Abstract: A polishing composition for a hard disk substrate includes alumina particles, silica particles, and water. The volume median diameter of secondary particles of the alumina particles measured by a laser beam diffraction method is 0.1 to 0.8 ?m. The volume median diameter of primary particles of the silica particles measured by transmission electron microscope observation is 40 to 150 nm. The standard deviation in number-basis particle size of the primary particles of the silica particles measured by the transmission electron microscope observation is 11 to 35 nm. The polishing composition for a hard disk substrate can preferably reduce the embedding of alumina abrasive grains into the substrate without impairing the productivity.

Abstract: The present invention preferably provides a polishing composition for a hard disk substrate, containing aluminum oxide particles and water, wherein secondary particles of the aluminum oxide particles have a volume-median particle size of from 0.1 to 0.7 ?m, and particles having particle sizes of 1 ?m or more of the aluminum oxide particles are contained in an amount of 0.2% by weight or less of the polishing composition; and a method for manufacturing a hard disk substrate using the polishing composition. By using the polishing composition and the method for manufacturing a substrate of the present invention, for example, a hard disk substrate suitable for high recording density can be provided in high productivity.

Abstract: A polishing composition containing an abrasive and water, wherein the polishing composition has a pH of from 0.1 to 7, and satisfies the following conditions: (1) that the number of polishing particles having sizes of 0.56 ?m or more and less than 1 ?m is 500,000 or less per 1 cm3 of the polishing composition; and (2) that the ratio of polishing particles having sizes of 1 ?m or more is 0.001% by weight or less to the entire polishing particles in the polishing composition. The polishing composition is suitable for polishing substrates for precision parts including, for example, recording disk substrates, such as magnetic disks, optical disks, and opto-magnetic disks, photomask substrates, optical lenses, optical mirrors, optical prisms and semiconductor substrates, and the like.

Abstract: A polishing composition for a hard disk substrate includes alumina particles, silica particles, and water. The volume median diameter of secondary particles of the alumina particles measured by a laser beam diffraction method is 0.1 to 0.8 ?m. The volume median diameter of primary particles of the silica particles measured by transmission electron microscope observation is 40 to 150 nm. The standard deviation in number-basis particle size of the primary particles of the silica particles measured by the transmission electron microscope observation is 11 to 35 nm. The polishing composition for a hard disk substrate can preferably reduce the embedding of alumina abrasive grains into the substrate without impairing the productivity.

Abstract: The present invention provides a polishing composition containing an organic nitrogen-containing compound, an organic polybasic acid, an abrasive, and water, wherein the organic nitrogen-containing compound has in the molecule two or more amino groups, two or more imino groups, or one or more amino groups and one or more imino groups; a method for manufacturing a substrate with the polishing composition; and a method for reducing surface stains of a substrate with the polishing composition. The polishing composition can be suitably used, for example, in the manufacturing step for a substrate for a hard disk such as a memory hard disk.

Abstract: A polishing composition for memory hard disk containing water and silica particles, wherein the silica particles have a particle size distribution in which the relationship of a particle size (R) and a cumulative volume frequency (V) in a graph of particle size-cumulative volume frequency obtained by plotting a cumulative volume frequency (%) of the silica particles counted from a small particle size side against a particle size (nm) of the silica particles in the range of particle sizes of from 40 to 100 nm satisfy the following formula (1): V?0.5×R+40 (1), wherein the particle size is determined by observation with a transmission electron microscope (TEM). The polishing composition of the present invention can be even more suitably used for the manufacture of a substrate for precision parts such as substrates for memory hard disks.

Abstract: The present invention preferably provides a polishing composition for a hard disk substrate, containing aluminum oxide particles and water, wherein secondary particles of the aluminum oxide particles have a volume-median particle size of from 0.1 to 0.7 ?m, and particles having particle sizes of 1 ?m or more of the aluminum oxide particles are contained in an amount of 0.2% by weight or less of the polishing composition; and a method for manufacturing a hard disk substrate using the polishing composition. By using the polishing composition and the method for manufacturing a substrate of the present invention, for example, a hard disk substrate suitable for high recording density can be provided in high productivity.

