Investigation of the interfacial reaction between multi-walled carbon nanotubes and aluminum

Aluminum (Al)/carbon nanotube (CNT) composite films were fabricated by sputtering pure Al on the surface of aligned multi-walled CNT arrays. Heat treatment was performed in the temperature range 400-950 °C. The interfacial reaction between the Al and the CNTs was investigated by annealing the samples at various temperatures. The results indicated that aluminum carbide (Al₄C₃) was formed at the interface between the Al and CNT layers, and microscopy observation revealed that the reaction generally occurred at locations containing an amorphous carbon coating, at defect sites, and at open ends of CNTs. Because the nanosized CNTs are precursors for carbide formation, the Al₄C₃ formed is also nanoscale in size. The carbide formed on the surface as well as on the tips of the CNTs improves the interfacial interaction between the CNTs and the Al layers. This also contributes to the enhancement of the mechanical properties of the composite. Our investigation demonstrated that chemical vapor deposited CNTs are a suitable candidate as reinforcing material for Al and other metal matrices.