Overcoming the strength-conductivity trade-off dilemma in carbon nanotube/aluminum-copper fibers by diffusion interface and chemical reaction interface

Abstract

The carbon nanotube fiber has not shown its advantage and been widely used in many applications due to low conductivity. Depositing a metallic layer on the carbon nanotube fiber surface became an effective method. However, the strength of the carbon nanotube fiber decreases with increasing conductivity and coating thickness. Here, we deposited nanocrystalline metal coating on carbon nanotube fibers by magnetron sputtering. The coating consists of an ultrathin Al transitional layer and a Cu layer. After annealing, the Al atoms and Cu atoms diffused into the carbon nanotube fiber to form diffuse interface and chemical reaction interface, leading to the sliding resistance increase and contact resistance decrease between carbon nanotubes. As a result, the new composite fiber with a 2 μm thick Cu layer can exhibit a superhigh effective strength of 996 MPa and electrical conductivity of 2.6 × 107 S/m. This structure achieves both conductivity and strength increasing simultaneously.