Abstract: A polishing composition comprising an abrasive, an anticorrosive, an oxidizing agent, an acid, a pH regulator and water and having a pH within a range of from 2 to 5, wherein the abrasive is colloidal silica or fumed silica, and its primary particle size is at most 20 nm.

Abstract: A polishing composition for a memory hard disk, which comprises at least the following components (a) to (d): (a) from 0.1 to 50 wt %, based on the total amount of the polishing composition, of at least one abrasive selected from the group consisting of silicon dioxide, aluminum oxide, cerium oxide, zirconium oxide, titanium oxide, silicon nitride and manganese dioxide, (b) from 0.001 to 10 wt %, based on the total amount of the polishing composition, of at least one periodate selected from the group consisting of periodic acid, potassium periodate, sodium periodate and lithium periodate, (c) a buffer component to adjust the pH of the polishing composition to a range of from 2 to 5, and (d) water.

Abstract: A polishing composition for a memory hard disk, which comprises at least the following components (a) to (d): (a) from 0.1 to 50 wt %, based on the total amount of the polishing composition, of at least one abrasive selected from the group consisting of silicon dioxide, aluminum oxide, cerium oxide, zirconium oxide, titanium oxide, silicon nitride and manganese dioxide, (b) from 0.001 to 10 wt %, based on the total amount of the polishing composition, of at least one periodate selected from the group consisting of periodic acid, potassium periodate, sodium periodate and lithium periodate, (c) from 0.01 to 30 wt %, based on the total amount of the polishing composition, of at least one peroxydisulfate salt selected from the group consisting of ammonium peroxydisulfate, potassium peroxydisulfate and sodium peroxydisulfate, and (d) water, and which has a pH of from 2 to 7.

Abstract: A polishing composition for a memory hard disk, which comprises the following components (a) to (d): (a) from 0.1 to 50 wt %, based on the total amount of the polishing composition, of at least one abrasive selected from the group consisting of silicon dioxide, aluminum oxide, cerium oxide, zirconium oxide, titanium oxide, silicon nitride and manganese dioxide, (b) from 0.001 to 10 wt %, based on the total amount of the polishing composition, of at least one iron salt selected from the group consisting of iron nitrate, iron sulfate, ammonium iron sulfate, iron perchlorate, iron chloride, iron citrate, ammonium iron titrate, iron oxalate, ammonium iron oxalate and an iron chelate complex salt of ethylenediaminetetraacetic acid, (c) from 0.01 to 30 wt %, based on the total amount of the polishing composition, of at least one peroxydisulfate salt selected from the group consisting of ammonium peroxydisulfate, potassium peroxydisulfate and sodium peroxydisulfate, and (d) water.

Abstract: A polishing composition for polishing a memory hard disk, which comprises the following components (a) to (d): (a) from 0.1 to 50 wt %, based on the total amount of the polishing composition, of at least one abrasive selected from the group consisting of silicon dioxide, aluminum oxide, cerium oxide, zirconium oxide, titanium oxide, silicon nitride and manganese dioxide, (b) from 0.0001 to 3.0 wt %, based on the total amount of the polishing composition, of at least one polishing resistance-reducing agent selected from the group consisting of a surfactant, a water-soluble polymer and a polyelectrolyte, (c) from 0.001 to 40 wt %, based on the total amount of the polishing composition, of at least one polishing accelerator selected from the group consisting of an inorganic acid, an organic acid and their aluminum, iron, nickel and cobalt salts, and (d) water.