Invention Grant
US08168313B2 Glass for information recording medium substrate, glass substrate for information recording medium and magnetic disk 有权
用于信息记录介质基板的玻璃,用于信息记录介质的玻璃基板和磁盘

Glass for information recording medium substrate, glass substrate for information recording medium and magnetic disk
Abstract:
A glass for an information recording medium substrate, which comprises, as represented by mol % based on the following oxides, from 61 to 72% of SiO2, from 3 to 11% of Al2O3, from 0 to 14.3% of Li2O, from 0 to 22% of Na2O, from 0 to 22% of K2O, from 4 to 13% of MgO, from 0 to 6% of TiO2 and from 0 to 5% of ZrO2, provided that the total content of Li2O, Na2O and K2O (R2O) is from 10 to 22%, and (a) the ratio of the content of Li2O to R2O (Li2O/R2O) is at most 0.52, (b) the ratio of the content of Na2O to R2O (Na2O/R2O) is at least 0.35, or (c) the ratio of the content of K2O to R2O (K2O/R2O) is at least 0.45.
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