| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a glass ceramic substrate for magnetic information recording medium having the substrate surface excellent in ultra smoothness by forming the substrate from an SiO2 -Al2 O3 -Li2 O-based glass ceramic substrate having a main crystalline phase comprising at least one kind ofβ-quartz solid solution, or a mixed crystalline of theβ-quartz solid solution andβ-spodumene. SOLUTION: A glass raw material is melted at 1,450-1,500 deg.C, homogenized and thereafter formed into a disk-like molding material. The disk-like molding material is heat-treated at 650-750 deg.C to form crystalline nuclears and further heat-treated at 750-950 deg.C to crystallize and to provide an SiO2 -Al2 O3 -Li2 O-based glass ceramic having a main crystalline phase comprising at least one kind ofβ-quartz solid solution, or a mixed crystalline of theβ-quartz solid solution andβ-spodumene. A glass ceramic substrate for a magnetic information recording medium is obtained by lapping the ceramics with abrasive grains having 5-30μm average particle diameter, performing a grind-finishing treatment of the lapped ceramics with CeO2 having 0.2-2.0μm average diameter to form the ceramics having 1-5Åsurface roughness, further forming unevenness in a landing region by irradiating pulse laser rays on the ceramic substrate by an LD-excited solid laser, etc.</p> |
