Original Article

Fabrication and characterization of CNT-reinforced Ni-Co composite coatings: microstructural evolutions and corrosion behavior

¹ Materials Department, Engineering Faculty, Shahrekord University, 88186‑34141 Shahrekord, Iran
² Department of Materials and Metallurgical Engineering, Amirkabir University of Technology (Tehran Polytechnic), 15875-4413 Tehran, Iran

^* e-mail: sharifi@sku.ac.ir

Received: 25 October 2023
Accepted: 3 April 2024

Abstract

In this study, Ni-Co coatings were synthesized on 304L stainless steel substrates using the spin coating method and the effects of adding multi-walled carbon nanotubes (MWCNTs) on the microstructural, mechanical and corrosion properties of the produced coatings have been investigated. The morphology of the synthesized coatings containing high amounts of nickel was observed to be spherical. With increasing the cobalt content, a change from spherical to needle-fibrous morphology occurred in the microstructure of the coatings. Carbon nanotubes caused the accumulation of dislocations and increased the hardness of the coatings by restricting the movement of dislocations and the slipping of grain boundaries. Moreover, by adding multi-walled nanotubes to the coating structure, the preferred nucleation sites for nickel and cobalt were increased and the resulting coating became finer in the microstructure. Therefore, the maximum hardness and corrosion resistance were observed in the CNT-reinforced coating of the lowest cobalt content.