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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 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
Selecting the target year
Toughening of Ni Bonded
by Mo Particulates
Journal of the Korean Ceramic Society, volume 30, issue 6, 1993, Pages 429~432
Cr3C2 material is characterized by high chemical stability and poor sinterability with low strength [50~150MPa]. In his study, low melting temperature nickel powder was used to improve sinterability as well as strength. In addition, molydenum particles were added to the Ni-bonded Cr3C2 cermet pseudomatrix to increase resistance to fracture. The specimens made by hot-pressing under vacuum and strength was measured by 4-point bending. Indentation cracking and fractographic examination were conducted to study the interaction of the indentation cracks with the reinforcing particles. Toughening mechanisms and failure will be discussed in terms of crack/particle interactions and compared with previous works.
Journal of the Korean Ceramic Society, volume 30, issue 6, 1993, Pages 433~440
The bioactivity of glasses in the CaO-SiO2 system and CaO-P2O5-SiO2 system with less than 10mol% of P2O5 was investigated by in vitro test in simulated body flood(SBF). The formation of Ca.P film and hydroxyapatite on the surface of glasses after in vitro test was analysed by X-ray photoelectron spectoscopy (XPS), fourier transform infrared reflection spectroscopy (FT-IRRS), energy dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) observation. In the early stage of Ca.P film formation after in vitro test for CaO-SiO2 and CaO-P2O5-SiO2 glasses, the rate of Ca.P film formation on the surface of the glasses was dependent of structural parameter (Y) evaluated from the glass composition. First, in the case of the glasses having Y value below 2, Ca.P film and SiO2-rich layer were formed simultaneously, and there were no differences of the rate of Ca.P film formation in terms of the Y values. Second, in the case of the glasses having Y value above 2, the SiO2-rich layer was formed, and then Ca.P.Si mixed layer was formed in the silica gel structure of the SiO2-rich layer, and finally the Ca.P film on the surface of SiO2-rich layer. The rate of Ca.P film formation delayed as the Y values increased. The rate of hydroxyapatite formation of glasses (the rate of transformation from Ca.P film to hydroxyapatite) seems to be propotional to the rate of Ca.P film formation and Y value. The rate of hydroxyapatite formation of glasses belonging to the second group was delayed as structural parameter increased, and the hydroxyapatite crystal showed spherical growth in the early reaction stage, and then showed silkworm-like linear growth as the reaction time increased.
A Study on the Structural Properties of rf Magnetron Sputtered
Journal of the Korean Ceramic Society, volume 30, issue 6, 1993, Pages 441~448
The Ba1-xSrxTiO3 thin films deposited on ITO-coated glass substrate at 55
by rf magnetron sputtering method have individual preferential orientations as a function of composition (X=0, 0.25, 0.5, 0.75, 1) due to the stress relief interactions among the intrinsic compressive stress, thermal tensile stress adn extrinsic compressive stress (compressive stress in case of BaTiO3(Tc=12
) and Ba0.75Sr0.25TiO3(Tc=57
)). This behavior also appears on the (BaSr)TiO3 thin films (X=0.5) deposited on ITO-coated glass substrate at deposition temperature between 35
. The composition of Ba1-xSrxTiO3 thin films deposited on ITO-coated glass substrate at 55
is close to stoichiometry (1.009~1.089 in A/B ratio), but the compositional deviation from a stoichiometry is larger as SrTiO3 is added. The morphology of Ba1-xSrxTiO3 thin films is very similar for over all substrate temperatures, and the roughness due to the differences of cluster size is the smallest at X=0.25.
Compaction and Sintering Behavior of Zirconia Powders : II. Sintering Behaviour
;;;;;Frank L. Riley;
Journal of the Korean Ceramic Society, volume 30, issue 6, 1993, Pages 449~456
Sintering behaviour of zirconia powders prepared by different processing treatment was discussed. About >99% densities of theoretical were obtaiend on sintering at 140
for 2h in case of 300MPa uniaxially cold-pressed compact. But the lower densities were obtained on sintering above this temperature due to abnormal grain growth enabling the tetragonal to monoclinic phase transformation during cooling resulted in microcracks. All kinds of different dried powders exhibited nearly the same shrinkage behaviour with end-point shrinkage between 19 and 20%, and had maximum shrinkage rate (0.99~1.27%/min) around 120
. During whole sintering process densification was mainly governed by grain growth and rearrangement of agglomerates. Heterogeneous abnormal grain growth and abrupt decrease in shrinkage were observed when continuous interagglomerate pore collapsed into isolated pores.
Thermo-mechanical Properties and Microstructures of
Journal of the Korean Ceramic Society, volume 30, issue 6, 1993, Pages 457~468
In oxide matrix-SiC(W) composites, instability and glassy phase formation due to oxidation at the high temperature and the diffusion of Si, respectively, cause brittle fracture and low reliability for ceramic materials. The mode of contribution in each mechanisms induced by matrix-whisker debonding, varies with the morphology of matrix-whisker interfaces. This work has described the dispersion behaviours and stabilization mechanisms in slip systems, and multiple toughening mechanisms by dint of two second phase different from each other when spherical ZrO2 and chemically stable Al2O3(W) is respectively added in Al2O3 matrix. To obtain complexshaped components, slip casted bodies were sintered at 1
, 2hrs up to 98~99% R.D.. Multiple toughening mechanisms in comparison with theories reported until now will be discussed as a result of the phase analysis of ZrO2 by athermal behaviours and microstructural characterizations as well as measured mechanical properties.
