Bulk nickel–carbon nanotube nanocomposites by laser deposition

Abstract

Nickel–carbon nanotube (CNT) nanocomposites have been processed in a bulk form using a laser deposition technique, commercially known as the laser engineered net shaping (LENS) process. Mechanical milling of the powder feedstock consisting of nickel powders and CNTs before laser deposition has resulted in not only a more homogeneous distribution of the nanotubes in the nickel matrix, but also two distinct scales of reinforcements within the composite. The larger reinforcement scale consists of submicrometre to micrometre sized bundles of CNTs while the smaller scale consists of individual (or cluster of a few) CNTs within the nickel matrix. High resolution transmission electron microscopy studies indicate that the nickel/CNT interface is well bonded without the presence of any significant interfacial reaction product. The degree of disorder and defects in the CNT bundles in the nickel matrix varied as a function of bundle size as revealed by Raman spectroscopy results.