| 摘要 |
PURPOSE: Process for glass ceramic substrate for magnetic information memorizing medium is characterized by; main crystalline being not less than one selected from alpha-SiO2, alpha-SiO2, solid solution, alpha-cristobalite,alpha-cristobalite solid solution and Li2Si2O5; heat inflation coefficient at 50-70°C being +65 - +130 X 10¬-7/°C; surface illuminance of 3-9 angstrom. CONSTITUTION: Sio2-Li2O-K2O-MgO-ZnO-P2O5-Al2O3-ZrO2 based glass not including Na2O, PBO and characterized by containing each ingredient as following scope; 70-80wt% of SiO2, 9-12wt%, of LiO2, 2-5wt% of K2O, 0.5-4.8wt% of MgO, 0.2-3wt% of ZnO, 1.5-3wt%of P2O5 0.5-5wt% of ZrO; the ceramic substrate(1) obtained by heating for 1-12hrs at 450-550°C for nucleus forming, followed by reheating for 1-12hrs at 680-800°C and grinding at surface illuminance of 3-9 angstrom; the ceramic substrate(1) with data field(2) and landing field(3) having many unevenness or projection formed by CO2 laser inspection; on the ceramic substrate, magnetic disk is formed as undercoat layer, meddle layer, protection layer and lubrication layer.
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