| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a glass substrate for magnetic recording medium having no work-affected layers such as a scratch on an end surface including a chamfer part on its glass substrate, being polished on the end surface at high polishing speed while suppressing the use of cerium oxide abrasive grains thereon as much as possible. <P>SOLUTION: A glass substrate for magnetic recording medium having in its disc-shaped glass substrate a through-hole at the center part, an inner peripheral side surface constituting the through-hole, an outer peripheral side surface, and a pair of main plain surfaces facing to each other. In intersection parts between the main plain surfaces, and the inner peripheral side surface and the outer peripheral side surface, an inner peripheral chamfer part and an outer peripheral chamfer part are formed, respectively. At least one of the inner peripheral chamfer part and the outer peripheral chamfer part has a diameter or the longest diameter of a major axis of 10 μm or more, and has the number of pit defects of 5/mm<SP POS="POST">2</SP>or less, being evaluated after an etching of 5 μm on the surface of the glass substrate. <P>COPYRIGHT: (C)2013,JPO&INPIT |
