Carbon nanotube growth on high modulus carbon fibres: Morphological and interfacial characterization

Carbon nanotubes (CNTs) were grown directly on the surface of carbon fibres, using the catalytic chemical vapour deposition. FeCo bimetallic catalysts were deposited on carbon fibres using a simple wet impregnation method. CNTs were synthesized over the prepared catalysts by the catalytic decomposition of acetylene at 750oC. The uniform CNT formation on the fibre surface was verified using scanning electron microscopy. Raman spectroscopy was employed to evaluate non-destructively the CNT growth and the CNT quality. Thermo gravimetric analysis and differential thermal analysis were employed as destructive methods to confirm the spectroscopic data. Single CNT-coated fibre fragmentation tests were performed to examine the interfacial shear strength (ISS) of the modified fibres. Acoustic emission was employed to monitor the fragmentation process in real time. Thus, the coated fibre structural integrity was assessed together with its stress transfer properties. Polarized optical microscopy was employed to cross validate the acoustic emission data. It was found that the ISS of the nanotube-reinforced interphase was improved without affecting the fibre mechanical properties.