Journal of the Ceramic Association, Japan
Online ISSN : 1884-2127
Print ISSN : 0009-0255
ISSN-L : 0009-0255
Volume 74, Issue 856
Displaying 1-3 of 3 articles from this issue
  • Kazuo OOKA, Toru KISHII
    1966 Volume 74 Issue 856 Pages 363-366
    Published: December 01, 1966
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    As the first step to determine the kinds or the compositions of glasses that show the stress build up caused by ultra-violet irradiation, binary borate glasses containing respectively oxides of Li, Na, K, Ca, Sr, Ba, Cd, La, Bi, Pb, Tl, Si, and Zn, were prepared and subjected to ultra-violet irradiation. The irradiated surface layers of the glasses were examined photoelastically. Stress build-up was observed only in the glasses containing Li2O, Na2O and K2O. Possible mechanisms of the stress build-up and the behaviour of alkali ions or change of coordination number of B3+ ions were discussed.
    With alkali germanate glasses, although change of coordination number of Ge4+ ions seems possible with change of glass composition, stress buildup was not found by ultra-violet irradiation.
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  • Hideo TAGAI, Shinichi IWAI, Takayoshi ISEKI
    1966 Volume 74 Issue 856 Pages 366-371
    Published: December 01, 1966
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    The diffusion rate coefficients of iron oxide into single crystal of magnesia were investigated in the temperature range of 1300° to 1590°C and under the oxygen partial pressures of 10-9.0atm to 10-6.1atm. The concentration gradients of the diffused iron ion were analysed by using the electron probe X-ray microanalyser (XMA). The diffusion coefficient was 4.5×10-4 exp (-50, 000/RT)cm2/sec in the above atmosphere, while the value 1.3×10-3 exp (-49, 000/RT)cm2/sec in air.
    The quenching technique was applied in order to analyse the reaction between single crystal magnesia and iron oxide in such conditions. The specimen was instantly quenched in the reducing atmosphere bydropping it to the bottom of the furnace. The products analysed by X-ray oscillation method were as follows; at 1300°C, Po2=10-9.0atm magnesiowüstite, at 1380°C, Po2=10-8.2atm magnesiowüstite with a small amount of magnesioferrite, at 1490°C, Po2=10-7.1atm and at 1590°C, Po2=10-6.1atm magnesiowüstite and magnesioferrite. They were formed on the host crystal with a high order of topotactic relation.
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  • Hiroaki YANAGIDA, Goro YAMAGUCHI, Joe KUBOTA
    1966 Volume 74 Issue 856 Pages 371-378
    Published: December 01, 1966
    Released on J-STAGE: April 30, 2010
    JOURNAL FREE ACCESS
    Kinetics of alpha alumina formation from two types of transient alumina, gamma and theta, has been investigated considering the role of water vapor. The mechanism was of nucleation determinant. Water vapor facilitated nucleation of alpha alumina and lowered the activation energy for the process. Under the high vapor pressure of water, however, the fraction of alpha alumina was apparently saturated in the present work. Water vapor generated from the lattice of gamma alumina also behaved like a catalyzer for the nucleation process of alpha alumina. Crystallite size of transient alumina must be considered in order to clarify the nucleation process. The role of water vapor is essential in the rection of alpha alumina formation from transient alumina.
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