Manufacturing method of glass substrate for magnetic disk, magnetic disk, and magnetic data recording/reproducing device

Abstract

A manufacturing method of a glass substrate for a magnetic disk is provided whereby nano pits and/or nano scratches cannot be easily produced in polishing a principal face of a glass substrate using a slurry containing zirconium oxide as an abrasive. The manufacturing method of a glass substrate for a magnetic disk includes, for instance, a polishing step of polishing a principal face of a glass substrate using a slurry containing, as an abrasive, zirconium oxide abrasive grains having monoclinic crystalline structures (M) and tetragonal crystalline structures (T).

What is claimed is: 
     
         1 . A manufacturing method of a glass substrate for a magnetic disk, comprising:
 a polishing step of executing polishing using a slurry containing yttrium-contained partially stabilized zirconia as an abrasive.   
     
     
         2 . The manufacturing method of a glass substrate for a magnetic disk recited in  claim 1 , wherein the abrasive contains yttrium in a range of 1 to 6% by mole. 
     
     
         3 . The manufacturing method of a glass substrate for a magnetic disk recited in  claim 1 , wherein the abrasive contains yttrium oxide in a range of 1 to 6% by mole. 
     
     
         4 . The manufacturing method of a glass substrate for a magnetic disk recited in  claim 1 , wherein the glass substrate is made of glass, the glass having the fracture toughness value in a range of 0.4 to 1.5 MPa·m 1/2 . 
     
     
         5 . The manufacturing method of a glass substrate for a magnetic disk recited in  claim 1 , further comprising:
 a post polishing step of polishing using a slurry containing colloidal silica as abrasive grains, the post polishing step configured to be executed after the polishing step.   
     
     
         6 . The manufacturing method of a glass substrate for a magnetic disk recited in  claim 5 , wherein a removal stock is set to be less than or equal to 5 μm in the post polishing step. 
     
     
         7 . The manufacturing method of a glass substrate for a magnetic disk recited in  claim 5 , further comprising:
 an intermediate polishing step of polishing using a slurry containing cerium oxide abrasive grains, the intermediate polishing step being executed between the polishing step and the post polishing step.   
     
     
         8 . The manufacturing method of a glass substrate for a magnetic disk recited in  claim 5 , further comprising:
 a chemically strengthening step configured to be executed between the polishing step and the post polishing step.   
     
     
         9 . A magnetic disk made of a glass substrate manufactured with the method recited in  claim 1 , wherein at least a magnetic layer is formed on a principal face of the glass substrate. 
     
     
         10 . A magnetic recording/reproducing device, comprising:
 the magnetic disk recited in  claim 9 ; and   a magnetic head embedded with a DFH (Dynamic Flying Height) control mechanism.