| 摘要 |
<p>The present invention relates to an alkali-free glass having a strain point of 735°C or higher, an average thermal expansion coefficient at from 50 to 350°C of from 30×10 -7 to 40×10 -7 /°C, a temperature T 2 at which a glass viscosity is 10 2 dPa·s of 1,710°C or lower, a temperature T 4 at which a glass viscosity is 10 4 dPa·s of 1,340°C or lower, and a devitrification temperature of 1,330°C or lower, the alkali-free glass including, in terms of mol% on the basis of oxides: SiO 2 66 to 69, Al 2 O 3 12 to 15, B 2 O 3 0 to 1.5, MgO 6 to 9.5, CaO 7 to 9, SrO 0.5 to 3, BaO 0 to 1, and ZrO 2 0 to 2, in which MgO+CaO+SrO+BaO is from 16 to 18.2, MgO/(MgO+CaO+SrO+BaO) is 0.35 or more, MgO/(MgO+CaO) is 0.40 or more and less than 0.52, and MgO/(MgO+SrO) is 0.45 or more.</p> |
