Vapor-grown and graphitized carbon fibers, process for preparing same,

Abstract

There are disclosed vapor-grown and graphitized carbon fibers capable of forming composite materials having the vapor-grown and graphitized carbon fibers contained at a high packing density and forming molded members consisting substantially solely of the vapor-grown and graphitized carbon fibers, a process for the preparation of the vapor-grown and graphitized carbon fibers, the molded member, and the composite member. The vapor-grown and graphitized carbon fibers have a mean fiber diameter of 5 .mu.m or smaller, a mean fiber length of 90 .mu.m or shorter, a mean aspect ratio of from 1 to 18, and a spin density of 8.times.10.sup.18 spins/g or less, when measured by the electron spin resonance absorption method. Such vapor-grown graphitized carbon fibers are prepared by graphitizing the vapor-grown carbon fibers at 2,000.degree. C. or higher and then fracturing them by applying a high impact thereto. The molded members can be formed, for example, by hydrostatic pressure-isotropic pressure molding techniques, The composite members can be prepared by compounding the vapor-grown and graphitized carbon fibers with the matrix.