Microscopic behavior on the protection of polyacrylonitrile-based carbon fibers from thermal oxidation

Abstract

The surface of polyacrylonitrile-based carbon fiber was appropriately coated with dilute phosphoric acid to protect or retard its thermal oxidation occurring during an exposure to high temperatures above 600 C in air. Microscopic behavior on surface damage and size change in the uncoated and coated fibers was compared using thermogravimetric and scanning electron microscopic techniques. The result showed that the state of the carbon fiber surface was found to be remarkably improved by the coated phosphorous compound, minimizing the surface pitting, and size reduction of carbon fiber by high temperature oxidation. The microscopic evidence for the effective protection of carbon fiber from thermal oxidation also indicated that use of this technology may be positively considerable to other related materials.