Patent ID: 7780504

Claim:
A method for manufacturing a magnetic recording medium disk substrate, comprising a step of texturing a NiP surface of the substrate, the step of texturing the NiP surface is conducted by pressing a polishing tape by a pressing means against the NiP disk substrate surface rotated in a circumferential direction by a rotating means, while supplying a slurry containing abrasive grains, including cluster diamonds formed by bonding a plurality of primary single-crystal nano-diamond particles together in a dispersing medium, to the NiP surface of the disk substrate to form a texture in the NiP surface, wherein the polishing tape consists essentially of monofilament polyester fiber having a fiber diameter 400 nm or more and 950 nm or less, on at least a surface which contacts the NiP surface of disk substrate during the texturing, and wherein secondary particles of the cluster diamond have an average particle diameter of 50 nm or more and 300 nm or less.