Abstract: The present invention provides a polishing composition containing an organic nitrogen-containing compound, an organic polybasic acid, an abrasive, and water, wherein the organic nitrogen-containing compound has in the molecule two or more amino groups, two or more imino groups, or one or more amino groups and one or more imino groups; a method for manufacturing a substrate with the polishing composition; and a method for reducing surface stains of a substrate with the polishing composition. The polishing composition can be suitably used, for example, in the manufacturing step for a substrate for a hard disk such as a memory hard disk.

Abstract: A method for manufacturing a substrate, a polishing process for a substrate, a method of reducing microwaviness for a substrate, each including the step of polishing a substrate to be polished with a polishing composition containing an abrasive and water with a polishing pad of which surface member has an average pore size of from 1 to 35 ?m; and a method of reducing scratches for a substrate, comprising the step of polishing a substrate to be polished with a polishing composition comprising an abrasive, an oxidizing agent, an acid, a salt thereof, or a mixture thereof and water, with a polishing pad of which surface member has an average pore size of from 1 to 35 ?m. The method for manufacturing a substrate can be used for finish polishing of a memory hard disk or for polishing of a semiconductor element.

Abstract: A polishing composition containing an abrasive and water, wherein the polishing composition has a pH of from 0.1 to 7, and satisfies the following conditions: (1) that the number of polishing particles having sizes of 0.56 ?m or more and less than 1 ?m is 500,000 or less per 1 cm3 of the polishing composition; and (2) that the ratio of polishing particles having sizes of 1 ?m or more is 0.001% by weight or less to the entire polishing particles in the polishing composition. The polishing composition is suitable for polishing substrates for precision parts including, for example, recording disk substrates, such as magnetic disks, optical disks, and opto-magnetic disks, photomask substrates, optical lenses, optical mirrors, optical prisms and semiconductor substrates, and the like.

Abstract: A polishing composition for a substrate for memory hard disk, comprising silica particles in an aqueous medium, wherein the silica particles satisfy a specified relationship between an average particle size of the silica particles on the number basis and a standard deviation on the number basis, wherein the average particle size is obtained by a determination by transmission electron microscope (TEM) observation, and wherein a particle size and a cumulative volume frequency in a range of particle sizes of from 60 to 120 nm satisfies a specified relationship; a method of reducing microwaviness of a substrate for memory hard disk, comprising the step of polishing the substrate for memory hard disk with the polishing composition; and a method for manufacturing a substrate for memory hard disk, comprising the step of polishing a Ni—P plated substrate for memory hard disk with the polishing composition.

Abstract: A method for manufacturing a substrate, a polishing process for a substrate, a method of reducing microwaviness for a substrate, each including the step of polishing a substrate to be polished with a polishing composition containing an abrasive and water with a polishing pad of which surface member has an average pore size of from 1 to 35 &mgr;m; and a method of reducing scratches for a substrate, comprising the step of polishing a substrate to be polished with a polishing composition comprising an abrasive, an oxidizing agent, an acid, a salt thereof, or a mixture thereof and water, with a polishing pad of which surface member has an average pore size of from 1 to 35 &mgr;m. The method for manufacturing a substrate can be used for finish polishing of a memory hard disk or for polishing of a semiconductor element.

Abstract: A polishing composition for a substrate for memory hard disk, comprising silica particles in an aqueous medium, wherein the silica particles satisfy a specified relationship between an average particle size of the silica particles on the number basis and a standard deviation on the number basis, wherein the average particle size is obtained by a determination by transmission electron microscope (TEM) observation, and wherein a particle size and a cumulative volume frequency in a range of particle sizes of from 60 to 120 nm satisfies a specified relationship; a method of reducing microwaviness of a substrate for memory hard disk, comprising the step of polishing the substrate for memory hard disk with the polishing composition; and a method for manufacturing a substrate for memory hard disk, comprising the step of polishing an Ni—P plated substrate for memory hard disk with the polishing composition.

Abstract: A polishing composition for memory hard disk containing water and silica particles, wherein the silica particles have a particle size distribution in which the relationship of a particle size (R) and a cumulative volume frequency (V) in a graph of particle size-cumulative volume frequency obtained by plotting a cumulative volume frequency (%) of the silica particles counted from a small particle size side against a particle size (nm) of the silica particles in the range of particle sizes of from 40 to 100 nm satisfy the following formula (1):