Thin graphite skin on glass-like carbon fiber prepared at high temperature from cellulose fiber

Abstract

as precursor fibers. The fibers were produced by Lenzing Co., Australia and supplied by Moririn Co. Ltd., and the trade name is Lyocell. The diameters of the fibers were around 3–4 lm. These fibers were heated to 900 C with a heating rate of 2 C/min in nitrogen atmosphere using an infrared image furnace and kept at this temperature for 2 h. The 900 C-treated fibers were further heated to 3200 C with a heating rate of 20 C/min in argon atmosphere using a graphite resistance furnace and kept at this temperature for 10 min. Scanning electron microscope (SEM) observations were carried out for the surfaces and cross sections of the 3200 C-treated carbon fibers. Transmission electron microscope (TEM) observations were made for the cross sections of the carbon fibers. A 0 0 2 X-ray diffraction (XRD) measurement was made for the pulverized sample of the carbon fibers using CuKa radiation and silicon powder as an internal standard. Maximum transverse magnetoresistance Dq/q was measured for a single filament of the carbon fiber at 77 K in fields up to 1 T. In order to examine the surface structure of the carbon fiber, the first order Raman spectra were measured for some of single filaments of the carbon fibers at room temperature in air using a 514.5 nm line of an argon ion laser. The SEM images of a surface of the 3200 C-treated carbon fiber and cross section perpendicular to the fiber axis are shown in Fig. 1. The diameters of the fibers were around 2–3 lm. Even after the heat treatment at 3200 C, a granular texture being characteristic of glass-like carbon [8] was observed on the cross section.