Abstract: The present invention provides a powder classifier using a classification rotor capable of classifying powder with high efficiency and high accuracy. The classification rotor is attached to a rotating shaft as a body and rotatably supported in a casing. Within the classification rotor, a cavity is formed from the outer edge to the center and classifying vanes are provided around the circumference. The cavity is bent downwardly near the center with the lower end connected through a fine powder passage to a fine powder outlet. The outer edge of the classification rotor is connected to a coarse powder outlet. After feeding powder from a powder supply port, the powder is rotated by the classifying vanes such that coarse powder particles are taken out from the rough outlet by centrifugal force and fine powder particles are taken out by airflow from the fine powder outlet.

Abstract: Disclosed is a fiber of an organic, inorganic or metallic material or a simple substance wherein ultrafines of an inorganic or metallic material or a simple substance having an average particle diameter of 0.005-1 .mu.m are uniformly dispersed and deposited on 8-90% of the surface in a single layer. The fiber is produced by exposing a fiber of an organic, inorganic or metallic material or a simple substance to a gaseous stream forming ultrafines of an inorganic or metallic material or a simple substance by a vapor phase process, thereby contacting said ultrafines in the gaseous stream with said fiber in a state wherein the ultrafines are still active. The treated fiber is useful as a reinforcing material for a fiber reinforced composite.