GLASS SUBSTRATE FINISH-POLISHING METHOD, AND ALKALI-FREE GLASS SUBSTRATE FINISH-POLISHED ACCORDING TO SAID METHOD

摘要

the present invention is a glass with a polishing slurry containing cerium oxide as abrasive grains polishing the main surface of the substrate, as a finish polishing process of the glass substrate, and a composition for an alkali-free glass of the glass substrate, the height of the curvature in terms of the curvature of the pitch of the main surface of the glass substrate 20 0.10 in 0.14 When called by the X ( ) polishing amount of the glass substrate at the time of change, 0.04 / X comprising the step of grinding is at least 0.12 on the condition that a, to a finish polishing process of the glass substrate: the strain point 710 The , the average thermal expansion coefficient in a 50 to 350 30 10 ^-7 to 43 10 ^-7 / , and the glass viscosity of 10 ² d s, and temperatures T ₂ is less than that in 1710 , the glass viscosity of 10 ⁴ d s temperature to be T ₄ is less than 1320 , SiO in oxide-based mole% of the display ₂ : 66 to 70, Al ₂ O ₃ : 12 to 15, B ₂ O ₃ : 0 to 1.5, MgO: 9.5 or less than 13, CaO: 4 to 9, SrO: 0.5 to 4.5, BaO: 0 to 1, ZrO ₂ : 0 to contain 2, and MgO + CaO + SrO + BaO is 17 to 21, and the MgO / (MgO + CaO + SrO + BaO) is at least 0.40, MgO / (MgO + CaO) is not less than 0.40, MgO / (MgO + SrO). The alkali-free glass is less than 0.60 ;