MICROSCOPIC BEHAVIOR ON THE PROTECTION OF POLYACRYLONITRILE-BASED CARBON-FIBERS FROM THERMAL-OXIDATION

The surface of polyacrylonitrile-based carbon fiber was appropriately coated with dilute phosphoric acid to protect or retard its thermal ox idation occurring during an exposure to high temperatures above 600 de grees C in air. Microscopic behavior on surface damage and size change in the uncoated and coated fibers was compared using thermogravimetri c and scanning electron microscopic techniques. The result showed that the state of the carbon fiber surface was found to be remarkably impr oved by the coated phosphorous compound, minimizing the surface pittin g, and size reduction of carbon fiber by high temperature oxidation. T he microscopic evidence for the effective protection of carbon fiber f rom thermal oxidation also indicated that use of this technology may b e positively considerable to other related materials.