Abstract: The present invention relates to a polishing composition comprising water, alumina, and a chelating agent. It may optionally be incorporated with an aluminum salt and/or boehmite. The present composition permits efficient polishing and gives a polished surface having superior surface properties. The composition is suitable for polishing a memory hard disk.

Abstract: The present invention relates to a polishing composition comprising water, .alpha.-alumina and boehmite. The addition of boehmite contributes to an improvement of the polishing performance to provide an excellent polished surface and a high polishing rate. The polishing performance can further be improved by incorporating at least one member selected from the group consisting of a water-soluble metal salt, an ammonium salt and a metal nitrite. The polishing composition of the present invention is suitable for polishing metals, plastics or glass. It is particularly useful for polishing a surface of a memory hard disk plated with nickel or a nickel alloy.

Abstract: A process for producing a carbon fiber from pitch material, which comprises melt spinning pitch material through spinning nozzles to form precursory pitch fibers and oiling the precursory pitch fibers, followed by infusible treatment and carbonization and optionally by graphitization, characterized in that an oiling agent composed essentially of a silicone oil is applied to the precursory pitch fibers prior to or during the oiling operation.