Patent ID: 7575615

Claim:
A process for preparing a polishing composition for a Ni—P plated aluminum alloy substrate comprising a colloidal silica prepared from a silicate, said composition being prepared by a method comprising the steps of: (1) adjusting the pH of a silica dispersion comprising colloidal silica, having an average particle size of primary particles of 1 nm or more and less than 40 nm, to a range of from 10 to 12 in order to increase a density of silanol groups formed on the surface of the colloidal silica; (2) re-adjusting the pH of the silica dispersion obtained in the step (1) to a range of from 1 to 4; and wherein the density of silanol groups is from 0.06 to 0.3 mmol per 1 g of the colloidal silica and said polishing composition has a pH of 1 to 4.