| 摘要 |
PROBLEM TO BE SOLVED: To provide a flat float glass which (1) is free from surface defects caused in floating by the interaction between molten glass and molten metal and obstructive to the use of the glass (2) is produced with a high light transmittance without unscheduled coloring, (3) has high temperature stability after thermal prestressing, (4) has needed seed quality (a small number of bubbles) without using an ordinary refining agent such as arsenic oxide and/or antimony oxide, (5) retains high surface quality in transition to a crystal phase, becomes a glass-ceramic having a very low coefficient of thermal expansion, (6) is transparent with a high light transmittance, translucent or opaque in various concrete examples and can be colored by adding a coloring component. SOLUTION: The flat float glass is convertible to glass-ceramic having a high quartz mixed crystal or a keatite mixed crystal and the concentrations of Pt, Rh, ZbO and SnO2 in the glass are <300 ppb, <30 ppb, <1/5 wt.% and <1 wt.%, respectively.
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