Corrosion Assessment of Zn-Rich Epoxy Primers With Carbon Nanotube Additions in an Electrolyte With a Bacteria Consortium

Homero Castaneda,Monica Galicia

doi:10.3389/fmats.2019.00307

Abstract

Multifunctional coatings for corrosive environments have been developed to include two basic principle protection mechanisms: a barrier mechanism acting as a mass transfer process blocker, and cathodic protection mechanism acting as a charge transfer process promoter. Both mechanisms were assessed for Zinc-Rich Epoxy (ZRE) coatings in the presence of Carbon Nanotubes (CNTs) and exposure to a bioelectrolyte in order to study the evolution process during microbial corrosion conditions. The purpose of this study is to characterize in a comprehensive experimental platform the electrochemical response of a dual-protection zinc epoxy coating with different ratios of additive carbon nanotubes to active zinc particles upon exposure to a sulfate reducing consortium. Carbon nanotubes addition was found to affect both the prevailing mechanism at the coating interfaces and the formation of a biofilm at the coating surface that influenced the relatively dominance of the barrier protection mechanism. These multifunctional coatings with active particles could help to balance the charge transfer efficiency in terms of the sacrificial of zinc and barrier mechanisms, which influence biofilm formation and have potential consequences for biocorrosion on carbon steel.

Highlights

Most coatings used for microbiologically induced corrosion (MIC) in industry are designed to provide an effective barrier to inhibit corrosion processes and/or provide a biocidal effect
The open circuit potential (OCP) for the bare steel is more positive than the cathodic potential criteria because the galvanic effect results in a negative potential value, in which the steel faces immune thermodynamic conditions
The OCP for the bare steel 1008 was determined in a test where the sample was kept in the culture medium in bacterial consortium conditions, and the steel potential was found to be influenced by the biofilm and corrosion products formed at the surface of the substrate

Summary

Introduction

Most coatings used for microbiologically induced corrosion (MIC) in industry are designed to provide an effective barrier to inhibit corrosion processes and/or provide a biocidal effect. These coatings are synthetized using organic, inorganic, and hybrid approaches. Inorganic and hybrid protective coatings on steel have been proven to degrade when exposed to MIC in such anoxic conditions (Abdolahi et al, 2014; Enning and Garrelfs, 2014; Ciubotariu et al, 2015). Friendly coatings are being developed to improve their physicochemical properties to resist microbiological attack, either in aerobic or anaerobic conditions, while avoiding toxicity to the environment from the inherently toxic formulations of some coatings

Objectives

Methods

Results

Conclusion