| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that there is no glass composition suited for being formed into sheet glass by a float process, having a coefficient of thermal expansion and viscosity characteristics suitable to facilitate thermally reinforcement, and having a distortion point and a softening point higher than those of soda lime glass so as to be desirable for heat-resistant glass, especially heat-resistant fireproof glass or various substrate glasses. SOLUTION: A glass composition is provided which is substantially free from BaO and B<SB>2</SB>O<SB>3</SB>and includes, as expressed in terms of mass%, 60-70 SiO<SB>2</SB>, 0.5-3.0 Al<SB>2</SB>O<SB>3</SB>, 2-8 Na<SB>2</SB>O, 5-15 K<SB>2</SB>O, 8-18 Na<SB>2</SB>O+K<SB>2</SB>O, 8-13 MgO, 0-5 CaO, 0-8 SrO, 10-22 each of MgO, CaO, and SrO, and 0.5-5 ZrO<SB>2</SB>. COPYRIGHT: (C)2009,JPO&INPIT
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