摘要:
A method of producing a glass substrate for an inforamtion recordeing medium either by press-molding molten glass obtained from glass containing 0.1 to 30 mol.% of TiO2. 1 to 45 mol.% of CaO, 5 to 40 mol.% of the sum of MgO and CaO described above, 3 to 30 mol.% of the sum of Na2O and Li2O. 0 to 15 mol.% of Al2O3 and 35 to 65 mol.% of SiO2 and having a liquidus temperature of not higher than 1,360 °C, a viscosity of at least 10 poises within a moldable temperature range and a transition point temperature of lower than 700 °C, or by preparing a preform of glass containing 0.1 to 30 mol.% of TiO2, 1 to 45 mol.% of CaO, 5 to 40 mol.% of the sum of MgO and CaO described above, 3 to 30 mol.% of the sum of Na2O and Li2O, 0 to 15 mol.% of Al2O3 and 35 to 65 mol.% of SiO2 and having a liquidus temperature of not higher than 1,360 °C, and shaping the preform into a disk by re-heat pressing.
摘要:
Disclosed is a process for producing a glass substrate for an information recording medium by press-shaping a molten glass which gives a glass containing 0.1 to 30 mol% of TiO 2 , 1 to 45 mol% of CaO, 5 to 40 mol% of total of MgO and the above CaO, 3 to 30 mol% of total of Na 2 O and Li 2 O, 0 to 15 mol% of Al 2 O 3 and 35 to 65 mol% of SiO 2 and having properties of a liquidus temperature of 1,360°C or lower and a viscosity of at least 10 poise in a shaping-allowable temperature range, or by preparing a preform formed of a glass which contains 0.1 to 30 mol% of TiO 2 , 1 to 45 mol% of CaO, 5 to 40 mol% of total of MgO and the above CaO, 3 to 30 mol% of total of Na 2 O and Li 2 O, 0 to 15 mol% of Al 2 O 3 and 35 to 65 mol% of SiO 2 and has properties of a liquidus temperature of 1,360°C or lower and shaping the preform in the form of a disc by a re-heat pressing method. According to the above process, there can be mass-produced, with high productivity, high-quality glass substrates to be used for information recording media such as a magnetic disc, an optical disc, a magneto-optic disc, and the like.
摘要:
Disclosed is SiO 2 -Al 2 O 3 -RO (RO = divalent metal) glass having high specific elastic modulus of 36 x 10 6 Nm/kg or more or high Young's modulus of 110 GPa or more, high transition temperature of 700°C or higher (high heat resistance). The glass exhibits excellent surface smoothness (surface roughness Ra