Structural effect of different carbon nanomaterials on the corrosion protection of Ni–W alloy coatings in saline media

Abstract

Ni–W alloy matrixes were reinforced with different carbon nanomaterials (CNMs) of fullerene, single- and multi-walled carbon nanotubes (SWCNTs and MWCNTs), and graphene oxide nanosheets (GONSs). Experiments were focused on elucidating the effect of CNM shape on the microstructures and the corrosion parameters of the obtained coatings. The corrosion behavior of the coatings was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy methods in saline media. The experimental data of the corrosion current density, the corrosion rate and the polarization resistance indicated that the presence of CNMs in coatings improves their quality. Also, the type of carbon nanomaterial incorporated into the nanocomposite coatings was proved to play a key role in the improvement of their corrosion parameters. The morphology of the surfaces and the possible corrosion products were investigated by SEM and EDX analysis. In this regard, the nanocomposite coatings containing asymmetrical CNMs, MWCNTs and GONSs were smoother, less cracked and more resistant to corrosion in comparison to the coatings of the Ni–W alloy or nanocomposites including symmetrical nanofillers (fullerene).