Modification of the Surface of a Carbon Fiber under High-Fluence Irradiation with Carbon Ions.

The results of the effect of high-fluence irradiation (fluence ~3 × 10¹⁸ cm^–2) with 30-keV C⁺ ions at a temperature of 250°C on the structure and surface morphology of polyacrylonitrile-based carbon fibers reinforcing the composite KUP-VM are presented and discussed. Scanning electron microscopy shows that the irradiation of carbon fibers with their own ions does not lead, as in the cases of irradiation with ions of inert gases and nitrogen, to corrugation of the fiber surface. The roughness of the composite surface remains comparable to the nonirradiated sample. According to Raman-spectroscopy data, irradiation with carbon ions at temperatures above that of dynamic annealing of radiation-induced damage leads to the formation of a disordered graphite-like layer, as in the cases of irradiation with inert-gas ions. The lack of corrugation of the carbon-fiber surface under irradiation with carbon ions is associated with the lack of a gradient of radiation-induced damage in the modified layer and a texture characteristic of a carbon-fiber shell based on polyacrylonitrile. [ABSTRACT FROM AUTHOR]