Abstract: A polishing composition includes fumed alumina, alumina other than fumed alumina, colloidal silica, a first organic acid, a second organic acid, an oxidizing agent, and water. When the second organic acid is citric acid, the first organic acid is preferably malic acid, while when the second organic acid is malic acid, the first organic acid is preferably citric acid. When the second organic acid is succinic acid, iminodiacetic acid, itaconic acid, maleic acid, malonic acid, crotonic acid, gluconic acid, glycolic acid, lactic acid, or mandelic acid, the first organic acid is preferably either citric acid or malic acid. The polishing composition can be suitably used for polishing the surface of a substrate for a magnetic disk.

Abstract: A polishing composition of the present invention contains silicon dioxide, an acid, and water. Silicon dioxide is, for example, colloidal silica, fumed silica, or precipitated silica. The acid is, for example, hydrochloric acid, phosphoric acid, sulfuric acid, phosphonic acid, nitric acid, phosphinic acid, boric acid, acetic acid, itaconic acid, succinic acid, tartaric acid, citric acid, maleic acid, glycolic acid, malonic acid, methanesulfonic acid, formic acid, malic acid, gluconic acid, alanine, glycin, lactic acid, hydroxyethylidene diphosphonic acid, nitrilotris(methylene phosphonic acid), or phosphonobutane tricarboxylic acid. The pH of the polishing composition is preferably in the range of 0.5 to 6. The polishing composition can be suitably used in applications for polishing a glass substrate.

Abstract: A polishing composition contains silicon dioxide, an alkaline compound, and water. Silicon dioxide is, for example, colloidal silica, fumed silica, or precipitated silica. The alkaline compound is, for example, ammonium carbonate, potassium carbonate, sodium carbonate, ammonium hydrogen carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate, ammonium phosphate, potassium phosphate, sodium phosphate, ammonium hydrogen phosphate, potassium hydrogen phosphate, or sodium hydrogen phosphate. The polishing composition can be suitably used in applications for polishing a glass substrate.

Abstract: A polishing composition contains silicon dioxide, an alkaline compound, and water. Silicon dioxide is, for example, colloidal silica, fumed silica, or precipitated silica. The alkaline compound is, for example, ammonium carbonate, potassium carbonate, sodium carbonate, ammonium hydrogen carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate, ammonium phosphate, potassium phosphate, sodium phosphate, ammonium hydrogen phosphate, potassium hydrogen phosphate, or sodium hydrogen phosphate. The polishing composition can be suitably used in applications for polishing a glass substrate.

Abstract: A polishing composition includes fumed alumina, alumina other than fumed alumina, colloidal silica, a first organic acid, a second organic acid, an oxidizing agent, and water. When the second organic acid is citric acid, the first organic acid is preferably malic acid, while when the second organic acid is malic acid, the first organic acid is preferably citric acid. When the second organic acid is succinic acid, iminodiacetic acid, itaconic acid, maleic acid, malonic acid, crotonic acid, gluconic acid, glycolic acid, lactic acid, or mandelic acid, the first organic acid is preferably either citric acid or malic acid. The polishing composition can be suitably used for polishing the surface of a substrate for a magnetic disk.

Abstract: A polishing composition of the present invention contains silicon dioxide, an acid, and water. Silicon dioxide is, for example, colloidal silica, fumed silica, or precipitated silica. The acid is, for example, hydrochloric acid, phosphoric acid, sulfuric acid, phosphonic acid, nitric acid, phosphinic acid, boric acid, acetic acid, itaconic acid, succinic acid, tartaric acid, citric acid, maleic acid, glycolic acid, malonic acid, methanesulfonic acid, formic acid, malic acid, gluconic acid, alanine, glycin, lactic acid, hydroxyethylidene diphosphonic acid, nitrilotris(methylene phosphonic acid), or phosphonobutane tricarboxylic acid. The pH of the polishing composition is preferably in the range of 0.5 to 6. The polishing composition can be suitably used in applications for polishing a glass substrate.

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.

Abstract: A polishing composition for a memory hard disc, which comprises the following components (a) to (d):(a) water,(b) at least one compound selected from the group consisting of a polystyrenesulfonic acid, and its salts,(c) a compound selected from the group consisting of an inorganic acid and an organic acid, and their salts, other than component (b), and(d) at least one abrasive selected from the group consisting of aluminum oxide, silicon dioxide, cerium oxide, zirconium oxide, titanium oxide, silicon nitride and manganese dioxide.

Abstract: A polishing composition for memory hard discs used to obtain polished surfaces of a high precision and a high quality with a high stock removal rate. The composition consists of water, alumina polishing agent, and polishing accelerator, and polishes surfaces of alumite, aluminum, and non-electrolytically nickel plated memory hard discs. The polishing accelerator is one kind selected from the group of molybdate of ammonium molybdate, lithium molybdate, sodium molybdate and potassium molybdate, or a kind selected from the group of molybdate and aluminum salt such as aluminum nitrate or aluminum oxalate, or another one kind selected from the group of molybdate and nickel sulfate, nickel nitrate, nickel sulfamate, and nickel acetate. The addition quantity of the substance above is 0.1 to 20%, the weight ratio of the polishing agent is 2 to 30%, and the mean particle diameter is 0.3 to 10 .mu.m.