Fabrication and electrochemical characterization of Zn–halloysite nanotubes composite coatings

Abstract

Zinc–halloysite nanotube (HNT) composite coatings through electrodeposition technique were successfully fabricated on mild steel substrate. As a comparison, pure zinc coating was also prepared. The composites were deposited in the presence of the surfactants cetyltriammonium bromide (CTAB) and sodium lauryl sulfate (SLS). The effect of the addition of nanoparticles and surfactants on the deposition, crystal structure, texture, surface morphology and electrochemical corrosion behavior were investigated. For the characterization of the electrodeposits, techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis were used. Both the additives HNTs and surfactants polarize the reduction process and thus influence the deposition process, surface nature and electrochemical properties. Electrochemical experiments, such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies, carried out in 3.5% NaCl solution show higher corrosion resistance by HNT incorporated coating, which was fabricated in the presence of CTAB. Microhardness of the deposits was evaluated and the composite with higher incorporation of nanoparticles in the presence of CTAB exhibited the highest value.