| 摘要 |
PROBLEM TO BE SOLVED: To provide a magnetic recording medium substrate glass improved in heat resistance and flattering characteristics.SOLUTION: The magnetic recording medium substrate glass includes SiOof 60-75%, AlOof 10-15%, BOof 7-12%, MgO of 0-15%, CaO of 3-15%, SrO of 0-10%, BaO of 0-10%, NaO of 0-10%, KO of 0-10%, LiO of 0-10%, TiOof 0-3% and ZrOof 0-1% by mol% on an oxide basis. The total content of the 12 components is 97% or more; the total content of MgO, CaO, SrO and BaO is 10-20%, and the total content of NaO, LiO and KO is 1-10%. The value of the product of a transverse vibration internal friction at a resonance vibration frequency of 3000 Hz and a specific modulus is 1.2×10MNm/kg or more.SELECTED DRAWING: Figure 1 |
