| 摘要 |
PURPOSE:To readily obtain the title substrate holding a high-density recording medium by crystallization treatment of a specific crystal glass-contg. substrate followed by abrasion and by treatment with an etchant with etching rate for crystal layer differing from that for amorphous one. CONSTITUTION:A substrate containing SiO2-Li2O-Al2O3 based crystallized glass is put to crystallization treatment followed by abrasion and then treatment with an etchant with etching rate for crystal layer differing from that for amorphous one, thus obtaining the objective recording disk substrate. For said crystallized glass, its surface has been abrasion-treated and its fine structure is such that fine, homogeneous crystal grains are regularly, uniformly and two- dimensionally distributed in the amorphous layer. As the surface of the present substrate has the fine structure, an air turbulence is produced on the surface by the rotation of the disk substrate, acting as a buoyant resistance against a magnetic head. Thereby the magnetic head will keep at a aluminum distance from the substrate surface without causing any magnetic head crush. |
