Corrosion Resistance of Electrochemically Synthesized Modified Zaccagnaite LDH-Type Films on Steel Substrates.

Michael Kahl,Teresa D Golden

doi:10.3390/ma14237389

Abstract

Modified zaccagnaite layered double hydroxide (LDH) type films were synthesized on steel substrates by pulsed electrochemical deposition from aqueous solutions. The resulting films were characterized by X-ray diffraction, scanning electron microscopy/X-ray dispersive spectroscopy, and Fourier transform infrared spectroscopy. Structural characterization indicated a pure layered double hydroxide phase; however, elemental analysis revealed that the surface of the films contained Zn:Al ratios outside the typical ranges of layered double hydroxides. Layer thickness for the deposited films ranged from approximately 0.4 to 3.0 μm. The corrosion resistance of the film was determined using potentiodynamic polarization experiments in 3.5 wt.% NaCl solution. The corrosion current density for the coatings was reduced by 82% and the corrosion potential was shifted 126 mV more positive when 5 layers of modified LDH coatings were deposited onto the steel substrates. A mechanism was proposed for the corroding reactions at the coating.

Highlights

Stainless steel has good corrosion resistance in various corrosive environments, with resistance derived from its chromium component
The electrochemical synthesis of hydroxides can occur by electrogeneration of base via a nitrate reduction at the working electrode interface (Equation (1)) [41]
DevelopedThe to electrochemically deposit modified zaccagnaite a stainless-steel electrodeposition occurred in mulzaccagnaite films onto a stainless-steel substrate

Summary

Introduction

Stainless steel has good corrosion resistance in various corrosive environments, with resistance derived from its chromium component. A minimum of 12% chromium allows for the formation of a protective chromium oxide layer. The oxide layer is self-repairing in oxygen-rich environments [8]. Stainless steels are susceptible to localized corrosion in various environments [9,10]. Stainless steels are often coated to prolong lifetime when utilized in a chloride environment [11,12]. There have been several studies showing the potential of using layered double hydroxides (LDHs) which are anionic clays as coatings, for metal or alloy substrates [13,14,15,16]

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Conclusion