New application of intercalation on improving toughness of carbon/carbon composites

Toughness is one of the key mechanical properties of carbon/carbon composites for practical application. The present paper reports a new method to improve the toughness of carbon/carbon composites by intercalation of bromine into the graphite microcrystals of pyrolytic carbon. The intercalated pyrolytic carbon was characterized by X-ray diffraction (XRD), TG and DSC. The XRD results confirm that the graphite microcrystals of pyrolytic carbon could be intercalated by bromine, although the weight loss in TG measurement indicates a low content of the intercalation in the pyrolytic carbon. According to the three-point bending test, the flexural strength of carbon/carbon composites with bromine intercalation decreases 10%, while the flexural modulus and deflection increases 10 and 18%, respectively. At same time, a tough-like fracture mode can be observed in the intercalated carbon/carbon composites. The involved mechanism of the improving toughness of carbon/carbon composites will be discussed. (c) 2005 Elsevier B.V. All rights reserved.