| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a glass substrate which is used for a magnetic disk, has the flatness secured by reducing even ultra minute projections to lessen the surface roughness and can cope with high density recording by making the floating height of a magnetic head smaller in a magnetic disk device, and to provide a method for manufacturing the glass substrate for the magnetic disk. SOLUTION: This method for manufacturing the glass substrate for the magnetic disk comprises a step to form the glass substrate from a glass starting material, a step to grind the surface of the glass substrate and a step to temper the ground glass substrate chemically by ion exchange by immersing it in molten salt. In the grinding step an abrasive containing 60 mass % or more cerium oxide is used so that the glass substrate after the chemical tempering treatment has 0.5 nm or smaller arithmetic average surface roughness Ra, 0.6 nm or smaller root-mean-average roughness RMS and 0.5 nm or smaller minute waviness WA. The grinding step may comprise a step to grind it by using the solution containing the abrasive and a step to grind it by using the solution containing no abrasives.</p> |
