| 摘要 |
The provided are a glass for a magnetic recording medium substrate permitting the realization of a magnetic recording medium substrate affording good chemical durability and having an extremely flat surface, a magnetic recording medium substrate comprised of this glass, a magnetic recording medium equipped with this substrate, and methods of manufacturing the same. Glasses for a magnetic recording medium substrate are, glass I comprised of an oxide glass, comprising, denoted as mass percentages: Si 20 to 40 percent, Al 0.1 to 10 percent, Li 0.1 to 5 percent, Na 0.1 to 10 percent, K 0 to 5 percent (where the total content of Li, Na, and K is 15 percent or less), Sn 0.005 to 0.6 percent, and Ce 0 to 1.2 percent;
the Sb content is 0 to 0.1 percent; and
not comprising As or F;
glass II comprised of oxide glass, comprising, as converted based on the oxide, denoted as molar percentages: SiO 2 60 to 75 percent, Al 2 O 3 1 to 15 percent, Li 2 O 0.1 to 20 percent, Na 2 O 0.1 to 15 percent, and K 2 O 0 to 5 percent
(where the total content of Li 2 O, Na 2 O, and K 2 O is 25 percent or lower);
based on the total amount of the glass components, 0.01 to 0.7 mass percent of Sn oxide and 0 to 1.4 mass percent of Ce oxide are added;
the content of Sb oxide is 0 to 0.1 mass percent; and
not comprising As or F; and
glass III comprised of oxide glass, comprising, converted based on the oxide, denoted as molar percentages: SiO 2 60 to 75 percent, Al 2 O 3 1 to 15 percent, Li 2 O 0.1 to 20 percent, Na 2 O 0.1 to 15 percent, K 2 O 0 to 5 percent
(where the total content of Li 2 O, Na 2 O, and K 2 O is 25 percent or less);
by comprising a 0.1 to 3.5 mass percent of total content of Sn oxide and Ce oxide, based on the total amount of the glass components;
the ratio of the Sn oxide content to the total content of Sn oxide and Ce oxide (Sn oxide content/(Sn oxide content + Ce oxide content)) is 0.01 to 0.99;
the Sb oxide content is 0 to 0.1 percent; and
comprising no As or F. |
