Journal of the Ceramic Association, Japan
Online ISSN : 1884-2127
Print ISSN : 0009-0255
ISSN-L : 0009-0255
Volume 84, Issue 971
Displaying 1-9 of 9 articles from this issue
  • Akira YAMAGUCHI, Etsuro KATO
    1976 Volume 84 Issue 971 Pages 307-313
    Published: July 01, 1976
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Magnesite refractories reacted with SO3 gas to form MgSO4 as solid phase. When Na2SO4 existed, however, the MgSO4 reacted with Na2SO4 to form liquid at above 670°C. Over the range of 670°C to 814°C, Na2SO4⋅3MgSO4 crystallized from liquid with proceeding of the reaction, but at above 814°C, did not. As a result of formation of liquid, the amount of SO3 picked up by the refractories increased particularly at 814°C to 1000°C and was maximum about 1000°C, but at above the temperature it decreased. Liquid formed by the reaction was transformed into Na2SO4⋅3MgSO4 and MgSO4 during cooling.
    When K2SO4 existed, reaction of the refractories with SO3 gas was similar to the reaction in the case of existing of Na2SO4. Over the range 884°C to 1000°C the amount of SO3 picked up by the refractories was particularly increased and liquid formed by the reaction was transformed into K2SO4⋅2MgSO4 and MgSO4 during cooling.
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  • Takeshi HOSHIKAWA
    1976 Volume 84 Issue 971 Pages 313-320
    Published: July 01, 1976
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    The noncrystalline materials of the system SiO2-Al2O3-K2O were heat-treated at 1200°C-1600°C, and the inversion temperature of tetragonal→←cubic phases, the lattice constants and the amount of leucite crystals precipitated in the noncrystalline materials were measured by using DTA apparatus and X-ray diffractometer.
    It was found that the inversion temperature varied in the wide rage of 404°C to 628°C with the atomic ratio δ=Si/Si+Al+K of the noncrystalline material and the crystallization temperature. Each leucite precipitated in the noncrystalline materials with δ<0.5 showed a constant inversion temperature 621±7°C corresponding to that of the leucite with stoichiometric composition. Inversion temperature of leucite precipitated in the noncrystalline materials with δ>0.5 lowered with the increase of δ and with the decrease of crystallization temperature and the lattice parameter c/a tend to decrease with inversion temperature.
    It was concluded that in the case of δ>0.5, the leucite crystals having the composition of (KAl)1-xSi2+xO6 (x>0) had a higher symmetrical lattice than the stoichiometric one and the lattice defects which might be caused by the defficiencies of potassium ions increasing with δ.
    The shift of AlKα peak of the leucite crystals prepared was also measured by the X-ray fluorecence spectrometer. The results indicated that the aluminum ions in the leucite crystals were in fourfold coordination.
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  • Tomozo NISHIKAWA, Toshihiko NISHIDA, Nobuki HIRAI, Yasunori OKAMOTO
    1976 Volume 84 Issue 971 Pages 320-325
    Published: July 01, 1976
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Polycrystalline Ni0.5Zn0.5Fe2O4 was deformed under the bending stress of 11kg/cm2⋅min from room temperature to 1400°C. Below 600°C, the fracture of polycystals was completely brittle and the fractured surface was mostly transgranular. In the temperature range between 800°C and 1300°C, the relative contribution of intergranular failure increased with increasing temperature. The temperature at which the intergranular failure increased coincided with that at which internal friction of grain boundary increased. The brittle-ductile transition temperature under bending stress was about 1200°C, the same as the transition temperature under compressing stress. Above 1350°C, the fracture stress decreased rapidly with increasing temperature, and the fracture stress under bending stress was the same as that under compressing stress, and the fracture was entirely intergranular.
    Grain boundary slip was not large enough to be detected by the off-set of the marker line. Grain boundary was too brittle to slip at low temperatures, and was so plastic above 1350°C that it easily migrated and corrugated preventing the boundary slip. Only in the intermediate temperature range around 1300°C, slight grain boundary slip was observed by the off-sef of the marker line.
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  • Masahiko NAKAMURA, Susumu OKUDA
    1976 Volume 84 Issue 971 Pages 325-332
    Published: July 01, 1976
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    The resistivity against frost action in ceramics has usually been examined by freezing and thawing under three dimensional-cooling. But, it seems to be reasonable to examine under one dimensional-cooling, because structural materials are generally exposed under such a condition of one dimensional-cooling. Standing on this point of view, it was aimed to compare the appearances of frost damages caused under three dimensional- and one dimensional-cooling.
    As the results of investigation on an insulator brick, a roofing tile body, a wall tile and an earthenware body, several differences in the nature of frost damages between the two cooling methods have been elucidated as follows:
    (1) Provided that there is no directional difference in strength resulting from lamination and/or preferred orientation of particles in ceramic bodies, stratified cracks perpendicular to the cooling direction are developed under one directional-cooling, while under three dimensional-cooling non-stratified, random cracks are formed.
    (2) The stratified cracks stem plausibly from the preferred growth of ice along the cooling direction. This thought is strongly supported by the preferred expansion along the cooling direction observed on a model system in which thin glass plates are stacked together holding water films between them.
    (3) Under one dimensional-cooling the lower the rate of cooling the more severe damages occurs, while under three dimensional-cooling the higher rate of cooling causes the more severe damages.
    (4) Regardless of the two cooling methods, cracks develop along the direction of lower bonding strength in ceramic materials resulting from, if any, lamination and/or particle orientation.
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  • Teizo HASE, Hiroshige SUZUKI
    1976 Volume 84 Issue 971 Pages 332-337
    Published: July 01, 1976
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Reaction-sintered bodies of β-SiC were prepared in vacuum by impregnation of gaseous or liquid silicon into the following powder compacts; non-graphitizable carbon, artificial graphite and colloidal graphite. Microstructure of the resulting reaction-sintered bodies were observed with electron microscope and reflected optical microscope, and then it was found that the microstructure of reaction-sintered body by gaseous silicon differed greatly from that of reaction-sintered body by liquid silicon. The microstructure of the former could be explained on the basis of multi-grain-coalescence model which was previously proposed by the authors, while the microstructure of the latter was resulted from a predominant action of liquid silicon in the solution-precipitation mechanism.
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  • Hiroaki YANAGIDA, Takayoshi KANDACHI
    1976 Volume 84 Issue 971 Pages 338-341
    Published: July 01, 1976
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Voltage-current-time characteristic of stabilized zirconia with point contact platinum electrode was investigated in the temperature range of 480-650°C under Ar gas ambient. The applied voltage was chosen higher than 20 volts to give rise to deep polarization across the specimen. The current-time characteristic consisted of three stages. In the first stage of the characteristic the current increased slowly. Colored part gradually developed from cathode to anode. In this stage the ionic current predominated over the electronic current. The point at which the front of the colored part reached the anode was a transition to the second stage of characteristic, in which the rate of current increase was proportional to the current itself, where the current was of electronic behavior. Electrons thus injected were of the mobility by the order of 2×10-6cm2/V⋅sec at 580°C indicating hopping mechanism. Finally the breakdown took place. The color arose from injection of electrons from cathode.
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  • Masao MIZUNO, Alain ROUANET, Toyoaki YAMADA, Tetsuo NOGUCHI
    1976 Volume 84 Issue 971 Pages 342-348
    Published: July 01, 1976
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
  • Yusuke MORIYOSHI, Wazo KOMATSU
    1976 Volume 84 Issue 971 Pages 348-349
    Published: July 01, 1976
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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  • 1976 Volume 84 Issue 971 Pages A41-A48
    Published: July 01, 1976
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
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