| 摘要 |
A method for polishing a magnetic disk substrate, comprising two polishing steps and an intermediate cleaning step, wherein during the first, rough polishing step a polishing liquid composition is used, which contains non-spherical silica particles A having ΔCV 0-10% and a particle size ratio D1/D2 2.00-4.00, where D1 is a volume average particle size determined by dynamic light scattering and D2 is a particle size converted from a BET specific surface area; spherical silica particles B, having a volume average particle size D1 of 6.0-80.0 nm; an acid, which is at least a phosphoric, phosphonic and/or organic phosphonic acid; an oxidising agent; and water, wherein the mass ratio of the silica particles (A/B) ranges from 80/20 to 99/1, and their total content (A+B) amounts to more than 98.0% wt of all the silica particles contained therein. Particles A may be spinous-shaped, heteromorphic (fig. 1) or combinations thereof. The pH of the liquid polish may be 0.5-6.0. A polishing liquid composition is also claimed, which additionally has the features of CV90 20.0-40.0% for particles A; CV90 10.0-35.0% and ΔCV 0-10% for particles B. The invention aims at reducing long cycle defects on the substrate, preferably a Ni-P-plated aluminium alloy substrate. |
