| 摘要 |
The present invention provides a glass plate to be tempered, which has a low thermal expansion coefficient, a high surface compression stress due to physical reinforcements and a low density and is excellent in the scratch durability. A glass plate to be tempered which comprises, by mass% as represented by the following composition:
SiO 2 : €ƒ€ƒ€ƒ55 to 85%,
B 2 O 3 : €ƒ€ƒ€ƒ2 to 12%,
MgO: €ƒ€ƒ€ƒ0.1 to 12%,
CaO: €ƒ€ƒ€ƒ0.1 to 12%,
Na 2 O: €ƒ€ƒ€ƒ0 to 13%,
MgO+CaO+SrO+ZnO: €ƒ€ƒ€ƒ3 to 16% and
Al 2 O 3 : €ƒ€ƒ€ƒ0 to 3% and,
which can be tempered by heating and quenching. |
