(coercive field) byhysteresis curve. Ec was 72kV/cm and Pr was 11.46
The Hydrogen Gas Sensing Characteristics of the Pd-doped
Thin Films Prepared by Sputtering
Journal of the Korean Ceramic Society, volume 30, issue 9, 1993, Pages 701~708
Pd-doped SnO2 thin films for hydrogen gas sensing were fabricated by reactive fo magnetron sputtering and were studied on effects of film thickness and Pd doping content. Pd doping caused the optimum sensor operation temperature to reduce down to ~25
and also enhanced gas sensitivity, compared with undoped SnO2 film. Gas sensitivity depended on the film thickness. The sensitivity increased with decreasing the film thickness, showing maximum sensitivities at the thickness of 730
for the undoped SnO2 and the Pd-doped SnO2 film, respectively. Further decrease of the film thickness beyond these thickness ranges, however, resulted in the reduction of sensitivity again.
Effect of Microstructural Design on the Electrical Properties of Y2O3-Stabilized ZrO2
Journal of the Korean Ceramic Society, volume 30, issue 9, 1993, Pages 717~722
Effects of microstructures on the electrical properties of ZrO2 based ceramics were analyzed by modeling layer arrangements and mixed phase structures. Single layers and alternating multilayers were made from 3mol% and 8mol% Y2O3 doped ZrO2 powders, while mixed specimen was made by blending and compacting these raw powders. After sintering at 150
for 2hr in air, AC impedance characteristics were measured. Contributiion of bulk comonent to total resistivity and its temperature-dependence were larger in 8Y-ZrO2 single layer than in 3Y-ZrO2 single layer. The multilayered specimen connected in serial to electrodes showed partial characteristics of both 3Y-ZrO2 and 8Y-ZrO2 single layers. The multilayered specimen connected in parallel to electrodes and the mixed specimen exhibited characteristics mainly of 8Y-ZrO2 single layer. The multilayered specimen connected in parallel to electrodes revealed the highest electrical conductivity near the operating temperature of solid oxide fuel cell. However, it is expected that the mixed specimen is appropriate for the applications because of its relatively high electrical conductivity with high strength expected.
Effects of the Columbite Precursors on Phase-Formation Characteristics, Microchemistry and Dielectric Properties of
Journal of the Korean Ceramic Society, volume 30, issue 9, 1993, Pages 723~730
The mechanism of formation of perovskite phase and the dielectric properties of PZMN[Pb(Zn, Mg)1/3Nb2/3O3] ceramics were examined using two different types of the columbite precursors, (Mg, Zn)Nb2O6 (MZN) and MgNb2O6＋ZnNb2O6 (MN＋ZN). The formatin of perovskite phase in PbO＋MN＋ZN system is characterized by an initial rapid formation of Mg-rich perovskite phase, followed by a sluggish formation of Zn-rich perovskite phase. On the other hand, thepyrochlore/perovskite transformation in the PbO＋MZN system proceeded uniformly with a spatial homogeneity. The degree of diffuseness of the rhombohedral/cubic phase transitionis higher in the PbO＋MN＋ZN system than in the PbO＋MZN specimen, indicating a broadened compositional distributjion of the B-site catons (Nb+5, Zn+2, Mg+2) in the PbO＋MN＋ZN system.
Study on the R-curve Behaviour in
Journal of the Korean Ceramic Society, volume 30, issue 9, 1993, Pages 731~739
R-curve measurements were performed on Al2O3(matrix)-ZrO2-SiC whisker composite and Al2O3-ZrO2, Al2O3-SiC whisker composites in the favor of comparing the effect of ZrO2 and SiC whisker, as a second phase, to Al2O3 matrix. Al2O3-SiC whisker and Al2O3-ZrO2-SiC whisker were fabricated by hot pressing at 1
, 15MPa and Al2O3-ZrO2 by pressureless sintering at 1
. A controlled flaw/strength technique was utilized to determine fracture resistance as a function of crack extension and R-curve behaviour was determined from the relationship which is KR=K0(Δa)m. R-curveresults were KR=6.173
Δa0.031 for Al2O3-ZrO2, KR=18.796
Δa0.172 for Al2O3-SiC whisker and KR=11.96
Δa0.110 for Al2O3-ZrO2-SiC whisker composite. From the analysis of R-curve and expeirmental data above three composites, it is found that R-curve behaviour of Al2O3-ZrO2-SiC whisker composite was dominated initially by the strengthening effect of ZrO2 and after, some extended crack were influenced by the effect of SiC whisker. Analysis of SEM and X-ray data revealed that whisker bridging in the crack wake and whisker pull-out mechanisms were the main mechanism for the R-curve behaviour.
