Fabrication and densification of high performance carbon nanotube/copper composite fibers

An effective method to fabricate CNT/Cu composite fibers through combined physical vapor deposition (PVD) and drawing treatment is presented in this work. Dense copper films with various thicknesses were coated on CNT fibers using the PVD method for different deposition periods. One of the resulting films with ∼5 μm average thickness was subjected to drawing treatment. The results show that the density of CNT/Cu composite fibers was improved by 56% after the drawing treatment. Meanwhile, the alignment of the CNT fibers beneath the copper film showed improvement, as measured by polarized Raman spectrometry. The optimization in densification and alignment result in an increase of the tensile strength for the CNT/Cu composite fibers, from 258 ± 9 MPa to 515 ± 11 MPa (by 100%). Moreover, the electrical conductivity and ampacity increased from (7.64 ± 1.18) × 10⁶ S/m and (5.76 ± 0.36) × 10³ A/cm² to (1.37 ± 0.10) × 10⁷ S/m (by 79%) and (1.09 ± 0.06) × 10⁴ A/cm² (by 89%), respectively. Overall, these findings reveal that copper films play an important role in enhancing the tensile strength and current density, as well as reducing the electric resistance.