METHOD FOR PRODUCING GLASS SUBSTRATE FOR MAGNETIC DISK, AND MAGNETIC DISK

摘要

A METHOD FOR PRODUCING A GLASS SUBSTRATE FOR A MAGNETIC DISK BY POLISHING A CIRCULAR GLASS PLATE, WHICH COMPRISES A STEP OF POLISHING THE PRINCIPAL PLANE OF THE CIRCULAR GLASS PLATE BY USING A SLURRY CONTAINING A CEO2 CRYSTAL POWDER, THE CEO2 CRYSTAL POWDER BEING OBTAINED IN SUCH A MANNER THAT A MELT CONTAINING CE(2 IS QUENCHED TO OBTAIN AN AMORPHOUS MATERIAL, AND THE AMORPHOUS MATERIAL IS SUBJECTED TO HEAT TREATMENT TO OBTAIN A CEO2 CRYSTALS-PRECIPITATED AMORPHOUS MATERIAL, WHICH IS SUBJECTED TO ACID TREATMENT TO SEPARATE AND EXTRACT THE CEO2 CRYSTAL POWDER FROM THE CEO2 CRYSTALS-PRECIPITATED AMORPHOUS MATERIAL.