| Budget Amount *help |
¥7,400,000 (Direct Cost: ¥7,400,000)
Fiscal Year 1996: ¥7,400,000 (Direct Cost: ¥7,400,000)
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| Research Abstract |
{Purpose} Basic studies were made on refining process and stable controlling of redox state of commercial glasses doped with plural variable-valence ions with respect to color-controlling, efficient use of refining reagents, and suppression of SO_2 and CO_2 exhaustion from glass-melting furnaces. As an important example of such glasses, those doped with both Fe^<2+> ions acting as an infrared-ray absorber and Ce^<3+> ions as an ultraviolet-ray absorber were investigated.
{Experimentals} Glass samples were prepared by melting raw materials having molar compositions 16Na_2O・10CaO・74SiO_2 : Fe_2O_3, Ce_2O_3, Na_2SO_4. Sampling from glass melts was made at 1300ﾟC,that is, at temperature where melting reactions have roughly finished and refining reactions do not begin yet. While sampled glasses were remelted in "an high-purity-atmosphere furnace with optical windows" at atmosphere pressure of 1,10,32, or 100 kPa up to 1450ﾟC,formation and bursts of bubbles were recorded by a video camera and recorder (The furnace was custom-made for the present studies).
{Results} (A) Evolved gas analysis by quadrupole mass spectrometry on glass melts revealed details of reactions (1) - (3) during refining and cooling process.
Na_2SO_4*Na_2O+SO_2+1/2O_2 (1), Ce_2O_3+1/2O_2 (g) *2CeO_2 (2), Fe^<2+>+Ce^<4+>*Ce^<3+>+Fe^<3+> (3)
(B) Peaks in amount distribution of bursting bubbles shift from 1400ﾟC to 1270ﾟC as atmosphere pressures decrease from 100 kPa to 32 kPa, and the amount increases as the pressure decreases from 32 kPa to 10 kPa without distinguishable peak shift. Such observations will be useful for developing innovative industrial subatmospheric melting technologies.
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