Interpretation of Stresses in the Glass Bonded Ferrites by Vickeres Indentation Method
Journal of the Korean Ceramic Society, volume 30, issue 6, 1993, Pages 469~477
Residual stresses is one of the major factors to degrade the magnetic properties of VCR magnetic heads. Vicker's indentation technique was adapted to estimate the residual stresses Residual stresses and distribution in the glass and ferrite were obtained after bonding ferrite with glass, varing the cooling rate. The compressive and tensile stresses were developed in the interface and gradually decreased with increasing distance from the interface. The stresses were decreased with a cooling rate. The mean values of residual stress in ferrite were 10MN/㎡, 8MN/㎡, 5MN/㎡ with cooling rate 10℃/min, 5℃/min, 1℃/min respectively. When the bonded sample was annealed above the glass transition temperature followed by cooling at 5℃/min cooling rate, the residual stress was reduced to 6MN/㎡.
MnZn Ferrite Preparation by Coprecipitation Method
Journal of the Korean Ceramic Society, volume 30, issue 6, 1993, Pages 478~484
The influence of reaction conditions on the MnZn ferrite coprecipitation process were investigated using mixed metla sulfate solution and ammonium oxalate. In order to minimize the metallic ion losses and to control the particle size, the optimum reaction conditions were as follows; reaction temperature
, metal sulfate concentration 0.3M, molar ratio of ammonium oxalate/mixed metal sulfate 1.1:1. The production yield was as high as 97.6% of theoretical yield at optimum reaction condition.
Control of Pore Characteristics of Porous Glass in the
System Prepared by the Sol-Gel Method
Journal of the Korean Ceramic Society, volume 30, issue 6, 1993, Pages 485~491
Porous glass in the ZrO2.SiO2 system containning up to 30mol% zirconia were prepared by the sol-gel method from metal alkoxides and their pore characteristics with reaction parameters were investigated. The gels were made by hydrolyzing and condensation of the mixed metla alkoxides and were converted into the porous glass by heating up to
. As a results, the mean pore radius became larger with increasing contents of HCl, H2O and hydrolysis temperature, and an alcohol with a large molecular weight for making the porous glass. In the case of 20ZrO2.80SiO2 porous glass with heated at
, HCl and H2O content was 0.3mol and 4mol, the specific surface area was 284
/g, average mean pore radius was about 19.4
, porosity was 22.55% and pore characteristics depended on heating temperature.
SiC-Whisker Dispersion and Mechanical Properties of
Journal of the Korean Ceramic Society, volume 30, issue 6, 1993, Pages 492~498
The pretreatment condition for uniform distribution of SiC whisker in A2O3-SiCw composites has been determined and the mechanical properties of the composites with various whisker contents have been measured. Good dispersion of the whisker can be obtained in a solution of pH=10.45 by ball milling and ultrasonic treatment. The relative density of hot pressed composites decreases with the whisker content up to 40vol%, but is found to be satisfactory, over 98% for all samples. The mechanical property of the composites is sensitive to the whisker dispersion. Uniform distributjion of the whisker is critical in order to guarantee good mechanical property.The samples containing 20~30vol% whisker show the best mechanical property within the studied range.
An XRD Study on the Structures of Ferrites : Hematite, Ba-ferrite and Zn2Y(Ba2Zn2Fe12O22)
Journal of the Korean Ceramic Society, volume 30, issue 6, 1993, Pages 499~509
Structures of hematite(
-Fe2O3), Ba-ferrite(BaFe12O19) and Zn2Y(Ba2Zn2Fe12O22) were studied by powder X-ray diffraction(XRD) method. Powder XRD patterns of the ferrites were analyzed with the Rietveld method, and the final refined R-factors were RWP<0.01 and RI<0.03. The lattice parameters refined with hexagonal crystal system were a=5.0342
for hematite, a=5.8928
for Ba-ferrite, and a=5.8763
for Zn2Y. In the hematite, the oxygen parameter is 0.3072 and the Fe-O distances in FeO6octahedron are 1.941
, close to the single crystal data of Blake et al.. In the Ba-ferrite, the Fe atom in oxygen trigonal bipyramid is displaced 0.155
away from the BaO3 mirror plane into 4e position. In the Zn2Y, 75% of Zn is located at the oxygen terahedral site in S-block.
Thin Films by Thermal Diffusion from Multilayrs
Journal of the Korean Ceramic Society, volume 30, issue 6, 1993, Pages 510~516
thin films have been formed by rapid thermal annealing(RTA) of
multilayer films deposited on Si wafers by RF sputtering. Based on the optimal depositon conditions of TiO2 and Pb,
three layers were deposited for 900
each. These films were subjected to RTA process at the temperatures ranging from
for 30 seconds in air, and were analyzed by X-ray diffraction and transmission electron microscopy to investigate the phases and the microstructures. As a result, perovskite
phases was obtained above
with the trace of unreacted
. RBS analysis revealed the anisotropic behavior of diffusion that the diffusivity of Pb to the bottom
layer was faster than that of Pb to the top
layer. The amorphous Pb-silicate was formed between film and Si substrate due to the diffusion of Pb, but Pb-silicate existed locally at the interface and the amount of that phase was very small. Therefore the effect of bottom
layer as a diffusion barrier was confirmed.
films formed by current technique showed a relative dielectric constant of 60, and the maximum breakdown field reached 170kV/cm.