Crystal Structure of
Fine Powders Prepared by Coprecipitation
Journal of the Korean Ceramic Society, volume 30, issue 9, 1993, Pages 740~746
TiO2-SnO2 fine powders prepared by coprecipitation from TiCl4-SnCl4 aqueous solution, and their crystal structures were studied. All the TiO2-SnO2 fine powders calcined at 180~
showed the complete solid solution between TiO2(rutile structure) and SnO2(rutile structure). This crystal structure of TiO2-SnO2 powders is thought to be originated mainly from the heterogeneous nucleation of Ti-hydroxde on the Sn-hydroxide with coherent structure.
Thermal Spalling and Resistance to Slag Attack in Porous High Alumina Ceramic (According to Pore Size)
Journal of the Korean Ceramic Society, volume 30, issue 9, 1993, Pages 747~753
The investigation was carried out to study the behaviors of the pore size and porosity, the mechanical strength, the resistance to thermal spallings and slag attacks according to particle sizes of starting raw materials in porous high Alumina ceramics. This porous ceramics have been used in processing of the clean steel by the blowing of the inert gas. The required properties in the practice are the suitable pores size, the sharp pores distribution for a uniform blowing of the gas, the strong corrosion resistance to slags and molten metals and the resistance to thermal spalling. The optimized properties in porous high alumina ceramics of the specimen No. 3 was found to be the very low slag intrusion and the superior resistance to thermal spalling because of the suitable pore size of 2.5
, the porosity of 30% and the high sinterability.
Synthesis and Properties of Hydroxyapatite-Zirconia Composite Ceramics
Journal of the Korean Ceramic Society, volume 30, issue 9, 1993, Pages 754~760
Hydroxyapatite(HAp)-zirconia composite ceramics were prepared by simplified synthesis process and then their properties were investigated. Composite powders of HAp and zirconia were successively synthesized under Ca/P=1.69, 1.71, 1.73 and pH=11 by precipitation method. HAp-zirconia ceramics were obtained with sintering of these various HAp-zirconia composite powders. These sintered bodies were mainly composed of HAp and ZrO2(tetragonal), but it was found that a little of HAp was decomposed into TCP as the amount of zirconia and the sintering temperature were increased. When HAp having 10~15wt.% ZrO2 content were sintered in the range of 1150 to 130
, the apparent porosity was about 7~11%. This showed that the successive synthesis process employed here had a limit to obtian more densified composite ceramics.
Physical Properties and Out-put Characteristics of Piezoelectric Transformer of
Ceramics with Addition of
Journal of the Korean Ceramic Society, volume 30, issue 9, 1993, Pages 761~767
Electrical and mechanical properties of Pb(Mg, Te, Mn, Nb)O3-PZT ceramics are investigated as a function of CeO2 addition (0 to 0.3wt%), and the output characteristics of piezoelectric transformer are also presented. The grain size decreased and the shapes of particles were more uniform with the addition of CeO2. The coercive electric field(9500V/cm), mechanical quality factor (2500) and bend strength (1065kg/
) were improved by addition of CeO2 0.2wt%. After repetition of a number of stress cycles, the degradation of k33 was not found in this sample. The voltage step-up ratio (Vdc/Vrms) of piezoelectric ceramic transformer (half wavevoltage doubler, load resistor 100M.ohm) was about 950 in a linear region, its value was relatively higher than other materials.
The Effect of the Structure of the Carbon Fibers on the Structure of the Fiber Intercalated Compounds
Journal of the Korean Ceramic Society, volume 30, issue 9, 1993, Pages 768~774
Sulphuric acid was intercalated in mesophase pitch based graphite fiber (Thornel P100 of Amoco), PAN based graphite fiber (M40 of Thoray) and PAN based carbon fiber (T300 ofThoray, TZ307 of Taekwang in Korea) by 0.4wt% CrO3/H2SO4 solution. The degree of crystallization of fibers increased P100, M40, TZ307, T300 fiber in order and their d002 values were 3.384, 3.424, 3.470, 3.493
, respectively. After intercalation P100 fiber formed 1 stage compound whose d002 value was 3.994
). Other fibers showed (002) reflection belonging to their 1 stage comound and prinstine fiber.
Preparation and Characterization of Antireflective Film in
System by Sol-Gel Method
Journal of the Korean Ceramic Society, volume 30, issue 9, 1993, Pages 775~783
TiO2-SiO2 system anti-reflective(AR) film was prepared to decrease reflectance on the glass surface. The experiments were carried out as fellow, 1) preparation & hydrolysis of TiO2-SiO2 system sols. 2) glass dipping, and 3) drying & heat treatment. We investigated the refractive index and thickness of film with viscosity, zeta-potential of sol, sol concentration, withdrawal speed, drying and heat treatment condition. As a result, we prepared good qualitative Quarter-Half-Quarter type anti-reflective film that had minimum, 0.02% and average reflectance, 0.087% in the visible region.