Characterization of Short Time Marine Corroded Surfaces

Abstract

This work investigates the corrosion of offshore structural steel surfaces over particularly short timescales. The focus is on the short-term effects between surface treatment and coating application (typically several hours). Offshore structures are exposed to an aggressive marine environment, where substrates will be contaminated by aerosols containing salts within hours, even under mild weather conditions. Localised corrosion studies of the anodic and cathodic regions of S355 steel surfaces undergoing salt drop corrosion are characterised. Significantly, the corrosion products are found to grow rapidly and are inhomogeneous, porous, and amorphous. They evolve to higher oxidation state oxides quickly with corrosion time. Therefore, microscopic corrosion products will form on newly exposed substrates in marine environments, even before the protective paint is applied.

Corrosion inhibition of steel in seawater through surface phosphate formed from oil

“…Although iron (III) also dominates on the untreated surface, significant iron (II) and iron (0) character is evident for both treated and untreated samples. [17] Further deconvolution of the iron 2p spectrum to determine the contribution of an iron phosphate peak (expected at 712.8 eV) was not attempted due to Fe (III) peak domination, making peak separation difficult.…”

“…Efforts have recently been made to monitor corrosion and adsorption at early stages of the process, so relevant surfaces can be targeted for corrective treatment and/or protected prior to repainting. [17][18][19] Similarly, the initiation of the corrosion process has been observed through in situ observations, including electron microscopy, [20,21] optical spectroscopy, [22] electrochemistry, [23] and synchrotron techniques and neutron reflectometry. [24][25][26] Understanding the mechanisms of corrosion initiation allows corrosion to be arrested as soon as possible.…”

Surface Chemistry of Almandine Garnet

“…In marine environments, abrasive-blasted surfaces may be exposed for extended periods prior to the application of protective coatings; in this time, aerosol droplets that impact the surface can initiate corrosion and deposit inorganic ions. 10 Therefore, any change to garnet surfaces when exposed to these ions may affect the adhesion of coatings subsequently applied.…”

“…This emphasizes that the surface chemistry of the mineral could affect the performance of abrasive-blasted materials, such as carbon steel, and any coatings subsequently applied. In marine environments, abrasive-blasted surfaces may be exposed for extended periods prior to the application of protective coatings; in this time, aerosol droplets that impact the surface can initiate corrosion and deposit inorganic ions . Therefore, any change to garnet surfaces when exposed to these ions may affect the adhesion of coatings subsequently applied.…”