| 摘要 |
PROBLEM TO BE SOLVED: To obtain a glass ceramic substrate for magnetic information recording media, having a good surface characteristic corresponding to the magnetic information recording media having high recording densities by using one or more of lithium disilicate, quartz, quartz solid solution, cristobalite, and cristobalite solid solution as a main crystal phase and specifying a thermal expansion coefficient at a specific temperature, a Young's modulus, a Vickers hardness, a specific gravity, a surface roughness after polished, and an Al2O3 content. SOLUTION: The main crystal phase comprises lithium disilicate (Li2O.2SiO2, the surface distance of the largest peak strength in X-ray diffraction method: d = 3.57 to 3.62Å), quartz (SiO2, d=3.33 to 3.41Å), quartz solid solution, cristobalite (SiO2, d=4.04 to 4.14Å), and/or cristobalite solid solution. The thermal expansion coefficient is +62 to +130×10-7/ deg.C. The Young's modulus is 80-150 GPa. The Vickers hardness is 4.5-15.0 GPa. The specific gravity is 2.2-2.8. The surface roughness (Ra) after polished is 3-9Å. The content of Al2O3 is 2 to <10%. The glass ceramic substrate enables the stable flotation of magnetic heads.
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