| 摘要 |
PROBLEM TO BE SOLVED: To improve the specific Young's modulus of glass and also to increase the productivity of a glass substrate by specifying composition ratios of SiO2, Al2O3, MgO and ZrO2 being main components. SOLUTION: The composition range of main components are kept in 47.5-58% SiO2, 10-30% Al2O3, 10-30% MgO and 0.1-2.8% ZrO2 by weight ratio. When SiO2 is less than 47.5%, melt property becomes worse, and when SiO2 is more than 58%, crystal is hardly precipitated. Then Al2O3 is less than 10%, a precipitated crystal is small and strength is low, and when Al2O3 is more than 30%, melt temp. becomes high and the glass is liable to devitrify. When MgO is less than 10%, the chemical durability of a glass matrix phase is not improved, and when MgO is more than 30%, other crystalline phase is precipitated and desired strength is difficult to obtain. When ZrO2 is less than 0.1%, sufficient crystalline nucleus is hardly formed and fine and homogeneous crystalline structure is not obtained. Also when ZrO2 is more than 2.8%, melt temp. becomes high and also the glass is liable to devitrify and melt formation becomes difficult.
|
