STRUCTURE AND DEFORMATION-BEHAVIOR OF CAR BON NANOTUBES REINFORCED NANOCRYSTALLINE C60 COMPOSITE

Carbon nanotube reinforced nanocrystalline C60 was prepared at room te mperature by drawing the composite sheathed in silver tube. Fine struc tures of the composite were examined by high resolution electron micro scopy (HREM) and the mechanical properties by conventional tensile tes ts. HREM observation shows that carbon nanotubes in the composite are defect free and aligned well in the direction of the wire. The stress- strain curve of the composite wire de-sheathed by evaporation of silve r through heat treatment gives approximately 20 times increase in the fracture stress over that of polycrystalline C60 with higher fracture strain (over 10%). The fracture surface of the wire shows that nanotub es were pulled out but not fractured. TEM observation of interface str ucture of C60 vapor deposited nanotubes as well as pull-out tests were performed of C60 single crystals vapor-deposited on single high elast icity carbon fibers which have similar surface structure as nanotube t o examine the origin of the large elongation of the composite. It has been inferred that shear deformation takes place in the carbon fiber/C 60 single crystal interface with little deformation of matrix but with out fracture of the fiber and that the pull out was mainly caused by t he shear deformation, which was probably made possible by a weak inter action between graphitic basal plane and C60. The experiments lead us to a new concept of a ductile C/C composite.