Abstract

In this work, benzotriazole (BTA) inhibitors were deposited on the surface of nano-SiO2 particles, which served as the inhibitor carriers. Polyelectrolytes were then adsorbed on the particle surface by a layer-by-layer method to prepare the nanocontainers to store inhibitors. The inhibitor-loading nanocontainers were characterized by a number of techniques, including scanning electron microscopy, energy-dispersive X-ray spectrum, Fast Fourier Infrared spectrum and thermal gravimetric analysis. The corrosion resistance and the nano-container doped epoxy coatings was evaluated by electrochemical impedance spectroscopy. Results demonstrate that the SiO2 nanoparticles based polyelectrolyte nano-containers are successfully fabricated to store BTA. The nano-containers added in NaCl solution are able to inhibit the corrosion of the steel. The inhibiting performance is improved with immersion time. The inhibiting efficiency is over 66% after 24 h of testing. It is expected that the inhibiting performance further increases with the continuous release of BTA from the nano-containers with time. When the steel coated with the BTA loaded nano-containers is immersed in NaCl solution, the corrosion inhibition is time dependent upon the release of encapsulated inhibitors from the containers. The change of solution pH upon the coating damage and generation of corrosive environment may trigger the opening of the nano-containers for inhibitor releasing.

Introduction

Epoxy coatings are one of the most commonly used coatings for corrosion protection in oil/gas and pipeline industries. The coating separates metal structures from the corrosive environment, and serves as a physical barrier on the metal surface. However, the coating can experience degradation in service due to various reasons such as penetration of water and ions into the coating and disbondment of the coating from the substrate. 1,2 Particularly, when a corrosive environment is generated under disbonded coating or at coating defects on pipelines, and simultaneously, cathodic protection (CP) is shielded from reaching the pipe steel, corrosion would occur. Efforts have been made to improve the anticorrosion properties of coatings.3,4

Keywords:
flowline corrosion, Pipeline Corrosion, metals & mining, autonomic computing, Subsurface Corrosion, Corrosion Inhibition, water management, Production Chemistry, oilfield chemistry, well integrity
Subjects:
Production Chemistry, Metallurgy and Biology, Pipelines, Flowlines and Risers, Materials and corrosion, Well Integrity, Subsurface corrosion (tubing, casing, completion equipment, conductor), Corrosion inhibition and management (including H2S and CO2)
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2016. NACE International
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